Microstructure and Pressure Driven Electrodeposition Stability in Solid-State Batteries

Abstract

Interfacial deposition stability at the lithium metal-solid electrolyte interface in all solid-state batteries (ASSB) is governed by the stress-transport-electrochemistry coupling in conjunction with the polycrystalline/amorphous solid electrolyte architecture. In this work, we delineate the optimal solid electrolyte microstructure comprising of grains, grain boundary and voids possessing desirable ionic conductivity and elastic modulus for superior transport and strength. An analytical formalism is provided to discern the impact of external “stack” pressure induced mechanical stress on electrodeposition stability; stress magnitude obtained are in the megapascal range considerably diminishing the stress-kinetics effects. For experimental stack pressures ranging up to 10 MPa, the impact of stress on reaction kinetics is negligibly small and electrolyte transport overpotentials dictate electrodeposition stability. We detail the deposition stability phase map as a function of solid electrolyte to Li metal shear modulus and molar volume ratios under varying operating conditions including external pressure, surface roughness, applied current density and ambient temperature. High current density operation with stable deposition can be ensured with ample external pressure, high temperature and low surface roughness operation for low shear modulus ratio of the solid electrolyte to Li metal. <br>

Unraveling the Li Penetration Mechanism in Polycrystalline Solid Electrolytes

“…Moreover, the theoretical studies show the interfacial stress is on the order of a few megapascals. [ 26,34–36 ] Thus, through the calibration, the constants related to the inelastic strain are determined to be K ii = 2.1 × 10 −4 . All simulation parameters are listed in Table S1 (Supporting Information) and more details can be found in Supporting Information.…”

Unlocking the Electrochemical–Mechanical Coupling Behaviors of Dendrite Growth and Crack Propagation in All‐Solid‐State Batteries

“…[ 8a,22 ] By direct numerical simulation of restructured SE microstructure, the effective SE properties were obtained, and the effects of operating conditions, including temperature and external pressure, were parametrically studied. [ 23 ] The stack pressure and SE electrochemical properties were found able to influence the interfacial deposition and mechanical stability. [ 13a ] The interaction mechanism of crack propagation and dendrite growth under stacking pressures and the interfacial defect was further explored by the one‐way coupled electrochemical‐mechanical phase‐field model.…”