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.
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.
Open all abstracts, in this tab
Manuel Ank et al 2023 J. Electrochem. Soc. 170 120536
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.
Jorn M. Reniers et al 2019 J. Electrochem. Soc. 166 A3189
The maximum energy that lithium-ion batteries can store decreases as they are used because of various irreversible degradation mechanisms. Many models of degradation have been proposed in the literature, sometimes with a small experimental data set for validation. However, a comprehensive comparison between different model predictions is lacking, making it difficult to select modelling approaches which can explain the degradation trends actually observed from data. Here, various degradation models from literature are implemented within a single particle model framework and their behavior is compared. It is shown that many different models can be fitted to a small experimental data set. The interactions between different models are simulated, showing how some of the models accelerate degradation in other models, altering the overall degradation trend. The effects of operating conditions on the various degradation models is simulated. This identifies which models are enhanced by which operating conditions and might therefore explain specific degradation trends observed in data. Finally, it is shown how a combination of different models is needed to capture different degradation trends observed in a large experimental data set. Vice versa, only a large data set enables to properly select the models which best explain the observed degradation.
Weilong Ai et al 2020 J. Electrochem. Soc. 167 013512
Whilst extensive research has been conducted on the effects of temperature in lithium-ion batteries, mechanical effects have not received as much attention despite their importance. In this work, the stress response in electrode particles is investigated through a pseudo-2D model with mechanically coupled diffusion physics. This model can predict the voltage, temperature and thickness change for a lithium cobalt oxide-graphite pouch cell agreeing well with experimental results. Simulations show that the stress level is overestimated by up to 50% using the standard pseudo-2D model (without stress enhanced diffusion), and stresses can accelerate the diffusion in solid phases and increase the discharge cell capacity by 5.4%. The evolution of stresses inside electrode particles and the stress inhomogeneity through the battery electrode have been illustrated. The stress level is determined by the gradients of lithium concentration, and large stresses are generated at the electrode-separator interface when high C-rates are applied, e.g. fast charging. The results can explain the experimental results of particle fragmentation close to the separator and provide novel insights to understand the local aging behaviors of battery cells and to inform improved battery control algorithms for longer lifetimes.
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.
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.
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.
John G. Petrovick et al 2023 J. Electrochem. Soc. 170 114519
Anion-exchange membranes (AEMs) are a possible replacement for perfluorosulfonic-acid membranes in energy-conversion devices, primarily due to the hydroxide mobile ion allowing the devices to operate in alkaline conditions with less expensive electrocatalysts. However, the transport properties of AEMs remain understudied, especially electro-osmosis. In this work, an electrochemical technique, where the open-circuit voltage is measured between two ends of a membrane maintained at different relative humidities, is used to determine the water transport number of various ionomers, including Versogen and Sustainion AEMs and Nafion cation-exchange membrane (CEM), as a function of water content and temperature. In addition, the CEMs and AEMs are examined in differing single-ion forms, specifically proton and sodium (CEM) and hydroxide and carbonate (AEM). Carbonate-form AEMs have the highest transport number (∼11), followed by sodium-form CEMs (∼8), hydroxide-form AEMs (∼6), and proton-form CEMs (∼3). Finally, a multicomponent transport model based on the Stefan-Maxwell-Onsager framework of binary interactions is used to develop a link between water transport number and water-transport properties, extracting a range for the unmeasured membrane water permeability of Versogen as a function of water content.
Sarah F. Zaccarine et al 2022 J. Electrochem. Soc. 169 064502
Polymer electrolyte membrane water electrolyzers (PEMWEs) are devices of paramount importance, enabling the large-scale storage of hydrogen from intermittent renewable energy sources such as wind and solar. But a transition towards lower noble metal catalyst loadings and intermittent operation is needed for the widespread utilization of this technology. Although kinetic losses tend to dominate in membrane electrode assembly (MEA) results, it has been suggested that morphological changes and interfaces between the catalyst, ionomer, and membrane will also contribute to overall degradation. Moreover, the combination of degradation to the catalyst layer (CL) constituents will further lead to structural changes that have not been widely explored. The multitude and complexity of degradation mechanisms, which likely occur simultaneously, require a characterization approach that can explore surfaces and interfaces at a range of length-scales to probe chemical, morphological, and structural changes of constituents within the catalyst later. This paper presents a comprehensive characterization approach that features scanning electron microscopy (SEM), scanning transmission electron microscopy with energy-dispersive X-Ray spectroscopy (STEM/EDS), X-Ray photoelectron spectroscopy (XPS), X-Ray absorption spectroscopy (XAS), and transmission X-Ray microscopy (TXM) with X-Ray absorption near-edge structure (XANES) chemical mapping to study degradation of the catalyst layer with a focus on MEAs after intermittent and steady-state operation. Catalyst changes including dissolution, oxidation, and agglomeration were observed, as well as redistribution and dissociation of the ionomer. These smaller-scale changes were found to have a large influence on overall stability of the electrodes: they caused the formation of voids and segregation of constituents within regions of the film. Delamination and collapse of the overall catalyst layer were observed in some instances. Greater changes were observed after an extended 2 V hold compared to IV cycling, but similar degradation mechanisms were detected, which suggests the larger issues would likely also be experienced during intermittent PEMWE operation. These findings would not be possible without such a systematic, multi-scale, multi-technique characterization approach, which highlights the critical importance of detailed analysis of catalyst layer degradation to propose mitigation strategies and improve long-term PEM water electrolyzer performance.
