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Lithium ion conducting membrane has been prepared based on cellulose acetate and LiCl using the solution casting method. Amorphous/crystalline nature of the prepared membranes are analyzed using X-ray diffraction. The surface of the prepared membrane is analyzed using SEM. Complexation of cellulose acetate and LiCl is confirmed using Fourier transform infrared spectroscopy. The ionic conductivity of the examined membranes is determined through AC impedance measurement. The membrane, comprising 1 g cellulose acetate with 0.8 weight% (wt%) of LiCl, exhibits the highest Li-ion conductivity of 7.1 × 10−3 S cm−1 among all prepared membranes. Thermal stability of the prepared membranes is analyzed using Differential scanning calorimetry and Thermogravimetric analysis. The electrochemical stability of the highest Li-ion conducting membrane has been analyzed using Linear sweep voltammetry (LSV), and the potential window was found to be 1.76 V. Using the highest Li-ion conducting membrane, the primary Li-ion conducting battery and coin cell is constructed. Primary Li-ion conducting battery shows an Open-circuit voltage (OCV) of 1.8 V and its performance has been studied using various loads. The stability of the coin cell is analyzed using the Galvanostatic charge-discharge. The performance of the highest Li-ion conducting membrane as an electrolyte in an electrochemical storage device is analyzed in the present work. [ABSTRACT FROM AUTHOR]

A clean energy requirements for bio-power emphasize the need for technological improvements in the solid polymer electrolyte (SPE) domain. This exceptionally high-skill field has assumed a crucial role in planning energy-based equipment in recent years, which has replaced fluid electrolytes in electrochemical sensors, fuel cells, and electrochemical devices. Materials based on lithium conduction, which is used to develop electrochemical devices play a major role for the same. Eco-friendly materials have gained a fair amount of importance for facing an energy crisis, the warming of the earth and the very concept of the resilient energy revolution. Extensive study is going on to develop biopolymer-based electrochemical devices, rather than conventional artificial polymers owing to their high cost and ecologically unfriendly nature. Cellulose Acetate having different concentrations of Lithium Chloride (LiCl) has been prepared by the solution casting technique and characterized by XRD. The highest conductivity of 2.136 x 10-2 Scm-1 observed amongst the various samples was achieved by the concentration of 10:90 percent of CA : LiCl. The high amorphicity is based on the results of the powder XRD process. A Lithium ion-based battery has been developed by utilizing the biopolymer electrolyte membrane having the highest conductivity, and its open load voltage, and nominal voltage are estimated. [ABSTRACT FROM AUTHOR]

Small coin cell batteries are predominantly used for testing lithium‐ion batteries (LIBs) in academia because they require small amounts of material and are easy to assemble. However, insufficient attention is given to difference in cell performance that arises from the differences in format between coin cells used by academic researchers and pouch or cylindrical cells which are used in industry. In this article, we compare coin cells and pouch cells of different size with exactly the same electrode materials, electrolyte, and electrochemical conditions. We show the battery impedance changes substantially depending on the cell format using techniques including Electrochemical Impedance Spectroscopy (EIS) and Galvanostatic Intermittent Titration Technique (GITT). Using full cell NCA‐graphite LIBs, we demonstrate that this difference in impedance has important knock‐on effects on the battery rate performance due to ohmic polarization and the battery life time due to Li metal plating on the anode. We hope this work will help researchers getting a better idea of how small coin cell formats impact the cell performance and help predicting improvements that can be achieved by implementing larger cell formats. [ABSTRACT FROM AUTHOR]

The solid electrolyte interface (SEI) layer is a surface film formed by the decomposition of the electrolyte in a lithium-ion battery on the anode surface. A proper understanding of the SEI layer formation process in graphite anodes can provide a broader view of overcoming the challenges associated with these anodes, which will lead to better charge/discharge performance. In this research, cyclic voltammetry tests, electrochemical impedance spectroscopy and sequential charge/discharge tests have been used for cell to gain an accurate understanding of the SEI film formation process on the graphite anode surface. The results of the cyclic voltammetry test show that most of the SEI layer is formed in the first cycle and reaches stability with the continuation of the voltammetric cycles of the SEI layer. Also, the charge transfers resistance (Rct) has decreased from 123.5 Ω to 27.96 Ω after the electrochemical cycles, which indicates the facilitation of the charge transfer process after the formation of the SEI layer. The results of the consecutive charge/discharge test of anode graphite coin cell also show that the amount of non-reversible capacity in the first cycle is much higher than the amount of non-reversible capacity in subsequent cycles. This indicates the formation of a large part of the SEI layer in the first cycle. Considering that the SEI layer is almost stable after the second cycle, it can be said that the method of forming a lithium-ion cell with graphite anode can be done in two charge/discharge cycles.

