Journal of The Electrochemical Society

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.

This year, the battery industry celebrates the 25^th 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.

Lithium iron phosphate (LFP) battery cells are ubiquitous in electric vehicles and stationary energy storage because they are cheap and have a long lifetime. This work compares LFP/graphite pouch cells undergoing charge-discharge cycles over five state of charge (SOC) windows (0%–25%, 0%–60%, 0%–80%, 0%–100%, and 75%–100%). Cycling LFP cells across a lower average SOC results in less capacity fade than cycling across a higher average SOC, regardless of depth of discharge. The primary capacity fade mechanism is lithium inventory loss due to: lithiated graphite reactivity with electrolyte, which increases incrementally with SOC, and lithium alkoxide species causing iron dissolution and deposition on the negative electrode at high SOC which further accelerates lithium inventory loss. Our results show that even low voltage LFP systems (3.65 V) have a tradeoff between average SOC and lifetime. Operating LFP cells at lower average SOC can extend their lifetime substantially in both EV and grid storage applications.

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), LiNi_xCo_yAl_1−x−yO₂ (NCA), and LiNi_xMn_yCo_1−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.

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.

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-SiO_x 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.

Electrolyte motion in commercial Li-ion batteries has become an important topic as researchers seek to understand patterns of degradation that occur in large-format cells. Recent work has linked the motion of excess electrolyte to Li plating on the anode of large-format cells after repeated fast charging - an effect known as electrolyte motion induced salt inhomogeneity (EMSI). Mapping the distribution and flow patterns of electrolyte in the cell is critical to understanding these phenomena and predicting the patterns of Li plating that can result. In this work, we used time-resolved, synchrotron computed tomography (CT) to directly image the flow of electrolyte in two commercial 18650 cells during cycling, with one cell containing SiOx in the negative electrode and the other containing only graphite. The former cell shows significantly more electrolyte "pumping" during charge and discharge as well as asymmetric redistribution of salt along the jelly roll after hundreds of cycles. The results yield new insights into how electrolyte motion and its effects are influenced by the composition, geometry, and orientation of the cell.

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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 (i_o 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.

Layered LiNi_xMn_yCo_zO₂ (NMC) is a widely used class of cathode materials with LiNi_1/3Mn_1/3Co_1/3O₂ (NMC111) being the most common representative. However, Ni-rich NMCs are more and more in the focus of current research due to their higher specific capacity and energy. In this work we will compare LiNi_1/3Mn_1/3Co_1/3O₂ (NMC111), LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622), and LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) with respect to their cycling stability in NMC-graphite full-cells at different end-of-charge potentials. It will be shown that stable cycling is possible up to 4.4 V for NMC111 and NMC622 and only up to 4.0 V for NMC811. At higher potentials, significant capacity fading was observed, which was traced back to an increase in the polarization of the NMC electrode, contrary to the nearly constant polarization of the graphite electrode. Furthermore, we show that the increase in the polarization occurs when the NMC materials are cycled up to a high-voltage feature in the dq/dV plot, which occurs at ∼4.7 V vs. Li/Li⁺ for NMC111 and NMC622 and at ∼4.3 V vs. Li/Li⁺ for NMC811. For the latter material, this feature corresponds to the H2 → H3 phase transition. Contrary to the common understanding that the electrochemical oxidation of carbonate electrolytes causes the CO₂ and CO evolution at potentials above 4.7 V vs. Li/Li⁺, we believe that the observed CO₂ and CO are mainly due to the chemical reaction of reactive lattice oxygen with the electrolyte. This hypothesis is based on gas analysis using On-line Electrochemical Mass Spectrometry (OEMS), by which we prove that all three materials release oxygen from the particle surface and that the oxygen evolution coincides with the onset of CO₂ and CO evolution. Interestingly, the onsets of oxygen evolution for the different NMCs correlate well with the high-voltage redox feature at ∼4.7 V vs. Li/Li⁺ for NMC111 and NMC622 as well as at ∼4.3 V vs. Li/Li⁺ for NMC811. To support this hypothesis, we show that no CO₂ or CO is evolved for the LiNi_0.43Mn_1.57O₄ (LNMO) spinel up to 5 V vs. Li/Li⁺, consistent with the absence of oxygen release. Lastly, we demonstrate by the use of ¹³C labeled conductive carbon that it is the electrolyte rather than the conductive carbon which is oxidized by the released lattice oxygen. Taking these findings into consideration, a mechanism is proposed for the reaction of released lattice oxygen with ethylene carbonate yielding CO₂, CO, and H₂O.

