Synthesis of Ni3S2 and MOF-Derived Ni(OH)2 Composite Electrode Materials on Ni Foam for High-Performance Supercapacitors

Abstract

Honeycomb-like Ni(OH)2/Ni3S2/Ni foam (NF) was fabricated via a two-step hydrothermal process and subsequent alkalization. Ni3S2 with a honeycombed structure was in-situ synthesized on the NF surface by a hydrothermal process. MOF-derived Ni(OH)2 nanosheets were then successfully grown on the Ni3S2/NF surface by a second hydrothermal process and alkaline treatment, and a large number of nanosheets were interconnected to form a typical honeycomb-like structure with a large specific surface area and porosity. As a binder-free electrode, the prepared honeycomb-like Ni(OH)2/Ni3S2/NF exhibited a high specific capacitance (2207 F·g−1 at 1 A·g−1, 1929.7 F·g−1 at 5 mV·s−1) and a remarkable rate capability and cycling stability, with 62.3% of the initial value (1 A·g−1) retained at 10 A·g−1 and 90.4% of the initial value (first circle at 50 mV·s−1) retained after 5000 cycles. A hybrid supercapacitor (HSC) was assembled with Ni(OH)2/Ni3S2/NF as the positive electrode and activated carbon (AC) as the negative electrode and exhibited an outstanding energy density of 24.5 Wh·kg−1 at the power density of 375 W·kg−1. These encouraging results render the electrode a potential candidate for energy storage.

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“…Unfortunately, the agglomeration of these catalytic nanoparticles on the substrate is hard to control, resulting in reduced surface area of CNFs. In order to further increase accessible surface area, 3D porous metal substrates (e.g., Ti [23], Ni [24,25], or Fe [26] foam) are often applied for the growth of CNFs. For example, the Ni foam/CNFs electrode exhibits a maximum specific capacitance of 134.3 F g −1 at a scanning rate of 5 mV s −1 [27].…”