Mi-Soon Lee

A highly durable cross-linked hydroxide ion conducting pore-filling membrane

A highly durable, anion exchange membrane with a uniform thickness of 23.4 μm was fabricated by the pore-filling approach in a porous substrate. The resulting membrane has a hydroxide conductivity in excess of 40 mS cm−1 at 20 °C and does not exhibit significant changes in ion conductivity and IEC in 5 M solution of NaOH at 50 °C for 1500 h.

High power density of reverse electrodialysis with pore-filling ion exchange membranes and a high-open-area spacer

In the present study, a novel reverse electrodialysis (RED) stack with ultrathin lab-made pore-filling membranes and a high-open-area spacer was proposed to enhance the gross power density. The proposed stack had much lower internal resistance than a typical RED stack at optimum flow rates of seawater and river water. Therefore, a gross power density of 2.4 W m−2 was achieved.

A novel amphoteric ion-exchange membrane prepared by the pore-filling technique for vanadium redox flow batteries

A novel amphoteric ion-exchange membrane (AIEM) was prepared through the pore-filling technique, for vanadium redox flow battery (VRBs) applications. Their physico-chemical properties including vanadium ion permeability and electrochemical properties were investigated as a function of cross-linking degrees. Vanadium ion permeability was effectively suppressed by the quaternary ammonium group-induced Donnan exclusion effect and was only 7.7% of that of Nafion117. Finally, open circuit voltage measurements showed that VRBs assembled with the AIEM maintained voltages >1.3 V for over 43 h, which was superior to the cation exchange membranes (CEMs), studied. In addition, the VRBs with AIEM-4 exhibited higher columbic efficiency (ca. 98%) and energy efficiency (ca. 89%) than those with CEMs. Therefore, it may be concluded that pore-filled AIEMs are more suitable for use in VRBs than pore-filled CEMs. This work provides a convenient method for preparing new types of IEMs for various applications.