V2O5 nanosheets supported on 3D N-doped carbon nanowall arrays as an advanced cathode for high energy and high power fiber-shaped zinc-ion batteries
Increasing efforts have been devoted to developing high-performance flexible Zn-ion batteries for wearable electronics due to acceptable security, high eco-efficiency, and abundant resources. Nevertheless, the practical applications of Zn-ion batteries are still limited by their relative low energy and power density as well as poor rate capability. Herein, we constructed a finely crafted nanocomposite with a hierarchical core–shell structure on a carbon nanotube fiber (CNTF), in which three-dimensional high-conductivity porous N-doped carbon nanowall arrays and two-dimensional thin V2O5 nanosheets serve as the core and shell (NC@V2O5), respectively. The unique construction not only greatly increases the mass loading of active materials, but also enhances the electron transfer and ion diffusion of the electrode. Benefitting from these synergistic effects, an assembled all-solid-state fiber-shaped Zn-ion battery using CNTF@NC@V2O5 as a binder-free cathode delivers an ultrahigh volumetric capacity of 457.5 mA h cm−3 at a current density of 0.3 A cm−3 and maintains 47.5% of the initial capacity when the current density increases to 30.0 A cm−3, indicating an excellent rate capability. Furthermore, the battery simultaneously achieves both a high energy density of 40.8 mW h cm−3 and a power density of 5.6 W cm−3, outperforming most previously reported quasi/all-solid-state energy storage devices. Thus, our work paves a novel way to construct high-performance fiber-shaped energy storage devices for next-generation wearable electronics.