Manipulating Hierarchical Orientation of Wet-Spun Hybrid Fibers via Rheological Engineering for Zn-Ion Fiber Batteries.

Abstract

Wet-spinning is a promising strategy to fabricate fiber electrodes for real commercial fiber battery applications, according to its great compatibility with large-scale fiber production. However, engineering the rheological properties of the electrochemical active materials to accommodate the viscoelasticity or liquid crystalline requirements for continuous wet-spinning remains a daunting challenge. Here, with entropy-driven volume-exclusion effects, the rheological behavior of vanadium pentoxide (V₂ O₅ ) nanowire dispersions is regulated through introducing 2D graphene oxide (GO) flakes in an optimal ratio. By optimizing the viscoelasticity and liquid-crystalline behavior of the spinning dope, the wet-spun hybrid fibers display controlled hierarchical orientation. The wet-spun V₂ O₅ /rGO hybrid fiber with the optimal 10:1 mass fraction (V₂ O₅ /rGO_10:1 ) exhibits a highly oriented nanoblock arrangement, enabling efficient Zn-ion migration and an excellent Zn-ion storage capacity of 486.03 mAh g^-1 at 0.1 A g^-1 . A half-meter long quasi-solid-state fiber Zn-ion battery is assembled with a polyacrylamide gel electrolyte and biocompatible Ecoflex encapsulation. The thus-derived fiber Zn-ion battery is integrated into a wearable self-powered system, incorporating a highly efficient GaAs solar cell, which delivers a record-high overall efficiency (9.80%) for flexible solar charging systems.