As service lifetimes of electric vehicle (EV) and grid storage batteries continually improve, it has become increasingly important to understand how cells perform after extensive cycling. The multifaceted nature of degradation in Li-ion cells can lead to complex behavior that may be difficult for battery management systems or operators to model. Accurate characterization of heavily cycled cells is critical for developing accurate models, especially for cycle-intensive applications like second-life grid storage or vehicle-to-grid charging. In this study, we use operando synchrotron x-ray diffraction (SR-XRD) to characterize a commercially manufactured polycrystalline NMC622 pouch cell that was cycled for more than 2.5 years. Using spatially resolved synchrotron XRD, the complex kinetics and spatially heterogeneous behavior of such cells are mapped and characterized under both near-equilibrium and non-equilibrium conditions. The resulting data is complex and multifaceted, requiring a different approach to analysis and modelling than what has been used in the literature. To show how material selection can impact the extent of degradation, we compare the results from polycrystalline NMC622 cells to an extensively cycled single-crystal NMC532 cell with over 20,000 cycles—equivalent to a total EV traveled distance of approximately 8 million km (5 million miles) over six years.

Molybdenum disulfide (MoS₂) is well-regarded as a viable alternative to Pt-based electrocatalysts, owing to its highly active edge sites, but its implementation is limited by poor electrical conductivity and low proportions of edge sites. In this work, as-prepared porous carbon foam (CF) substrates with integrated MoS₂ were fabricated using a scalable, robust, and controllable batch-method process. The MoS₂ integrated conductive CF composite (MoS₂-CF) materials were additionally enhanced through post-process carbonization and sulfurization. Both molybdenum precursor powder sources used to fabricate the MoS₂-CF composites, MoO₃ and bulk MoS₂ powders, exhibited well-exposed active edge sites with improved photo-response and electrocatalytic activity after post-processing. Most MoS₂-CF electrodes operated at −10 mA cm⁻² per geometric area with magnitude overpotentials (|η|) between 200 and 500 mV in 0.5 M H₂SO₄, and several electrodes reached |η| < 100 mV. The best performing composites, fabricated with MoO₃ precursor powder and carbonized afterward, displayed a concentration averaged |η| of 134 ± 68 mV with a Tafel slope of 74 ± 15 mV dec⁻¹ and photocurrent response of 96 ± 24 nA. Composites produced with MoO₃ powder also displayed an average 40% lower magnitude overpotential and 75% increase in photo-response when compared to bulk MoS₂ precursor electrodes. In addition to electrocatalytic and photo-response studies performed on the 28 as-prepared CF and post-processed MoS₂-CF composites, the electrochemically active surface area of each electrode was estimated to determine active surface areas and roughness factors.

The electrodeposition of Cu₂O, represented by the reaction 2Cu(II) + 2OH⁻ +2e → Cu₂O + H₂O in alkaline baths containing concentrated lactic acid (approximately 3 mol dm⁻³) as ligands, has been widely studied. In a previous study, such baths were found to generate the complexes [Cu(H₋₁L)L]⁻ and [Cu(H₋₁L)₂]²⁻ (where L⁻ = CH₃CH(OH)COO⁻ and H₋₁L⁻ = CH₃CH(O⁻)COO⁻) in a manner dependent on the bath pH in the alkaline region. This work first assessed the stability of these Cu(II)-lactate complexes based on computational chemistry. The formation of these complexes typically requires approximately one day to reach thermodynamic equilibrium, suggesting that other kinetically favorable, metastable complexes may form prior to the equilibrium complexes. Based on titration curves, [CuL₂(HL)]⁰ was identified as the most likely such intermediate and the effect of this complex on deposition orientation was examined. Electrodeposited Cu₂O obtained from a bath not yet at equilibrium with a pH of approximately 9.5 was randomly oriented whereas deposits from an equilibrated bath showed a preferential 〈100〉 orientation. These findings suggest that bath aging is an essential step in achieving reproducible Cu₂O electrodeposition. Additionally, modifying the bath preparation method was found to prevent the formation of metastable complexes.

Cadmium ions (Cd²⁺), as ubiquitous water contaminants, pose severe threats to human health due to their irreversible toxicity even at trace levels. The development of precise quantification methods for aqueous Cd²⁺ is therefore critical for environmental monitoring and public health protection. In this work, cobalt-manganese carbon nanofibers (CoMnCNFs) were synthesized through electrostatic spinning followed by high-temperature carbonization. These CoMnCNFs were integrated with reduced graphene oxide (rGO) to construct an electrochemical sensor using screen-printed electrodes for Cd²⁺ detection in aquatic systems. The sensor's performance was systematically characterized through microscopic techniques (scanning electron microscopy and X-ray photoelectron spectroscopy) and electrochemical analyses (cyclic voltammetry and square-wave voltammetry). Quantitative Cd²⁺ detection demonstrated a linear response range of 0.05–100 μg l⁻¹ with a low detection limit (LOD) of 0.043 μg l⁻¹, outperforming many reported sensors. The sensor also demonstrated good selectivity and stability. By integrating rGO and CoMnCNFs as co-modification materials on portable screen-printed electrodes, this work provides a feasible strategy for on-site detection of cadmium ions in aquatic environments.

