Work on solid electrolytes for rechargeable lithium-based batteries is motivated by the potential benefits of lithium-metal anodes for a variety of applications, including electric vehicles. Dendrite formation has been the key challenge preventing commercialization of rechargeable lithium-metal batteries, so establishing, validating, and improving the dendrite resistance of electrolytes is a key enabler of progress in the field. Typical symmetric cycling tests of Li-Li cells introduce operational and theoretical limitations which compromise the data produced and the conclusions which can be drawn from such testing. A high-throughput technique for unidirectional critical current density testing is presented which has allowed the development of a solid electrolyte capable of withstanding current densities of at least 300 mA cm−2. The theoretical and empirical basis for this testing methodology is outlined, results are presented and analyzed, and best practices for critical current density testing of solid electrolyte materials are proposed.
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The Electrochemical Society (ECS) was founded in 1902 to advance the theory and practice at the forefront of electrochemical and solid state science and technology, and allied subjects.
ISSN: 1945-7111
JES is the flagship journal of The Electrochemical Society. Published continuously from 1902 to the present, JES remains one of the most highly-cited journals in electrochemistry and solid-state science and technology.
Danielle M. Gendron et al 2025 J. Electrochem. Soc. 172 020511
Eniko S. Zsoldos et al 2024 J. Electrochem. Soc. 171 080527
Lithium iron phosphate (LFP) battery cells are ubiquitous in electric vehicles and stationary energy storage because they are cheap and have a long lifetime. This work compares LFP/graphite pouch cells undergoing charge-discharge cycles over five state of charge (SOC) windows (0%–25%, 0%–60%, 0%–80%, 0%–100%, and 75%–100%). Cycling LFP cells across a lower average SOC results in less capacity fade than cycling across a higher average SOC, regardless of depth of discharge. The primary capacity fade mechanism is lithium inventory loss due to: lithiated graphite reactivity with electrolyte, which increases incrementally with SOC, and lithium alkoxide species causing iron dissolution and deposition on the negative electrode at high SOC which further accelerates lithium inventory loss. Our results show that even low voltage LFP systems (3.65 V) have a tradeoff between average SOC and lifetime. Operating LFP cells at lower average SOC can extend their lifetime substantially in both EV and grid storage applications.
Toby Bond et al 2024 J. Electrochem. Soc. 171 110514
As service lifetimes of electric vehicle (EV) and grid storage batteries continually improve, it has become increasingly important to understand how cells perform after extensive cycling. The multifaceted nature of degradation in Li-ion cells can lead to complex behavior that may be difficult for battery management systems or operators to model. Accurate characterization of heavily cycled cells is critical for developing accurate models, especially for cycle-intensive applications like second-life grid storage or vehicle-to-grid charging. In this study, we use operando synchrotron x-ray diffraction (SR-XRD) to characterize a commercially manufactured polycrystalline NMC622 pouch cell that was cycled for more than 2.5 years. Using spatially resolved synchrotron XRD, the complex kinetics and spatially heterogeneous behavior of such cells are mapped and characterized under both near-equilibrium and non-equilibrium conditions. The resulting data is complex and multifaceted, requiring a different approach to analysis and modelling than what has been used in the literature. To show how material selection can impact the extent of degradation, we compare the results from polycrystalline NMC622 cells to an extensively cycled single-crystal NMC532 cell with over 20,000 cycles—equivalent to a total EV traveled distance of approximately 8 million km (5 million miles) over six years.
Peter Keil et al 2016 J. Electrochem. Soc. 163 A1872
In this study, the calendar aging of lithium-ion batteries is investigated at different temperatures for 16 states of charge (SoCs) from 0 to 100%. Three types of 18650 lithium-ion cells, containing different cathode materials, have been examined. Our study demonstrates that calendar aging does not increase steadily with the SoC. Instead, plateau regions, covering SoC intervals of more than 20%–30% of the cell capacity, are observed wherein the capacity fade is similar. Differential voltage analyses confirm that the capacity fade is mainly caused by a shift in the electrode balancing. Furthermore, our study reveals the high impact of the graphite electrode on calendar aging. Lower anode potentials, which aggravate electrolyte reduction and thus promote solid electrolyte interphase growth, have been identified as the main driver of capacity fade during storage. In the high SoC regime where the graphite anode is lithiated more than 50%, the low anode potential accelerates the loss of cyclable lithium, which in turn distorts the electrode balancing. Aging mechanisms induced by high cell potential, such as electrolyte oxidation or transition-metal dissolution, seem to play only a minor role. To maximize battery life, high storage SoCs corresponding to low anode potential should be avoided.
George E. Blomgren 2017 J. Electrochem. Soc. 164 A5019
This year, the battery industry celebrates the 25th anniversary of the introduction of the lithium ion rechargeable battery by Sony Corporation. The discovery of the system dates back to earlier work by Asahi Kasei in Japan, which used a combination of lower temperature carbons for the negative electrode to prevent solvent degradation and lithium cobalt dioxide modified somewhat from Goodenough's earlier work. The development by Sony was carried out within a few years by bringing together technology in film coating from their magnetic tape division and electrochemical technology from their battery division. The past 25 years has shown rapid growth in the sales and in the benefits of lithium ion in comparison to all the earlier rechargeable battery systems. Recent work on new materials shows that there is a good likelihood that the lithium ion battery will continue to improve in cost, energy, safety and power capability and will be a formidable competitor for some years to come.
Yuliya Preger et al 2020 J. Electrochem. Soc. 167 120532
Energy storage systems with Li-ion batteries are increasingly deployed to maintain a robust and resilient grid and facilitate the integration of renewable energy resources. However, appropriate selection of cells for different applications is difficult due to limited public data comparing the most commonly used off-the-shelf Li-ion chemistries under the same operating conditions. This article details a multi-year cycling study of commercial LiFePO4 (LFP), LiNixCoyAl1−x−yO2 (NCA), and LiNixMnyCo1−x−yO2 (NMC) cells, varying the discharge rate, depth of discharge (DOD), and environment temperature. The capacity and discharge energy retention, as well as the round-trip efficiency, were compared. Even when operated within manufacturer specifications, the range of cycling conditions had a profound effect on cell degradation, with time to reach 80% capacity varying by thousands of hours and cycle counts among cells of each chemistry. The degradation of cells in this study was compared to that of similar cells in previous studies to identify universal trends and to provide a standard deviation for performance. All cycling files have been made publicly available at batteryarchive.org, a recently developed repository for visualization and comparison of battery data, to facilitate future experimental and modeling efforts.
