Rational design of two dimensional single crystalline Na3V2(PO4)2F3 nanosheets for boosting Na+ migration and mitigating grain pulverization

Sodium-ion batteries (SIBs) have received considerable attention as stationary energy storage applications. However, it is still a challenge to develop high energy density and stable cathode materials for SIBs. Na3V2(PO4)(2)F-3, as one of the most promising polyanion-type cathodes, has been explored due to its high reversible capacity and high discharge voltage. In spite of excellent intrinsic features, poor rate capability ascribed to the intrinsically low electronic conductivity and unsatisfactory ion conductivity, as well as grain pulverization, severely hinders their practical applications. Based on density functional theory calculations and common knowledge about two dimensional materials, it is believed that rational design of two dimensional single crystalline Na3V2(PO4)(2)F-3 nanosheets could be an effective route to enhance Na+ migration and mitigate grain pulverization for high-performance SIBs. Besides, combing Na3V2(PO4)(2)F-3 and three-dimensional porous carbon, a composite of two dimensional Na3V2(PO4)(2)F-3 wrapped with three dimensional porous carbon, was synthesized and utilized as cathode for SIBs. When evaluated as cathode, NVPF@3Dc exhibits a high specific capacity of 131.5 mAh g 1 at 0.2 C, excellent rate property of 65.7 mAh g(-1) at 10 C, and long lifespan of 2500 cycles with the capacity of 51.6 mAh g 1 at 5 C.