Enhanced electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode at high cutoff voltage by modifying electrode/electrolyte interface with lithium metasilicate

Developing high-voltage Li ion batteries (LIBs) is an important trend to meet the requirement of high energy density battery . However, high voltage will cause a series of problems harming the cycle performance of LIBs at the same time. This work is to investigate the effect of inorganic substance Li 2 SiO 3 on the electrochemical performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathode at high cutoff voltage of 4.6   V. XRD result shows that the structure of NCM622 cathode material is not affected by mixing Li 2 SiO 3 . However, XPS and EIS tests indicate that Li 2 SiO 3 has an evident influence on suppressing the decomposition of LiPF 6 and carbonate solvents at high voltage, reducing interfacial solid film impedance and modifying electrode/electrolyte interface. In addition, Li 2 SiO 3 retards the transition metal dissolution by consuming HF. Therefore, it enhances the electrochemical properties of the NCM622 cathode significantly. The highest discharge capacity increases to 191.7   mA   h   g -1 by mixing Li 2 SiO 3 , compared with the value of 180   mA   h   g -1 in the case of NCM622 cathode. The NCM622 electrode mixed with Li 2 SiO 3 also exhibits a better capacity retention of 73.4% after 200 cycles and a high rate capability at 20C with the value of 89   mA   h   g -1 , in contrast with 62.2% and 31   mA   h   g -1 attained in the NCM622 cathode.