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.
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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.
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.
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.
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.
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.
Mark E. Orazem and Burak Ulgut 2024 J. Electrochem. Soc. 171 040526
Recent battery papers commonly employ interpretation models for which diffusion impedances are in series with interfacial impedance. The models are fundamentally flawed because the diffusion impedance is inherently part of the interfacial impedance. A derivation for faradaic impedance is presented which shows how the charge-transfer resistance and diffusion resistance are functions of the concentration of reacting species at the electrode surface, and the resulting impedance model incorporates diffusion impedances as part of the interfacial impedance. Conditions are identified under which the two model formulations yield the same results. These conditions do not apply for batteries.
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.
E. Peled and S. Menkin 2017 J. Electrochem. Soc. 164 A1703
The Solid-Electrolyte-Interphase (SEI) model for non-aqueous alkali-metal batteries constitutes a paradigm change in the understanding of lithium batteries and has thus enabled the development of safer, durable, higher-power and lower-cost lithium batteries for portable and EV applications. Prior to the publication of the SEI model (1979), researchers used the Butler-Volmer equation, in which a direct electron transfer from the electrode to lithium cations in the solution is assumed. The SEI model proved that this is a mistaken concept and that, in practice, the transfer of electrons from the electrode to the solution in a lithium battery, must be prevented, since it will result in fast self-discharge of the active materials and poor battery performance. This model provides [E. Peled, in "Lithium Batteries," J.P. Gabano (ed), Academic Press, (1983), E. Peled, J. Electrochem. Soc., 126, 2047 (1979).] new equations for: electrode kinetics (io and b), anode corrosion, SEI resistivity and growth rate and irreversible capacity loss of lithium-ion batteries. This model became a cornerstone in the science and technology of lithium batteries. This paper reviews the past, present and the future of SEI batteries.
Peter M. Attia et al 2022 J. Electrochem. Soc. 169 060517
Lithium-ion batteries can last many years but sometimes exhibit rapid, nonlinear degradation that severely limits battery lifetime. In this work, we review prior work on "knees" in lithium-ion battery aging trajectories. We first review definitions for knees and three classes of "internal state trajectories" (termed snowball, hidden, and threshold trajectories) that can cause a knee. We then discuss six knee "pathways", including lithium plating, electrode saturation, resistance growth, electrolyte and additive depletion, percolation-limited connectivity, and mechanical deformation—some of which have internal state trajectories with signals that are electrochemically undetectable. We also identify key design and usage sensitivities for knees. Finally, we discuss challenges and opportunities for knee modeling and prediction. Our findings illustrate the complexity and subtlety of lithium-ion battery degradation and can aid both academic and industrial efforts to improve battery lifetime.
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Vikas N. Kendre and Sea-Fue Wang 2024 J. Electrochem. Soc. 171 057506
Precise revealing and early detection of 3-Nitro-L-Tyrosine (3-NLT), a biomarker of oxidative stress in biological media is critical for the early treatment of cancer tumorigenic cells and immunologic disorders. In this study, zinc tungstate (ZnWO4) was incorporated with functionalized carbon nanofibers (f-CNF) to form a ZnWO4/f-CNF composite. The composite improves detection of 3-NLT by increasing the electrical conductivity, electrocatalytic activity, and rapid electron transfer kinetics. Various physical characterization techniques were employed to confirm the ZnWO4/f-CNF composite. Electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry were utilized to detect 3-NLT after modifying ZnWO4/f-CNF on glassy carbon electrode (GCE). The ZnWO4/f-CNF/GCE achieved an elevated electrochemically active surface area (0.08 cm2), a linear range of 1.0–117.0 μM, and a low detection limit of 0.07 μM. Finally, the ZnWO4/f-CNF/GCE was tested with bovine serum albumin and tap water in the real sample investigation.
Highlights
A hydrothermal method was used to prepare the ZnWO4/f-CNF electrocatalyst.
ZnWO4/f-CNF nanocomposite displays the owing electrochemical activity towards the detection of 3-Nitro-L-Tyrosine.
The fabricated sensor achieved a good electrocatalytic activity displaying wide linear range and lower LOD.
ZnWO4/f-CNF modified electrode was exhibited the exceptional electrochemical performance in the 3-NLT spiked water and BSA samples.
