Unraveling Three‐Stage Discharging Behaviors of Bio‐Inspired Organic Cathode Materials
Ku Hyun Jung, Sohee Lim, Siku Choi, Ki Chul Kim
Abstract
Abstract Despite the creativity in designing materials based on bio‐inspired organic compounds and their potential structural diversity, the incorporation of such materials into cathodes has attracted scarce attention, principally due to intrinsically weak redox activities. Herein, a large number of DNA/RNA‐inspired derivatives are systematically designed, and their electrochemical redox properties are explored with the aim of understanding structure–potential–performance relationship. Four striking conclusions can be drawn from this study. First, charging energy describing the 1st reduction step is a decisive parameter for the open‐circuited adiabatic redox potentials of the compounds in the fully charged states, indicating that reorganization energy in the 2nd reduction step has a negligible impact. Second, both the charging and reorganization energies contribute cooperatively to the discharging potentials. Third, the compounds become cathodically inactive at the end of the discharging process owing to a sudden increase in solvation energy; thus, the compounds exhibit “three‐stage discharging behavior”. Fourth, the charge/energy‐storage capability shows a critical dependence on Li binding mechanism, which is in turn correlated with the afore‐mentioned core factors, leading to exceptional performance for a guanine derivative (1190 and 1586 mWh g −1 ). These findings will aid in advancing the development of bio‐inspired cathode materials for high‐performance Li‐ion batteries.