The widespread reliance on evaluating electrocatalysts in electrochemical half-cells presents limitations that hinder a faster transition from academia to industry and can lead to premature exclusion of promising materials. To address these challenges, it is crucial to implement materials testing in application-relevant setups such as zero-gap full-cells. This transition can be achieved through implementing coherent workflows combining rapid evaluation of as-synthesized materials, electrode evaluation at different scales, and post-mortem analysis. This work presents a comparative study of three spray-flame synthesized lanthanum-based perovskite materials (LaMnO3, LaFeO3, and LaCoO3) for the oxygen evolution reaction under alkaline conditions, highlighting different behavior across scales. The research demonstrates how the interplay of materials properties, electrode engineering, and metal-support interactions influences performance under mild and harsh electrochemical conditions. Electrochemical half-cell testing consistently identifies LaFeO3 as the best oxygen evolution reaction catalyst across various configurations. This unforeseen behavior necessitates further investigation under application-relevant conditions. Full-cell testing at 500 mA cm-2 corroborates the trends observed in electrochemical half-cell testing, with LaFeO3 and LaMnO3 exhibiting comparable performance to LaCoO3 after prolonged operation. Furthermore, a degradation study under 1000 mA cm-2 highlights their potential for continued catalyst development. Advanced post-mortem techniques provide deeper insight into catalytic activity and structural changes, linking performance evolution to catalyst-substrate interactions and material-dependent surface changes under oxidative polarization. By bridging fundamental studies to application-relevant testing, this research provides knowledge and methods for accelerated material and electrode development.

Currently, several competing computational frameworks, including free, open-source, and commercial packages exist, that enable users to perform purely electrochemical simulations based on the Doyle-Fuller-Newman (DFN) model or simulations additionally coupled with thermal/mechanical physics. In this paper, the performance of several numerical software packages is reviewed and evaluated based on the ease of model setup, spatial dimension capability, and model accuracy. In the absence of standardized benchmark tests, a series of discharge simulations under various operating conditions, such as static and dynamic electric vehicle driving cycle loads, as well as galvanostatic intermittent titration techniques (GITTs), provide rigorous test methods to evaluate and benchmark battery modeling software packages. Two different lithium-ion battery (LIB) parameter sets enable complete assessment of the software packages in terms of accuracy, validity, and solver sensitivity. The careful selection of actual operating condition simulations and independent evaluation tests serves as a benchmark for LIB electrochemical simulation packages and can help users of these packages develop their analyses with confidence in the validity of their results. It is hoped that this paper will serve as a reference for new and established researchers and simulation engineers in LIB simulation to gain knowledge about the capabilities of existing lithium-ion simulation packages.

Lithium-sulfur batteries have a high energy density but lack cycle stability to reach market maturity. This is mainly due to the polysulfide shuttle mechanism, i. e., the leaching of active material from the cathode into the electrolyte and subsequent side reactions. We demonstrate how to attenuate the polysulfide shuttle by magnetron sputtering molybdenum oxysulfide, manganese oxide, and chromium oxide onto microporous polypropylene separators. The morphology of the amorphous coatings was analyzed by SEM and XRD. Electrochemical cyclization quantified how these coatings improved Coulombic efficiency and cycle stability. These tests were conducted in half cells. We compare the different performances of the different coatings with the known chemical and adsorption properties of the respective coating materials.

Abstract Due to the fluctuating feed-in of renewable energies, controllable power plants such as highly efficient CHP plants (combined heat and power) will continue to be required to cover the residual load. Gas engines and turbines currently dominate the natural gas-based CHP market due to their low investment costs and acceptable electrical efficiency. In the event of a future fuel switch due to the energy transition from natural gas to hydrogen, fuel cell systems are becoming increasingly important due to their very high efficiency and improved dynamics in hydrogen operation and can therefore represent an alternative to gas engines and turbines. In addition to a possible fuel switch, good dynamic and full heat utilization represents an additional challenge for CHP systems. Therefore, this study aims to investigate the influence of a fuel switch from natural gas to hydrogen on the operation of a fuel cell (PAFC) in terms of efficiency, heat utilization and dynamics. It was shown that the electrical efficiency of the hydrogen-operated PAFC is significantly higher than in natural gas operation due to the omitted reformer and the associated reformer losses. In hydrogen operation, there is also no limitation of the dynamics by the reformer. Furthermore, in hydrogen operation there is a more favorable ratio of high-temperature to low-temperature heat, which facilitates the use of heat. Detailed and validated simulation models in Aspen Plus are used as the basis for this investigation.