Yang Zhou et al 2024 J. Electrochem. Soc. 171 056506
Electrocatalytic water splitting for hydrogen production is promising, but its practical application is limited by the sluggish kinetics of the anodic oxygen evolution reaction (OER) and the less valuable oxygen by-product. Hence, replacing OER with a thermodynamically favorable methanol oxidation reaction (MOR) and coupling with value-added formate generation on the anode is an energy-saving and effective scheme. In this work, we report a self-supporting bifunctional electrocatalyst MoN/Ni3N/NF, which exhibits excellent hydrogen evolution reaction catalytic activity and stability, requiring overpotentials of only 18 and 68 mV to reach current densities of −10 and −100 mA cm−2, respectively. Moreover, the catalyst's performance minimally deteriorates after long-standing chronopotentiometry measurements (−100 mA cm−2@150 h). When MOR is used instead of OER, the required potential drops by 200 mV to 1.38 V at a current density of 100 mA cm−2 and MoN/Ni3N/NF also demonstrates splendid catalytic stability towards OER and MOR. Finally, a two-electrode system employing MoN/Ni3N/NF as a bifunctional electrocatalyst only requires a cell voltage of 1.40, 1.68 V to achieve current densities of 10 and 100 mA cm−2, respectively. The coupled electrolyzer also exhibits high faradaic efficiency for producing cathodic H2 (100%) and anodic formate (90%).
Junyi Tao et al 2024 J. Electrochem. Soc. 171 054513
Nickel (Ni) film on patterned Ni- yttria-stabilized zirconia (YSZ) anode shows dynamic spreading and splitting during solid oxide fuel cell (SOFC) operation, where wettability of Ni on YSZ is greatly enhanced (Z. Jiao, N. Shikazono, J. Power Sources 396 119–123, 2018). In the present study, a physics-informed neural network (PINN) constrained by Cahn-Hilliard equation of phase field model is proposed to estimate the unknown parameters for predicting dynamic Ni movements of the patterned Ni-YSZ anode. The unknown parameters such as interface thickness and mobility are inversely inferred by PINN using top-view images obtained from the operando experiments. Obtained excess surface diffusivity values were three to four orders of magnitude larger than the values reported for surface diffusion in the literature. It is therefore considered that Ni spreading and splitting of patterned anode cannot be simply explained by surface diffusion, and other mechanisms should be introduced.
Francesco Marino et al 2024 J. Electrochem. Soc. 171 054511
In the perspective of the transition of gas grids towards hydrogen/natural gas blends or even pure hydrogen, Solid Oxide Fuel Cells "SOFC" could play a crucial role as efficient and clean stationary Combined Heat and Power systems, flexibly operating on different feedstocks. A solid oxide fuel cell short stack is analyzed experimentally under different fuel gas compositions which emulate different gas grid transition scenarios. The testing campaign is defined with the aid of a preliminary system-level simulation which assesses system architecture and operating strategy (off-gas recirculation, external reforming, etc). Experimental tests (polarization curves and performance/efficiency maps) are run in different operating conditions in terms of fuel utilization and temperature in three gas composition scenarios. To assess the efficiency of the SOFC unit under the different feedstock operation, different formulations of stack and system efficiencies are proposed and analyzed, based on the boundary conditions considered for the input/output energy streams. Experimental results were key to evaluate the different efficiency definitions proposed; albeit the highest voltage/power is obtained with the 100% H2 scenario, the efficiency may be higher with 100% NG and blend scenarios, due to the lower energy content of the input fuel.
Huayu Yu et al 2024 J. Electrochem. Soc. 171 050520
Thermal batteries have high specific energy and can operate in harsh environments, making them suitable for military and aerospace applications. However, existing cathode materials do not meet the high power and energy density requirements of advanced military systems. This urgent need motivates the development of new high-performance cathodes. Sulfates, as polyanionic compounds with highly electronegative anions, often exhibit higher voltages than phosphates. This high voltage should match the high power output needs of thermal battery cathode, though few studies explore sulfate. In this of case, NiSO4, CoSO4, and CuSO4 were investigated as cathode materials for thermal battery. They all have higher voltage and greater specific capacity at 450 °C (cut-off voltage is 75% of peak voltage) than at 500 °C or higher. Compared with other temperatures, the peak voltage of CoSO4 cathode at 450 °C is 2.23 V and the specific capacity is 296 mAh g−1. While CuSO4 showed modest capacity at 450 °C, its high voltage of 2.5 V makes it a promising high energy density cathode. This work provides new insights into cathode materials for high power and energy density thermal batteries.
