Oxygen vacancies modulated copper oxide on carbon fiber for 3 V high-energy-density supercapacitor in water-soluble redox electrolyte

Although water-soluble redox based supercapacitors (SCs) had attractive supercapacitor characteristics, they still suffered from problems of low operating voltages and unsatisfactory energy density. Herein, it was reported that the oxygen defect modulated copper oxide on flexible carbon fiber (denoted as CuOx/CF) achieved a broad potential range of up to 3.0 V in 1 M Na2SO4 contained 0.05 M K4[Fe (CN)(6)]/K-3[Fe (CN)(6)] electrolyte. Oxygen defects in CuOx/CF improved charge transfer efficiency, adjust [Fe (CN)(6)](3-/4-)ions diffusion and stimulated more pseudocapacitive behavior, which demonstrated by electrochemical characterization and theoretical calculation results. It is noteworthy that the 3.0 V high voltage water-soluble CuOx/CF based symmetric supercapacitor yielded a maximum energy density of 53.1 Wh kg(- 1) at a power density of 1950 W kg(- 1) and exceptionally remarkable cycling durability of 98.9%. This work presented a viable strategy for constructing wide-voltage flexible supercapacitor devices.

Automated summary

In this study, a water-soluble double-layer supercapacitor using CuOx/CF as the electrode material was reported, which showed excellent supercapacitor performance within a wide potential range of up to 3.0 V and remarkable cycling stability.