ABSTRACT: Owing to the difficulty of studying materials in real-life battery context, research on metal anodes, suffers from a methodological gap between materials- and device-orientated studies. This gap can be bridged by quantitatively linking the electrical response of the device to the evolution of the material inside the cell. The capability of establishing this link, on the one hand, allows to frame the correct space- and time-scales that are relevant to device research and, on the other hand, helps pinpoint the global observables that can be associated with molecular-level information and imaging. This study contributes to the construction of a conceptual platform, that will enable to rationalize the electrical response of the device on the basis of materials-relevant quantities. To this aim: (i) we have developed a PDE-based mathematical model for the response of a single symmetric cell with metal electrodes; (ii) we have validated it with high-quality data from Zn/Zn symmetric coin-cell cycling in weakly acidic alkaline aqueous electrolyte, containing quaternary ammonium additives, and (iii) we have carried out a parameter-classification task for the experimental data, that notably extended the physico-chemical insight into the mechanism of action of anode-stabilizing additives.

Due to the simple structure and the possibility of manual production, coin cells enable fast and, compared to larger cell formats, an inexpensive examination option in battery research. The comparability and traceability of coin cell structures in literature are only feasible to a limited extent due to the lack of a standard in manual production. Since the findings from the literature are barely building up on each other and have not been repeated, a full factorial Design of Experiments (DoE) was performed to investigate the significance of earlier findings in terms of their influence on the reproducibility of the performance. The parameters studied were the anode-to-cathode ratio, the amount of electrolyte, the spring type and the separator count. To quantify the reproducibility of coin cell assembly, the number of functional cells (here: successful formation followed by 30 cycles) and the empirical coefficient of variation for the performance parameters discharge capacity, internal resistance and coulombic efficiency were compared. The critical parameters found in prior literature have no statistically significant influence on reproducibility when focusing on the number of functional cells. Instead, other uninvestigated parameters seem to influence the system coin cell more. By further examining the parameter settings that produced the most functional cells (≥75% of 8 cells), guidance for constructing coin cells (type R2032) was suggested, and other potential influencing parameters are discussed for further study. [ABSTRACT FROM AUTHOR]

For the research and development of new battery materials, achieving high reproducibility of the performance parameters in the laboratory test cells is of great importance. Therefore, in the present work, three typical small-format lithium-ion cells (coin cell, Swagelok cell and EL-CELL ECC-PAT-Core) were tested and compared with regard to the reproducibility of their performance parameters (discharge capacity, internal resistance and coulombic efficiency). A design of experiments (DOE) with the two factors separator type and anode–cathode ratio (N/P ratio) was carried out for all cells. For the quality features discharge capacity, internal resistance and coulombic efficiency, the coefficient of variation is used as a measure of reproducibility. The statistical evaluation shows that in 83% of all cases, higher reproducibility is achieved when the Freudenberg separator is used instead of the Celgard separator. In addition, higher reproducibility is achieved in 78% of all cases if the anode and cathode are the same size. A general statement about which test cell format has the highest reproducibility cannot be made. Rather, the format selection should be adapted to the requirements. The examined factors seem to have an influence on the reproducibility but are more insignificant than other still-unknown factors. Since the production of small-format test cells is a manual process, the competence of the assembler seems to prevail. In order to mitigate the influence of as many unknown variables as possible, assembly instructions are proposed for each cell type. [ABSTRACT FROM AUTHOR]

