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Improving the reaction interface is imperative for increasing catalyst utilization and enhancing overall cell performance in proton exchange membrane electrolyzer cells (PEMECs). Herein, a thin Nafion-carbon-mixed microporous layer coated carbon paper (Nafion-C MPL/CP) is first developed as an efficient cathode liquid/gas diffusion layer for PEMECs. With the Nafion-C MPL/CP, low cell voltages of 1.64, 1.74 and 1.84 V are delivered, which are 50, 80 and 140 mV lower than those of the conventional bare carbon paper at 2, 4 and 6 A/cm2, respectively, achieving about 3-fold higher catalyst utilization. Meanwhile, superior performance is also demonstrated compared to the commercial PTFE-C MPL/CP. The remarkable performance of the Nafion-C MPL/CP should be attributed to the enhanced reaction interface, which not only provides rich active sites with abundant electron and proton transport pathways for the electrochemical reaction but also reduces the interfacial contact resistance and mass transport losses. Moreover, excellent stability of the Nafion-C MPL/CP is demonstrated at a current density of 1.8 A/cm2 with no performance degradation during over 100-h operation. Due to the enhanced reaction interface with significantly improved catalyst utilization, the developed Nafion-C MPL/CP shows great potential to reduce the hydrogen production cost and accelerate PEMEC commercialization. [ABSTRACT FROM AUTHOR]

• Variation of Young's modulus of Ga in the process of discharge (lithiation) was measured. • Self-healing ability of EGaIn to automatic repair the cracks resulted from charge/discharge. • The CNF/CNT@EGaIn NPs anode is free-standing, flexible and binder-free. Gallium-based liquid metals are considered as potential anode materials for lithium-ion batteries owing to their self-healing, non-poisonous advantages, as well as high theoretical capacity. However, due to the alloying/dealloying reaction mechanism to store lithium, Gallium-based alloys face huge volume change resulted in poor cycle life. Furthermore, the poor wettability of liquid metals on many kinds of substrates (carbon materials, stainless steel, etc.) and their strong ability to form alloys with many metallic current collectors (Cu, Al foil) make them hard to be designed into electrode with excellent electrochemical performance. One objective of this paper is to investigate Young's modulus of Ga discharged to different cut-off potentials, in order to gain a further understanding of mechanical property attenuation of Ga in the process of lithiation. Moreover, a three-dimensional (3D) free-standing electrode is fabricated by confining Ga-based liquid metal, EGaIn, in the matrix of carbon nanofibers/carbon nanotubes paper (CNF/CNT@EGaIn NPs). The network structure provides effective pathways for electrons and ions, as well as enough space to contain the volume expansion of EGaIn. The dense CNT layer plays a further role on preventing EGaIn from shedding of the conductive substrates. Obtained CNF/CNT@EGaIn NPs exhibits a good ionic/electronic conductivity and mechanical stability, delivers capacity of 351 mAh g−1 at 1.6 A g−1 and remains a reversible capacity of ∼420 mAh g−1 after 100 cycles at 800 mA g−1. This work could provide valuable insights into the development of Ga-based liquid metal anodes. [ABSTRACT FROM AUTHOR]

• 3D integrated Sn/CNT@N C gas diffusion electrode is proposed by phase inversion. • CNT@N C has integrated sponge-like microporous and finger-like macroporous layers. • The co-catalysis of N improves electron-proton-gas transfer for high performance. • Faraday efficiency of formate and CO is improved compared with Sn/carbon paper. A 3D integrated hierarchical porous N-doped Sn/CNT@N C gas diffusion electrode is proposed via phase inversion to synergistically improve electron-proton-gas transfer and efficiency of CO 2 reduction reaction (CO2RR). Hierarchical porous structure is tuned by the carbon nanotube additive during phase inversion, which integrates microporous layer and diffusion layer to decrease mass transfer resistance comparing with the 2D layer structure of commercial carbon paper. XPS results show that Sn/CNT@N C 800 contains pyridinic nitrogen and pyrrolic nitrogen with catalytic activity. EIS and LSV curves show that Sn/CNT@N C 800 is beneficial to reduce mass transfer resistance and increase current density after twice hydrophobic treatments. As a result, Sn/CNT@N C 800 shows higher CO 2 RR electrocatalytic activity. The reaction rate and Faraday efficiency of CO at 12 mA cm−2 increase by 40.2% and 40.6%, respectively compared with Sn/carbon paper. The reaction rate and Faraday efficiency of formate are also slightly higher than those of Sn/carbon paper. [Display omitted] [ABSTRACT FROM AUTHOR]

