掺杂金属对天然鳞片石墨电化学嵌/脱锂性能的影响

研究化学镀Ni、Cu和混合掺杂Zn处理后天然鳞片石墨的电化学嵌/脱锂性能。结果表明:金属微粒Ni、Cu与Zn的掺入可有效改善天然鳞片石墨的循环性能与大倍率充放电特性,金属微粒有效降低石墨电极内阻、保证石墨颗粒之间紧密的电接触是掺入金属微粒后石墨大倍率充放电性能得到改善的重要原因之一。Ni与Cu微粒改善石墨循环性能的机理与Zn的不同,Cu、Ni通过阻止溶剂化锂离子嵌入维持石墨结构稳定性,来达到提高材料循环性能的目的;金属Zn改善石墨循环性能的原因则可能是嵌锂过程中,Zn锂化所形成Li-Zn合金维持材料表面所形成SEI膜的稳定性。

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.