NaF-Si-C-RGO杂化材料的制备及电化学性能

Preparation and electrochemical properties of NaF-Si-C-RGO hybrids

  • 摘要: 采用NaF溶液为添加剂,热固性酚醛树脂和还原氧化石墨烯(RGO)为碳源,制备了NaF-Si-C-RGO杂化材料。采用扫描电子显微镜、透射电子显微镜、热重分析仪、X射线衍射仪和拉曼分析仪等对其进行表征,并用作锂离子电池负极材料进行了相关电化学性能测试。NaF-Si-C-RGO杂化材料的循环稳定性和容量保持率均高于NaF-Si-RGO和Si-C-RGO杂化材料。因为硅纳米颗粒表面的无定形炭包覆层可以抑制SEI膜的不断形成;NaF中的Na+可以插入到氧化石墨烯片层中,不仅可以缓解氧化石墨烯片层的堆垛现象,还利于Si纳米颗粒在石墨烯片层中的分散,使更多的活性物发挥作用;F-的存在,一定程度抑制了电解液的分解,减少了HF的生成,这有利于维持电极结构的完整,从而保证了电极良好的循环稳定性。

     

    Abstract: NaF and Si nanoparticles and graphite oxide (GO) flakes were dispersed in a thermosetting phenolic resin (PR) in an aqueous solution, followed by drying and carbonization at 700℃ to produce NaF-Si-C-RGO hybrids. The structure of the hybrids was characterized by SEM, TEM, TGA, XRD and Raman spectroscopy. The electrochemical properties of the hybrids as anode materials of lithium ion battery were investigated and showed better electrochemical performance, larger reversible capacity and higher capacity retention when compared with both NaF-Si-RGO and Si-C-RGO hybrids. The amorphous carbon coating on the Si nanoparticles, derived from the PR, restricts the formation of a solid-electrolyte interface film. The Na+ in NaF is inserted between the GO layers, which not only alleviates the re-stacking of graphene sheets, but also improves the dispersion of Si nanoparticles in RGO layers, leading to a high utilization of active materials. F-also inhibits the decomposition of the electrolyte and the generation of HF, which is favorable for the cycle stability of the electrode.

     

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