Rational Design of Self-Supported Ni3S2 Nanosheets Array for Advanced Asymmetric Supercapacitor with a Superior Energy Density
2017
Chen, Jun Song | Guan, Cao | Gui, Yang | Blackwood, Daniel John
We report a rationally designed two-step method to fabricate self-supported Ni₃S₂ nanosheet arrays. We first used 2-methylimidazole (2-MI), an organic molecule commonly served as organic linkers in metal–organic frameworks (MOFs), to synthesize an α-Ni(OH)₂ nanosheet array as a precursor, followed by its hydrothermal sulfidization into Ni₃S₂. The resulting Ni₃S₂ nanosheet array demonstrated superior supercapacitance properties, with a very high capacitance of about 1,000 F g–¹ being delivered at a high current density of 50 A g–¹ for 20,000 charge–discharge cycles. This performance is unparalleled by other reported nickel sulfide-based supercapacitors and is also advantageous compared to other nickel-based materials such as NiO and Ni(OH)₂. An asymmetric supercapacitor was then established, exhibiting a very stable capacitance of about 200 F g–¹ at a high current density of 10 A g–¹ for 10,000 cycles and a surprisingly high energy density of 202 W h kg–¹. This value is comparable to that of the lithium-ion batteries, i.e., 180 W h kg–¹. The potential of the material for practical applications was evaluated by building a quasi-solid-state asymmetric supercapacitor which showed good flexibility and power output, and two of these devices connected in series were able to power up 18 green light-emitting diodes.
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