Effect of FePO_4 Coating on Performance of Li_(1.2)Mn-_(0.54)Ni_(0.13)Co_(0.13)O_2 as Cathode Material for Li-ion Battery

Li1.2Mn0.54Ni0.13Co0.13O2 with a rod-like morphology was prepared by a carbonate co-precipitation method followed by a high-temperature solid state reaction, and coated with different amounts of Fe PO4. XRD results and SEM images show that the particles of Li1.2Mn0.54Ni0.13Co0.13O2 are uniformly coated with amorphous Fe PO4. The amorphous Fe PO4 layer not only inhibits the reaction between Li1.2Mn0.54Ni0.13Co0.13O2 and electrolyte, but also acts as lithium ion receptor during the initial charging process. So, the surface modification of Li1.2Mn0.54Ni0.13Co0.13O2 with Fe PO4 reduces the initial irreversible capacity loss, and improves cyclic and rate performance. Specific electrochemical performance can be achieved by adjusting the amount of Fe PO4. Li1.2Mn0.54Ni0.13Co0.13O2 coated with 2wt% Fe PO4 exhibits the highest initial charge and discharge capacity, 325.9 and 258.4 m Ah/g at 0.05 C rate, respectively. The material coated with 4wt% Fe PO4 shows high discharge capacity and good cycle stability. And with the increase of Fe PO4 amounts, the initial coulombic efficiency increases greatly, reaching 97.4% for the sample coated with 20wt% Fe PO4.