Search

Carbon materials with layered structure and high conductivity are promising electrode candidates for dual-ion batteries (DIBs). However, the size mismatch of electrolyte ions and interlayer spacing of carbon materials limits the overall performance of DIBs. Thus, finding an effective strategy to adjust the interlayer spacing of carbon materials is of great importance. Here, we describe an efficient electrochemical strategy combining ion pre-intercalation and gas evolution reaction treatment to expand the interlayer spacing and modify graphene layers of carbon fiber papers. Furthermore, through the theoretical calculation we have demonstrated that the anion adsorption energy is reduced and kinetics is accelerated by the introduction of functional groups on the graphene layer. After the electrochemical modification, the discharge capacity of CFP increases more than 50%, the transfer resistance reduces even more than 40% and the capacity retains 94% after 1000 cycles in an ionic liquid electrolyte. These promising results demonstrate an effective and convenient method to solve the size mismatch issue, and therefore, arouse the potentials of carbon materials and other materials with layered structure for high performance DIBs. [ABSTRACT FROM AUTHOR]

• Carbon paper electrode shows poor mechanical stability, affecting the AORFB performance. • The mechanical robustness of carbon cloth electrode contributes to a reliable and durable AORFB performance. • Carbon cloth electrode showed high stability when used on quinone oxidation–reduction cycles. • Electrochemical active sites on the carbon cloth increase current densities and AORFB power density. • Carbon cloth electrode provides higher AORFB power density at high electrolyte flow rate. Aqueous organic redox flow batteries (AORFBs) are emerging as promising candidates for efficient energy storage in grid-scale applications. In this study, we present a comprehensive analysis comparing the performance of thermally treated carbon paper and chemically oxidized carbon cloth electrodes, which have been extensively examined for their potential suitability in AORFBs. Results indicate that carbon cloth electrodes exhibit a higher concentration of oxygenated functional groups, contributing to enhanced electrochemical kinetics and improved electrochemical stability. These attributes translate to an AORFB with 62 times higher power density when compared to paper-based electrodes used. Through repeated charge-discharge cycles utilizing the BQDS║AQS model as a representative AORFB prototype, superior performance in the carbon cloth electrodes is consistently observed. Our findings even suggest the potential for optimizing the flow rate of the electrolyte to further enhance performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MIP paper-based electrochemical cell was developed for the determination of 5-hydroxymethylfurfural. • The linear concentration range was between 5.0 to 1000 µmol/L. • The device was successfully applied in different honey samples. The concentration of 5-hydroxymethylfurfural (HMF) has become one of the most useful parameters for the quality evaluation of honey − a crucial focus within the honey industry. In this work, a voltammetric molecularly imprinted polymer (MIP) paper-based electrochemical cell for the rapid quantification of HMF in honey is presented for the first time. Carbon ink was used to produce a custom-designed working electrode on chromatographic paper. The selected functional monomer was 4-aminobenzoic acid (ABA). MIP was obtained by electropolymerization directly on electrodes. The preparation process of the MIP, as well as the integrity of the paper platform, were investigated and optimized. Cyclic voltammetry was employed to characterize the sensor. Based on the optimized conditions, it revealed an imprinting factor of 13.5, a linear response in the range between 5.0 and 1000 µmol/L with a limit of detection of 0.608 mg kg−1. The sensor's practical applicability for the quantification of HMF in honey samples was successfully tested, demonstrating good performance compared with high performance liquid chromatography (HPLC). With the inherent sustainable properties of paper platforms, this cost-effective and disposable MIP paper-based electrochemical cell holds promise as a viable alternative for on-site monitoring of HMF in honey. [ABSTRACT FROM AUTHOR]

[Display omitted] • Disposable paper electrode produced from low-cost off-the-shelf materials. • Multivariate optimization of the paper electrode and the electroanalytical method. • Simple, low-cost, and sensitive electroanalytical determination of triclosan. This study introduces a disposable electrochemical sensor fabricated from readily available low-cost materials. The design features a three-electrode electrochemical cell made of a simple graphite dry lubricant and silicone sealant composite, screen-printed onto a sulphite paper substrate. The ideal composite mixture was stablished through factorial design. The sensors were applied to the electroanalytical detection of triclosan, an antimicrobial agent used in personal care products, with concerns about its impact on ecosystems and human health. A subsequent factorial design determined the optimal voltammetric conditions. This approach yielded a method with limits of detection and quantification of 0.05 μmol L–1 and 0.17 μmol L–1, respectively, with a linear range from 0.20 μmol L–1 to 10.30 μmol L–1 for triclosan. The method was successfully applied to analyze triclosan in tap water and personal care products, including toothpaste, mouthwash, and liquid soap, achieving recovery rates ranging from 96 % to 118 %. [ABSTRACT FROM AUTHOR]

The sensing mechanisms of common humidity sensors related to conductive active materials, which can be simply attributed to the variations in resistivity due to the separation of conductive materials and variations in polymer permittivity, are generally plagued by drawbacks such as cumbersome fabrication processes, high cost and low performance. Herein, we prepared Zn/Cellulose filter paper (CFP)/Nanoscale carbon ink (NCI)/Cu structure humidity power generators (ZHGs) based on the power generation principle of typical zinc-air batteries, using active metals with strong conductivity as electrodes, and the redox reactions that took place in the zinc-air battery can convert the chemical energy in the electrode into a stable electrical energy. The ZHG fabricated in this work can reach an extremely high open circuit voltage (V oc) of 0.803 V at 97 % RH and possesses an excellent power density of 312.24 μW/cm2, which has a good linear relationship (R 2 = 0.9669) over a wide humidity range (20–97 % RH). In addition, 10 ZHGs in series can charge commercial capacitors up to 3.83 V. Finally, the proof of concept demonstrated that the humidity power generation sensor can be well applied in human respiratory monitoring, finger non-contact switch, and power supply for light emitting diode (LED). [Display omitted] [ABSTRACT FROM AUTHOR]

Reforming of hydrocarbon which is an important hydrogen production method proceeds in two steps, i.e. steam reforming and shift reaction. Due to different thermodynamics, the two reactions are conventionally conducted at different temperatures. This study examines one step methane reforming by use of proton-conducting electrochemical cell in combination with a reforming catalyst. Promotion of the reforming reaction was intended by extracting hydrogen via electrochemical hydrogen pumping with a proton conductor cell. In order to compensate for the slow kinetics of the steam reforming, a paper catalyst loaded with Ni was placed in front of the electrochemical cell. Electrolyte support cells were used to verify this concept, and the effect of the electrochemical hydrogen pump was investigated from the composition of the outlet gas. Electrode support cells using a thin film electrolyte was used to reduce overvoltage. It is demonstrated that the steam reforming reaction and the shift reaction take place in one electrochemical cell. Effective catalyst placement and energy efficiency is discussed. Reforming of methane was performed for hydrogen producing with proton conducting SrZr 0.5 Ce 0.4 Y 0.1 O 3-δ (SZCY541) and Ni-loaded paper-structured catalyst (Ni-PSC). When Ni-PSC is used as anode, electrode-supported cell shows enough H 2 evolution rate in agreeing with Faraday's law. Image 1 • Methane reforming was examined using protonic SrZr0.5Ce0.4Y0.1O3-δ electrolyte. • Ni-loaded paper-structured catalyst effectively improved the conversion of CH 4 to H 2. • Electrode-support cell was more effective for steam reforming and the shift reaction. [ABSTRACT FROM AUTHOR]

