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State of charge (SOC) is a critical metric for assessing the remaining capacity of lithium-ion batteries, while convergence time is an essential indicator for evaluating the performance of SOC estimation. To reduce the convergence time of SOC estimation, a novel strategy has been proposed. Initially, an accurate and comprehensive model is employed for lithium-ion batteries, which includes the nonlinear behavior of the open circuit voltage (OCV) with respect to SOC. However, the linear component of this model is unobservable. Then, the nonlinear relationship between OCV and SOC is approximated using a first-order piecewise fitting function. This approach ensures accuracy while reducing computational complexity compared to non-linearization methods. Next, the unobservable model is decomposed into observable and unobservable subsystems, addressing the challenge of designing observers for unobservable models. Furthermore, a finite time observer is designed based on the observable subsystem, enabling SOC estimation to be achieved within any pre-set convergence time. Finally, theoretical analysis and extensive experimental results validate the feasibility and reliability of the proposed estimation strategy, demonstrating its superiority over traditional methods. [ABSTRACT FROM AUTHOR]

We fabricated a photo-driven bioanode on laser-induced graphene (LIG) using a facile one-step laser-scribed technique. Nb 4 C 3 T x MXene was decorated on the LIG surface to induce a high surface area for immobilizing the photocatalyst. The thylakoid membrane extracted from Spinacia oleracea utilizes its intrinsic photosynthetic and catalytic capability for efficient energy conversion. A platinum-based gas diffusion electrode is used as the cathode material, allowing for charge transfer and oxygen reduction to produce water. The bioelectrochemical activities of the as-fabricated thylakoid-based biofuel cells were investigated. Upon illumination, the assembled biofuel cell exhibited an open circuit voltage of 0.45 V, a maximum photocurrent density of 68.69 µA/cm2, and a power density of 7.24 µW/cm2. The unique features of thylakoid membranes, Nb 4 C 3 T x MXene, and the LIG substrate play a critical role in producing high-performance photo-biofuel cells. Our approach presents a promising strategy for harnessing the biochemical energy of plants to generate bioelectricity. [ABSTRACT FROM AUTHOR]

Improving the lifetime and robustness of solid oxide fuel cells (SOFCs) is crucial for their commercial viability. This study aims to elucidate the degradation mechanism of SOFCs during galvanostatic tests and understand the internal and external factors influencing the cell degradation. Three nominally identical cells underwent galvanostatic testing for different durations to illustrate the evolution mechanism of SOFCs degradation at different stages. The electrochemical impedance spectroscopy (EIS) measurements under the open circuit voltage (OCV) and the direct current (DC) bias at different periods were carefully analyzed. By combining distribution of relaxation times (DRT) with equivalent circuit model (ECM) fitting, the contribution of each electrode process to cell performance degradation during galvanostatic testing was quantified. The polarization impedance, primarily associated with the charge transfer reactions in the anode, exhibited continuous increase under DC bias, contributing more than 80 % to the increase overall polarization impedance. Conversely, the cathode, related to O 2 dissociation and diffusion process, contributed 7.2 %. The rapid degradation in the early stage was attributed to the degeneration of the anode microstructure, resulting from the formation of numerous isolated micron Ni particles and a subsequent decrease in three phase boundary (TPB) density. The anode microstructure after galvanostatic testing was characterized, revealing a novel Ni migration evolution mechanism. This mechanism involves the rapid agglomeration of Ni crystal particles at the beginning test, subsequent diffusion as micro-particles within 25 h, and eventual coarsening into dispersive agglomerates over time. The proposed mechanism of anodic microstructure evolution offers insights for optimizing anodic structures and lays the foundation for enhancing the long-term stability of SOFCs. [ABSTRACT FROM AUTHOR]

The highly effective and economical electrocatalysts hold great importance in the context of water electrolysis. In this work, a nanosheet catalyst (Ni 3 FeN/NF) composed of nanoparticles for comprehensive water splitting was synthesized through a facile hydrothermal technique followed by a subsequent nitridation process. This catalyst is endowed with an abundance of oxygen vacancies, thereby conferring a richer array of active sites. Therefore, the catalyst demonstrates a markedly low overpotential for the OER of 271 mV at 50 mA cm−2 and an equally low overpotential for the HER of 35 mV at 10 mA cm−2. Serving as a dual-function electrode, this electrocatalyst is employed in overall water splitting in alkaline environments, demonstrating impressive efficiency of 10 mA cm−2 at a cell voltage of 1.45 V. In-situ Raman spectroscopy was employed to elucidate the active phase and dynamic surface structure of the Ni 3 FeN/NF catalyst by conducting measurements at intervals of 0.1 V. At open circuit voltage (OCV), Ni 3 FeN/NF exhibited pronounced peaks at 532 and 702 cm−1. Notably, at potentials exceeding 1.40 V, distinct peaks were observed at 473 and 551 cm−1. The manifestation of these dual peaks indicates that γ-Ni(Fe)OOH serves as the predominant active species in the oxygen evolution reaction (OER) mechanism for Ni 3 FeN/NF. [Display omitted] [ABSTRACT FROM AUTHOR]

Inorganic light harvesting materials are revolutionising the current research scope of quantum dot-sensitized solar cells (QDSSCs) day by day. However, it is challenging due to the issues in toxicity and stability of existing light-harvesting materials. Herein, we present highly stable non-toxic bismuth trisulfide (Bi 2 S 3) QDSSCs with iodide/triiodide redox electrolyte. The solar cell is configured as FTO/TiO 2 P90/TiO 2 P25/Bi 2 S 3 /(I-/I- 3) electrolyte/Pt. Bi 2 S 3 quantum dots (QDs) were fabricated onto the FTO/TiO 2 P90/TiO 2 P25 electrode at room temperature using the dip-successive ionic layer adsorption reaction (Dip-SILAR), which is an easy and efficient technique. Electron microscopy confirmed that the quantum dots formed uniformly on the photoanode, with sizes ranging from 50 nm to 80 nm. QDSSCs with an active cell area of 0.16 cm2 were characterized under an illumination of 100 mW cm-2 with AM 1.5 spectral filter and the results depicted that the best cell acquired a power conversion efficiency of 0.26 % with an open circuit voltage (V oc) of 482.9 mV and short circuit current density (J sc) of 1.05 mA cm-2. To enhance the stability, polyvinylpyrrolidone (PVP) based gel polymer electrolyte has been used. The high cost of conventional light harvesting materials may be significantly reduced by one-step fabrication of Bi 2 S 3 using the SILAR technique. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon is a frequently used active material in the negative electrode of lithium-ion batteries which provides significant improvements in the energy density. Due to large volume changes during cycling, it is typically mixed with graphite. Understanding the interactions of composite materials during battery operation is key to optimizing battery performance and predicting aging phenomena. Even though lithium plating is a critical degradation process, which influences both lifetime and safety, a systematic analysis of electrochemical material parameters affecting plating in composite electrodes is missing. Therefore, a parameter study is performed using 3D microstructure-resolved simulations. We investigate the influence of critical material parameters such as open-circuit potential, electronic conductivity, chemical diffusion coefficient, and exchange current density in simple and interpretable model geometries. The simulations reveal the importance of chemical diffusion and exchange current density, as well as their ratio, in predicting plating. Finally, we apply the set of material parameters to a complex electrode geometry reconstructed from FIB/SEM tomography data of commercial anode material. The analysis shows that preferential plating on the electrode surface dominates all other factors. [Display omitted] [ABSTRACT FROM AUTHOR]

• The evolution of EIS of zinc-rich coatings is explained in detail. • The corrosion product layer causes the shielding effect of zinc-rich coatings. • Semi-logarithmic relationships suggest that t1/2 axis is useful for impedance studies. • Linear correlations help in designing equivalent circuits (EE). • Linear correlations help in elucidating the physical meaning of EE components. This paper focuses on elucidating the variation rules of equivalent circuit elements of electrochemical impedance spectra (EIS) of two different thicknesses of epoxy zinc-rich coatings (EZRCs) and silicate ethyl zinc-rich coatings (ZRCs). The correlation between the circuit elements and the low-frequency impedance modulus (|Z| 0.01 Hz) and the open-circuit potential (OCP) is investigated, and an explanation of the barrier effect and the evolution law of corrosion potential (E corr) is given. The results show that there is a linear or piecewise linear relationship between the logarithm of |Z| 0.01 Hz and the circuit elements with a square root of time (t1/2), and the piecewise linear relationship between the OCP and t1/2. Further, there is a large amount of linear correlation between circuit elements. The semi-logarithmic linear relationship suggests that the square root axis can be a conventional choice for coating impedance studies. Linear correlations help in designing equivalent circuits and elucidating the physical significance of components in equivalent circuits. The barrier effect of ZRCs mainly refers to the blocking effect of the corrosion product layer on the outer surface of the coating. The barrier effect of ZRCs can be neglected. Designing equivalent circuits: location of circuit elements and current assignments, fitting accuracy, trends in model parameters, linear correlation of elements. [Display omitted] [ABSTRACT FROM AUTHOR]

