Electrochemical Properties of the LiNiCoMnO Cathode Material Modified by Lithium Tungstate under High Voltage.

An amount (5 wt %) of lithium tungstate (LiWO) as an additive significantly improves the cycle and rate performances of the LiNiCoMnO electrode at the cutoff voltage of 4.6 V. The 5 wt % LiWO-mixed LiNiCoMnO electrode delivers a reversible capacity of 199.2 mA h g and keeps 73.1% capacity for 200 cycles at 1 C. It retains 67.4% capacity after 200 cycles at 2 C and delivers a discharge capacity of 167.3 mA h g at 10 C, while those of the pristine electrode are only 44.7% and 87.5 mA h g, respectively. It is shown that the structure of the LiNiCoMnO cathode material is not affected by mixing LiWO. The introduced LiWO effectively restrains the LiPF and carbonate solvent decomposition by consuming PF at high cutoff voltage, forming a stable cathode/electrolyte interface film with low resistance.