Authors: Tongtong Shang, Dongdong Xiao, Fanqi Meng, Xiaohui Rong, Ang Gao, Ting Lin, Zhexin Tang, Xiaozhi Liu, Xinyan Li, Qinghua Zhang, Yuren Wen, Ruijuan Xiao, Xuefeng Wang, Dong Su, Yong-Sheng Hu, Hong Li, Qian Yu, Ze Zhang, Vaclav Petricek, Lijun Wu, Lin Gu, Jian-Min Zuo, Yimei Zhu, Ce-Wen Nan, Jing Zhu
Published: 2022-10-03
DOI: 10.1038/s41467-022-33595-0
Source: Full article
AbstractThe operation of lithium-ion batteries involves electron removal from and filling into the redox orbitals of cathode materials, experimentally probing the orbital electron population thus is highly desirable to resolve the redox processes and charge compensation mechanism. Here, we combine quantitative convergent-beam electron diffraction with high-energy synchrotron powder X-ray diffraction to quantify the orbital populations of Co and O in the archetypal cathode material LiCoO2. The results indicate that removing Li ions from LiCoO2 decreases Co t2g orbital population, and the intensified covalency of Co–O bond upon delithiation enables charge transfer from O 2p orbital to Co eg orbital, leading to increased Co eg orbital population and oxygen oxidation. Theoretical calculations verify these experimental findings, which not only provide an intuitive picture of the redox reaction process in real space, but also offer a guidance for designing high-capacity electrodes by mediating the covalency of the TM–O interactions.