Abstract
All-solid-state lithium batteries (ASSLBs) offer enhanced safety, high energy density, and broad operating temperature ranges. However, dendrite nucleation and propagation through the solid-state electrolyte remains a critical barrier to commercialisation. The coupled influence of the interfacial electrochemical reaction rate, applied voltage, and stacking pressure on dendrite propagation behaviour is not yet fully understood. This study presents a computational phase-field analysis of the Li dendrite growth at the Li/LLZO interface, assuming preferential propagation along the GB pathways of the polycrystalline LLZO solid electrolyte. A systematic parametric study comprising 125 cases was conducted across combinations of applied voltage, stacking pressure, and interfacial reaction rate. The results reveal four distinct dendrite propagation stages governed jointly by applied voltage and stacking pressure: a single-channel regime at low voltage, two pressure responsive branching regimes at intermediate voltage, and a fully percolated, voltage dominated regime at high voltage. Stacking pressure effectively suppresses dendrite growth within a reaction-rate-dependent voltage window, however, this window shifts to lower voltages and narrows as the interfacial reaction rate increases. Reducing the interfacial reaction rate is demonstrated to be a substantially more effective suppression strategy than increasing external stacking pressure, highlighting interfacial engineering as the priority design lever for next-generation ASSLB development.