The overlapping redox potentials of analytes and the lack of selectivity present significant challenges for unmodified electrodes in electrochemical sensing. In this work, we have fabricated an electrochemical sensor based on cerium oxide nanocubes (CeO₂-NCs) coated glassy carbon electrode (CeO₂-NCs@GCE) for individual and simultaneous detection of dopamine (DA) and acetaminophen (APAP) with high sensitivity and selectivity. The CeO₂-NCs were synthesized using a one-step hydrothermal method and characterized by Transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy. Cyclic voltammetry and electrochemical impedance spectroscopy were employed for electrochemical characterizations. With improved electrocatalytic redox activity due to enhanced active surface area and reduced interfacial charge transfer resistance, CeO₂-NCs@GCE shows superior detection efficiency. The detection of DA and APAP was evaluated using differential pulse voltammetry. Low detection limit values of 0.696 μM for DA and 0.341 μM for APAP with a wide linear range of 10–400 μM applicability were achieved. The CeO₂-NCs@GCE sensor was also used to detect DA in DA injection and APAP in paracetamol tablet samples. The developed sensor demonstrated satisfactory recovery results ranging from 96.5 to 102.8% in pharmaceutical samples, confirming the applicability of the proposed method for simultaneous detection of DA and APAP in real samples.

A chiral drug must stereospecifically bind to the SARS-CoV-2 protein targets (Spike, RdRP, or 3CL protease) to form a stable diastereomeric complex for effective action. Herein, we show the enantioselective binding differences between anti-covid drug atorvastatin (RR-AT and SS-AT) isomers and bovine serum albumin (BSA). RR-AT (strong) and SS-AT (weak) form a 1:1 complex with BSA. Our findings, particularly the strong binding of RR-AT to BSA, hold significant promise for treating COVID-19. Using nitrogen-doped carbon nanofibers (NCNF) and polyvinyl chloride (PVC) with BSA, the device we developed is a step towards more effective and targeted treatments. The enantioselective solid contact ion selective electrode displays a Nernstian slope of 59.70 ± 0.20 mV decade⁻¹ with a linear concentration range extending from 1.0 × 10^–2 to 1.0 × 10^–7 M, and a detection limit of 6.5 ± 0.16 × 10^–8 M for the analysis of the RR-AT isomer. The sensor exhibited promising enantioselective detection of RR-AT in the presence of a large excess of SS-AT (1:99). Moreover, good recovery values, near 98%–102%, were achieved for the analysis of RR-AT in pharmaceutical and biological samples, including blood and urine samples from patients infected with SARS-CoV-2 on AT medication.

Electrolysis serves as an effective technique for metal preparation, with the electrolytic cell being the fundamental apparatus. The design of the electrolytic cell significantly influences the mass transfer process. Therefore, it is crucial to create an appropriate structure for the electrolytic cell to minimize energy consumption during electrolysis. Given the unique characteristics of the metals involved, the configurations of electrolytic cells vary accordingly. This article examines primary metals produced through electrolysis, such as aluminum and alkali metals, and discusses advancements in research and design principles related to electrolytic cell structures. It also compares various types of electrolytic cells and suggests strategies for structural optimization. Additionally, the role of simulation in the design of electrolytic cells is emphasized. Finally, the article addresses the challenges encountered by electrolytic cells in industrial settings and offers recommendations for structural improvements.

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The opioid crisis has emerged as a critical public health issue, characterized by the widespread misuse, addiction, and adverse societal impacts of opioid substances. Addressing this multifaceted crisis demands innovative approaches, and the field of forensic science has increasingly turned to electrochemical methods as a powerful tool in the battle against opioids. Here we provide an overview of the significant role played by electrochemical techniques in the detection, analysis, and monitoring of opioids. By harnessing the capabilities of electrochemical sensors, nanomaterial-based platforms, and microfluidic devices, forensic scientists have achieved breakthroughs in opioid detection, offering higher sensitivity, specificity, and rapidity than traditional methods. We explore the latest advancements and applications of electrochemical techniques in forensic opioid analysis, highlighting their potential to revolutionize not only the investigative process but also the management of opioid-related crises. With an emphasis on real-time, on-site, and non-invasive detection, we underscore the importance of electrochemical techniques as a vital component in combating the opioid epidemic and contributing to public safety and well-being.