Highlights
Polyanionic sulfate was first used as the cathode material of thermal battery.
The cobalt sulfate exhibits a specific energy of 652 Wh kg−1 at 450 °C.
Sulfate may be a material for high voltage and high energy thermal batteries.
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Durgalakshmi Dhinasekaran et al 2024 J. Electrochem. Soc. 171 057505
Uric acid (UA) is an important biomarker in blood to diagnosis diseases linked with hyperuricemia. Although several detection methods exist for UA sensing, electrochemical method has emerged as a promising alternative. For effective performance of a biosensor, the choice of electroactive material plays a crucial role. The developed electrodes are enzymatic and non-enzymatic with modified nano-structures of metal oxides, ferrites and carbon-based materials. Several combinations of nanocomposites using metal oxides with carbon-based compounds show promising results for biosensor applications. This is attributed to its functional groups, higher surface area and porous nature that can improve the sensing performance as it requires only quick-time processing with inexpensive and direct detection methods. The electrochemical method uses anodic peak current which is the analytical signal to sense the electrochemical oxidation of UA. This technique paves a new way to make electrodes for point-of-detection devices in near future. It could be the next generation of non-invasive analysis for food hygiene as well as biomedical and clinical applications. This review focuses on materials used in electrochemical sensing of UA and discusses on the application of different electrochemical techniques in UA detection.
Jiashuai Wang et al 2024 J. Electrochem. Soc. 171 040527
The growing demand for energy storage application has facilitated the development of Li-ion rechargeable batteries (LIBs). As such, there is an urgent need to design electrodes with a high specific energy and long cycle life. The evolution of conventional LIBs cathode materials in past 30 years has arrived at a bottleneck. Fortunately, the finding of the lithium-rich cation disordered rocksalt (DRXs) has largely broadened the element ranges of the promising cathode in the past several years. Compared with the classical cation-ordered oxides, the DRXs display a large charge storage capacity based on both transition metal and oxygen redox capacity. In addition, their wide compositional space and cobalt-free characteristic would greatly reduce production costs in promoting the commercialization process. Herein, we make an overview of the recent progress for DRXs materials, in terms of their compositions and structure, Li diffusion, charge storage mechanisms, and different redox centra-based system. The key challenges to practical application are also discussed. Last but not least, in order to design high-performance DRXs, we outlined perspectives in developing DRXs for the next generation of LIB cathodes.
Pooja Saxena and Prashant Shukla 2024 J. Electrochem. Soc. 171 047504
Wearable sensors offer a non-invasive, continuous, and personalized approach to monitor various physiological and environmental parameters. Among the various materials used in the fabrication of wearable sensors, polymers have gained significant attention due to their versatile properties, low cost, and ease of integration. We present a comprehensive review of recent advances and challenges in the development of polymer-based wearable sensors. We begin by highlighting the key characteristics of wearable sensors, emphasizing their potential applications and advantages. Subsequently, we delve into the various types of polymers employed for sensor fabrication, such as conductive polymers, elastomers, and hydrogels. The unique properties of each polymer and its suitability for specific sensing applications are discussed in detail. We also address the challenges faced in the development of polymer-based wearable sensors and describes the mechanism of action in these kinds of wearable sensor-capable smart polymer systems. Contact lens-based, textile-based, patch-based, and tattoo-like designs are taken into consideration. Additionally, we paper discuss the performance of polymer-based sensors in real-world scenarios, highlighting their accuracy, sensitivity, and reliability when applied to healthcare monitoring, motion tracking, and environmental sensing. In conclusion, we provide valuable insights into the current state of polymer-based wearable sensors, their fabrication techniques, challenges, and potential applications.
Bianca-Maria Tuchiu et al 2024 J. Electrochem. Soc. 171 047502
Topical treatments rely on drugs that play a crucial role in addressing skin and mucous membrane disorders. Therefore, it is highly needed to utilize accurate analytical techniques that can determine the concentration of these chemicals in various sample matrices, including pharmaceuticals, food, and water. Currently, electrochemical sensors are predominantly used in specific fields such as biomedical, industrial, and environmental monitoring, while they have not yet been incorporated into the pharmaceutical manufacturing industry. However, electrochemical methods employing an expanding range of sensors provide a reliable, cost-effective, and efficient substitute for classical analytical methods. Their potential is highly favorable, offering possibilities for simultaneous determination, miniaturization, and real-time on-site monitoring. This work covers numerous sensors designed between 2020 and 2023 for the determination of topical drugs, highlighting their respective benefits and drawbacks while illuminating emerging trends. Moreover, it discusses the correlation between the used materials and the ease of manufacturing, to the achieved results, including dynamic range, detection limit, sensitivity, and selectivity. This work aims to serve as a valuable resource for researchers, engineers, and policymakers in the evolving field of electrochemical sensing by providing guidance and facilitating decision-making, which could lead to significant innovations in sensor technology.
