High potential performance of Cerium-doped LiNi0.5Co0.2Mn0.3O2 cathode material for Li-ion battery

Abstract

To enhance the electrochemistry performance of LiNi0.5Co0.2Mn0.3O2 (NCM-523) cathode material, especially at high rate and high potential charge–discharge, Cerium has been used to dope into the material. Cerium-doped NCM-523 exhibits significantly better rate capability and excellent cycling stability than the pristine material both at conventional potential of 4.25 V and high potential of 4.5 V. Electrochemical tests show that Cerium-doped NCM-523 discharged a 2.56 times higher capacity than pristine sample at 5 C when charged to 4.5 V, versus 1.94 times at 4.25 V. Pristine NCM-532 exhibits the capacity retention of 93.28 and 90.90 % at 1 C after 30 cycles for 4.25 and 4.5 V, respectively. After doping with Cerium, the capacity retention is increased to 96.77 and 97.35 % after cycles. XRD results show that Cerium is successfully doped into LiNi0.5Co0.2Mn0.3O2 crystal lattice. Such enhanced performance of material should be ascribed to Cerium doping, which stabilizes the layered crystal structure, reduces the dissolution degree of cation in the electrode and improves the lithium-ion diffusion of the oxide proved by the EIS tests.