Microstructure and Pressure-Driven Electrodeposition Stability in Solid-State Batteries

Interfacial deposition stability at the Li-metal-solid electrolyte inter center dot face in all solid-state batteries 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 grains, grain boundaries, 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; the stress magnitudes 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. High current density operation with stable deposition can be ensured with ample external pressure, high temperature, and low surface roughness operation for a low shear modulus ratio of the solid electrolyte to Li-metal.

Automated summary

The stability of interfacial deposition at the Li-metal-solid electrolyte interface in all solid-state batteries is influenced by the stress-transport-electrochemistry coupling and the polycrystalline/amorphous solid electrolyte architecture. The study identifies the optimal solid electrolyte microstructure with desirable ionic conductivity and elastic modulus for superior transport and strength. Experimental results show that external stack pressure has a negligible impact on reaction kinetics, with electrolyte transport overpotentials playing a key role in electrodeposition stability.