Elucidating the Origin of the Low Anion Intercalation Potential of Graphene-like Graphite: A DFT Study

Graphene-likegraphite (GLG) exhibits significantly large capacityas a cathode material for dual-ion batteries (DIBs) because the anionintercalation reaction proceeds from a lower potential than that ofgraphite. In this study, the factors contributing to the characteristiclow anion intercalation potential of GLG were investigated by densityfunctional theory (DFT) calculations. Ketone-, lactone-, and ether-introducedgraphites were used as models of GLG. The GLGs exhibited lower interlayerexpansion energies than graphite, but their contribution to loweringthe anion intercalation potential was quantitatively limited. On theother hand, the density of states (DOS) of the GLGs showed new bandsat or below the Fermi level, indicating that the electron withdrawalfrom the host material can proceed from a lower potential. In addition,the energy and peak intensity of the bands correlated with the degreeof lowering of the calculated anion intercalation potentials. Therefore,it was concluded that the change in the electronic state caused bythe introduction of the oxygen-containing functional groups is themain cause of the characteristic low anion intercalation potentialof GLG.