Flexible transparent supercapacitor with core-shell Cu@Ni@NiCoS nanofibers network electrode

Abstract Transparent flexible supercapacitors are crucial for the progress of high-tech modern transparent wearable electronic gadgets. Thus, fabricating high opto-electrochemical performance electrodes is crucial for the development of high energy density transparent flexible supercapacitors. Herein, direct growth of battery-type ternary nickel-cobalt sulfide (NiCoS) nanosheets on Cu@Ni NFs network transparent electrode forming a seamless Cu@Ni@NiCoS NFs core-shell electrode structured is reported to boost the energy density of transparent supercapacitors. The core Cu@Ni nanofibers network electrode exhibited both excellent electro-optical performance (sheet resistance ~12.19 Ω/sq at ~89% transmittance) and high mechanical flexibility. NiCoS thin nanosheets shell offer high porosity, abundant active sites, and large electrode-electrolyte contact area, thus facilitating the fast diffusion of electrolytes into active materials. The Cu@Ni@NiCoS NFs core-shell electrode demonstrated remarkable high opto-electrochemical performance (transparency of ~76.83%, an areal capacity of 6.94 μA h/cm2, and high rate capability) and excellent mechanical properties. Finally, a transparent flexible symmetric supercapacitor device (SSC device) assembled by employing Cu@Ni@NiCoS NFs as both electrodes demonstrates an outstanding energy density of 0.48 μW h/cm2 at a power density of 11.15 μW/cm2 with device transparency of ~65%.