Operando and Ex-situ Raman Spectroscopies for Evaluating Carbon Structural Changes in Anode-Free-Type Sulfide-Based All-Solid-State Li Battery

Abstract

Anode-free-type sulfide-based all-solid-state Li batteries are possible candidates to achieve high energy density and cycle capability because of their high ionic conductivity and light weight. Recently, the Ag/C layer introduced between the solid electrolyte and the current collector promotes the stable deposition and dissolution of metallic Li during the charge, its role in the charge-discharge reactions, however, have been unclear. In this study, we applied Operando / ex-situ Raman spectroscopy to observe the cross section of the all-solid-state battery to reveal the morphology and structural changes in the Ag/C layer. The obtained Raman spectra revealed that the D- and G-bands derived from carbon black changed the peak shapes and positions, suggesting that structural changes occurred in the Ag/C layer during the charge-discharge processes. Additional peaks also appeared during the charge that were related to the alloying reactions of Ag and Li.