Manuel Ank et al 2023 J. Electrochem. Soc. 170 120536
Battery research depends upon up-to-date information on the cell characteristics found in current electric vehicles, which is exacerbated by the deployment of novel formats and architectures. This necessitates open access to cell characterization data. Therefore, this study examines the architecture and performance of first-generation Tesla 4680 cells in detail, both by electrical characterization and thermal investigations at cell-level and by disassembling one cell down to the material level including a three-electrode analysis. The cell teardown reveals the complex cell architecture with electrode disks of hexagonal symmetry as well as an electrode winding consisting of a double-sided and homogeneously coated cathode and anode, two separators and no mandrel. A solvent-free anode fabrication and coating process can be derived. Energy-dispersive X-ray spectroscopy as well as differential voltage, incremental capacity and three-electrode analysis confirm a NMC811 cathode and a pure graphite anode without silicon. On cell-level, energy densities of 622.4 Wh/L and 232.5 Wh/kg were determined while characteristic state-of-charge dependencies regarding resistance and impedance behavior are revealed using hybrid pulse power characterization and electrochemical impedance spectroscopy. A comparatively high surface temperature of ∼70 °C is observed when charging at 2C without active cooling. All measurement data of this characterization study are provided as open source.
Chang-Hui Chen et al 2020 J. Electrochem. Soc. 167 080534
Presented here, is an extensive 35 parameter experimental data set of a cylindrical 21700 commercial cell (LGM50), for an electrochemical pseudo-two-dimensional (P2D) model. The experimental methodologies for tear-down and subsequent chemical, physical, electrochemical kinetics and thermodynamic analysis, and their accuracy and validity are discussed. Chemical analysis of the LGM50 cell shows that it is comprised of a NMC 811 positive electrode and bi-component Graphite-SiOx negative electrode. The thermodynamic open circuit voltages (OCV) and lithium stoichiometry in the electrode are obtained using galvanostatic intermittent titration technique (GITT) in half cell and three-electrode full cell configurations. The activation energy and exchange current coefficient through electrochemical impedance spectroscopy (EIS) measurements. Apparent diffusion coefficients are estimated using the Sand equation on the voltage transient during the current pulse; an expansion factor was applied to the bi-component negative electrode data to reflect the average change in effective surface area during lithiation. The 35 parameters are applied within a P2D model to show the fit to experimental validation LGM50 cell discharge and relaxation voltage profiles at room temperature. The accuracy and validity of the processes and the techniques in the determination of these parameters are discussed, including opportunities for further modelling and data analysis improvements.
Vivian Murray et al 2019 J. Electrochem. Soc. 166 A329
The development of new positive electrode materials is on route to increase the energy density of lithium-ion batteries (LIBs) for electric vehicle and grid storage applications. The performance of new materials is typically evaluated using hand-made half coin cells with the new material as the positive electrode and a piece of lithium foil for the negative. Whereas half coin cells are easy to make and can give reproducible data, they can fail to accurately predict how a material would perform in a full cell. The present work develops methods to prepare full coin cells, using graphite as the negative electrode material. Detailed instructions are provided to enable researchers to prepare their own high quality full coin cells with good reproducibility between cells. The precision of the hand-made full coin cells is compared with and found to approach the quality of machine-made, commercially produced full cells.
Nagappan Ramaswamy et al 2025 J. Electrochem. Soc. 172 024501
Catalyst requirements for proton exchange membrane (PEM) fuel cells differ by applications. Commercial heavy-duty vehicle (HDV) applications consume more H2 fuel and demand higher durability than many others and the total cost of ownership (TCO) of the vehicle is largely related to the performance and durability of catalysts. This article is written to bridge the gap between the industrial requirements and academic activity for advanced cathode catalysts with an emphasis on durability. From a materials perspective, the underlying nature of the carbon support, Pt-alloy crystal structure, stability of the alloying element, cathode ionomer volume fraction, and catalyst-ionomer interface play a critical role in improving performance and durability. We provide our perspective on four major approaches, namely, mesoporous carbon supports, ordered PtCo intermetallic alloys, thrifting ionomer volume fraction, and shell-protection strategies that are currently being pursued. While each approach has its merits and demerits, their key developmental needs for future are highlighted.
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Farhanini Yusoff et al 2025 J. Electrochem. Soc. 172 026506
The development of cost-effective and efficient electrocatalysts for the hydrogen evolution reaction (HER) is essential for advancing hydrogen production technologies. This study explores iron/reduced graphene oxide (Fe-rGO) nanocomposites synthesized using a facile one-pot method, focusing on the impact of varying iron content (1, 5, and 10%) on their physicochemical and electrochemical properties. Comprehensive characterization using Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy-energy-dispersive X-ray analysis, transmission electron microscopy, and Brunnauer-Emmett-Teller analysis confirmed the successful integration of iron into the graphene matrix, with distinct structural changes and mesoporosity observed across samples. Thermal stability was affirmed via thermogravimetric analysis. Electrochemical performance was evaluated by fabricating Fe-rGO-modified glassy carbon electrodes (Fe-rGO/GCE), which showed significantly enhanced current response compared to unmodified GCE, attributed to improved electron transfer dynamics and reduced charge transfer resistance. Among the composites, Fe-rGO/GCE 10% demonstrated the best performance and the lowest charge transfer resistance (166.3 Ω·cm), indicating a rapid electron transfer mechanism. Comparative analysis confirmed that 10% Fe/GCE outperformed other electrodes, highlighting the beneficial effect of iron incorporation on HER activity. These findings suggest that Fe-rGO nanocomposites hold significant potential as non-precious metal electrocatalysts for HER, offering a promising alternative to platinum-based catalysts in hydrogen production.