• Sulfur/few-layer graphene (S/FLG) composite, as a cathode material with high sulfur. • Defects and edges found in FLG-OH as polysulfide reservoirs for shuttle effect. • S/FLG-OH shows a high specific capacitance of 157.4 F g−1. • When applied as a cathode host on a coin cell it obtained a voltage of about 2.6 V. • Cell with S/FLG-OH as the cathode shows a stable potential over 50 cycles. Over the past years, significant advantages have been introduced to upgrade the performance of lithium-sulfur battery (Li-S) batteries since their prototype in the 1960s. Due to high theoretical energy density and cost efficiency, Li-S batteries have obtained great attention and have made great progress in the last few years. In this work, we developed the sulfur-attached few-layer graphene composite (S/FLG), sulfur-attached functionalized few-layer graphene using acetic acid (S/FLG-COOH) and sulfur-attached functionalized few-layer graphene using strong acid H 2 SO 4 and HNO 3 (S/FLG-OH) as a cathode material with high sulfur loading. The material's structure is confirmed through XRD. The surface morphology is confirmed through SEM and elemental composition has been obtained through EDAX. The functional groups are confirmed through FTIR. The defect level and number of layers are confirmed through Raman characterization with an excitation laser wavelength of 532 nm. The electrochemical performance of three cathodes is also identified through EIS, CV, and GCD characterization. Meanwhile, highly developed defects and edges found in the functionalization of few-layer graphene using the strong acid (H 2 SO 4 and HNO 3) which consists of a hydroxyl functional group (FLG-OH) serve as polysulfide reservoirs to mitigate the shuttle effect. Among these cathodes, S/FLG-OH shows a high specific capacitance of 157.4 F g−1 and when applied as a cathode host on a coin cell it obtained a voltage of about 2.6 V. Well-performed S/FLG-OH cathode was used to fabricate the Coin Cell. The fabricated Coin Cell with S/FLG-OH as the cathode shows a stable potential over 50 cycles. [ABSTRACT FROM AUTHOR]

Due to the simple structure and the possibility of manual production, coin cells enable fast and, compared to larger cell formats, an inexpensive examination option in battery research. The comparability and traceability of coin cell structures in literature are only feasible to a limited extent due to the lack of a standard in manual production. Since the findings from the literature are barely building up on each other and have not been repeated, a full factorial Design of Experiments (DoE) was performed to investigate the significance of earlier findings in terms of their influence on the reproducibility of the performance. The parameters studied were the anode-to-cathode ratio, the amount of electrolyte, the spring type and the separator count. To quantify the reproducibility of coin cell assembly, the number of functional cells (here: successful formation followed by 30 cycles) and the empirical coefficient of variation for the performance parameters discharge capacity, internal resistance and coulombic efficiency were compared. The critical parameters found in prior literature have no statistically significant influence on reproducibility when focusing on the number of functional cells. Instead, other uninvestigated parameters seem to influence the system coin cell more. By further examining the parameter settings that produced the most functional cells (≥75% of 8 cells), guidance for constructing coin cells (type R2032) was suggested, and other potential influencing parameters are discussed for further study.

For the research and development of new battery materials, achieving high reproducibility of the performance parameters in the laboratory test cells is of great importance. Therefore, in the present work, three typical small-format lithium-ion cells (coin cell, Swagelok cell and EL-CELL ECC-PAT-Core) were tested and compared with regard to the reproducibility of their performance parameters (discharge capacity, internal resistance and coulombic efficiency). A design of experiments (DOE) with the two factors separator type and anode–cathode ratio (N/P ratio) was carried out for all cells. For the quality features discharge capacity, internal resistance and coulombic efficiency, the coefficient of variation is used as a measure of reproducibility. The statistical evaluation shows that in 83% of all cases, higher reproducibility is achieved when the Freudenberg separator is used instead of the Celgard separator. In addition, higher reproducibility is achieved in 78% of all cases if the anode and cathode are the same size. A general statement about which test cell format has the highest reproducibility cannot be made. Rather, the format selection should be adapted to the requirements. The examined factors seem to have an influence on the reproducibility but are more insignificant than other still-unknown factors. Since the production of small-format test cells is a manual process, the competence of the assembler seems to prevail. In order to mitigate the influence of as many unknown variables as possible, assembly instructions are proposed for each cell type.

