Yan, Y.; Fang, Q.; Kuai, X.; Zhou, S.; Chen, J.; Zhang, H.; Wu, X.; Zeng, G.; Wu, Z.; Zhang, B.; Tang, Y.; Zheng, Q.; Liao, H.-G.; Dong, K.; Manke, I.; Wang, X.; Qiao, Y.; Sun, S.-G.: One-Step Surface-to-Bulk Modification of High-Voltage and Long-Life LiCoO2 Cathode with Concentration Gradient Architecture. Advanced Materials 36 (2024), p. 2308656/1-9
10.1002/adma.202308656
Abstract:
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 Nb5+ element, a synchronous surface-to-bulk-modified LiCoO2 featuring Li3NbO4 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 LiCoO2 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.