• A columnar liquid-crystalline triazine-based dendrimer has been incorporated as Li-ion battery anode. • The additional 1% carbon filler (CNT paper) in the triazine-based anode successfully boost the battery performance. • Systematical spectroscopic studies reveal that Li+ insertion in triazine and piperazine functional groups plays an important role in the Li+ storage mechanism. • The charge storage evaluation and kinetical studies unleashed the role of carbon filler on boosting capacitive contribution and accelerating Li+ transport. Owing to their highly tunable molecular structure and chemical stability, dendrimers consisting of triazine and piperazine moieties have been investigated. The present work describes the electrochemical performance of a columnar liquid-crystalline triazine-based dendrimer containing the linker with diaminopropane (DAP) as a lithium-ion battery anode. To elucidate the impact of conductive carbon filler in the electrode, a tiny amount of carbon nanotube (CNT) paper has been incorporated in the DAP anode. The battery performance revealed that the DAP anode has shown a high specific capacity of up to 444 mA h g−1 at 0.5 A g−1 after 200 cycles. Surprisingly, with an additional 1% CNT, the Li+ storage capacity of the dendrimer-based composite anode (DAP/CNT1%) significantly enhanced up to 656 mA h g−1. To the best of our knowledge, this is the first time that a triazine-based dendrimer has been utilized as an anode material in conjunction with a small amount of CNT to further boost its energy-storing capabilities through a synergy of capacitive storage mechanisms and improve Li+ transport. The efficient lithium storage of DAP/CNT composite further shows its amenability as organic electrode material for next-generation organic Li-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

• An all-solid-state thin-layer laminated cell realized calibration-free coulometric determination of K+ ions. • The cell achieved complete mass transport of the target ion from a 1 mm3 drop of the aqueous sample. • An originally prepared conducting-polymer-dispersed ink was cast on the carbon electrode. • The cell allows the calibration-free determination of K+ ions in a 1 mm3 drop of ten-fold-diluted serum. Calibration-free coulometric determination of K+ ions was realized using an all-solid-state thin-layer laminated cell with a simple laminate structure. The fabricated cell consists of a Ag/AgCl electrode, a plastic spacer for positioning the aqueous sample solution, an organic ion-selective membrane, and a conducting polymer/carbon electrode. An originally prepared conducting-polymer-dispersed ink was cast on a conductive carbon sheet (a screen-printed graphite electrode or carbon paper) to fabricate the conducting polymer/carbon electrode. The cell achieved complete mass transport of the target ion from a 1 mm3 drop of the aqueous sample to the organic ion-selective membrane under a constant potential between the Ag/AgCl electrode and the conducting polymer/carbon electrode, which generated electrical current for enabling the ion transfer. The electric charge obtained by integrating the electric current was used to estimate the molar amount of the target ion in the sample drop. For tetraethylammonium cations (TEA+; 20–200 μmol dm−3), the evaluated molar amounts corresponded to 92%–94% of the initial mole amounts. The repeatability estimated using the same cell was ±4%–6%, and the device-to-device reproducibility was ±4% for five cells. In terms of K+-ion detection (0.1–0.8 mmol dm−3) in sample drops containing NaCl (14 mmol dm−3), the evaluated molar amounts corresponded to 86%–92% of the initial molar amounts, indicating the promise of the all-solid-state thin-layer laminated cell for achieving the calibration-free determination of K+ ions in a 1 mm3 drop of ten-fold-diluted serum. [Display omitted] [ABSTRACT FROM AUTHOR]

• Cathodes consisting of carbon paper, electrode, and electrolyte are reconstructed. • An improved LBM model is developed for modeling the discharge process. • Time-dependent local porosity of cathode is considered by the proposed model. • The spatial distribution of electrode on O 2 diffusion and discharge are studied. The discharge process of lithium–oxygen battery (LOB) is a highly complicated multi-physics coupling phenomenon. Moreover, the cathode morphology presents a complex multi-scale structure with pore size ranging from nanometers to micronmeters, and plays a crucial role in determining the discharge performance. In this work, the cathodes consisting of carbon paper, electrode material, and electrolyte are first numerically reconstructed using a two-step reconstruction method considering the multi-scale morphology. A lattice Boltzmann model with an improved partial bounce-back scheme is proposed for modeling the discharge process given that the electrode porosity changes with the progress of discharge. The effects of micron-scale electrode spatial distribution on the O 2 diffusion and LOB discharge performance are investigated. Results show that the increment of the electrode dispersion degree increases the O 2 diffusion resistance due to the increase of electrolyte-electrode specific interface area. A large local electrode load near O 2 inlet leads to a high O 2 diffusion resistance and low O 2 concentration owing to the large specific interface area and electrode volume. Cathodes with the minimum electrode load and maximum electrode dispersion degree present the optimal specific capacity of LOB. However, the specific capacity first increases significantly and then slightly decreases with the increase of local electrode load. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS 2) can effectively improve the efficiency of hydrogen evolution reaction (HER) and reduce the cost of hydrogen production. However, MoS 2 is kinetically sluggish in alkaline media, which makes it difficult to apply directly to HER. In order to improve the applicability of MoS 2 in HER, this paper designs a hierarchical NiFe-LDH/MoS 2 nanosheet with a heterogeneous interface anchored on carbon fiber paper (CFP) to optimize the performance of MoS 2. The experimental results show that the NiFe-LDH/MoS 2 /CFP electrode in 1.0 M KOH exhibits excellent HER activity with only 88.5 mV overpotential at 10 mA cm−2. The good performance is attributed to numerous active sites on the NiFe-LDH/MoS 2 heterogeneous surface, the good electrical conductivity of MoS 2 and CFP, as well as the pores distributed on NiFe-LDH/MoS 2 that facilitate mass transfer. It is also found that the catalyst exhibits outstanding stability (24 h) in alkaline media. This work opens up new prospects for the development of high-performance electrocatalysts in alkaline media. [ABSTRACT FROM AUTHOR]