We present a detailed analysis of the behavior of a new zinc-air flow cell. This system offers several unique insights into the zinc electrochemistry. Due to the constant slurry flow, concentration gradients are completely destroyed every few seconds and therefore negligible and it is possible to take samples from the anode without interrupting the discharge process. To clarify the underlying processes, the potential of the zinc electrode, the zincate concentration (by titration) and the zinc-particles (by SEM) were analyzed. These measurements offer the unique opportunity to distinguish between thermodynamic and kinetic contributions to the cell voltage. We found, that in this system zinc passivation, is caused by a critical zincate concentration and the steep increase of the cell potential is a kinetic effect, caused by partial passivation. The key factor for passivation, which limits the capacity to 82 mAh gzinc-1 or 41 mAh gslurry-1, is the nucleation of ZnO before the critical zincate concentration is reached. This allows capacities of up to 420 mAh gzinc-1 or 210 mAh gslurry-1. These results are therefore not only essential for a further increase of the practical capacity of the system but also offer unique insights in the zinc electrochemistry. This is the first study which compares measured zincate concentrations in the electrolyte with measured zinc potentials. We find, that in phase a zincate is the dominant oxidation product. Only at low current densities (20 mA cm-2), ZnO precipitation is fast enough to prevent passivation in phase b. The steep increase of the zinc potential is due to kinetic effects (partial passivation decreased active area). image

Despite considerable efforts to develop electrolyzers for energy conversion, progress has been hindered during the implementation stage by different catalyst development requirements in academic and industrial research. Herein, a coherent workflow for the efficient transition of electrocatalysts from basic research to application readiness for the alkaline oxygen evolution reaction is proposed. To demonstrate this research approach, La0.8Sr0.2CoO3 is selected as a catalyst, and its electrocatalytic performance is compared with that of the benchmark material NiFe2O4. The La0.8Sr0.2CoO3 catalyst with the desired dispersity is successfully synthesized by scalable spray-flame synthesis. Subsequently, inks are formulated using different binders (Nafion®, Naf; Sustainion®, Sus), and nickel substrates are spray coated, ensuring a homogeneous catalyst distribution. Extensive electrochemical evaluations, including several scale-bridging techniques, highlight the efficiency of the La0.8Sr0.2CoO3 catalyst. Experiments using the scanning droplet cell (SDC) indicate good lateral homogeneity for La0.8Sr0.2CoO3 electrodes and NiFe2O4-Sus, while the NiFe2O4-Naf film suffers from delamination. Among the various half-cell techniques, SDC proves to be a valuable tool to quickly check whether a catalyst layer is suitable for full-cell-level testing and will be used for the fast-tracking of catalysts in the future. Complementary compression and flow cell experiments provide valuable information on the electrodes’ behavior upon exposure to chemical and mechanical stress. Finally, parameters and conditions simulating industrial settings are applied using a zero-gap cell. Findings from various research fields across different scales obtained based on the developed coherent workflow contribute to a better understanding of the electrocatalytic system at the early stages of development and provide important insights for the evaluation of novel materials that are to be used in large-scale industrial applications.

Abstract The wetting of battery electrodes with electrolyte is a time- and cost-intensive process step. One of the biggest problems is the time it takes for the liquid electrolyte to be absorbed into the porous electrode. To reduce this wetting time, laser structured electrodes can be used. The resulting grooves facilitate deeper penetration of the electrolyte during the wetting process, leading to faster wetting. Multiphysics simulations and measurement data will be used to optimize the wetting process and to investigate the influence of the structuring geometry on the wetting time. In addition to modelling the structured electrode, achieving a suitable meshing is crucial. Moreover, the physical behavior of the wetting process will be represented by selecting appropriate and realistic boundary conditions. Capillary effects and fluid flow in porous media will be considered to describe the wetting process. The computer model will be validated using measurement data. In this paper it is shown that the wetting time can be significantly reduced by using structured electrodes. It is also shown that the wetting time is further reduced for smaller distances between the grooves. The software COMSOL MULTIPHYSICS will be used to create the model.

Lithium‐sulfur batteries have the potential to replace lithium‐ion batteries in the future due to their high theoretical capacity and energy density but suffer from low cycling stability caused by the polysulfide shuttle. This work demonstrates a reduction of the polysulfide shuttle and increased cycling stability by using iron oxide and chromium oxide as additives for a simply fabricated lithium sulfide cathode. Adsorption isotherms were recorded, and monolayer adsorption capacities were determined for a better understanding of the interactions between transition metal oxides and polysulfides. A significant reduction of the shuttle mechanism can be deduced from the cyclization experiments. Similarly, the catalytic influence of chromium oxide and iron oxide on the oxidation could be shown by cyclic voltammetry.

