Low-Resistive LiCoO₂/Li_1.3Al_0.3Ti₂(PO₄)₃ Interface Formation by Low-Temperature Annealing Using Aerosol Deposition

Interfacial resistance at electrode-high Li⁺ conductive solid electrolytes must be reduced well to develop high-power all-solid-state batteries using oxide-based solid electrolytes (Ox-SSBs). Herein, crystalline electrode films of LiCoO₂ (LCO) are formed on a high Li⁺ conductive crystalline-glass solid electrolyte sheet, Li_1.3Al_0.3Ti₂(PO₄)₃ (LATP) (σ_{25 °C} = 1 × 10⁻⁴ S cm⁻¹), at room temperature by aerosol deposition (AD), and the effects of the annealing temperature on the interfacial resistivities (R_int) at the LCO/LATP are investigated. The R_int visibly increases by annealing over 500 °C with the growth of Co₃O₄ as a reactant. In contrast, R_int is reduced to ≈100 Ω cm² by low-temperature annealing at 250–350 °C due to superior contact through the structural rearrangement of an artificial metastable interface formed by the AD. These results are applied to bulk-type Ox-SSB, Li/Li₇La₃Zr₂O₁₂(LLZ)/LCO–LATP, and our best Ox-SSB delivers a discharge capacity of 100 mA cm⁻² at 100 °C.