TiO<sub>2</sub> Anode Material for All-Solid-State Battery Using NASICON Li<sub>1.5</sub>Al<sub>0.5</sub>Ge<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> as Lithium Ion Conductor

We have been developing sintered multilayer oxide-based all-solid-state batteries. Anode active material rutile-type TiO2 was not reacted with amorphous Na superionic conductor (NASICON)-type solid electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) even after sintered at 600 °C in a nitrogen atmosphere from the XRD patterns. The charge/discharge behavior of the electrochemical measuring cell (when using a non-aqueous electrolyte) was not different from that of rutile-type TiO2. However, anatase-type TiO2 charge/discharge behavior changed after sintering process. Additionally, in the result of the input/output characteristics using multilayer oxide-based all-solid-state battery, rutile-type TiO2 as anode material was 3 times higher discharge capacity than anatase-type TiO2 at current value 25.6 µA mm−2. Finally, we successfully measured the Raman spectroscopy of all-solid-battery and rutile-type TiO2 Raman shift peaks were reversibility during charge/discharge. Based on these findings, we conclude that rutile-type TiO2 maintained a strong crystalline structure and high Li diffusivity even when sintered with amorphous LAGP. It suggested that rutile-type TiO2 is suitable as anode material for oxide-based all-solid-state batteries requiring the sintering process.