As a basic component of batteries, separators are proposed to apart the two electrodes while allowing the transport of ionic charge carriers. Cellulose separators have attracted tremendous attention due to their excellent thermal stability and wettability. In this study, we prepare all-cellulose composite (ACC) separators coated with Zn 5 (OH) 8 Cl 2 ·H 2 O (ZHC) particles. The surface of the cellulose filter paper is partially dissolved by the 65% ZnCl 2 solution, forming a tortuous and porous all-cellulose composite membrane. At the same time, ZHC is generated in situ on the surface during the removal of residual ZnCl 2 from the cellulose, which effectively promotes the passage of a sodium ion (Na+) and substantially improves the cycling performance of the batteries. Density functional theory (DFT) calculations demonstrate that suitable adsorption energy on ZHC is favorable for promoting Na+ transport. The corresponding ACC separator exhibits high ionic conductivity (2.75 mS/cm) and Na+ transference number (0.82), correspondingly the assembled Na/hard carbon half-cells show an excellent reversible specific capacity (315 mA h/g at 25 mA/g) and cycling stability (the retention is 97.77% after 50 cycles at 50 mA/g), outperforming the glass fiber separator in both sodium-ion half-cell and full-cell. [Display omitted] • A novel cellulose-based separator is obtained by a facile sol-gel method. • In situ growth of ZHC on the separator is shown to facilitate Na + transport. • The separator exhibits a high Na + transference number (0.82). • The cells assembled with the composite separator show excellent performance. • The ZHC loading method can be extended to other separator systems. [ABSTRACT FROM AUTHOR]

This work describes the development of a paper-based platform for highly sensitive detection of diclofenac. The quantification of this anti-inflammatory drug is of importance in clinical (e.g. quality and therapeutic control) and environmental (e.g. emerging contaminant determination) areas. The easy-to-handle platform here described consists of a carbon-ink paper-based working electrode and two metallic wires, provided by a gold-plated standard connector, as reference and counter electrodes. The porous paper matrix enables the preconcentration of the sample, decoupling sample and detection solutions. Thus, relatively large sample volumes can be used, which significantly improves the sensitivity of the method. A wide dynamic range of four orders of magnitude, between 0.10 and 100 μM, was obtained for diclofenac determination. Due to the predominance of adsorption at the lowest concentrations, there were two linear concentration ranges: one comprised between 0.10 and 5.0 μM (with a slope of 0.85 μA μM−1) and the other between 5.0 and 100 μM (with a slope of 0.48 μA μM−1). A limit of detection of 70 nM was achieved with this simple device that provided accurate results with an RSD of ca. 5%. The platform was applied for diclofenac quantification in spiked tap water samples. The versatility of this design enabled the fabrication of a multiplexed platform containing eight electrochemical cells that work independently. The low cost, small size and simplicity of the device allow on-site analysis, which is very useful for environmental monitoring. Image 1 • Ultrasensitive paper-based electrochemical determination of an emerging contaminant. • Low-cost, disposable and multiplex electroanalytical device for the drug diclofenac. • A 60-fold sensitivity increase by preconcentration on a paper-based platform. • An 800-fold lower limit of detection preconcentrating DCF on paper working electrodes. • The paper-based platform provide wide concentration range (0.1-100 µM) and high precision. [ABSTRACT FROM AUTHOR]

Al-air batteries are generally fabricated by rigid and heavyweight materials such as metal or plastic, meanwhile a bulky electrolyte solution either in static or circulation is requisite to ensure their steady operation. Therefore, they are less suitable for powering flexible and portable devices with lower power demand, such as wearable electronics, point-of-care test assays, RFID tags, etc. This work develops a flexible and lightweight Al-air battery with much less electrolyte storage, which is totally fabricated on a cellulose paper. The Al foil anode is embedded inside the paper substrate during paper-making process, while the air-breathing cathode is deposited onto the paper surface using an oxygen reduction ink. Despite its simple structure and low cost, this flexible Al-air battery can deliver a satisfactory power density of 19 mW cm−2 with alkaline electrolyte, and its operation lifespan is as long as 58 h with only 25 mg Al when saline electrolyte is employed. The corresponding Al specific capacity is as high as 2338 mA h g−1. In addition, this battery exhibits an excellent flexibility when facing different bending angles from 60 to 180° and multiple bending times greater than 1000. Furthermore, a flexible current or voltage output can be easily obtained by scaling up or stacking the present flexible Al-air battery, respectively, and the corresponding stacking efficiency is as high as 94%. In the future, non-metal oxygen catalyst will be employed to improve its environmental friendliness, and hot-pressing will be adopted to further increase its robustness to external deformation. • A flexible Al-air battery is developed for powering flexible and portable devices. • Al anode is embedded inside the paper, while ink cathode is deposited on the paper. • Peak power density of 19 mW cm−2 and specific capacity of 2338 mA h g−1 is obtained. • Battery performance is very stable even it is bended to 180° and by 1000 times. • Battery scaling-up and stacking is very convenient and highly-efficient (94%). [ABSTRACT FROM AUTHOR]

Paper microfluidics is used to produce single layer galvanic and hybrid cells to produce energy that could power paper-based analytical sensors. When two aqueous streams are absorbed onto paper to establish co-laminar flow, the streams stay in contact with each other with limited mixing. The interface at which mixing occurs acts as a charge-transfer region, eliminating the need for a salt bridge. We designed a Cu Zn galvanic cell that powers an LED when two are placed in series. We also used more powerful redox couples (formate and silver, formate and permanganate) to produce higher power density (18 and 3.1 mW mg −1 Pd). These power densities are greater than previously reported paper microfluidic fuel cells using formate or methanol. The single layer design is much more simplified than previous reports of multi-layer galvanic cells on paper. [ABSTRACT FROM AUTHOR]

In this work, we present a multiplexed (eight simultaneous measurements) paper-based electrochemical device developed in a very simple way and using low-cost materials, such as paper, carbon ink and multifunctional connector headers. Meanwhile, we have also combined the paper-based electrochemical platform with a glass-fiber strip in order to integrate easily a sampling step. Both approaches, simultaneous measuring and sampling, have been applied to the determination of glucose using bienzymatic biosensors. They are fabricated by adsorbing the mixture of enzymes (glucose oxidase and horseradish peroxidase), as well as the ferrocyanide, mediator of the electron transfer, on the paper-based electrode. After drying, the measuring solution (containing either glucose standards or samples) is added and the eight corresponding chronoamperograms are recorded. In the case of the microfluidic approach for sampling purposes, the glass-fiber pad (sampler) is immersed in a container with the solution, which flows by capillarity until it reaches the working electrode. The integration of one more step of the analytical process advances towards real and useful lab-on-a-chip devices. With these designs, a linear range comprised between 0.5 and 15 mM was achieved for glucose determination, with an excellent precision. If the sampler is employed, it is not necessary to use micropipettes and, nevertheless, precise measurements are obtained. The RSD of the slopes obtained for different calibrations performed in different days, with different arrays of electrochemical cells and different solutions is ca. 1%. Accurate results are obtained in the determination of glucose in real samples (orange fruit and cola beverages). Image 1 • Precise sampling is integrated in a paper-based electroanalytical device for glucose biosensing. • Adding a sampler to a paper-based enzymatic sensor advances towards lab-on-paper platforms. • A paper-based simple electrochemical device for eight simultaneous measurements is presented. • A low-cost paper-based sensor samples which analyzes food samples with 8 simultaneous measurements is developed. • Accurate results are obtained for glucose determination in orange fruits and cola beverages. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A simple, low cost, and lightweight 3D origami-battery on paper was developed. • The battery was fabricated using printed wax and active electrocatalytic materials. • The 3D-structure contained two screen printed Zn/Fe 3 O 4 batteries in series that were activated with 6 M KOH electrolyte. Abstract A simple, low cost, and lightweight three-dimensional (3D) primary alkaline Zn/Fe 3 O 4 origami-battery fabricated from Whatman 1 paper was developed. The battery was created using printed wax to define the hydrophobic and hydrophilic barriers and active electrocatalytic materials for fabricating the electrodes. The boat-shaped 3D-battery consisted of two screen-printed Zn/Fe 3 O 4 batteries connected in series that were activated with a small volume of aqueous KOH solution. The metallic electrodes were first characterized outside the folded battery using electrochemical techniques. Subsequently, the electrodes and separator were assembled together in a triangle-shaped battery resembling the main structure of the boat-shaped 3D-device and this triangle-shaped battery was further optimized. The addition of water triggered the activation of the 3D battery delivering a maximum current and power of 7 mA and 3 mW, respectively. The 3D-Zn/Fe 3 O 4 -battery displayed an OCP of 2.2 V and a maximum current and power of 22 mA and 7.5 mW, respectively, in the presence of 6 M KOH electrolyte. These results demonstrate the potential of 3D origami-based structures and Zn/Fe 3 O 4 batteries as an alternative low cost energy source to power portable devices. [ABSTRACT FROM AUTHOR]

