Polycarbonyl(quinonyl) organic compounds as cathode materials for sustainable lithium ion batteries

Suitably designed organic compounds are promising renewable electrode materials for lithium ion batteries (LIBs) with minimal environmental impacts and no CO2 release. Herein we report a series of polycarbonyl organic compounds with different number of hydroxyl groups, which can be obtained from renewable plants, as cathode materials for LIBs. Density functional theory (DFT) calculations based on the natural bond orbital (NBO) reveal a positive correlation between the reduction potentials and the number of hydroxyl groups, which is borne out experimentally. Anthraquinone (AQ) with three or four -OH groups has the structural advantages for improving the discharge plateaus. Mechanistic studies show that AQ containing neighbouring carbonyl groups and hydroxyl groups facilitates the formation of six or five-membered rings with lithium ion. Charge/discharge tests show that AQ, 1,5-DHAQ, 1,2,7-THAQ, and 1,2,5,8-THAQ can achieve initial discharge capacities of 215, 190, 186 and 180 mAh g-1 at a current density of 20 mA g-1, corresponding to 84%, 85%, 89% and 91% of their theoretical capacities, respectively.