Surface heterostructure induced by TiO2 modification in Li-rich cathode materials for enhanced electrochemical performances

Building stable interfacial structure is highly desirable for high-voltage lithium rich cathode materials for lithium ion batteries. Heterostructure interface should play a crucial role in controlling electrochemical performances of Li-rich oxides. Herein, Li1.2Ni0.13Co0.13Mn0.54O2 nanoparticles are massively prepared via a facile ultrasonic spraying method, followed by surface-modification with TiO2 ultrathin layer using low-temperature hydrolysis technique. Comparing to pristine Li1.2Ni0.13Co0.13Mn0.54O2, TiO2-coated composites exhibit better electrochemical performances in terms of rate capability, cycling stability and thermal stability. Li1.2Ni0.13Co0.13Mn0.54O2@TiO2 composites deliver a reversible discharge capacity of 194.9 mAh▪g−1 at 25 °C and 257.8 mAh▪g−1 at 55 °C after 100 cycles, while the pristine Li1.2Mn0.52Ni0.13Co0.13O2 only has a discharge capacity of 208.4 mAhg−1 and 253.9 mAhg−1 respectively. The TiO2-coating could reduce the work function of the hybrid composites and efficiently suppress the evolution of a solid electrolyte interface film at the electrode/electrolyte as well as improve thermal stability. Moreover, the built-in electric field originating from the difference in work function at the hetero-junction interface, would also facilitate electron-transfer and Li-ion migration across the hetero-junction interface and consequently robust electrochemical performances.