A solid-state Li-ion conductor of Li1.3Al0.3Ti1.7(PO4)3 was synthesized according to previous reports. 23−25 Stoichiometric amounts of Li2CO3, Al2O3, TiO2, and(NH4)H2PO4 were ball-milled in ethanol for 30 min and then dried by distillation; the dried powder was heated at 400 °C for 2 h to release volatile products before the temperature was raised to 800 °C and held at that temperature for 2 h in air. The obtained LATP was ball-milled to ∼50 μm, and the powder was cold-pressed into sheets and sintered at 800 °C for 4 h in air. The thickness of the obtained LATP sheets was measured to be around 300 μm, and the diameter was 1.8 cm.