Panoramic modeling of lithium dendrite formation and crack penetration in solid-state electrolyte: Mechanism and suppression strategies

New multi-phase field model is proposed to study Li penetration in solid-state electrolyte (SE). Different from previous work, in which dendrite growth and crack propagation are directly linked by assuming Li instantaneously filled crack region, in present model, dendrite growth is not synchronized with crack propagation. Thus, the panoramic process of Li penetration in SE has been characterized, involving initial dendrites formation; crack nucleation and propagation; filling of Li in crack that accelerates crack extension causing fragmentation of SE and leaving many crack regions unfilled. Simulation results shows that stress plays a competition role in Li penetration: on one hand, it suppresses reaction; on the other, it induces crack., The latter, in general, is more significant. Thus, stiffening of SE not suppresses but promotes dendrite penetration. The increase of fracture toughness of SE can completely inhibit crack. In this case, a window to suppress lithium penetration by stiffening of SE is obtained. Applied in-plane compression also inhibit cracking. However, once cracking is completely inhibited, further increasing compression is no longer benefit for dendrite suppression or even promotes it due to mechano-electrochemical coupling.