Surface modification of hollow microsphere Li1.2Ni1/3Co1/3Mn1/3O2 cathode by coating with CoAl2O4

Abstract

Li1.2Ni1/3Co1/3Mn1/3O2 was synthesized as a cathode material for lithium-ion batteries and coated with various amounts of CoAl2O4 (0–5 wt%) at high temperature. The effect of the surface modification on the structure and electrochemical performance of the cathode was evaluated. Microstructural analysis using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy revealed that the CoAl2O4 coating did not affect the crystal structure of the electrode material and that the coating only appeared on the electrode surface. The effect of the CoAl2O4 coating on the electrochemical performance was evaluated by examining charge-discharge cycles, rate performance, and electrochemical impedance. The cathodes coated with CoAl2O4 exhibited improved discharge capacity and cyclic performance compared with those of the uncoated cathode. The electrode coated with 2.5 wt% CoAl2O4 exhibited the highest discharge capacity (202.5 mAhg−1 vs. 185 mAhg−1 for the uncoated material) and highest capacity retention (84.8% for 50 cycles vs. 78.6% for the uncoated material).