Stability of amorphous Li-La-Zr-Ta-O coating for high-voltage cathodes in sulfide-based solid-state batteries

Abstract

Nickel-rich high-voltage cathodes require a protective layer to suppress chemical reactions and to increase stability in sulfide-based solid-state batteries. Garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) can serve as a protective layer for cathodes because of its high Li-ion conductivity and low electron transferability. To crystallize LLZTO on the cathode surface, high thermal treatment (>700 °C) is necessary, which invariably leads to interdiffusion of elements, and consequent detrimental interface degradation. For this work, we proposed an amorphous LLZTO coating for LiNi0.5Co0.2Mn0.3O2 cathode particles and investigated the stability of the interface at a full charge (4.55 V vs. Li/Li+) state with an argyrodite sulfide-based solid-state battery.