Angew.｜Preparation of MXene-Cu/Co composites from molten salts for symmetric supercapacitors

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Research abstract

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The intrinsic metallic conductivity, high density, and hydrophilicity of MXenes make MXenes a promising supercapacitor electrode material. In view of this, the team of Professor Pang Huan of Yangzhou University published research results in "Angew. Chem. Int. Ed.", reporting a Ti3C2-Cu/Co composite obtained by molten salt etching method, in which metal atoms and their The interaction of MXene is achieved through surface O atoms, which was confirmed for the first time by XAFS characterization technique. The electrochemical performance of the Ti3C2-Cu electrode is dominated by the pseudocapacitance contribution of Cu, and a high specific capacitance of 885 F/g can be achieved in 1.0 M sulfuric acid electrolyte at a current density of 0.5 A/g. The working voltage of the Ti3C2-Cu//Ti3C2-Cu symmetric supercapacitor can reach 1.6 V, the capacitance can reach 290.5 mF/cm2 under the condition of 1 mA/cm2, and the cycle stability exceeds 10,000 times. The energy density of soft-pack supercapacitor-based devices can reach 103.0 μWh/cm2 at a power density of 0.8 mW/cm2. This work provides new insights into the molten salt etching mechanism and strategy of MXene-based materials for electrochemical energy storage.

Graphical guide



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Figure 1. Preparation and microstructure characterization of Ti3C2-Cu/Co composites.


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Figure 2. XR spectra of Ti3AlC2 and Ti3C2-Cu/Co composites, high-resolution Ti 2p, C 1s, Cu 2p and Co 2p XPS spectra; X-ray edge absorption of metallic Cu and Co.



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Figure 3. Electrochemical performance measurement and kinetic analysis of Ti3C2-Cu in sulfuric acid electrolyte.



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Figure 4. Electrochemical performance test of Ti3C2-Cu//Ti3C2-Cu symmetric supercapacitors.



Summarize

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Without the presence of -F functional groups, the unique intercalation structure and the synergistic effect between Ti3C2 and Cu enable Ti3C2-Cu to exhibit excellent electrochemical performance as a supercapacitor electrode. Different from single metal atom modification, Cu/Co interacts with O atoms in surface functional groups as metal particles/clusters in the layered structure of MXene, that is, connects with Ti3C2 through Cu-O and Co-O bonds. The slight bonding between the intercalated metal and MXene enables the composite to exhibit excellent stability during high-rate charge-discharge, which can prevent the metal clusters from falling off. At the same time, considering that O functional groups can be used as active adsorption sites for protons, the capacitance of O-rich MXenes is also higher than that of F functionalized MXenes.


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Literature link

https://doi.org/10.1002/anie.202112381

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