Tuning Co/O Redox Chemistry via Fermi Level Regulation for Stable High-Voltage LiCoO 2

作者：Mingpu Wen, Weijin Kong, Jicheng Zhang, Qinghua Zhang, Wen Yin, Nian Zhang, Ke Chai, Yang Yu, Huaican Chen, Xiangfeng Liu · 发表于：ACS Energy Letters · 年份：2022 · DOI：10.1021/acsenergylett.2c01841 · 被引用次数：31 · 研究领域：Advancements in Battery Materials、Supercapacitor Materials and Fabrication、Advanced Battery Materials and Technologies

LiCoO 2 (LCO) is ideal for 3C electronics due to its high tap density. However, the excessive O → Co charge transfer at high delithiation leads to irreversible Co reduction, O release, and structural degradation, deteriorating the high-voltage performance of LCO. Herein, we propose to regulate the intrinsic Fermi level via uneven trace Zr/Mg doping. First, the increase of electron density in the Fermi level mitigates both the O oxidation/coupled Co reduction through alleviating the O → Co charge transfer, restraining the formations of Co 2+ and O 2 . This elevates Co redox activity and reduces O redox activity. In addition, the structural evolution of the cathode at delithiation is simplified. The modulated LCO delivers a high discharge capacity and a high cycling stability with 4.5 and 4.6 V ceilings. This study sheds new light on the modulation of Co/O redox chemistry and the reliable large-scale production of high-voltage LiCoO 2 .