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Stablization of Lattice Oxygen in Li-Rich Mn-Based Oxides via Swing-like Non-Isothermal Sintering
Yu-Han Zhang, Ding Zhang*, Lin-Rong Wu, Jun Ma*, Qun Yi, Zhaoxiang Wang, Xuefeng Wang, Zhen Wu, Chu Zhang, Naifang Hu, Shu-Chih Haw, Jin-Ming Chen, Zhiwei Hu*, and Guanglei Cui*
Redox from the holes at the O 2p orbitals is a well-known phenomenon in Li-rich Mn-based batteries. However, such an anionic redox process results in the formation of O2, leading to structural instability owing to unstable O 2p holes. Herein, a swing-like non-isothermal sintering technique is used to stabilize the lattice oxygen by suppressing the formation of O2 during charging. It reduces both the number of intrinsic oxygen vacancies of the Li-rich Mn-based oxides and the formation of O2 during charging as compared with traditional constant high-temperature sintering. Consequently, the number of holes generated during charging in the O 2p orbitals increases, whereas the number of unstable O 2p holes forming O2 decreases. Therefore, the sample Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 prepared via swing-like non-isothermal sintering exhibited considerably slower voltage fading and better cycling stability. This study provides valuable guidelines for stabilizing the lattice oxygen and improving the structural stability of the oxide cathodes for electrochemical energy storage. This paper was co-published by research team of Dr. Guanglei Cui (Qingdao Industrial Energy Storage Research Institute), Dr. Zhiwei Hu (Max-Planck Institute for Chemical Physics of Solids, Germany), and Dr. Jin-Ming Chen (NSRRC).