Understanding Proton-Coupled Electron Transfer to Self-Assembled 3,4,9,10-Perylenetetracarboxylic Dianhydride in Buffered Aqueous Electrolytes

The current battery model is not sustainable for meeting long-term energy storage demands. Lithium-ion batteries, which currently dominate the energy storage market, utilize inorganic electrode materials that are expensive and pose a lithium supply risk, and organic electrolytes, which are expensive, toxic, and combustible. Organic electrode materials and nontoxic aqueous electrolytes solve these problems by decreasing lithium supply risk while improving user safety. In order to optimize this system, the electrochemistry of organic electrode materials in water must first be understood. This work uses buffered electrolytes, cyclic voltammetry, and X-ray spectroscopy to determine whether or not a promising organic electrode material, 3,4,9,10-perylenetetracarboxylic acid (PTCDA), exhibits proton-coupled electron transfer across the pH range in various aqueous electrolytes. Electrolyte components such as buffer molecules and organic cations are found to inhibit expected Nernstian behavior. Overall, understanding the redox chemistry of organic electrode materials in aqueous electrolytes is vital to creating energy storage systems that minimize environmental impact and maximize user safety in the long term.