Design and Construction of 3D Porous Na3V2(PO4)3/C as High Performance Cathode for Sodium Ion Batteries

An easy and delicate approach using cheap carbon source as conductive materials to construct 3D sequential porous structural Na3V2(PO4)3/C(NVP/C) with high performance for cathode materials of sodium ion battery is highly desired. In this paper, the NVP/C with 3D sequential porous structure is constructed by a delicate approach named as “cooking porridge” including evaporation and calcination stages. Especially, during evaporation, the viscosity of NVP/C precursor is optimized by controlling the adding quantity of citric acid, thus leading to a 3D sequential porous structure with a high specific surface area. Furthermore, the NVP/C with a 3D sequential porous structure enables the electrolyte to interior easily, providing more active sites for redox reaction and shortening the diffusion path of electron and sodium ion. Therefore, benefited from its unique structure, as cathode material of sodium ion batteries, the 3D sequential porous structural NVP/C exhibits high specific capacities(115.7, 88.9 and 74.4 mA·h/g at current rates of 1, 20 and 50 C, respectively) and excellent cycling stability (107.5 and 80.4 mA·h/g are remained at a current density of 1 C after 500 cycles and at a current density of 20 C after 2200 cycles, respectively).