Li charge transfer simulation at graphite/solution interface using density functional calculation combined with implicit solvation model

Because charge transfer reactions at electrode/solution interfaces limits the performance of lithium-ion batteries (LIBs), it is considered that Li insertion/desorption reaction at the interface between graphite anode and electrolyte solution. Density functional theory + effective screening medium (ESM) method combined with reference interaction site model (RISM), ESM-RISM [1], is applicable to the charge transfer reaction because the chemical potential of electrons (µ_e) corresponds to an electrode potential [2] and the distribution function of the solvation is automatically formulated for the solvation/desolvation structures. The reacting Li is moved from the stable site in graphite to the bulk solution region. The constant-µ_e ESM-RISM simulations show that the assuming Li path is accompanied by an electron transfer process. The activation energy at equilibrium potential is approximately 0.6 eV[3], which is consistent with experiments. The dependences of the activation energy and the surface charge density according to the Li content x (LixC6, x=0, 0.5, 1) are further discussed. [1] S. Nishihara and M. Otani, PRB 96, 115429 (2017). [2] J. Haruyama, T. Ikeshoji, and M. Otani, PRM 2, 095801 (2018). [3] J. Haruyama, T. Ikeshoji, and M. Otani, J. Phys. Chem. C 122, 9804 (2018).