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Synergistically Active NiCo2S4 Nanoparticles Coupled with Holey Defect Graphene Hydrogel for High-Performance Solid-State Supercapacitors

Research paper by Sintayehu Nibret Tiruneh, Dr. Bong Kyun Kang, Sung Hoon Kwag, YoungHun Lee, MinSeob Kim, Prof. Dae Ho Yoon

Indexed on: 02 Feb '18Published on: 01 Feb '18Published in: Chemistry - A European Journal



Abstract

Nickel cobalt sulfide nanoparticles embedded in holey defect graphene hydrogel (HGH) that exhibit highly porous structures and uniform nickel cobalt sulfide nanoparticle sizes are successfully prepared by a facile solvothermal–hydrothermal method. As an electrode material for supercapacitors, the as-prepared NiCo2S4@HGH shows ultra-high specific capacitances of 1000 F g−1 and 800 F g−1 at 0.5 and 6 A g−1, respectively, owing to the outstanding electrical conductivity of HGH and high specific capacitance of NiCo2S4. After 2100 charge/discharge cycles at a current density of 6 A g−1, 96.6 % of the specific capacitance was retained, signifying the superb durability of NiCo2S4@HGH. Moreover, remarkable specific capacitance (312.6 F g−1) and capacity retention (87 % after 5000 cycles) at 6 A g−1 were displayed by the symmetric solid-state supercapacitor fabricated by using NiCo2S4@HGH electrodes. These auspicious supercapacitor performances demonstrate that the as-developed solvothermal–hydrothermal approach can be widely used to prepare graphene-coupled binary metal sulfides for high-performance supercapacitor applications.