T.M. Anderson, H.D. Pratt III
Sandia National Laboratories, United States
pp. 9 - 12
Keywords: ionic liquid, non-aqueous flow battery, membrane
SNL has developed a series of ionic-liquid electrolytes with accompanying non-aqueous compatible membranes and flow cell designs for improved energy density flow batteries targeted to support increasing demands for stationary energy storage. The new electrolytes yield a higher energy density by chemically incorporating an electro-active transition metal element into the solvent’s molecular formula, and they are based on readily available, inexpensive, and non-toxic materials. Although ionic liquids have higher viscosities than conventional non-aqueous electrolytes and water, they are promising for higher energy densities due to higher metal concentrations and wider voltage windows. We have developed a three-fold approach to address high viscosity by developing new materials through careful ligand and anion selection. We have also developed tunable membranes for non-aqueous compatibility and rapid laboratory-scale prototyping to quickly screen materials and cell designs. We are projecting a four-fold improvement in energy density over the next two years through higher voltages and materials that are stable in three or more charge states. We thank the DOE’s Office of Electricity and Dr. Imre Gyuk, Program Manager of the Electrical Energy Storage Program, for their support and funding of the Energy Storage Program.