Richard Bertram Church and A. John Hart 2024 J. Electrochem. Soc. 171 040512
Three-dimensional (3D) battery architectures have been envisioned to enable high energy density electrodes without the associated power drop experienced by planar cells. However, the development of 3D cells is hampered by difficulties producing conformal solid-state electrolytes (SSE), solid polymer electrolytes (SPE) and gel polymer electrolytes (GPE) that are pinhole-free and have adequate ionic conductivities. Fortunately, electrolytes in 3D cells are often utilized at lower thickness, which may compensate the decreased ionic conductivity. Here, we comprehensively review potential 3D SSE, SPE and GPE electrolyte materials by compiling their thickness and room temperature ionic conductivity. We use area specific resistance (ASR) as a metric to compare 3D electrolytes with one another and conventional electrolytes. We find that certain process-material combinations, such as atomic layer deposition of SSEs, electrodeposition of SPEs and GPEs, and initiated chemical vapor deposition of SPEs demonstrate ASRs beneath the interfacial impedances of Li-based systems and approach state-of-the-art electrolytes. We also comment on additional factors, such as electrochemical stability, that should be evaluated when determining 3D electrolyte suitability. Future research should focus on adapting known materials chemistries for conformal deposition techniques to further improve the ionic conductivity, as these techniques are capable of producing the necessary thicknesses and conformality.
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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.
Leonardo I. Astudillo and Hubert A. Gasteiger 2023 J. Electrochem. Soc. 170 124512
A major degradation mechanism of polymer electrolyte membrane fuel cells (PEMFCs) in transportation applications is the loss of the electrochemically active surface area (ECSA) of platinum cathode catalysts upon dynamic load cycling (resulting in cathode potential cycles). This is commonly investigated by accelerated stress tests (ASTs), cycling the cell voltage under H2/N2 (anode/cathode). Here we examine the degradation of membrane electrode assemblies with Vulcan carbon supported Pt catalysts over extended square-wave voltage cycles between 0.6-1.0 VRHE at 80 °C and 30%-100% RH under either H2/N2 or H2/Air; for the latter case, differential reactant flows were used, and the lower potential limit is controlled to correspond to the high-frequency resistance corrected cell voltage, assuring comparable aging conditions. Over the course of the ASTs, changes of the ECSA, the hydrogen crossover current, the proton conduction resistance and the oxygen transport resistance of the cathode electrode, as well as the differential-flow H2/O2 and H2/Air performance at 80 °C/100% RH were monitored. While the ECSA loss decreases with decreasing RH, it is independent of the gas feeds. Furthermore, the H2/Air performance loss only depends on the ECSA loss. ASTs under H2/N2 versus H2/Air only differ with regards to the chemical/mechanical degradation of the membrane.
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Bühre et al
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.
Bian et al
Spherical graphite tailings (SGT) as the anode electrode for a lithium-ion battery not only improves the utilization value of SGT as solid waste, but also demonstrates the cleaner production of natural flake graphite (NG) compared with artificial graphite. However, SGT anodes present issues regarding rate performance and cycle stability due to the anisotropy structure and the instability of the solid electrolyte interface (SEI). In this work, a composite anode with isotropic structure was prepared by granulation of high-sulfur coal (HSC) and SGT, while an artificial SEI was prepared utilizing polyether amine/polyvinyl pyrrolidone (PEA/PVP) crosslinked polymer. Results showed that the coke from HSC pyrolysis enhanced the isotropy of the composite anode and improved its rate performance. Compared with SGT, the capacity retention rate of the sample (OSGT-50%OHSC) after oxidation - pyrolysis at a high current density of 5.0 A g-1 increased from 7.2% to 25.8%. Additionally, the PEA/PVP artificial SEI strengthened the cycle stability of the anode. After 1000 cycles, the capacity retention rate increased from 22.5% to 70.3%. The artificial SEI effectively avoided direct contact between the anode and the electrolyte, increasing the initial coulombic efficiency from 70.3% to 77.1%.
