Internal and external bifunctional vanadium-modification strategy for LiNi0.80Co0.15Al0.05O2 cathode materials

LiNi(0.80)Co(0.15)Al(0.0)5O(2) (NCA) is widely used in Li-ion batteries due to its high reversible capacity and energy density. However, residual Li on the exterior of NCA suffers severe side reactions with air during preparation process, which destroy the surface of cathode material and cause irreversible capacity loss. This performance degradation has remained an issue that needs to be solved. Herein, a bifunctional modification strategy consisting of V doping and coating with Li3VO4 is reported to address this issue. V-doped and Li3VO4-coated NCA (VNCA) cathode materials were obtained using solid-phase method through one-step sintering. External Li3VO4 coating layer formed from the consumption of surface residual Li prevents the occurrence of interfacial adverse reactions. Furthermore, V doping stabilizes lattice structure. Obtained cathode material can improve the stability and rate capability of Li-ion batteries. 100-cycle cycle retention rate of VNCA coated with 2-M% Li3VO4 at 1C is 89.32%, which is significantly higher than that of NCA (67%). Additionally, specific discharge capacity of VNCA at 10C (145.6 mAh center dot g(-1)) is considerably higher than that of NCA (129.8 mAh center dot g(-1)).