Porous Na₃V₂(PO₄)₃ prepared by freeze-drying method as high performance cathode for sodium-ion batteries

Na₃V₂(PO₄)₃ has aroused extensive attention as next generation cathode material for sodium-ion batteries because of its abundance, good thermal stability and special 3D Na⁺ channel. In the current work, porous Na₃V₂(PO₄)₃ material is prepared by a simple freeze drying method followed by calcinations. Inside the porous material, Na₃V₂(PO₄)₃ particles are embedded in carbon matrix, thus forming facial electron channels and reducing Na⁺ ion diffusion distance at the same time. Benefiting from the special porous structure, this material displays excellent rate capability of 92.8 mA h g ⁻¹ at high rate of 20 C. Equally impressive is the long cycling stability. 90.2% of the initial capacity is retained after 2000 cycles at 5 C. This kind of feasible preparation method and beneficial design provide a good strategy for other materials to improve electric conductivity and cycling stability.