Composite cathode composed of active particles and solid electrolytes (SEs) can considerably enlarge the particle-SE contact areas and achieve high areal loadings in all-solid-state batteries (ASSBs). However, the challenging interfacial instability and particle damage problems remain unsolved. Herein, we establish a 3D electrochemical-mechanical coupled model to investigate the underlying failure mechanism by considering the governing electrochemical and physics processes. Micro-scale heterogeneous primary particles with random crystallographic orientation and size inside the LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111) secondary particle of the model result in the anisotropic Li diffusion and volume variation within the secondary particle, leading to significant nonuniformity of the Li concentration, and GPa-level stress distributions at primary particle boundaries, and finally causing the particle internal cracks. The particle volume shrinkage under the constraint of stiff Li₇La₃Zr₂O₁₂ (LLZO) SE triggers the interface debonding (gap>50 nm) with increased interfacial impedance to degrade cell capacity. Higher C-rates result in larger residual stress (∼100 MPa)/strain/debonding gap at discharging end, more likely to deteriorate the cell performance. Increasing the interfacial strength between the particle and SE can suppress the interface debonding but induces high stress (up to 10 GPa). Results reveal the underlying mechanism of the electrochemical-mechanical coupling failure mechanism for composite cathode and provide promising guidance on the further improvement of a more robust composite cathode for ASSBs.

由活性颗粒和固体电解质 (SEs) 组成的复合正极可以显着扩大颗粒与 SE 的接触面积，并在全固态电池 (ASSBs) 中实现高面积负载。然而，具有挑战性的界面不稳定和粒子损伤问题仍未解决。在此，我们建立了一个 3D 电化学-机械耦合模型，通过考虑控制电化学和物理过程来研究潜在的失效机制。_{LiNi 1/3} Co _1/3 Mn _1/3 O ₂内部具有随机晶体取向和尺寸的微尺度异质初级粒子(NCM111)模型的二次粒子导致二次粒子内部Li的各向异性扩散和体积变化，导致Li浓度显着不均匀，一次粒子边界出现GPa级应力分布，最终导致粒子内部开裂。_{刚性Li 7} La ₃ Zr ₂ O ₁₂约束下的颗粒体积收缩(LLZO) SE 触发界面剥离（间隙 > 50 nm），界面阻抗增加，从而降低电池容量。较高的倍率导致放电端的残余应力（~100 MPa）/应变/脱粘间隙较大，更有可能降低电池性能。增加颗粒和 SE 之间的界面强度可以抑制界面脱粘，但会产生高应力（高达 10 GPa）。结果揭示了复合阴极电化学-机械耦合失效机制的潜在机制，并为进一步改进用于 ASSB 的更坚固的复合阴极提供了有希望的指导。