To further enhance the long-term durability of the cost-effective Ir-based catalysts, some acid-stable oxides are used as supports for acidic OER catalysts. Herein, taking carbon paper (CP) as the substrate, we prepared a self-standing IrW/WO 3-x @NC/CP electrode via a layer-by-layer modified method. Among it, N-doped porous C framework not only provides a large specific surface for the attachment of WO 3-x , but also makes up for the lack of conductivity of WO 3-x and accelerates the electron transport process. The interaction between Ir and W sites in the form of IrW alloy which has generated during the high-temperature calcination and the dispersed Ir in WO 3-x matrix improve the intrinsic catalytic activity. And due to the Pt-like effect of W and the tuning role of the electronic structure by the IrW alloy, IrW/WO 3-x @NC/CP with an Ir content of only 19.1 µg cm−2 exhibits excellent bifunctional activity in acidic media. To obtain 10 mA cm−2, IrW/WO 3-x @NC/CP just needs overpotential of 22 mV (for HER) and 206 mV (for OER) respectively with a mass specific activity of 4.008 A mg Ir −1 at 1.55 V. For the whole water splitting, it only requires 1.52 V and 1.70 V to reach 10 mA cm−2 and 100 mA cm−2 respectively, and can operate continuously for over 40 h. [ABSTRACT FROM AUTHOR]

In this work, the direct current vs. voltage (DC) characteristics, and the alternate current (AC) impedance of a 1D four-electrode electrochemical cell, operating under redox-cycling conditions, are presented and discussed. The analysis refers to a four-electrode electrochemical system with one positively biased working electrode, one negatively biased working electrode, one auxiliary electrode, and one reference electrode operating in a redox cycling mode. This configuration is useful, for example, for electrochemical biosensors that can benefit from the inherent redox-cycling amplification of the apparatus. An aqueous buffered electrolyte is assumed, containing electrochemically active species that can be oxidized on the anode, with a positive overpotential. Meanwhile, the product of the oxidation reaction can diffuse to the other working electrode which has a negative overpotential, where the product is reduced. The analysis in this paper assumes that oxidation is the dominant mechanism at the anode, reduction is the dominant mechanism at the cathode, and the transport between them is dominated by diffusion. Since it is a 1D model, an ideal lossless redox cycling, i.e. both working electrodes' currents (anodic and cathodic) are of the same magnitude with opposite signs, is assumed. Next, the small signal (AC) impedance of the electrochemical cell was calculated assuming that the AC signal modifies the oxidation reaction rate at the anode while the reduction reaction rate at the cathode is fixed. The impedance under redox cycling is calculated vs. frequency for various oxidation and reduction rates and both Bodé and Nyquist plots of the impedance are presented. The last part of the paper presents measured data for both DC and AC (i.e. Bodé and Nyquist plots) experiments with interdigitated array (IDA) electrodes, 5 & 10 μm spacing, operating under redox cycling conditions. The DC measurements were conducted in a 6 mM ferricyanide [K 3 Fe(CN) 6 ] in 0.1 M Phosphate Buffer Saline (PBS) solution, pH 7.4. The AC measurements were conducted in 10 mM & 100 nM ferricyanide (K 3 Fe(CN) 6) in 100 mM KNO 3 aqueous electrolyte. A critical discussion follows the results section where the highlights and problems of the models are discussed. [ABSTRACT FROM AUTHOR]

