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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]

Lithium metal is an ideal anode material for high‐energy‐density rechargeable batteries. However, harmful dendrites lead to short circuit and cause safety hazards. Herein, a fundamental study on increasing the roughness of the electrode and its influence on the behaviors of lithium dendrites by combining experiment and simulation is presented. Various aspects of the growth behaviors of lithium dendrite on the electrode surface are investigated with consideration of the overpotential, roughness, and the solid electrolyte interphase (SEI). In situ observation of experimental results show that the electrode surface becomes rough gradually during the charging process, and the rough electrode surface promotes the formation of disordered dendrites. The simulation results also show that it is easy to form dendrites on the surface of electrodes with higher roughness. Higher overpotential leads to uneven deposition of reduced lithium and promotes the formation of lithium dendrites. A thicker SEI and lower conductivity can effectively slow down the growth of dendrites. Herein, the overpotential, protuberance, and SEI are preliminarily designed to suppress the growth of dendrites effectively. These results supply useful information for the optimal design of electrode surface patterns and an artificial SEI. [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]

• An analytical model was established to characterize the mode-II energy release rate. • A novel plasticity-assisted zero-degree peeling test was proposed to obtain a stable crack propagation stage. • The effect of dimensionless stress, indices of hardening, and load transfer length on energy release rate were analyzed. • An excellent agreement between the theoretical calculation and numerical result was demonstrated. Lithium-ion batteries integrate heterogeneous materials such as active layers and current collectors, resulting in interfaces prone to delamination during the charge/discharge process. The mode-II energy release rate is a key index to evaluate the interfacial adhesion properties and structural integrity of electrodes. In this study, an analytical model considering the energy balance principle and a nonlinear constitutive model was established to characterize the mode-II energy release rate. A novel plasticity-assisted zero-degree peeling test (PAZDPT) is proposed to obtain a stable crack propagation stage where the peeling force is determined to calculate the mode-II energy release rate. Several parameter studies were conducted to verify the approximation of the stress distributions and simplification of the analytical model. The accuracy of the analytical model was validated against finite-element calculations. The results demonstrated an excellent agreement between the theoretical calculation and numerical results. Moreover, PAZDPT is conducive to steady crack propagation because it restricts the energy accumulation around the crack tip. The analytical model and newly proposed PAZDPT can also be extended to determine the mode-II energy release rate of other types of interfaces in bilayer thin-film materials. [ABSTRACT FROM AUTHOR]