In situ crafting of a 3D N-doped carbon/defect-rich V 2 O 5- x · n H 2 O nanosheet composite for high performance fibrous flexible Zn-ion batteries.

Aqueous fibrous batteries with tiny volume, light weight and stretchability have furthered wearable smart textile systems like biocompatible electronics for a more efficient use of electricity. Challenges still faced by fibrous batteries include not only the deficient actual capacity but the cyclability on the cathode side. Herein, an in situ anodic oxidation strategy is reported to prepare 3D N-doped/defect-rich V 2 O 5- x · n H 2 O nanosheets (DVOH@NC) as fibrous cathodes for aqueous zinc-ion batteries (AZIBs). Benefiting from the substantially abundant reaction sites, enhanced electrical conductivity, short electron/ion diffusion path and high mass loading, the newly designed DVOH@NC fibrous electrode delivers impressive capacity (711.9 mA h cm -3 at 0.3 A cm -3 ) and long-term durability (95.5% capacity retention after 3000 cycles), substantially outperforming previously reported fibrous vanadium-based cathodes. First-principles density functional theory (DFT) calculations further revealed that the oxygen vacancies can weaken the electrostatic interaction between Zn 2+ and the host cathode accompanying the low Zn 2+ diffusion energy barrier. To highlight the potential applications, a prototype wearable fiber-shaped AZIB (FAZIB) with remarkable flexibility and extraordinary weaving capability was demonstrated. More encouragingly, the resulting FAZIB could be charged with solar cells and power a pressure sensor. Thus, our work provides a promising strategy to rationally construct high-performance flexible vanadium-based cathodes for next-generation wearable AZIBs.