For many years since Gurney introduced quantum mechanics to electrochemistry, models and calculations assumed bonding and other properties at the electrochemical interface may be calculated with adequate accuracy at the potential of zero charge (PZC) and that the effect of potential lies solely in controlling the energy of the electron involved in the transfer, which comes from or goes to an external energy level. The energy of the electron is assigned to the Fermi energy, E_f, of the electrode for the particular potential being modeled. This is done in the Butler-Volmer theory as well as in several quantum mechanical modeling procedures that are introduced here. Though the PZC in fact changes as the identity, amount, and structures of molecules chemically bonded to the electrode are varied during calculations using these models, there is no control of the electrode potential in the calculations. The past two decades have seen the development of computer codes that can incorporate controlled incremental surface charging with polarizable electrolyte models that compensate it, resulting in zero net interface charge. Calculations using these codes provide accurate predictions of the potential-dependent energies of reactants and products, reversible potentials, and electron transfer activation energies.

Due to the advantages of environmental friendliness and high energy density, fuel cells have broad application prospects in many fields, such as automobiles, ships, aerospace, etc However, commercial applications of fuel cells also face challenges of durability and reliability, especially in shock and vibration environments. Here, the electrochemical and mechanical behaviours of fuel cells under vibration environments are described, and the effects of vibration and shock conditions on the electrochemical, mechanical, water and gas transport, and durability performance of fuel cells are systematically reviewed, involving the variation laws of assembly torque, sealing, relative slippage between cells, water and gas transport, electrical resistance, and membrane electrodes. In addition, the methods that can mitigate the effects of vibration on fuel cells in existing studies are summarised. Finally, discussions and perspectives on the research methods of fuel cell performance under vibration are presented. It is hoped that the review can provide a systematic comprehension and direction for vibration protection of fuel cells.

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Highlights

• Vibration and shock have a negative impact on fuel cell performance in most cases.

• Fuel cell performance degradation is affected by the coupling of multiple phenomena.

• Specific vibration levels improve cell performance by facilitating water management.

• Monitoring and vibration isolation/damping enable vibration protection of fuel cells.

Renewable energy systems will need large-scale energy storage to ensure reliability and provide power when and where it is needed. Even though lithium-ion batteries are increasingly used for large-scale storage, their costs and competition in terms of materials needed for electric vehicles are driving the need for alternative batteries for stationary energy storage systems. Molten sodium-ion batteries that operate at intermediate temperatures, approximately 150 °C or less, offer an abundant and cost-effective solution to our energy storage issues. This review paper highlights the materials, enhancements, and performance of molten Na–ion batteries that operate at temperatures at or below 150 °C for use in energy storage systems as well as an outlook on future improvements for this energy storage system.

This study explores chloride molten salt electrolysis (CMSE) as a promising route for energy-efficient iron metal (Fe) production. Moderate temperature (500 °C) LiCl-KCl molten salts offer excellent thermodynamic stability, high ionic conductivity and diffusivity, and high solubility for FeCl₃, thereby enabling efficient Fe metal extraction at high electrowinning rates. Here, we demonstrate the two essential steps for converting taconite ore into Fe metal. First, Fe₂O₃ from taconite pellets was selectively leached in HCl yielding a high-purity FeCl₃ aqueous solution, while the gangue components settled at the bottom. Then, anhydrous FeCl₃ was electrolyzed in a LiCl-KCl eutectic molten salt at 500 °C at high current density (1 A cm⁻²) and at high Coulombic efficiency (>85%). Analysis of the electrowon Fe deposits revealed dendritic structures with purity of >99 wt%, which could be further improved to nearly 100 wt% through arc re-melting. CMSE offers low specific energy consumption (3.7 kWhr kg⁻¹), competitive with H₂-DRI and other electrolytic approaches being pursued globally. Our findings underscore the potential of CMSE as an energy-efficient route for electrosynthesis of Fe metal.

Cathode-electrolyte interphase (CEI) is critical for inhibiting the cathode degradation to maintain cell life. However, the evolution of the CEI is still unclear due to its complex and slow dynamic process. Here we used scanning electrochemical microscopy (SECM) for in situ investigation of CEI formation process on LiFePO₄ cathode. Feedback images and probe scan curves showed a heterogeneous passivation that was gently generated on the LiFePO₄ particles during both charging and discharging. Besides, a LiFePO₄ composited electrode was also used to investigate the CEI formation to simulate the condition of real battery system. The composited cathode does not show obvious CEI formation within first two cycles. The SECM results between the pristine LiFePO₄ particles and the composited LiFePO₄ indicated the dynamic accumulation of CEI, which is influenced by the ability to charge transfer kinetics of cathode materials. This approach provided a feasible consideration for the connections between the dynamic evolution of the CEI and changes in charge transfer capability of cathode during cycling.

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Highlights

• In-situ investigation of cathode-electrolyte interphase formation.

• The evolution of native active material and composite slurry were compared.

• The electrochemical activity change upon cathode cycling are analysed in situ.

• The influence of the charge transfer capability upon CEI generation is revealed.

