Flexible reduced graphene oxide (rGO) sheets are widely used in portable electronic devices and flexible energy storage systems. However , the poor mechanical properties and electrical conductivity of rGO tablets have seriously restricted its development. Although the mechanical properties of rGO sheets can be improved through different interfacial interactions, such as hydrogen bonding, ionic bonding, π-π interaction, and covalent bonding , it is still difficult to balance the mechanical properties and conductive properties simultaneously.

Achievements

    Recently, Professor Cheng Qunfeng of Beijing University of Aeronautics and Astronautics published a paper entitled " Super-tough MXene-functionalized graphene sheets " in the top international journal Nature Communications . Using MXene nanosheets to achieve the functionalization of rGO nanosheets through Ti-OC covalent bonds, thereby obtaining MrGO. MrGO tablets are cross-linked by a cross-linking agent (1-aminopyrene-disuccinimidyl suberate, AD). The introduction of MXene nanosheets and AD molecules reduces the voids in the graphene sheets and improves the arrangement of the graphene sheets, thereby greatly improving the compactness and high toughness of the graphene sheets. In-situ Raman spectroscopy and molecular dynamics modes reveal the synergetic interface mechanism of Ti-OC covalent bonds, interlayer slip and π stacking of MXene nanosheets. The super-toughness MXene functionalized graphene sheet assembled supercapacitors also show extremely high energy and power density.

Figure  1 Schematic diagram of preparation of  MrGO tablets.

Figure  2  Mechanical properties of MrGO tablets.

Figure  3  The toughening mechanism of MrGO tablets.

Figure  4  shows the electrochemical performance of its supercapacitor.

Figure  5  Bending test of its supercapacitor.

in conclusion

In this work, nanosheets with high strength, ultra-high toughness and excellent electrical conductivity were prepared by MXene functionalized graphene. The assembled flexible supercapacitor has an ultra-high volume energy density ( ~ 13.0 mWh cm ^-3 ). After 17,000 bending cycles at 0 o to 180 o , the capacity retention rate is still ~ 98% . This functionalized graphene strategy provides new ideas for the preparation of two-dimensional composite thin film materials with excellent mechanical and electrical properties.

Original link:

https://www.nature.com/articles/s41467-020-15991-6.pdf

Source: MXene Academic