This work presents the development and optimization of a very low cost, miniaturized and lightweight aluminum/silver oxide (Al/AgO) primary battery. The system is implemented on painted paper supported electrodes and it is activated using a small amount of water. The anode contains an improved composite based on aluminum powder. The cathode is made using an electrical conductive silver epoxy ink. The device displays a paper-based core comprising the electrodes and the paper matrix separator, modified with a highly concentrated dry potassium hydroxide salt, inside a flexible laminated plastic structure that provides sturdiness to the system making it safe and portable for the user. The battery turns on by applying 80 μl of water and as a result the system produces a maximum capacity of 0.5 mAh when 1.6 mA cm −2 are applied. The generated electrical power of two batteries in series is then used to power a LED during approximately one hour. Although there is room for improvement, these results allow envisaging the battery as a real commercial portable power source and allow planning potential uses of this energy to power microelectronics demanding low power consumption, such as sensors or wearable electronics. [ABSTRACT FROM AUTHOR]

• Well-dispersed Sb-doped SnO 2 nanoparticle is used to modify carbon paper. • Two-step electrodeposition and in-situ oxidation are used to modify electrode. • Modified electrode is outstanding at active site, conductivity and hydrophilicity. • Modified electrode exhibits superior kinetics for both vanadium redox reactions. • Carbon paper as bifunctional electrode enhances VRFB performance greatly. Herein, we proposed a facile strategy for preparing well-distributed Sb-doped SnO 2 nanoparticles on carbon paper (CP) via electrodeposition and in-situ oxidation as bifunctional electrodes for vanadium redox flow batteries. SnO 2 and Sb-doped SnO 2 modified carbon paper (CP-SnO 2 and CP-SnO 2 /Sb) was respectively obtained by electrodepositing metals (Sn and Sn/Sb) nanoparticles, followed by a conversion to metal oxides with in-situ oxidation. CP-SnO 2 exhibited better electrochemical performance toward V3+/V2+ and VO2+/VO 2 + redox reactions than CP. This is because SnO 2 increases active sites and hydrophilicity, which accelerates electrochemical kinetic and mass transfer for vanadium redox reactions. CP-SnO 2 /Sb had better electrochemical activity than CP-SnO 2 , because smaller Sb-doped SnO 2 nanoparticles more effectively disperse through carbon fibers, producing more active sites. Furthermore, Sb doping improved conductivity of SnO 2. Briefly, CP-SnO 2 /Sb exhibited excellent hydrophilicity, abundant active sites, and good conductivity, resulting in superior electrochemical activity. We next employed CP-SnO 2 /Sb as bifunctional electrodes in cell. The cell using CP-SnO 2 /Sb had better cycling stability and more capacity retention during a 50-cycle charge–discharge test at 50 mA cm−2. CP-SnO 2 /Sb reduced the electrochemical polarization of cell at higher current density. Overall, the cell using CP-SnO 2 /Sb showed a 9% increase in energy efficiency compared to pristine cell (64.5%) at 150 mA cm−2. [ABSTRACT FROM AUTHOR]

• A paper-based Al-air battery successfully developed for miniwatt applications. • The battery can work with limited electrolyte supply without external pumping. • Low-cost and low-grade Al employed with satisfactory discharge efficiency. • The paper substrate suppresses the Al self-corrosion with alkaline electrolyte. • An efficient and modular stacking strategy for battery pack development. Conventional Al-air battery is not suitable for mini-watt applications due to bulky liquid storage and complex water management. To achieve successful simplification and miniaturization, an innovative paper-based Al-air battery is developed in this study, which employs cellulose paper as electrolyte substrate, low-grade Al foil as anode and carbon paper as cathode. Despite its simple structure and low cost, this battery achieves satisfactory power output together with high efficiency. With alkaline electrolyte, an open-circuit voltage of 1.6 V, a peak power density of 21 mW cm−2 and a specific capacity of 1273 mA h g−1 are obtained. With saline electrolyte, the battery can continuously work at 1 mA cm−2 for 5.6 h with only 3.5 mg Al. In addition, it is found that the paper-based electrolyte delivery can suppress Al corrosion in alkaline environment, enabling the direct utilization of low-grade Al resources. Moreover, the battery performance is improved by optimizing properties of its components, such as cathode catalyst, electrode area ratio and paper substrate thickness. Finally, a 5-cell battery pack is successfully developed, achieving an open-circuit voltage of 7.7 V and a stacking efficiency as high as 97%. By further scaling-up, this battery pack is successfully demonstrated for charging portable electronics. [ABSTRACT FROM AUTHOR]

Pyridinic and graphitic nitrogen are recognized as the most promising dopants for promoting oxygen reactions since they are beneficial to the formation of corresponding C–N bonds as efficient active sites. However, complete control of such efficient nitrogen-doping sites in carbon materials is difficult to realize in practice in a pyrolysis process. Here, we present maximized pyridinic and graphitic nitrogen-doped oxygen electrode via the precise use of nitrogen-containing precursors and carbonization temperature. The critical roles of pyridinic and graphitic nitrogen dopants in enhancing oxygen reaction activity are unraveled and this highly active material exhibits a remarkable half-wave potential of 0.89 V versus the reversible hydrogen electrode (vs. RHE) for oxygen reduction reaction (ORR) and a small potential gap of 0.78 V between ORR and oxygen evolution reaction (OER) in 0.1 M KOH, which is one of the best to date among metal-free bifunctional electrocatalysts. Both zinc-air batteries using liquid electrolytes and the all-solid-state batteries assembled with such air cathodes exhibit excellent cycle performance and reversibility, which can be expressly observed by in-situ X-ray diffraction (XRD) characterization. This nitrogen dopants engineering strategy gives an effective methodology to make full use of nanocarbon materials for their practical applications in next-generation powerful and durable energy devices. Image 1 • Maximized pyridinic and graphitic nitrogen-doping enables remarkable activity. • Large active surface area provides short diffusion paths for ions and charges. • Strong coupling between particles and electron collector ensures smooth mass transfer. • Zinc-air batteries exhibit excellent cycle performance and reversibility. [ABSTRACT FROM AUTHOR]

• Previously validated OFMSW hydrolysate was used to lab scale P(3HB) production. • The OFMSW hydrolysate is a suitable substrate for use as media in the batch phase. • Sugar rich plum concentrate promotes the production of P(3HB) in fed-batch phase. • Combining both substrates, the yield was 0.15 g P(3HB) per gram of sugar consumed. • The suggested process can integrate into a circular economy model. Municipal solid waste (MSW) is massively generated all over the world. Its organic fraction (OFMSW), which represents a high percentage of MSW, mainly contains biodegradable materials, namely food waste, paper and garden waste. The social cost of OFMSW treatment and/or disposal is a serious and widespread problem, particularly in highly populated areas. Thus, effective and innovative solutions, which include the upgrading of OFMSW, are being currently sought. In fact, the OFMSW abundance, availability and average composition suggest its considerable potential within the circular economy desideratum, paving the way to valorisation approaches. In this context, an OFMSW sugar-rich hydrolysate and its validation as a substrate for the production of the polyester poly(3-hydroxybutyrate) (P(3HB)), to date the only bioplastic easily biodegradable in marine environment, were successfully obtained in a previous study. Based on those results, this work addresses the upscaling of the fermentative production, in fed-batch mode, of P(3HB) by Burkholderia sacchari. The OFMSW hydrolysate was used as cultivation medium due to its balanced nutrient composition, while a plum waste juice, also rich in sugars, was applied as feed to the bioreactor. By implementing this strategy, a maximum P(3HB) production of 30 g·L−1 with an accumulation of 43% g (P(3HB))/g cell dry weight (CDW) after 51 h, was achieved. The use of the hydrolysate as initial medium resulted in higher CDW (71 g·L−1) than that of the simulated hydrolysate (62 g·L−1 in average), probably because the OFMSW hydrolysate favours biomass growth in detriment of P(3HB) production. [ABSTRACT FROM AUTHOR]

