Effect of Preparation Methods on the Electrochemical Performance of All-solid-state Li-S Batteries

All-solid-state Li-S batteries were fabricated with lithium silicide anodes (Li4.4Si), sulfide-based glass electrolyte (Li2S-P2S5), and a sulfur composite cathode. The sulfur based composite cathode was prepared using two methods; (Case 1) mortar-mixing and (Case 2) planetary ball milling at a rotation speed of 370 rev/min for 15 min. SEM analysis results indicated that the 'Case 2' method improved the distribution of sulfur, carbon and solid electrolyte particles, with a reduction in particle size. This effect was reflected in impedance spectra, and eventually in charge-discharge capacity: the electrode/electrolyte interface resistance was reduced so that the average charge-discharge capacities increased with the 'Case 2' cathode. Thus, the present work indicates the method of preparing the sulfur composite cathode profoundly affects the performance of solid state Li-S batteries.