The annual generation of coffee waste has overtaken 6 million metric tons, becoming a serious environmental problem. Herein, we report the fabrication of bimetallic electrocatalysts synthesized by 1) pyrolyzing spent coffee grounds (SCGs) at 400, 600, 800 and 1000 °C, 2) activating the as-obtained char with KOH and 3) functionalizing the activated carbon with iron(II) and manganese(II) phthalocyanine. The final electrocatalysts showed a high degree of amorphousness, defectivity (increasing with temperature) and high specific surface area (up to 1820 m2 g−1). In half-cell compartment (0.1 M KOH electrolyte), the top-notch material in terms of oxygen reduction reaction (ORR) activity and selectivity was CFeMn_600, which showed the same half-wave potential (E 1/2) compared to Pt/C standard along with a lower peroxide production. These outstanding results could be attributed to a high surface area, a Fe-Mn synergy, and an abundance of C-N defects. The performance of CFeMn_600 as a cathode material in alkaline exchange membrane fuel cells (AEMFC) showed an open circuit voltage (OCV) of 0.890 V and power density of 30 mW cm−2. Notwithstanding, this research is one of few cases where a waste-derived electrocatalyst is tested in a real AEMFC, thus becoming a pioneer in the fuel cell study of waste-derived electrode materials. [ABSTRACT FROM AUTHOR]

Compositionally tuned nickel-cobalt layered double hydroxides (NCLDHs) and NCLDH@reduced graphene-oxide (NCLDH@rGO) were synthesized through a facile solvothermal synthesis route. The formation of the synthesized NCLDH and the NCLDH@rGO with the intercalated carbonate and nitrate anions, has been confirmed utilizing different characterization techniques. Microscopic results revealed the flaky morphology with thickness about 30 nm. Rotating ring disc electrode (RRDE) voltammetry was utilized to analyze the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and carbon dioxide reduction reaction (CO 2 RR) kinetics on each of the pristine (1:1), (2:1), (3:1) and (4:1) NCLDH catalysts and the NCLDH@rGO composites. The RRDE data revealed that the electrochemical activity towards ORR/OER/CO 2 RR could be largely increased by tuning mole ratio of the (Ni2+/Co3+) or the amount of the rGO in the NCLDH. It turned out that among the pristine electrocatalysts, the (1:1) NCLDH catalyst exhibited enhanced ORR/OER kinetics. While the NCLDH acted as a catalyst center, the rGO provided conductive network that facilitated passable overpotential with increased current density for the ORR/OER/ CO 2 RR. Better adsorption of O 2 and CO 2 on the NCLDH@rGO catalyst also contributed for the electrocatalytic activity. Consequently, the NCLDH@rGO composites as cathode catalyst for Li-O 2 battery in the CR2032 prototype coin-cell exhibited a stable open circuit voltage (OCV). Among the NCLDH@rGO composites, the NCLDH with 15 wt.% rGO (NCRGO15) exhibited a high discharge capacity of 3616 mAh g −1 at 50 Ag−1 for the Li-O 2 battery and a discharge capacity of 45 mAh g −1 at a current density of 100 Ag−1 for the CR2032 coin-type Li-CO 2 battery. As a practical use, a commercial 2.8 V green LED bulb was lit continuously for about 20 h using the fabricated Li-O 2 battery that consisted of lithium anode and (1:1) NCLDH@rGO15 wt.% (NCRGO15) air-breathing cathode. [ABSTRACT FROM AUTHOR]

• CO 2 electroreduction activity of Ni-Co and Ni-Cu infiltrated cathodes was tested. • Electrochemical performance of SOECs was studied from 750 to 850 °C. • Co infiltrated cathodes showed the best CO 2 electroreduction performance. • SOECs with Co, Ni, and Ni-Co infiltrated cathodes had stable long-term performance. This study evaluates the electrochemical performance of Gd 0.1 Ce 0.9 O 1.95 (GDC10) cathodes infiltrated with bimetallic Ni-Co and Ni-Cu alloy electrocatalysts for CO 2 electroreduction in solid oxide electrolyzer cells (SOECs). The electrochemical reduction performance of SOECs with cathodes infiltrated with Ni-Co and Ni-Cu alloys was compared to the performance of SOECs having cathodes infiltrated with Ni, Co, and Cu. Electrochemical performance was evaluated at 750, 800, and 850 °C. Cells with Co, Ni 0.50 Co 0.50 , Ni 0.75 Co 0.25 , and Ni infiltrated cathodes displayed relatively similar CO 2 electroreduction performance; however, SOECs having Co infiltrated cathodes had slightly better catalytic performance towards CO 2 reduction as demonstrated by their lower polarization resistance (R p) values of 8.54, 4.03, and 1.25 Ω·cm2 when measured under open circuit voltage (OCV) at 750, 800, and 850 °C, respectively. Cells having Co, Ni 0.50 Co 0.50 , Ni 0.75 Co 0.25 , and Ni infiltrated cathodes showed a stable long-term CO 2 electroreduction performance with Faradaic efficiency values approaching 100 % when tested under 0.20 A·cm−2 for 48 h and at 750 °C. Results indicate that SOECs with Ni infiltrated cathodes possessed better short- and long-term CO 2 electroreduction performance compared to SOECs featuring cathodes infiltrated with Cu, Ni 0.25 Cu 0.75 , and Ni 0.50 Cu 0.50. Increasing Ni percentage within the Ni-Cu alloy structure had a positive impact on the electrochemical performance as cells with Ni 0.50 Cu 0.50 infiltrated cathodes showed relatively close voltage values to those of cells with Ni infiltrated cathodes during short-term galvanostatic tests. Although the SOEC with Ni 0.50 Cu 0.50 infiltrated cathode experienced performance degradation throughout the long-term test period, it demonstrated better electroreduction performance having Faradaic efficiency values approaching 100 % compared to cells with Cu and Ni 0.25 Cu 0.75 infiltrated cathodes when evaluated under 0.20 A·cm−2 for 48 h and at 750 °C. [ABSTRACT FROM AUTHOR]

Internal hydrogen leakage faults in fuel cells can cause severe performance loss and safety risks. The aim of this study is to achieve qualitative and quantitative diagnoses of internal leakage in fuel cell based on air flowrate control and transient voltage measurements. The hydrogen crossover characteristics of a fault-free and defective fuel cell are both investigated, and the effectiveness of the diagnosis method is evaluated by comparing and analyzing the results before and after the leakage fault introduction. The results suggest that hydrogen leakage failure inside fuel cell is dominated by convection processes. In airflow interruption tests, where the fuel cell is operated under open-circuit conditions with given anode overpressures, the fall time of the cell voltage is used as a qualitative measure of internal hydrogen leakage, and fault occurrence can be recognized by a considerable decrease in this indicator. Through cyclic staircase flowrate sweep tests, we obtain good estimates of internal leakage rates in the defective fuel cell. These diagnostic methods can be performed directly under hydrogen/air conditions, and there is no need for additional power source equipment dedicated to generating excitation signals for fuel cell, giving them great potential in on-board applications. [ABSTRACT FROM AUTHOR]