Non-metal-based compounds have emerged as promising electrodes in recent years to replace scarce and expensive transition-metals for energy storage applications. Herein, a simple electro-spinning technique followed by carbonization is used to create tetraphosphorus triselenide (P 4 Se 3) nano-flakes encapsulated in carbon nanofiber (P 4 Se 3 @CNF) to obtain a binder-free, metal-free and flexible hybrid electrode with high electrical conductivity and cyclic stability. A remarkable capacitive performance (5.5-folds@P 4 Se 3) of 810 F g-1/112.5 mAhg−1@0.9 A g-1 has been obtained using P 4 Se 3 @CNF electrode with an excellent rate capability compared to pristine (P 4 Se 3) which is further supported by theoretical calculations via intercalating graphene within bare P 4 Se 3 flakes inducing partial charge redistribution in hetero-structure. A flexible pouch-type hybrid-supercapacitor followed by coin-cell has been manufactured offering exceptional energy density without sacrificing power density and ultra-long durability over 35,000 and 1,00,000-cycles with capacitance-retention of 99.77 % and 100 %, respectively. It has been demonstrated that as-fabricated device has practical usefulness towards renewable energy harvesting and storage via integrating commercial solar cell module with supercapattery array that can enlighten the blue LED approximately for 31 min, rotate the homemade windmill device, power Arduino and glow "INST" against 2 min of charging. This work demonstrates a facile route towards the development of metal-free electrochemical renewable energy storage/transfer devices offering an inevitable adoption in industrial platforms. Efficient renewable energy harvesting and storage are achieved through the integration of a commercial solar cell module with a non-metal-based supercapattery array (two coin cells in series). This configuration powers a red LED for an impressive 30 min after just 2 min of charging. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Green synthesis of α-V 2 O 5 nanosheets using Aloe Vera leaf extract. • Electrochemical phase transformation of α-V 2 O 5 to NaV 3 O 8 nanosheets. • Structural and morphological evolutions during electrochemical phase transformation. • Specific capacitance of 640.10 F g−1 at 0.5 A g−1 NaV 3 O 8 nanosheets electrode. Nowadays, cost-effective and environmentally friendly supercapacitors (SCs) with high energy and power densities are gaining significant research attention since they could broaden the application of capacitors. The present study demonstrates a low-cost green synthesis technique to prepare the α-V 2 O 5 phase using Aloe Vera leaf extract. X-ray diffraction technique confirmed the formation of the orthorhombic α-V 2 O 5 phase. The prepared α-V 2 O 5 was employed as an electrode material for SC application. During an electrochemical cyclic voltammetry test in Na 2 SO 4 electrolyte, Na+ ions intercalation and de-intercalation processes resulted in a phase transformation of α-V 2 O 5 to NaV 3 O 8. Structural transformation (i.e., orthorhombic to monoclinic crystal structure) and morphological changes were also observed during the electrochemical phase conversion process. This electrochemical phase transformation process improved the overall supercapacitive performance of the α-V 2 O 5 material. Such electrochemically converted NaV 3 O 8 displayed a maximum specific capacitance of 640.1 F g−1 at 0.5 A g−1 with a long cyclic stability. Furthermore, the AC // NaV 3 O 8 asymmetric SC coin cell device delivered a maximum energy density of 62.6 Wh kg−1 and a power density of 7.3 kW kg−1 along with an excellent cycling stability of ∼81 % over 5000 GCD cycles. [ABSTRACT FROM AUTHOR]

Specific surface area and electrical conductivity are two decisive factors affecting materials properties. As a potential energy material, MoO 3 is still limited in research and application due to its inherent defects. Ag nanoparticles with good electrical conductivity and unique small-size effect are predicted to have more hopeful prospects in energy storage. Ag@MoO 3 composites with different Ag content were successfully prepared by a simple liquid-phase reduction method. The results show that the Ag@MoO 3 composite has good morphology and the maximum capacitance (225 F/g) when the content of Ag is 8%. Notably, the internal resistance and Warberg resistance of the composite compared with that of MoO 3 have been greatly reduced. It is mainly due to the high ion conductivity and small-size effect of Ag nanoparticles, which effectively improve the diffusion efficiency of ions between electrolyte and active materials. Practical application feasibility of Ag@MoO 3 electrode was tested in the two-electrode system. Symmetrical coin cell supercapacitor using 8% Ag@MoO 3 as electrodes has superior performance. Our work has potential reference value for the combination and characterization of energy storage materials. [ABSTRACT FROM AUTHOR]