Chang Liu et al 2023 J. Electrochem. Soc. 170 034508
The porous transport layer (PTL)/catalyst layer (CL) interface plays a crucial role in the achievement of high performance and efficiency in polymer electrolyte membrane water electrolyzers (PEMWEs). This study investigated the effects of the PTL/CL interface on the degradation of membrane electrode assemblies (MEAs) during a 4000 h test, comparing the MEAs assembled with uncoated and Ir-coated Ti PTLs. Our results show that compared to an uncoated PTL/CL interface, an optimized interface formed when using a platinum group metal (PGM) coating, i.e., an iridium layer at the PTL/CL interface, and reduced the degradation of the MEA. The agglomeration and formation of voids and cracks could be found for both MEAs after the long-term test, but the incorporation of an Ir coating on the PTL did not affect the morphology change or oxidation of IrOx in the catalyst layer. In addition, our studies suggest that the ionomer loss and restructuring of the anodic MEA can also be reduced by Ir coating of the PTL/CL interface. Optimization of the PTL/CL interface improves the performance and durability of a PEMWE.
Open all abstracts, in this tab
Lena V. Bühre et al 2024 J. Electrochem. Soc. 171 054519
The commercialization of proton exchange membrane water electrolysis cells (PEMWEs), which are essential for a greener and more sustainable future, is hindered by the high costs of noble metal catalysts, as well as the degradation of the catalysts and membranes. Examining the electrodes' characteristics with reference electrodes (REs) yields insights into their individual performance and can, e.g., help assess new catalyst layer designs, their interplay with the adjacent porous transport layer, or understand the complex and multi-faceted degradation mechanisms. This review provides an overview of previous approaches and the evolution of RE designs in PEMWE. By discussing the strengths and limitations of different RE setups, readers are enabled to make more informed decisions about their experiments' design and choose the best RE setup for their specific research question.
Mingquan Lu et al 2024 J. Electrochem. Soc. 171 051506
AISI 1018 carbon steel exhibits intergranular attack in molten aluminum chloride. To explore grain boundary corrosion initiation and propagation, tests have been conducted on several iron-based alloys, heat treated to recrystallization temperature, and using molten aluminum chloride and its mixture with other molten chlorides environments. Pure iron, A106, and AISI 1018 carbon steel have been exposed to both pure aluminum chloride and ferric chloroaluminate melt in both their recrystallized and as-received, cold-worked conditions. Intergranular corrosion is observed in both 1018 and A106 carbon steels in all the salts whereas pure iron only shows pitting. Materials processing has varying effects on the corrosion depths of 1018 and A106 carbon steels. The grain boundary microchemistry of 1018 carbon steel is examined with in situ fracture Auger spectroscopy where molybdenum and carbon segregation are found, and a mechanism is proposed to explain the present corrosion phenomenon.
A. M. AbdelAty et al 2024 J. Electrochem. Soc. 171 050553
The precise identification of electrical model parameters of Li-Ion batteries is essential for efficient usage and better prediction of the battery performance. In this work, the model identification performance of two metaheuristic optimization algorithms is compared. The algorithms in comparison are the Marine Predator Algorithm (MPA) and the Partial Reinforcement Optimizer (PRO) to find the optimal model parameter values. Three fractional-order (FO) electrical equivalent circuit models (ECMs) of Li-Ion batteries with different levels of complexity are used to fit the electrochemical impedance spectroscopy (EIS) data operating under different states of charge (SoC) and different operating temperatures. It is found that there is a tradeoff between ECM complexity, identification accuracy, and precision.
Lena V. Bühre et al 2024 J. Electrochem. Soc. 171 054518
We investigated a three electrode setup utilized in a temperature variation study to extract the activation energy for the half-cell reactions in PEM water electrolysis and the contributions of electronic resistances to ohmic resistance. The reference electrode configuration used in this investigation is an improved version of a setup previously introduced by our group. Enhancements have been made to minimize the influence of the reference electrode and improve the accuracy of electrochemical impedance spectroscopy.
