Facile Synthesis of Hierarchical Ni7S6 and Co (II)-doped Ni7S6 Flower-structures for High-performance Supercapacitors

A unique 3D flower-like Ni7S6 structure was synthesized through mixed solvothermal method. The as-prepared flower-like Ni7S6 structure with rich active sites demonstrated good supercapacitor performance in alkaline solution. The pure Ni7S6 electrode exhibited high specific capacity (2010 F g−1 at a current density of 1 A g−1), excellent rate performance, and long-term cycling stability owns to its unique structure, which tolerant fast redox in harsh alkaline electrolyte. Additionally, to evaluate the Ni7S6 electrode for practical application in energy storage devices, an asymmetric supercapacitor (ASC) device Ni7S6//AC (activated carbon) were fabricated, and the Ni7S6 electrode prominently enhanced the energy density of ASC can feed a maximum energy density of as well as superior durability with 75.4% retention after 5000 cycles. As compared, the designed Co ions doped Ni7S6 (Co0.7Ni6.3S6) flower was also prepared, and the supercapacitor performances was evaluated furthermore. The results showed that the capacitive performance of pure Ni7S6 electrode is superior to the capacitance of Co (II)-doped Ni7S6 electrode at high current densities. Therefore, the flower-like Ni7S6 electrode material holds a great promise as a potential candidate in high performance supercapacitor device.