Gerard Bree et al 2025 J. Electrochem. Soc. 172 020526
The reduction of battery charge times is a key challenge in the wider adoption of electric vehicles (EVs), encompassing material, cell, and system design aspects. Rate capability testing, the charging and discharging of a cell at various C-rates, is the most common technique used to assess the performance of Li-ion batteries, and particularly new electrode materials/cell designs, at high cycling rates. Data generated from this technique is extremely sensitive to selected cell format, quality of assembly, and test protocols, and thus lack of standardisation prevents both robust conclusions and comparison between studies. Furthermore, the figures of merit of such studies are often ill-defined, out of step with commercial requirements and established only for non-relevant formats. Herein, we utilise LiMn0.6Fe0.4PO4\\Graphite (LMFP\\Gr) coin (half and full) and full pouch cells to demonstrate these sensitivities. Cell format, electrode coat weight/porosity, and the inclusion of a constant voltage step during charge, are shown to dramatically alter the capacity observed at high C-rate in otherwise identical cells, reinforcing the advantages of testing in real-world conditions and the need for consistency between test samples/studies. To resolve this, we propose a commercially meaningful and industrially relevant protocol to evaluate fast-charging capabilities of Li-ion batteries.
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Highlights
Academic battery testing involves non-standard parameters out of step with industry
LMFP coin and pouch cells are manufactured and tested for rate capability
The role of manufacturing parameters and test protocol are highlighted and quantified
A new protocol is proposed for a more meaningful assessment of Li-ion cells
Michiyo Nakatsu et al 2025 J. Electrochem. Soc. 172 027513
Herein, we report a biochemical corrosion-monitoring (BCM) sensor for detecting live E.coli. To analyze the current generation mechanism in the H2S response of the Ag/C sensor, we investigated the Ag2S film deposited on the Ag electrode surface after the H2S response. XPS surface analysis confirmed that the film deposited on the Ag electrode surface had a single composition of Ag2S. The Ag2S film thickness of 23 nm estimated by XPS depth analysis and the Ag2S deposition range of 0–12 μm estimated from cathodic reduction stripping experiments significantly agreed with the Ag2S film thickness and deposition calculated from the electrical quantity of the sensor. Therefore, it was concluded that all the reaction charges of the sulfurization reaction of the Ag/C sensor were converted into galvanic current (Igal), and the Igal generation of the Ag/C sensor in the E.coli solution was due to the sulfurization reaction of the Ag electrode. The Ag2S film can be removed by constant current electrolysis or by dissolution using a sulfuric acid solution containing thiourea. The Igal change in the E.coli solution of each sensor from which the Ag2S film was once removed was the same as that of an unused sensor.
Serin Lee et al 2025 J. Electrochem. Soc. 172 022506
The ability to control the rate and nature of electrochemical deposition at different locations on a single electrode could enable pattern generation and the formation of functional structures with dimensions that are smaller than the electrodes themselves. Here we explore the kinetics of this effect by incorporating a heater beneath an electrode to increase the deposition rate locally. For galvanostatic copper deposition from acidified copper sulphate, we perform deposition in a liquid cell in the transmission electron microscope to measure the deposited thickness as a function of time. We show that the Cu deposition rate can double for a temperature rise of 20 °C, but the enhancement occurs only at early times, after which the growth rate converges to the unheated value. We model the factors responsible for the enhancement and conclude that the excess material deposited is limited by diffusion. We discuss opportunities for deposition patterned in this way to control thickness, composition or structure.
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Samiksha Dabas et al 2025 J. Electrochem. Soc. 172 027512
Multiferroic (MF) and magnetoelectric (ME) materials are highly sought after by researchers in the quest for fabrication, design, and functioning of novel, precise, low-noise next-generation sensing technologies. We provide a succinct perspective on usage of MEs and MFs in sensing applications including antenna, magnetic field and current sensing, bio-magnetic sensing, proximity sensing or motion detection, tactile sensor with robotic arms to measure mechanical properties of target, piezoelectric nanogenerator, magneto-mechano-electrical energy generator device, and gas sensing. The current developments in 2D MFs have also reinvigorated researchers' interest towards miniaturized electronics and "multiferroic magnonics" for future low power consumption and low noise computing.
Zhouyang Bai et al 2025 J. Electrochem. Soc. 172 021504
Subcritical and supercritical water systems, critical in nuclear energy, thermal power, and pollutant treatment, operate under extreme conditions that intensify material corrosion. In-situ electrochemical monitoring provides essential real-time data for optimizing operational conditions and enhancing corrosion prediction models. This paper evaluates high-temperature electrochemical monitoring techniques, focusing on the performance of reference electrodes and research platforms. While hydrogen electrodes offer precision, their operational complexity limits practicality. Metal/metal oxide electrodes provide robustness but suffer from potential instability, and yttria-stabilized zirconia electrodes, though suitable for high temperatures, are fragile and challenging to fabricate. External pressure-balanced reference electrodes and flow-through versions represent promising alternatives but require further refinement, particularly in thermal liquid junction potential calibration. The development of advanced research platforms, facilitating in situ electrochemical testing via techniques like electrochemical impedance spectroscopy and potentiodynamic polarization curves, is also discussed. The point defect model and its supercritical water adaptation provide a robust framework for understanding corrosion mechanisms at the microstructural level. Ongoing innovation in electrode design, platform scalability, and diagnostic techniques will be essential to advancing corrosion monitoring in extreme environments, ensuring enhanced material performance and operational safety.
