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Revealing Mechanism of Li3PO4 Coating Suppressed Surface Oxygen Release for Commercial Ni-Rich Layered Cathodes
journal contribution
posted on 2020-07-17, 20:03 authored by Qingmeng Gan, Ning Qin, Zhenyu Wang, Zhiqiang Li, Youhuan Zhu, Yingzhi Li, Shuai Gu, Huimin Yuan, Wen Luo, Li Lu, Zhenghe Xu, Zhouguang LuSurface
modification through Li3PO4 (LPO)
coating is a brilliant approach to inhibit oxygen release of Ni-rich
layered Li[Ni0.8Co0.1Mn0.1]O2 (NCM811) cathodes, particularly under highly delithiated
states, which can help tackle the thermal runaway issue for industrial
applications. However, the mechanism of LPO prohibiting the release
of the oxygen from the surface of NCM811 is still unclear.
Herein we systematically investigate the critical role of the LPO
protective layer through combining atomic-scale microscopy and in/ex
situ techniques. In particular, results from electrochemical impedance
spectroscopy, galvanostatic intermittent titration technique test,
focused ion beam-high resolution transmission electron microscopy,
and in situ X-ray diffraction, unequivocally identifies that the LPO
layer can inhibit the transformation from layered-like to rock-salt-like
structure. Ex situ soft X-ray absorption spectroscopy and in situ
Raman further reveal the improved intensity of metal–oxide
bonds with the suppression of phase transition, thus inhibiting surface
oxygen release. This work provides inspiration for better understanding
of surface coating on stabilizing the Ni-rich cathodes.