Microspherical copper tetrathiovanadate with stable binding site as ultra-rate and extended longevity anode for sodium-ion half/full batteries

Vanadium sulfides are appeared and investigated for the application of sodium-ion batteries (SIBs) due to their adjustable structure and high theoretical capacity. Nevertheless, their inferior sodiation/desodiation kinetics during cycling and convoluted Na⁺ storage mechanism severely restricts their application in SIBs. Herein, a facile one-step hydrothermal approach is applied to synthesize interconnected and homogeneous Cu₃VS₄ microspheres with enhanced intrinsic conductivity, which is beneficial for improving electrochemical kinetics and modulation the stress relief. As applied in SIBs, the Cu₃VS₄ delivers a high capacity of 500 mAh g⁻¹ after 100 cycles at 0.2 A g⁻¹. Impressively, an ultra-stable capacity of 274 mAh g⁻¹ after 25,000 cycles of Cu₃VS₄ can be achieved at 20 A g⁻¹. The first-principles calculations are detailed given to confirm the sodium storage mechanism and extended longevity of the Cu₃VS₄. A Na₃V₂(PO₄)₂O₂F cathode is constructed to assemble the full cell, also exhibiting a magnificent energy density of 171 Wh kg⁻¹ and remarkable cycling stability (5000 cycles). We first time show the comprehensive understanding of superior SIBs performance of Cu₃VS₄ from both experimental and theoretical perspectives, giving the possibility for the next-generation advanced energy storage device.