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Approaching the capacity limit of lithium cobalt oxide in lithium ion batteries via lanthanum and aluminium doping

2018; Nature Portfolio; Volume: 3; Issue: 11 Linguagem: Inglês

10.1038/s41560-018-0180-6

2058-7546

Qi Liu, Xin Su, Dan Lei, Yan Qin, Jianguo Wen, Fangmin Guo, Yimin A. Wu, Yangchun Rong, Ronghui Kou, Xianghui Xiao, Frédéric Aguesse, Javier Bareño, Yang Ren, Wenquan Lu, Yangxing Li,

Advanced Battery Technologies Research

Lithium cobalt oxides (LiCoO2) possess a high theoretical specific capacity of 274 mAh g–1. However, cycling LiCoO2-based batteries to voltages greater than 4.35 V versus Li/Li+ causes significant structural instability and severe capacity fade. Consequently, commercial LiCoO2 exhibits a maximum capacity of only ~165 mAh g–1. Here, we develop a doping technique to tackle this long-standing issue of instability and thus increase the capacity of LiCoO2. La and Al are concurrently doped into Co-containing precursors, followed by high-temperature calcination with lithium carbonate. The dopants are found to reside in the crystal lattice of LiCoO2, where La works as a pillar to increase the c axis distance and Al as a positively charged centre, facilitating Li+ diffusion, stabilizing the structure and suppressing the phase transition during cycling, even at a high cut-off voltage of 4.5 V. This doped LiCoO2 displays an exceptionally high capacity of 190 mAh g–1, cyclability with 96% capacity retention over 50 cycles and significantly enhanced rate capability. Lithium cobalt oxides are used as a cathode material in batteries for mobile devices, but their high theoretical capacity has not yet been realized. Here, the authors present a doping method to enhance diffusion of Li ions as well as to stabilize structures during cycling, leading to impressive electrochemical performance.