Unlocking the performance of sodium-ion batteries by coating Na3V2(PO4)3 with Nb2O5

Na 3 V 2 (PO 4 ) 3 (NVP) is a promising cathode material for sodium-ion batteries owing to its NASICON-type framework, which enables efficient reversible sodium insertion. However, its practical performance is limited by slow charge transfer at high cycling rates and cycling instability. Here, we report a facile impregnation method to deposit Nb 2 O 5 on NVP particles, aiming to enhance high-rate capability and long-term cycling stability. Structural and spectroscopic analyses (XRD, electron microscopy, Raman, XPS, and X-ray fluorescence spectroscopy) confirm the crystallinity of NVP and the uniform presence of Nb 2 O 5 on particle surfaces without compromising sodium reversibility. Electrochemical measurements reveal that Nb 2 O 5 -coated samples show the highest diffusion coefficients, ensuring superior high-rate performance and cycling stability. The 3% Nb 2 O 5 coating delivers the highest diffusion coefficients, superior cycling stability, and sustained capacity retention at a 1C rate. Cyclic voltammetry and impedance spectroscopy indicate enhanced surface capacitance, facilitating rapid sodium storage. XPS shows the conversion of Nb 2 O 5 into NbF 5 , resulting from HF scavenging, which improved interfacial stability. Extended cycling tests validate the long-term durability of the coated electrode. These results demonstrate that Nb 2 O 5 surface modification is an effective strategy to overcome the intrinsic limitations of NVP, offering a viable route to high-performance sodium-ion batteries. This study demonstrates that Nb 2 O 5 surface modification significantly enhances Na 3 V 2 (PO 4 ) 3 cathodes by improving charge transfer, diffusion, and interfacial stability, thereby enabling superior high-rate performance and long-term cycling durability in sodium-ion batteries.