Polymer-ligand functionalized MXene and hollow silica composite anode for improved sodium-ion batteries

Two-dimensional MXenes combine metallic conductivity and tunable surface chemistry, making them attractive for energy storage. Their application, however, is constrained by rapid oxidation and restacking. Here we report surface functionalization of MXene using polyvinylpyrrolidone-catechol at room temperature to support higher oxidation stability and stable dispersion at ambient conditions. When coupled with hollow silica (HS) to form a composite anode for sodium-ion batteries, the HS buffers the passivation due to sodiation while the functionalized-MXene network ensures efficient electron/ion transport. The functionalized-MXene/HS anode achieves ~841 mAh g-1 at 0.1 A g-1 and ~491 mAh g-1 at 0.5 A g-1, outperforming bare HS (444 and 191 mAh g-1), along with ~95% enhancement in ionic conductivity. The full cell studies against Prussian blue analogue cathode proved the high reversible capacity. This scalable surface chemistry approach stabilizes MXenes and unlocks their potential in high-performance sodium-ion batteries and beyond. Two-dimensional MXenes offer promising potential for energy storage but are limited by rapid oxidation and restacking issues. Here, the authors enhance MXene stability through polyvinylpyrrolidone-catechol functionalization, achieving superior performance in sodium-ion batteries with a composite anode, demonstrating significant improvements in capacity and ionic conductivity, and paving the way for advanced energy storage solutions.