Engineering oxygen vacancies in hierarchically Li-rich layered oxide porous microspheres for high-rate lithium ion battery cathode

Lithium-rich layered oxides always suffer from low initial Coulombic efficiency, poor rate capability and rapid voltage fading. Herein, engineering oxygen vacancies in hierarchically Li1.2Mn0.54Ni0.13Co0.13O2 porous microspheres (L@S) is carried out to suppress the formation of irreversible Li2O during the initial discharge process and improve the Li+ diffusion kinetics and structural stability of the cathode mateiral. As a result, the prepared L@S cathode delivers high initial Coulombic efficiency of 92.3% and large specific capacity of 292.6 mA h g−1 at 0.1 C. More importantly, a large reversible capacity of 222 mA h g−1 with a capacity retention of 95.7% can be obtained after 100 cycles at 10 C. Even cycled at ultrahigh rate of 20 C, the L@S cathode can deliver stable reversible capacity of 153 mA h g−1 after 100 cycles. Moreover, the full cell using L@S as cathode and Li4Ti5O12 as anode exhibits a relatively high reversible capacity of 141 mA h g−1 with an outstanding voltage retention of 97% after 400 cycles at a large current density of 3 C. These results may shed light on the improvement of electrochemical performances of lithium-rich layered oxides via the multiscale coordinated design based on atomic defects, microstructure and composition.