Lanthanum Oxyfluoride modifications boost the electrochemical performance of Nickel-rich cathode

Lanthanum oxyfluoride (LaOF) materials have appreciable higher conductivity, favorable thermal and chemical stability, herein the LaOF coating layer was synthesized on the cathode LiNi0.8Co0.1Mn0.1O2 through one-step solid-phase method, to study the effect of LaOF modification of the electrochemical performance. The modified sample 0.4LaOF-NCM exhibits the initial discharge capacity of 182.8 mAh·g−1 and the retention of 87.8% after 300 cycles at 1C and 2.8–4.3 V (half-cell, room temperature); meanwhile, its full cell has the capacity of 179.8 mAh·g−1 and the retention of 83.5% after 300 cycles, superior to the pristine NCM (175.8 mAh·g−1 and 79%, full cell). Through analyses of XRD, SEM, HRTEM and XPS test results, it indicates that the LaOF amorphous coating layer on the surface of the NCM material can inhibit the side reactions between the cathode and the electrolyte during the cycling, and consequently improve the cycling stability. After 100th cycles, the Li+ diffusion rate during the delithiation and lithiation process is 1.63 × 10−10 and 1.02 × 10−10 cm2 s−1 for the pristine NCM, whereas for the 0.4LaOF-NCM the Li+ diffusion rate is respectively 2.08 × 10−10 and 1.45 × 10−10 cm2 s−1, which are more than 1.3 times faster than those of the pristine NCM. It is suggested that such LaOF modification would have promising applications to improve the performance of LIB.