Mg/Al-hydrotalcite (HDT)-dispersed paper-structured catalyst (PSC) was prepared by a simple paper-making process. The PSC exhibited excellent catalytic activity for the steam reforming of model biodiesel fuel (BDF), pure oleic acid methyl ester (oleic-FAME, C 19 H 36 O 2 ) which is a mono-unsaturated component of practical BDFs. The PSC exhibited fuel conversion comparable to a pelletized catalyst material, here, conventional Ni–zirconia cermet anode for solid oxide fuel cell (SOFC) with less than one-hundredth Ni weight. Performance of electrolyte-supported cell connected with the PSC was evaluated in the feed of oleic-FAME, and stable operation was achieved. After 60 h test, coking was not observed in both SOFC anode and PSC. [ABSTRACT FROM AUTHOR]

Abstract: This study employed fuel cell gas diffusion layers (GDLs) consisting of carbon fiber paper made from carbon fiber felt with different yard weights in proton exchange membrane fuel cells (PEMFCs), and investigated the relationship between the yard weight of the carbon fiber paper and the fuel cell performance and thickness of the gasket. In this paper we discuss the relationship between carbon fiber felt with different yard weights and fuel cell performance and also explore the effect of carbon fiber paper thickness, air permeability, surface resistivity, and structural study. We focused on the material used for the gas diffusion layer in this study. Carbon fiber paper made in-house in this study contained 10wt% (all percentages are by weight unless otherwise noted) phenolic resin. When the tested area was 25cm2, the test temperature was 40°C, the gasket thickness was 0.06mm, and the yard weight 70gm−2, fuel cell current density was 1968mAcm−2 at a load 0.3V. When the gasket thickness was 0.36mm and yard weight was 190gm−2, fuel current density was 1710mAcm−2 at a load of 0.3V. [Copyright &y& Elsevier]

Abstract: This study uses fuel cell gas diffusion layers (GDLs) made from carbon fiber paper containing carbon black in proton exchange membrane fuel cells (PEMFCs) in order to determine the relationship between carbon black content and fuel cell performance. The connection between fuel cell performance and the carbon black content of the carbon fiber paper is discussed, and the effects of carbon black on the carbon fiber paper''s thickness, density, and surface resistivity are investigated. When a carbon fiber paper GDL contains 10wt% phenolic resin and 2% carbon black, and reaction area was 25cm2 and operating temperature 40°C, tests show that a carbon electrode fuel cell could achieve 1026.4mAcm−2 and maximum power of 612.8mWcm−2 under a 0.5V load. [Copyright &y& Elsevier]

Abstract: This paper seeks to develop a structure–performance relationship for gas diffusion layers (GDLs) of polymer electrolyte fuel cells (PEFCs), and hence to explain the performance differences between carbon paper (CP) and carbon cloth (CC). Three-dimensional simulations, based on a two-phase model with GDL structural information taken into account, are carried out to explore the fundamentals behind experimentally observed performance differences of the two carbon substrates, i.e. CC and CP, under low- and high-humidity operations. Validation against polarization data is made under both operating conditions, and the results indicate that the CC is the better choice as a GDL material at high-humidity operations due to its low tortuosity of the pore structure and its rough textural surface facilitating droplet detachment. However, under dry conditions, the CP shows better performance due to its more tortuous structure, which prevents the loss of product water to dry gas streams, thus increasing the membrane hydration level and reducing the ohmic loss. The present work is one step toward developing a science-based framework for selection of materials for next-generation, high-performance gas diffusion media. [Copyright &y& Elsevier]

Abstract: Proton conductive inorganic–organic membranes supported by glass paper were prepared from 3-glycidoxypropyltrimethoxysilane, tetraalkoxysilane and orthophosphoric acid. Hybrid membranes with a thickness of 70–80 μm were obtained by using two types of glass papers. The open circuit voltage of the test cell using the membrane supported by glass paper was 0.75 V. A power density of about 80 mW cm−2 was obtained with a current density of 300 mA cm−2 at a cell temperature of 130 °C under 7% relative humidity. [Copyright &y& Elsevier]

A general mathematical model is developed for electrochemical energy conversion in paper-based, capillary-driven, microfluidic flow cells. A two-dimensional version of the model is implemented to simulate a novel flow cell of this kind called PowerPAD. The methodology developed is validated against experimental data for this particular cell under both steady and unsteady modes of operation. It is shown that a 2D model can represent a 3D cell in unsteady flows provided that the Nernst-Planck equation is properly refined. The results are interpreted in terms of transient back-diffusion and crossover of the reactant species which are found to be the key factors controlling the electrochemical performance of this cell. The validated model is used to enhance the power output, runtime, and energy efficiency of this particular cell through altering its flow architecture and microstructure of electrodes and absorbent pad. The refined cell design is shown to roughly triple the power output and runtime of the device. The optimized design also outperforms the original design in terms of energy efficiency. The developed mathematical model, the fundamental understanding, and the proposed cell design may be utilized to develop new devices and concepts for capillary-based electrochemical systems, including biodegradable batteries, fuel cells, and electrolyzers. [Display omitted] • A dynamic mathematical model is developed for paper-based microfluidic flow cells. • A 2D model can represent a 3D cell subject to Nernst-Planck equation refinement. • The model reveals the unique working mechanism of imbibition and back-diffusion. • Crossover is identified as the key limiting factor for cell performance and runtime. • An optimized cell design is proposed with 3x performance improvement. [ABSTRACT FROM AUTHOR]

Highlights: [•] Simple, easy-to-use electrochemical paper-based analytical device. [•] The 3D device allows fast filtration and electrochemical detection. [•] The paper-based electrochemical cell was constructed using pencil and paper. [•] The paper based device allows p-nitrophenol detection at the micromolar level. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D paper-based microfluidic electrochemical device (3D-ePAD) was constructed. • Graphite-supported gold nanoparticles modified electrode was used as a working electrode. • Low-cost, disposable, simple, and miniaturized 3D-ePAD was performed for determination of GA in tea samples. The combination of µPAD with electrochemical transducers has gained advantages of miniaturization, high sensitivity, selectivity, simplicity of instrumentation, portability, rapid analysis, and so on. In this work, the development of a 3D paper-based microfluidic electrochemical device (3D-ePAD) for the determination of gallic acid (GA) was presented. The 3D-ePAD is composed of three electrodes (working, reference, and counter electrodes) in which the hydrophilic area of the working electrode was manually screen-printed and modified with graphite-supported AuNPs(AuNPs/C) ink. The evaluation of the electrochemical oxidation process of GA at modified and unmodified electrodes at 3D-ePAD indicated the improvement of anodic current responses at the AuNPs/C modified electrode which can be attributed to the intermolecular hydrogen-bonded network between AuNPs and GA. For quantitative determination of GA, the amperometric experiments were investigated under optimal conditions in which a linear relationship between the GA concentration and the recorded current was achieved. The sensor displays a good linear range of 1.0 to 100.0 μM and 0.1 to 2.0 mM for GA determination. The limit of detection (LOD) of 0.89 μM was achieved for GA by 3D-ePAD. Conclusively, the 3D-ePAD was performed successfully for the determination of GA in tea samples. [ABSTRACT FROM AUTHOR]

