Raising the charging cut‐off voltage of layered oxide cathodes can improve their energy density. However, it inevitably introduces instabilities regarding both bulk structure and surface/interface. Herein, exploiting the unique characteristics of high‐valence Nb 5+ element, a synchronous surface‐to‐bulk‐modified LiCoO 2 featuring Li 3 NbO 4 surface coating layer, Nb‐doped bulk, and the desired concentration gradient architecture through one‐step calcination is achieved. Such a multifunctional structure facilitates the construction of high‐quality cathode/electrolyte interface, enhances Li + diffusion, and restrains lattice‐O loss, Co migration, and associated layer‐to‐spinel phase distortion. Therefore, a stable operation of Nb‐modified LiCoO 2 half‐cell is achieved at 4.6 V (90.9% capacity retention after 200 cycles). Long‐life 250 Wh kg −1 and 4.7 V‐class 550 Wh kg −1 pouch cells assembled with graphite and thin Li anodes are harvested (both beyond 87% after 1600 and 200 cycles). This multifunctional one‐step modification strategy establishes a technological paradigm to pave the way for high‐energy density and long‐life lithium‐ion cathode materials.
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Yan et al. (2023) studied this question.