Recently, Wu Zhongshuai, a researcher of the two-dimensional material and energy device research group of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and Wang Xiaohui, a researcher of the Institute of Metal Research of the Chinese Academy of Sciences, used a two-dimensional metal carbide MXene as the negative electrode and carbon nanotubes as the positive electrode with redox activity Hydroquinone was used as a positive electrode electrolyte additive, and a hydrogen ion "rocking chair" type high specific energy supercapacitor was constructed. The related results were published in "ACS Nano".
MXene is a two-dimensional metal carbon (nitrogen) compound nanosheet with high volume specific capacity (1500F / cm3) and high-quality specific capacity (380F / g). It is a very promising electrode material for supercapacitors. However, most of the current reports are water-system symmetrical supercapacitors, which have the problem of a narrow operating voltage window (typically 0.6 V), resulting in a lower energy density. Therefore, in order to give full play to the characteristics of MXene's high specific capacity, it is urgent to develop high-voltage supercapacitors to obtain high energy density.
Recently, the research team used Ti3C2Tx MXene as the negative electrode, carbon nanotubes as the positive electrode, sulfuric acid solution and sulfuric acid-hydroquinone mixture liquid as the negative electrode and the positive electrode electrolyte respectively, and a proton-selective Nafion membrane as the separator to construct hydrogen. Ion "rocking chair" type asymmetric supercapacitor. During charge and discharge, reversible deprotonation and protonation of hydroquinone adsorbed on the carbon nanotubes provide high pseudocapacitance for the positive electrode; meanwhile, with the insertion and extraction of hydrogen ions from the negative electrode, Ti3C2Tx The titanium element undergoes a reversible redox reaction. The obtained MXene-based asymmetric supercapacitor not only realizes the reversible and rapid movement of hydrogen ions between the positive and negative electrodes, but also has a high operating voltage of 1.6V and a high energy density of 62Wh / kg, which is currently reported as the MXene-based super system of the water system. The highest value of the capacitor. This work provides new ideas for the construction of MXene-based asymmetric, high specific energy supercapacitors.
The above work was supported by the National Natural Science Foundation of China and the National Key R & D Program.
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