The mechanical properties of gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs critically govern compression-dependent transport phenomena that control local performance and durability. This work presents a systematic, self-consistent characterization of orthotropic mechanical behavior, through-plane (TP) thermal and electrical conductivities, in-plane (IP) gas permeability, and structural properties for five commercial GDLs—wet-laid carbon papers (Toray TGP-H-060 with 5 and 30 wt% PTFE; SGL 29BA uncoated; SGL 28BC MPL-coated) and one hydroentangled non-woven (Freudenberg H23C7)—measured under controlled compressive loads (0.5–3 MPa). Additional GDL materials are benchmarked against literature data. Increased PTFE content significantly stiffens the fibrous network, while microporous layer (MPL) addition introduces additional through-plane bulk transport resistance. In-plane gas permeability decreases by approximately 70–90% over the investigated compression range for all materials, with the most pronounced reductions (up to two orders of magnitude) observed in SGL 28BC due to pronounced MPL intrusion into the substrate, forming a mixed fiber–MPL zone that reduces lateral macropore connectivity and increases flow resistance. Physically motivated models are applied to interpret the observed trends. Effective percolation theory correlations describe the nonlinear evolution of thermal and electrical conductivities with solid volume fraction, yielding interpretable parameters that explain material class differences and thermal − electrical decoupling. In addition, a hyperelastic two − power-law strain energy framework that mechanistically captures the full compressive response − from initial fiber bending, through topology-controlled stiffening, to high-strain densification − while maintaining thermodynamic consistency and finite-element compatibility is proposed. While Toray TGP-H-060 is extensively benchmarked in the literature, coupled compression-dependent multi-property datasets remain scarce for hydroentangled non-woven GDLs and MPL-coated roll-good grades. The comprehensive dataset and modeling framework presented here provide a robust foundation for high-fidelity three-dimensional PEMFC stack simulations, enabling improved material selection, stack design, and performance and durability optimization.

Water is a key factor in anion-exchange membrane fuel cells, since it is both a product and a reactant, and humidifies the membrane and the ionomer phase. To optimize the operation conditions preventing cathode drying and anode flooding, better knowledge on the water transport is needed. In this work, the water transport across an AemionTM membrane is quantified for different applied water partial pressure differences and current densities. Two membrane thicknesses, 25 and 50 μm, are studied, as well as two gas diffusion layers (GDLs) of different hydrophobicity: the hydrophobic Sigracet 25BC treated with polytetrafluoroethylene (PTFE), and Freudenberg H23C2 being hydrophilic as it is not treated with PTFE. The measurements show that having a hydrophilic GDL on both electrodes results in poor electrochemical performance, and restricted water transport. Although the highest water molar flux was observed for hydrophilic GDL on cathode and hydrophobic GDL on anode, the best electrochemical performance was observed for the opposite combination. A water transport model considering absorption/desorption resistance, electroosmotic drag and diffusion was deployed. The best fit of the model to the experimental data was obtained with a water drag coefficient of 2, and almost about 30% difference in absorption/desorption coefficient due to different GDLs.

This paper presents a modelling framework for incorporating wall interactions into the Maxwell-Stefan equations for ideal gases in porous media. In contrast to already existing models in literature, such as the Dusty Gas, Binary Friction and Modified Binary Friction models, the framework makes use of N−1 (with N being the number of gas species) independent mass balances for the gas species in combination with a total fluid momentum balance. This approach has the advantage that already existing numerical schemes for fluid momentum balances, such as Darcy's law or the Brinkman equations, can be used with only minor modifications. It also allows for separate initialisation of the velocity and pressure fields, something that is often beneficial when solving convection–diffusion equations numerically. The derived model is validated against both stationary and time-dependent experimental data from literature for binary Ar-He systems in porous media, using Knudsen diffusivities to define the wall friction terms.

Highlights Fully coupled (electro-chemo mechanics) phase field approach to characterize the fracture behavior. Highly heterogeneous electrochemical and mechanical response of randomly oriented polycrystalline NMC active particle is predicted. Mechanical degradation of polycrystalline NMC particle caused by significant particle cracking in the first charge cycle. Quantifying the electrochemically active surface area due to intergranular and intragranular particle fracture. Electrochemical performance analysis of polycrystalline NMC particle during the first charge cycle considering particle cracking plus electrolyte penetration.

