Improving the electrochemical performance of Ni-rich cathode material LiNi0.815Co0.15Al0.035O2 by removing the lithium residues and forming Li3PO4 coating layer

Ni-rich cathode materials always suffer from surface lithium residues mainly caused by the reduction of Ni3+ to Ni2+ when exposing to moisture, and severe side reactions between organic electrolyte and highly active Ni4+ when fully charged. An appropriate amount of NH4H2PO4 is firstly coated on the...

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Bibliographic Details
Published in:	Journal of alloys and compounds 2017-02, Vol.693, p.1157-1163
Main Authors:	Tang, Zhong-Feng, Wu, Rong, Huang, Pei-Feng, Wang, Qing-Song, Chen, Chun-Hua
Format:	Article
Language:	eng
Subjects:	Ammonium phosphate Li-ion battery Lithium nickel cobalt aluminum oxide Surface lithium Thermal stability
Online Access:	Get full text
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Summary:	Ni-rich cathode materials always suffer from surface lithium residues mainly caused by the reduction of Ni3+ to Ni2+ when exposing to moisture, and severe side reactions between organic electrolyte and highly active Ni4+ when fully charged. An appropriate amount of NH4H2PO4 is firstly coated on the hydroxide precursor Ni0.815Co0.15Al0.035(OH)2 before mixing with Li2CO3. The NH4H2PO4 can react with the lithium residues and form a uniform Li3PO4 coating layer. X-ray diffraction, scanning electron microscopy, field emission transmission electron microscopy and element mapping are employed to investigate the Li3PO4 coating layer. Electrochemical measurements results show that the cycle stability of the synthesized LiNi0.815Co0.15Al0.035O2 both at room temperature and 55 °C has been significantly improved. Its thermal stability has also been greatly enhanced. •NH4H2PO4 can remove lithium residues and form a uniform Li3PO4 coating layer.•Porous Li3PO4 coating layer suppresses side reactions.•The thermal stability of Ni-rich cathode materials can be significantly enhanced.
ISSN:	0925-8388 1873-4669