M. K. Nahian and R. G. Reddy 2025 J. Electrochem. Soc. 172 022503
Lanthanides are rare Earth elements (REEs) positioned in the f-block of the periodic table and exhibit unique electronic configurations that confer exceptional magnetic, optical, and electronic properties. Consequently, they are pivotal components spanning from hard disk drives to renewable energy systems. The increasing demand for REEs in various modern technologies has driven the need for a secure and sustainable production process. Traditional methods of REEs extraction and processing, such as molten salt electrolysis, are energy-intensive and generate toxic waste, necessitating the development of alternative low-temperature separation processes. Ionic liquids (ILs), or low-temperature molten salts, have emerged as promising media for REEs electrodeposition owing to their wide potential window, excellent ionic conductivity, thermal stability, and environmental friendliness. In this review, electrochemical behavior and electrodeposition of some common REEs (Y, La, Pr, Nd, Sm, Eu, Gd, and Dy) in various ILs, along with selected cases of similar types of electrolytes called deep eutectic solvents (DESs), are discussed. The comprehensive analysis of the electrochemical behavior and deposition conditions of REEs in ILs offers valuable insights into sustainable industrial-scale REEs production in an environment-friendly way.
Abdel-Aziz B. Abdel-Aziz et al 2025 J. Electrochem. Soc. 172 023503
Metal oxides and mixed metal oxide nanoparticles (MMONPs) have gained significant attention due to their unique properties and potential applications in various fields. In this review, the recent advancements in this area will be noted. The diverse synthetic techniques, including thermal deposition, sol-gel deposition, electrodeposition, spin coating, and microwave-assisted synthesis, choice of preparation method and the importance of controlling various synthesis parameters, such as temperature, pH, and precursor concentration, their impact on the prepared metal oxides' size, shape, and composition will be correlated. A comprehensive overview of various characterization techniques, such as physical and chemical (SEM, EDS, TEM, AFM, DLS, XRD, and XPS), electrochemical (EIS, CV, SECM, and Zeta-potential), thermal (TGA), and optical (FTIR, UV–vis spectroscopy, and Raman spectroscopy), and their crucial role in understanding the structural and morphological properties of the prepared metal oxide materials will be explained. This review also highlights the recent advancements, in the past decade, involving the application of MMONPs in electrolysis, catalysis, fuel cells, environmental remediation, and biosensing applications will be highlighted, as well as, their role as a dimensional stable anode (DSA) for the chlor-alkali industry and electrocatalytic enhance for the electrooxidation reactions in direct liquid fuel cell applications.
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Highlights
Metal oxides and mixed metal oxide nanoparticles (MMONPs) have unique properties and promising Electrochemical applications.
The impact of the used synthesis approach on the prepared metal oxides' size, shape, and composition will be indicated.
The application of MMONPs in electrolysis, catalysis, fuel cells, environmental remediation, and biomedical applications will be highlighted.
The role of MMONPs as a dimensional stable anode (DSA) for the chlor-alkali industry and electrocatalytic efficiency in direct liquid fuel cell applications will be evaluted.
Yong Wen Chek et al 2025 J. Electrochem. Soc. 172 020509
Separator membrane is an essential element within every battery system, having a significant influence on both safety and electrochemical performance. With rejuvenated interest in rechargeable alkaline zinc batteries, such as zinc-air, nickel-zinc (NiZn), and zinc-manganese (Zn-MnO2) batteries, there has been an increased focus on scrutinizing the role of each component in the battery system, including the separator. This scrutiny arises from the realization that separator properties are vital for influencing battery cycle life, discharge capacity, rate capability, and capacity retention. Various types of separators have been thoroughly investigated for their suitability in rechargeable alkaline zinc batteries, including nonwoven, microporous, inorganic, and polymer electrolyte membranes. Primary challenges associated with rechargeable alkaline zinc batteries are zincate ion crossover and dendrite penetration of the separator, both of which are known to adversely affect the battery performance and safety. Significant efforts have been dedicated to modifying conventional membranes, as well as to develop new separators tailored to address the challenges encountered by these battery systems. This review provides comprehensive overview on the challenges in development of alkaline zinc batteries, different types of separators utilized in rechargeable alkaline zinc batteries, and the optimization strategies employed to enhance battery performance.
Nagappan Ramaswamy et al 2025 J. Electrochem. Soc. 172 024501
Catalyst requirements for proton exchange membrane (PEM) fuel cells differ by applications. Commercial heavy-duty vehicle (HDV) applications consume more H2 fuel and demand higher durability than many others and the total cost of ownership (TCO) of the vehicle is largely related to the performance and durability of catalysts. This article is written to bridge the gap between the industrial requirements and academic activity for advanced cathode catalysts with an emphasis on durability. From a materials perspective, the underlying nature of the carbon support, Pt-alloy crystal structure, stability of the alloying element, cathode ionomer volume fraction, and catalyst-ionomer interface play a critical role in improving performance and durability. We provide our perspective on four major approaches, namely, mesoporous carbon supports, ordered PtCo intermetallic alloys, thrifting ionomer volume fraction, and shell-protection strategies that are currently being pursued. While each approach has its merits and demerits, their key developmental needs for future are highlighted.
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Guoxin Li et al 2025 J. Electrochem. Soc. 172 026501
Cathode-electrolyte interphase (CEI) is critical for inhibiting the cathode degradation to maintain cell life. However, the evolution of the CEI is still unclear due to its complex and slow dynamic process. Here we used scanning electrochemical microscopy (SECM) for in situ investigation of CEI formation process on LiFePO4 cathode. Feedback images and probe scan curves showed a heterogeneous passivation that was gently generated on the LiFePO4 particles during both charging and discharging. Besides, a LiFePO4 composited electrode was also used to investigate the CEI formation to simulate the condition of real battery system. The composited cathode does not show obvious CEI formation within first two cycles. The SECM results between the pristine LiFePO4 particles and the composited LiFePO4 indicated the dynamic accumulation of CEI, which is influenced by the ability to charge transfer kinetics of cathode materials. This approach provided a feasible consideration for the connections between the dynamic evolution of the CEI and changes in charge transfer capability of cathode during cycling.
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Highlights
In-situ investigation of cathode-electrolyte interphase formation.
The evolution of native active material and composite slurry were compared.
