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
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.
Peter Keil et al 2016 J. Electrochem. Soc. 163 A1872
In this study, the calendar aging of lithium-ion batteries is investigated at different temperatures for 16 states of charge (SoCs) from 0 to 100%. Three types of 18650 lithium-ion cells, containing different cathode materials, have been examined. Our study demonstrates that calendar aging does not increase steadily with the SoC. Instead, plateau regions, covering SoC intervals of more than 20%–30% of the cell capacity, are observed wherein the capacity fade is similar. Differential voltage analyses confirm that the capacity fade is mainly caused by a shift in the electrode balancing. Furthermore, our study reveals the high impact of the graphite electrode on calendar aging. Lower anode potentials, which aggravate electrolyte reduction and thus promote solid electrolyte interphase growth, have been identified as the main driver of capacity fade during storage. In the high SoC regime where the graphite anode is lithiated more than 50%, the low anode potential accelerates the loss of cyclable lithium, which in turn distorts the electrode balancing. Aging mechanisms induced by high cell potential, such as electrolyte oxidation or transition-metal dissolution, seem to play only a minor role. To maximize battery life, high storage SoCs corresponding to low anode potential should be avoided.
George E. Blomgren 2017 J. Electrochem. Soc. 164 A5019
This year, the battery industry celebrates the 25th anniversary of the introduction of the lithium ion rechargeable battery by Sony Corporation. The discovery of the system dates back to earlier work by Asahi Kasei in Japan, which used a combination of lower temperature carbons for the negative electrode to prevent solvent degradation and lithium cobalt dioxide modified somewhat from Goodenough's earlier work. The development by Sony was carried out within a few years by bringing together technology in film coating from their magnetic tape division and electrochemical technology from their battery division. The past 25 years has shown rapid growth in the sales and in the benefits of lithium ion in comparison to all the earlier rechargeable battery systems. Recent work on new materials shows that there is a good likelihood that the lithium ion battery will continue to improve in cost, energy, safety and power capability and will be a formidable competitor for some years to come.
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.
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.
Loraine Torres-Castro et al 2024 J. Electrochem. Soc. 171 020520
The rate of electric vehicle (EV) adoption, powered by the Li-ion battery, has grown exponentially; largely driven by technological advancements, consumer demand, and global initiatives to reduce carbon emissions. As a result, it is imperative to understand the state of stability (SoS) of the cells inside an EV battery pack. That understanding will enable the warning of or prevention against catastrophic failures that can lead to serious injury or even, loss of life. The present work explores rapid electrochemical impedance spectroscopy (EIS) coupled with gas sensing technology as diagnostics to monitor cells and packs for failure markers. These failure markers can then be used for onboard assessment of SoS. Experimental results explore key changes in single cells and packs undergoing thermal or electrical abuse. Rapid EIS showed longer warning times, followed by VOC sensors, and then H2 sensors. While rapid EIS gives the longest warning time, with the failure marker often appearing before the cell vents, the reliability of identifying impedance changes in single cells within a pack decreases as the pack complexity increases. This provides empirical evidence to support the significant role that cell packaging and battery engineering intricacies play in monitoring the SoS.
Yuriy V. Tolmachev 2023 J. Electrochem. Soc. 170 030505
We present a quantitative bibliometric study of flow battery technology from the first zinc-bromine cells in the 1870's to megawatt vanadium RFB installations in the 2020's. We emphasize, that the cost advantage of RFBs in multi-hour charge-discharge cycles is compromised by an inferior energy efficiency of these systems, and that there are limits on the efficiency improvement due to internal cross-over and the cost of power (at low current densities) and due to an acceptable pressure drop (at high current densities). Differences between lithium-ion and vanadium redox flow batteries (VRFBs) are discussed from the end-user perspective. We conclude, that the area-specific resistance, cross-over current and durability of contemporaneous VRFBs are appropriate for commercialization in multi-hour stationary energy storage markets, and the most import direction in the VRFB development today is the reduction of stack materials and manufacturing costs. Chromium-iron RFBs should be given a renewed attention, since it seems to be the most promising durable low-energy-cost chemistry.
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.
