Hydrangea-like BiVO4-V2C endogenous heterostructure for superior Na plus storage

Sodium ion batteries (SIBs) have garnered more and more attentions owing to the uneven distribution and increasing price of lithium mineral. Herein, BiVO4-V2C endogenous heterostructures as anode for SIBs are synthesized via one-step in situ hydrothermal method. The designed hydrangea-like heterostructure ensures a wide contact surface for the interaction of anode material with the electrolyte, and endows stable heterojunction interfaces between BiVO4 and V2C MXene, the synergistic effect of which significantly improves the electrical conductivity, pseudo-capacitance and alleviates the volumetric change of BiVO4 during charge/discharge process. Density functional theory (DFT) calculations ulteriorly demonstrate that the electric field at the BiVO4-V2C interface contributes to the excellent Na ion diffusion kinetics and impressive sodium storage capacity. As a result, the BiVO4-V2C anode achieved outstanding performance with a high discharge capacity (480 mAh g-1 after 600 cycles at 0.2 A g-1), and impressive long-term lifespan (303 mAh g-1 over 2000 cycles at 1 A g- 1). This work reveals a new design of novel V2C MXene heterojunctions which coupling with BiVO4 combined with the analysis of amorphous/crystalline interface, developing a proper strategy for the effective energy storage of sodium.