Development and Optimization of Composite Cathode Materials for Use with Thin-Film Glassy Solid Electrolytes in Solid-State Batteries

Abstract

The electrochemical properties and thermal behavior of thin-film glassy solid electrolytes (GSE) in the [Li2S - SiS2 - LiPO3] system make them viable candidates for inclusion in solid-state batteries. To properly assess these electrolytes in the full-cell format, compatible composite cathode materials must be developed. These materials must be electronically and ionically conductive, and form a stable interface in contact with the GSE. A composite blend of redox-active lithium iron phosphate (LiFePO4), a mixed-oxy-sulfide glassy electrolyte, carbon nanotubes, a lithium solvate ionic liquid (SIL), and styrene butadiene rubber binder (SBR) was utilized to create the cathode material. Mixing time and order of component mixing were controlled in order to optimize for ionic and electronic conductivities within the bulk composite powder. With the addition of the SIL and SBR, a composite cathode blend capable of stably cycling in contact with the GSE was created.