The electrochemical activity change upon cathode cycling are analysed in situ.
The influence of the charge transfer capability upon CEI generation is revealed.
D. Noel Buckley and Johna Leddy 2024 J. Electrochem. Soc. 171 116503
We revisit the classical derivation of the Butler-Volmer equation to include the effect of the electrode metal. If the metal is replaced by one with a different work function, keeping other conditions in the electrode constant, the chemical potential of electrons and the Galvani potential
change in a complementary manner. Changes in
and
each impact the free energies of activation of the forward and backward electron transfer reactions, so we modify the classical expressions which relate them to applied voltage E by including also the effect of
Inserting these expressions in an Eyring-Polyani or Arrhenius type equation in the traditional way, we obtain a modified Butler-Volmer equation which expresses current density as a function of both
and
The exchange current density
appears as an exponential function of
For the work function
of the metal, the approximation
yields a linear relationship between
and
The linear increase in
with
has long been reported. We show two experimental examples: the aqueous Fe2+/Fe3+ couple with positive slope and the hydrogen evolution reaction (HER) with parallel lines for the d and sp metals, both with positive slopes.
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Philip Minnmann et al 2024 J. Electrochem. Soc. 171 060514
The kinetics of composite cathodes for solid-state batteries (SSBs) relies heavily on their microstructure. Spatial distribution of the different phases, porosity, interface areas, and tortuosity factors are important descriptors that need accurate quantification for models to predict the electrochemistry and mechanics of SSBs. In this study, high-resolution focused ion beam-scanning electron microscopy tomography was used to investigate the microstructure of cathodes composed of a nickel-rich cathode active material (NCM) and a thiophosphate-based inorganic solid electrolyte (ISE). The influence of the ISE particle size on the microstructure of the cathode was visualized by 3D reconstruction and charge transport simulation. By comparison of experimentally determined and simulated conductivities of composite cathodes with different ISE particle sizes, the electrode charge transport kinetics is evaluated. Porosity is shown to have a major influence on the cell kinetics and the evaluation of the active mass of electrochemically active particles reveals a higher fraction of connected NCM particles in electrode composites utilizing smaller ISE particles. The results highlight the importance of homogeneous and optimized microstructures for high performance SSBs, securing fast ion and electron transport.
S. Yanev et al 2024 J. Electrochem. Soc. 171 020512
Li-In electrodes are widely applied as counter electrodes in fundamental research on Li-metal all-solid-state batteries. It is commonly assumed that the Li-In anode is not rate limiting, i.e. the measurement results are expected to be representative of the investigated electrode of interest. However, this assumption is rarely verified, and some counterexamples were recently demonstrated in literature. Herein, we fabricate Li-In anodes in three different ways and systematically evaluate the electrochemical properties in two- and three-electrode half-cells. The most common method of pressing Li and In metal sheets together during cell assembly resulted in poor homogeneity and low rate performance, which may result in data misinterpretation when applied for investigations on cathodic phenomena. The formation of a Li-poor region on the separator side of the anode is identified as a major kinetic bottleneck. An alternative fabrication of a Li-In powder anode resulted in no kinetic benefits. In contrast, preparing a composite from Li-In powder and sulfide electrolyte powder alleviated the kinetic limitation, resulted in superior rate performance, and minimized the impedance. The results emphasize the need to fabricate optimized Li-In anodes to ensure suitability as a counter electrode in solid-state cells.
Highlights
The fabrication of Li-In anodes needs to be optimized to ensure suitability as a counter electrode in sulfide all-solid-state batteries.
The Li-In counter electrode may often be the limiting factor of sulfide all-solid-state halfcells.
Pressing Li and In foil together results in a kinetically limited anode.
Composites from Li-In and sulfide electrolyte result in stable reference potential, superior rate performance and low impedance of the counter electrode.
Ramver Singh et al 2024 J. Electrochem. Soc. 171 013501
Electrical discharge micromachining (EDM) poses challenges to the fatigue-life performance of machined surfaces due to thermal damage, including recast layers, heat-affected zones, residual stress, micro-cracks, and pores. Existing literature proposes various ex situ post-processing techniques to mitigate these effects, albeit requiring separate facilities, leading to increased time and costs. This research involves an in situ sequential electrochemical post-processing (ECPP) technique to enhance the quality of EDMed micro-holes on titanium. The study develops an understanding of the evolution of overcutting during ECPP, conducting unique experiments that involve adjusting the initial radial interelectrode gap (utilizing in situ wire-electrical discharge grinding) and applied voltage. Additionally, an experimentally validated transient finite element method (FEM) model is developed, incorporating the passive film formation phenomenon for improved accuracy. Compared to EDM alone, the sequential EDM-ECPP approach produced micro-holes with superior surface integrity and form accuracy, completely eliminating thermal damage. Notably, surface roughness (Sa) was reduced by 80% after the ECPP. Increasing the voltage from 8 to 16 V or decreasing the gap from 60 to 20 μm rendered a larger overcut. This research's novelty lies in using a two-phase dielectric (water-air), effectively addressing dielectric and electrolyte cross-contamination issues, rendering it suitable for commercial applications.
