(546f) Investigating Ion Intercalation Mechanisms in Mxene Structures through Molecular Dynamics Simulations

Supercapacitors are electrical energy storage devices that have garnered much interest in recent decades due to their high power density in comparison to conventional batteries[1]. Though they play important roles in various fields, the lower energy density of supercapacitors limit their widespread application. In an effort to enhance the energy density of supercapacitors, various novel materials have been synthesized and studied as electrodes. MXenes, a new family of 2D transition metal carbides, have attracted particular interest due to their excellent pseudocapacitance originating from redox reactions at the interface.[2] Studies have shown that the process of ion intercalation can significantly enhance the specific capacitance of MXenes[3]. As a result, it is of fundamental importance to understand the microscopic behavior of ions under the confinement of MXenes.

Through a series of molecular dynamics simulations, we study the atomistic interactions between ions and the MXene surface throughout the process of ion intercalation. By analyzing various structural and transport properties, such as the coordination number and the dynamics of the solvation cages, we aim to understand how ion intercalation affects the interlayer spacings of MXenes. Additionally, the constant potential method is utilized to study how ion behavior is impacted by potentials of varying magnitude. Overall, a detailed understanding of ion solvation behavior at a wide range of potentials can further guide the design of MXene supercapacitors that display simultaneous high power density and energy density.

[1] Miller J R, Outlaw R A, Holloway B C. Graphene Double-Layer Capacitor with Ac Line-Filtering Performance. Science, 2010, 329(5999):1637-1639

[2] Lukatskaya M R, Mashtalir O, Ren C E, et al. Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide. Science, 2013, 341(6153):1502-1505

[3] Li J, Yuan X, Lin C, et al. Achieving High Pseudocapacitance of 2d Titanium Carbide (Mxene) by Cation Intercalation and Surface Modification. Advanced Energy Materials, 2017, 7(15):1602725