Effect of metal particles on electrochemical intercalation/deintercalation Li performances of natural flake graphite

The intercalation/deintercalation Li performances of natural flake graphite (NFG) doped with metal particles, such as Ni, Cu and Zn, were studied. The experimental results show that the metal particles are effective to improve cycling behavior and rate performance of NFG. One of the main reasons for these phenomena is that the metal particles can effectively reduce the graphite electrode resistance and accordingly ensure intimate contact between graphite particles. The mechanism of that Ni and Cu can improve the cycling behavior of NFG is different from that of Zn. The electroless Ni and Cu on the surface of graphite can effectively prevent the intercalation of solvated Li ion and maintain the structure stability of graphite, thus improve the cycling behavior. The reason that Zn doping improves cycling behavior of graphite is probably for the formation of Zn-Li alloy from the Zn lithiation reaction during the intercalation process which is beneficial to form stable SEI film on the surface of carbon electrode.