Fig. 4. Optimized structure of (a) P′2-Na_0.67MnO₂ and (b) P′2-Na_0.67Li_0.05Mn_0.95O₂. COHP analysis of the transition metal octahedral sites of (c) P′2-Na_0.67MnO₂ and (d) P′2-Na_0.67Li_0.05Mn_0.95O₂. (e) Na3–Na7 diffusion pathway in P′2-Na_0.67Li_0.05Mn_0.95O₂. (f) activation energy barrier for Na⁺ diffusion in P′2-Na_0.67MnO₂ and P′2-Na_0.67Li_0.05Mn_0.95O₂.