Applied Surface Science, Vol.484, 21-32, 2019
Studies on electrochemical reversibility of lithium tungstate coated Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode material under high cut-off voltage cycling
In order to enhance the storage performance and electrochemical reversibility of the Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode material at high cut-off voltage (4.6 V), the surface coating layer of lithium tungstate (Li2WO4) is successfully prepared via a one-step synthesis way followed with a high temperature calcination method. After 500 cycles at 2C in 2.8-4.6 V, the capacity retention of the modified material is improved from 26.95% to 60.62%, and the average discharge voltage can remain at 3.62 V, which is 0.32 V higher than that of the original sample. In addition, after stored in air for 60 days, the discharge capacity of the modified sample still maintains 146 mA h g(-1) after 100 cycles at 1C, which has 36% increase than that of the pristine sample. These results are attributed to the fact that the Li2WO4 coating can reduce the interfacial polarization, and enhance Li-ion diffusion and surface stability by suppressing the decomposition of electrolyte on cathode materials with high oxidation surface at high cut-off voltage (4.6 V).
Keywords:Lithium tungstate;High cut-off voltage;LiNi0.8Co0.1Mn0.1O2 cathode material;Surface coating;Electrochemical reversibility