Electrochemical performance of interspace-expanded molybdenum disulfide few-layer
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Interspace-expanded molybdenum disulfide (IE-MoS2) has been designed as a supercapacitor electrode material to improve the cycling stability. IE-MoS2 was formed through the ultrasound exfoliation of the interspace-compacted molybdenum disulfide (IC-MoS2), which was initially prepared through hydrothermal synthesis using Na2MoO4 as molybdenum source and CH4N2S as sulfur source. As-formed IE-MoS2 shows a few-layer structure with approximate 8–16 monolayer packing and monolayer distance of 0.83 nm. The MoS2 few-layer distance increased from 12 nm of IC-MoS2 to 20 nm for IE-MoS2. The specific capacitance was determined to be 108 F g−1 for IC-MoS2 to 192 F g−1 for IE-MoS2 at 0.5 A g−1. The improved specific capacitance was ascribed to more active sulfur atom exposed at the edges of IE-MoS2 few-layer to conduct the promoted proton attachment reaction. IE-MoS2 showed the capacity retention of 42% when the current density increased from 0.5 to 10 A g−1, presenting the high-rate capability. IE-MoS2 achieved the capacity retention of 116% at 10 A g−1 after 5000 charge-discharge cycles, which was ascribed to the electro-activation of the few-layer expanded MoS2 in proton acid electrolyte solution. IE-MoS2 exhibited the obviously improved cycling stability in comparison with IC-MoS2. All solid-state IE-MoS2 supercapacitor based on two symmetric IE-MoS2 electrodes and H2SO4-PVA gel electrolyte exhibited the energy density of 18.75 Wh kg−1 and power density of 375 W kg−1 at 0.5 A g−1 and high voltage window of 1.5 V. IE-MoS2 supercapacitor also exhibited the improved capacity retention of 110% after 1000 charge-discharge cycles. Such well-designed IE-MoS2 few-layer with highly improved cycling stability performance presented the promising energy storage application.
KeywordsMolybdenum disulfide Ultrasound exfoliation Cycling stability Electrode material Supercapacitor
The work was supported by National Natural Science Foundation of China (No. 21373047), Graduate Innovation Program of Jiangsu Province, the Fundamental Research Funds for the Central Universities (2242018K41024) and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
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Conflict of interest
The authors declare that they have no conflict of interest.
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