• An unsupervised feature extraction method of Li-ion batteries' EIS is proposed. • The latent variables are extracted automatically without prior knowledge. • The extracted latent variables are related to battery aging. • The capacity of batteries for uneven usage during degradation is estimated. • The proposed method generates reliable EIS data. In this paper, we propose an unsupervised feature extraction technique using a variational autoencoder and generative adversarial network (VAEGAN) that automatically extracts meaningful latent variables from the electrochemical impedance spectra (EIS) of lithium-ion (Li-ion) batteries. These variables accurately reflect the degree of Li-ion battery degradation and are closely related to its capacity. By analyzing the latent variables, it was found that the network can learn the effect of Li-ion battery capacity degradation on the EIS. The extracted latent variables are then used as input features for Gaussian Process Regression (GPR) to estimate the capacity of Li-ion batteries under uneven usage and with unknown historical data. The results show that the capacity prediction method proposed in this paper can significantly reduce prediction errors compared to the current state-of-the-art methods. The method not only provides a more reliable capacity estimation but is also robust to highly noisy EIS data, making it more suitable for practical application scenarios. [Display omitted] [ABSTRACT FROM AUTHOR]

• The proposed method can detect lithium plating earlier in the charging process. • Compared with other methods, this method is more sensitive and simple. • Combined with the model, the source of lithium plating signal is analyzed. • The universality of the method is verified by model simulation. Lithium plating is one of the most severe problems threatening the durability and safety of lithium-ion batteries. Therefore, accurate detection of lithium plating is crucial for the health management and charging control of lithium-ion batteries. In this paper, an impedance-based method is proposed to detect lithium plating of lithium-ion battery by comparing the normalized charing internal resistance profiles. After verifying that the model-based method is effective and feasible, it was used to analyze the reason and internal mechanism of the detection signal compared with the more frequently used lithium plating detection procedures today. The proposed detection method is more sensitive and accurate and expected to detect lithium plating in real-time during the charging process. Finally, the model showed that the method remained effective and reliable for lithium plating detection when the charging conditions changed. This paper, through the analysis, simulation, and experimental verification of online lithium plating detection method based on charging internal resistance, provides innovative ideas for the subsequent development of lithium plating detection and stimulates potential technologies for future development. [ABSTRACT FROM AUTHOR]

• Development of a dual-templated molecularly imprinted electrochemical sensor for the simultaneous analysis of brilliant blue FCF and tartrazine. • MIP film was generated by electro-polymerization of 3-aminophenyl boronic acid with brilliant blue and tartrazine as templates. • High surface area modification enables the formation of complementary binding sites for both analytes on the MIP sensor surface during fabrication. • Successful application of the developed sensor in real food samples. In this study, a dual-templated molecularly imprinted polymer-based electrochemical sensor was developed for the simultaneous analysis of two food additive dyes, brilliant blue FCF and tartrazine. Using a 3-aminophenyl boronic acid (3-APBA) monomer and the dual templates of brilliant blue FCF (BB) and tartrazine (TZ), the molecularly imprinted polymer (MIP) layer was electropolymerized on the carbon fibre paper (CFP) electrode. By using BB and TZ as template molecules along the electro-polymerization of 3-APBA, then removing both template molecules, the MIP film was generated on the surface of the CFP electrode. Due to the high surface area provided by modification, several complementary binding sites for template molecules are formed on the surface of the MIP sensor during this process of sensor fabrication. On the MIP/CFP electrode, the electrochemical behavior of BB and TZ was assessed. The monomer/template ratio, pH values, and influencing parameters like the electro-polymerization scanning cycles were all optimized. This sensor was applied to detect brilliant blue FCF and tartrazine in beverage and food samples using MIPAPBA/CFP electrode. [Display omitted] Graphical representation of the sensor fabrication process [ABSTRACT FROM AUTHOR]

Due to the shuttle effect brought by polysulfides, the commercialization of lithium-sulfur batteries still faces significant difficulties. Carbon interlayer is introduced to enhance the electrochemical performance of lithium-sulfur batteries, while the drawback that the interlayer will reversely affect the performance of the current collector was ignored. The current collector has a significant influence and contribution to the cycle stability of lithium-sulfur batteries. In this study, we looked into the electrochemical stability and corrosion situation of standard aluminum foil collectors in lithium-sulfur batteries with carbon interlayer. The results show that the introduction of carbon interlayer into the lithium-sulfur batteries will make aluminum foil and carbon paper form an electronic conduction path and galvanic corrosion occurs, accelerating the corrosion of aluminum foil. Therefore, we propose a new corrosion model. During the cycle, the surface of the aluminum collector becomes a non-dense passivation film and lithium polysulfide terminal (S T −1). Then, under the action of the carbon interlayer, the passivation film peels off and the oxide film is attacked by the electrolyte, thiosulfate and polythionate, resulting in pitting holes and ultimately accelerating the corrosion of the aluminum foil collector. This research has some guiding significance for the commercial application of lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Lithium-ion battery (LIB) occupies a major position in rechargeable batteries. However, if the state of charge (SOC) estimation of LIB is not accurate, it will lead to the decline of battery life. SOC is often estimated by the extended Kalman filter (EKF) algorithm, but this method depends on the accuracy of model parameters. The sampling point interval time can affect the accuracy of SOC estimation. In this paper, the first-order RC model parameters are identified by two methods and the SOC is estimated by the EKF algorithm. Using this method, the battery parameters are received more accurate and the SOC estimation error is smaller. When the sampling interval is 0.03 s, the SOC estimation error is the smallest. And the second-order RC model can receive the same result. When the sampling interval is 0.03 s, the SOC estimation error of the 1RC-1 method is less than 1.4 %, the SOC estimation error of the 1RC-2 method is less than 0.017, and the root mean square error (RMSE) is 0.0087 and 0.01084. The conclusion is also used in the second-order RC model and contributes to the improvement of the SOC estimation accuracy. An effective method to estimate the battery SOC range is also proposed. This paper provides an effective method for obtaining more accurate SOC. [ABSTRACT FROM AUTHOR]

