In situ grown 2D hydrated ammonium vanadate nanosheets on carbon cloth as a free-standing cathode for high-performance rechargeable Zn-ion batteries

Abstract

Due to their low cost and high safety, aqueous rechargeable Zn-ion batteries (ARZIBs) have attracted considerable attention for large-scale energy storage systems but the limited capacity and energy density hinder their wide application due to the lack of advanced cathode materials. Recently, ammonium vanadates have received huge interest as cathode materials for ARZIBs. However, all previously reported works have been usually focused on electrodes comprising ammonium vanadates, a conductive agent, and a binder. Herein, we report 2D hydrated ammonium vanadate nanosheets (NV NSs) grown on alkali-treated carbon cloth (denoted as NV NSs@ACC) as the free-standing cathode for high performance ARZIBs. This as-prepared cathode enables fast ion/electronic transport and reduces the aggregation of ultrathin NV NSs. The NV NSs@ACC cathode in coin-type batteries can deliver a high reversible capacity of 523 mA h g⁻¹ at a current density of 0.1 A g⁻¹ and a remarkable energy density of 343 W h kg⁻¹ at 150 W kg⁻¹ based on the mass weight of NV NSs. Furthermore, the quasi-solid-state flexible battery assembled with NV NSs@ACC as the cathode and Zn NSs@CC as the anode shows an outstanding cycling stability (93.4% capacity retention after 1000 cycles at 1 A g⁻¹) with high coulombic efficiency. This work is expected to promote V-based nanomaterials on CC for the development of ARZIBs for large-scale applications and even for use in flexible energy storage devices.