Latest articles
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Shufang Shi et al 2024 J. Electrochem. Soc. 171 046504
The hydrogen peroxide oxidation reaction (HPOR) plays a vital role in the emerging H2-H2O2 cycle energy storage system, in which the rational design of HPOR electrocatalyst is essential for achieving high system efficiency. Herein, we establish the HPOR activity trends using structurally well-defined metal phthalocyanines (MPc) as model catalysts via a combined experimental and computational approach. The measured activity sequence follows the order of CoPc > FePc > MnPc > ZnPc > H2Pc > NiPc > CuPc based on their site-normalized exchange current (i0-s). Theoretical calculations indicate that the binding free energy of hydroperoxyl intermediate, HOO*, on MPc (ΔGHOO*) is the activity descriptor for HPOR. A volcano-type activity trend is observed by correlating the logarithm of i0-s (logi0-s) with the ΔGHOO* values and agrees with the theoretical predictions. This HPOR activity trend provides insights into the design of highly active electrocatalysts for HPOR and related energy applications.
Minyung Song et al 2024 J. Electrochem. Soc. 171 040532
This study investigates the efficacy of a polymer coating, PVdC-co-AN, in enhancing the stability and reversibility of the electrochemical Mg anode interface. Coated electrodes, immersed in a 0.25 M Mg(TFSI)2−0.50 M MgCl2/dimethoxyethane (DME) electrolyte, exhibit notable improvements. Cyclic voltammetry demonstrates consistent behavior with the coated electrode, while the uncoated electrode changes dramatically. During extended open circuit potential conditions, the coated electrode maintains much higher coulombic efficiency (93%) compared to the uncoated electrode (62%). Galvanostatic cycling test over 200 cycles further show the benefits of the PVdC-co-AN coating, decreasing the overpotential of Mg plating and improving long-term stability. The coated electrodes also demonstrate improved rate capability at higher current densities. Surface analysis reveals differences in the formation of byproducts between the coated and uncoated electrodes, indicating a more stable and uniform interface in the former. Nuclear magnetic resonance (NMR) spectroscopy suggests that the polymer influences ion mobility through tuning the solvation environments which results in better kinetics and fewer byproducts. In summary, the study affirms that the PVdC-co-AN coating significantly improves the stability and performance of Mg electrochemistry, offering a promising advancement for practical battery applications.
Ryan C. Hill et al 2024 J. Electrochem. Soc. 171 040530
Long-duration energy storage (LDES) is critical to a stable, resilient, and decarbonized electric grid. While batteries are emerging as important LDES devices, extended, high-power discharges necessary for cost-competitive LDES present new materials challenges. Focusing on a new generation of low-temperature molten sodium batteries, we explore here unique phenomena related to long-duration discharge through a well-known solid electrolyte, NaSICON. Specifically, molten sodium symmetric cells at 110 °C were cycled at 0.1 A cm−2 for 1–23 h discharges. Longer discharges led to unstable overpotentials, reduced resistances, and decreased electrolyte strength, caused by massive sodium penetration not observed in shorter duration discharges. Scanning electron microscopy informed mechanisms of sodium penetration and even "healing" during shorter-duration cycling. Importantly, these findings show that traditional, low-capacity, shorter-duration tests may not sufficiently inform fundamental materials phenomena that will impact LDES battery performance. This case highlights the importance that candidate LDES batteries be tested under pertinent long-duration conditions.
Marek Haššo et al 2024 J. Electrochem. Soc. 171 047517
The presented study focuses on the development and optimization of a powerful electroanalytical platform for the direct quantification of diazepam (DZP). This innovative approach integrates a batch injection analysis (BIA) system with a screen-printed electrode arrangement employing square-wave adsorptive stripping voltammetry (SWAdSV). The BIA-SWAdSV method underwent a comprehensive evaluation, wherein various experimental and instrumental parameters were systematically examined in detail. Beneficial analytical performance for detecting DZP was attained in Britton-Robinson buffer with pH 6.0, with an amplitude of 75 mV, a frequency of 10 Hz, a deposition potential of –1.2 V, a deposition time of 150 s, an injection volume of 75 μl, a dispensing rate of 7 μl s−1 and without stirring during the deposition step. Under these conditions, the proposed BIA-SWAdSV method demonstrated an adequately broad linear concentration range from 5 μM to 40 μM (R2 = 0.997) with a micromolar limit of detection (2.0 μM) and a satisfactory precision (RSD = 5.0%). The practical applicability of the newly established and powerful analytical protocol was confirmed through the analysis of pharmaceuticals and a fortified samples of an alcoholic drink (rum) associated with potential criminal activities involving DZP abuse.
