Binder-free V₂O₅-carbon nanotube composite films for high-performance aqueous manganese-ion batteries

Aqueous manganese-ion batteries (MIBs) are considered a possible choice for energy storage systems as the Mn anode offers superior theoretical capacity and low redox potential. However, the capacities of the cathode materials are usually limited by the large radius of the solvated Mn²⁺. Herein, binder-free V₂O₅-carbon nanotube film (VO-CNT) cathodes were designed through a straightforward suction filtration method. In the films, V₂O₅ with an open layered framework provided abundant ion transfer channels, and more importantly, the VO-CNT cathodes allowed the co-intercalation/extraction of Mn²⁺ and H⁺ ions. This charge storage mechanism significantly optimized the electrochemical performance of the batteries. In addition, the carbon nanotubes formed a continuous high-conductive scaffold in the film, which contributed to the overall good conductivity of the cathode. Leveraging the synergistic advantages of V₂O₅ and carbon nanotubes, the binder-free VO-CNT cathodes displayed a high capacity, an exceptional rate capability, and robust cycling stability, retaining 96% capacity over 1000 cycles. This work provides a novel method in the design of high-performance cathodes for aqueous MIBs.