Lithiation/delithiation of a Silicon Thin Film Electrode for All-Solid-State Batteries Using Operando X-ray Photoelectron Spectroscopy Apparatus

Abstract

Electrochemical lithiation/delithiation processes of a Si thin film sputter-deposited on a solid electrolyte sheet was investigated by x-ray photoelectron spectroscopy coupled with electrochemical analysis. After the first lithiation, a broad Li 1s peak composed of lithium silicides, lithium silicates, lithium oxide, and lithium carbonate appears. In addition, Si 2p peaks corresponding to bulk Si and native oxide significantly shift to lower binding energy due to the formation of lithium silicides and lithium silicates. After the successive delithiation, the Si 2p peak corresponding to lithium silicides shifts to higher binding energy because of the decrease of lithium content in lithium silicides, while the other species such as lithium silicates, lithium oxide, and lithium carbonate remained as irreversible species.