Hollow-Structured V₂C MXene Nanosheets/Carbon Nanocomposites for Aqueous Zinc Ion Batteries

Two-dimensional transition metal carbides and nitrides (MXenes) have garnered increasing attention in energy storage devices due to their competitive performance. However, the inherent characteristic of two-dimensional materials to restack and aggregate significantly limits the full exploitation of the properties of MXene. In this study, we first explore the etching conditions of V 2 C MXene via a sealed hydrothermal reaction, and successfully synthesize high-quality accordion-like V 2 C MXene. Subsequently, two-dimensional V 2 C MXene nanosheets of small size were attached to the surface of poly(methyl methacrylate) (PMMA) by self-assembly effect. Three-dimensional self-supporting hollow spherical nanocomposite structures (H–V 2 C/C) are obtained through a sacrificial template method. Benefiting from the extra reaction space inherent to the hollow structure, along with the stability and conductivity of the carbon material, H–V 2 C/C can provide abundant active sites, fast ion transport path, and stable physical structure as the cathode, thus significantly improving the electrochemical performance of aqueous zinc-ion batteries (ZIBs). Compared to nanosheet-like V 2 C MXene, the H–V 2 C/C cathode material broadens the voltage window of ZIBs from 0.2–1.1 V to 0.2–1.5 V, significantly improving energy density and effective capacity. At a current density of 0.1 A g –1, the H–V 2 C/C cathode exhibits an initial capacity of 517.3 mAh g –1, which further increases to an ultrahigh capacity of 659.8 mAh g –1 after 89 cycles. Even when the current density is increased to 5 A g –1, the material retains 75.3% of its capacity after 4000 cycles. This study significantly improves the potential of MXene-based material properties in ZIBs through structural design and material modification, providing an idea for the development of the next generation of high-performance energy storage systems.