Abstract
Recently, a significant emphasis has been placed on non-aqueous electrolytes for use in redox flow batteries due to their wider electrochemical potential windows, offering higher energy and power densities. To date, several non-aqueous electrolytes using organic molecules [1-2] and metal-ligand complexes [3] have been evaluated for use as electrolytes in non-aqueous redox flow battery (NRFB) systems. With these efforts, substantial performance enhancements, including a several-fold increase in energy density and improved operating temperature range, are possible compared to state-of-the- art vanadium/sulfuric acid flow batteries; however, NRFB progress has been hampered by poor electrolyte stability [4]. Thus far, development has been limited to systems with short cycle-life that exhibit capacity-fade and low current density. This underscores a key challenge currently limiting the advancement of these technologies –
the stability
.
We employ a bio-inspired approach to address the problem of redox-couple instability that impedes commercialization of NRFB. Our strategy of molecular design is based on naturally occurring chelating molecules that have evolved to bind metal ions extraordinarily tightly and with high-specificity. With this approach we have targeted Amavadin, a vanadium compound found in mushrooms of the
Amanita
genus. This molecule, and its analog, calcium vanadium(iv)bis-hydroxyiminodiacetate (CVBH) (Figure 1 inset) are among the most stable vanadium chelates ever elucidated. Initial, static-cell investigations have demonstrated that CVBH is stable to exhaustive, deep redox cycling (Figure 1), making it an excellent candidate for implementation in an NRFB system.
In this presentation we will demonstrate the performance of such an NRFB system, using this mushroom-based (CVBH) electrolyte. Results include battery cycling as well as capacity fade and efficiency analyses. The results of these analyses with respect to various operating conditions and flow cell components will also be reported.
References:
[1] Milshtein, J. D., Kaur, A. P., Casselman, M. D., Kowalski, J. A., Modekrutti, S., Zhang, P. L., Harsha Attanayake, N., Elliott, C. F., Parkin, S. R., Risko, C., Brushett, F. R., Odom, S. A. Energy Environ. Sci. 2016, 9 (11), 3531-3541.
[2] Wei, X., Xu, W., Vijayakumar, M., Cosimbescu, L., Liu, T., Sprenkle, V., Wang, W. Adv. Mater. 2014, 26 (45), 7649-7653.
[3] Suttil, J. A., Kucharyson, J. F., Escalante-Garcia, I. L., Cabrera, P. J., James, B. R., Savinell, R. F., Sanford, M. S., Thompson, L. T. J. Mater. Chem. A 2015, 3 (15), 7929-7938.
[4] Carino, E. V., Staszak-Jirkovsky, J., Assary, R. S., Curtiss, L. A., Markovic, N. M., Brushett, F. R. Chem. Mater. 2016, 28 (8), 2529-2539.
Figure 1