Dopamine-intercalated vanadate hollow microtube arrays with S-doping for high-performance zinc-ion batteries: disorder/defect-induced clusters and a reversible phase transition

Abstract

S-undoped or -doped (C₈H₉NO₂)_0.18V₂O₅ (DA-VO) was synthesized by a facile one-step hydrothermal reaction of dopamine (DA) and V₂O₅ or VS₂. Rietveld refinement reveals the intercalation of DA into V₂O₅ with a large interlayer spacing of 11.0 Å. The S-doped sample DA-VO (S) was obtained based on the transformation of VS₂ → V₂O₅ and the doping of the in situ released S element. DA-VO (S) exhibits a unique morphology of hollow microtube arrays built by cross-linked nanoribbons and provides a high specific capacity (476 mA h g⁻¹ at 0.1 A g⁻¹) and excellent long-term cycling durability with capacity retention of ∼95.3% over 3000 cycles at 5 A g⁻¹ and ∼77.7% over 1000 cycles at 1 A g⁻¹. It is associated with the intercalated DA, which not only increases the interlayer spacing of vanadium oxide, but also offers extra capacity due to the phenol–keto conversion. Furthermore, the disorders/defects and polyoxovanadate clusters induced by S-doping lead to a pseudo-reversible partial phase transition of DA-VO (S) ↔ Zn-doped H_xV₂O₅. However, the undoped counterpart only experiences a transformation of DA-VO → Zn₃(OH)₂V₂O₇·2H₂O due to the irreversible capture of Zn²⁺, as evidenced by density functional theory (DFT) calculations.