Cell temperature of hard carbons is varied under open circuit conditions (entropy profiling) during sodiation. Features vary with pore size, revealing the nanopore filling onset. Sodium binding energy scales inversely with pore curvature radius.

Akademische Forschung und industrielle Anwendung – wie die Zusammenarbeit zwischen Industrie und Akademia zu optimieren ist, zeigt ein Blick aus der technischen Elektrochemie auf deren Anwendung in der Industrie. Wichtig ist dabei eine klare Kommunikation auf beiden Seiten.

Abstract The oxygen evolution reaction (OER) as one half‐cell reaction of electrochemical water splitting has a fundamental impact on water splitting efficiency and thus on the competitiveness of electrochemically generated hydrogen in the energy market. Nickel‐iron layered double hydroxides (NiFe LDH) are among the most promising electrocatalysts for efficient OER under alkaline conditions. Despite intensive research, correlations of the material properties and the resulting kinetically limiting surface processes are poorly investigated. This work focuses on the kinetic behavior of NiFe LDH catalysts containing different anions in the basal spacing in alkaline OER. Steady‐state Tafel plots, impedance measurements as well as reaction order plots were used to elucidate differences in the catalytic performance. All catalysts showed a dual Tafel behavior and fractional reaction orders. For kinetic modelling, the physisorbed hydrogen peroxide mechanism and Temkin adsorption model were adopted to fit experimental data. Our study showed that the intercalated anions affect the kinetics of rate determining steps. The hypophosphite intercalated LDH possessed the highest OER activity and the first step as rate determining. While for both carbonate and borate intercalated NiFe LDH, the second step proved to be rate determining in the low Tafel region, while the first step was found to be rate‐limiting in the high Tafel region.

Sodium-ion batteries (NIBs) utilize cheaper materials than lithium-ion batteries (LIBs) and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterize LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimize cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge.

We present a study of battery ageing, comparing pristine, calendar-aged, and cycle-aged lithium-ion cells. Insight into degradation was obtained via differential voltage analysis and by estimating and tracking changes in a subset of electrochemical model parameters of the single particle model through inverse modelling. We show that both diffusion time and kinetic overpotential increase in cycle-aged cells, while calendar-aged cells experienced no diffusion time changes but some kinetic overpotential increase. The latter is also evident in 50% higher irreversible heat generation in cycle-aged cells. This study highlights the importance of updating battery model parameters during ageing.

Graphite-silicon (Gr-Si) blends have become common in commercial Li-ion battery negative electrodes, offering increased capacity over pure graphite. Lithiation/delithiation of the silicon particles results in volume changes, which may be associated with increased hysteresis of the open circuit potential (OCP). The OCP is a function of both concentration and temperature. Entropy change measurement-which probes the response of the OCP to temperature-offers a unique battery diagnostics tool. While entropy change measurements have previously been applied to study degradation, the implications of Si additives on the entropy profiles of commercial cells have not been explored. Here, we use entropy profiling to track ageing markers in the same way as differential voltage analysis. In addition to lithiation/delithiation hysteresis in the OCP of Gr-Si blends, cells with Gr-Si anodes also exhibit differences in entropy profile depending on cycling direction, reflecting degradation-related morphological changes. For cycled cells, entropy change decreased during discharge, likely corresponding to graphite particles breaking and cracking. However, entropy change during charge increased with cycling, likely due to the volume change of silicon. Over a broad voltage range, these combined effects led to the observed rise in entropy hysteresis with age. Conversely, for calendar aged cells entropy hysteresis remained stable.

