LiNbO3 and LiTaO3 Coating Effects on the Interface of the LiCoO2 Cathode: A DFT Study of Li-Ion Transport

In solid-state batteries, the interface between cathodes and solid electrolytes is crucial and coating layers play a vital role. LiNbO₃ has been known as a promising coating material, whereas recent studies showed its degradation via releasing oxygen and lithium during cycling. This computational study addresses the elucidation of essential characteristics of the coating materials by examining LiNbO₃ and its counterpart LiTaO₃ interfaces to a representative layered cathode, LiCoO₂. Employing the interface CALYPSO method, we constructed explicit models of both coatings on LiCoO₂. Our findings indicate that LiTaO₃ offers easier Li⁺ migration at the interface due to the smaller difference in Li adiabatic potential at the interface, whereas LiNbO₃ more effectively suppresses oxygen activity at high delithiation states via lowering the O 2p states. This comparative analysis provides essential insights into optimizing coating materials for improved battery performance.