A high-capacity aqueous zinc-ion battery fiber with air-recharging capability

Abstract

Flexible fiber batteries with self-powering functionality will offer new opportunities for next-generation wearable electronic devices. Here, we present a high-capacity aqueous Zn-ion battery fiber that can directly harvest energy from ambient air to recharge without using additional power supply. The air-recharging capability stems from the freestanding cathode fiber consisting of nano-structured V₆O₁₃/aligned carbon nanotubes, which can induce a spontaneous redox reaction with ambient air at its discharged state for capacity recovery. This air-recharging process is reversible and compatible with the routine galvanostatic charge–discharge of aqueous Zn-ion batteries. The resultant battery fiber shows a high specific capacity (371 mA h g⁻¹ at 200 mA g⁻¹), stable cyclability (91% capacity retention after 5000 cycles at 5 A g⁻¹), and can be efficiently recharged to ∼60% upon exposure to air. Finally, we demonstrate a self-charging battery fiber to effectively power a strain sensor in an integrated, wearable fingertip.