D. Esau et al 2024 J. Electrochem. Soc. 171 054522
Modelling of the co-electrolysis process requires understanding of the underlying reaction pathways under H2/H2O/CO/CO2-atmospheres. These include the electrochemical steam reduction/hydrogen oxidation, the electrochemical CO2 reduction/CO oxidation and their coupling via the catalytic (reverse) water gas shift reaction ((R)WGS). The assumption of a very fast RWGS and therefore neglectable electrochemical CO2 conversion is commonly used to model the co-electrolysis process. In contrast, previous studies on Ni/GDC fuel electrodes suggest that the electrochemical conversion of CO/CO2 can be present in H2/H2O/CO/CO2-atmospheres. To deconvolute surface-related and non-surface-related processes in the impedance response we present results from a complex variation of operating parameters for process identification by the use of electrochemical impedance spectroscopy and the subsequent impedance analysis by the distribution of relaxation times. A physically meaningful equivalent circuit model, based on a single channel transmission line, is then derived. The model enables quantification of the surface reaction resistance under varied C/H-ratios. From a kinetic analysis it is shown that the electrochemical H2/H2O conversion is dominant for 50% and electrochemical CO/CO2-conversion onsets from ≥ 60%.
Open all abstracts, in this tab
Lena V. Bühre et al 2024 J. Electrochem. Soc. 171 054519
The commercialization of proton exchange membrane water electrolysis cells (PEMWEs), which are essential for a greener and more sustainable future, is hindered by the high costs of noble metal catalysts, as well as the degradation of the catalysts and membranes. Examining the electrodes' characteristics with reference electrodes (REs) yields insights into their individual performance and can, e.g., help assess new catalyst layer designs, their interplay with the adjacent porous transport layer, or understand the complex and multi-faceted degradation mechanisms. This review provides an overview of previous approaches and the evolution of RE designs in PEMWE. By discussing the strengths and limitations of different RE setups, readers are enabled to make more informed decisions about their experiments' design and choose the best RE setup for their specific research question.
Kokilavani R et al 2024 J. Electrochem. Soc. 171 057516
Immunosensors have emerged as vital tools in cancer diagnostics, providing simplified and rapid detection of biomarkers that are necessary for timely diagnosis. The objective of using an electrochemical immunosensor is to detect cancers at early stages, so that obtained biological information can be analyzed using artificial intelligence (AI) for deciding an appropriate treatment, avoiding false diagnosis, and preventing patient fatalities. The focus of this article is on four major reproductive cancers—breast, ovarian, cervical, and prostate cancers. Specifically, it explores the identification and optimization of biomarkers crucial for the precise detection of these cancers. Examining a decade of research, the review delves into nanotechnology-assisted electrochemical immunosensors (affinity biosensors), outlining advancements and emphasizing their potential in reproductive cancer diagnostics. Furthermore, the review contemplates avenues for enhancing sensor characteristics to pave the way for their application in field diagnosis, with a forward-looking perspective on AI-assisted diagnostics for the next generation of personalized healthcare. In navigating the landscape of reproductive cancer diagnostics, the integration of advanced technologies promises to transform our approach, offering improved accuracy and outcomes for patients.
Endao Zhang and Wei Song 2024 J. Electrochem. Soc. 171 052503
Hydrogen is a prime candidate for replacing fossil fuels. Electrolyzing water to produce hydrogen stands out as a particularly clean method, garnering significant attention from researchers in recent years. Among the various techniques for electrolyzing water to produce hydrogen, alkaline electrolysis holds the most promise for large-scale industrialization. The key to advancing this technology lies in the development of durable and cost-effective electrocatalysts for the hydrogen evolution reaction (HER). Self-supporting electrode is an electrode structure in which a catalyst layer is formed directly on a substrate (such as carbon cloth, nickel foam, stainless steel, etc) without using a binder and with good structural stability. In contrast to traditional nanocatalysts, self-supporting electrocatalysts offer significant advantages, including reduced resistance, enhanced stability, and prolonged usability under high currents. This paper reviews recent advancements in HER electrochemical catalysts for alkaline water electrolysis, focusing on the utilization of hydrogen-evolving catalysts such as metal sulfides, phosphides, selenides, oxides, and hydroxides. With self-supported electrocatalysts as the focal point, the paper delves into progress made in their preparation techniques, structural design, understanding of reaction mechanisms, and strategies for performance enhancement. Ultimately, the future development direction of promoting hydrogen evolution by self-supported electrocatalysts in alkaline water electrolysis is summarized.
