LAUSR

Abstract There are many advantages for organic compounds to be used as electrode materials of Sodium Ion Batterys (SIBs), such as abundant resources in nature, lower cost in price, and sustainable developments. There is no effective theoretical method to predict the novel organic electrode materials of sodium ion battery now. In this paper, the dispersion-corrected hybrid functional theory (HSE06-D2) method is applied to study an organic compound, thioindigo (SINDIG, C16H8S2O2), which is a novel cathode material of sodium ion battery based on the theoretical calculation results. The two charge/discharge platforms’ potentials and the intermediate state in the charge/discharge process are successfully explored with the theoretical method, which are verified by the CV (cyclic voltammetry) test and ex-situ XRD (X-ray diffraction) measure. The molecular dynamics (MD) simulation results indicate that the sodium ions could diffuse in the molecular crystal lattice along the b-axis direction. The energy storage mechanism of SINDIG could be considered as sodium ions intercalated into the molecular crystal lattice. The theoretical method is proved reliable to predict other novel organic electrode materials, and to explore the mechanism of the energy storage.