Fabrication of all-solid-state lithium secondary batteries with amorphous TiS4 positive electrodes and Li7La3Zr2O12 solid electrolytes

Amorphous TiS4 (a-TiS4) thin film electrode was deposited on the garnet-type Li7La3Zr2O12 (LLZ) solid electrolyte pellet sintered at 1230 °C by the pulsed laser deposition method. The a-TiS4 electrode was dense and its thickness was ca. 400 nm and good contacts between the electrode and the electrolyte were obtained. All-solid-state cells of Li/LLZ/a-TiS4 operated as a lithium secondary battery at 25 °C, and showed reversible capacity of about 500 mAh per gram of a-TiS4 at 0.010 mA cm− 2 and good cycle performance for 15 cycles. Interfacial resistance between a-TiS4 electrode and LLZ electrolyte was almost constant during charge-discharge cycling. A pelletized LLZ was prepared with Li3BO3 at a lower sintering temperature of 900 °C, and the obtained LLZ-Li3BO3 pellet with the conductivity of 1.0 × 10− 4 S cm− 1 at 25 °C was applied to all-solid-state cells. The cells with LLZ-Li3BO3 and a-TiS4 also operated as a lithium secondary battery. The reversible capacity of the cells using LLZ-Li3BO3 was about 480 mAh per gram of a-TiS4 at a current density of 0.020 mA cm− 2.