Nonintuitive Role of Solid Electrolyte Porosity on Failure

Solid electrolyte failure can occur through a range of different mechanisms. Electrochemical delamination at electrode and electrolyte interfaces is a prominent failure mechanism during high capacity and low N/P operating conditions, and filament formation is prevalent during a high rate and long cycle-life deposition. Interface coherency and the solid electrolyte microstructure both impact the ultimate degradation mode. The solid electrolyte microstructure, described in part by the density, periodicity, and interconnected arrangement of pores, plays a role in failure. Herein, we combine modeling, synchrotron imaging, and electrochemical experiments to systematically understand how densification and processing of solid electrolytes influence filament formation. The work reveals that the density of pores is not correlated with failure. Instead, the periodicity, size, and arrangement of pores is a driver for failure in amorphous solid electrolytes absent of grain boundaries.