Preparation and electrochemical characteristics of Co3(PO4)2-coated LiNi0.8Co0.2O2 by solid-state reaction at room temperature

LiNi0.8Co0.2O2 particles were modified by Co3(PO4)2 coating. The effects of the Co3(PO4)2 coating on the structure and electrochemical properties of the LiNi0.8Co0.2O2 cathode material were investigated. The Co3(PO4)2 coating forms a thin layer on the surface of the LiNi0.8Co0.2O2material and a solid solution by interacting with the LiNi0.8Co0.2O2 core material during calcination at 700°C for 4 h. Charge-discharge experiment results show that the Co3(PO4)2 coating improves the cycling stability of the LiNi0.8Co0.2O2 cathode material. The capacity retention of the pristine LiNi0.8Co0.2O2 cathode after 50 cycles is 83.6%, whereas it is 91.7% in the case of the LiNi0.8Co0.2O2 cathode coated with 1 wt.% Co3(PO4)2. Storage tests of the 4.35 V charged electrode at 60°C after a month show that the Co3(PO4)2-coated sample exhibits good storage properties compared with the pristine sample.