A new route for graphene wrapping LiVPO4F/C nano composite toward superior lithium storage property

作者：Liu, Zhaomeng; Peng, Wenjie^*; Fan, Yulei; Li, Xinhai; Wang, Zhixing; Guo, Huajun; Wang, Jiexi

来源：Journal of Alloys and Compounds, 2015, 639: 496-503.

DOI：10.1016/j.jallcom.2015.03.207

• Composite materials
• Energy storage materials
• LiVPO4F
• Cathode
• Graphene
• Lithium ion battery

To enhance the electronic conductivity of LiVPO4F, graphene-decorated LiVPO4F/C nano composites were prepared via a solution route followed by low-temperature calcination. XRD results reveal that the crystal structure of LiVPO4F/C with graphene wrapping remains unchanged. SEM and TEM images demonstrate that the as-synthesized graphene modified particles tend to become smaller and are dispersed uniformly into the graphene layers. The graphene sheets stretch out and cross-link into a conducting network around the LiVPO4F particles, resulting in improved electronic conductivity and enhanced electrolyte permeability. SAED patterns confirmed the presence of graphene, as well as crystalline nature of LiVPO4F with clear lattice structure and sharp diffraction spots. When applied as cathodes for lithium ion batteries, the graphene wrapped LiVPO4F/C nano composites exhibit better cycle ability and rate capability than the pristine one. Particularly, the sample prepared by using 60 mL graphene oxide dispersion demonstrates a superior rate capability with a discharge capacity of 117 mA h g (1) at 8 C, as well as excellent cycling stability, maintaining 83.7% capacity retention after 350 cycles at 8 C. CV and EIS tests separately indicate that the graphene modified samples possess lower polarization and faster charge transfer than the bare sample.

• 单位
  中南大学