The multi-layer hexagonal hole MXene electrode material was constructed by using the carbon vacancy defect ordering strategy,and the energy density of 235.8 Wh·kg-1 in the soft-pack supercapacitor was realized at the power density of 6 480 W·kg-1.The electrode material has a structure of three-dimensional hexagonal holes,which increases the contact area with the electrolyte and provides more active sites for potassium ion storage.Combined with the pseudo-capacitance effect caused by the change of valency of newly exposed titanium atoms in the inner wall of the hexagonal hole,the internal reason for the increase of specific capacity of multi-layer hexagonal hole MXene water system potassium ion supercapacitor is explained.The adsorption energy of multi-layer hexagonal porous MXene for potassium ion was calculated by density functional theory,and the optimal position of potassium ion adsorption was determined by electrochemical potassium storage experiment and kinetic analysis,and the adsorption law of potassium ion was obtained.By a quantitative analysis of the band structure and differential charge density of electrons in multi-layer hexagonal hole MXene,the internal mechanism of high conductivity and good magnification performance of the water system potassium ion supercapacitor is revealed.
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