Understanding 3D/2D Interfaces for Ion Battery Technologies

Composites and heterostructures composed of 3D bulk layered with two dimensional (2D) materials are actively being utilized in energy technologies for enhanced performance, mechanical stability and flexibility. 2D materials such as graphene and transition metal carbides (MXenes) provide a mechanically stable skeleton to high volumetric capacity electrodes such as silicon(Si), selenium(Se) and tin(Sn) to name a few. The physical and chemical attributes of the formed 3D/2D interfaces directly propels the electrochemical performance of the composite electrode. We utilize Density functional theory (DFT) to quantify the strength of 3D/2D interfaces formed and further corelated the interface strength to the crystal structure, surface chemistry and electrochemistry of the electrodes. We investigate the interface strength variations between amorphous Si and Ti3C2Tx MXene as the MXene surface functional groups (Tx) are varied from -OH to -OH/O mixed, and -F. The Si/MXene interface is further compared with Si/Graphene interface for Lithium ion battery applications. In additional, ability of Deep Learning(DP) potential to accurately describe structural and dynamic properties of such interfaces has been explored. A DP based potential is generated from vast 3D/2D interface dataset from quantum mechanical calculations and its accuracy has been compared with DFT output of interface dynamics. Issues related to the development of DP for such systems will also be discussed.