Mechanical failure in trench-architectured all-solid-state batteries with composite polymer electrolytes: structural...

Polymer-based trench-architectured all-solid-state batteries (ASSLIBs) offer exceptional safety and geometric adaptability for medical devices but suffer from stress-driven mechanical degradation at critical interfaces. Within these systems, composite solid polymer electrolytes (CSPE) face severe mechanical integrity challenges due to stress accumulation at trench tips and electrode interfaces. To address this, we integrate synergistic experimentation and coupled electrochemical-mechanical modeling to unravel mechanical failure and guide structural optimization. This study systematically investigates the mechanical properties of CSPE, the electrode and CSPE interfacial bonding performance and electrochemical performance. Based on these systematic experimental data, a coupled electrochemical-mechanical model integrating diffusion induced stress, viscoelastic constitutive laws, and cohesive zone theory was developed to simulate stress evolution and interface failure in trench-architectured ASSLIBs during operation. The simulations identify stress concentration at trench tips and interfacial debonding as dominant degradation mechanisms. Hence, balancing inorganic filler content, increasing trench arc radius and reducing discharge rates are proposed as optimization strategies to mitigate mechanical failure risks. This work establishes a data-driven framework for designing mechanically robust non-layered heteromorphic structural ASSLIBs by synchronizing electrolyte bulk strength, interfacial adhesion and geometric configurations.