. Here, a 0 is the lattice constant of the bare-MXene, and a is the lattice constant of Li/Mg adsorbed material. We calculated the strains of the single ion adsorbed monolayers (Ti 2 CSTA 0.0625 ) and the MXenes with double Li/Mg ion layers (Ti 2 CSTA 2 ). It is clear from Table that ∆a is negligible for all the electrodes when a single ion is adsorbed. All the strains are less than 0.3 % for Ti 2 CSTA 0.0625 compounds. But, ∆a is considerable or negligible depending on the type of A and T atoms. Surprisingly, Ti 2 CSOLi 2 has no strain found. On the contrary, ∆a is around 1.2 % for Ti 2 CSOMg 2 . Ti 2 CSSeLi 2 exhibits the largest ∆a (4.1 %) in Table . Ti 2 CSSeMg 2 shows ∆a ≈ 2.3 %. Thus we can expect very low surface expansion in Ti 2 CSO MXenes compared to Ti 2 CSSe MXenes. We also computed the out-of-plane strain (∆t) by determining the thickness of the MXenes, as shown in Table . Even though the in-plane strain is very low in Ti 2 CSOA 2 monolayers, the out-of-plane strain is considerable. On the contrary, ∆t values of Ti 2 CSSeA 2 MXenes is more than three times lower than that of O-based counterparts. As will be explained later, Ti 2 CSOLi 2 , Ti 2 CSOMg 2 and Ti 2 CSSeLi 2 are thermodynamically stable. Therefore, we carried ab-initio MD simulations using VASP to investigate the stability of those materials at high temperatures. Our MD simulations were performed based on the isothermal-isobaric (NPT) ensemble at 400 K temperature, which is way higher than the room temperature. The MD simulations were carried out with 4 × 4 supercells for 5 ps. The total energy and the temperature variations in Fig. suggest that those materials are stable at 400 K. This provides the evidence that Ti 2 CSOLi 2 , Ti 2 CSSeLi 2 and Ti 2 CSOLi 2 MXenes can exist at room temperature. We did not observe any bond breaking or formation of Li x S.