Improved high rate capability of Li[Li0.2Mn0.534Co0.133Ni0.133]O2 cathode material by surface modification with Co3O4

Abstract

High capacity Li- and Mn-rich layered oxides are of particular interest as cathode materials for lithium-ion batteries, but large initial irreversible capacity, inferior poor cycle stability and rate capability greatly limited large-scale commercial application. In this work, we propose an effective strategy via surface modification of Co3O4 on surface of Li[Li0.2Mn0.534Co0.133Ni0.133]O2 (LMCNO) to improve the electrochemical performance. In comparison with pristine LMCNO, all the Co3O4-modified LMCNO composites show higher capacity, better cycling stability and rate capability. Among them, 1.5 wt% Co3O4-modified LMCNO shows high initial capacity of 253.3 mA h g−1, good capacity retention of 73.3% after 80 cycles at 0.2C and much improved rate capability especially at high rates. The enhanced electrochemical properties can be attributed to protecting LMCNO bulk materials from the electrolyte attack by Co3O4 surface layer as well as its high ionic/electronic conductivity. Electrochemical impedance spectroscopy reveals that the Co3O4-modified LMCNO sample shows much smaller charge transfer resistance than pristine sample.