The Effect of High Binder Content in Argyrodite-Type Separators for Solid-State Pouch Cells Tested under Different Temperature and Pressure Conditions

Solid-state batteries are gaining momentum in several industries, such as automotive and mobile technologies. With prospects for high energy density and safety, these batteries could replace conventional lithium-ion batteries. In this work, the effect of a high binder content in an argyrodite-type electrolyte was investigated. The ionic conductivity was calculated by impedance measurements, which resulted in a conductivity of 0.72 mS/cm for a 10 wt.% polyisobutylene binder content. The electrolyte was then tested in a Pouch cell with a Ni-rich composite cathode and a Li-In alloy at the anode side under different temperature and pressure conditions. The formation of a polymer layer on the separator was seen, which created a high-resistance interface with the anode. This interface was identified by impedance measurements during cycling, which reported very high internal resistances in the full cell. This reduced the capacity of the cells considerably, especially at high currents where the kinetic factor is more crucial.