Farzaneh Hoseynidokht et al 2024 J. Electrochem. Soc. 171 047516
Neuromyelitis optica (NMO) is a severe and disabling neurodegenerative disorder of the central nervous system (CNS). Neuromyelitis optica-Immunoglobulin G (NMO-IgG) is a serum IgG autoantibody almost exclusively present in NMO patients, which helps to differentiate NMO from other CNS disorders. Developing standardized and user-friendly assays remains a significant challenge in making NMO-IgG testing widely available. Label-free methods are simpler and faster, without additional reagents and procedures. Here, we present a peptide-based label-free electrochemical biosensor for detecting aquaporin-4 antibodies (AQP4-Abs) using extracellular AQP4 to diagnose NMO disease via the DPV electrochemical method. We have developed a novel approach in which the E loop of extracellular AQP4 is bemployed to detect NMO. 3 phenylalanines (Phe) were annexed to the C terminal, and because phenylalanine has a benzene ring, it can have π-π interaction with the benzene ring of carbon nanotube (CNT). In the designated platform, instead of using functional groups with complex and multi-step processes for immobilizing on the electrode surface, we used Nickel-Metal−organic framework /CNT as a novel modifier for measuring AQP4 antibodies with a simple, cheap, and accessible synthesis method. The developed sensor can detect antibodies with detection limit and quantification of 6.2 and 10.0 pg ml−1, respectively (S/N = 3). Also, superb sensitivity of the biosensor was attained as 28.8 μA mL ng−1 cm−2, confirming that the sensor has great potential for clinical application as a diagnostic test.
Review articles
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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.
Raphaël Gass et al 2024 J. Electrochem. Soc. 171 034511
Technologies based on the use of hydrogen are promising for future energy requirements in a more sustainable world. Consequently, modelling fuel cells is crucial, for instance, to optimize their control to achieve excellent performance, to test new materials and configurations on a limited budget, or to consider their degradation for improved lifespan. To develop such models, a comprehensive study is required, encompassing both well-established and the latest governing laws on matter transport and voltage polarization for Proton Exchange Membrane Fuel Cells (PEMFCs). Recent articles often rely on outdated or inappropriate equations, lacking clear explanations regarding their background. Indeed, inconsistent understanding of theoretical and experimental choices or model requirements hinders comprehension and contributes to the misuse of these equations. Additionally, specific researches are needed to construct more accurate models. This study aims to offer a comprehensive understanding of the current state-of-the-art in PEMFC modeling. It clarifies the corresponding governing equations, their usage conditions, and assumptions, thus serving as a foundation for future developments. The presented laws and equations are applicable in most multi-dimensional, dynamic, and two-phase PEMFC models.
Editor's Choice
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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.
Accepted manuscripts
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Newman et al
Free-standing conducting polymer films, polypyrrole doped with dodecylbenzene sulfonate, were obtained with electrochemical delamination by using redox cycling to delaminate electropolymerized film from the substrate. The use of electrochemical delamination to obtain thinner films than mechanical peeling and the effect of different electropolymerization substrates was investigated. The free-standing films were characterized with electrochemical filling efficiency and scanning electron microscopy. Electrochemical delamination allowed thin free-standing films <10 μm and <1 μm thick to be obtained from 304 stainless steel and gold substrates, respectively. The thinnest films obtainable from 304 stainless steel were limited by the electropolymerization charge density needed for complete film growth and not by electrochemical delamination. The filling efficiency of the films did not appear to be decreased by electrochemical delamination. These findings show the utility of electrochemical delamination to obtain thin free-standing films that also have the benefits of electropolymerization.
Ngo Xuan et al
Insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures is important in the rational design of functional nanostructures for realizing high-performance electrochemical sensors. This study focuses on elucidating the effect of the crystalline phase on the electron transfer kinetics and electrocatalytic activity of iron(III) oxide. The α-FeOOH, γ-Fe2O3, and α-Fe2O3 nanorods were designed by using a simple chemical method and calcining process. The phase-dependent difference in the electron transfer kinetics and electrocatalytic activity toward the sensitive response of chloramphenicol (CAP) is observed by the transformation from α-FeOOH to γ-Fe2O3, and from α-FeOOH to α-Fe2O3 nanorods. We found that the oxygen vacancies formed in phase transformation from α-FeOOH to α-Fe2O3 is a key factor in promoting the electrochemical reduction of chloramphenicol. The α-Fe2O3 nanorods-based electrochemical sensors showed a linear response in the CAP concentration range from 0.1 to 75 µM with a limit of detection of 60 nM and an electrochemical sensitivity of 2.86 µA µM-1cm-2. This work further provides valuable physical insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures for the rational design of sensing interface.