We revisit the classical derivation of the Butler-Volmer equation to include the effect of the electrode metal. If the metal is replaced by one with a different work function, keeping other conditions in the electrode constant, the chemical potential of electrons ${\mu }_{e}$ and the Galvani potential $\varphi$ change in a complementary manner. Changes in ${\mu }_{e}$ and $\varphi$ each impact the free energies of activation of the forward and backward electron transfer reactions, so we modify the classical expressions which relate them to applied voltage E by including also the effect of ${\mu }_{e}.$ Inserting these expressions in an Eyring-Polyani or Arrhenius type equation in the traditional way, we obtain a modified Butler-Volmer equation which expresses current density as a function of both $E$ and ${\rm{\Delta }}{\mu }_{e}.$ The exchange current density ${j}_{0}$ appears as an exponential function of ${\rm{\Delta }}{\mu }_{e}.$ For the work function ${\rm{\Phi }}$ of the metal, the approximation ${\rm{\Delta }}{\mu }_{e}\approx -F{\rm{\Delta }}{\rm{\Phi }}$ yields a linear relationship between $\mathrm{ln}{j}_{0}$ and ${\rm{\Phi }}.$ The linear increase in $\mathrm{ln}{j}_{0}$ with ${\rm{\Phi }}$ has long been reported. We show two experimental examples: the aqueous Fe²⁺/Fe³⁺ couple with positive slope and the hydrogen evolution reaction (HER) with parallel lines for the d and sp metals, both with positive slopes.

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The kinetics of composite cathodes for solid-state batteries (SSBs) relies heavily on their microstructure. Spatial distribution of the different phases, porosity, interface areas, and tortuosity factors are important descriptors that need accurate quantification for models to predict the electrochemistry and mechanics of SSBs. In this study, high-resolution focused ion beam-scanning electron microscopy tomography was used to investigate the microstructure of cathodes composed of a nickel-rich cathode active material (NCM) and a thiophosphate-based inorganic solid electrolyte (ISE). The influence of the ISE particle size on the microstructure of the cathode was visualized by 3D reconstruction and charge transport simulation. By comparison of experimentally determined and simulated conductivities of composite cathodes with different ISE particle sizes, the electrode charge transport kinetics is evaluated. Porosity is shown to have a major influence on the cell kinetics and the evaluation of the active mass of electrochemically active particles reveals a higher fraction of connected NCM particles in electrode composites utilizing smaller ISE particles. The results highlight the importance of homogeneous and optimized microstructures for high performance SSBs, securing fast ion and electron transport.

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.

Solid oxide fuel cells (SOFCs) are becoming increasingly important due to their high electrical efficiency, the flexible choice of fuels and relatively low emissions of pollutants. However, the increasingly growing demands for electrochemical devices require further performance improvements as for example by reducing degradation effects. Since it is well known that the 3D electrode morphology, which is significantly influenced by the underlying manufacturing process, has a profound impact on the resulting performance, a deeper understanding for the structural changes caused by modifications of the manufacturing process or degradation phenomena is desirable. In the present paper, we investigate the influence of the annealing time and the operating temperature on the 3D morphology of SOFC anodes using 3D image data obtained by focused-ion beam scanning electron microscopy, which is segmented into gadolinium-doped ceria, nickel and pore space. In addition, structural differences caused by manufacturing the anode via infiltration or powder technology, respectively, are analyzed quantitatively by means of various geometrical descriptors such as specific surface area, mean geodesic tortuosity, and constrictivity. The computation of these descriptors from 3D image data is carried out both globally as well as locally to quantify the heterogeneity of the anode structure.

The demand for a strong discharge capacity in lithium-ion batteries is increasing. However, there are few models and correlation analysis for special lithium-ion batteries with ultra-high discharge capacity in the existing research, and the existing conventional discharge rate model prediction is not satisfactory. Based on the single particle theory, a simplified lumped semi-empirical model containing multiple classes of overpotential and heat generation terms was established. The lithium-ion battery with high discharge rate capability was tested at large currents. The reliability and accuracy of the model were verified. The root mean square errors for the discharge current and temperature were respectively less than 30 mV and 2.8°C at discharge rates above 30C. The maximum relative error of the voltage was only 2.4%, which was the highest level of prediction accuracy known to the authors. Based on the model, the contribution from the various heat generation sources during the discharge process was analyzed. This model could be easily applied to the analysis and design of battery modules without the detailed information of cell materials.

