Phenothiazines as One- and Two-Electron Donors for Electrochemical Energy Storage Applications

S.A. Odom, A.P. Kaur, M.D. Casselman
University of Kentucky,
United States

Keywords: redox reaction, electron transfer, catholyte, redox shuttle, redox flow battery

Summary:

Phenothiazines have seen widespread use as stable electron-donating organic compounds with generally stable oxidized states, making them an amenable core for functionalization for electrochemical energy storage applications. Modification of the phenothiazine core provides options to alter redox potentials and improve stability in the neutral, singly oxidized (radical cation), and doubly oxidized (dication) states. Our initial evaluation of these compounds included their use as redox shuttles for overcharge protection of lithium-ion batteries, and more recently, we have targeted one- and two-electron donors for use as electro-active materials in the catholytes of non-aqueous redox flow batteries. Many of our products exhibit extensive stability and high solubility. Some derivatives, including one that can be prepared in one step from commercially-available starting materials, is a liquid at room temperature and dissolves certain lithium salts. This presentation will give an overview of the structures my group has recently prepared, their properties including electrochemical characteristics, and evaluation as catholyte candidates.