First-principles study of the adsorption behaviors of Li atoms and LiF on the CFx(x=1.0, 0.9, 0.8, 0.5, similar to 0.0) surface

摘要

Based on first principles calculation, the adsorption properties of Li atoms and LiF molecules on the fluorographene (CFx) surface with different F/C ratios (x= 1.0, 0.9, 0.8, 0.5 and similar to 0.0) have been studied in the present work. The calculated binding energy of Li and CF(x)is greater than 2.29 eV under different F/C ratios, indicating that the battery has the potential to maintain a high discharge platform during the whole discharge process. But the adsorption energies of LiF on a CF(x)layer for different F/C ratios are 0.12-1.04 eV, which means LiF is not easy to desorb from a CF(x)surface even at room temperature. It will stay on the surface for a long time and affect the subsequent discharge. Current calculations also show the structure of the CFx-skeleton will change greatly during the reaction, when there are many unsaturated carbon atoms on the CF(x)surface, such as atx= 0.8 and 0.5. Moreover, the discharge voltage is strongly dependent on the discharge site. After discharge, the CFx-skeleton may continue to relax and release a lot of heat energy.