VO2(B)@carbon fiber sheet as a binder-free flexible cathode for aqueous Zn-ion batteries

Abstract

With the increase in the demand for future deformable and wearable devices, flexible aqueous zinc-ion batteries are deemed to show promise as a flexible electronic power supply. In this study, a type of a binder-less cathode material with a mass loading of 4.5 mg cm⁻² is successfully synthesized by a one-pot solvothermal method. By using a VO₂(B)@CFS (carbon fiber sheet) nanoflake array as the cathode material in zinc-ion batteries, the specific discharge capacity of the VO₂(B)@CFS nanoparticle array reaches up to 386.2 mA h g⁻¹ at 0.2 A g⁻¹, with an 88.6% capacity retention after 100 cycles; the excellent electrochemical performance is mainly attributed to the rapid ion or electron transfer rendered by the CFS-supported nano-chip array structure. Moreover, the electrochemical performance of VO₂(B)@CFS using the cost-effective ZnSO₄ electrolyte is compared with that using the Zn(CF₃SO₃)₂ electrolyte. In addition, two assembled 3 cm × 1 cm Zn/VO₂(B)@CFS flexible batteries connected in series can power a small light-emitting diode (LED) for up to 150 h without going out, providing a suitable design for a flexible cathode in aqueous zinc-ion batteries. This excellent cathode material is an ideal material for high-power flexible water-borne zinc-ion batteries.