Carbon-Coated Na₃V₂(PO₄)₃ Anchored on Freestanding Graphite Foam for High-Performance Sodium-Ion Cathodes

Na₃V₂(PO₄)₃ (NVP) has been considered as a most promising cathode material for sodium-ion batteries (SIBs), but NVP usually exhibits poor cycling stability and rate performance due to the low intrinsic electrical conductivity. Herein, we prepared carbon-coated Na₃V₂(PO₄)₃ anchored on freestanding graphite foam (denoted as NVP@C-GF) as a cathode for SIBs. The NVP@C-GF exhibits superior sodium-ion storage performance, including rate capability (56 mAh g^-1 at 200 C) and long cycle life (54 mAh g^-1 at 100 C after 20 000 cycles). The resulting NVP@C-GF inherits the advantages of 3D free-standing graphite that possesses high electrical conductivity and porous structure for the electrolyte to soak in. Furthermore, carbon-coated NVP particles anchored on the surface of GF not only accommodate the volume change of NVP during charge/discharge but also reduce the diffusion distance of the Na⁺ ion.