Due to its unique physical and chemical properties, the 2D material MXenes has attracted a lot of attention in the energy industry and has become a very promising energy storage material. However, MXenes is prone to surface oxidation and interlayer build-up problems, so its energy storage applications are greatly restricted.

Achievements

     Recently, Professor Xu Bin of Beijing University of Chemical Technology published a paper titled " 3D carbon-coated MXene architectures with high and ultrafast lithium / sodium-ion storage " in the internationally renowned journal Energy Storage Materials . A  strategy for directly constructing 2D Ti 3 C 2 T x MXene nanosheets into 3D carbon-coated Ti 3 C 2 T x structures (T-MXene @ C) is proposed. The surface of the original Ti 3 C 2 T x nanosheets was coated with dopamine by self-polymerization , then freeze-dried and carbonized under inert gas to prepare T-MXene @ C nanocomposites. Dopamine self-polymerization not only promotes 2D Ti 3 C 2 T xThe conversion of the sheet into a 3D structure, and the carbon coating layer formed can protect the internal structure from air oxidation. The 3D Tremella-like structure T-MXene @ C has stable surface activity, and its lithium battery and sodium battery exhibit fast charge transfer, ultra-high capacity, superior rate performance and long-term cycling ability. The LIBs of T-MXene @ C showed a capacity of 499.4 mAh g ^-1 at 0.2 C and 101.5 mAh g ^-1 at 100 C. Capacity after 200 cycles was still as high G A 0.05 ^-1 to G mAh 257.6 ^-1 and A G 10 ^-1 is G mAh 77.8 ^-1 . In addition, after 3000 cycles at 1 A g ^-1 , the capacity retention rate was 91.7%, and each cycle was attenuated by 0.00277%, making T-MXene @ C show broad application prospects in energy applications.

Figure  1  Schematic diagram of T-MXene @ C preparation.

Figure  2 The chemical structure of  T-MXene @ C.

Figure  3 Electrochemical performance of  T-MXene @ C -based lithium battery.

Figure  4  Electrochemical kinetics of T-MXene @ C -based lithium battery.

Figure  5  Electrochemical performance of T-MXene @ C based sodium battery.

in conclusion

In summary, a three-dimensional Tremella-like T-MXene @ C structure is reported for negative materials of lithium batteries and sodium batteries. The polymer layer promotes the assembly of the 3D structure of the MXene nanosheets , inhibits the stacking of the nanosheets, and the uniform thin carbon coating formed by the subsequent carbonization helps prevent air oxidation and structural collapse, making its lithium and sodium batteries exhibit Fast charge transfer, ultra-high capacity, superior rate performance and long-term cycling ability. This strategy provides a certain reference for the application of 3D MXenes ( such as V 2 CT x , T 2 CT x ) structures in energy storage, catalysis, sensing, separation membrane and other fields.

Original link:

https://www.sciencedirect.com/science/article/pii/S2405829720301367

Source: MXene Academic