Achieving CoAl2O4@Li1.2Ni0.13Co0.13Mn0.54O2 with Long Cyclic and High-Rate Performance via Citric Acid Combustion Method

Abstract

Lithium-rich manganese-based cathode materials (LNCM) have high specific capacities and operating voltages. However, they also have intractable deficiencies such as low capacity retention and unsatisfactory rate capability. Herein, CoAl2O4 with spinel structure and chemically stable is adopted to decorate the surface of LNCM to modify the cyclic and high-rate performance of final product. 3CoAl2O4@LNCM synthesized by self combustion of citric acid shows the best electrochemical properties such as lower voltage drop (4.7 mV per cycle) and higher capacity retention of 81.33% (1 C) after 100 cycles, which is exceed to bare LNCM (7.7 mV per cycle, 47.65%). Besides, the charge transfer resistance R ct of the modified sample is lower, and its lithium ion diffusion coefficient D Li + is higher. Consequently, 3CoAl2O4@LNCM is able to demonstrate high rate performance, whereby a capacity retention of 65.84% (5 C) is achieved after 100 cycles. The improved electrochemical properties of 3CoAl2O4@LNCM because of the 3D diffusion channel of CoAl2O4 benefits lithium ion diffusion; and the chemical stability of CoAl2O4 enhances the corrosion resistance of LNCM bulk to the electrolyte. As such, this results in the suppression of TM ion dissolution, and the enhancement of cyclic stability and initial coulomb efficiency.