Conditions such as the temperature and pressure experienced by lithium-ion battery components are dependent oncell geometry and can vary widely within a large cell. The resulting uneven degradation is challenging to study at thefull cell level but can be revealed upon disassembly and post mortem analysis. In this work, we report localizedlithium plating in automotive-grade, prismatic lithium-ion cells, also under cycling conditions generally consideredto be mild (e.g., 5–65 %SOC, 23 ◦C, 0.5C cycle rate). Dead lithium content is quantified using 7Li nuclear magneticresonance spectroscopy in both electrode and separator samples, corresponding to substantial capacity fade(26–46%) of the full cells. Severe lithium plating is typically initiated in regions near the positive tab, in which boththe separators and negative electrodes are ultimately deactivated. High pressure arises during cycling, and wepropose a deactivation mechanism based on high local stress due to electrode expansion and external constraint.Further, we develop a model to demonstrate that component deactivation can result in lithium plating even undermild cycling conditions. Notably, components harvested from regions with no detected lithium plating maintainedadequate electrochemical performance.

As a part of battery system operation, battery models are often used to determine battery characteristics such as the state of charge (SOC) and the state of health (SOH). A phenomenon that has a large impact on battery model accuracy for NiMH batteries is open circuit voltage (OCV) hysteresis, which causes the OCV to differ not only with the SOC of the battery but also with the charge-discharge history. This characteristic is especially influential when running the system in applications with dynamic current patterns. A model including a way to emulate battery hysteresis behavior would improve the battery management system function. In this study a lumped battery model for cell voltage prediction was expanded to include an OCV hysteresis model. Different expressions to describe the hysteresis behavior were explored. The different models were then evaluated using both synthetic and real-life application experimental data. In all cases the error was reduced by adding a hysteresis component to the model. Using this type of model in the battery management system of stationary energy storage systems based on NiMH batteries could help make the state prediction more accurate. This, in turn, would allow for better optimization of the system operation, something that could help increase system efficiency and lifetime.

Physics-based battery models are important tools in battery research, development, and control. To obtain useful information from the models, accurate parametrization is essential. A complex model structure and many unknown and hard-to-measure parameters make parametrization challenging. Furthermore, numerous applications require non-invasive parametrization relying on parameter estimation from measurements of current and voltage. Parametrization of physics-based battery models from input-output data is a growing research area with many recent publications. This paper aims to bridge the gap between researchers from different fields that work with battery model parametrization, since successful parametrization requires both knowledge of the underlying physical system as well as understanding of theory and concepts behind parameter estimation. The review encompasses sensitivity analyses, methods for parameter optimization, structural and practical identifiability analyses, design of experiments and methods for validation as well as the use of machine learning in parametrization. We highlight that not all model parameters can accurately be identified nor are all relevant for model performance. Nonetheless, no consensus on parameter importance could be shown. Local methods are commonly chosen because of their computational advantages. However, we find that the implications of local methods for analysis of non-linear models are often not sufficiently considered in reviewed literature.

Performance and aging of lithium-ion 18650 cylindrical cells containing NCA and Si-graphite composite electrodes are investigated during long-term low current rate (similar to 0.1C) cycling protocol resembling charge/discharge profile of off-grid photovoltaic battery system. The cells are cycled within 30% and 75% state-of-charge ranges ( increment SOC) with low, middle and high cut-off voltages. Electrochemical impedance spectroscopy data of full cylindrical cells exhibit severe aging for cells that have been cycled at higher cut-off voltage of 4.2 V. Symmetric cell impedance from each electrode shows that aging of NCA is dominant over aging of Si-graphite. Using a Newman-based impedance model, the NCA symmetrical cells' impedance spectra are parameterized to evaluate the aging modes. The resulting parameterization confirms increased particles' surface film resistance due to possible electrolyte oxidation and tortuosity increase at high cut-off voltages. Cycling the cells with middle and low cut-off voltages causes few significant changes when compared to calendar-aged samples. This opens up the possibility to significantly increase battery lifetime for small photovoltaic battery systems in rural areas of Bolivia.

To promote the development of anion exchange membrane fuel cells (AEMFC), an understanding of the oxygen reduction reaction (ORR) kinetics in porous gas diffusion electrodes is essential. In this work, experimental polarisation curves for electrodes with different platinum catalyst loadings and oxygen partial pressures at the cathode are fitted to a physics-based porous electrode model in the voltage range from open circuit voltage (OCV) to 0.7 V. Polarisation curves measured with different anode catalyst loadings, and hydrogen partial pressures, were used to verify the model. The reactions are described using a two-step Tafel-Volmer pathway at the anode and concentration-dependent Butler-Volmer kinetics at the cathode. A good fit to experimental data in the kinetic region is obtained with an exchange current density of 1.0.10(-8)Acm(-2), a first order dependency on oxygen partial pressure, and a charge transfer coefficient of 0.8 for the ORR. For lower oxygen partial pressure, hydrogen crossover is needed to explain the downward shift of the polarisation curves in the kinetic region. In the experimental data, the polarisation curves show an apparent limiting current density at lower hydrogen partial pressures, explained by the lower rate of the Tafel step at these conditions.