This paper presents an exhaustive how-to guide on measuring the total vanadium concentration and state of charge of vanadium electrolytes using UV–Visible spectroscopy. The study is provided with an open-access database (GitHub) that supports the methods and procedures and facilitates access to the calibration data. The study covers the three types of electrolyte solutions relevant to vanadium redox flow batteries, namely the anolyte V II / V III , the catholyte V IV / V V , and the V III / V IV commercial electrolyte, meant to be preconditioned to either V III or V IV before battery operation. Analytical expressions to calculate the concentration of different vanadium species in the electrolyte solutions are provided based on either empirical correlations or spectral deconvolution methods. The paper also examines the limitations of the measurement technique and provides insightful recommendations for future research. The open-access database provided by the authors is expected to serve as a valuable repository for scholars and scientists working in the field of vanadium redox flow batteries. • UV–Visible spectroscopy is used to characterize vanadium electrolytes. • We studied the anolyte V II / V III , the catholyte V IV / V V , and V III / V IV . • An empirical method and a deconvolution method are proposed for each electrolyte. • The methods are calibrated over a wide range of concentrations (0.91–1.83M). • Total vanadium concentration and state of charge can be accurately measured. • Accuracy is 25–35 mM for the concentration and 1.0–1.5% for the state of charge. [ABSTRACT FROM AUTHOR]

• Different carbon-based electrodes following a nature-inspired solution were tested by CV and EIS. • Glass-carbon electrodes (GCE) and carbon paper-based electrodes (CPE) with and without polytetrafluoroethylene (PTFE) were evaluated. • The electrodes' performance was assessed by employing the ferri/ferrocyanide ([Fe(CN) 6 ]3-/4−) electrochemical probe. • Surface properties of the commercial electrodes materials were evidenced from AFM and water contact angle measurements. • Best results were achieved with CPE without PTFE, given its hierarchical porous structure and absence of the insulating binder. Carbon electrodes are widely accepted as very versatile platforms, with applications ranging from electrocatalysis to sensors and other devices, like fuel cells and water electrolyzers. However, there are still difficulties given that over time, at high potentials, the oxidation of carbon materials (as a catalyst and/or catalyst support) can play a detrimental role, undermining the efficiency and stability of the electrochemical processes and devices performance. In this paper, it is reported the research work followed by resourcing to electrochemical analytical techniques, like cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), along with complementary atomic force microscopy (AFM) and water contact angle (WCA) measurements. These techniques were used to characterise glass-type and paper-based carbon electrodes. On a nature-inspired solution, we took advantage of the different interfacial carbon-support hierarchical porous structures to boost the carbon electrocatalytic effect towards sensing the ferri/ferrocyanide redox couple ([Fe(CN) 6 ]3-/4−) in aqueous solution. It is shown that the best results were achieved with carbon paper electrodes without wet proofing, given its hierarchical porous structure and absence of the insulating binder. This research endeavors to contribute to the ongoing advancements in the field of electrochemical green energy conversion by exploring innovative approaches and materials, with the ultimate aim of developing carbon substrates that not only enhance performance but also promote environmental sustainability. [Display omitted] [ABSTRACT FROM AUTHOR]