Abstract: An electrode platform printed on a recyclable low-cost paper substrate was characterized using cyclic voltammetry. The working and counter electrodes were directly printed gold-stripes, while the reference electrode was a printed silver stripe onto which an AgCl layer was deposited electrochemically. The novel paper-based chips showed comparable performance to conventional electrochemical cells. Different types of electrode modifications were carried out to demonstrate that the printed electrodes behave similarly with conventional electrodes. Firstly, a self-assembled monolayer (SAM) of alkanethiols was successfully formed on the Au electrode surface. As a consequence, the peak currents were suppressed and no longer showed clear increase as a function of the scan rate. Such modified electrodes have potential in various sensor applications when terminally substituted thiols are used. Secondly, a polyaniline film was electropolymerized on the working electrode by cyclic voltammetry and used for potentiometric pH sensing. The calibration curve showed close to Nerstian response. Thirdly, a poly(3,4-ethylenedioxythiophene) (PEDOT) layer was electropolymerized both by galvanostatic and cyclic potential sweep method on the working electrode using two different dopants; Cl− to study ion-to-electron transduction on paper-Au/PEDOT system and glucose oxidase in order to fabricate a glucose biosensor. The planar paper-based electrochemical cell is a user-friendly platform that functions with low sample volume and allows the sample to be applied and changed by e.g. pipetting. Low unit cost is achieved with mask- and mesh-free inkjet-printing technology. [Copyright &y& Elsevier]

A direct-readout photoelectrochemical (PEC) lab-on-paper device based on coupled an electricity generating system and paper supercapacitors was established for highly sensitive detection of adenosine triphosphate (ATP). Concretely, CdSe quantum dots (QDs) decorated ZnO networks assembled sensing surface provided outstanding photoelectric properties, on which glucose oxidase (GOx) labeled aptamer was subsequently immobilized via the hybridization chain reaction. With analytes present, specific recognition was stimulated by aptamer, resulting in labeled GOx released. Such released GOx could flow to electrochemical cell to conduct electrochemical redox reactions, which could effectively produce electricity that was stored by capacitor I. Sequentially, photoactive material produced an outstanding voltage due to the decrease of steric hindrance on the sensing interface, which was utilized for charging an external capacitor II. The two instantaneous current was acquired along with the discharge of capacitor I and II by digital multimeter (DMM) readout, respectively. The summational current values performed an increment in pace with the addition of target ATP concentration with the dynamic working range from 10 nM to 3 μM and a detection limit of 6.3 nM attained. Significantly, the signal amplified strategy utilizing as-generated electricity from electrochemical redox reactions were isolated from the photoelectrodes, which was beneficial for amplifying the signal response in the PEC matrices and the development of more efficient signal performance. Image 1 • A Photoelectrochemical lab-on-paper device based on coupled electricity generating system and paper supercapacitors. • High sensitivity and selectivity for ATP detection. • Use of electricity generated from redox electrochemical reactions for signal amplification. • A portable digital multimeter for signal readout. [ABSTRACT FROM AUTHOR]

Abstract: The porous carbon electrode in a fuel cell not only acts as an electrolyte and a catalyst support, but also allows the diffusion of hydrogen fuel through its fine porosity and serves as a current-carrying conductor. A suitable carbon paper electrode is developed and possesses the characteristics of high porosity, permeability and strength along with low electrical resistivity so that it can be effectively used in proton-exchange membrane and phosphoric acid fuel cells. The electrode is prepared through a combination of two important techniques, viz., paper-making technology by first forming a porous chopped carbon fibre preform, and composite technology using a thermosetting resin matrix. The study reveals an interdependence of one parameter on another and how judicious choice of the processing conditions are necessary to achieve the desired characteristics. The current–voltage performance of the electrode in a unit fuel cell matches that of a commercially-available material. [Copyright &y& Elsevier]

Abstract: Porous conducting carbon paper acts as an electrode backing material in a fuel cell. It not only assists in the flow of electrons and gases but also provides mechanical support to the MEA. The electrically conducting carbon paper (porosity ∼70%) was prepared using laminated assembly of chopped carbon fiber porous preforms and applying combined paper making and composite making technique. The green paper was subjected to different heat treatment temperatures (HTT), which was found to influence the characteristics of the paper significantly. The processing of the paper was carried out at a very fast carbonization rates, 900°C/h as compared to 10–20°C/h used conventionally, making the complete process highly cost efficient. The paper when used in the unit fuel cell assembly showed I–V performance comparable to that of the commercially available Toray carbon paper. [Copyright &y& Elsevier]

Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

We investigated the electrochemical performance of reduced graphene oxide (rGO)/carbon nanotube (CNT) hybrid papers as binder-free anodes for potassium-ion batteries. RGO/CNT hybrid papers were fabricated by vacuum filtration and thermal reduction. The potassium-ion storage ability of rGO paper was significantly enhanced by CNT incorporation and the electrochemical performance of the hybrid papers was related to the weight ratio of CNTs. The optimal rGO/CNT-30% paper can deliver an initial reversible discharge capacity of 351 and 223 mA h g−1 at a current density of 10 and 50 mA g−1, respectively. A capacity of 148 mA h g−1 was achieved after 200 cycles at a current density of 50 mA g−1. The enhanced performance of rGO/CNT hybrid papers is attributed to the formation of a 3D conductive carbon network, in which the graphene layers are bridged by CNTs. Such a structure could effectively facilitate the transport of electrons and potassium ions and provide more storage sites for potassium ions. Image 1 • RGO/CNT hybrid papers were fabricated by vacuum filtration and thermal reduction. • The potassium-ion storage ability of rGO paper was significantly enhanced by CNT incorporation. • RGO/CNT-30% paper delivered a reversible capacity of 232 mA h g−1 at a current density of 50 mA g−1, respectively. • The enhanced performance of rGO/CNT hybrid papers was attributed to the formation of a 3D conductive carbon network. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel flow-cell design was constructed. • Disposable and low-cost paper-based electrodes were simply fabricated and characterized. • AuNPs and MWCNTs showed a significant increase in current response against catecholamines. • HPLC-EC technique provided high selectivity and sensitivity for the determination of some catecholamines. • The applicability of the developed system was demonstrated by the analysis of biological samples. High performance liquid chromatography-electrochemical detector (HPLC-EC) is employed as a reliable device for the detection of catecholamines in blood or urine samples without any time-consuming extraction procedure. However, there is a need for the construction of cheap and easy-to-operate electrode assemble systems embedded in HPLC-EC. In this study, we present a disposable and low-cost paper-based electrode (PBE) assemble utilizing a nitrocellulose membrane, which serves support material in flow-cell device for HPLC-EC. A custom-built flow cell was inventively designed as specific to the prepared PBEs via stereolithography 3D printing. To gain the electrochemical signal enhancement, the working electrode was modified with gold nanoparticles and carboxylated-multi-walled carbon nanotubes (MWCNTs). Here, we focused on the construction of the paper-based electrode assemble and characterization of the flow cell device performance. To demonstrate the functionality of the flow cell device, we analyzed common catecholamines from spiked biological fluids using the optimized experimental parameters. Amperometric detection of the catecholamines was carried out at the potential of + 0.5 V and linear range was found to be 0.5–20.0 μg/mL, with a limit of detection in the range of 4.0–15.0 ng/mL. The obtained results confirmed our disposable paper-based electrode assemble to be promising for the construction of an electrochemical platform for reliable and fast detection of electroactive species. [ABSTRACT FROM AUTHOR]

We demonstrate a new polyvinyl alcohol (PVA)/Lyocell dual-layer (PLD) paper-based separator with high-efficiency and low-cost preparation process as a promising alternative to a commercialized composite separator applied in primary Zinc (Zn)-air batteries. The PLD paper-based separator is fabricated by dual-layer forming papermaking process, composed of PVA fiber layer and Lyocell fibrillated fiber layer. The dual-layer porous structure enables the PLD paper to have submicron-sized pores and good electrolyte retention. More notably, the pore size of the PLD paper can be tuned by controlling the specific surface area of Lyocell fibrillated fiber (herein, 7.1 m2 g−1 and 13.9 m2 g−1 Lyocell fibrillated fibers are exploited). Compared to a PVA/Lyocell monolayer (PLM) paper and a PLD paper containing 7.1 m2 g−1 fibrillated fiber, both a commercialized composite separator and a PLD paper containing 13.9 m2 g−1 fibrillated fiber provide superior discharge and high temperature storage performance. • The dual-layer paper-based separator with high-efficiency and low cost is developed. • Narrow pore size distribution obtained from the fibrillated fiber of larger specific surface area. • Change of pore structure caused by the dissolution and migration of the fibrillated fibers. • The PLD2 paper has similar discharge and high temperature storage performance as the commercialized CP separator. [ABSTRACT FROM AUTHOR]

