石墨烯包封Na3V2(PO4)3用作钠离子电池负极材料的电化学性能探究

具有三维网络结构的NASICON型Na₃V₂(PO₄)₃材料,由于其稳定的电压平台,较高的理论容量（117 mA?h/g),被视为一种具有良好应用前景的钠离子电池负极材料。采用溶剂热和进一步热处理的方式,获得石墨烯包封Na₃V₂(PO₄)₃的复合材料Na₃V₂(PO₄)₃/G],有效提高了Na₃V₂(PO₄)₃的电子导电性。在0.01 ~ 3.00 V电压区间,0.2 C倍率进行测试时,Na₃V₂(PO₄)₃/G复合材料在230圈循环后,其放电比容量保持在100.9 mA?h/g,容量保持率高达68.4%,即使在5 C倍率,其放电比容量仍可达65.2 mA?h/g。然而,纯相Na₃V₂(PO₄)₃的放电比容量仅为47.4 mA?h/g,容量保持率仅为44.7%,在5 C倍率时,其放电比容量仅为25.1 mA?h/g,证实石墨烯包封结构能显著提升Na₃V₂(PO₄)₃的循环稳定性和倍率性能。

Electrochemical Performance Investigation of Graphene Wrapped Na3V2(PO4)3 as Anode Material for Sodium Ion Battery

NASICON-type Na₃V₂(PO₄)₃ with three-dimensional network structure is regarded as a promising electrode material for sodium ion batteries (SIBs) anode due to its stable voltage platform and high theoretical capacity (117 mA?h/g). In this work, the graphene wrapped Na₃V₂(PO₄)₃ composite Na₃V₂(PO₄)₃/G] was obtained by using a solvothermal method and heat treatment, which can effectively improve the electronical conductivity of Na₃V₂(PO₄)₃. The as-obtained Na₃V₂(PO₄)₃/G composite in SIBs exhibited a stable specific capacity of 100.9 mA?h/g with a capacity retention of 68.4% after 230 cycles at 0.2 C in the voltage range of 0.01 - 3.00 V. Even at 5 C, its discharge capacity still reached to 65.2 mA?h/g. While the pure Na₃V₂(PO₄)₃ displayed a low specific capacity of 47.4 mA?h/g with an only 44.7% capacity retention at 0.2 C. At 5 C, it only delivered a discharge capacity of 25.1 mA?h/g. It proved that the graphene wrapped structure can significantly improve the cycling stability and rate performance of Na₃V₂(PO₄)₃.