To enhance the accuracy of lithium-ion battery state-of-charge (SOC) prediction, this study develops an improved deep learning model optimized by the novel improved dung beetle optimizer (NIDBO). The NIDBO algorithm is derived from traditional dung beetle optimizer by introducing an optimal value guidance strategy and a reverse learning strategy. The deep learning model integrates convolutional neural networks (CNN), bidirectional gated recurrent units (BIGRU), and a self-attention mechanism to form the CNN-BIGRU-SA model. Subsequently, the NIDBO algorithm is employed to optimize the hyperparameters of the model, aiming to improve prediction performance. Discharge data from ternary lithium batteries and lithium iron phosphate batteries were collected. Each type of battery was subjected to 12 operating conditions, totaling 24 sets of battery operating condition data, which were used to test and validate the effectiveness of the model. The results demonstrate that the proposed model exhibits exceptional accuracy in SOC prediction, offering significant advantages over traditional methods and unoptimized models. At the same time, the model was tested under dynamic stress test and federal urban driving schedule conditions. Additionally, the generalization capability of the model is verified by cross-validating the discharge data of the two types of batteries.

Due to the continuous increase in demand for electric vehicles which run on lithium-ion batteries, the need to improve their performance is also increasing. As a result, optimizing each manufacturing stage is critical, out of which calendering is a final stage of electrode production in which electrodes are compressed while passing through a stack of hard/soft bowls, leading to changes in the electrode’s porosity, thickness, density, smoothness, adhesion/bonding strength, wettability, and coating homogeneity. Calendered electrodes enhance volumetric energy density, rate capability, cyclic rate, and life span of the batteries. Hard/soft bowls used in a calendering machine have a covering/layering of either chilled cast iron or fragile material (nylon, cotton, or rubber) with varying thickness. Here we report on an investigation of the influence of cover thickness along with other design and process parameters of machine calender namely bowl diameter, bulk modulus and line load on the contact width with the help of a generalized nip mechanics model. Additionally, the influence of bowl temperature and contact time on the electrode sheet was investigated with the help of heat transfer model.

This study systematically investigated the correlation between electrolyte decomposition products and overcharging voltages in cylindrical acetonitrile-based supercapacitors. Using a combination of gas chromatography-mass spectrometry, nuclear magnetic resonance, and thermogravimetric analyses, we identified acetamide as a primary degradation marker, forming at voltages as low as 2.7 V and reaching peak concentration at 3.5 V before undergoing further transformation into N-ethyl acetamide and trimethylsilyl acetamide. Notably, at ≥3.9 V, trimethylsilyl acetamide becomes the dominant by-product due to interactions with silicon impurities in activated carbon electrodes, accelerating degradation mechanisms. These decomposition pathways significantly impair supercapacitor performance, leading to a reduction in capacitance, coulombic efficiency, and energy efficiency by diminishing the effective surface area of the electrode. Furthermore, trace water generated at elevated voltages exacerbates these degradation reactions, further compromising stability. This work underscores the critical role of electrolyte purity and electrode material composition in mitigating performance deterioration. The findings provide fundamental insights into voltage-dependent degradation mechanisms, offering strategies to enhance the longevity, efficiency, and reliability of acetonitrile-based supercapacitors for high-power energy storage applications.

Molybdenum disulfide (MoS₂) is well-regarded as a viable alternative to Pt-based electrocatalysts, owing to its highly active edge sites, but its implementation is limited by poor electrical conductivity and low proportions of edge sites. In this work, as-prepared porous carbon foam (CF) substrates with integrated MoS₂ were fabricated using a scalable, robust, and controllable batch-method process. The MoS₂ integrated conductive CF composite (MoS₂-CF) materials were additionally enhanced through post-process carbonization and sulfurization. Both molybdenum precursor powder sources used to fabricate the MoS₂-CF composites, MoO₃ and bulk MoS₂ powders, exhibited well-exposed active edge sites with improved photo-response and electrocatalytic activity after post-processing. Most MoS₂-CF electrodes operated at −10 mA cm⁻² per geometric area with magnitude overpotentials (|η|) between 200 and 500 mV in 0.5 M H₂SO₄, and several electrodes reached |η| < 100 mV. The best performing composites, fabricated with MoO₃ precursor powder and carbonized afterward, displayed a concentration averaged |η| of 134 ± 68 mV with a Tafel slope of 74 ± 15 mV dec⁻¹ and photocurrent response of 96 ± 24 nA. Composites produced with MoO₃ powder also displayed an average 40% lower magnitude overpotential and 75% increase in photo-response when compared to bulk MoS₂ precursor electrodes. In addition to electrocatalytic and photo-response studies performed on the 28 as-prepared CF and post-processed MoS₂-CF composites, the electrochemically active surface area of each electrode was estimated to determine active surface areas and roughness factors.

