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

Abstract 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 Li_{1 + x + y}Al_x(Ge,Ti)_{2 - x}Si_yP_{3 - y}O₁₂, 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.