Cyclohexanehexone with ultrahigh capacity as cathode materials for lithium-ion batteries.

Organic carbonyl compounds show potential as cathode materials for lithium-ion batteries (LIBs) but the limited capacities (<600mAhg(-1)) and high solubility in electrolyte restrict their further applications. Herein we report the synthesis and application of cyclohexanehexone (C6O6), which exhibits an ultrahigh capacity of 902mAhg(-1) with an average voltage of 1.7V at 20mAg(-1) in LIBs (corresponding to a high energy density of 1533Whkg(-1)C6O6 ). A preliminary cycling test shows that C6O6 displays a capacity retention of 82% after 100 cycles at 50mAg(-1) because of the limited solubility in high-polarity ionic liquid electrolyte. Furthermore, the combination of DFT calculations and experimental techniques, such as Raman and IR spectroscopy, demonstrates the electrochemical active C=O groups during discharge and charge processes.