Insights on Redox Properties of Sumanene Derivatives for High-Performance Organic Cathodes

Despite the potential of large organic molecules for insoluble cathode materials in lithium-ion batteries, they have attracted less attention owing to the penalty in the molecular weight. Herein, an advanced computational modeling approach is employed to comprehensively explore the electrochemical characteristics and theoretical charge/energy storage capability for a series of sumanene derivatives. It is highlighted from this investigation that the carbonyl moiety is generally beneficial to the improvement of the redox properties for the sumanenes. The sumanene with hexagon rings fully functionalized by six carbonyls particularly exhibits both the remarkably high redox potential (3.53 V vs Li/Li⁺) and performance parameters (454 mAh/g and 1129 mWh/g), implying its candidacy as high-potential organic cathodes. It is further demonstrated from a universal relationship of redox potential-electronic property-solvation property that a sumanene derivative would experience a two-stage discharging behavior. This indicates that the sumanene derivative would be cathodically inactive due to a sudden increase of solvation energy.