fig4

Figure 4. Binding energies and structural changes for 2L Li/Na intercalation in GCs. (A) Schematic diagrams for ground-state MXene heterostructures intercalated by 2L Li/Na, in which the 2nd layer Li/Na atoms locate at high-symmetry sites A, B and C, respectively, orange balls represent the 1st layer Li/Na atoms, and pink balls represent the 2nd layer Li/Na atoms. Ground states mostly exhibit in sites B (or A) locating upon C atoms; (B) E_B per Li atom for 2L Li intercalation; (C) E_B per Li atom of the 2nd layer intercalated Li; (D) ΔV, (E) ΔZ and (F) ΔS for 2L Li intercalation; (G) E_B per Na atom for 2L Na intercalation; (H) E_B per Na atom of the 2nd layer intercalated Na, (I) ΔV, (J) ΔZ and (K) ΔS for 2L Na intercalation. (B-F) share the same legend, and so do (G-K). GCs: Ground-state configurations.