Comparative Study of TiS2/Li-In All-Solid-State Lithium Batteries Using Glass-Ceramic Li3PS4 and Li10GeP2S12 Solid Electrolytes

Abstract

A systematic investigation on the electrochemical performances of all-solid-state TiS2/Li-In cells with various configurations using glass-ceramic Li3PS4 (LPS) and Li10GeP2S12 (LGPS) solid electrolytes is presented. In spite of the superior conductivity of LGPS to that of LPS, LGPS shows poor stability in the low voltage range below ∼1 V (vs. Li/Li+) as evidenced by cyclic voltammetry (CV) and ex-situ XRD experiments. The combined use of the LGPS cathode layer and an LGPS-LPS SE bilayer where LPS forms an interface with the Li-In anode ((TiS2-LGPS)/(LGPS-LPS)/Li-In cell) results in the best overall performance at 30 °C, exhibiting a capacity of ∼60 mA h g?1 (∼25% of the theoretical capacity) at 20C, over a voltage range of 1.5?3.0 V (vs. Li/Li+). Combined analyses by electrochemical impedance spectroscopy (EIS) and conductivity measurements of the cathode layers highlight the importance of having an SE of high conductivity and optimizing the structure of the composite electrode.