The electrodeposition of Cu₂O, represented by the reaction 2Cu(II) + 2OH⁻ +2e → Cu₂O + H₂O in alkaline baths containing concentrated lactic acid (approximately 3 mol dm⁻³) as ligands, has been widely studied. In a previous study, such baths were found to generate the complexes [Cu(H₋₁L)L]⁻ and [Cu(H₋₁L)₂]²⁻ (where L⁻ = CH₃CH(OH)COO⁻ and H₋₁L⁻ = CH₃CH(O⁻)COO⁻) in a manner dependent on the bath pH in the alkaline region. This work first assessed the stability of these Cu(II)-lactate complexes based on computational chemistry. The formation of these complexes typically requires approximately one day to reach thermodynamic equilibrium, suggesting that other kinetically favorable, metastable complexes may form prior to the equilibrium complexes. Based on titration curves, [CuL₂(HL)]⁰ was identified as the most likely such intermediate and the effect of this complex on deposition orientation was examined. Electrodeposited Cu₂O obtained from a bath not yet at equilibrium with a pH of approximately 9.5 was randomly oriented whereas deposits from an equilibrated bath showed a preferential 〈100〉 orientation. These findings suggest that bath aging is an essential step in achieving reproducible Cu₂O electrodeposition. Additionally, modifying the bath preparation method was found to prevent the formation of metastable complexes.

A chiral drug must stereospecifically bind to the SARS-CoV-2 protein targets (Spike, RdRP, or 3CL protease) to form a stable diastereomeric complex for effective action. Herein, we show the enantioselective binding differences between anti-covid drug atorvastatin (RR-AT and SS-AT) isomers and bovine serum albumin (BSA). RR-AT (strong) and SS-AT (weak) form a 1:1 complex with BSA. Our findings, particularly the strong binding of RR-AT to BSA, hold significant promise for treating COVID-19. Using nitrogen-doped carbon nanofibers (NCNF) and polyvinyl chloride (PVC) with BSA, the device we developed is a step towards more effective and targeted treatments. The enantioselective solid contact ion selective electrode displays a Nernstian slope of 59.70 ± 0.20 mV decade⁻¹ with a linear concentration range extending from 1.0 × 10^–2 to 1.0 × 10^–7 M, and a detection limit of 6.5 ± 0.16 × 10^–8 M for the analysis of the RR-AT isomer. The sensor exhibited promising enantioselective detection of RR-AT in the presence of a large excess of SS-AT (1:99). Moreover, good recovery values, near 98%–102%, were achieved for the analysis of RR-AT in pharmaceutical and biological samples, including blood and urine samples from patients infected with SARS-CoV-2 on AT medication.

Solid oxide fuel cells (SOFCs) are becoming increasingly important due to their high electrical efficiency, the flexible choice of fuels and relatively low emissions of pollutants. However, the increasingly growing demands for electrochemical devices require further performance improvements as for example by reducing degradation effects. Since it is well known that the 3D electrode morphology, which is significantly influenced by the underlying manufacturing process, has a profound impact on the resulting performance, a deeper understanding for the structural changes caused by modifications of the manufacturing process or degradation phenomena is desirable. In the present paper, we investigate the influence of the annealing time and the operating temperature on the 3D morphology of SOFC anodes using 3D image data obtained by focused-ion beam scanning electron microscopy, which is segmented into gadolinium-doped ceria, nickel and pore space. In addition, structural differences caused by manufacturing the anode via infiltration or powder technology, respectively, are analyzed quantitatively by means of various geometrical descriptors such as specific surface area, mean geodesic tortuosity, and constrictivity. The computation of these descriptors from 3D image data is carried out both globally as well as locally to quantify the heterogeneity of the anode structure.

We studied Zn passivation and oxide growth in Zincate (Zn(OH)42-) in 4 and 8 M KOH solutions using an electrochemical quartz crystal microbalance (EQCM), building on our initial work at 1M KOH where passivation was kinetically controlled. A porous passivating oxide spontaneously forms on Zn electrodes when KOH is above 4 M and saturated with zincate. However, passivation does not occur when bulk zincate concentration is decreased, resulting in continual Zn dissolution. EQCM data suggests that the passivation mechanism is strongly affected by pOH. Mass transport and kinetic processes in the 4M KOH electrolytes couple and govern Zn passivation. At 8M, KOH concentration shifts passivation to mass transport control. We explain this by the increased solubility of Zn(OH)3‑ with increasing pOH. The variation in the mechanism of passivation implications for how passivation is handled in Zn-alkaline batteries. The importance of controlling the mass transport increases with increased pOH, suggesting that electrode design, additives, and potential flow should be optimized. At lower pOHs, kinetics and mass transport must be balanced to manage passivation effectively. Additionally, the changing nature of the native oxide layer on the surface has implications for the evenness of deposition and dissolution on the Zn electrode.

