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 HxV2O5. 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.