Effects of Functional Groups in Redox-Active Organic Molecules: A High-Throughput Screening Approach

Nonaqueous redox flow batteries have attracted recent attention with their potential for high electrochemical storage capacity, with organic electrolytes serving as solvents with a wide electrochemical stability window. Organic molecules can also serve as electroactive species, where molecules with low reduction potentials or high oxidation potentials can provide substantial chemical energy. To identify promising electrolytes in a vast chemical space, high-throughput screening (HTS) of candidate molecules plays an important role, where HTS is used to calculate properties of thousands of molecules and identify a few organic molecules worthy of further attention in battery research. Here, we present reduction and oxidation potentials obtained from HTS of 4178 molecules. The molecules are composed of base groups of five- or six-membered rings with one or two functional groups attached, with the set of possible functional groups including both electron-withdrawing and electron-donating groups. In addition to observing the trends in potentials that result from differences in organic base groups and functional groups, we analyze the effects of molecular characteristics such as multiple bonds, Hammett parameters, and functional group position. This work provides useful guidance in determining how the identities of the base groups and functional groups are correlated with desirable reduction and oxidation potentials.