Na ₃ V ₂ (PO ₄ ) ₃ Anchoring on Carbon Spheres with Promoted Electrical Conductivity and Electrochemical Performance in Zn-Ion Storage

NASICON-type Na 3 V 2 (PO 4 ) 3 (NVP) is considered a promising cathode material for aqueous zinc-ion batteries due to its high operating voltage and substantial specific capacity. However, its practical application is significantly limited by poor electronic conductivity. To solve this problem, this paper introduces a carbon sphere framework supporting carbon-coated NVP (denoted as NVP-C@CSs). This composite was synthesized via a combination of hydrothermal and high-temperature calcination methods, which simultaneously improve conductivity and zinc storage capacity. The results indicate that the crystal structure of NVP remains intact after the introduction of CSs. Benefiting from the conductive CS framework, the NVP-C@CSs composite exhibits enhanced electronic conductivity (1.60 × 10 −4 vs 1.20 × 10 −4 S cm −1 ) and consequently superior electrochemical performance. At a low current density of 100 mA g −1 , the NVP-C@CSs composite delivers a discharge specific capacity of 126 mAh g −1 , higher than that of the NVP-C material (113 mAh g −1 ). The composite also exhibits excellent rate capability, with a capacity of 90 mAh g −1 at 2000 mA g −1 , significantly exceeding that of NVP-C (59 mAh g −1 ). This work provides an efficient approach to developing high-performance NVP composites for zinc-ion batteries.