Layered Structure Modification of Sodium Vanadate through Ca/F Co‐Doping for Enhanced Energy Storage Performance

Abstract Vanadate materials are promising for sodium‐ion batteries (SIBs) due to their low cost, high capacity, and high power characteristics enabled by vanadium's multiple oxidation states. However, their development is hindered by poor conductivity, suboptimal high‐rate performance, and limited cycle life. In this work, a layered structure modification strategy involving Ca/F co‐doping in sodium vanadate Na 2 CaV 2 O 6 F (CVF) is proposed to address these issues. Through a combination of experiments and density functional theory calculations, it is demonstrated that Ca/F synergies enhance the Na layer spacing in CVF, resulting in reduced crystal water content and volume shrinkage compared to Na 2 V 2 O 6 (NVO). Additionally, Ca/F incorporation significantly mitigates the diffusion potential of Na + within the material framework. The unmodified CVF sample exhibits a high reversible capacity of 220 mAh g −1 at 10 mA g −1 and an excellent rate capacity of 65.78 mAh g −1 at 400 mA g −1 . Furthermore, the cathode material maintains a capacity of up to 138 mAh g −1 at 200 mA g −1 and retains 104.88 mAh g −1 after 100 cycles within the voltage range of 1.5−4.0 V. These findings enhance the understanding of the crystal structure of NVO cathode materials and pave the way for the rational design of high‐quality vanadate cathodes for SIBs.