• Single-atom Pd/WO 2.72 is first prepared and used as a bifunctional electrocatalyst. • Pd atom is anchored to O atom in WO 2.72 to form stable single-atom structure. • The 5 %Pd/WO 2.72 shows excellent bifunctional electrocatalytic behaviors. • The assembled 5 %Pd/WO 2.72 zinc-air battery has good electrocatalytic performances. Searching for an excellent bifunctional electrocatalyst used in zinc-air batteries (ZABs) is a long-term and challenging task. Single-atom catalysts have been becoming potential bifunctional electrocatalysts because of their maximum metal atom utilization and low content of metal itself. Herein, noble metal palladium (Pd) is uniformly anchored in the supported WO 2.72 to form single-atom Pd/WO 2.72 owing to the special 4d orbit of Pd and nonstoichiometric 2D planar structure of WO 2.72. Single-atom 5 % Pd/WO 2.72 is prepared in this work, showing excellent bifunctional electrocatalytic behaviors with high E 1/2 of 0.86 V for ORR and low E j= 10 of 1.59 V for OER in alkaline medium, and the ∆E is 0.73 V, which outperforms the Pt/C and RuO 2. Furthermore, the 5 % Pd/WO 2.72 -ZAB has a high open-circuit voltage (OCV) value of 1.491 V, a large power density of 168 mW cm−2, and a large specific capacity of 633 mAh g−1. Besides, the 5 % Pd/WO 2.72 -ZAB also has good cycling stability. [ABSTRACT FROM AUTHOR]

By compositing cerium oxide (Gd 0.1 Ce 0.9 O 1.95 , GDC) with the dysprosium-zirconium co-doped bismuth oxide (Dy 0.2 Zr 0.05 Bi 0.75) 2 O 3 , or DZSB, a novel DZSB-GDC composite electrolyte is developed, which has excellent sintering ability and ionic conductivity. Reverse coprecipitation is used to prepare nano composite electrolyte powders, and the sintering and electrical properties with varying DZSB composite ratio are examined. After sintered at 1200 °C for 10 h, all composite electrolyte pellets can achieve densities of more than 95 %. Furthermore, as the DZSB ratio increases, the densification rate increases and the starting temperature of the densification stage decreases. 10DZSB-GDC shows the highest conductivity (σ t) and has an activation energy of 0.92 eV below 550 °C, which is 8.9 % lower than that of pure GDC. At 400 °C, the grain boundary conductivity of 10DZSB-GDC was 113.8 times that of pure GDC. The ionic conductivity of 10DZSB-GDC remain stable at 0.015 S cm−1 at 600 °C for 4200 h without any decay. The open-circuit voltage and peak power density of 10DZSB-GDC based cell are 0.914 V, and 441.1 mW cm−2 at 750 °C, which is 1.1 and 2.1 times that of GDC-supported cells, respectively. This indicates that 10DZSB-GDC is a promising electrolyte material for low-temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

Photo-chargeable supercapacitors are attracting significant research interest as promising alternative to energy storage devices suitable for next-generation smart appliances. In this work, a heterojunction of cadmium sulphide (CdS) nanoparticles and zinc oxide (ZnO) nanorods is obtained for designing a broadband photo responsive symmetrical supercapacitor. Ultraviolet (UV) absorption by ZnO and visible light interaction with the CdS nanoparticles in the heterostructure contribute synergistically to deliver UV to visible broad spectral response. The heterojunction formation is confirmed by field effect scanning electron microscopy and high-resolution transmission electron microscopy with elemental mapping. Areal capacitance was measured in both the dark and under illumination conditions using cyclic voltammetry and galvanostatic charge–discharge, supported by impedance spectroscopy. Enhancement of areal capacitance from the dark condition was observed between ∼238% to ∼1264% for different illumination in broad spectral range measured from the cyclic voltammetry measurements at a constant scan rate of 50 mV s−1 and achieved a highest capacitance value of ∼139 µF cm−2 under 475 nm visible light for the scan rate of 10 mV s−1. Moreover, the charge generation and storage mechanism under illumination were verified by phototransient response and open-circuit potential measurements. The excellent electrochemical performance observed by maintaining high efficiency (∼94.7%) with improved cyclic stability upto 5000 cycles. A good capacitance retention (∼90%) in bending mode when heterojunction applied in bendable devices provide broad future prospect for the metal oxide-sulphide interface in photo-chargeable smart devices. [ABSTRACT FROM AUTHOR]

Inverted planar heterojunction solar cells (iPHSCs) were fabricated with novel spiro-bifluorene (CF-Sp-BTh) based hole transport material (HTM) and graphene oxide (GO) modified perovskite (CH 3 NH 3 PbI 3) as sensitizer. CF-Sp-BTh exhibited relatively high hole mobility and favorable HOMO level with respect to the valence band of CH 3 NH 3 PbI 3. iPHSC using CF-Sp-BTh HTM and GO (0.5 wt%)-CH 3 NH 3 PbI 3 achieved the power conversion efficiency (PCE) of ∼14.28%, with open circuit voltage (V OC) of ∼1.07 V and a short circuit current density (J SC) of ∼18.82 mA/cm2. The photovoltaic performance of FTO/CF-Sp-BTh/GO (0.5 wt%)-CH 3 NH 3 PbI 3 /PC 61 BM/Au was higher compared to pristine CH 3 NH 3 PbI 3 and other GO-CH 3 NH 3 PbI 3 hybrid based devices. The photoluminescence decay and electrochemical impedance spectra confirmed an enhanced charge separation and retarded charge recombination of GO-CH 3 NH 3 PbI 3 hybrid based iPHSCs. [ABSTRACT FROM AUTHOR]

We demonstrated an organic-inorganic composite as hole transport layer consisting of water-free PEDOT:PSS and tungsten oxide (WO 3) nanoparticles, which enhanced the power conversion efficiency of normal-structure perovskite solar cells (PSCs). The PSC employing the WO 3 /PEDOT:PSS film as a hole transport layer exhibited better device stability and improved power conversion efficiency (PCE) with approximately 20% performance enhancement. The highest PCE obtained from WO 3 /PEDOT:PSS device was 15.1%, owing to simultaneous increments on short circuit current, open circuit voltage and fill factor. WO 3 nanoparticles can fill out the pinholes of porous PEDOT:PSS layer, demonstrating a void-free and homogenous HTL surface. WO 3 /PEDOT:PSS composite demonstrated much higher charge conductivity and hole mobility than pristine PEDOT:PSS layer. The interface of perovskite absorber and WO 3 /PEDOT:PSS HTL also contained less defect density. The superior performance of WO 3 /PEDOT:PSS composite was attributed to the reduced current leakage, enhanced hole extraction characteristics, and less trap-assisted interfacial recombination via current density - voltage, electron microscopy (SEM, AFM and c-AFM), electrochemical impedance spectroscopy (EIS) and space-charge limited current–voltage (SCLC) measurements and analysis. Image 1 [ABSTRACT FROM AUTHOR]

Abstract The problem remains unsolved in DMFCs applications that the increase in proton conductivity is usually caused the permeation of methanol. Herein, a novel kind of pore-filling membrane is investigated to meet this challenge. The porous substrate is fabricated from block poly (ether sulphone) with low degree of sulfonation, which form well-developed conductive channels owing to an aggregation of sulfonic acid groups, ensuring low methonal crossover and swelling ratio. The pore structures are achieved by a solution casting method which introduces alpha-cyclodextrin as the porogen. The resulting porous substrate possesses homogeneous opening pore structures. Then, the filling electrolyte, an organic-soluble tetrabutylammonium 4-vinylbenzene sulfonate, is used to fill the substrate and form a crosslinked network inside the pores to ensure high proton conductivity. The pore-filling membrane with block polymers shows higher proton conductivity (0.083 S cm−1 at 80 °C) than that prepared by random polymers (0.072 S cm−1 at 80 °C). Compared with Nafion 117, the composite membrane exhibits higher dimensional stability (6.6%) and methanol resistance (4.0 × 10−7 cm2 s−1). Furthermore, the pore-filling membrane outperforms Nafion 117 with an open circuit voltage of 0.61 V as well as a maximum power density of 46.8 mW/cm2 under 10 M methanol condition. Graphical abstract Image 1 Highlights • Novel CSPS filled SPES pore-filling proton exchange membrane. • Porous substrate based on block sulfonated copolymers enhanced proton conductivity. • Significant suppression of methanol crossover over pore-filling membranes. • Single cell performance outperformed Nafion 117 in 10 M methanol. [ABSTRACT FROM AUTHOR]

