FIG. 7A illustrates the performance metrics of an electrode-decoupled Ti—Ce RFB with a quaternized Cardo-poly(etherketone) membrane, 0.5 M TiOSO4/3 M H2SO4 negative electrolyte, 0.5 M Ce(SO4)2/3 M H2SO4 positive electrolyte at a flow rate of 100 mL/min and a 2.5 A current. FIG. 7B illustrates the performance metrics of an electrode-decoupled Ti—Ce RFB with a quaternized Cardo-poly(etherketone) membrane, 0.9 M TiOSO4/4 M CH3SO3H negative electrolyte, 0.9 M Ce(CH3SO3)3/4 M CH3SO3H positive electrolyte at a flow rate of 100 mL/min and a 2.5 A current.
FIG. 8 illustrates a comparison between Ti—Ce redox flow batteries using cation exchange membrane separator (Nafion? 117) and anion exchange membrane separator (Cardo-poly(etherketone)). The Ti—Ce is only electrode-decoupled (i.e., the Ti and Ce ions are hindered from mixing) when using AEM separators. The mixing of Ti and Ce leads to drastic capacity fade as seen in the case of the Nafion? 117 separator.
FIG. 9 illustrates the ability of the Ti—Ce ED-RFB to enable long-duration energy storage. A Ti—Ce RFB was charged to 90% of maximum capacity and stored for 96 hours. The subsequent open circuit voltage measurement of the cell and polarization characterization reveal no loss in performance due to storage.
DETAILED DESCRIPTION
