Intercalation Pseudocapacitive Zn2+ Storage with Hydrated Vanadium Dioxide toward Ultrahigh Rate Performance

The weak van der Waals interactions enable ion‐intercalation‐type hosts to be ideal pseudocapacitive materials for energy storage. Here, a methodology for the preparation of hydrated vanadium dioxide nanoribbon (HVO) with moderate transport pathways is proposed. Out of the ordinary, the intercalation pseudocapacitive reaction mechanism is discovered for HVO, which powers high‐rate capacitive charge storage compared with the battery‐type intercalation reaction. The main factor is that the defective crystalline structure provides suitable ambient spacing for rapidly accommodating and transporting cations. As a result, the HVO delivers a fast Zn2+ ion diffusion coefficient and a low Zn2+ diffusion barrier. The electrochemical results with intercalation pseudocapacitance demonstrate a high reversible capacity of 396 mAh g−1 at 0.05 A g−1, and even maintain 88 mAh g−1 at a high current density of 50 A g−1. A structural design method is presented wherein lattice defects and crystal water are introduced into vanadium dioxide. The high‐rate electrochemical behavior stems from intercalation pseudocapacitance, promoting the surface‐controlled capacitance feature. The suitable crystal structure makes the solid ion‐diffusion process no longer the rate‐limiting step.