Designing vanadium-based nanoflower precursor towards improved Na3V2(PO4)3 cathode of sodium-ion batteries

The sodium superionic conductor Na3V2(PO4)3 (NVP) is a promising cathode material for sodium-ion batteries due to its high energy density and efficient ion diffusion pathways. Nonetheless, the conventional solid-state reaction synthesis of NVP suffers from limitations such as a small surface area, irregular shape, and suboptimal electrochemical properties. To address these challenges, a two-step approach is masterfully designed in this study, commencing with the modulation of the morphology of vanadium-based precursor through chemical precipitation. Subsequently, the uniform carbon-coated porous NVP@C composite with a significantly enhanced specific surface area of 83.22 m2 g-1 is devised through the solid-state reaction. Compared to traditional precipitation methods producing VO(OH)2 from VOSO4 solution, which have low efficiency and uneven precursor formation, adding cetyltrimethylammonium bromide (CTAB) as a surfactant enhanced vanadium precipitation (99.9%) and yielded uniform nanoflower-shaped precursor with a large surface area. Remarkably, the synthesized NVP@C composite achieved an impressive reversible capacity of 87.7 mA h g-1 at a challenging 5 C rate, with 80.0% capacity retention after 1000 cycles. These findings highlight the ability to control precursor morphology and enhance surface area contributes significantly to the favorable properties and electrochemical performance of the resulting materials, promoting their viability for advanced energy storage applications.