Two-dimensional materials (2DM) can be engineered as a van der Waals (vdW) “slippery” interface between the electrode and current collector. This arrangement provides less stress build-up and less stress “cycling” on a vdW slippery substrate instead of a fixed interface. For example, silicon (Si) electrode placed over graphene-coated current collector for Lithium-ion batteries (LIBs). The 2DM, such as MXenes, can also be used to replace polymer binders, e.g., in Si-based LIBs. Understanding the interfaces between the electrode and 2D materials is critical for sustainable energy storage in all these cases. This presentation summarizes our latest work on various interface systems – Si/Graphene, Selenium(Se)/Graphene, Si/MXenes. Our DFT studies show more stable performance and much higher Coulombic efficiency for Si films deposited on graphene-coated nickel (i.e., slippery interface) compared to conventional nickel current collectors. The interface strengths of monoclinic Se (0.43 J/m2) and amorphous Si with graphene (0.41 J/m2) are similar in magnitude. The interface strength of c-Se on a 3D Al current collector is higher (0.99 J/m2), suggesting a stronger adhesion. Furthermore, interface strength variation between a-Si and Ti3C2Tx MXenes are determined as the MXenes surface functional groups (Tx) are changed. The Si is interfaced with three Ti3C2 MXene substrates having surface -Oh, -OH and -O mixed, and -F functional groups. Our results reveal that completely hydroxylated Ti3C2 has the highest interface strength of 0.60 J/m2 with a-Si. Our comprehensive interface analysis aims to developed sophisticated 2DM-based electrodes by interface engineering.

Computational study of interface between electrode (selenium, silicon) and 2D materials (graphene, MXenes) for sustainable energy storage

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.