Most recently, aqueous zinc-ion batteries (AZIBs) are the research focus because of their low cost, high safety, and eco-friendliness. In this respect, flexible binder-free electrodes have been investigated by several studies to keep pace with the development of wearable electronics. However, the mass loading of active materials in these electrodes is usually below 2 mg cm−2, considerably limiting the areal capacity. Herein, we report a paper electrode prepared via a facile vacuum filtration technique with a high mass loading of 5 mg cm−2 for the active material, namely, reduced graphene oxide (rGO)/δ-Na x V 2 O 5 ·nH 2 O nanocomposite. Thanks to the homogeneous distribution and synergistic effect of the active material, carbon nanotubes, and cellulose fibers, the electrode not only exhibits good mechanical property and high electrical conductivity but also displays impressive performances for AZIBs. It achieves an admirable areal specific capacity of 1.87 mAh cm−2 (corresponding to 374.9 mAh g−1 for the active material), substantially higher than that of other flexible binder-free electrodes for (hybrid) AZIBs. Meanwhile, this electrode also shows good rate capability and excellent long-term cyclability (with a capacity retention of 92% over 4000 cycles). This work opens new opportunities towards flexible free-standing electrodes. Image 1 • Flexible free-standing paper electrodes are prepared by vacuum filtration. • The paper electrode exhibits great performances for aqueous zinc ion batteries. • High mass loading of rGO/δ-NVO contributes to admirable areal specific capacity. • Large ion diffusion coefficient and favorable electrochemical kinetics are achieved. • Zn2+, H+, and H 2 O are reversibly co-intercalated into δ-NVO upon discharging. [ABSTRACT FROM AUTHOR]

• Cu(II) and Bi(III)-based MOFs are synthesized and used for CO 2 electroconversion. • The MOF-based GDEs give mainly alcohols (methanol and ethanol) and formic acid. • Reaction selectivity can be controlled by Cu/Bi loading and current density applied. • The synergy of Cu/Bi in CO 2 conversion is related with enhanced binding energies. • The materials remain pseudo-stable after five hours of operation. This work assesses the performance of Cu(II) and Bi(III)-based metal-organic framework (HKUST-1 and CAU-17, respectively) blends into the electroreduction of CO 2 to alcohols in a filter-press electrochemical cell. The bimetallic materials are supported onto porous carbon paper to form gas diffusion electrodes with a favorable continuous electrochemical conversion of CO 2 to methanol and ethanol, together with formic acid and gas-phase products (i.e. hydrogen, carbon monoxide and ethylene) in a 0.5 M KHCO 3 aqueous solution. The maximum reaction rates and faradaic efficiencies for CO 2 conversion to methanol and ethanol are r CH3OH =29.7 μmol·m−2·s-1 (FE = 8.6%) and r C2H5OH =48.8 μmol·m−2·s-1 (FE = 28.3%), respectively, at j = 20 mA·cm−2 which enhanced the values obtained at homometallic Cu and Bi-based materials independently. This denotes a synergic effect of Cu and Bi-based MOFs, associated with a favored interplay between the actives sites and reaction intermediates, prompting methanol formation and C C coupling reaction to ethanol. The results also show that reaction selectivity to produce alcohols can be controlled by Cu/Bi loading in the electrode surface and current density applied to the system. A 12% bismuth content seems to be the optimum for the production of alcohols (FE alcohols = 36.9%, S alcohols = 0.32). Regarding the current density, CO 2 reduction is more selective to methanol with a j =10 mA·cm−2 (FE CH3OH = 18.2%), while at j = 20 mA·cm−2, ethanol becomes the dominant CO 2 reduction alcohol (FE C2H5OH = 28.3%). The performance of the Cu/Bi-MOFs remains also pseudo-stable after 5 h of operation denoting the potential of the mixed metal-organic systems for the utilization of CO 2. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have attracted intense scientific attention as the most promising next generation energy storage device. However, the large-scale practical application of SIBs has been limited by exploring a low-cost and high performance anode material. Herein, hard carbon microfibers are successfully synthesized from renewable paper via simply carbonization procedure and proposed as anode materials for SIBs. The optimized carbonization at 1400 °C endows hard carbon microfibers high reversible charge capacity of 319.6 mAh g−1, good rate capability as well as excellent cycle life with capacity retention of 99.3% after 100 cycles. The sodium storage mechanism is further investigated by virtue of various technologies, indicating that sodium ions are stored in inter- and intra-layers. Remarkably, a full cell with the as-prepared anode and a Na 3 V 2 (PO 4) 3 cathode shows a favorable capacity of 243.8 mAh g−1 and stable cyclability of 218.9 mAh g−1 after 100 cycles. This study provides an opportunity for a cost-effective and renewable anode material for SIBs. [ABSTRACT FROM AUTHOR]

A printable Al-air battery is successfully developed for the first time by printing the Al ink and the oxygen reduction ink onto a cellulose paper. Currently, the printable Al-air battery can provide an open-circuit voltage of 1 V, a peak power density of 6.6 mW cm−2 and a maximum current density of 40 mA cm−2 when using salt water as the electrolyte. With 6 mg Al, the battery can discharge at 1 mA cm−2 for almost 6 h, leading to a high specific capacity of 951 mA h g−1. It is found that a moderate concentration of the polymer binder and a high concentration of the carbon support are of great importance to the ink functionality, while the hot-press treatment can dramatically improve the electrode performance and robustness. Finally, screen-printed battery prototypes with a specific electrode pattern are demonstrated for powering a small electric fan and a light-emitting diode. The present printable Al-air battery is a novel type of primary power source with low fabrication cost, high energy density and great environmental friendliness, which is especially suitable for powering various disposable printed electronics in the future. Image 1 • An all screen-printed Al-air battery is proposed for powering printed electronics. • The Al ink is composed of Al microsphere, carbon nanotube and cellulose binder. • Peak power density of 6.6 mW cm−2 and current density of 40 mA cm−2 can be obtained. • The battery discharge specific capacity is as high as 951 mA h g−1. • Hot-pressing is found to significantly improve the printed anode integrity. [ABSTRACT FROM AUTHOR]

In this work, a lightweight, ultrathin and flexible paper-based gel electrolyte is developed for liquid-free Al-air batteries, which employs a natural cellulose paper to store an alkaline gel. The as-fabricated electrolyte can be applied in either mechanical-rechargeable or single-use Al-air batteries, providing an open-circuit voltage (OCV) of 1.5 V and a peak power density around 3.5 mW cm−2. In addition, the battery discharge specific capacity is as high as 900 mA h g−1 even with low-purity Al. Moreover, a flexible Al-air battery can be obtained, which exhibits a stable performance under different bending angles. By optimizing the electrolyte properties including polymer concentration, gel loading and solution casting time, the battery power output can be further improved to 6.4 mW cm−2. Finally, two stacking strategies are investigated for developing Al-air battery packs, including both vertical stacking and planar stacking. Benefited from the complete ionic isolation among the single cells, both stacking strategies are demonstrated viable, with a normal OCV of 5.6 V for a 4-cell stack and a stacking efficiency as high as 87.5%. Such kind of liquid-free Al-air batteries are especially suitable for powering portable electronic devices with small rated power. • A paper-based gel electrolyte is developed for liquid-free Al-air battery. • The battery can provide an OCV of 1.5 V and a peak power density of 6.4 mW cm−2 • A high specific capacity of 900 mA h g−1 can be achieved even with low-purity Al. • A flexible Al-air battery is also successfully developed. • A convenient and efficient stacking of Al-air battery pack is demonstrated. [ABSTRACT FROM AUTHOR]

