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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]

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]