Vinh Van Tran et al 2024 J. Electrochem. Soc. 171 056509
The quest for economical and sustainable electrocatalysts to facilitate the hydrogen evolution reaction (HER) is paramount in addressing the pressing challenges associated with carbon dioxide emissions. Molybdenum carbide-based nanomaterials have emerged as highly promising electrocatalysts for HER due to their Pt-like catalytic proficiency, exceptional stability, and the versatility of their crystal phases. Within this comprehensive review, we explore the diverse methodologies for synthesizing molybdenum carbides, including solid-gas, solid-solid, and solid-liquid phase reactions. In addition, a thorough elucidation of the hydrogen generation process through water electrolysis is provided. Furthermore, a spectrum of innovative strategies aimed at augmenting the performance of molybdenum carbides in the HER milieu is introduced, encompassing cutting-edge techniques such as phase-transition engineering, the construction of heterostructures, hetero-atom doping, the integration of hybrid structures with carbon materials, defect engineering, and meticulous surface modification. The review culminates by underscoring the current challenges and the promising prospects in the advancement of electrocatalysts for hydrogen production, with a dedicated focus on molybdenum carbide-based catalysts.
Highlights
Outstanding properties of molybdenum carbides were presented.
Various approaches for the fabrication of molybdenum carbides.
Different strategies on molybdenum carbides-based electrocatalyst for water electrolysis were discussed.
Current difficulties and possible solutions on molybdenum carbides-based electrocatalyst for water electrolysis have been introduced.
Mingyang Cao and Mingqiang Li 2024 J. Electrochem. Soc. 171 050543
Zinc ion batteries (ZIBs), as an emerging low-cost and high-safety energy storge option, have the advantages of high energy and low reduction potential. With the development of high-performance cathode materials and electrolyte systems, as well as the deepening of mechanism research, the electrochemical performance of ZIBs has been greatly improved. However, the shortcomings of various materials have hindered the development of zinc ion batteries. With the deepening of research and the deepening of understanding of various materials, a brief outlook was given on the future development of electrode materials in aqueous zinc ion batteries.
Highlights
Comparing the performance of zinc ion batteries that extensively use various electrode materials.
Propose that composite electrode can improve the shortcomings of electrode materials to a certain extent and optimize battery performance.
Propose to introduce other ions into zinc-based double-ion batteries to improve battery performance.
Open all abstracts, in this tab
S. Friedrich et al 2024 J. Electrochem. Soc. 171 050540
The impact of mechanical pressure on electrode stability in full-cells comprising microscale silicon-dominant anodes and NCA cathodes was investigated. We applied different mechanical pressures using spring-compressed T-cells with metallic lithium reference electrodes enabling us to analyze the electrode-specific characteristics. Our investigation covers a wide pressure range from 0.02 MPa (low pressure - LP) to 2.00 MPa (ultra high pressure - UHP) to determine the optimal pressure for cyclic lifetime and energy density. We introduce an experimental methodology considering single-component compression to adjust the cell setup precisely. We characterize the cells using impedance spectroscopy and age them at C/2. In the post-mortem analysis, cross-sections of the aged anodes are measured with scanning electron microscopy. The images are analyzed with regard to electrochemical milling, thickness gain, and porosity decrease by comparing them to the pristine state. The results indicate that cycling at UHP has a detrimental effect on cycle life, being almost two-fold shorter when compared to cycling at normal pressure (NP, 0.20 MPa). Scanning electron microscopy showed a dependency of the thickness and the porosity of the aged silicon anodes on the applied pressure, with coating thickness increasing and porosity decreasing for all pressure settings, and a correlation between thickness and porosity.
Hong Zhang et al 2024 J. Electrochem. Soc. 171 047510
Ordered Pt/SnO2 composite porous thin films were prepared for fabrication of planar mixed-potential hydrogen sensors. Characterization of the Pt/SnO2 films revealed that Pt elements were primarily loaded in Pt° form on the SnO2 film surface and did not significantly change the morphology of the film electrodes. The potentiometric response of Pt/SnO2 thin films to hydrogen varied with the Pt loading contents. Compared to the pristine SnO2 film, the 1 at% and 2 at% Pt-loaded SnO2 composite films exhibited 1.6 and 2.0 times higher potentiometric response to 300 ppm hydrogen at 500 °C, with a similar response time of 6–10.5 s. By assembling an array of sensors composed of SnO2 films loaded with 1 at% and 2 at% Pt, and using principal component analysis, discrimination of hydrogen and four interfering gases (ammonia, carbon monoxide, nitrogen dioxide, and propane) in the concentration range of 100–300 ppm was achieved. The sensing behaviors of the Pt/SnO2 composite thin films were discussed in relation to the competitive promotion effects for the heterogeneous and electrochemical catalytic activities by Pt loading.