Abstract Graphene possesses excellent mechanical strength and chemical inertness with high intrinsic carrier mobility and superior flexibility making them exceptional candidates for optoelectronic applications. Graphene quantum dots (GQDs) derived from graphene domains have been widely explored to study their photoluminescence properties which can be tuned by size. GQDs are biocompatible, low cytotoxic, strongly luminescent and disperse well in polar and non-polar solvents showing bright promise for the integration into devices for bioimaging, light emitting and photovoltaic applications. In the present study, graphene quantum dots were synthesized by an electrochemical cyclic voltammetry technique using reduced graphene oxide (rGO). GQDs have been incorporated into binder free TiO 2 paste and studied as a photoelectrode material fabricated on ITO/PEN substrates for flexible dye sensitised solar cells (DSSCs). DSSC based on GQDs-TiO 2 exhibited open circuit output potential difference (V oc) of 0.73 V, and short circuit current density (J sc) of 11.54 mA cm−2 with an increment in power conversion efficiency by 5.48%, when compared with those with DSSC build with just a TiO 2 photoanode (open-circuit output potential difference (V oc) of 0.68 V and short circuit density (J sc) of 10.67 mA cm−2). The results have been understood in terms of increased charge extraction and reduced recombination losses upon GQDs incorporation. Graphical abstract Image 10376 Highlights • GQDs were prepared by electrochemical cyclic voltammetry technique using reduced graphene oxide as starting precursor. • GQDs-TiO 2 films are prepared by doctor blade method. • The GQDs-TiO 2 based flexible polymer DSSC exhibited good photo conversion parameters. • Further modification in the GQDs-TiO 2 film preparation can lead GQDs as a promising material in hybrid photovoltaics. [ABSTRACT FROM AUTHOR]

Abstract Four isomeric organic dyes featuring D-A′-π-A configuration with 5-methylbenzothiadiazole as auxiliary acceptor have been synthesized and characterized as sensitizer for dye-sensitized solar cell. The dyes with methyl unit attached near donor exhibited high molar extinction coefficients when compared to the isomeric dyes possessing methyl unit near acceptor segment. Due to this, the former dyes exhibited two fold high power conversion efficiencies when compared to the later dyes. The high efficiency of the dyes containing methyl near donor arises from the enhanced photocurrent density and open-circuit voltage values. The electrochemical impedance spectra demonstrated favourable electron injection, longer electron lifetime and effective charge recombination resistance for dye-sensitized solar cells based on these dyes. The attenuation in the coplanarity between the donor and acceptor with benzothiadiazole due to the presence of methyl group significantly affected the donor-acceptor interactions and charge migration kinetics. Graphical abstract Image 1 Highlights • Isomeric organic dyes containing methylbenzothiadiazole are designed and synthesized. • The position of methyl groups alter the donor-acceptor interactions and charge transfer transition. • Dyes containing methyl group near donor exhibited relatively high molar extinction coefficients. • The variation in charge transfer resistance and charge recombination resistance revealed interesting role of methyl group. [ABSTRACT FROM AUTHOR]

Abstract The state-of-charge (SOC) estimation method currently ignores the measurement error caused by the Battery Management System (BMS). In this paper, the characteristic of LiFePO 4 battery is deeply studied to explore the relationship between open-circuit-voltage (OCV) and SOC. By the analysis of the characteristic of the curve, the results show that the curve does not change with the battery aging by the capacity correction. Meanwhile, the feature of the charging voltage curve is also analyzed. It is pointed out that the ohmic internal resistance and capacity can be obtained by the transformation of the charging voltage curve, which reduces the workload of the dual extended kalman filter (DEKF) algorithm. Based on the DEKF algorithm, the SOC under constant current and dynamic discharge conditions are estimated. The results show that the estimation error is within 3%. The influence of battery voltage and current measurement noise on the estimation accuracy of the SOC is then analyzed. It is found that the measurement noise increases the SOC estimation deviation. Finally, the open circuit voltage in measurement equation is replaced by the charging voltage. And a new method of combining DEKF algorithm and charging voltage curve for SOC estimation is proposed. The results of the experiments under constant current and dynamic discharge conditions show that the proposed method can eliminate the measurement noise and ensure the accuracy of SOC estimation. [ABSTRACT FROM AUTHOR]

This study proposes a novel and fast microcalorimetry electrothermal impedance spectroscopy (ETIS) method based on heat generation rate measurements at each electrode of a lithium-ion battery cell. This new method is capable of retrieving the open-circuit voltage, the entropic potential, and the partial entropy changes at each electrode from measurements at a single temperature. It also shortens the measurement duration to a few hours compared to several days using the galvanostatic intermittent titration technique (GITT). The method consists of imposing a sinusoidal current on the cell assembled in an operando isothermal calorimeter. The induced sinusoidal potential response is used to calculate the open-circuit voltage of the cell as a function of the state of charge. The measured heat generation rates are analyzed by fast Fourier transform to determine not only the entropic potential of the cell but also the partial entropy changes at each electrode. This novel microcalorimetry ETIS method was first validated with numerical simulations. Then, it was experimentally demonstrated on battery cells consisting of PNb 9 O 25 or TiNb 2 O 7 working electrodes and metallic lithium counter electrodes in 1 M LiP F 6 in EC:DMC 1:1 v/v electrolyte. The results of the open-circuit voltage and the normalized entropic potential matched those previously determined by potentiometric entropy measurements based on GITT measurements at different temperatures. Furthermore, while the normalized partial entropy changes exhibited notable features at the PNb 9 O 25 or TiNb 2 O 7 working electrodes, they varied little at the metallic lithium counter electrodes. [Display omitted] • Microcalorimetry ETIS was performed in operando isothermal calorimeter. • The procedure was validated by theoretical analysis and numerical simulations. • The method was demonstrated on lab-casted PNb 9 O 25 and TiNb 2 O 7 battery electrodes. • Open-circuit voltage and entropic potential were measured for one cycle within hours. • Partial entropy changes from heat generation rates was retrieved at each electrode. [ABSTRACT FROM AUTHOR]

An ORR/OER bifunctional electrocatalyst, porous nitrogen-doped carbon nanosheet decorated with high valence tungsten doped Co 2 P nanoparticles, has been developed for efficient Zn-air battery through salt template in this work. This catalyst exhibits high ORR (half-wave potential of 0.861 V) and OER activities (overpotential of 310 mV). The results of density functional theory calculation verify that the introduction of high valence tungsten dopants is advantageous to regulate the electronic structure of Co 2 P, thereby has effectively optimized the adsorption energy of intermediate species for ORR/OER and density of states. Meanwhile, the energy barrier of the rate-determining step is greatly lowered. Assembled Zn-air battery (ZAB) exhibits a promising open-circuit voltage of 1.50 V, good power density (224.4 mW cm−2), excellent specific capacity (881 mAh g −1), and durability (130 h). This work elucidated that creating high-performance transition-metal based electrocatalysts for rechargeable Zn-air batteries would be feasible using 5d high valence metal ion doping. [ABSTRACT FROM AUTHOR]

The use of environment-friendly carbonaceous fuels (such as, biomass and synthetic fuels) to produce electricity using solid oxide fuel cells (SOFCs) has emerged as a promising alternative to the use of high-purity hydrogen, which remains as a difficult to produce and store gas. Much effort has been put in the development of SOFC anodes highly active and stable for the use of carbonaceous fuels, such as ceria-based materials, but only recently research has focused on the comprehensive analysis of the interfacial physical-chemical processes affecting their performance. This work presents an in-depth analysis of the interfacial processes occurring at a Mo-doped ceria-yttria stabilized zirconia (YSZ) cermet anode in a SOFC using humidified syngas as fuel. To this end, electrochemical impedance spectroscopy (EIS) data is generated and analysed by the distribution of relaxation times (DRT) method. In addition, gas chromatography analysis of the internal reforming products generated under open circuit voltage (OCV) conditions and post-mortem analysis of the electrode materials after polarization are discussed in support of the DRT results. It is observed that the presence of carbon monoxide (CO) in fuel, as compared to pure hydrogen, influences the anodic charge transfer processes not only due to promotion of the water-gas-shift reaction at the anode two-phase (fuel | electrode) and three-phase (fuel | electrode | electrolyte) interfaces, but also because of its direct electrooxidation at the anode three-phase interfaces. The electrooxidation of carbon monoxide presents a slightly higher activation energy than the electrooxidation of hydrogen (ca. 1.86 and 1.21 eV, respectively), which explains the slower kinetics of SOFCs when using syngas as fuel. Additionally, other oxidation processes of CO at the anode interfaces (such as, the Boudouard reaction) promote the formation of carbon deposits lacking ordered structure, which are more reactive than graphitic structures formed at Ni-YSZ anodes but still can negatively influence the electrochemical kinetics. [ABSTRACT FROM AUTHOR]

