Fiber-Shape Na3V2(PO4)2F3@N-Doped Carbon as a Cathode Material with Enhanced Cycling Stability for Na-Ion Batteries.

To overcome intrinsic low electronic conductance, delicately designed fiber-shape Na3V2(PO4)2F3@N-doped carbon composites (NVPF@C) have been prepared for boosting Na-storage performance. This distinctive interlinked three-dimensional network structure can effectively facilitate electron/Na-ion transportation by decreasing the NVPF particle size to shorten the ionic diffusion paths and introducing a conducting N-doping carbon scaffold to improve electronic conductivity. Benefiting from the favorable structural design and fascinating reaction kinetics, the modified NVPF@C material demonstrates superior sodium-storage performance with 109.5 mAh g-1 high reversible capacity at a moderate current of 0.1 C, excellent rate tolerance of 78.9 mAh g-1 at a high rate of 30 C, and gratifying long-term cyclability (87.8% capacity retention after 1000 cycles at 20 C; 83.4% capacity retention after 1500 round trips at a ultrahigh rate of 50 C). The fascinating electrochemical performance remains stable when NVPF@C was examined as the cathode material for a full cell, suggesting the fiber-shape NVPF@C as one of the most promising applicable materials for sodium-ion batteries. Moreover, the approach of the three-dimensional conductive network by electrospinning is proposed as a strategy of efficiency and promising prospect to enhance the electrochemical property of other materials for sodium-ion batteries.