The stability in batteries is dictated by the interfaces of the electrolyte and the electrodes. Regarding the lithium metal anode, the solid electrolyte interphase (SEI) is the key. With the help of organic species (PEO and LiTFSI), the stability of halide-based solid electrolytes towards lithium metal can be significantly improved. This is because of a stable SEI which prevents further reactions between solid electrolyte and lithium metal.

Halide-based solid electrolytes exhibit a large electrochemical stability window (ESW), making them compatible with high voltage cathode materials. This enables high capacities.