• The Fe/NSC-800 catalyst was prepared with a simple and green way. • The introduction of heteroatoms (N, S) through N-rich and S-rich precursor provides more defects and active sites for the electrocatalyst. • Electrocatalyst Fe/NSC-800 has excellent ORR performance and practical application prospects for Zn-air batteries. Currently, the scientific community is keenly interested in the design and production of efficient and durable transition metal electrocatalysts for oxygen reduction reactions (ORR). Therefore, this study reports a simple and reproducible N and S co-doped two-dimensional (2D) hierarchical porous electrocatalyst is reported. NSC the support material first was obtained by pyrolyzing trithiocyanuric acid (TTCA) and loaded on hemin to obtain the final material named Fe/NSC-800. 2D hierarchical porous structures with the large specific surface area were constructed by using TTCA as the template, S source, and additional N source. The addition of hemin not only retained the morphology of the NSC but also provided source of Fe for Fe/NSC-800. The Fe/NSC-800 possessed the limiting current density of 5.85 mA cm–2 and good ORR stability in 0.1 M KOH solution. Based on the excellent ORR performance of Fe/NSC-800, it was assembled into the primary Zn-air battery, which also exhibited satisfactory open circuit voltage (1.55 V) and energy density (880 W h kg–1). This work has contributed to the rational engineering and fabrication of high-performance ORR electrocatalysts for Zn-air battery applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Electrical conductivity of SFM perovskites increased with increasing Fe content. • ODHE resulted in 16.1% C 2 H 6 conversion and 83.1% C 2 H 4 selectivity on SFM45. • Moderate oxygen ionic transport is a key factor for high selectivity to C 2 H 6. • Fast desorption of C 2 H 4 from SFM45 resulted in higher selectivity of C 2 H 4. The oxidative dehydrogenation of ethane (ODHE) was investigated using a solid oxide electrocatalytic cell with Sr 2 Fe 2–X Mo X O 6–δ (SFM) double perovskite as the anode electrocatalyst. As shown in the XRD patterns, SFM perovskites maintained their cubic structure upon modifying the B-site ratios of Mo and Fe. Increasing the Mo content of the perovskite structure resulted in a lower water signal intensity at low temperatures in TPR profiles, indicative of moderate oxygen transport through the perovskite structure. Because Mo–O bonds are stronger than Fe–O bonds, the electrical conductivity of SFM perovskites decreased with increasing Mo content. When operated at 100 mA cm–2, ODHE activity improved four times compared to open circuit voltage, resulting in 16.1% conversion of C 2 H 6 and 83.1% selectivity to C 2 H 4. It has been demonstrated that oxygen ions provided by perovskite lattices were the key species involved in activating C 2 H 6 based on the in-situ DRIFTS experiments. The SFM perovskite with higher Mo content showed the highest conversion and selectivity due moderate oxygen ion mobility and fast desorption of C 2 H 4. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Two types of BiOBr thin films with substantially different crystal stacking and photoelectrochemical (PEC) properties were grown on conducting ITO substrates. In the first case, electrophoretically deposited closely-packed layers with parallel arrangement of (001) faceted plate crystallites (BiOBr||) exhibit p -type PEC behavior in Br 2 /Br− aqueous solution generating cathodic photocurrent under electrochemical polarization. In the second case, BiOBr electrodes composed of plates with predominant perpendicular orientation to the ITO surface (BiOBr⊥) demonstrate opposite PEC behavior and generate anodic photocurrent. This fundamental difference in PEC properties of BiOBr⊥ and BiOBr|| photoelectrodes, which have close values of BET specific surface area (25 and 18 m2/g), plate thickness (15 and 16 nm) and comparable non-equilibrium charge carrier lifetime (in a sub-ns range), is explained by different stacking of plate crystals in them. Since BiOBr has better electronic conductivity within the (001) plane compared to that along the [001] direction, BiOBr⊥ crystallites have better electrical contact with ITO and are subjected to electrochemical polarization, while BiOBr|| crystallites are predominantly in an open circuit condition and their properties are influenced by the boundaries between plate crystals. [ABSTRACT FROM AUTHOR]

Abstract For investigating the influence of coexisting ions (K+, Mg2+, Ca2+ and SO 4 2−), temperature and their synergistic effect on energy generation by reverse electrodialysis, two series of cells dividing with Yadeshi membranes are fed with different solutions at 10 °C, 25 °C and 40 °C. The presence of K+, Mg2+, Ca2+ and SO 4 2− results in lower open circuit voltage, higher internal resistance and lower maximum power density, and the influence order of ions coexisting with NaCl is Ca2+ > Mg2+ (>SO 4 2−) > K+. With the temperature risen, the open circuit voltage and the internal resistance show a trend of increase and decrease respectively, resulting in a bigger power density. Based on the synergistic effect of coexisting ions and temperature, the maximum power density of the pure NaCl system shows a greater increment (0.15 W m−2) than that of NaCl-CaCl 2 (0.10 W m−2) and NaCl-MgCl 2 (0.11 W m−2) systems when temperature increases from 10 °C to 40 °C. Furthermore, the transport quantities of ions in each system increased with temperature at different degrees, and the uphill of Ca2+ and Mg2+ was more obvious, which can reasonably explain the different effects of temperature on the maximum power density. Moreover, these results are further verified when simulated concentrated seawater is used for both the Yadeshi- and Fujifilm membranes, and the Fujifilm shows better energy generation performance mainly due to a lower internal resistance. Graphical abstract The coexisting ions (K+, Mg2+, Ca2+ and SO 4 2−) with NaCl and temperature variation have synergistic effects on energy generation performance of reverse electrodialysis stack. Image Highlights • The presence of K+, Mg2+, Ca2+ and SO 4 2− has a negative impact on power density. • The influence order of coexisting ions with NaCl is Ca2+ > Mg2+ (>SO 4 2−) > K+. • Rising temperature would enhance the power density of reverse electrodialysis. • Temperature affects less on power density in NaCl-CaCl 2 or NaCl-MgCl 2 than NaCl. [ABSTRACT FROM AUTHOR]

We theoretically examine a series of anchors for dye-sensitized solar cells application, with particular attention was paid to the potential of novel pyridinium ylide based anchors. The geometrical structure, electronic property, and optical spectrum of the isolated dyes and its interface with TiO 2 are analyzed by using quantum chemistry calculations. Quantum dynamics simulation is performed to investigate the interface electron transfer process across the dye/TiO 2 interface. The key parameters influencing the short-circuit current and open-circuit voltage are calculated to quantify the performance of different dyes. Our results show that the pyridinium ylide based anchors benefit light-harvesting and improve intramolecular charge transfer character as well as shift up the conduction band edge of TiO 2 semiconductor which further increase short-circuit current and open-circuit voltage. Conjugated rhodanime-3-acetic anchor exhibits the enhanced electron injection than the non-conjugated structure due to the more significant donor-acceptor interaction. The simulation performed in this work demonstrates the potential of novel pyridinium ylide based anchors with respect to the traditional carboxylic acid and rhodanime-3-acetic based anchors, reveals the crucial role of local structure variation in the interface electron transfer, and finally guides the design of high-efficiency sensitizer for dye-sensitized solar cells application. [ABSTRACT FROM AUTHOR]

Zn-based electrodes containing different amount of Bi 2 O 3 have been analyzed by synchrotron XRD during the discharging process of a real Zn/air battery. Bi 2 O 3 is clearly detected for pristine Zn-Bi 2 O 3 based electrodes. However, immersion of Zn-Bi 2 O 3 electrodes in 6 M KOH solution before starting the discharge results in the disappearance of Bi 2 O 3 XRD signature in the pattern and the appearance of new peaks indicating the presence of metallic Bi, regardless of the amount of Bi 2 O 3 initially included in the Zn-Bi 2 O 3 electrodes. This behavior together with Open Circuit Voltage measurements points to a spontaneous reduction of Bi 3+ to metallic Bi by the oxidation of Zn to Zn 2+ . Irrespective of the amount of Bi 2 O 3 present in the negative electrodes, Zn XRD peaks diminish as the discharge proceeds. However, the initial amount of Bi 2 O 3 clearly affect to ZnO and Bi metal XRD peaks. ZnO peaks are observed only for electrodes without Bi 2 O 3 or those containing 6% of Bi 2 O 3 . Conversely, ZnO peaks do not appear in the XRD patterns obtained for higher quantities of Bi 2 O 3 electrodes. Besides, in this case metallic Bi peaks are observed during all discharging processes, indicating that Bi remained in the electrode. Finally, SEM and EDX studies support these conclusions. [ABSTRACT FROM AUTHOR]

