A Bifunctional Chemomechanics Strategy To Suppress Electrochemo-Mechanical Failure of Ni-Rich Cathodes for...

Electrochemo-mechanical failure of Ni-rich cathodes leads to rapid performance degradation, and thus hinders their practical implementation in all-solid-state lithium batteries (ASSLBs). To solve this problem, herein, we propose a bifunctional chemomechanics strategy by protecting polycrystalline LiNi_0.6Co_0.2Mn_0.2O₂ (NCM) cathodes using a high-mechanical-strength fast ionic conductor LiZr₂(PO₄)₃ (LZP) coating layer. The coating layer's synergistic effect between mechanical strength and electrochemical stability is studied in Li₆PS₅Cl (LPSCl)-based ASSLBs for the first time. Using finite element method (FEM) simulations and various characterization techniques, we demonstrate that the robust and stable LZP (Young's modulus 140.7 GPa, electrochemical stability window >5 V) coating layer mitigates the volume change and particle disintegration of polycrystalline NCM and electrochemical decomposition of LPSCl on the LPSCl/NCM interface. As a result, the LZP-modified ASSLBs display remarkably improved reversible capacity, cycle life, and rate performance. The synergy of mechanical and electrochemical properties of the coating layer will provide valuable guidance for the development of high-energy-density ASSLBs.