Lignin is a biopolymer generated from the pulp and paper industry as a natural resource. Lignin valorization is advantageous for biorefineries to produce aromatic compounds, fragrance, biofuel, material, and commodity chemicals, which could be an alternative of crude oil-derived products. However, several barriers are involved in natural lignin extraction and depolymerization, which need to be solved for its full utilization. The electrochemical oxidative upgrading of lignin into the oxygenated molecule is a promising method, which cleaves the C–O and C–C bond by direct oxidative or indirect oxidative method. As promising solvents, electrolytes, as well as catalysts in organic synthesis and electrochemical processes, ionic liquids (ILs) and deep eutectic solvents (DESs) have gained significant attention as dissolution media and catalysts for lignin depolymerization. In this work, aromatic carbon-rich lignin macromolecule depolymerization in ILs/DESs was reviewed to gain a better understanding of barriers, covering the interaction of ILs/DESs with lignin structure, degradation mechanism, thermochemical and electrochemical transformations, as well as COSMO-RS theoretical modeling and screening. In-situ generation of free radicals as catalysts (reactive oxygen species or H 2 O 2) for lignin degradation into value-added products was also discussed. All these studies give importance to ILs/DESs for thermochemical, electrochemical lignin cleavage and upgrading to value-added products for achieving sustainable future goals. [Display omitted] Synopsis: sketch representing the lignin valorization in the ionic liquids and their products. The pictorial demonstration shows the electrochemical oxidation of lignin model compounds in ILs/DESs and COSMO-RS study. ILs/DESs play an important role in dissociating the proton from molecules to generate anion, which donate the electron to anode and generate free radicals in electrolyte media. ILs/DESs electrolyte systems have seen high O 2 diffusion coefficients, which is realistic for ORR to generate ROS and H 2 O 2 as co-catalyst for oxidation (please not considered as H-type electrochemical cell). • Lignin oxidative degradation mechanism in ionic liquids (ILs)/deep eutectic solvents (DESs) are presented. • ILs and (DESs) are interacted via hydrogen bonding, π-π stacking with lignin for dissolution. • The electrochemical free radicals (ROS, H 2 O 2) generation for lignin degradation into value-added products was also discussed. • The theoretical modeling COSMO-RS was studied. [ABSTRACT FROM AUTHOR]

• The mechanism of organic electrode weakening self-discharge effect of dual-ion battery was explored. • The performance of metal-free dual-ion batteries in different ionic liquid electrolytes was investigated. • The method of reducing the dissolution of organic electrode in ionic liquid electrolyte was discussed. The strong self-discharge reaction is one of the key factors limiting the practical use of dual-ion batteries, which leads to low coulombic efficiency and discharge capacity loss. It is of great significance to effectively reduce the self-discharge effect through redox reactions between organic electrodes and electrolytes. Herein, a dual-ion battery study that uses 1,4,5,8-naphthalenetetracarboxylic dianhydride as the anode and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide as the electrolyte is conducted. Due to the introduction of organic materials, the storage mechanism of cations on the anode is changed, which weakens the self-discharge effect. The battery shows a low self-discharge rate of 6.12% h−1 and a high discharge capacity of 114 mAh g−1. The voltage declines by only 0.14 V after resting for 15 h due to the strong redox reaction between Pyr 14 + cations and the C O groups of NTCDA. Meanwhile, a double-layer filter paper system with small porosity is used to improve the cycle performance of the battery. [ABSTRACT FROM AUTHOR]

Recently, the scientific interest in developing rechargeable aluminium-ion (Al-ion) batteries has increased, triggered by its theoretical capacity, low cost and low reactivity of aluminium metal. One of the main challenges is the development of cathode materials that reversibly intercalate AlCl 4 − in its structure. The most promising candidates are carbonaceous materials of very different nature. However, no systematic analysis has been performed so far to investigate the intrinsic parameters that determine their electrochemical performance. Here, different commercial available carbons such as pyrolytic graphite (PG), expanded graphite (EG), synthetic graphitic flakes (SGF) and two different carbon papers (H23C3 and H23I1) are systematically evaluated as cathodes in Al-ion batteries. The influence of their graphitic degree, particle size, porosity and mass loading on the battery performance is elucidated. Electrochemical tests combined with ex situ XRD demonstrated that only highly graphitic materials can intercalate AlCl 4 − obtaining a good battery performance. Synthetic graphite flakes (SGF) showed the best specific capacity (85 mAh g−1), rate capability and cycle life (>1600 cycles) due to the fast diffusion of the AlCl 4 − through its structure. Finally, high mass loading cathodes (SGF-HML) showed extraordinary areal capacity (5.6 mAh cm−2), almost doubling the high energy cathodes for Li-ion batteries (3 mAh cm−2). Image 1 [ABSTRACT FROM AUTHOR]

With the rapidly evolving geo-political landscape and unceasing advancements in technology, sustainable energy security is a very important topic. Research indicates that electrochemical energy systems are quite promising to solve many of energy conversion, storage, and conservation challenges while offering high efficiencies and low pollution. The paper provides an overview of electrochemical energy devices and the various optimization techniques used to evaluate them. The optimization techniques include linear regression, factorial design, the Taguchi method, artificial neural networks, filters, and a combination of such methods to improve these systems. To support the growing interest in research, the bulk of this study focuses on a review of the most promising and highly researched electrochemical energy devices, such as fuel cells, batteries, and supercapacitors. The paper also provides modest commentary on hydrogen production technologies, electrochemical reactors, and membrane separation technologies, amongst other technologies. Building on a previous paper by the authors of this paper on artificial intelligence in hybrid renewable energy systems with fuel cells, this work provides a comparative review of optimization techniques for supercapacitors by highlighting key findings based on model accuracy. A summary of the advantages and disadvantages of the different major optimization techniques is presented. The paper concludes that a combination of optimization techniques is used to overcome the drawbacks of individual techniques, with adaptive filters being the most widely studied. This paper presents studies on the Design of Experiments (DoE) with the goal of building a better understanding of the relationships that exist between different operating variables in various electrochemical devices. • The electrochemical systems can be optimized for better performance with high accuracy. • The optimization techniques used are either model-based or data-driven. • Linear regression and artificial neural networks are the most common techniques studied. • Hybrid models could be applied to enhance systems' accuracy and minimize errors. [ABSTRACT FROM AUTHOR]

One of the major challenges towards the development of the conventional alkaline Zn-air battery is its spontaneous discharge caused by the unstability of the anode Zn in concentrated alkaline electrolyte. Utilization of a neutral electrolyte as the alternative to alkaline electrolyte is likely to be a promising strategy to overcome this issue because of much high stability of anode Zn in neutral solution. To realize the normal operation of the neutral Zn-air battery however, a crucial issue is how to ensure that the cathodic catalyst can efficiently electro-catalyze oxygen reduction reaction (ORR) in neutral solution. Herein, we report a facile preparation of Ni/Co-doped C-N nano-composite catalysts (NiCo/C-N) from direct pyrolysis of Ni/Co salt, polyaniline (PANI), carbon nanotube (CNT) and dicyandiamide. Among the as-synthesized catalysts, Ni 1 Co 3 /CN-3 presents high and stable ORR current density of 5.27 mA cm −2 in 0.5 mol L −1 KNO 3 solution at 2000 rpm. Electron transfer number of ORR on Ni 1 Co 3 /CN-3 catalyst is 3.78, showing a nearly completed reduction of O 2 to H 2 O. A neutral Zn-air battery with the prepared NiCo/C-N composite coated on carbon paper as the air electrode catalyst and metal Zn as the anode was constructed in 0.5 mol L −1 KNO 3 solution. For the catalyst Ni 1 Co 3 /CN-3, the open circuit voltage of the neutral Zn-air battery is 1.16 V, and the maximum power density is 38.5 mW cm −2 . The galvanostatic discharge time is 345.7, 160.6, 18.1 and 1.3 h as the discharge current density keeps 10, 50, 100 and 150 mA cm −2 respectively. A stable voltage plateau arises at various discharge current densities. The neutral Zn-air battery can repeatedly discharge after the zinc anode has been replaced, indicating that the synthesized ORR catalyst is an excellent cathode material for the neutral Zn-air battery. This kind of neutral Zn-air battery has a wide application prospect as mobile power supply. [ABSTRACT FROM AUTHOR]