Cao et al
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.
Lv et al
MnMoO4 has excellent electrochemical properties and is widely used in the field of electrochemistry. In this study, MnMoO4 with rod-like structure was successfully prepared by simple solvothermal method and used as sensitive material for gas sensors. The gas sensing performance shows that the response of MnMoO4-based sensor to 50 ppm triethylamine is 224.2, which is 2.3 times higher than that of pure MoO3. That reason why MnMoO4 exhibits better sensitivity is that the increase of oxygen vacancy content gives the surface of MnMoO4 material abundant active sites. In addition, its large baseline resistance is also conducive to the improvement of gas sensitivity. These factors make the MnMoO4-based sensor exhibit high response to triethylamine. What’s more, the sensor also has excellent selectivity, satisfactory repeatability, and long-term stability to triethylamine under chemical sensitization and synergistic action. This work provides a new thinking for the application of MnMoO4 in gas sensors.
Wen et al
Rapid and accurate detection of hydrogen peroxide (H2O2), an important reactive oxygen species (ROS) released from living cells, is of great significance for early diagnosis of tumors. Here, a high sensitive enzyme-free electrochemical sensor for the detection of H2O2 released from living cells was constructed based on MXene@ZIF-8@Pt NPs nanocomposites. Through the characterization of physical and chemical properties, it was observed that Pt NPs with excellent catalytic activity were uniformly supported on MXene@ZIF-8, which exhibited excellent conductivity and large specific surface area. Thanks to the significantly enhanced catalytic activity derived from the successful integration of MXene, ZIF-8 and Pt NPs, under the optimal conditions, the sensing platform based on MXene@ZIF-8@Pt NPs exhibited a wide linear range from 355.4 nM to 21.75 mM, with a limit of detection as low as 120.9 nM, while showing satisfactory reproducibility and selectivity. Furthermore, the developed electrochemical sensor enables real-time monitoring of H2O2 released from living Hela cells under N-formylmethionyl-leucyl-phenylalanine stimulation. Overall, the MXene@ZIF-8@Pt NPs developed in this article will become a promising candidate in monitoring physiological processes.
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Francesco Marino et al 2024 J. Electrochem. Soc. 171 054511
In the perspective of the transition of gas grids towards hydrogen/natural gas blends or even pure hydrogen, Solid Oxide Fuel Cells “SOFC” could play a crucial role as efficient and clean stationary Combined Heat and Power systems, flexibly operating on different feedstocks. A solid oxide fuel cell short stack is analyzed experimentally under different fuel gas compositions which emulate different gas grid transition scenarios. The testing campaign is defined with the aid of a preliminary system-level simulation which assesses system architecture and operating strategy (off-gas recirculation, external reforming, etc). Experimental tests (polarization curves and performance/efficiency maps) are run in different operating conditions in terms of fuel utilization and temperature in three gas composition scenarios. To assess the efficiency of the SOFC unit under the different feedstock operation, different formulations of stack and system efficiencies are proposed and analyzed, based on the boundary conditions considered for the input/output energy streams. Experimental results were key to evaluate the different efficiency definitions proposed; albeit the highest voltage/power is obtained with the 100% H2 scenario, the efficiency may be higher with 100% NG and blend scenarios, due to the lower energy content of the input fuel.
Lena Viviane Bühre et al 2024 J. Electrochem. Soc.
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.
Sri Harsha Akella et al 2024 J. Electrochem. Soc. 171 050519
Nickel-rich layered oxide cathode materials with low cobalt content, such as LiNi0.90Mn0.05Co0.05O2 (NMC90), have the potential to enable cost-effective, high-energy-density lithium-metal batteries. However, NMC90 cathode materials are prone to severe parasitic reactions at higher voltages during prolonged cycling. The addition of small percentages of electrolyte additives to the neat commercial electrolyte can significantly enhance the overall electrochemical performance of lithium-metal batteries. This study investigates the effects of zinc triflate (Zn(Otf)2) as an electrolyte additive on the enhancement of the electrochemical performances of lithium-metal batteries comprising nickel-rich layered oxide cathode materials. X-ray photoelectron spectroscopy analysis revealed that Zn(Otf)2 decomposition leads to enhanced fluorination at the interfacial layers, which contributes to improved chemical stability. Utilizing operando electrochemical mass spectroscopy, we demonstrate that Zn(Otf)2 additives effectively suppress the electrolyte degradation, which is otherwise detrimental to electrochemical performance. Electrochemical studies show that the inclusion of only ∼1% Zn(Otf)2 as additive in neat commercial electrolyte enhances the electrochemical performance indicated by a 10% improvement in discharge capacity after 150 cycles. This study paves the way for researchers to develop novel fluorinated triflate based electrolyte additives aimed at enhancing the stabilization of interfaces for lithium ion, and potentially also Li-metal batteries.
