Blatter Radicals as Bipolar Materials for Symmetrical Redox-Flow Batteries
Jelte S. Steen, Jules L. Nuismer, Vytautas Eiva, Albert E. T. Wiglema, Nicolas Daub, Johan Hjelm, Edwin Otten
Abstract
substituent are the least affected by water, and moreover, these compounds show >90% capacity retention after charge/discharge cycling in a static H-cell for 7 days (ca. 100 cycles). Testing these materials in a flow regime at a 0.1 M concentration of the active material confirmed the high cycling stability under conditions relevant for RFB operation and demonstrated that polarity inversion in a symmetrical flow battery may be used to rebalance the cell. Chemical synthesis provides insight in the nature of the charged species by spectroscopy and (for the oxidized state) X-ray crystallography. The stability of these compounds in all three states of charge highlights their potential for application in symmetrical organic redox-flow batteries.