Recently, zinc-air batteries have received revived interest as one of the proposed post lithium-ion technologies. This revival is driven by the demand for safe and environmentally friendly energy storage solutions for fluctuating renewable energy. These energy storage systems need to address variable power, capacity and profitability requests. Zinc-air-flow batteries with high specific energy density, low-cost, highly available and eco-friendly active materials are suitable to fulfill these requirements. The use of a flow battery type with zinc-particles suspended in an alkaline solution (zinc-slurry) in addition to high performance oxygen-reduction electrodes enables the development of high-power zinc-air batteries. Usually, the energy density of zinc-air-flow cells is limited by the solubility of the oxidation products in the electrolyte. In our cell, the electrolyte is supersaturated with oxidation products, before finally ZnO precipitates from the electrolyte. The cell is therefore operated beyond zincate solubility limit, which allows higher specific capacities than reported in literature, even though the zincate solubility of the electrolyte is much lower than reported [1]. The flow cell has an active area of 100 cm² and incorporates a copper plate as current collector for the zinc-suspension electrode and an oxygen reduction electrode with gas-diffusion layer (supplied by Covestro). The zinc-slurry contains zinc-particles (supplied by Grillo) suspended in an alkaline solution (30 wt.-% KOH) and stabilized with polyacrylic acid. One of the main limiting factors of the specific capacity of the zinc-slurry is passivation. While the passivation of stationary electrodes in flowing or quiescent electrolytes is fairly well understood, see e. g. [2], there is no literature on the passivation behaviour of zinc-slurry electrodes. In this study we determined the starting point of ZnO precipitation and the critical factor for the passivation of these anodes by analysing cell voltage, potential of the zinc electrode and the zincate concentration in the liquid phase of the zinc-slurry. Depending on parameters like current density and additive selection, it is possible to reach specific capacities of 287 mAh/gslurry or 574 mAh/gzinc. Appleby, A.J. and M. Jacquier, The C.G.E. circulating zinc/air battery: A practical vehicle power source. Journal of Power Sources, 1976. 1(1): p. 17-34. Bockelmann, M., et al., Electrochemical characterization and mathematical modeling of zinc passivation in alkaline solutions: A review. Electrochimica Acta, 2017. 237: p. 276-298.

Computational modelling is a vital tool in the research of batteries and their component materials. Atomistic models are key to building truly physics-based models of batteries and form the foundation of the multiscale modelling chain, leading to more robust and predictive models. These models can be applied to fundamental research questions with high predictive accuracy. For example, they can be used to predict new behaviour not currently accessible by experiment, for reasons of cost, safety, or throughput. Atomistic models are useful for quantifying and evaluating trends in experimental data, explaining structure-property relationships, and informing materials design strategies and libraries. In this review, we showcase the most prominent atomistic modelling methods and their application to electrode materials, liquid and solid electrolyte materials, and their interfaces, highlighting the diverse range of battery properties that can be investigated. Furthermore, we link atomistic modelling to experimental data and higher scale models such as continuum and control models. We also provide a critical discussion on the outlook of these materials and the main challenges for future battery research.

