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

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