A Composite Strategy on H2V3O8 and Carbon Fibers: Boosting the Mechanical and Electrochemical Performance of the Fiber Cathodes in Zinc‐Ion Fiber Batteries

Flexible fiber batteries can be integrated into irregular spaces, allowing conventional structures to store energy. Preserving electrochemical performance while improving mechanical strength can substantially broaden their application potential. Here, H2V3O8 and nickel‐plated carbon fibers are combined for the first time to construct a composite fiber cathode for zinc‐ion fiber batteries. A continuous wet spinning and pressing method is employed to fabricate the fiber cathode, leveraging the respective advantages of the core and active materials. The nickel‐plated carbon fibers, which exhibit high electrical conductivity, serve effectively as current collectors, and their favorable mechanical properties confer excellent flexibility and an ultimate tensile strength of 361.9 MPa to the fiber electrode. Owing to the deformability of carbon fibers and the pressing step, the electrode acquires a rectangular cross‐section, which contributes to improved electrochemical performance. When assembled with a zinc/carbon fibers composite anode and a hydrogel electrolyte into a battery, it delivers a specific capacity of 138 mAh g−1 at 3 A g−1 after 1500 cycles. This work demonstrates a balance between mechanical and electrochemical performance in fiber electrodes, supporting their potential for structural energy storage applications.