Ultrafast Synthesis of Large-Sized and Conductive Na₃V₂(PO₄)₂F₃ Simultaneously Approaches High Tap Density, Rate and Cycling Capability

The Na3V2(PO4)(2)F-3 (NVPF) cathode material is usually nano-sized particles exhibiting low tap density, high specific surface area, correspondingly low volume energy density, and cycle stability of the sodium-ion batteries (SIBs). Herein, a high-temperature shock (HTS) strategy is proposed to synthesize NVPF (HTS-NVPF) with uniform conducting network and high tap density. During a typical HTS process (heating rate of 1100 degrees C s(-1) for 10 s), the precursors rapidly crystallize and form large-sized and dense particles. The tight connection between particles not only enhances their contact with carbon layers, but also reduces the specific surface area that inhibits side reactions between the interfaces and the electrolyte. Besides, ultrafast synthesis of NVPF reduces the F loss and amount of Na3V2(PO4)(3) impurities, which improve cycling capability. The HTS-NVPF demonstrates a high energy density of 413.4 Wh kg(-1) and an ultra-high specific capacity of 103.4 mAh g(-1) at 10 C as well as 84.2% capacity retention after 1000 cycles. In addition, the excellent temperature adaptability of HTS-NVPF (-45-55 degrees C) and remarkable electrochemical properties of NVPF||HC full cell demonstrate extreme competitiveness in commercial SIBs. Therefore, the HTS technique is considered to be a high-efficiency strategy to synthetize NVPF and is expected to prepare other cathode materials.