Tuning the electronic structure of layered vanadium pentoxide by pre-intercalation of potassium ions for superior room/low-temperature aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (ZIBs), due to their sluggish Zn²⁺ diffusion kinetics, continue to face challenges in terms of achieving superior high rate, long-term cycling and low-temperature properties. Herein, K⁺ pre-intercalated layered V₂O₅ (K_0.5V₂O₅) composites with metallic features are capable of delivering excellent zinc storage performance. Specifically, the K_0.5V₂O₅ electrode delivers a high reversible capacity of 251 mA h g⁻¹ at 5 A g⁻¹ after 1000 cycles. Even at a low temperature of −20 °C, high reversible capacities of 241 and 115 mA h g⁻¹ can be obtained after 1000 cycles at 1 and 5 A g⁻¹, respectively. The outstanding electrochemical performance is attributed to the incorporation of K⁺ into the layered V₂O₅, which acts as pillars to promote the Zn²⁺ diffusion and increase the structural stability during cycling. Density functional theory calculations demonstrate that the interlayer doping of K⁺ can benefit electron migration, and therefore enhance the Zn²⁺ (de)intercalation kinetics. Meanwhile, the Zn²⁺ storage mechanism of K_0.5V₂O₅ is revealed by ex situ X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy characterization. This work may pave the way for exploiting high-performance cathodes for aqueous ZIBs.