Cycling Li-ion cells with large capacities requires high currents and hence an expensive measurement setup. Aging the Li-ion cell material in coin cells offers an orders-of-magnitude-lower power requirement to the battery tester. The preparation procedure used in this work allows one to build coin cells in a reproducible manner. The original 40Ah pouch cells and the corresponding 4.3mAh coin cells (PAT-Cell) utilizing electrode material from the original cells are cycled with 1C at different temperatures. The results show the same basic aging mechanisms in both cell types: loss of lithium inventory at room temperature but an increasing proportion of loss of active material toward higher temperatures. This is confirmed by similar activation energies in capacity degradation of the 40Ah cells and the averaged coin cells. However, the capacity of the coin cells decreases faster over time. This is caused by diffusion of moisture into the coin cell housing. Nonetheless, the increasing water contamination over measurement time is not directly linked to the loss of capacity of the coin cells. Thus, the observed aging mechanisms of the 40Ah cells can be qualitatively transferred to coin cell level. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional computational fluid dynamics model based on the finite volume method is developed for an anode-supported solid oxide fuel cell with an active area of 1.54 cm2. The numerical model including electrochemical reaction has been compared with experimental data obtained under the same conditions to verify the reliability of the code, air and fuel concentrations at the anode and cathode of the cell were shown and analyzed according to the three fuel utilization rates. The calculated current density of the SOFC has been affected by the flow velocity and gas concentration due to water vapor generation. The electrochemical reaction generates water vapors at the reaction sides which impedes gas diffusion. We have shown the streamlines of gas flow distracted by increased water vapor concentration. Consequently, the operating conditions of SOFC should be determined by considering the effects of water vapor generation for the practical applications. We have verified the water vapor generation in SOFC which significantly affects the performance. [ABSTRACT FROM AUTHOR]

A highly stable and more water-dispersible graphene (WDG) was synthesized using microwave-assisted ball milling technique. The WDG-wrapped MnO2 nanocomposites were prepared for two mass ratios of nanospheres and graphene sheets using reflux method. Comprehensive characterization of the prepared WDG-Mn1 and WDG-Mn2 hybrid nanocomposites was carried out to explore the electrochemical capacitance behaviors. The WDG-Mn1 and WDG-Mn2 electrodes showed capacitance performance of 130 F g−1 at 0.5 A g−1 and 178 F g−1 at 0.5 A g−1, respectively. The WDG-Mn2 electrode revealed enhanced capacitance performance, that is, 84% of its initial capacitance was retained even after repeating the cyclic voltammetry test for 3000 cycles. This study reveals the enhanced capacity performance in WDG-Mn2 nanocomposite hybrid materials for supercapacitors. [ABSTRACT FROM AUTHOR]

• Synthesis of V 2 O 5 via simple thermal decomposition of ammonium metavanadate and glycine. • More than two fold increase in specific capacitance under light for V 2 O 5 ||AC device. • V 2 O 5 ||V 2 O 5 device was charged under light to 200 mV in 1 h. • Outstanding coulombic efficiency of 98% even after 40,000 cycles at a high current density of 10 and 15 mA cm−2. A photo-assisted energy storage system enables a new pathway to utilize unlimited solar energy. Herein, V 2 O 5 was synthesized using a simple, time-saving thermal decomposition process. The V 2 O 5 samples were characterized thoroughly. The photo-electrochemical performances of the as-prepared V 2 O 5 samples were evaluated using a three-electrode system. The material showed increased specific capacity from 45 C g−1 to 69 C g−1 in the presence of light. The photo-assisted V 2 O 5 ||V 2 O 5 and V 2 O 5 ||AC (activated carbon) ASC (asymetric supercapacitors) FTO devices effectively responded to the light sources. The areal capacity of the V 2 O 5 ||AC ASC FTO photo-assisted charging device was 112 mC cm−2 under the given light intensity, whereas the device tested using the conventional process (without light irradiation) delivered only 45 mC cm−2 at the same current density. Further, the asymmetric FTO device delivered high specific energy and power density of 9.8 Wh kg−1, and 29 W kg−1 respectively, in the presence of light. Notably, the symmetric FTO device was photo charged to 200 mV in 1 h without any external current and was discharged in the dark at 0.01 mA cm−2. On the other hand, V 2 O 5 symmetric coin cell delivered excellent cycle stability over 40,000 cycles at different current rates with an outstanding coulombic efficiency of 98%. These results are a clear indication that the photo charging-based supercapacitor will pave an innovative path in constructing futuristic energy storage devices. [ABSTRACT FROM AUTHOR]