In this work, the coaxial electrospinning technique was used to prepare coaxial nanofibers (CNFs) consisting of N-type thermoelectric Nb doped SrTiO 3 (Nb/STO) coated with a thin layer of TiO 2 , which was referred to simply as TiO 2 –Nb/STO. Then a certain amount of TiO 2 –Nb/STO CNFs was added into the TiO 2 nanocrystalline layer to obtain the composite photoanode of dye-sensitized solar cells (DSSCs). Owing to the high electrical conductivity and straightforward electron transport channels for TiO 2 -Nb/STO CNFs, the device assembled with 10 wt% TiO 2 -Nb/STO CNFs demonstrated the highest power conversion efficiency (PCE) of 7.25%, which was significantly higher than the reference one (6.45%). In order to investigate the temperature gradient (ΔT) on the photovoltaic performances of DSSCs assembled with TiO 2 -Nb/STO CNFs, a cold source (0 °C) and a heat source (75 °C) was placed on the Pt counter electrode to create a negative ΔT (−7 K) and a positive ΔT (+7 K), respectively. The mechanism model of thermoelectric effect on the charge transfer dynamic process of DSSCs under different ΔT is established and explained. Data showed that in response to temperature fluctuations, the performance of both reference device and 10% device could be affected. The cold source enable the reference device to obtain the highest PCE of 6.75% due to an increase in open-circuit voltage ( V oc ). This behavior is mainly ascribed to the reduced internal carrier recombination rates, caused by decreased carrier concentrations at low operating temperature. Herein, the operating temperature refers to an average value between the temperatures on both sides of each device. On the contrary, 10% device applying hot source results in an increase of short-circuit current density ( J sc ) and fill factor (FF), yielding the highest PCE of 7.61% despite the negative effects of high operating temperature on V oc . It is found that the hot source benefits the fast electron transfer for 10% device under the synergistic effect of thermoelectromotive force and fast charge carrier diffusion. These results further confirm that the improved photovoltaic performance of 10% device under the condition of hot source was primarily attributed to the thermoelectric Seebeck effect of TiO 2 -Nb/STO CNFs. [ABSTRACT FROM AUTHOR]

Through-plane in operando neutron radiography was used to differentiate between anode feed water and cathode water (transported through the membrane) to resolve oxygen gas bubbles in the anode. In this work, we investigated the impact of cathode purging on the electrochemical performance of polymer electrolyte membrane (PEM) electrolyzers as well as its impact on neutron radiographic imaging to inform our recommendations on how to prescribe an optimal cathode purging rate. We found that excessive dry nitrogen purging in the cathode led to an increase in ohmic resistance and a decrease in the open circuit voltage. Therefore, an optimal nitrogen purging rate must be prescribed during visualization studies to maximize the precision of oxygen gas quantification without unintentionally altering the electrochemical performance. We demonstrated that the optimal cathode nitrogen purge rate can be determined by monitoring the spatial distribution of the anode oxygen gas and that this optimal purge rate is a function of the operating current density. [ABSTRACT FROM AUTHOR]

A parameter study of 20 solid oxide electrolysis cells was carried out to systematically investigate long-term degradation each over 1000 h under variation of temperature, humidity and current density. The influence of operating temperature was investigated between 750 and 850 °C, the humidity ranged from 40% to 80% H 2 O, and the current density varied between open circuit voltage (OCV) and 1.5 A cm −2 . The progress of degradation was monitored in-situ by electrochemical impedance spectroscopy. Five different contributions to the spectra were identified by calculating the distribution of relaxation times and separated via a complex non-linear square fitting routine. The present work focuses on the degradation of the fuel electrode. From SEM analysis, Ni depletion and an increased pore fraction close to the electrode/electrolyte interface was derived, which is correlated with an increased ohmic resistance of the cells. This unidirectional transport of Ni away from the fuel electrode/electrolyte interface leads to an effective electrolyte extension and is the main source of degradation. Ni depletion is shown to be driven by current density and its extent is shown to be dependent on the complex interplay between the operating parameters current density, anode overpotential, humidity and temperature. It is particularly pronounced for p H 2 O larger than 0.8 atm and temperatures above 800 °C. Furthermore, the fuel electrode electrochemistry also exhibits degradation in the high-frequency region around 10 4  Hz. [ABSTRACT FROM AUTHOR]

We found that the electrical state in which dye solar cells operate affect their ageing. Three states were analysed: open-circuit (OC), short circuit (SC), and under maximum power point (MPP) / load. OC and SC are more or less atypical states, which are relevant while storing cells or in the event of malfunction, whereas the MPP/load corresponds to real life operation of the cells. Our results indicate that keeping the cells at OC or near the MPP lead to practically identical stability, whilst the cells at SC degraded much faster in a 1000 h light soaking test. The underlying cause for the degradation of all the cells was the loss of tri-iodide (i.e. limiting charge carriers) in the electrolyte. While the degradation mechanism appears to be the same, the loss rate of tri-iodide was about five times faster with SC than with OC and MPP cells. In the SC cells, the loss of tri-iodide decreased both the short-circuit current and fill factor resulting in a 36% efficiency loss by the end of the test. In contrast, the efficiency of the OC and load cells remained quite stable throughout the test. Since OC is the most commonly used state in aging tests, it is good news for ageing studies that the real life MPP state and the OC state yield roughly similar results. The identification of the degradation pathway, the loss of charge carriers, and the related degradation rate were used to estimate the remaining lifetime of cells which did not degrade during the 1000 h test. Based on the degradation rate related to the charge carrier loss, full degradation of the OC and MPP cells is expected in approximately 3000 h of operational time. [ABSTRACT FROM AUTHOR]

Traditional electrochemical algorithms are too complex for use in real-time battery management systems (BMSs). Determination of parameters and implementation of algorithms are the key challenges for electrochemical models for Li-ion batteries. This paper develops a simplified electrochemical model that incorporates open-circuit voltage, liquid-phase diffusion, reaction polarization, and ohmic polarization, and uses a fast operating test to identify all the parameters to solve these challenges. The model is then implemented and compared against experimental measurements. Validations of parameter estimation and charge/discharge behaviors indicate that the developed parameter estimation method for the electrochemical model is effective. With this model and parameter estimation technique, electrochemical model-based state of charge (SOC) estimation can be realized online and can provide accurate results. [ABSTRACT FROM AUTHOR]

Five new metal free organic dyes festooned with fluorene and fused thiazine structural units such as FPAA1, FPAA2 and FPTAA1–FPTAA3 have been synthesized by adopting multistep synthetic strategy and investigated nanocrystalline TiO 2 based dye-sensitized solar cell performance by utilizing the same as sensitizers. Further, electrochemical, photophysical, and computational studies have been explored. Computational studies have been carried out to determine the electronic distribution within the molecules. Of the devices fabricated, the ones incorporated with cyanoacrylic acid acceptor exhibit greater power conversion efficiencies along with superior electron life time, short-circuit current and open-circuit voltage than the others integrated with (4-oxo-2-thioxothiazolidin-3-yl)acetic acid acceptor. Among them, the dye FPAA1 possessing device exhibited highest PCE of 7.54% besides open circuit voltage ( V OC ) of 751 mV, short circuit current density ( J SC ) of 15.65 mA cm −2 , and fill factor ( ff ) of 0.60. [ABSTRACT FROM AUTHOR]

A more accurate and reliable method is proposed to evaluate the photoelectrochemical (PEC) performance of semiconductor toward water splitting. Conventionally, I-t measurements are conducted at a fixed potential relative to the reference electrode, e.g., 0 V vs. Ag/AgCl, to monitor the photocurrent, which has been regarded as a direct indicator for performance comparison among different electrodes. Considering that the open-circuit potential (OCP) varies from electrode to electrode, the photocurrent comparison at a fixed potential may misrepresent the actual differences between samples. Here, we study the PEC performance by applying two distinct external bias values, one at 0 V vs. Ag/AgCl deriving from the conventional practice and the other at 0.1 V vs. OCP representing the exactly fixed applied overpotential. Two experimental groups are designed to address the arguments, including the influence of heat treatment for ZnO nanorod arrays and the global comparison among ZnO, TiO 2 , Au particle-decorated TiO 2 , and CdS electrodes. Different trends in photocurrent are observed at the two distinct biases, with the results from 0.1 V vs. OCP conforming to the general considerations. The results suggest that application of a fixed potential relative to the OCP will provide a more fair comparison for accurate PEC performance evaluation without under- or over-estimation. [ABSTRACT FROM AUTHOR]