li et al
A green protocol for construction of C−Se bonds from ketene dithioacetals and diselenides through direct electrochemical oxidative cross-coupling has been developed. This reaction was carried out in an undivided cell system with NaBF4 as the electrolyte and CH3CN as the solvent through galvanostatic electrolysis. A series of substituted ketene dithioacetals and diselenides were tolerant and the desired tetrasubstituted alkenyl selenides were obtained in moderate to excellent yields. In addition, construction of C−S bond from ketene dithioacetals and disulfides through electrochemical method in the presence of KI was also successfully realized. It exhibited high efficiency and broad functional group tolerance.
Dutta et al
Selectivity and sensitivity are the two key parameters for construction of a sensor. In this work, a novel electrochemical sensor based on molecularly-imprinted composites synthesized from o-phenylenediamine (o-PD) and multiwalled carbon nanotube (MWCNT) to detect triclosan is reported. Two different sensors were developed MIC/GC and MIC/cf-MWCNT/GC. To fabricate MIC/GC, molecularly imprinted composite (MIC) was synthesized by cyclic voltammetry using o-PD, COOH-functionalized MWCNT (cf-MWCNT) and triclosan on glassy carbon (GC) electrode, following removal of surface triclosan. MIC/cf-MWCNT/GC was fabricated by synthesizing MIC on cf-MWCNT coated GC. Template removal was performed using NaOH solution. MIC/GC could detect triclosan till 40 ppb while using MIC/cf-MWCNT/GC, 10 ppb of limit of detection (LOD) was achieved. Adsorption isotherms were constructed for both the films. Langmuir adsorption isotherm gave the best fit for MIC/cf-MWCNT/GC with -ΔGads value of 54.952 kJ/mol indicating stronger chemisorption. To understand the role of cf-MWCNT in detection of triclosan, electrochemical band gap studies, electrochemical impedance spectroscopy, and cyclic voltammetry studies were conducted. Both sensors were found to be efficient for detection of triclosan in the presence of interfering ions.
Lakra et al
Cuprous oxide (Cu2O) thin films, antithetically exhibiting n-type conductivity, were electro–deposited on Fluorine-doped Tin Oxide (FTO) coated glass substrates. Linear sweep voltammetry, chronoamperometry, and chronopotentiometry studies coupled with structural characterization of the deposit identify the occurrence of multiple reduction reactions, including the “corrosion” of Cu2O to Cu. Interestingly, under–potential conversion (negative of +0.039 V vs. Ag/AgCl) of the Cu2O film to Cu islands is observed during potentiostatic deposition. The same process is also evinced as a potential spike in the chronopotentiometry curves, during galvanostatic deposition, at current densities that are cathodic of −0.2 mA cm−2. The reason for Cu formation is attributed to the decrease in local pH in the vicinity of the working electrode, whence thermodynamic conditions favor the formation of Cu. Proroguing the Cu formation is achieved by continuous stirring of the solution; deferment to increasingly longer times is observed with increasing stirring rates. Mott-Schottky analysis of the phase pure films reveals the formation of degenerately doped (n ∼ 1020 cm−3) n-type Cu2O.
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Matthew James Newman and Vicky Doan-Nguyen 2024 J. Electrochem. Soc.
Free-standing conducting polymer films, polypyrrole doped with dodecylbenzene sulfonate, were obtained with electrochemical delamination by using redox cycling to delaminate electropolymerized film from the substrate. The use of electrochemical delamination to obtain thinner films than mechanical peeling and the effect of different electropolymerization substrates was investigated. The free-standing films were characterized with electrochemical filling efficiency and scanning electron microscopy. Electrochemical delamination allowed thin free-standing films <10 μm and <1 μm thick to be obtained from 304 stainless steel and gold substrates, respectively. The thinnest films obtainable from 304 stainless steel were limited by the electropolymerization charge density needed for complete film growth and not by electrochemical delamination. The filling efficiency of the films did not appear to be decreased by electrochemical delamination. These findings show the utility of electrochemical delamination to obtain thin free-standing films that also have the benefits of electropolymerization.
Lilian Danielle de Moura Torquato et al 2024 J. Electrochem. Soc.