Cycling Li-ion cells with large capacities requires high currents and hence an expensive measurement setup. Aging the Li-ion cell material in coin cells offers an orders-of-magnitude-lower power requirement to the battery tester. The preparation procedure used in this work allows one to build coin cells in a reproducible manner. The original 40 Ah pouch cells and the corresponding 4.3 mAh coin cells (PAT-Cell) utilizing electrode material from the original cells are cycled with 1C at different temperatures. The results show the same basic aging mechanisms in both cell types: loss of lithium inventory at room temperature but an increasing proportion of loss of active material toward higher temperatures. This is confirmed by similar activation energies in capacity degradation of the 40 Ah cells and the averaged coin cells. However, the capacity of the coin cells decreases faster over time. This is caused by diffusion of moisture into the coin cell housing. Nonetheless, the increasing water contamination over measurement time is not directly linked to the loss of capacity of the coin cells. Thus, the observed aging mechanisms of the 40 Ah cells can be qualitatively transferred to coin cell level.

In situ characterization techniques have made a significant progress in recent years, especially in the electrochemical field. For Li-ion batteries, in situ characterization techniques refer to using analytical equipment to directly characterize electrode materials during electrochemical measurements. At present, most in situ batteries are developed from commercial simulated batteries, of which the cost is very high and the cycle life is quite short. In this work, two kinds of coin-cell-based in situ batteries were designed as in situ X-ray diffraction (XRD) and Raman coin cells which exhibit many admirable advantages, such as low cost, long cycle life, easy to carry, and so on. In the designing process, in situ XRD and Raman coin cell have been tested with two electrode materials of Li4Ti5O12 and LiFePO4, and we solved many technical problems of assembling and measuring these two kinds of cells. Finally, in situ coin cells could be improved to investigate a variety of electrode materials, and this technique would arouse wide interests in the electrochemical field.

Considering the superior capacitive performance and rich redox kinetics, the two-dimensional (2D) layered molybdenum disulfide (MoS 2 ) and transition metal nitrides (TMNs) have emerged as the latest set of nanomaterials. Direct incorporation of key materials vanadium nitride (VN) and tungsten nitride (W 2 N) into a MoS 2 array has been achieved on cost-effective, bendable stainless steel (SS) foil via a reactive cosputtering route. Herein, we have utilized the synergistic effect of intermixed nanohybrids to develop a flexible asymmetric supercapacitor (FASC) device from MoS 2 -VN@SS (negative) and MoS 2 -W 2 N@SS (positive) electrodes. As-constructed FASC cell possesses a maximum operational potential of 1.80 V and an exceptional gravimetric capacitance of 200 F g -1 at a sweep rate of 5 mV s -1 . The sustained capacitive performance mainly accounts for the synergism induced through unique interfacial surface architecture provided by MoS 2 nanoworms and TMN conductive hosts. The sulfur and nitrogen edges ensure the transport channels to Li + /SO 4 -2 ions for intercalation/deintercalation into the composite nanostructured thin film, further promoting the pseudocapacitive behavior. Consequently, the supercapacitor cell exhibits a distinctive specific energy of 87.91 Wh kg -1 at 0.87 kW kg -1 specific power and a reduced open circuit potential (OCP) decay rate (∼42% self-discharge after 60 min). Moreover, the assembled flexible device exhibits nearly unperturbed electrochemical response even at bending at 165° angle and illustrates a commendable cyclic life-span of 82% after 20,000 charge-discharge cycles, elucidating advanced mechanical robustness and capacitance retentivity. The powering of a multicolor light-emitting diode (LED) and electronic digital watch facilitates the practical evidence to open up possibilities in next-generation state-of-the-art wearable and miniaturized energy storage systems.