Highlights
Better micro-hole quality through in situ sequential eco-friendly near-dry EDM & ECM
Successfully resolved dielectric-electrolyte cross-contamination in sequential processes
Unique experiments that adjust the initial radial IEG using in situ wire-EDG
Developed and validated a transient FEM model, incorporating passivation aspect
Achieved recast layer-free holes with Sa values approximately 80% lower than EDM holes
Daimon et al
Pore structure of mesoporous carbon (MPC, CNovel) as support material for Pt catalysts in polymer electrolyte fuel cells and durability improvement of MPC by heat-treatment were investigated. Because the primary particle size of MPC is ~2 µm, MPC is bead-milled to about 800 nm. Surface area of MPC is 1338 m2 g-1, which is comparable to that of conventional porous carbon support KB-600JD 1350 m2 g-1, while internal surface area of MPC is 1253 m2 g-1, much larger than that of KB-600JD (716 m2 g-1). Mesopore size distribution of MPC is narrower than that of KB-600JD, with central mesopore size of 4 nm. 3D-TEM analysis shows that MPC has much higher density of interconnected mesopores (2-6 nm) than KB-600JD, and cross-sectional scanning electron microscopy observations indicate that macropores (> 50 nm) coexist in MPC. These pore structures contribute to higher cell voltage of Pt/MPC over Pt/KB-600JD in the entire current density region. MPC support is heat-treated at 1800-2400℃ in Ar to improve durability against high potentials (1.0-1.5 V vs. RHE). Durability of Pt/MPC is higher than that of Pt/KB-600JD and monotonically improves with increasing heat-treatment temperature. MPC support maintains high surface area of 800 m2 g-1 even after heat-treatment at 2200°C
Sert et al
In this study, machine learning (ML) algorithms were employed to predict analyte concentrations using sensing results and evaluate the anticancer effects of nanostructures. Multifunctional oolong tea extract-mediated silver nanoparticles (OTE-Ag NPs) were synthesized via a photo/ultrasound method and utilized in various applications, including a smartphone-based H2O2 sensor and electrochemical sensors for urea and fructose. Key features were extracted from electrochemical results, and feature importance analysis was used to select the most predictive features. The artificial neural network (ANN) model provided accurate predictions, particularly strong for urea (R²=0.8575, RMSE=0.4266, MAE=0.3380). The study revealed the selective toxicity of OTE-Ag NPs to MCF-7 breast cancer cells through analyses of cytotoxicity, apoptosis, cell cycle phases, and CD44 surface marker expression using Annexin V/PI dye and flow cytometry. Experimental results demonstrated that OTE-Ag NPs suppressed MCF-7 cell proliferation while exhibiting lower cytotoxicity in normal HUVEC cells (46% cell death). OTE-Ag NPs arrested MCF-7 cells in the G2/M phase, induced apoptosis, and reduced CD44 expression, suggesting metastasis suppression. The CD44+/CD24- ratio decreased from 84.79% in control MCF-7 cells to 47.7% in OTE-Ag NP-treated cells. Overall, OTE-Ag NPs significantly inhibited MCF-7 cell proliferation through the apoptotic pathway by regulating the cell cycle in the G2/M phase.
Shruthi et al
A nano-composition of graphene oxide (GO), copper oxide (CuO), and zinc oxide (ZnO) was synthesized by utilizing the co-precipitation method and characterized by various methods. The synthesized GO/CuO/ZnO nanocomposite was utilized as a modifier combined with carbon fiber (CF) on the glassy carbon electrode (GO/CuO/ZnO@CF/GCE). The modified electrode was utilized to determine the antibiotic chloramphenicol (CAP), which risks public and environmental health by arising as residue, especially in food samples. Cyclic voltammetry and differential voltammetric techniques were used to investigate the electrochemical performance of CAP on the GO/CuO/ZnO@CF/GCE, and it established excellent electrocatalytic activity compared to bare glassy carbon electrode (BGCE). The electroactive surface area of BGCE and GO/CuO/ZnO@CF/GCE were found to be 0.03605 cm2 and 0.05215 cm2 respectively. Scan-rate studies reveal the diffusion-controlled electrode process at GO/CuO/ZnO@CF/GCE. The modified electrode showed a high sensitivity of 1.45 µA/µM cm2 with a low detection limit (13.3 µM). The prepared modified electrochemical sensor had well repeatability and reproducibility, adequate stability, and good selectivity toward the determination of CAP. Moreover, prepared (GO/CuO/ZnO@CF/GCE) was utilized to measure CAP in real samples such as milk and honey.
mp et al
Hydrogen peroxide (H₂O₂) is a prominent biomarker that is related to oxidative stress in humans and has been utilized in the early diagnosis of diseases like Alzheimer's, diabetes, cardiovascular conditions, and cellular damage. In this research, an inexpensive CuO electrode was developed by electrochemical anodization techniques specifically for H₂O₂ detection. The phase and nanostructured morphology of the electrode were verified using field-emission scanning electron microscopy imaging and X-ray diffraction analysis, while its sensing performance was measured using the amperometric method. The sensitivity of the CuO electrode was significantly enhanced up to 3.1 mA mM⁻¹ cm⁻² with a detection limit of 10 µM in 0.1 seconds. The flat band potential, ranging from 0.246 to 0.259 V, was seen through Mott-Schottky measurements. Charge transfer resistance in the Nyquist plots ranges from 7.32 to 9.09 Ω, showing good electron transfer of the material. Moreover, stability was found at 87.2% after one month and significant reproducibility across the electrodes. These results emphasize the promise of the CuO electrode as a robust, high-performance, and scalable sensor for the detection of H₂O₂ for oxidative stress monitoring.
Loganathan et al
Cortisol is a key factor in developmental and behavioural research, measured widely in blood, urine, and saliva. Electrochemical sensing has emerged as a reliable technique in the development of point-of-care devices for detecting cortisol. Here, a ZnO/Graphene coated graphite was used as a sensing electrode for the detection of cortisol. The performance of the sensing electrode was tested in the presence of cortisol using electrochemical techniques and the impact of scan rate, concentration, cycle numbers, linear range, and limit of detection is reported. The fabricated ZnO/Graphene/PGE sensing electrode demonstrated excellent performance for cortisol detection, exhibiting a linear response over a wide concentration range of 10.874 to 173.981 mg/ml and a low limit of detection of 6.162 μg/ml. Additionally, the sensor displayed high stability over 60 days, with good repeatability and reproducibility. This shows that the ZnO/Graphene nanocomposite can be used as a non-enzymatic sensor providing a more reliable and effective cortisol sensing.