• The basic model of high C-rate is determined by the model configuration analysis. • Sampling frequency and time domain influences model parameters are analyzed. • A model parameter correction method based on the rule of different overpotentials is proposed. • A modified high C-rate model is innovatively established with current dependence and concentration modification. • The modified model is validated up to the 6C rate at different temperature. The current battery equivalent circuit models are mainly suitable for room temperature or low C-rate conditions. However, the polarization phenomenon is serious at high C-rate, which results in the obvious voltage drop and significantly reduces the model accuracy at high C-rate. In this paper, the characteristics analysis of different RC models is firstly studied. It is found that the first-order RC circuit model is more suitable for high C-rate conditions due to the coupling of model parameter extraction. Based on the first-order RC model, a basic equivalent circuit model adapted to high C-rate condition is then determined. Secondly, the influences of sampling frequency and the identified time domain on instantaneous impedance and polarization resistance are researched. Thirdly, the change rules of different polarizations at high C-rate are analyzed. Furthermore, the relationship between the change rule of the model parameters and that of different overpotentials are researched. Subsequently, a modified high C-rate model is innovatively established, which considers the current dependence and concentration/temperature modification of instantaneous impedance and polarization resistance. Finally, the accuracy of the modified high C-rate model is verified at 5 °C, 25 °C, and 55 °C, respectively. Results show that the modified high C-rate model can improve the simulation accuracy of the voltage at high C-rate (≤6C), and the mean absolute error (MAE) and Root Mean Squared Error (RMSE) are within 68 mV. Compared with the existing high C-rate model, the accuracy of the modified high C-rate model proposed in this paper is improved and the complexity is also significantly reduced. [ABSTRACT FROM AUTHOR]

• The desired N(CH3)4V8O20 material, N(CH3)4+ of which exclusively acts as structural pillar, was firstly synthesized by facile one-step hydrothermal method and applied in AZIBs. • The N(CH3)4+ as structural pillar not only amplifies the interlayer spacing of 11.5 Å but also enhances structure stability, which actually optimizes the electrochemical performance overall. • The hierarchy distributive Zn anode grown on carbon paper with 3D braid architecture has proved effective. • It delivers a high capacity of 360 mAh g − 1 at 0.5 A g − 1 and capacity retention 97% after 5000 cycles at 50 A g − 1 with capacity of 105 mAh g − 1. Vanadate based cathode materials have been enormously investigated into aqueous zinc-ion batteries (AZIBs) in current research due to high specific capacity and large layer spacing that can accommodate sufficient ions. However, bulk vanadate based cathode materials suffer from a rapid capacity decaying as a result of low electronic conductivity, inferior ion diffusion kinetics and unstable structure during the zinc ion de/intercalation. Meanwhile, the inescapable zinc dendrite formation and reactive irreversibility during long cyclic testing also lead to growing polarization and poor cyclic performance. Herein, we put forward a strategy of structural design by synergistically introducing quaternary ammonium cation within vanadium bronze structure. The desired N(CH 3) 4 V 8 O 20 material, pure monomorph phase, was firstly synthesized by facile one-step hydrothermal method, which owns lattice spacing of 11.5 Å and stable crystalline structure for faster kinetics, higher capacity and better cyclic stability. Combined with the optimized 3D braid architecture of Zn@carbon paper anode, the as-obtained AZIBs exhibit a high capacity of 360 mAh g −1 at 0.5 A g −1. While the current density raises to 100 folds from 0.5 A g −1 to 50 A g −1, appreciable capacity of 105 mAh g −1 and outstanding stability of ultra-long lifespan with capacity retention 97% after 5000 cycles are achieved. Combining the sound investigations of experimental practices and computational research, mechanism of rapid and stable Zn2+ storage was systemically demonstrated. The optimized electrochemical performance could be attributed to highly reversible ion de/intercalation, superior ion diffusion kinetics and no side reactions. This work leads to a new strategy of the design for cathodes in AZIBs and unfolds a new path for the actualization of high-up vanadate based materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel hydrogen ion supercapattery was assembled. • N and P co-doped carbon paper was effectively acted as the cathode substrate. • The cyclic stability could be improved by modifying the cathode with Nafion. Hydrogen ion battery is a promising energy storage device due to its advantages of non-pollution, excellent rate capability and feasibility at low temperature. Herein, we assemble a novel rechargeable hydrogen ion supercapattery with the iodine-absorbed carbon paper doped with N and P (I 2 -NP-CP) as the cathode electrode and molybdenum trioxide as the anode electrode. Typically, the I 2 -NP-CP electrode shows the superior rate capability from 1 A g−1 (174.7 mAh g−1, 483.8 F g−1) to 20 A g−1 (111.1 mAh g−1, 307.7 F g−1), mainly ascribed to the strong interaction between iodine and the NP-CP substrate. Furthermore, electrochemical measurement of the I 2 -NP-CP@Nafion//MoO 3 supercapattery manifests that the electrodes exhibit excellent cycling stability, retaining 124.3 mAh g−1 after 500 cycles at 15 A g−1, accounting for 93.2 % of the initial capacity. Although some IO 3 − dissolves in the electrolyte due to the weak chemical interaction between IO 3 − and NP-CP, and cannot be completely reduced to I− during discharge process, it can be improved by modification of electrode with Nafion resin to further better the cycling stability. The excellent electrochemical properties in this study show the possibility for the development of novel rechargeable hydrogen ion supercapattery system. [Display omitted] [ABSTRACT FROM AUTHOR]