To improve mass transport limitations in proton exchange membrane fuel cells (PEMFCs), a detailed analysis of the gas diffusion layer structure can aid to understand the transport processes of oxygen to the catalyst layer and the liquid water removal mechanism. Herein, the effect of tortuosity was studied using two different microporous layer (MPL) structures and their hydrophobic and hydrophilic clones. Focused ion beam—scanning electron microscopy tomography showed that all structures had similar porosity but different characteristic pore diameters. Volumetric analysis using the Laplace solver TauFactor and the PuMA random walk method yielded a tortuosity of 1.2–1.3 for both MPLs, and these values were confirmed by experiments based on limiting current measurements in a single-cell PEMFC. The inclusion of Knudsen diffusion in the MPL proved to be essential for both methods. Subsequent analysis using experimental operating conditions that induce liquid water formation suggested that different water filling mechanisms occur in MPLs with different surface wettability. A mechanistic understanding of the water filling processes was investigated by simulations, considering the effect of liquid water saturation in different pore size domains. It was found that the tortuosity increases more drastically when narrow pores are blocked by liquid water, consistent with the experiments.

The dynamic charge acceptance (DCA) of negative pastes in lead acid batteries is studied using a continuum level model that is validated against in situ X-ray diffraction experiments. The model matches the current transient during a ten-minute, 2.4 V charge at 80% state of charge (SOC) using a distribution of PbSO₄ particles. <2% by volume of small, reactive particles is shown to provide ∼50% of the capacity during the first ten seconds. Increases in DCA with increasing carbon content are captured with increasing lead surface area. The increase in DCA when the 2.4 V charge is done after discharging to 80% SOC (vs charging to 80%) is captured by reducing the PbSO₄ particle sizes. It is hypothesized that the lower DCA after charging is caused by the absence of smaller particles that were consumed during the initial charge to 80% SOC, which is confirmed from X-ray measurements. Finally, two-particle case studies show that reducing the PbSO₄ particle size is more effective for increasing DCA than increasing the PbSO₄ dissolution rate alone. For a given lead surface area, the optimal DCA occurs when the particle sizes are large enough to avoid blocking the surface but small enough to provide dissolution/diffusion improvements.

In the industrial manufacturing process of zinc electrowinning, picking out or fabricating the appropriate anode material plays a vital role in diminishing the overpotential of oxygen evolution at the anode, thus reducing energy consumption. The research suggests that an α-PbO₂ transition layer with strong binding ability and high conductivity should be epitaxially grown on the Pb-0.6%Sb alloy substrate. This can effectively prevent the passivation of the substrate. Subsequently, a β-PbO₂ deposition surface layer doped with Co²⁺ and MoS₂ will be prepared to further tackle the problems of substrate passivation and low anodic electrocatalytic activity. As a result, a novel Pb-0.6%Sb/α-PbO₂/β-PbO₂-Co-Mo composite anode can be formed. Through testing, it is revealed that the composite anode exhibits a low oxygen evolution overpotential of 586 mV and a low charge transfer resistance of 0.483 Ω. Moreover, it shows a current efficiency of 91.2% at a high current density of 500 A·m⁻². Additionally, the energy consumption for generating one-ton of cathodic zinc is calculated to be 2322.8 kW·h. Hence, this research offers strategies for the study of energy consumption in zinc electrowinning and other relevant applications.

This paper develops a model to predict and interpret the performance of an elevated-temperature, electrochemical, membrane-assisted, water-gas- shift process. The process uses separated feed streams of H2O and CO to pro- duce separated streams of H2 and CO2, without an external electrical power source. The dense ceramic membrane is mixed ionic-electronic-conducting (MIEC) gadolinium-doped ceria (GDC) and the porous composite electrodes are Ni-YSZ. At elevated temperature, GDC conducts both oxygen ions and small polarons. The present process uses chemical potential to drive the pro- cess. Electrochemical oxidation of CO proceeds within the composite anode and H2O reduction proceeds within the composite cathode. At high tem- perature (e.g., T > 700 ◦C), GDC has significant electronic leakage in the form of a reduced-cerium small polaron, which supports the charge-transfer reactions. In a typical electrolyzer or fuel cell, this leakage is significantly problematic. However, the present process depends on the leakage current to complete the electrochemical circuit. Model development and validation is based on measured material properties and reactor performance. Potential applications include using CO-rich blast-furnace off gases in steel processing, producing separated streams of H2 and CO2.

Our goals were to investigate the growth and electron consumption of Geobacter sulfurreducens in bioelectrochemical systems with advective electrodes with excess surface area, determine the role of the counter electrode on the estimated Faradaic efficiencies based on the electron donor consumptions, and propose two separate mathematical models to predict both current development prior to steady-state current, and biomass growth afterward. Excess surface area and concentrated inocula with advection resulted in current development curves which reached a limiting current plateau within several hours and could be predicted with a current-development model. After steady-state current, the biomass continued to accumulate while acetate concentration decreased linearly over time. A futile feedback loop of hydrogen production and consumption scaled with current. Finally, an arithmetic growth model describing biomass development during steady-state current was proposed.