Vanadium Pentoxide Nanofibers/Carbon Nanotubes Hybrid Film for High-Performance Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) with the characteristics of low production costs and good safety have been regarded as ideal candidates for large-scale energy storage applications. However, the nonconductive and non-redox active polymer used as the binder in the traditional preparation of electrodes hinders the exposure of active sites and limits the diffusion of ions, compromising the energy density of the electrode in ZIBs. Herein, we fabricated vanadium pentoxide nanofibers/carbon nanotubes (VO/CNTs) hybrid films as binder-free cathodes for ZIBs. High ionic conductivity and electronic conductivity were enabled in the VO/CNTs film due to the porous structure of the film and the introduction of carbon nanotubes with high electronic conductivity. As a result, the batteries based on the VO/CNTs film exhibited a higher capacity of 390 mAh g at 1 A g, as compared to batteries based on VO (263 mAh g). Even at 5 A g, the battery based on the VO/CNTs film maintained a capacity of 250 mAh g after 2000 cycles with a capacity retention of 94%. In addition, the VO/CNTs film electrode also showed a high energy/power density (e.g., 67 kW kg/267 Wh kg). The capacitance response and rapid diffusion coefficient of Zn (~10 cm s) can explain the excellent rate capability of VO/CNTs. The vanadium pentoxide nanofibers/carbon nanotubes hybrid film as binder-free cathodes showed a high capability and a stable cyclability, demonstrating that it is highly promising for large-scale energy storage applications.