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There are various component contacts in porous electrodes, such as the direct contact between the active particles and the particle–current collector, during electrode manufacturing and lithium‐ion battery electrochemical cycles. Herein, an electrochemical–mechanical representative volume element model is developed to study the contact behavior of porous electrodes. For the direct contact behavior of multiple particles, stronger battery constraints and larger size differences enhance the reduction in Li‐ion concentration in the contact area of the active particles in the porous electrode and the contact stress in the porous electrode particles. For the contact between the active particles and current collector, the decrease in the elastic modulus of the current collector slightly increases the contact radius and significantly reduces the contact stress. By comparing the contact area and contact stress of the smooth and rough current collectors, the latter has a smaller contact area and larger contact stress when in contact with active particles. These findings provide insights into designing Li‐ion batteries from the perspective of contact stress to minimize the mechanical failure of porous electrodes. [ABSTRACT FROM AUTHOR]

The optimization of traction-separation parameters within the cohesive zone model (CZM) is crucial for accurately simulating electrode peeling failure in lithium-ion batteries. This study performed 180° peeling tests on NCM electrodes and used Abaqus software alongside the sim-flow optimization tool for simulation analysis, aiming to accurately replicate the failure behavior at the lithium-ion battery electrode interface. Experimental results were used to determine the fracture energy of the electrode interface, while numerical simulations analyzed the peeling performance of the electrode. By fitting the force-displacement curves from both simulation and experiment, the traction-separation parameters within the bilinear CZM were optimized. Additionally, the study analyzed the effects of traction-separation parameters, as well as the modulus and thickness of the current collector, on peeling behavior. The results showed that a significant increase in the interface stiffness and strength increased the steady-state peeling force. Among these, the fracture energy had the most significant influence on the steady-state peeling force. Furthermore, while the modulus and thickness of the current collector affected the maximum peeling force, their effect on the steady-state peeling force was negligible. These findings enhance the accuracy of simulating the failure behavior of the electrode interface. [Display omitted] [ABSTRACT FROM AUTHOR]

The effects of hydrostatic pressure and modulus softening on electrode curvature and stress in a bilayer electrode plate are studied. It is found the hydrostatic pressure facilitates Li-ion diffusion. Modulus softening can weaken the stress assisted diffusion, promote the electrode to bend and reduce the stress. The electrode would nearly reach a lock-up state of deformation in the late charging process for potentiostatic charging, but the electrode bends continuously for galvanostatic charging. It is also found the electrode curvature firstly increases, and then reduces as current collector thickness increases, but decreases continuously by increasing the modulus of current collector. The thicker current collector and higher rigidity of current collector can block Li-ion diffusion for potentiostatic charging. Finally, the optimized charging procedure for reducing the bending deformation is galvanostatic first followed by potentiostatic, the current collector should be as thin and soft as possible when its own strength and role are satisfied. [ABSTRACT FROM AUTHOR]

Thick electrodes whose active materials have high areal density may improve the energy densities of lithium-ion batteries. However, the weakened rate abilities and cycle lifetimes of such electrodes significantly limit their practical applications. In this study, a modified two-dimensional model was built to evaluate the influence of the electrode structure on the lithiation process. Gradient electrodes with different particle sizes along the thickness direction are designed and fabricated via a two-layer coating process. The gradient design in the thickness direction is confirmed by three-dimensional digital microscopy, energy-dispersive spectroscopy, X-ray diffraction, and scanning electron microscopy. Galvanostatic charge/discharge cycling tests and electrochemical impedance spectroscopy are performed to investigate the electrochemical properties of the fabricated gradient electrodes. The simulation results indicate that the gradient electrode structure can enhance the utilization of electrode particles on the current collector side and alleviate the nonuniformity of the solid-phase Li concentration along the thickness direction. High electrochemical performance and long-term cycling stability of the designed gradient electrodes are verified by electrochemical test. The gradient structure fabricated via multi-layer coating processes can be used to improve the electrochemical performance of thick electrodes. [ABSTRACT FROM AUTHOR]