Even for short space flights, such as manned flights to the Moon back in the 60s, it became extremely obvious that electric batteries are completely unsuitable because of their huge mass needed to store the required supply of onboard energy. Therefore, already in the 60s of the last century, the USA and the USSR took the path of using a hydrogen storage system using hydrogen fuel cells. Solar-hydrogen energy systems for spacecraft reliably provide energy for carrying out various kinds of unscheduled work on board and for eliminating emergency situations. Surplus energy is constantly accumulated on board in the form of the chemical energy of cryogenic hydrogen. The article presents too the result of the development of a solar-hydrogen power supply system for spacecraft, the onboard network of which provides slow and fast processes. This paper delves into designing digital control systems for power conditioning devices on the example of charging-discharging device based on a boost DC-DC converter. The device was implemented to condition a storage battery by properly charging and discharging it. A technique for constructing a small signal model of the converter has been developed. This involves constructing a block diagram using the discontinuous switching functions and analog models of electrical circuit components. The transfer functions of the analog controllers for the two-loop subordinate control system were derived. Then the procedure of a bilinear z-transform to the given transfer functions was applied. As a result, the discrete transfer functions of the digital controllers were obtained. Realization both analog and digital controllers in Matlab Simulink confirmed their identical behavior and stability within the power converter. Experimental studies of the static and dynamic waveforms of the digital control system showed controllability and stability of the charging-discharging device for the storage battery in typical operating modes. Thus, the method of synthesizing digital control systems for energy converters is proved valid and applicable for designing new power conditioning devices within modern power supplies. [ABSTRACT FROM AUTHOR]

To improve energy utilization efficiency for fuel cell vehicles (FCVs), it is crucial to pay particular attention to the coordination relationships between speed planning and energy management on the road with multiple signal lights. However, the coordination relationships are complex optimization problems with large computational loads, which make it challenging to consider speed planning and energy management simultaneously. Then, a co-optimization method based on Pontryagin's minimum principle (PMP) with the cooperative optimization algorithm is proposed for speed planning and energy management in the FCVs. An optimization control model for the speed planning problem online is established using the signal light timing model and solved using the PMP method to reduce the number of accelerations and decelerations, get closer to the desired speed, and decrease the demand power. Meanwhile, the optimization objective function for energy management is built to achieve the minimum hydrogen consumption, and the PMP method is re-applied to achieve a reasonable distribution of the output power of the fuel cell and lithium battery. Additionally, a cooperative optimization algorithm by conjunct use of the Whale optimization algorithm (WOA) and the Grey wolf optimization (GWO) is put forward to optimize the parameters in the PMP method. The simulation results indicate that the proposed method avoids waiting at red lights during the vehicle speed planning phase, minimizes speed fluctuations, and improves driving comfort. Moreover, compared to the Quadratic Programming (QP), when this method is utilized for power distribution between two sources, the FCHEV consumes 7.51% less hydrogen in route one and 1.35% less hydrogen in route 2. Besides, the method yields a more stable output power from the fuel cell. In summary, the method proposed in this paper fulfills the real-time optimization requirements for speed and energy. [Display omitted] • A co-optimization approach for speed planning and energy management is presented. • Speed planning and energy management are investigated using optimized PMP. • A cooperative WOA-GWO is proposed to optimize the parameters in the PMP. • Lower hydrogen consumption and faster calculation speed are achieved. [ABSTRACT FROM AUTHOR]

Lithium-oxygen (Li–O 2) batteries can exhibit high theoretical energy density and be surely suitable for potential energy storage. However, they suffer from early discharge termination and consequently low practical capacity, which has been regarded as the blockage of the diffusion of oxygen and the electron transfer on cathode surface. Herein, based on experimental results and theoretical simulation, it is confirmed that the discharge termination is largely caused by the surface adsorption of oxygen and the corresponding reaction intermediates. A TiO 2 -coated binder-free carbon paper has been prepared and used as cathode for Li–O 2 battery. During the first discharge, the discharge plateau at ca. 2.55 V has not been observed due to the weak adsorption of oxygen on TiO 2 surface, indicative of an early discharge termination of Li–O 2 battery. It is further identified that the formed vacancies on TiO 2 surface during lithiation/delithiation prevents the early discharge termination. Therefore, the interaction between oxygen and electrode surface plays a key role in discharge termination mechanism of Li–O 2 batteries. [ABSTRACT FROM AUTHOR]

Lignin, the second most abundant biopolymer and rich in aromatic entities, is a by-product of paper industry and mainly burned to produce energy. Its commercialization for high-value added products remains largely unexplored today. Herein, we explored the preparation of hard carbon anodes for sodium-ion batteries using the two most common lignin grades, i.e, lignin kraft and lignin sulphonate. The lignin kraft hard carbon (LK-HC) shows small specific surface area (1.8 m2 g−1) and a dense random-like morphology while the latter lignin sulphonate hard carbon (LS-HC) presents a high surface area (180 m2 g−1) and spherical particles containing macropores. Their electrochemical performances vs. Na+ revealed a steady capacity of 181 mAh g−1 over cycling for LK-HC, as compared to a capacity of 205 mAh g−1 for LS-HC which fades after 30 cycles due to an impurity-driven growth of a blocking solid electrolyte interphase (SEI). To circumvent this issue, an efficient washing procedure was successfully implemented enabling to obtain (LSW-HC) carbons which deliver a high and stable capacity (284 mAh g−1) along efficiency (78.1%). Image 1 [ABSTRACT FROM AUTHOR]

Today, hydrogen fuel cells (HFCs) have become very popular in various applications because of their ability to be a clean energy source. One of the difficulties associated with HFCs is their sluggish response to variations in the load. This paper presents a nested control strategy based on a type-2 neuro-fuzzy controller (T2NFC) to improve the HFC's dynamic response in a hybrid stand-alone power network using HFC and battery. A system model is constructed using Matlab-Simulink. An interleaved converter is used to draw the maximal power from the HFC and reduce the ripple in the HFC's current. Two T2NFCs control DC voltage and battery charge/discharge current. The robustness of the T2NFC is evaluated for input disturbance, output disturbance, and both disturbances. The results show that the proposed control strategy is robust against input and output disturbances. Also, it provides improved dynamic response of the HFC, lower ripple in HFC current, and less overshoot or undershoot in DC voltage both in transient and steady-state. For step reference input, the proposed controller improves settling time of 24.06 % and overshoot of 59.55 % compared to the conventional PI controller. The results verify the effectiveness of the proposed controller under different operating conditions of hybrid stand-alone power network with fuel cell and battery. • The response of HFC is enhanced, leading to faster and more accurate power generation. • The hydrogen fuel cell's current is experienced a significant reduction in ripples. • The hydrogen fuel cell is now being operated at its maximum power point. • A Type-2 Neuro-Fuzzy Controller is developed to provide robust control of the hydrogen fuel cell's output voltage. [ABSTRACT FROM AUTHOR]

This paper carries out a comprehensive analysis on an offshore wind farm equipped with a hybrid storage comprised of hydrogen and battery, from the perspective of economic effectiveness. To rapidly evaluate the system economy, a computationally efficient convex program that takes the nonlinear storage efficiencies into account is provided, which can simultaneously and synergistically optimize the storage sizing and energy management over a long offshore wind cycle. In the analysis, a case study on the optimal configuration and operation of the hybrid storage is thoroughly investigated, answering what the scalings are and how the storage functions in the offshore wind farm. Comparisons to other offshore wind farms with none or only one storage type further demonstrate the advantage of combining hydrogen plant and battery. Influences of the offshore wind electricity price of grid parity and hydrogen price on the system economies, in the terms of total annual cost, net annual profit and hydrogen production cost, are also discussed, revealing sensitivity and dependency of the scalings. Finally, this paper presents the future potential of applying hydrogen plant in the offshore wind farm, from the angles of hydrogen production cost and energy saving. • Nonlinear modeling of the offshore wind-hydrogen-battery system is presented. • Convex programming is applied to optimize the plant sizes and control of the OWHBS. • Comparative analysis on the economics of the OWHBS is provided. • Potential of the hybrid hydrogen-battery storage is assessed. [ABSTRACT FROM AUTHOR]