Highlights
Potentiometric hydrogen sensors based on Pt/SnO2 thin films were fabricated.
Hydrogen sensing response was enhanced by loading 1 at% and 2 at% Pt.
The sensing behavior was discussed by the Pt competitive promotion effects.
Discrimination of hydrogen and four interfering gases was achieved.
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
Yuefan Ji and Daniel T. Schwartz 2023 J. Electrochem. Soc. 170 123511
Analytical theory for second harmonic nonlinear electrochemical impedance spectroscopy (2nd-NLEIS) of planar and porous electrodes is developed for interfaces governed by Butler-Volmer kinetics, a Helmholtz (mainly) or Gouy-Chapman (introduced) double layer, and transport by ion migration and diffusion. A continuum of analytical EIS and 2nd-NLEIS models is presented, from nonlinear Randles circuits with or without diffusion impedances to nonlinear macrohomogeneous porous electrode theory that is shown to be analogous to a nonlinear transmission-line model. EIS and 2nd-NLEIS for planar electrodes share classic charge transfer RC and diffusion time-scales, whereas porous electrode EIS and 2nd-NLEIS share three characteristic time constants. In both cases, the magnitude of 2nd-NLEIS is proportional to nonlinear charge transfer asymmetry and thermodynamic curvature parameters. The phase behavior of 2nd-NLEIS is more complex and model-sensitive than in EIS, with half-cell NLEIS spectra potentially traversing all four quadrants of a Nyquist plot. We explore the power of simultaneously analyzing the linear EIS and 2nd-NLEIS spectra for two-electrode configurations, where the full-cell linear EIS signal arises from the sum of the half-cell spectra, while the 2nd-NLEIS signal arises from their difference.
Open all abstracts, in this tab
Yang et al
As an indispensable component of lithium-ion batteries (LIBs), the application of porous copper (Cu) foil current collector is an effective method to improve the performance and energy density of LIBs. In this work, a porous Cu (PCu) foil was fabricated by acid washing the Cu-Fe3O4 foil prepared by the electro-codeposition in a stirred CuSO4 solution containing the magnetic Fe3O4 nanoparticles. The effect of the stirring speed on the properties of PCu foils and the battery performance of PCu foil as current collectors were investigated. The surface roughness of the PCu foil increases, while its volume density decreases as the stirring speed rises. The volume density of PCu foil (6.63 g cm-3) prepared at 400 rpm (PCu400) is reduced by 22.4% than that of the commercial Cu foil (8.55 g cm-3). The specific capacity (241.2 mAh g-1) of the cell with PCu400 current collector is 31.3% higher than that of the cell with commercial Cu current collector (183.7 mAh g-1) after 300 charge-discharge cycles at 2 C. The electro-codeposition of porous Cu foil current collectors offers a promising method for high-performance lightweight LIBs.
Liu et al
Layered transition metal oxides are one of the most promising positive electrode materials for sodium ion batteries. However, the instability of the structure and poor rate performance during the charging-discharging process limit its application. Herein, a high-temperature solid-state reaction and liquid phase coating method is developed to synthesize the P2-type cathode of Na0.85Li0.12Ni0.22Mn0.66O2-1%wt TiO2 (denoted as NLNMO-1%wt TiO2). The layered oxide cathode with TiO2-coating exhibits a superior rate capability, delivers a high reversible capacity of 111.4 mAh g-1 at 1 C with a capacity retention of 94.5 % after 100 cycles, and maintains a capacity of 87.1 mAh g-1 at 5 C with a capacity retention of 81.8 % after 400 cycles. This new strategy reduces the relative content of Mn3+, which suppresses the Jahn-Teller effect and enhances the structural stability. Moreover, it forms a stable CEI film, which reduces the side reactions between cathode surface and the electrolyte, suppressing the pulverization of the electrode, as confirmed by scanning electron microscopy and high-resolution transmission electron microscopy. The results of this work indicate that the composite cathode of NLNMO-1%wt TiO2 has a long cycle life and excellent rate performance for rechargeable sodium-ion batteries.
