Improving the electrochemical performance of LiNi0.6Co0.1Mn0.3O2 cathode at high cutoff voltage by dual functions of Y(PO3)3 modification

Abstract Layered nickel-rich ternary materials LiNixCoyMn1-x-yO2 have been deemed as the most practical candidates in the power battery industry on account of their high capacity and low cost. In the study, we investigated the modifying impacts of Y(PO3)3 on structure and electrochemical properties of LiNi0.6Co0.1Mn0.3O2 (NCM613) material. The characterization results show that trace amounts of yttrium may be incorporated into the crystals of NCM613 material, and the remaining Y(PO3)3 reacted with the surface residual lithium to produce a hybrid YPO4-Li3PO4-Y(PO3)3 coating layer on the surface of NCM613 grains. The modified-NCM613 with 0.3 wt% Y(PO3)3 presents high initial discharge specific capacities of 181.3 mAh g−1 and 196.0 mAh g−1 in 2.8–4.5 V (vs Li/Li+) at 1C under 25 °C and 45 °C, and maintains 87.2% and 82.1% retentions after 100 cycles, higher than those of the unmodified NCM613 (71.8% and 65.8%). The improved electrochemical performance of 0.3 wt% Y(PO3)3 modified-NCM613 results from dual functions of Y3+ doping and the hybrid YPO4-Li3PO4-Y(PO3)3 coating. The Y3+ doping can improve lithium ion diffusion rate and promote the layered structural stability. The hybrid coating suppresses the corrosion of electrolyte to the cathode material in cycles.