Equivalent circuit model (ECM)-based state-of-charge (SOC) estimation has been considered as one of the most important aspects in battery management system (BMS). However, in case of a lithium iron phosphate (LiFePO 4 ) cell, because of the flatness and hysteresis effect of the open-circuit voltage (OCV) curve, there are inevitable drawbacks directly related to both erroneous SOC information and the slow SOC convergence speed caused by incorrect OCV characteristics. Therefore, this approach gives insight to the design and implementation of the ECM-based SOC estimator that is suitable for an actual LiFePO 4 cell. Two approaches for settlement in current OCV issues are as follows. Firstly, through linearization between coordinated charging and discharging OCVs, an OCV hysteresis model can be easily implemented. This model incorporating OCV measurement data is adequately applied to the model-based SOC estimator using the extended Kalman filter (EKF). Secondly, a well-adjusted measurement error covariance controlled in the EKF is used to alleviate an undesired SOC fluctuation that surely results in low BMS performance. This measurement error covariance additionally enables us to provide the fast SOC convergence speed against an inaccurate initial SOC value. This approach has been sufficiently validated by extensive experimental results conducted on LiFePO 4 cells that had a rated capacity of 14 Ah by EIG. Consequently, our validation showed the clearness of the proposed work for a reliable SOC estimator of a LiFePO 4 cell. [ABSTRACT FROM AUTHOR]

A proton conducting anode NiO-BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) is investigated to play a dual role in avoiding internal shorting and carbon deposition of ceria-based SOFCs by experimental and numerical methods. The electronic barrier layer Ba x Ce 1−y Sm y O 3-δ (BCS) can be in-situ formed at the interface of anode and electrolyte, which improves the open-circuit voltage (OCV) and the peak power density. To deeply analyze the electron-blocking effect and optimize the thickness ratio of the BCS layer, electronic conductivities, leakage current densities and cell efficiencies considering the internal shorting and polarization are calculated by a mathematic model. Importantly, this ceria-based cell with the proton conducing anode also shows superior electrochemical performance and stability using wet methane as fuel. A thermodynamic equilibria calculation considering the water adsorption capacity of the anode is performed to predict the equilibrium composition and carbon deposition boundaries, which quantitatively explains the excellent carbon-tolerance of the cell. The superior bifunctional proton conducting anode enables ceria-based electrolytes to be promising electrolyte candidates toward the application of low temperature SOFCs and provides an efficient path for avoiding carbon deposition. [ABSTRACT FROM AUTHOR]

The influence of surface crystallography and applied potential on the thiol-exchange procedure to create mixed alkylthiol DNA SAMs is detailed. A single crystal gold bead and fluorophore labeled thiol modified DNA were used to characterize the resulting surface modifications. The thiol-exchange occurs with different efficiencies on the low index planes (111,100,110) as compared to 311 and 210. Positive applied potentials (>0/SCE) result in 10 × higher coverage than when compared to deposition at the open circuit potential (OCP) over the same 60 min time period. Negative potentials ( < 0/SCE) resulted in less uniform coverage with the 111 facet being significantly modified. The electrolyte used during the deposition was a 10 mM TRIS Buffer with 100 mM NaCl 500 mM MgCl 2 . The influence of [ Cl − ] was studied showing it had a significant impact on the thiol-exchange at the positive potentials, where higher [ Cl − ] resulted in higher DNA coverages and a more uniform coverage across the multi-crystalline surface. The local environment of the thiol-exchanged DNA SAMs were compared for different regions on the surface using potential driven DNA reorientation modulating the fluorescence intensity. These results showed a common behaviour from all surfaces suggesting that the DNA SAMs prepared by thiol-exchange were consistently prepared with a variable surface concentration controlled by potential and time. [ABSTRACT FROM AUTHOR]

Alkaline doping (Cs, Rb) in CH 3 NH 3 PbI 3 (MAPbI 3 ) is known to enhance the stability of perovskite solar cells. The films are usually deposited using anti-solvent method, which is tricky and not applicable for large scale deposition. Besides, in case of Cs x MA 1−x PbI 3 the amount of Cs must be carefully controlled to prevent CsI phase formation. Herein, we report an atmospheric pressure vapor assisted solution process (AP-VASP) for the growth of Cs doped MAPbI 3 perovskite films that features highly uniform morphology, pin-hole free films, large grain size, as well as being scalable. The Cs x MA 1−x PbI 3 films are formed by the reaction of Cs doped PbI 2 films with MAI vapor in a simple oven. We demonstrate a simple method for obtaining Cs x MA 1−x PbI 3 films with Cs content as high as 20% without phase segregation of CsPbI 3 or CsI. Impedance spectra measurements reveal that Cs incorporation into MAPbI 3 increases recombination resistance, up to 83% (28 vs. 15 Ω cm 2 ), resulting in higher open circuit voltage and efficiency. The photovoltaic performance is considerably improved by Cs doping, with the highest efficiency being 14.1% for the Cs 0.1 MA 0.9 PbI 3 cells compared with 13% for the MAPbI 3 ones. As expected, Cs 0.1 MA 0.9 PbI 3 cells show better stability compared to MAPbI 3 cells. [ABSTRACT FROM AUTHOR]

• LIG was demonstrated as a counter electrode for DSSC with Cu-based electrolyte. • LIG-based DSSC and LIG-based EDLC were integrated in a self-powered storage system. • LIG outperformed PEDOT as flexible counter electrode in DSSC with Cu-based electrolyte. Dye-sensitized solar cells (DSSCs) are gaining a newfound interest thanks to their superior ability to harvest indoor light with efficiency higher than other photovoltaic technologies. This study reports, for the first time, the possibility of using laser-induced graphene (LIG) as a flexible counter electrode material for DSSCs. A flexible LIG (F-LIG) electrode was fabricated by direct laser writing of a polyimide film, without the need of a starting conductive substrate. The prepared electrodes showed a higher catalytic activity towards the reduction of I 3 −/I−with respect to a more expensive Pt-based counter electrode. Moreover, the F-LIG electrodes outperformed electrodeposited PEDOT as a catalytic material for reduction of a copper bipyridyl complex (Cu(II/I)(tmby) 2 TFSI 2/1) electrolyte. The F-LIG based DSSCs showed an open circuit voltage as high as 0.94 V and an increase in photoconversion efficiency higher than 60% with respect to the PEDOT-based counterpart, stepping from 3.08% to 4.96%. Thanks to the easy one-step laser-based fabrication process, the LIG-based DSSC was integrated with a LIG-based supercapacitor (SC), obtaining a flexible energy harvesting and storage system that was able to self-charge both under simulated solar illumination and under indoor artificial illumination, appearing to be a promising energy source for the next generation of self-powered connected Internet of Things devices. [Display omitted] [ABSTRACT FROM AUTHOR]

• A model for SOH estimation and degradation diagnosis is present. • Proposing a method to select appropriate segments of charging data as model input. • This model development process does not rely on aging data. • The method is validated on real aging data. Lithium-ion batteries (LiBs) have been widely used in electric vehicles and portable electronics. However, the performance and safety of these applications are highly dependent on degradation of LiBs. In this paper, three contributions have been made to achieve reliable degradation diagnosis and State-of-Health (SOH) estimation: (1) Open-circuit voltage is reconstructed to diagnose degradation modes of LiBs by performing scaling and translation transformations on open-circuit potential curves. (2) A degradation diagnosis model is developed to quantify aging characteristics of LiBs. In this model, a segment of charging data is taken to estimate SOH and the degradation modes in a degradation path. (3) An appropriate voltage range of the charging data is selected to improve model estimation accuracy. Experimental results show that the proposed method can achieve reliable degradation diagnosis and accurate SOH estimation with the maximum error of 1.44%. [Display omitted] [ABSTRACT FROM AUTHOR]