Research on the thermal behavior of Li-ion batteries fosters the understanding of heat generating effects and the dimensioning of battery thermal management systems (TMS). First comprehensive studies with a new DSC-like calorimeter for coin-cells are performed to determine thermal properties of a LiCoO 2 -graphite cell. The high precision and accuracy of the measurements are obtained by calibrating the signals using melting point standards in properly prepared coin-cell cases. The heat flow is measured during cycling with different C-rates between 0.23 C and 0.9 C under isothermal conditions at temperatures between 30 °C and 50 °C in steps of 5 K. Chemical and physical changes are identified in the measured heat flow signal and are discussed taking into account phase diagram information. Energetic efficiencies are calculated in dependence of temperature and C-rates by integrating the measured electrical power and heat values. The influence of cell aging on heat generation and usable capacity under operating conditions is shown. Considering the measured heat generation in a wide temperature range at different C-rates will make a valuable contribution to the understanding of material properties. This fundamental data is essential to improve thermal models to simulate spatially resolved heat dissipation in the electrodes to prevent over-heating. [ABSTRACT FROM AUTHOR]

In this work, organic-inorganic composite materials of polyaniline and manganese oxide were synthesized and investigated their electrochemical performance. This composite material was prepared by oxidizing aniline with methyl triphenylphosphonium permanganate as a novel organic oxidant via aqueous, emulsion, and interfacial polymerization pathways. This process led to the formation of polyaniline-sulfate salt (PANI-SA-MnO). Formation of polyaniline-sulfate salt was confirmed from FT-IR, EDAX, and XRD results. Formation of MnO was supported by XRD spectrum. PANI-SA-MnO prepared via emulsion polymerization pathway was obtained in porous nanorod morphology with high conductivity (9.4 S cm) compared to that of the other sample prepared via interfacial pathway (1.7 S cm). Whereas, aqueous polymerization pathway resulted in sheet-like morphology with a conductivity of 0.8 S cm. These composites were used as pseudocapacitive electrode materials. Electrochemical characterization (cyclic voltammetry, charge-discharge, and electrochemical impedance measurement) showed that composite prepared via emulsion polymerization pathway gave better electrochemical performance, and showed good cycling behavior. [ABSTRACT FROM AUTHOR]

[Display omitted] • Binder-free Cr/NiO electrodes prepared by single-step magnetron sputtering. • Synergistic effect of Cr in NiO is highlighted in asymmetric supercapacitor. • Cr doped NiO showed an excellent supercapacitive performance (429 mF cm−2). • Remarkable cycling stability performance over 5,000 cycles. • Aging effect of coin cell was examined after 720 h. • Cr/NiO electrodes can utilized for portable and miniaturized electronic devices. Recently, metal oxides (MOs) have received tremendous interest for flexible energy storage systems: in particular, supercapacitors (SCs). SC electrodes are commonly fabricated via the coating of MOs particles, conductive carbon and binders. However, such electrodes, can weaken the performance of SCs. In this work, binder-free nanocluster Cr-doped NiO thin films are grown on flexible stainless-steel (SS) foils using a one-step co-sputtering technique. The distinctive nanocluster structure of Cr-incorporated NiO thin film electrodes (TFEs) has the benefit of reduced ion diffusion length and good charge transport, and can increase the accessibility of ions onto the active surface area. The developed TFEs are examined in 2 M KOH aqueous electrolyte, demonstrating highest areal capacitance of 429 mF cm−2 (251 mC cm−2). Subsequently, an asymmetric coin cell (ACC) SC is assembled. Even after 5,000 cycles, the developed ACC SC demonstrates exceptional cycling stability. Thereafter, the aging test is conducted after 720 h and reveals good electrochemical performance with minimal capacitance fading. Results reveal that Cr-doped NiO TFEs show excellent electrochemical performance with higher areal capacitance and stability compared to NiO and other metal oxide-based TFEs reported previously. The grown Cr-doped NiO binder-free TFEs are good candidates for high-performance and flexible energy storage systems. [ABSTRACT FROM AUTHOR]

