Theoretical study on the electric-double layer formed at interlayer of transition-metal-carbide MXene by quantum-classical hybrid interface simulation

Two-dimensional transition-metal carbide MXene has been known as a promising material of high-performance electrode for energy storage applications with both non-aqueous and aqueous electrolytes because it has electronic conductivity, ion capability in interlayer nanospace, and the redox activity of Ti.
Here, we performed a microscopic theoretical analysis of the electric-double layer capacitance in the interlayer nanospace of the MXene electrode by combining first-principles calculations and implicit solvation theory named 3D-RISM method[1]. As a result, we found that hydration shell of Li⁺ and Na⁺ overscreens the electric field, or shows “negative dielectric constant”, and enhances its electronic-double layer capacity[2, 3].

[1] S. Nishihara, and M. Otani, Phys. Rev. B 96, 115429 (2017).
[2] A. Sugahara, Y. Ando, S. Kajiyama, K. Gotoh, K. Yazawa, M. Otani, M. Okubo, and A. Yamada, Nat. Commun. 10, 850 (2019).
[3] K. Kim, Y. Ando, A. Sugahara, S. Ko, Y. Yamada, M. Otani, M. Okubo, and A. Yamada, Chem. Mater. 31, 5190 (2019).