• The hierarchically Pt-HPCF material with ultralow Pt loading was synthesized. • Pt-HPCF catalyst exhibits efficient catalytic activity and stability towards ORR. • High catalytic performance is benefited from the multi-level synergistic optimization. • Pt-HPCF catalyst displays promising perspective in ZAB. Improving the utilization efficiency of platinum (Pt) is required for realizing the efficient oxygen reduction reaction (ORR) in rechargeable Zn–air battery (ZAB). Herein, a carbon fiber decorated with coexistence of uniformly dispersed Pt nanoparticles and Pt-N-C moieties (Pt-HPCF) is synthesized and used as electrocatalyst for ORR. The elaborately structural design of Pt-HPCF catalyst on atomic/nanoscopic, mesoscopic and macroscopic level guarantees highly accessible activity sites, fast reactants transport, rapid electron transfer, and strong metal-support interaction. Benefited from the multi-level synergistic optimization, this unique Pt-HPCF electrocatalyst with ultralow Pt loading presents excellent ORR activity with a mass activity of 912.08 mA mg−1 at 0.85 V, which is 7.5 times that of the corresponding value for commercial Pt/C catalyst. Moreover, Pt-HPCF also exhibits high stability after accelerated degradation test. Furthermore, ZAB assembled with Pt-HPCF catalyst exhibits a high open circuit voltage (OCV) of 1.576 V, high capacity of 840 mAh g−1 at 5.0 mA cm−2, and a large peak power density of 163.38 mW cm–2. This work provides a feasible route for optimizing the Pt or other metal-based electrode in energy storage/conversion fields. [Display omitted] [ABSTRACT FROM AUTHOR]

The end-of-life (EOL) of a lithium ion battery (LIB) is defined as the time point when the LIB can no longer provide sufficient power or energy to accomplish its intended function. Generally, the EOL occurs abruptly when the degradation of a LIB reaches the threshold. Therefore, current prediction methods of EOL by extrapolating the early degradation behavior often result in significant errors. To address this problem, this paper analyzes the reason for the EOL threshold of a LIB with shallow depth of discharge. It is found that the sudden appearance of EOL threshold results from the drift of open circuit voltage (OCV) at the end of both shallow depth and full discharges. Further, a new EOL threshold prediction model with highly improved accuracy is developed based on the OCV drifts and their evolution mechanism, which can effectively avoid the misjudgment of EOL threshold. The accuracy of this EOL threshold prediction model is verified by comparing with experimental results. The EOL threshold prediction model can be applied to other battery chemistry systems and its possible application in electric vehicles is finally discussed. [ABSTRACT FROM AUTHOR]

A novel semiconductor-ionic La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF)-Sm/Ca co-doped CeO 2 (SCDC) nanocomposite has been developed as a membrane, which is sandwiched between two layers of Ni 0.8 Co 0.15 Al 0.05 Li-oxide (NCAL) to construct semiconductor-ion membrane fuel cell (SIMFC). Such a device presented an open circuit voltage (OCV) above 1.0 V and maximum power density of 814 mW cm −2 at 550 °C, which is much higher than 0.84 V and 300 mW cm −2 for the fuel cell using the SCDC membrane. Moreover, the SIMFC has a relatively promising long-term stability, the voltage can maintain at 0.966 V for 60 hours without degradation during the fuel cells operation and the open-circuit voltage (OCV) can return to 1.06 V after long-term fuel cell operation. The introduction of LSCF electronic conductor into the membrane did not cause any short circuit but brought significant enhancement of fuel cell performances. The Schottky junction is proposed to prevent the internal electrons passing thus avoiding the device short circuiting problem. [ABSTRACT FROM AUTHOR]

A numerical model for ceria-based solid oxide fuel cells (SOFCs) with bi-layer electrolyte is proposed to evaluate the internal short circuit by the comparison of two cell configurations: the electronic barrier electrolyte adjacent to cathode and anode, respectively. In this model, the activation polarization of the electrode reaction and the charge transport of the electrolyte with both n/p-type electronic and oxygen ion conductivity are considered. The activation polarization and the charge transport are described by the Butler-Volmer equation and the Nernst-Planck equation, respectively. Parametric simulations are performed to compare the two bi-layer electrolyte configurations in terms of the open circuit voltage, I–V relationship, leakage current density, power density at 0.7 V, oxygen partial pressure distribution and electrochemical efficiency as functions of the temperature and thickness ratio of the electronic barrier electrolyte. From our modeling results, the cell configuration of which the barrier electrolyte is adjacent to cathode has significant p-type leakage current, leading to the lower open circuit voltages and electrochemical efficiency than the other one. The oxygen partial pressure distribution under the open circuit displays the “S” type in the barrier layer, which is related to the change of the n/p-type conductivity of the barrier layer. Besides, the activation polarization greatly influences the open circuit voltage and the oxygen partial pressure distribution between boundaries of electrolytes under open circuit. It is also found that the thickness ratio of the electronic barrier electrolyte can be optimized to maximize the electrochemical performance by balancing the open circuit voltage and ohmic polarization loss. [ABSTRACT FROM AUTHOR]

Dye sensitized solar cells (DSSCs) have received significant attention due to their low production cost and easy fabrication process. However, the leakage and volatilization of the liquid organic solvent in the liquid electrolyte affect the long term stability of DSSCs. Therefore, in this present work, to improve the durability of DSSCs, polymethyl methaacrylate (PMMA) based polymer gel electrolyte (PGE) with different weight percent of carbon black (CB) was studied to replace the conventional liquid electrolyte. CB was used to improve the ionic conductivity of the PGE. DSSCs fabricated with the prepared PGEs exhibit very good long term stability in comparison to liquid electrolyte. The optimized DSSC with 0.57 weight percentage of CB in PMMA polymer matrix exhibits the highest photo-conversion efficiency of 5.52 ± 0.03% with short circuit current density (J sc ) value of 12.43 ± 0.04 mA cm −2 , open circuit voltage (V oc ) value of 766.02 ± 0.52 mV and fill factor (FF) value of 58.01 ± 0.02%. A significant enhancement of V oc is observed with the employment of the PGE. The impact of the PGE in the enhancement of V oc was studied by analyzing the charge transfer kinetics data at the interface of the photoanode and the PGE. Furthermore, the study of long term stability shows that after 1000 h of testing the optimized DSSC (PGE(0.57)) retains the J sc value at 83% of the initial performance exhibiting very significant long term stability in comparison to the DSSC fabricated with liquid electrolyte. [ABSTRACT FROM AUTHOR]

The contributions of the ionic transport through a cation-exchange membrane, with perfectly stirred bathing solutions, on the open circuit voltage and the membrane ohmic resistance under reverse electrodialysis conditions, have been theoretically investigated. The Nernst-Planck flux equations, together with the Donnan equilibrium relations and the electrical neutrality condition, are numerically solved by using the network simulation method. On the one hand, the voltage-current characteristic, the polarization curves and the contributions of the ion-exchange membrane to the open circuit voltage and the membrane resistance are studied in a single system with NaCl solutions. The results are compared to those analytically obtained by using linear variations of ionic concentrations inside the membrane. On the other hand, a similar study is done for a membrane immersed in solutions constituted by a mixture of NaCl and MgCl 2 . The uphill transport of the divalent cation against its concentration gradient is considered in the interpretation of the results. The numerical results are compared to those analytically obtained by considering the hypothesis of total co-ion exclusion inside the membrane. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cell (PEMFC) catalysts manufactured using atomic layer deposition (ALD) on unmodified and functionalized carbon were compared to a commercial catalyst in half- and whole-cell tests. Half-cell tests showed the ALD catalyst performed better or comparable to a commercial catalyst. Conversely, whole-cell tests revealed flooding in the ALD catalyst produced on functionalized carbon. Residual functional groups had reduced the hydrophobicity, and rendered this catalyst impractical for use in whole-cell PEMFC applications. However, the ALD catalyst produced on unmodified carbon performed better than the commercial catalyst, which illustrates the power of ALD on appropriate catalyst supports. [ABSTRACT FROM AUTHOR]

Electrochemical measurements on solid oxide fuel cells (SOFC) often uncover unusual readings. These are then ascribed to unknown material properties or newly discovered physical effects. However, a closer look shows that these are simply errors − mostly test artefacts. Our group has isolated many causes of error and developed reliable techniques to avoid them, focusing on open circuit voltage (OCV) measurement, current/voltage (i/v) curves and electrochemical impedance spectroscopy (EIS). This paper aims to help researchers avoid errors through balanced choice of apparatus and test procedure. Simple to implement test-sequences are set out to avoid errors. First, test-bench wiring, hardware limitations and apparatus selection are detailed to avoid error sources. Secondly, measurement settings and how they impact measurement results are discussed. Our developed procedures avoid the majority of errors; this is exhaustively tested at operationally relevant conditions. [ABSTRACT FROM AUTHOR]