插层(化学)
氧气
阴极
化学
氧化还原
衰退
兴奋剂
纳米技术
化学工程
材料科学
光电子学
无机化学
频道(广播)
物理化学
电信
有机化学
工程类
计算机科学
作者
Weijin Kong,Jicheng Zhang,Deniz Wong,Wenyun Yang,Jinbo Yang,Christian Schulz,Xiangfeng Liu
标识
DOI:10.1002/anie.202112508
摘要
High-voltage LiCoO2 delivers a high capacity but sharp fading is a critical issue, and the capacity decay mechanism is also poorly understood. Herein, we clarify that the escape of surface oxygen and Li-insulator Co3 O4 formation are the main causes for the capacity fading of 4.6 V LiCoO2 . We propose the inhibition of the oxygen escape for achieving stable 4.6 V LiCoO2 by tailoring the Co3d and O2p band center and enlarging their band gap with MgF2 doping. This enhances the ionicity of the Co-O bond and the redox activity of Co and improves cation migration reversibility. The inhibition of oxygen escape suppresses the formation of Li-insulator Co3 O4 and maintains the surface structure integrity. Mg acts as a pillar, providing a stable and enlarged channel for fast Li+ intercalation/extraction. The modulated LiCoO2 shows almost zero strain and achieves a record capacity retention at 4.6 V: 92 % after 100 cycles at 1C and 86.4 % after 1000 cycles at 5C.
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