Building stabilized Cu0.17Mn0.03V2O5−□·2.16H2O cathode enables an outstanding room-/low-temperature aqueous Zn-ion batteries

Abstract

Vanadium oxide cathode materials with stable crystal structure and fast Zn²⁺ storage capabilities are extremely important to achieving outstanding electrochemical performance in aqueous zinc-ion batteries. In this work, a one-step hydrothermal method was used to manipulate the bimetallic ion intercalation into the interlayer of vanadium oxide. The pre-intercalated Cu ions act as pillars to pin the vanadium oxide (V-O) layers, establishing stabilized two-dimensional channels for fast Zn²⁺ diffusion. The occupation of Mn ions between V-O interlayer further expands the layer spacing and increases the concentration of oxygen defects (O_d), which boosts the Zn²⁺ diffusion kinetics. As a result, as-prepared Cu_0.17Mn_0.03V₂O_5−□·2.16H₂O cathode shows outstanding Zn-storage capabilities under room- and low-temperature environments (e.g., 440.3 mAh g⁻¹ at room temperature and 294.3 mAh g⁻¹ at −60°C). Importantly, it shows a long cycling life and high capacity retention of 93.4% over 2500 cycles at 2 A g⁻¹ at −60°C. Furthermore, the reversible intercalation chemistry mechanisms during discharging/charging processes were revealed via operando X-ray powder diffraction and ex situ Raman characterizations. The strategy of a couple of 3d transition metal doping provides a solution for the development of superior room-/low-temperature vanadium-based cathode materials.