Designing high-voltage carbonyl-containing polycyclic aromatic hydrocarbon cathode materials for Li-ion batteries guided by Clar's theory

Increasing the voltage of organic electrodes is critical in improving their energy density. Here, we examined the correlation between the electron delocalization (aromaticity) and the lithiation voltage of carbonyl-containing polycyclic aromatic hydrocarbons by means of density functional theory computations. Our analyses revealed that the correlation can be well explained by Clar's aromatic sextet theory. An index denoted as Delta C-2Li is introduced to characterize the aromaticity change during lithiation. Several molecules with high Delta C-2Li and high voltage were designed, and we also experimentally investigated a molecule with positive Delta C-2Li as the cathode material. Our results demonstrated the importance and the feasibility of Clar's theory in screening and developing high-voltage organic electrode materials.