Hannes Liepold et al 2024 J. Electrochem. Soc. 171 054509
Recent developments in hydrocarbon-based proton exchange membrane fuel cells have significantly narrowed the performance gap compared to state-of-the-art cells using perfluorosulfonic acid ionomers (PFSA). However, balancing protonic resistance and gas transport resistance in the catalyst layer remains a challenge at low humidity. This study investigates gas transport resistance and its components in sulfonated phenylated polyphenylene-based catalyst layers using various limiting current methods. Results show that increasing the dry ionomer to carbon (I/C) ratio from 0.2 to 0.4, a measure to catch up with protonic resistance of PFSA-based catalyst layers, significantly increases gas transport resistance in the cathode catalyst layer by 28 %. The data suggest a strong correlation between local gas transport resistance and IEC. A high IEC is beneficial for the gas transport through the ionomer film. However, at low ionomer volume fractions the local gas transport resistance is dominated by the I/C independent interfacial resistance. Furthermore, a low IEC hydrocarbon ionomer, such as Pemion® PP1-HNN4–00-X (IEC = 2.5 meq g−1), not only exhibits a beneficial interfacial resistance, but also suppresses excessive ionomer swelling, which typically occurs during operating conditions where liquid water is forming.
Arvydas Survila et al 2024 J. Electrochem. Soc. 171 056505
Anodic LS voltammograms of the alkaline Cu|Cu(II), glycine system were converted into mass-transport corrected Tafel plots considering that the glycinate anion L− takes part in the first stage of copper ionization. The anodic current density was normalized relative to the surface concentration of L− species, which was determined using the mass transfer model of chemically interacting species. The lability of the system was assessed based on available kinetic characteristics and specific experimental data. To linearize the Tafel plots, corrections were made to account for the insufficient mobility of the proton attached to glycine amino group. Obtained Tafel constants indicate that the second step of copper ionization, involving the oxidation of the intermediate copper(I)-glycine complex, is the rate-determining step.
Emre Burak Boz et al 2024 J. Electrochem. Soc.
Carbon-based porous electrodes are commonly employed in electrochemical technologies as they provide a high surface area for reactions, an open structure for fluid transport, and enable compact reactor architectures. In electrochemical cells that sustain liquid electrolytes (e.g., redox flow batteries, CO2 electrolyzers, capacitive deionization), the nature of the interaction between the three phases - solid, liquid and gas - determines the accessible surface area for reactions, which fundamentally determines device performance. Thus, it is critical to understand the correlation between the electrolyte infiltration in the porous electrode and the resulting accessible surface area in realistic reactor architectures. To tackle this question, here we simultaneously perform neutron radiography with electrochemical measurements to correlate macroscopic electrode saturation/wetting with accessible surface area. We find that for untreated electrodes featuring neutral wettability with water, the electrode area remains underutilized even at elevated flow rates, both for interdigitated and parallel flow fields. Conversely, increasing the electrode hydrophilicity results in an order-of-magnitude increase in accessible surface area at comparable electrode saturation, and is less influenced by the electrolyte flow rate. Ultimately, we reveal useful correlations between reactor architectures and electrode utilization and provide a method that is broadly applicable to flow electrochemical reactors.
Selva Chandrasekaran Selvaraj et al 2024 J. Electrochem. Soc.
