One-step construction of oxygen vacancies and coating to improve lithium storage performance of Li-rich layered oxides

With the advantages of higher capacity and lower price, Li-rich layered oxides have tremendous potential to become an advanced cathode material in the next generation Li-ion batteries (LIBs). Nevertheless, the commercialization of Li-rich layered oxides is seriously hindered by the large initial non-reversible capacity loss, inferior rate performance, capacity and voltage decay. Herein, a multi-strategy synergistic Li1.2Ni0.13-Co0.13Mn0.54O2 (LRNCM) sample was prepared by the simultaneous establishment of oxygen vacancies and Nb2O5/C coating by C10H5NbO20.xH2O pyrolysis. The oxygen vacancies on the surface inhibit irreversible O-2 release and promote the diffusion of Li+ ions, while the well-stabilized Nb2O5/C coating alleviates the corrosion of electrolytes. As a result, the initial coulombic efficiency (ICE) is increased from 60.41% to 76.95%. The capacity retention is improved from 80.6% to 86.8% after 100 cycles at 0.5 C, and the high-rate performance increases from 87 mAh g(-1) to 144.6 mAh g(-1) at 10 C. This work shows that the synergistic effect of oxygen vacancies and Nb2O5/C coating on LRNCM can effectively improve the charge/discharge reversibility, cycle stability and rate performance.