Thorn-like nanostructured NiCo2S4 arrays anchoring graphite paper as self-supported electrodes for ultrahigh rate flexible supercapacitors.

Vertically stacked thorn-like nanostructured NiCo 2 S 4 arrays are designed to in-situ grow on the electrochemical oxidized graphite paper by a two-step hydrothermal method where graphite papers act as heterogeneous nuclear sites to rationally construct the unique features of NiCo 2 S 4. Bimetal synergistic effect and the presence of sulfur atoms can improve the ionic and electron conductivity of NiCo 2 S 4. The unique structure of NiCo 2 S 4 fabricated in such way can allow more active sites exposed to reversible redox reactions, as well as provide relatively short ions/electrons transport pathways within the broken crystal structure and rich porous structure. As such, graphite paper supported NiCo 2 S 4 as a self-supported electrode (NiCo 2 S 4 @EGP) shows an extraordinarily high rate capability with the specific capacitance of 1276 F g−1 at 1 A g−1, and even 1218 F g−1 at 20 A g−1, as well as the excellent cycle stability with capacitance retention of 86 % after 5000 cycles. When assembling into a flexible asymmetric all-solid-state supercapacitor device, this device reaches a high-power density of 55.3 Wh kg−1 at a power density of 747.6 W kg−1, together with a superior high cycle stability (retained 95 % in 5000 cycles). These results obviously open interesting perspectives of using NiCo 2 S 4 @EGP as self-supported electrodes to become an advanced flexible power device. Vertically stacked thorn-like nanostructured NiCo 2 S 4 arrays are designed to in-situ grow on the electrochemical oxidized graphite paper, giving an extraordinarily high rate capability for supercapacitor electrodes with the specific capacitance of 1276 F g−1 at 1 A g−1, and even 1218 F g−1 at 20 A g−1. [Display omitted] [ABSTRACT FROM AUTHOR]