Fabrication of new Mn-based MXene structure from MnO2 for electrochemical energy storage applications

Abstract

MXene compound of Mn₇C₃ was successfully prepared using combined mechanical, thermal, and leaching processes. A mixture of MnO₂, Al, and black C with stoichiometric ratios 3:5:2 was mechanically activated in the ball mill for 5 h. Thermal treatment at 1000 °C was applied to this mixture. Magnetic separation was used to separate Mn₃AlC₂ from Al₂O₃. After that, Al was leached from Mn₃AlC₂ using 15% HF. SEM investigation indicated the formation of Mxene (Mn₇C₃) particles as aligned sheet-like structure and particle size distribution range of 110–145 nm. The obtained MXene compounds were used as an active material vs. lithium metal and assembled in a coin cell. The electrochemical assessment of this cell was carried out using galvanostatic cycling, electrochemical impedance spectroscopy, and cyclic voltammetry techniques. MXene (Mn₇C₃) cell showed better performance with charge capacity by preserving about 150 mAh g⁻¹ after 100 cycles. The coulombic efficiency of the cell is approaching 99.2% after long cycles.

Graphical abstract