• The novel solution route based on metal-organic decomposition (MOD) process is successfully developed for a facile preparation of CoFe 2 O 4. • The effect of cation distribution on the OER activity in CoFe 2 O 4 is elucidated with emphasis placed on the structure–property relationship. • A cation redistribution in octahedral and tetrahedral sites within the spinel structure leads to the enhancement in hole density and concomitant OER activity. • The CoFe 2 O 4 integrated on carbon fiber paper (CFP) exhibits high electrocatalytic performance. • An overpotential (η 10) of 359 mV at 10 mA cm−2 and a Tafel slope of 53.8 mV dec−1 are obtained for the electrocatalyst in 1 M KOH aqueous solution. The novel solution route based on metal-organic decomposition (MOD) process is successfully developed for a facile preparation of CoFe 2 O 4. The electrocatalytic activity of CoFe 2 O 4 for the oxygen evolution reaction (OER) of electrochemical water splitting is investigated as a function of calcination temperature in the range between 300 and 450 °C. It is significantly found that a drastic cation redistribution in octahedral and tetrahedral sites within the spinel structure of 450 °C-calcinated CoFe 2 O 4 p-type semiconductor leads to the dramatic enhancement in hole density and concomitant OER activity. The CoFe 2 O 4 integrated on carbon fiber paper (CFP) exhibits high electrocatalytic performance, including an overpotential (η 10) of 359 mV at10 mA cm−2 and a Tafel slope of 53.8 mV dec−1 in 1 M KOH aqueous solution. Based on this work, a design principle of the MOD solution process developed can be applied to preparation of a greater variety of compounds. Also, elucidation of structure-OER activity relationships in spinel-type CoFe 2 O 4 electrocatalysts will be able to advance further. [Display omitted] [ABSTRACT FROM AUTHOR]

A facile and sustainable electrochemical synthetic strategy for phenyl benzimidazoles has been developed using a ferrocene-based electrocatalyst anchored on Toray carbon paper (TCP) coated with conducting polymeric film. The developed electrode was used for the electrochemical dehydrogenative cyclization reaction of o -phenylene diamine and benzaldehyde using lithium perchlorate/acetonitrile as electrolyte. The surface characteristic properties of the developed electrode were characterized by FESEM, Optical profilometer and X-ray photoelectron spectroscopy. Electron transfer mechanism of the anchored ferrocene-based electrocatalyst was thoroughly studied. To determine the efficacy of the catalyst, the electron transfer coefficient (0.5) and apparent rate constant 41.4 s−1 were determined. The cyclic voltammetry studies reveal that the electrochemical oxidation peak for the synthesis of benzimidazole occurs at 0.48 V. The formation of the product was confirmed by Gas chromatography and Nuclear Magnetic Resonance spectroscopy. A comparison chart is presented for the green metrics and sustainability of the present strategy with other electrochemical approach. [Display omitted] [ABSTRACT FROM AUTHOR]

Two-dimensional nanolayered Mo 2 CT x is an excellent electrode material due to its large surface area and high conductivity. In this paper, Mo 2 C powders and metal Ga with the molar ratio of 1:3 as raw materials were used to prepare phase-pure Mo 2 Ga 2 C ceramic materials by non-pressure sintering at 750 °C, and two-dimensional nano-layered Mo 2 CT x materials were etched successfully using a facile oil bath method by HF. Capacitive behaviors of flexible and freestanding Mo 2 CT x film electrode prepared by the facile vacuum filtration in 1 M H 2 SO 4 , 1 M Na 2 SO 4 and 1 M NaOH electrolytes were systematically investigated for the first time. Mo 2 CT x film electrode exhibits the pseudo-capacitive behavior in H 2 SO 4 electrolyte, while double layer capacitance is presented in Na 2 SO 4 and NaOH electrolytes. The maximum volumetric specific capacitance of 563.05 F/cm3 at 2 mV/s is in H 2 SO 4 electrolyte, corresponding to the mass specific capacitance of 154.26 F/g. This is due to the obvious redox reaction in sulfuric acid solution Notably, density functional theory (DFT) calculation was executed to investigate the capacitive behavior and mechanism of the Mo 2 CT x film electrode in the three different electrolytes. [ABSTRACT FROM AUTHOR]