• Synthesis of silver-doped reduced graphene oxide/Pani composite. • Electrochemical measurements of silver-doped reduced graphene oxide/Pani composite. • Supercapacitor analysis of silver-doped reduced graphene oxide/Pani composite and coin cell application. In this study, graphene oxide was synthesized by the Hummers method. Reduced graphene oxide was obtained by the hydrothermal method. Then, silver-doped Reduced Graphene Oxide/Polyaniline (Ag-doped rGO/PANI) composites were synthesized. Some physical analyzes of the synthesized composite materials were made. In the XRD examination, it was understood that the materials generally have polyaniline properties. Electrochemical properties were investigated with electrodes prepared from these composites. Specific capacitance, energy, and power density values were calculated from these measurements. The specific capacitance was measured in the range of 0.5–30 A/g and the highest capacitance value was found to be 379 F/g. From these results, the material containing approximately 17 mass percent silver doped reduced graphene oxide gave better results among composite materials. This composite was the most stable material with results of 286–317 F/g at all applied currents. In addition, a coin cell application was made for this example and its measurements were taken. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Stainless-steel (SS) coin-cell parts are more vulnerable to corrosion than the Al. • SS degradation can accelerate the corrosion of Al current collectors. • Galvanic electron transfer from Al to SS can corrode the Al metal. • MD simulations verify SS and Al's corrosion mechanisms in the imide electrolyte. • SS and Al-free pouch cells with carbon current collector show improved cyclability. F-containing functional electrolytes have been extensively investigated to improve the performance of Li-metal batteries as they generate stable LiF-based solid–electrolyte interphase layers, improving Li deposition/dissolution efficiency. However, these imide-based electrolytes corrode not only the Al current collector but also the stainless steel (SS) component of the coin cell at high operating voltages. Additionally, deciding upon which part of the corrosion has a greater effect on the performance degradation remains a topic of debate. In this study, through systematic cell design exposing SS to LiFSI-based electrolyte, it is found that SS corrosion is a more dominant cause of capacity fading than the Al case. Moreover, the computational study reveals that the electron transfer from Al to SS decomposes FSI– and the resulting byproducts finally corrode Al. To develop stable cells by removing corrosion factors, the SS and Al-free pouch-type cells are proposed by integrating carbon current collectors and locally high-concentration electrolyte and exhibit 430 cycles with a coulombic efficiency of 99.93%. This study demonstrates the importance of careful selection of cell components and systematic cell design to ensure a robust interface at the cathode side, suggesting the necessity to develop a new testing cell to replace the current coin-cell platform. [ABSTRACT FROM AUTHOR]

This paper introduces a binder–free electrode prepared by a facile deposition of C/TiO 2 (Carbon/TiO 2 ) or C/GTiO 2 (Carbon/Graphene–TiO 2 ) on the coin cell anode using poly (methyl methacrylate) (PMMA) as a cheap carbon and binding source without using binders and a current collector. The use of graphene not only presents a conducting support to TiO 2 particles, but also greatly improves the porosity of the electrode relative to pristine TiO 2 or C/TiO 2 . In the lithium–ion battery (LIB) anode, the direct deposition enabled sufficient electrical conductivity of the electrode, the intercalated layer–by–layer (LBL) arrangement of the C/GTiO 2 allowed sufficient Li + accessibility, and the resulting electrode exhibited a higher specific capacity and an excellent rate capability compared to conventional TiO 2 electrodes. Drop testing of the binder–free cells prior to electrochemical testing showed that all cells retained their original specific capacity, rate capability, and cycle stability, thus confirming the strong binding of the binder–free electrodes on the coin cell surface. [ABSTRACT FROM AUTHOR]

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• The power density decreases with increasing cathode diameter for the button cells. • Because the polarization resistances associated with gas diffusion process increases. • The polarization resistance also increases with increasing fuel utilization. • The power density is low for large-scale cells under high fuel utilization. Small-scale planar solid oxide fuel cells (SOFCs) with several centimeters in diameter called "button cells" or "coin cells" are widely used for fundamental research. Although the performance of large-scale cells is inferior to that of button cells, the precise reason is unclear. In the present work, electrochemical impedance spectroscopy (EIS) are performed for button cells with different cathode areas under different fuel utilization, and distribution of relaxation times analysis was conducted to deconvolute the EIS. The power density decreased with increasing cathode diameter for the button cells. The polarization resistances associated with the gas diffusion process at low frequencies increased for a cell with a large cathode area, when the gas flow path is different between the inner and outer electrode areas for the button cells. The polarization resistance related to the gas diffusion process also increases with increasing fuel utilization. As a result of simple simulation considering the Nernst loss, the power density at 0.75 V was estimated to be 0.169 W/cm2 at U f = 0.8 for a large-scall cell with dimensions of 10 × 10 cm2, which is smaller than that for a button cell with a cathode diameter of 6 mm (0.730 W/cm2 at U f = 0.04). [Display omitted] [ABSTRACT FROM AUTHOR]