All-pseudocapacitive coordination towards flexible asymmetric fiber-shaped supercapacitors with ultrahigh energy and power density

Abstract

Fiber-shaped supercapacitors (FSSCs) with high rate-capability, light weight, and knittability are promising members of future flexible energy storage clubs. However, limited by the trade-off between capacity density and transport kinetics of fiber electrodes, the FSSC often delivers an insufficient energy density and power density, suppressing its practical application prospects. Here, an aqueous asymmetric FSSC is developed, which is composed of highly conductive positive and negative electrodes with coordinated pseudocapacitive characteristics, achieving a balance of electrochemical performances. Benefiting from the wide voltage window and quick ion transport kinetics in the gel electrolyte, this asymmetric fiber device gives an ultrahigh energy density of 41 mW h cm⁻³ and a high power density of 725 mW cm⁻³, outperforming most state-of-the-art aqueous asymmetric or symmetric FSSCs. Moreover, it can power commercial electronic devices with excellent flexibility and bendability, demonstrating a promising avenue for fiber-based energy storage devices with great practical importance.