Block-assembled Na₃V₂O₂(PO₄)₂F@rGO microspheres as high-rate and ultra-long-life cathode materials for sodium-ion batteries

Excellent cathode materials are the key technology to improve the cycle life and stability of sodium-ion batteries. Vanadium-based polyanionic compounds have attracted extensive research interest as promising cathode materials due to their high energy density, good electrochemical properties and structural stability. Herein, block-assembled Na₃V₂O₂(PO₄)₂F@rGO microspheres were synthesized via a hydrothermal method, and the Na₃V₂O₂(PO₄)₂F@7.3 wt% rGO microspheres achieved the best electrochemical performance among samples with different proportions of rGO, exhibiting a specific capacity of 123.6 mAh g⁻¹ at 1C and remarkable cycle stability under high current density with 76.7% capacity retention after 1000 cycles at 10C. Their high performance can be attributed to their unique rGO-wrapped spherical morphology, which provides continuous channels and a stable structure for electron transfer and sodium ion intercalation or extraction.