石墨烯包封Na_(3)V_(2)(PO_(4))_(3)用作钠离子电池负极材料的电化学性能探究

Electrochemical Performance Investigation of Graphene Wrapped Na_(3)V_(2)(PO_(4))_(3) as Anode Material for Sodium Ion Battery

具有三维网络结构的NASICON型Na_(3)V_(2)(PO_(4))_(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Na_(3)V_(2)(PO_(4))_(3)的复合材料[Na_(3)V_(2)(PO_(4))_(3)/G],有效提高了Na_(3)V_(2)(PO_(4))_(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,Na_(3)V_(2)(PO_(4))_(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Na_(3)V_(2)(PO_(4))_(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Na_(3)V_(2)(PO_(4))_(3)的循环稳定性和倍率性能。

NASICON-type Na_(3)V_(2)(PO_(4))_(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 Na_(3)V_(2)(PO_(4))_(3) composite[Na_(3)V_(2)(PO_(4))_(3)/G]was obtained by using a solvothermal method and heat treatment,which can effectively improve the electronical conductivity of Na_(3)V_(2)(PO_(4))_(3).The as-obtained Na_(3)V_(2)(PO_(4))_(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 Na_(3)V_(2)(PO_(4))_(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 Na_(3)V_(2)(PO_(4))_(3).