Gerard Bree et al 2025 J. Electrochem. Soc. 172 020526
The reduction of battery charge times is a key challenge in the wider adoption of electric vehicles (EVs), encompassing material, cell, and system design aspects. Rate capability testing, the charging and discharging of a cell at various C-rates, is the most common technique used to assess the performance of Li-ion batteries, and particularly new electrode materials/cell designs, at high cycling rates. Data generated from this technique is extremely sensitive to selected cell format, quality of assembly, and test protocols, and thus lack of standardisation prevents both robust conclusions and comparison between studies. Furthermore, the figures of merit of such studies are often ill-defined, out of step with commercial requirements and established only for non-relevant formats. Herein, we utilise LiMn0.6Fe0.4PO4\\Graphite (LMFP\\Gr) coin (half and full) and full pouch cells to demonstrate these sensitivities. Cell format, electrode coat weight/porosity, and the inclusion of a constant voltage step during charge, are shown to dramatically alter the capacity observed at high C-rate in otherwise identical cells, reinforcing the advantages of testing in real-world conditions and the need for consistency between test samples/studies. To resolve this, we propose a commercially meaningful and industrially relevant protocol to evaluate fast-charging capabilities of Li-ion batteries.
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Highlights
Academic battery testing involves non-standard parameters out of step with industry
LMFP coin and pouch cells are manufactured and tested for rate capability
The role of manufacturing parameters and test protocol are highlighted and quantified
A new protocol is proposed for a more meaningful assessment of Li-ion cells
Hideo Daimon et al 2025 J. Electrochem. Soc.
Pore structure of mesoporous carbon (MPC, CNovel) as support material for Pt catalysts in polymer electrolyte fuel cells and durability improvement of MPC by heat-treatment were investigated. Because the primary particle size of MPC is ~2 µm, MPC is bead-milled to about 800 nm. Surface area of MPC is 1338 m2 g-1, which is comparable to that of conventional porous carbon support KB-600JD 1350 m2 g-1, while internal surface area of MPC is 1253 m2 g-1, much larger than that of KB-600JD (716 m2 g-1). Mesopore size distribution of MPC is narrower than that of KB-600JD, with central mesopore size of 4 nm. 3D-TEM analysis shows that MPC has much higher density of interconnected mesopores (2-6 nm) than KB-600JD, and cross-sectional scanning electron microscopy observations indicate that macropores (> 50 nm) coexist in MPC. These pore structures contribute to higher cell voltage of Pt/MPC over Pt/KB-600JD in the entire current density region. MPC support is heat-treated at 1800-2400℃ in Ar to improve durability against high potentials (1.0-1.5 V vs. RHE). Durability of Pt/MPC is higher than that of Pt/KB-600JD and monotonically improves with increasing heat-treatment temperature. MPC support maintains high surface area of 800 m2 g-1 even after heat-treatment at 2200°C
Nicholas S. Sinclair et al 2025 J. Electrochem. Soc. 172 020525
Electrolytes based on deep eutectic solvents (DESs) coupled with redox active organic molecules have shown potential as a versatile and energy dense electrochemical energy storage system. However, progress in these systems has been held back by a lack of understanding of the irregular behavior displayed when redox active organic molecules are transitioned from other solvent systems. In this work, the hydrogen bonding characteristics of a series of redox organic molecules were investigated through infrared spectroscopy and molecular modeling. New understanding of these interactions was then used to explain their electrochemical behavior in a DES electrolyte. A model was used to predict the behavior of new derivatives towards the design of an optimized redox organic-DES system. Hydrogen bonding between the redox molecules and the solvent was found to significantly shift the potential of a redox reaction more positive when a hydrogen bond forms at the redox active site. It was predicted that functionalizing a molecule with electron withdrawing groups to lower the electron density of the redox active functional group lowers the strength of the hydrogen bond and thus alleviates the undesirable potential shift. This hypothesis was demonstrated by the addition of nitro groups to fluorenones.
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Zhi Zhou et al 2025 J. Electrochem. Soc. 172 020524
The desolvation of Li+ ion is generally considered to be the rate-determining step of Li+ insertion/extraction reactions at the negative and positive electrodes in the electrolyte solutions of Li-ion batteries (LIBs). However, specific factors that affect the charge-transfer kinetics at the electrode/electrolyte interface remain to be clearly understood. In this study, we investigated the interfacial charge-transfer reaction rate at LiMn2O4 thin-film electrodes in LiN(SO2CF3)2/monoglyme electrolytes. Our analysis revealed that the Li+ activity and electrolyte viscosity significantly affect the interfacial charge-transfer reaction rate. A higher Li-salt concentration enhances Li+ activity, accelerating the reaction rate. However, increasing the salt concentration beyond a certain level increases the electrolyte viscosity, which retards the interfacial reaction kinetics. A trade-off between these two factors results in the fastest reaction rate at an intermediate concentration (∼1.8 mol L−1). In the electrolytes with higher LiN(SO2CF3)2 concentrations, the chemical potential of Li+ increases, which facilitates the desolvation of Li+. However, the activation energy of the electrolyte viscosity increases with increasing salt concentration. Consequently, the activation energy of the interfacial charge-transfer reaction reached the minimum at approximately 1.8 mol L−1. These insights into the factors that affect the Li+ insertion reaction kinetics can help design optimal electrolytes for high-power LIBs.
Jay Deshmukh et al 2025 J. Electrochem. Soc. 172 020516
Prussian Blue Analogs are a promising class of positive electrode materials for sodium-ion batteries that can be synthesized at low temperatures using only Earth-abundant elements like sodium, iron, and manganese. Their open framework structure allows them to sustain high current densities but also makes them prone to absorption of moisture. We improve the specific capacity of sodium manganese hexacyanoferrate (MnHCF) by optimizing synthesis and processing conditions, enabling a material-level energy density of 562 Wh kg−1, which is on par with lithium iron phosphate. We remove interstitial water from these materials by rigorous drying. We also demonstrate a factor two improvement in cycling life of MnHCF by substituting only 3 at. % Ni for Mn and leaving some vacancies, which leads to 80% capacity retention after 3,500 h (∼5 months) of cycling in Na half cells at 0.2 C between 2.0 and 4.1 V and an ability to retain >85% capacity at a high current density of 10 C.
