Ion incorporation on the Zr₂CS₂ MXene monolayer towards better-performing rechargeable ion batteries

We study Li and, for the first time, K, Mg and Zn ion intercalation on the surface of the Zr2CS2 MXene monolayer, taking advantage of the fact that the S terminations lower the diffusion barrier of the ions. We find that the Zr2CS2-Li, Zr2CS2-K and Zr2CS2-Mg structures are identical, with only Zr2CS2-Zn differing as to the position of the ion and Zn detaching from the MXene’s surface during migration. Regarding the use of Zr2CS2 as anode material in ion batteries, we examine as criteria the adsorption energy, diffusion barrier energy and open-circuit voltage for each of the ions considered. We show that the K ion has higher mobility, as well as lower open-circuit voltage. These results lead to the fact that KIB have fastest charge/discharge rates and higher energy density than LIB, MIB, and ZIB when it comes to the use of S-terminated, Zr-based materials as negative (anode) electrodes. KIB, therefore, seem the best alternative to LIB, especially after taking under consideration K’s low cost and abundance of resources.