Insights into Hydrotropic Solubilization for Hybrid Ion Redox Flow Batteries
Ding, Y (Ding, Yu)[ 1,2 ] ; Zhang, CK (Zhang, Changkun)[ 1,2 ] ; Zhang, LY (Zhang, Leyuan)[ 1,2 ] ; Wei, HY (Wei, Haiyan)[ 3 ] ; Li, YF (Li, Yafei)[ 3 ]*（李亚飞）; Yu, GH (Yu, Guihua)[ 1,2 ]*
[ 1 ] Univ Texas Austin, Mat Sci & Engn Program, Austin, TX 78712 USA
[ 2 ] Univ Texas Austin, Dept Mech Engn, Austin, TX 78712 USA
[ 3 ] Nanjing Normal Univ, Sch Chem & Mat Sci, Jiangsu Key Lab New Power Batteries, Nanjing 210023, Jiangsu, Peoples R China
ACS ENERGY LETTERS，201811,3(11),2641-2648
Inspired by the solubility enhancement in pharmaceutical research, we report a redox flow battery enabled by hydrotropic solubilization. An almost 3-fold increase in the solubility of hydroquinone (H(2)BQ)-based catholyte can be achieved by employing urea as a hydrotropic agent, and the universal effect of urea on a variety of organic redox species has been demonstrated as well. By combining chemical characterization and computational modeling, the molecular interactions between solute, solvent, and hydro tropic agent are elucidated to shed light on the hydrotropic mechanism. Moreover, the working potential of the flow battery can be improved by adopting deep eutectic solvents (DESs) as anolytes. The hydrotropic solubilization leads to an energy density of 114 Wh L-1 when pairing the catholyte with a Li anode, and the energy density can still reach 25.3 Wh L-1 in the proof-of-concept hybrid ion flow battery.