Črt Saksida et al 2025 J. Electrochem. Soc. 172 022505
This study explores Cu electrodeposition from a near-neutral sulphate bath onto Nd-Fe-B bulk and powder electrodes. The former served for the preliminary electrochemical tests, while the latter was used for Cu coating of the corrosion-sensitive powdery raw material. Cyclic voltammetry established the potential intervals for Cu deposition (at least −0.1 V and below) and the Nd-Fe-B oxidation (above −0.5 V). Cu electrodepositions were performed on both electrodes in potentiostatic mode for 30 s. Scanning electron microscopy/energy-dispersive spectroscopy showed that Cu deposited at high overpotentials (−1.05 and −0.5 V) had a dendritic structure mainly due to mass transport limitations. A chronoamperometric study on Nd2Fe14B powder electrodes at −0.25 V resulted in a positive current, indicating the Nd-Fe-B oxidation dominance. At −0.5 V, the current remained negative, but showed diffusion limitations. The latter was improved by using ultrasonic agitation, which resulted in a higher total negative charge and more uniform Cu deposits on Nd2Fe14B grains. Cu-coated Nd₂Fe₁₄B grains showed a mass magnetization decrease from 137 to 127 emu g−1, corresponding to a ∼9% Cu mass increase determined via gravimetry. The study demonstrates successful Cu electrochemical deposition with no magnetization loss beyond the paramagnetic Cu phase, paving the way for grain-boundary engineering of novel Nd-Fe-B magnets.
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Highlights
Copper was electrodeposited on Nd2Fe14B magnetic grains from aqueous solution.
Deposition at −0.5 V vs Ag/AgCl limits Nd2Fe14B oxidation and dendritic Cu growth.
Ultrasonic agitation aids mass transport, improving uniformity of copper coatings.
This opens possibilities for grain boundary engineering of novel Nd-Fe-B magnets.
Henrik Grimler et al 2025 J. Electrochem. Soc. 172 024507
Water is a key factor in anion-exchange membrane fuel cells, since it is both a product and a reactant, and humidifies the membrane and the ionomer phase. To optimize the operation conditions preventing cathode drying and anode flooding, better knowledge on the water transport is needed. In this work, the water transport across an AemionTM membrane is quantified for different applied water partial pressure differences and current densities. Two membrane thicknesses, 25 and 50 μm, are studied, as well as two gas diffusion layers (GDLs) of different hydrophobicity: the hydrophobic Sigracet 25BC treated with polytetrafluoroethylene (PTFE), and Freudenberg H23C2 being hydrophilic as it is not treated with PTFE. The measurements show that having a hydrophilic GDL on both electrodes results in poor electrochemical performance, and restricted water transport. Although the highest water molar flux was observed for hydrophilic GDL on cathode and hydrophobic GDL on anode, the best electrochemical performance was observed for the opposite combination. A water transport model considering absorption/desorption resistance, electroosmotic drag and diffusion was deployed. The best fit of the model to the experimental data was obtained with a water drag coefficient of 2, and almost about 30% difference in absorption/desorption coefficient due to different GDLs.
Baptiste Py and Francesco Ciucci 2025 J. Electrochem. Soc. 172 026504
Electrochemical impedance spectroscopy (EIS) is a powerful analytical technique offering broad frequency range and straightforward implementation. However, low-frequency measurements are constrained by lengthy acquisition times and potential disruption of steady-state conditions. While the distribution of relaxation times (DRT) can accelerate impedance acquisition and interpret EIS data, current approaches are limited to pulse signals and their linear combinations. Herein, we present a novel, fast Fourier transform-based DRT formulation for rapid EIS acquisition with arbitrary signals and DRT deconvolution. Our approach demonstrates computational efficiency and improved DRT recovery, advancing opportunities for fast, efficient EIS characterization.
Kyra Glassey et al 2025 J. Electrochem. Soc. 172 020523
Solid electrolytes are critical for structural batteries, combining energy storage with structural strength for applications like electric vehicles and aerospace. However, achieving high ionic conductivity remains challenging, compounded by a lack of standardized testing methodologies. This study examines the impact of experimental setups and data interpretation methods on the measured ionic conductivities of solid polymer electrolytes (SPEs). SPEs were prepared using a polymer-induced phase separation process, resulting in a bi-continuous microstructure for improved ionic transport. Eight experimental rigs were evaluated, including two- and four-electrode setups with materials like stainless steel, copper, and aluminum. Ionic conductivity was assessed using electrochemical impedance spectroscopy, with analysis methods comparing cross-sectional and surface-area-based approaches. Results showed that the four-electrode stainless steel setup yielded the highest ionic conductivity using the cross-sectional method. However, surface-area-based methods provided more consistent results across rigs. Copper setups produced lower conductivities but exhibited less data variability, indicating their potential for reproducible measurements. These findings highlight the critical influence of experimental design on conductivity measurements and emphasize the need for standardized testing protocols. Advancing reliable characterization methods will support the development of high-performance solid electrolytes for multifunctional energy storage applications.
Tianyi Han et al 2025 J. Electrochem. Soc.
Industrial by-product hydrogen and reformate hydrogen from ammonia are possible fuels for proton exchange membrane fuel cells (PEMFCs) which may have ammonia impurities that damage the performance. This study investigates the influence of ammonia impurities in anode fuel on the performance of PEMFCs. Comprehensive electrochemical characterizations were employed to analyze the effects of varying ammonia concentrations and relative humidity (RH) levels. The results demonstrate that ammonia impurities significantly increase electrode activation overpotentials and proton transfer resistance in the cathode catalyst layer and membrane, with more pronounced effects under low RH conditions. Ammonia adsorption on platinum catalysts reduces the electrochemical active surface area and impedes the oxygen reduction reaction, leading to increased activation losses. Additionally, ammonia binding with membrane sulfonate groups elevates proton transfer resistance. These findings underscore the critical need to control ammonia impurities in anode fuel to maintain optimal PEMFC performance.