S. Maurya, B.L. Davis
Los Alamos National Laboratory,
Keywords: redox flow battery, redox active molecules, grid-scale energy storage, energy storage, beyond lithium
Summary:Non-aqueous flow batteries (NAFBs) are a promising technology for long-term grid-scale energy storage potentially utilizing benefits of non-aqueous medium such as higher cell voltage, potentially higher energy density, and flexible operating temperatures. However, efforts to develop metal-ligand based chemistries to tap the benefits of NAFBs have met with mixed success, and only V(acac)3 based symmetric NAFBs have shown potential for long-term operations. Even so, the solubility of V(acac)3 in non-aqueous solvents is low to compete with their aqueous counterpart. Moreover, modification of V(acac)3 to enhance the solubility has resulted in poor redox cyclability. Moreover, low cell voltages of V(acac)3 are not enough to overcome the additional costs of solvents and electrolytes when compared to aqueous systems. Therefore, it is imperative to operate NAFBs over 3 V, which can increase energy density and lead to significant cost savings. However, considerable research challenges remain in improving the long-term cycling performance and mitigating the lower current density of these non-aqueous systems, let alone the need for high cell voltage redox couples. In this talk, we will discuss the design principle, synthesis, and electrochemical analysis of promising redox active molecules for NAFBs. In addition, we will also discuss membrane development for both aqueous and non-aqueous flow battery systems.