Changyu et al
The Lithium-Sulfur (Li-S) battery emerges as a candidate in the next-generation batteries, attributed to its superior energy density and cost-effectiveness. Despite these advantages, the longevity of Li-S batteries remains a complex challenge. The shuttle effect has been identified as a principal factor contributing to degradation, prompting extensive research aimed at mitigating its impact. Recent studies, however, have unveiled that the presence of Li2S exerts a significant influence on the kinetic and stability of the cell. Although lower cut-off voltage controls the Li2S formation directly, its relation has not been investigated so far. In this study, we regulated the discharge voltage and revealed the relation between lower cut-off voltage and electrochemical stability. Low lower cut-off voltage can maximize the Li2S formation and first discharge capacity, but it retards the Li2S transformation to sulfur. It is confirmed by high overpotential and low charge capacity. Furthermore, repeated cycles at deep discharge exhibits severe capacity loss and deteriorated coulombic efficiency. Whereas, high lower cut-off voltage cell exhibits enhanced capacity retention with low overpotential due to restriction of Li2S formation. Thus, this study provides insight control of Li2S formation is critical to stabilize the electrochemical reaction and key to enhance the lifespan of Li-S batteries.
Triolo et al
High-entropy oxides with spinel structure (SHEOs) are promising anode materials for next-generation lithium-ion batteries (LIBs). In this work, electrospun (Mn,Fe,Co,Ni,Zn) SHEO nanofibers produced under different conditions are evaluated as anode materials in LIBs and thoroughly characterised by a combination of analytical techniques. The variation of metal load (19.23 or 38.46 wt% relative to the polymer) in the precursor solution and of calcination conditions (700°C/0.5 h, or 700°C/2 h followed by 900°C/2 h) affects the morphology, microstructure, crystalline phase, and surface composition of the pristine SHEO nanofibers and the resulting electrochemical performance, whereas mechanism of Li storage does not substantially change. Causes of long-term (650 cycles) capacity fading are elucidated via ex situ synchrotron X-ray absorption spectroscopy. The results evidence that the larger amounts of Fe, Co, and Ni cations irreversibly reduced to the metallic form during cycling are responsible for faster capacity fading in nanofibers calcined under milder conditions. The microstructure of the active material plays a key role. Nanofibers composed by larger and better-crystallized grains, where a stable solid/electrolyte interphase forms, exhibit superior long-term stability (453 mAh g1 after 550 cycles at 0.5 A g1) and rate-capability (210 mAh g1 at 2 A g1).
Azuma et al
Metal-assisted etching (metal-assisted chemical etching) is an efficient method to fabricate porous silicon (Si). When using platinum (Pt) particles as metal catalysts in metal-assisted etching, a composite porous structure of straight macropores formed beneath the Pt particles and a mesoporous layer formed on the entire surface of Si can be fabricated. The formation mechanism of the composite structure is still open to discussion. We previously demonstrated that the ratio of mesoporous layer thickness to macropore depth showed a large value (approximately 1.1) in the case of highly-doped p-Si. In this study, we investigated the composite structure formation by using p-Si substrates with different doping densities and etching solutions with different concentrations of hydrogen peroxide (H2O2). There was not significant difference in the structures formed on low- and moderately-doped Si, despite the large difference in doping density. The ratio of mesoporous layer thickness to macropore depth increased within the range approximately from 0.1 to 0.4 with increasing the H2O2 concentration in the case of low- and moderately-doped Si, but it did not change in the case of highly-doped Si. We discussed the observation results based on the spatial distribution of hole consumption and the band structures at Pt/Si and Si/electrolyte interfaces.
Trending on Altmetric
Open all abstracts, in this tab
Lena V. Bühre et al 2024 J. Electrochem. Soc. 171 054519
The commercialization of proton exchange membrane water electrolysis cells (PEMWEs), which are essential for a greener and more sustainable future, is hindered by the high costs of noble metal catalysts, as well as the degradation of the catalysts and membranes. Examining the electrodes’ characteristics with reference electrodes (REs) yields insights into their individual performance and can, e.g., help assess new catalyst layer designs, their interplay with the adjacent porous transport layer, or understand the complex and multi-faceted degradation mechanisms. This review provides an overview of previous approaches and the evolution of RE designs in PEMWE. By discussing the strengths and limitations of different RE setups, readers are enabled to make more informed decisions about their experiments’ design and choose the best RE setup for their specific research question.
Lena V. Bühre et al 2024 J. Electrochem. Soc. 171 054518
We investigated a three electrode setup utilized in a temperature variation study to extract the activation energy for the half-cell reactions in PEM water electrolysis and the contributions of electronic resistances to ohmic resistance. The reference electrode configuration used in this investigation is an improved version of a setup previously introduced by our group. Enhancements have been made to minimize the influence of the reference electrode and improve the accuracy of electrochemical impedance spectroscopy.