• Synthesis of MIL-100 (Fe) from Fe(OH) 3 slag from hydrometallurgy. • Porous structure improves the rate-multiplying performance of PIBs. • The porous structure improves the K+ migration reaction kinetics. • Incomplete coordination leads to higher carbon content. Recycling spent cathode materials is crucial for sustainably developing lithium-ion battery technology. To achieve the high-value utilization of spent LiFePO 4 (LFP) cathodes, this paper proposes a method for preparing MIL-100(Fe) based on solid waste residues from spent LFP cathodes. R-FeS 2 @C derived from MIL-100(Fe) can serve as an anode material for potassium-ion batteries featuring a porous structure. Electrochemical tests demonstrate that the R-FeS 2 @C exhibits more stable cycling performance compared with the FeS 2 @C derived from the traditional MIL-100(Fe), reaching 525 mAh g−1 after 100 cycles at a current density of 100 mA g−1. Impressively, R-FeS 2 @C also showcases excellent rate performance (343 mAh g−1 specific capacity at 5 A g−1). Furthermore, full cells assembled with PI@rGO cathodes also exhibit excellent rate performance and stable cycling performance. The porous structure of R-FeS 2 @C provides numerous voids to accommodate volume changes and introduces sufficient channels for electrolyte penetration. The higher carbon content enhances the electrical conductivity improving the kinetics of the K+ migration reaction. These researches can provide guidance for the recycling of spent lithium-ion batteries and the design of sulfide electrodes for PIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

• A heterostructure consisting of Co@NC and NiMo-LDH was achieved. • Electron coupling in heterogeneous structures accelerates the electron transport rate. • The DFT results confirm the synergetic effect between the Co@NC and NiMo-LDH. • The assembled Zn-air battery exhibit a high paek density of 210 mW cm-2. It remains an urgent task to design electrocatalysts with fast oxygen evolution reaction (OER) kinetics and enriched active sites for flexible Zn-air batteries. In this paper, a structure engineering strategy is proposed to design an electrocatalyst with a heterostructure comprising Co@NC and NiMo-LDH on carbon cloth, which serves as an air electrode for a quasi-solid-state Zn-air battery. This unique heterostructure significantly enhances electrocatalytic activity, producing low OER overpotentials of 198 mV at 10 mA cm-2. Moreover, the assembled rechargeable Zn-air battery exhibits a high peak density and long cycle stability. Density functional theory calculations indicate that the multimetallic heterostructure induced synergistic and electronic coupling effects among the metal active sites, facilitating rapid ion and electron transport during the OER process. In addition, the migration of oxygen species at the Ni and Mo sites reduces the reaction potential barrier, resulting in a low OER overpotential of 160 mV. The construction of multi-metallic heterostructures enables optimisation of the electronic environment around the active sites and synergistic enhancement of the OER activity, leading to high performance quasi-solid-state Zn-air batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, (NH 4) 2 V 4 O 9 nanosheets coexisting with carbon nanotubes were prepared by hydrothermal method as cathode materials for aqueous zinc ions, which can improve the electrochemical performance of the battery. The structure, morphology and electrochemical properties of (NH 4) 2 V 4 O 9 /CNTs were studied and analyzed by physical characterization and electrochemical tests. Carbon nanotubes coexisting with (NH 4) 2 V 4 O 9 provide an electron transfer channel, significantly improving the rate performance of the material. The discharge specific capacity of (NH 4) 2 V 4 O 9 /CNTs is 445 mAh g −1 at a current of 0.1 A g −1; while the discharge specific capacity still remains 207.16 mAh g −1 when the current up to 5.0 A g −1. After 2000 cycles at a high current density of 10 A g −1, the discharge specific capacity of the battery remained 93.1 mAh g −1 from 115.2 mAh g −1 in the first cycle, showing good cycle performance. Therefore, (NH 4) 2 V 4 O 9 /CNTs has fast charge-discharge performance and cycle stability. [ABSTRACT FROM AUTHOR]

Silicon (Si) and silicon monoxide (SiO) have attracted great interest as next-generation anode materials for lithium-ion batteries (LiBs) due to their high energy density. However, their commercialization has been hindered by rapid capacity fading, which stems from mechanical degradation (e.g., cracking and delamination) and the aggressive formation of solid electrolyte interphase (SEI) layer. While understanding these degradation mechanisms in batteries necessitates in-operando measurement techniques, very few non-destructive analytical methods have been documented in literature. This paper highlights the effectiveness of combined electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) techniques in performing systematic characterization of LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC)/nano-Si and NMC/micro-SiO full-cells. The systematic design of experiments enabled the separate deconvolution of anode and cathode aging using symmetrical cells. This approach offered a clear understanding of the overall degradation mechanisms in the full-cells. The major impedance sources in the NMC/nano-Si full-cell were anode contact impedance, resulting from mechanical degradation of Si, and cathode charge transfer impedance, due to significant lithium loss and consequently deeper extraction of lithium ions in NMC. In contrast, micro-SiO anodes exhibited less electrode-level degradation, as evidenced by SEM images and relatively stable impedance behaviors during extended cycling, which strongly corroborate its superior capacity retention (66 % at 300th cycle) compared to that of nano-Si anode in full-cells (26.5 % at 300th cycle). [ABSTRACT FROM AUTHOR]