Abstract
A new carbon-coated nickel sulfides electrode material (NST/CNTs@C) has been synthesized through an easy-to-operate process: NiS2/CNTs which was prepared by a hydrothermal method reacted with BTC (1,3,5-benzenetricarboxylic acid) under the condition of water bath heating to obtain the precursor, and then the precursor was calcined in 450 °C under a nitrogen atmosphere to obtain NST/CNTs@C. The electrochemical performance of NST/CNTs@C has been greatly improved because the formation of a carbon-coated layer effectively increased the specific surface area, reduced the charge transport resistance and inhibited the morphological change of nickel sulfides in the charge–discharge process. Compared with pure NiS2 and NiS2/CNTs, NST/CNTs@C presented great specific capacitance (620 F·g−1 at a current density of 1 A·g−1), better cycle stability (49.19% capacitance retention after 1000 cycles) and more superior rate capability (when the current density was raised to 10 A·g−1 the specific capacitance remained 275 F·g−1).
Highlights
Nowadays, with the problems of global warming, fossil energy shortage and environmental pollution, developing and improving the utilization rate of renewable energy has become a research hotspot [1]
On the basis of the energy storage mechanism of electrode materials, SCs can be classified as two types: (1) electrical double-layer capacitors (EDLCs) with carbon materials as the electrode materials; (2) pseudocapacitors (PCs) with transition metal compounds and conducting polymers as the electrode materials [9]
A sample of 1.0 g raw carbon nanotubes (CNTs) (Multi-walled CNTs were purchased from SUSN Limited Company in Shenzhen, China, specific surface area: 85–110 m2 ·g−1, diameter: 20–50 nm.) were added into 100 mL
Summary
With the problems of global warming, fossil energy shortage and environmental pollution, developing and improving the utilization rate of renewable energy has become a research hotspot [1]. Supercapacitors (SCs), as some of the most promising energy storage devices, have received extensive attention, due to their high power and energy density [2], long cycle life [3] and being environmentally friendly [4]. On the basis of the energy storage mechanism of electrode materials, SCs can be classified as two types: (1) electrical double-layer capacitors (EDLCs) with carbon materials as the electrode materials; (2) pseudocapacitors (PCs) with transition metal compounds and conducting polymers as the electrode materials [9]. Transition metal compounds have higher specific capacitance and energy density than carbon materials and conducting polymers because they store energy like carbon materials using double-layer and occur fast and reversible Faradaic redox reaction [10,11]
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