Tae-Ho Kim

Preparation and properties of sulfonated poly(arylene ether sulfone)/hydrophilic oligomer- g -CNT composite membranes for PEMFC

AbstractWe have synthesized a novel composite membrane composed of hydrophilic oligomer-g-carbon nanotube (CNT) and sulfonated poly(arylene ether sulfone) (sPAES) for proton exchange membrane fuel cell (PEMFC). Hydrophilic oligomer-g-CNT is made by linking sPAES hydrophilic oligomers of either 3 k, 7 k, or 15 k molecular weight to CNTs. Hydrophilic oligomers allow better dispersion of CNTs in the polymer matrix, and the well dispersed CNTs act as a reinforcing agent in the membrane. The sulfonic acid groups on the hydrophilic oligomer-g-CNT form effective water transport channels which can hold more water under low humidity conditions. Therefore, the developed composite membrane shows proton conductivity enhancement of 40% compared to the pristine membrane at 80 °C and 50% relative humidity (RH) condition. Single cell performances and mechanical properties are also improved in the composite membrane. Especially, current density of the composite membrane prepared with 1 wt% hydrophilic oligomer (15 k)-g-CNT shows an 86% increase compared to that of the pristine membrane at 0.6 V, 80 °C, and 50% RH condition.n

Intrinsically microporous polymer-based hierarchical nanostructuring of electrodes via nonsolvent-induced phase separation for high-performance supercapacitors

The growing demands of next-generation applications for high power and energy sources necessitate advances in hierarchically porous carbon-based energy storage materials, which improve the overall kinetics of electrolytic reactions by providing efficient ion and electron transport pathways and facilitate electrolyte infiltration into the electrode during charging/discharging. Herein, we fabricate hierarchically structured porous carbon electrodes (cNPIM), prepared by solution casting of a polymer of intrinsic microporosity (PIM-1) followed by nonsolvent-induced phase separation and carbonization. The obtained material exhibits a considerable surface area (∼2100 m2 g−1), high electrical conductivity (150 S cm−1), high specific capacitances (345, 235, and 195 F g−1 in three-, two-electrode aqueous systems, and two-electrode organic systems, respectively) at 1 A g−1, and an exceptional specific energy of 43.2 W h kg−1 at a specific power of 1.25 kW kg−1, featuring a pore size gradient in the surface normal direction.