Boosting interfacial reaction kinetics in yarn-shaped zinc-V2O5·nH2O batteries through carbon nanotube intermediate layer integration

Flexible yarn-shaped batteries are promising candidates for the wearable electronics owing to their good flexibility, tiny volume, compatibility with textiles. However, their practical applications are hindered by low capacity, active material mass loading, and energy density. Herein, we develop a coaxially wrapping strategy to fabricate an advanced yarn-shaped aqueous zinc-ion batteries (AZIBs) incorporating core-sheath carbon nanotube (CNT)/V2O5·nH2O composite yarns as cathodes and zinc wire as anodes. The as-wrapped CNT intermediate layer not only enhances the surface's conductivity, but the nano-array porous layer can also accelerate the mixing of ion concentration between the electrode surface and the electrolyte fluid through the turbulence effect, thereby improving the interfacial ion/electron kinetics. As a result, the energy storage mechanism of CNT/V2O5·nH2O yarn AZIBs transformed from capacitive-dominant to diffusion-controlled process, and the batteries demonstrate exceptional discharge capacity of 566.7 mAh g−1 at 0.1 A g−1, surpassing the state-of-art yarn-based AZIBs and approaching the theoretical zinc storage capacity (589 mAh g−1). In addition, they exhibit a high energy density of 471 Wh kg−1 at 25.5 W kg−1 and excellent cycling performance. This work opens a new and efficient avenue for the structure design of high-performance electrode materials for flexible yarn-based batteries.