Constructing 2D VO2 nanoplates embedded in a carbon matrix as high-performance cathode material for aqueous zinc ion batteries

Although VO2 possesses an attractive theoretical specific capacity and a shear-type structure to resist lattice shear during repeated Zn2+ insertion/extraction, its poor electrical conductivity, easy self-aggregation, and inferior stability lead to sluggish reaction kinetics and unsatisfactory Zn2+ storage performance. In this work, we successfully constructed novel 2D VO2 nanoplates embedded in a carbon matrix (VO2/carbon) utilizing a straightforward hydrothermal approach without using any template or calcination procedure. The thickness of the carbon layer can be tuned by modulating the experimental conditions. Impressively, the obtained 2D VO2/carbon with the optimal thickness of the carbon layer displayed satisfactory cyclic stability (63 % capacity maintained after 2500 cycles at 3 A g-1), excellent rate capability (202 mAh g-1 at 5 A g-1), and high specific capacity (501 mAh g-1 at 0.1 A g-1) as cathode material for aqueous zinc ion batteries (ZIBs), attributed to the desirable 2D nanoplate structure that offers effective pathways for Zn2+ diffusion together with sufficient electroactive sites for redox reactions and moderate carbon coating that buffers the volume changes in the course of repeated insertion/extraction of Zn2+ and accelerates charge/ion transfer. Furthermore, two assembled Zn//VO2/carbon coin cells successfully lit an orange light-emitting diode (LED) light for over 5 h, highlighting their potential as ideal candidates for low-cost, high-performance, environmentally friendly, and intrinsically safe energy storage devices.