The development of bioelectrochemical systems requires careful selection of both their biotic and abiotic components to obtain sustainable devices. Herein, we report a biophotoelectrode obtained with polyhydroxybutyrate (PHB), a biopolymer, which purple non-sulphur bacteria produce as an energy stock under specific environmental conditions. The electrode was obtained by casting a mixture composed of PHB and carbon fibers in a 3:2 mass ratio. Following, the composite material was modified with polydopamine and thermally treated to obtain a hydrophilic electrode with improved electrochemical behavior. The bio-based electrode was tested with metabolically active cells of Rhodobacter capsulatus embedded in a biohybrid matrix of polydopamine. The system achieved enhanced catalytic activity under illumination, with an 18-fold increase in photocurrent production compared to biophotoelectrodes based on glassy carbon, reaching a current density of 12 ± 3 µA cm-2, after 30 min of light exposure at +0.32 V. The presented biocompatible electrode provides a sustainable alternative to metal-based and critical raw material-based electrodes for bioelectrochemical systems.
Shufang Shi et al 2024 J. Electrochem. Soc. 171 046504
The hydrogen peroxide oxidation reaction (HPOR) plays a vital role in the emerging H2-H2O2 cycle energy storage system, in which the rational design of HPOR electrocatalyst is essential for achieving high system efficiency. Herein, we establish the HPOR activity trends using structurally well-defined metal phthalocyanines (MPc) as model catalysts via a combined experimental and computational approach. The measured activity sequence follows the order of CoPc > FePc > MnPc > ZnPc > H2Pc > NiPc > CuPc based on their site-normalized exchange current (i0-s). Theoretical calculations indicate that the binding free energy of hydroperoxyl intermediate, HOO*, on MPc (ΔGHOO*) is the activity descriptor for HPOR. A volcano-type activity trend is observed by correlating the logarithm of i0-s (logi0-s) with the ΔGHOO* values and agrees with the theoretical predictions. This HPOR activity trend provides insights into the design of highly active electrocatalysts for HPOR and related energy applications.
Kai Jiao et al 2024 J. Electrochem. Soc. 171 040529
K-ion batteries (KIBs) that use ionic liquid (IL) electrolytes are promising candidates for post-Li-ion batteries because of the abundance of potassium resources and safety of ILs. We successfully synthesized stoichiometric KFeO2 using a solid-state method and evaluated its charge–discharge performance as a KIB positive electrode material, with an amide-based IL electrolyte at 298 K. Transmission electron microscopy, X-ray photoelectron spectroscopy, synchrotron soft X-ray absorption spectroscopy, and energy-dispersive X-ray spectroscopy data showed that the bulk redox and surface oxidation of oxygen, rather than those of iron, contribute to the reversible and irreversible capacities, respectively. Capacity decay occurred upon repeated cycling, owing to the surface irreversible oxidation of oxygen ions to form O2 and K1−xFeO2−x/2, which blocks the pathways of K+ transfer to KFeO2 particles. This study provides a vital platform for constructing novel KIBs and elucidates the important role of oxygen in KFeO2 positive electrode.
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.
Rhodri E. Owen et al 2024 J. Electrochem. Soc. 171 040525
Lithium-ion batteries (LIBs) play an integral role in powering various applications, from consumer electronics to stationary storage, and notably in the accelerating domain of electric vehicles (EVs). Despite their widespread adoption and numerous benefits, safety issues are of major concern, especially with the surge in their utilization and increasing proliferation of second-life cells, particularly in domestic energy storage applications. A critical concern revolves around susceptibility to thermal runaway, leading to highly hazardous and challenging-to-contain fires. Addressing these concerns necessitates effective methods to monitor internal temperature dynamics within lithium-ion cells swiftly and cost-effectively, alongside a need to develop prognostic techniques to pre-empt thermal runaway occurrences. This study presents an innovative approach that uses ultrasound analysis to track intricate internal temperature fluctuations and gradients within cells. Moreover, an efficient multi-stage warning system is proposed that is designed to proactively prevent thermal runaway events. The findings offer promising avenues for enhancing the safety and reliability of lithium-ion battery systems.
