Ultrahigh rate binder-free Na3V2(PO4)3/carbon cathode for sodium-ion battery

Sodium ion batteries (SIBs) are very promising for large-scale energy storage in virtue of its high energy density, abundant sodium resources and low environmental impact, etc. However, it is still a big challenge to develop high-performance and durable cathode materials for SIBs. Among different candidate materials, Na3V2(PO4)(3) has attracted great attentions due to its high theoretical capacity (117 mAh/g), stable framework structure and excellent ionic conductivity. However, Na3V2(PO4)(3) delivers inferior rate capability and cycling stability due to its poor electronic conductivity. In this work, free-standing Na3V2(PO4)(3)/carbon nanofiber membranes are synthesized by an electrospinning-sintering route. The sample could deliver excellent cycling capability with specific capacity of 112 mAh/g at 1 C after 250 cycles and ultrahigh rate capability with 76.9 mAh/g even at 100 C, which is superior to many state-of the-art SIB cathode materials. This can be attributed to the hierarchically distributed Na3V2(PO4)(3) crystals in carbon nanofiber network, which possesses outstanding electronic/ionic conductivity and thus leads to an ultrahigh rate capability. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.