Metal Coordination Complexes for Flow Batteries

Flow batteries are excellent candidates for use in long-duration, grid, and industrial scale energy storage applications. Conventional flow batteries employ aqueous, metal-based electrolytes and come with a variety of challenges, including low-energy densities and high cost. Metal coordination complexes (MCCs) based on inexpensive metals show promise for use as active materials. The diversity of metal-ligand structures allows key properties of the MCC, such as the redox potential and solubility, to be tuned. These advantages could result in higher energy densities and lower costs compared to other metal-based electrolytes. MCCs have been investigated for use in aqueous or non-aqueous electrolytes. This chapter provides a brief overview of MCCs, their key features, and their development for use in aqueous and non-aqueous flow batteries.