Research progress on the surface/interface modification of high-voltage lithium oxide cathode materials

Lithium oxides are the most promising cathode candidates for high-performance lithium-ion batteries (LIBs), owing to their high theoretical capacity and average working voltage, which are conducive to achieving the ultimate goal of upgrading energy density. By raising the upper limit of the cutoff voltage, we may be able to further improve both the practical capacity and average voltage of lithium oxide cathodes. Unfortunately, the high-voltage operation of these cathodes results in significant challenges, namely, reduced surface structural stability and interfacial stability with electrolytes, thus degrading the electrochemical performance. Accordingly, surface/interface modification strategies, including surface coating, electrolyte regulation, binder design, and special surface treatments, are systematically summarized and comprehensively analyzed for high-voltage lithium oxide cathode materials in this review. Furthermore, the corresponding modification mechanisms are discussed in detail to better grasp the internal mechanisms for the enhanced electrochemical performance. Based on recent progress, we further propose predictable development directions for high-performance LIBs in future practical applications. This review provides new insights into various high-voltage lithium oxide cathodes and their universal surface/interface modification strategies towards advanced next-generation LIBs with high energy and power density and long cycle life.