Carbon-coated MXene nanofiber as a free-standing electrode for high-performance lithium-ion storage

Because of the excellent conductivity, tunability of elements and surface groups, MXenes are seen as promising electrode materials for lithium-ion storage devices. However, Van der Waals force causes MXene nanosheets to aggregate and re-stack, limiting their applications. Here, we design a carbon-coated MXene nanofiber (C@MXene) free-standing electrode with a 3D conductive network and excellent flexibility to overcome the intrinsic stacking and agglomeration in MXene. Furthermore, the 3D conductive network provides fast lanes for electron transfer, improves the electrochemical activity. And the free-standing electrode structure, which is a straightforward approach for constructing the working electrode and a basis for the following large-scale manufacturing, does not require the auxiliary material and conductive agent to manufacture the electrode material. In particular, the C@V2CTx exhibits outstanding electrochemical performance. At 0.1 A g-1, over 600 mAh g -1 was exhibited after 175 cycles, and over 400 mAh g-1 after 1000 cycles at 2.0 A g-1, cycle retention is close to 100%. Besides, the electrochemical properties of other C@MXene (Nb2CTx, Ti2CTx and VTiCTx) are also optimized to varying degrees. The construction of 3D C@MXene free-standing electrode structure provides a new idea for enhancing the electrochemical performance of MXene.

Automated summary

Due to its excellent conductivity and tunability of elements and surface groups, MXenes are considered as promising electrode materials for lithium-ion storage devices. However, the aggregation and re-stacking of MXene nanosheets caused by Van der Waals force limits their applications. In this study, a carbon-coated MXene nanofiber (C@MXene) free-standing electrode with a 3D conductive network and excellent flexibility was designed to overcome the intrinsic stacking and agglomeration in MXene. The construction of this 3D conductive network not only provides fast lanes for electron transfer but also improves the electrochemical activity of the material.