(607d) First-Principles Modeling of Redox Potential of Organic Materials for Lithium-Ion Batteries

In this talk, we present the first-principles density functional theory modeling of redox properties of various organic materials as positive electrode materials for lithium-ion batteries. First, from the density functional theory (DFT) calculations to understand the binding behaviors of Li atoms interacting with the quinone derivatives, we find that the Li atoms prefer to bind with the carbonyl groups in the molecules. Next, we observe that the redox properties of organic materials can be harnessed by designing their chemical structures. In particular, introducing electron-withdrawing functional groups is beneficial to enhance the redox potential. In addition, we present the change in the redox properties of organic materials as a function of the number of bound Li atoms, which would be related to the change of redox characteristics during the discharging process. In general, the redox potential is decreased with increasing the number of bound Li atoms, meaning that the charge capacity is limited by the number of carbonyl groups. However, it should be noted that the functionalization of organic materials with carboxylic acids can improve their charge capacity. Through this study, it is highlighted that the cathodic activity of organic materials during the discharging process relies strongly on the solvation effect as well as on the number of carbonyl groups available for further Li binding.