Characteristics of discharge products in all-solid-state Li-air batteries

•All solid-state lithium–air batteries•Platinum pattern electrode on a LATP•The reaction product is Li2O2.•The ORR proceeds on the surface of the Li2O2 reaction product.

The reaction product and reaction site for solid-state lithium–air batteries were examined using a platinum pattern electrode on a lithium conducting solid electrolyte. The cell consisted of a lithium metal anode, a protective layer consisting of polyethylene oxide with the Li(CF3SO2)2N lithium salt, a lithium conducting solid electrolyte of Li1 + x + yAlx(Ge,Ti)2 − xSiyP3 − yO12, and a sputtered platinum striped pattern air electrode. The cell was discharged at 1.0 μA cm− 2 for 300 h and the reaction product was analyzed using Raman spectroscopy and X-ray photoelectron spectroscopy. The reaction product of Li2O2 was observed at the triple phase boundaries of oxygen, platinum and electrolyte, in addition to on the platinum and solid electrolyte surfaces. This result suggests that the oxygen reduction reaction can proceed on the surface of the Li2O2 reaction product.