Cold pressing-built microreactors to thermally manipulate microstructure of MXene film as an anode for high-performance lithium-ion batteries

In order to fully excavate Ti ₃ C ₂ T _x 's electrochemical energy storage capability, a combination of cold pressing and annealing treatment is developed to fabricate free-standing Ti ₃ C ₂ T _x MXene films featuring well-defined film structure, planar macropores, in-plane defects and expanded interlayer spacing. The rational construction of microreactors between Ti ₃ C ₂ T _x nanosheets by cold pressing can assist the formation of the planar macropores and in-plane defects of Ti ₃ C ₂ T _x nanosheets under the annealing conditions, whereas the annealing process could regulate the functional groups of Ti ₃ C ₂ T _x nanosheets to significantly expand their interlayer spacing. These structural advantages not only can prevent self-restacking of Ti ₃ C ₂ T _x nanosheets, but also can increase the ion and electrolyte diffusion as well as the utilization of electrochemically active sites. The as-prepared PF-Ti ₃ C ₂ T _x -500, pre-pressed at 6 MPa followed by an annealing treatment at 500 °C in H ₂ /Ar, exhibits excellent characteristics as the lithium storage anode, such as an enhanced initial Coulombic efficiency (CE) of 77.3%, a high areal capacity (2.22 mA h cm ⁻² at 7.52 mg cm ⁻² for 500 cycles), and stable long cycling performance. This work demonstrates the important role of microstructure manipulation of Ti ₃ C ₂ T _x MXene on their electrochemical performance and can guide future work on designing high-performance MXene-based materials for energy storage applications.