We performed large-scale molecular dynamics simulations based on a machine-learning force field (MLFF) to investigate the Li-ion transport mechanism in cation-disordered Li3TiCl6 cathode at six different temperatures, ranging from 25°C to 100°C. In this work, the deep neural network method and data generated by ab-initio molecular dynamics (AIMD) simulations were deployed to build a high-fidelity MLFF. Radial distribution functions, Li-ion mean square displacements (MSD), diffusion coefficients, ionic conductivity, activation energy, and crystallographic direction-dependent migration barriers were calculated and compared with corresponding AIMD and experimental data to benchmark the accuracy of the MLFF. Our MSD analysis captured both the self and distinct parts of Li-ion dynamics. The latter reveals that the Li-ions are involved in anti-correlation motion that was rarely reported for solid-state materials. The obtained trajectory from molecular dynamics infers that the Li-ion transportation is mainly through interstitial hopping, which was confirmed by intra- and inter-layer Li-ion displacement with respect to simulation time. Ionic conductivity (1.06 mS/cm) and activation energy (0.29eV) calculated by our simulation are highly comparable with that of experimental values. Overall, the MLFF-based simulation is a promising method to explain the intricate electrochemical properties of the Li3TiCl6 cathode with remarkably reduced computational time
C. Grosselindemann et al 2024 J. Electrochem. Soc. 171 054508
The performance of a solid oxide cell (SOC) depends on the operating environment. Regarding single cell tests with ideal contacting (gold, platinum, nickel meshes) and inert flow fields (Al2O3), performance is limited by intrinsic losses in the cell. Contact losses and poisoning effects are minimized. In a SOC-stack with metallic interconnectors, performance is affected by contact resistances, chromium (Cr) evaporation, and limitations in gas supply. Here, 1 cm2 single cells were tested with a stack-like contact applying metallic flow fields made from three different steel grades (Crofer 22 APU, AISI 441, UNS S44330) with and without a cerium-cobalt PVD-coating. Cell performance and losses were analyzed by IV-characteristics, impedance spectroscopy, and DRT analysis. For all uncoated interconnectors, significant performance losses due to increased contact losses and air electrode polarization were observed, which is attributed to Cr-oxide scale formation on the metallic interconnectors and Cr-poisoning of the air electrode as revealed by scanning electron microscopy-energy-dispersive X-ray spectroscopy. A CeCo-coating leads to similar oxide scales irrespective of the substrate material. Moreover, with the coating the electrochemical performance drastically improved due to decreased contact losses and an effective blocking of Cr-evaporation leading to a cell performance close to the ideal case for all three steel grades.
Yuki Tsuda et al 2024 J. Electrochem. Soc. 171 054507
This study investigates the effect of five amino acids on the electrodeposition of Cu to enhance its electrocatalytic performance in CO2 reduction reactions (CO2RR). The amino acids significantly influenced the deposition potential, crystallite size, and surface morphology of the electrodeposited Cu. Electrodeposited Cu with amino acids exhibit significantly smaller crystallites and higher particle density on carbon paper relative to amino acid-free samples. The integration of amino acids into the electrodeposited Cu was confirmed via high-angle annular dark-field scanning transmission electron microscopy, energy dispersive X-ray spectroscopy and hard X-ray photoelectron spectroscopy. All electrodeposited Cu exhibits a higher faradaic efficiency (FE) in the electrochemical reduction of CO2 to CH4 relative to Cu foil (24.2%), regardless of the presence or absence (55.0%) of amino acids when the electrolysis was conducted at −1.27 V vs RHE. Electrodeposited Cu with L-histidine, containing an imidazole group, demonstrates a higher FE of CH4 (67.6%) and effectively suppressed the hydrogen evolution reaction, highlighting the crucial role of amino acid functional groups, particularly imidazole, in augmenting the electrochemical conversion of CO2 to CH4. The study demonstrates the critical influence of specific functional groups in amino acids on the catalytic efficiency of electrodeposited Cu in CO2RR electrocatalysis applications.
Haoran Ding et al 2024 J. Electrochem. Soc.
Terephthalic acid is conventionally synthesized through the AMOCO process under harsh conditions, making milder electrosynthesis routes desirable. Electrooxidation of p-xylene has been demonstrated but the degree of oxidation is limited, resulting in low terephthalic acid yields. Here, we demonstrate a process with two electrochemical steps enabling the complete oxidation of p-xylene into terephthalic acid. The first electrochemical step achieves C-H activation of p-xylene using electrochemically generated bromine as a mediator, while the second electrochemical step does alcohol oxidation of 1,4-benzenedimethanol into terephthalate on NiOOH. The divided cell in the first step simultaneously generates acid and base that are utilized subsequently, negating the need of external acid and base addition and thus offering a cost competitive synthesis route. The competing bromide oxidation in the second step is suppressed by using constant voltage electrolysis at 0.50 V, where an optimal yield of terephthalic acid of 81% is achieved.