ALL-SOLID-STATE LITHIUM SECONDARY, BATTERIES USING SULFIDE-BASED GLASS CERAMIC ELECTROLYTES

Abstract

Highly conductive glass-ceramic electrolytes are successfully prepared in the system Li 2 S - P 2 S 5 with 70 and 80 mol% Li 2 S . The conductivities of these electrolytes are respectively 3.2 × 10-3 and 1.0 × 10-3 S cm -1 at room temperature. The precipitated crystals upon heat treatment of the glass are new superionic phase Li 7 P 3 S 11 and thio-LISICON II analog Li 3+5x P 1-x S 4, respectively. The crystal structure of the new phase Li 7 P 3 S 11 is analyzed and found to have a triclinic unit cell with space group of P-1 and to contain [Formula: see text] and [Formula: see text] ions. All-solid-state batteries using the Li 2 S - P 2 S 5 glass-ceramics are fabricated in order to evaluate the cell performance as a lithium secondary battery. The cells In /80 Li 2 S ·20 P 2 S 5 (mol%) glass-ceramic/ LiCoO 2 exhibit excellent cycling performance of over 500 times with no decrease in the discharge capacity (100 mAh g-1) at limited current densities. They also worked under very high current densities of 10 mA cm-2 when oxide- or sulfide-coated LiCoO 2 particles were used as an active material.