Chunguang Li et al 2024 J. Electrochem. Soc. 171 047513
A one-step hydrothermal method was employed to synthesize a three-dimensional (3D) AgNPs/TiO2/Ti3C2Tx composite. Hydrothermal conditions were used to promote the growth of TiO2 nanorods on the Ti3C2Tx sheet, resulting in the formation of a three-dimensional composite nanomaterial. Glutamic acid served as both a reducing agent and a stabilizer to load Ag nanoparticles (AgNPs) onto the 3D composite nanomaterial. The structure of the composite material provided a large accessible surface area, facilitating the anchoring of Ag NPs. Thrombin aptamers were then linked to Ag NPs through Ag-S bonds, establishing a sensitive and label-free aptasensor for thrombin detection. The proposed aptasensor demonstrated excellent electrochemical performance, with a broad linearity range of 5.0 fM to 500 nM and a relatively low detection limit of 2.0 fM (S/N = 3). These findings indicate the potential of Ag NPs/TiO2/Ti3C2Tx in the development of promising electrochemical biosensors.
Highlights
A one-step hydrothermal method was employed to synthesize a three-dimensional AgNPs/TiO2/Ti3C2Tx composite.
AgNPs/TiO2/Ti3C2Tx composite was utilized for fabrication of the label-free thrombin aptamer sensor.
TiO2 nanorods and AgNPs were grown in vivo on the Ti3C2Tx sheet.
D. Ewald et al 2024 J. Electrochem. Soc. 171 044506
The integrity of metallic interconnectors (MICs) in a solid oxide cell stack is crucial because contact resistances or limitations in gas supply may occur. In this contribution, a Crofer 22 APU® interconnector with a (Mn, Co, Fe)3O4 spinel oxide (MCO) coating and a lanthanum-strontium-manganese-cobalt oxide (LSMC) contact layer at the air side was investigated. The electrochemical behavior was characterized by means of IV-characteristics, impedance spectroscopy and DRT analysis. In particular, the contact losses at the air side were measured with targeted potential probes. With respect to the contact layer mounted in a dried state, the application of a stack-like clamping pressure of showed a significant decrease of the contact resistance. In order to extend an existing zero-dimensional performance model for an electrolyte-supported cell with a Ni/GDC fuel electrode and LSCF air electrode, a method was established to parameterize contact losses at the air electrode. The observed activation energy of the contact losses showed to be independent of the clamping pressure. Additionally, the dependency of the cell´s intrinsic ohmic losses towards the steam partial pressure at the Ni/GDC fuel electrode was quantified and included to the model. Simulation studies were validated with experimental data for technical operating conditions.
Andreas Weber et al 2024 J. Electrochem. Soc. 171 040523
This study identifies the critical aspects of binder distribution and mechanical integrity in aqueously processed LNMO cathodes, employing a comprehensive approach involving surface characterization techniques, adhesion strength testing, and electrochemical characterization. The investigation includes the use of the Washburn and Sessile Drop methods for surface free energy analysis, revealing key insights into the interfacial free energy of adhesion between cathode constituents. The results explain the formation of carbon-binder-domains and their impact on adhesion strength, with a particular focus on the conductive additives’ (CA) surface area. The study demonstrates the effectiveness of reducing CA surface area and employing alternative conductive additives, such as vapor-grown carbon fibers (VGCF), in improving adhesion strength and mitigating capacity fade attributed to delamination during cycling. Furthermore, the research emphasizes the role of heat treatment beyond the melting point of the polyvinylidene fluoride (PVDF) latex binder, showcasing its influence on wetting and enhancing mechanical integrity. The presented methodology provides a valuable tool for predicting and optimizing binder distribution, offering insights into improving the overall performance and reliability of aqueously processed cathodes for advanced lithium-ion batteries.
A. Hagen et al 2024 J. Electrochem. Soc. 171 044505
Solid oxide cells (SOCs) can operate in fuel cell and electrolysis mode. This option allows for production of electricity and heat from a green fuel in fuel cell mode and for storage of electricity as gas or use as fuel in electrolysis mode. Demonstration of reversible SOCs has progressed over the last few years. Increase of lifetime and reduction of costs are major factors for successful commercialization. In metal supported SOCs (MSCs) the thickest layer in the cell, the support layer of a few hundred μm, uses metal instead of Ni/YSZ cermet as in state-of-the-art (SoA) fuel electrode supported cells, thereby enabling a significant cost reduction. The present study investigates SoA Ni/YSZ SOCs and MSCs, fabricated by tape casting, lamination, and screen-printing, in reversible operation at 650 °C in 50/50 steam/hydrogen. In the initial few hundred hours, the degradation rate in electrolysis mode is smaller on a MSC compared to a SoA Ni/YSZ cell, while they are comparable in fuel cell mode. According to electrochemical impedance evaluation, the degradation is due to a simultaneous increase of the serial and polarization resistances in the MSC, while it is mainly due to an increase of the polarization resistance in the SoA cell.