Boosting the performance of sodium vanadate as cathode of flexible zinc-ion batteries by incorporating MXenes

Herein, we propose an innovative flexible cathode design for zinc-ion batteries (ZIBs) through the strategic integration of sodium vanadate (NaV₃O₈·1.5H₂O) with two-dimensional MXene nanosheets (Ti₃C₂ or Mo₂C). The composite architecture leverages MXene’s dual advantages of exceptional electrical conductivity and surface hydrophilicity to significantly enhance the electrochemical performance of the vanadate host. The NaV₃O₈·1.5H₂O was synthesized through a reaction between V₂O₅ and NaCl aqueous solution, followed by hybridization with MXene in NaCl solution. When configured into full cells with zinc foil anode and 3 M Zn(CF₃SO₃)₂ electrolyte, the optimized composite with 11 wt.% Ti₃C₂ MXene demonstrates remarkable electrochemical enhancement, delivering a specific capacity of 339.6 mAh/g at 1 A/g, a 30.86% improvement over pristine NaV₃O₈·1.5H₂O (259.5 mAh/g). The MXene-modified cathode exhibits extraordinary cycling stability with near 100% capacity retention after 3800 cycles at 3 A/g, outperforming the pure vanadate counterpart that degrades to 103.6 mAh/g after only 2000 cycles. A capacity improvement, the incorporation of MXene also increases the structural stability of the cathode during flexible test cycles. It maintains a capacity of 227.9 mAh/g at 1 A/g under extreme 90° bending/twisting deformations. This synergistic combination of high energy density (381.5 mAh/g at 0.1 A/g), ultralong cycle life, and mechanical endurance positions the MXene-vanadate composite as a promising candidate for next-generation flexible energy storage systems.