The literature surrounding entropy changes accompanying degradation is scarce and limited to solely graphite anode cells. Meanwhile, graphite-silicon blends become frequent in commercial applications due to their considerable capacity advantage. The lithiation/delithiation results in volume changes of the silicon particle, which has been reported to cause an increased hysteresis [1] of the open circuit potential (OCP). Our hypothesis is that entropy reflects certain morphological changes occurring within the electrode and consequently, entropy hysteresis is also higher for electrodes containing silicon. We further postulate that entropy hysteresis increases with cycle age. If the hypothesis is correct, entropy measurement will offer a unique insight into battery degradation among commonly used differential voltage analysis (DVA) and incremental capacity analysis (ICA). To test our hypothesis, we adapted an accelerated entropy measurement method proposed by Osswald et al. [2] on high-energy NCA/Gr-Si cylindrical cells, with ~10 wt % Si and ~90 wt % Gr anode composition. The cells were divided into two groups; the first group was stored at an elevated temperature to act as an example of accelerated calendar ageing, while the second group experienced cycle ageing. Subsequently, we performed DVA and ICA to provide a direct comparison with the entropy results and checked for correlation. In accordance with the hypothesis, the entropy behaved similarly to the OCP. Entropy hysteresis remained stable for calendar aged cells (Fig. 1 a) but increased considerably for cycled cells (Fig. 1 b). Silicon volume expansion and its 'breathing' effect [3,4] caused charge entropy to increase with cycle age. Graphite particles experienced breaking and cracking, which prompted a decrease in discharge entropy during cycling. These combined effects led to the observed rise in entropy hysteresis over time. A direct comparison of entropy profiling with DVA revealed alike characteristics. Based on abrupt energy level changes accompanying phase transitions, entropy profiling was successfully used to track ageing markers, aiding recognition of a loss of active material on positive (LAMPE) and negative (LAMNE) electrodes as well as loss of lithium inventory (LLI). Both DVA and entropy profiling revealed that LLI was the main degradation mode for the calendar aged cell, while LAMNE combined with LLI for the cycled cell. Plotting entropy against voltage allowed for additional observations. Horizontal shift towards higher voltages occurred due to the rise in internal resistance but also LLI. While some authors [5] successfully obtained information about LAMPE and LAMNE from ICA, and an analogy can be performed for entropy profiling, it is difficult to draw definitive conclusions from these results. The fact that entropy profiling reflects microscopic changes occurring within electrodes, and considers also ageing markers, makes it a unique, non-invasive tool among ICA and DVA. However, its application is not straightforward and needs further validation. A possible avenue to be explored is the theoretical simulation of pristine and aged entropy profiles to cross-validate with our experimental data. References: [1] Marco-Tulio F. Rodrigues, James A. Gilbert, Kaushik Kalaga, and Daniel P. Abraham. Insights on the cycling behavior of a highly prelithiated silicon–graphite electrode in lithium-ion cells. JPhys Energy, 2(2), 2020. [2] Patrick J. Osswald, Manuel Del Rosario, Jurgen Garche, Andreas Jossen, and Harry E. Hoster. Fast and Accurate Measurement of Entropy Profiles of Commercial Lithium-Ion Cells. Electrochimica Acta, 177:270–276, 2015. [3] McBrayer, Josefine D. and Rodrigues, Marco-Tulio F. and Schulze, Maxwell C. and Abraham, Daniel P. and Apblett, Christopher A. and Bloom, Ira and Carroll, Gerard Michael and Colclasure, Andrew M. and Fang, Chen and Harrison, Katharine L. and Liu, Gao and Minteer, Shelley D. and Neale, Nathan R. and Veith, Gabriel M. and Johnson, Christopher S. and Vaughey, John T. and Burrell, Anthony K. and Cunningham, Brian Calendar aging of silicon-containing batteries. Nature Energy, 6(9):866–872, 2021. [4] Gabriel M. Veith, Mathieu Doucet, J. Kevin Baldwin, Robert L. Sacci, Tyler M. Fears, Yongqiang Wang, and James F. Browning. Direct Determination of Solid-Electrolyte Interphase Thickness and Composition as a Function of State of Charge on a Silicon Anode. Journal of Physical Chemistry C, 119(35):20339–20349, 2015. [5] Alexander J. Smith, Pontus Svens, Maria Varini, Goran Lindbergh, and Rakel Wreland Lindstrom. Expanded In Situ Aging Indicators for Lithium-Ion Batteries with a Blended NMC-LMO Electrode Cycled at Sub-Ambient Temperature. Journal of The Electrochemical Society, 168(11):110530, 2021. Figure 1

Understanding and optimizing single particle rate behaviour is normally challenging in composite commercial lithium-ion electrode materials. In this regard, recent experimental research has addressed the electrochemical Li-ion intercalation in individual nanosized particles. Here, we present a thorough theoretical analysis of the Li+ intercalation voltammetric behaviour in single nano/micro-scale LiMn2O4 (LMO) particles, incorporating realistic interactions between inserted ions. A transparent 2-dimensional zone diagram representation of kinetic-diffusional behaviour is provided that allows rapid diagnosis of the reversibility and diffusion length of the system depending on the particle geometry. We provide an Excel file where the boundary lines of the zone diagram can be rapidly recalculated by setting input values of the rate constant, k0 and diffusion coefficient,D . The model framework elucidates the heterogeneous behaviour of nanosized particles with similar sizes but different shapes. Hence, we present here an outlook for realistic multiscale modelling of real materials.

The main challenge for acidic water electrolysis is the lack of active and stable oxygen evolution catalysts based on abundant materials, which are globally scalable. Iridium oxide is the only material which is active and stable. However, Ir is extremely rare. While both active materials and stable materials exist, those that are active are usually not stable and vice versa. In this work, we present a new design strategy for activating stable materials originally deemed unsuitable due to a semiconducting nature and wide band gap energy. These stable semiconductors cannot change oxidation state under the relevant reaction conditions. Based on DFT calculations, we find that adding an n-type dopant facilitates oxygen binding on semiconductor surfaces. The binding is, however, strong and prevents further binding or desorption of oxygen. By combining both n-type and p-type dopants, the reactivity can be tuned so that oxygen can be adsorbed and desorbed under reaction conditions. The tuning results from the electrostatic interactions between the dopants as well as between the dopants and the binding site. This concept is experimentally verified on TiO2 by co-substituting with different pairs of n- and p-type dopants. Our findings suggest that the co-substitution approach can be used to activate stable materials, with no intrinsic oxygen evolution activity, to design new catalysts for acid water electrolysis.