Solution Processing of Lithium-Rich Amorphous Li-La-Zr-O Ion Conductor and Its Application for Cycling Durability Improvement of LiCoO₂ Cathode as Coating Layer

Lithium-rich amorphous Li-La-Zr-O (a-Li-La-Zr-O) electrolyte is successfully synthesized using sol–gel processing method. With unlimited compositions of the amorphous structure, lithium-rich compositions are systematically investigated to determine optimal composition and optimized processing conditions of a-Li-La-Zr-O coatings. There is an improvement in ionic conductivity of a-Li-La-Zr-O with Li content increasing, specifically from 3.0 × 10⁻⁸ S cm⁻¹ (Li₈La₂Zr₂O₁₁) to 1.18 × 10⁻⁶ S cm⁻¹ (Li₁₈La₂Zr₂O₁₆), thereby resulting in low activation energy. The high-ionic-conductivity a-Li-La-Zr-O is implemented as an artificial solid electrolyte interface coating layer on cathode materials. The a-Li-La-Zr-O-coated LiCoO₂ (LCO) and LiNi_0.8Mn_0.1Co_0.1O₂ (NMC 811) coin cells exhibit better cycling performance than the bare coin cell at the optimum compositional ratio of a-Li-La-Zr-O. A-Li-La-Zr-O can be a promising material for solid electrolyte battery and a potential coating layer for the modification of cathode surface.