Effect of Voltage Range and BiPO ₄ Coating on the Electrochemical Properties of LiNi _0.8 Co _0.15 Al _0.05 O ₂

Abstract

Abstract BiPO 4 ‐coated LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathode material is prepared by a precipitation method. Scanning electron microscope and X‐ray diffraction results demonstrate that the morphology and structure of NCA are not affected by BiPO 4 layer. Transmission electron microscopy analysis indicates that the thickness of the layer is about 10 nm. Electrochemical properties of NCA and BiPO 4 ‐coated NCA are investigated in different voltage ranges. The results show that the wider the charge and discharge cut‐off voltage is, the larger the specific capacity is, with the initial discharge capacity of 325.0 mAh g −1 within the voltage of 1.5‐4.8 V. The most significant discovery is the charge platform at 2.3‐2.5 V and the discharge platform at around 1.7 V, which accounts for the high capacity properties of NCA. Furthermore, the existence of BiPO 4 coating helps to enhance the cycle performance of NCA.