LPS and LLZO inorganic solid electrolytes have been the workhorse of solid battery efforts for the past 20 years. LPS (or sulfur based) solid electrolytes have a lithium ion conductivity higher than liquid electrolytes and are softer and easier to process into separators than LLZO. However, their electrochemical stability is quite narrow on the anode as well as on the cathode side which require protective coatings for compatibility. One common method to interface high conductivity LPS with metallic lithium anode is to use a PEO polymer interface between the reactive lithium anode and the LPS solid electrolyte separator. In this podcast i discuss the stability of LPS with the PEO membrane.