D. Esau et al 2024 J. Electrochem. Soc. 171 054522
Modelling of the co-electrolysis process requires understanding of the underlying reaction pathways under H2/H2O/CO/CO2-atmospheres. These include the electrochemical steam reduction/hydrogen oxidation, the electrochemical CO2 reduction/CO oxidation and their coupling via the catalytic (reverse) water gas shift reaction ((R)WGS). The assumption of a very fast RWGS and therefore neglectable electrochemical CO2 conversion is commonly used to model the co-electrolysis process. In contrast, previous studies on Ni/GDC fuel electrodes suggest that the electrochemical conversion of CO/CO2 can be present in H2/H2O/CO/CO2-atmospheres. To deconvolute surface-related and non-surface-related processes in the impedance response we present results from a complex variation of operating parameters for process identification by the use of electrochemical impedance spectroscopy and the subsequent impedance analysis by the distribution of relaxation times. A physically meaningful equivalent circuit model, based on a single channel transmission line, is then derived. The model enables quantification of the surface reaction resistance under varied C/H-ratios. From a kinetic analysis it is shown that the electrochemical H2/H2O conversion is dominant for 50% and electrochemical CO/CO2-conversion onsets from ≥ 60%.
Yeo Changyu and Minkyung Kim 2024 J. Electrochem. Soc.
The Lithium-Sulfur (Li-S) battery emerges as a candidate in the next-generation batteries, attributed to its superior energy density and cost-effectiveness. Despite these advantages, the longevity of Li-S batteries remains a complex challenge. The shuttle effect has been identified as a principal factor contributing to degradation, prompting extensive research aimed at mitigating its impact. Recent studies, however, have unveiled that the presence of Li2S exerts a significant influence on the kinetic and stability of the cell. Although lower cut-off voltage controls the Li2S formation directly, its relation has not been investigated so far. In this study, we regulated the discharge voltage and revealed the relation between lower cut-off voltage and electrochemical stability. Low lower cut-off voltage can maximize the Li2S formation and first discharge capacity, but it retards the Li2S transformation to sulfur. It is confirmed by high overpotential and low charge capacity. Furthermore, repeated cycles at deep discharge exhibits severe capacity loss and deteriorated coulombic efficiency. Whereas, high lower cut-off voltage cell exhibits enhanced capacity retention with low overpotential due to restriction of Li2S formation. Thus, this study provides insight control of Li2S formation is critical to stabilize the electrochemical reaction and key to enhance the lifespan of Li-S batteries.
Claudia Triolo et al 2024 J. Electrochem. Soc.
High-entropy oxides with spinel structure (SHEOs) are promising anode materials for next-generation lithium-ion batteries (LIBs). In this work, electrospun (Mn,Fe,Co,Ni,Zn) SHEO nanofibers produced under different conditions are evaluated as anode materials in LIBs and thoroughly characterised by a combination of analytical techniques. The variation of metal load (19.23 or 38.46 wt% relative to the polymer) in the precursor solution and of calcination conditions (700°C/0.5 h, or 700°C/2 h followed by 900°C/2 h) affects the morphology, microstructure, crystalline phase, and surface composition of the pristine SHEO nanofibers and the resulting electrochemical performance, whereas mechanism of Li storage does not substantially change. Causes of long-term (650 cycles) capacity fading are elucidated via ex situ synchrotron X-ray absorption spectroscopy. The results evidence that the larger amounts of Fe, Co, and Ni cations irreversibly reduced to the metallic form during cycling are responsible for faster capacity fading in nanofibers calcined under milder conditions. The microstructure of the active material plays a key role. Nanofibers composed by larger and better-crystallized grains, where a stable solid/electrolyte interphase forms, exhibit superior long-term stability (453 mAh g1 after 550 cycles at 0.5 A g1) and rate-capability (210 mAh g1 at 2 A g1).
Kyohei Azuma et al 2024 J. Electrochem. Soc.
Metal-assisted etching (metal-assisted chemical etching) is an efficient method to fabricate porous silicon (Si). When using platinum (Pt) particles as metal catalysts in metal-assisted etching, a composite porous structure of straight macropores formed beneath the Pt particles and a mesoporous layer formed on the entire surface of Si can be fabricated. The formation mechanism of the composite structure is still open to discussion. We previously demonstrated that the ratio of mesoporous layer thickness to macropore depth showed a large value (approximately 1.1) in the case of highly-doped p-Si. In this study, we investigated the composite structure formation by using p-Si substrates with different doping densities and etching solutions with different concentrations of hydrogen peroxide (H2O2). There was not significant difference in the structures formed on low- and moderately-doped Si, despite the large difference in doping density. The ratio of mesoporous layer thickness to macropore depth increased within the range approximately from 0.1 to 0.4 with increasing the H2O2 concentration in the case of low- and moderately-doped Si, but it did not change in the case of highly-doped Si. We discussed the observation results based on the spatial distribution of hole consumption and the band structures at Pt/Si and Si/electrolyte interfaces.
Leila Saberi et al 2024 J. Electrochem. Soc. 171 051505
This study investigates the impact of process-induced defects such as gas pores, lack of fusions, and surface roughness on corrosion behavior of stainless steel 304L (SS304L) fabricated by laser powder bed fusion additive manufacturing. Specimens are printed with optimized process parameters but selected from different locations on the build plate. Parallel and perpendicular surfaces to the build direction are investigated and compared with corrosion properties of wrought SS304L in 5 wt% NaCl. The results reveal significant difference in corrosion behavior among specimens due to variations in their defect features. Pitting potential, pit initiation, and growth rates are found to be influenced by specimen location on the build plate. The specimen located in downstream of the shielding gas flow shows the least corrosion resistance. While no clear trends are observed between some corrosion properties and defect features, other properties show strong correlations. For example, no trend is observed for the corrosion properties in relation to pore average area fraction. However, strong correlations are observed for the corrosion properties as functions of defects maximum area. Corrosion properties linearly deteriorate as the defects maximum area increases. Roughness shows a mixed relationship with pitting potential. Comprehensive discussions on all these effects are presented.
Jonas Stoll et al 2024 J. Electrochem. Soc. 171 054520
Utilizing a direct film coating method (DFCM), such as doctor blade coating, offers a promising approach for efficient and scalable catalyst layer (CL) production for fuel cells. To further widen the understanding of lab-scale DFCM, the present research investigates how different Pt-based catalyst ink formulations coated via doctor blade coating with varying blade gap thickness (BGT) affect the CL quality and catalyst loading. In total, 120 CL samples were prepared by coating 20 different catalyst ink formulations with varying solids content, ionomer-to-carbon (I/C) ratio, and water-to-isopropanol solvent ratio with BGTs of 75, 125, and 200 μm. Inspection of these samples showed that the solvent ratio affects the coating uniformity, with the most uniform films achieved with a ratio of 1.67 or greater. Furthermore, increasing the I/C ratio for a given solids content ink formulation decreases the Pt loading, whereas an I/C ratio above or below 1.0 reduces cell performance due to mass transport or proton conductivity impacts, respectively. In addition, a relationship factor and equations are presented to estimate the solid weight and catalyst loading of the fabricated CL based on the ink formulation and BGT. Overall, this work provides important guidance for lab-scale DFCM fabrication of industrially relevant CLs.
Highlights
Direct film coating is systematically evaluated for catalyst layer fabrication
Impacts of catalyst ink composition and wet film thickness are determined
Practical tools are provided for the estimation of solid weight and catalyst loading
Recommendations for lab-scale fabrication of industrially relevant catalyst layers
Branimir Stamenkovic et al 2024 J. Electrochem. Soc. 171 050554
Unveiling the electrochemistry of solid-state Li2ZrCl6 halide electrolyte, we reveal its triple function as an ion conductor and a supplementary reversible, and sacrificial, electron source/sink. This groundbreaking discovery leads to a remarkable long-term enhancement of the specific capacity of industry-relevant heavily loaded LiFePO4 electrodes by several tens of percent, while significantly amplifying that of Si-based or anode-less full cells through effective compensation for side reactions. We show that these effects can potentially be tuned by adjusting the initial xLiCl-ZrCl4 composition of the solid electrolyte, which may thus become a new and mighty parameter for balancing the two electrodes.
Highlights
We used the partially reversible redox activity of halide LixZrCl4+x electrolyte.
Li2ZrCl6 acts as an ion conductor and a supplementary reversible and sacrificial e−/Li+ source.
It remarkably boosts the specific capacity of thick LiFePO4 electrodes in the 4V region
It acts as sacrificial e- source for Si-based or anode-less full cells.
Reversible and irreversible capacities can betuned by the LixZrCl4+x composition.
Jingjing Liu et al 2024 J. Electrochem. Soc. 171 054521
Water electrolysis has been used to produce green hydrogen, for which identifying optimum operation parameters is crucial to improve its energy efficiency and energy consumption. This paper used a commercial proton exchange membrane (PEM) water electrolyser stack (180 W) to demonstrate the correlation between operating current change, temperature, and water flow rate and their impact on the thermal and electrical performance of the stack. It was found that the current control regime and temperature control can offset the voltage ageing in a long-term operating electrolyser with no negative impact on the H2 production rate. For a controlled decreasing current path, in the medium range of operating current, the stack’s energy efficiency was improved by 5%, and 3.7% specific energy consumption can be saved comparing to the standard operation (57.8 kWh·kg−1H2). The results provide insights into the potential optimisation in operation conditions to further increase cell energy efficiency and reduce energy consumption. This new finding sheds light on developing an energy- and cost-saving operating method for long-term green hydrogen production via water electrolysis.