Papers by Hyung-kwon Hwang
The SiO 2 membranes for polymer electrolyte membrane fuel cell (PEMFC) are preapared by electro-s... more The SiO 2 membranes for polymer electrolyte membrane fuel cell (PEMFC) are preapared by electro-spinning method. It leads to high porosity and surface area of membrane to accommodate the proton conducting materials. The composite membrane was prepared by impregnating of Nafion ionomer into the pores of electrospun SiO 2 membranes. The SiO 2 :heteropolyacid (HPA) nano-particles as a inorganic proton conductor were prepared by microemulsion process and the particles are added to the Nafion ionomer. The characterization of the membranes was confirmed by field emission scanning electron microscope (FE-SEM), thermogravimetry analysis (TGA), and single cell performance test for PEMFC. The Nafion impregnated electrospun SiO 2 membrane showed good thermal stability, satisfactory mechanical properties and high proton conductivity. The addition of the SiO 2 :HPA nano-particle improved proton conductivity of the composite membrane, which allow further extension for operation temperature in low...
Journal of the Korean Electrochemical Society, 2016
Electrospun poly(ether sulfone) (PES) membrane impregnated with Nafion (PES-N) have been develope... more Electrospun poly(ether sulfone) (PES) membrane impregnated with Nafion (PES-N) have been developed for high-temperature polymer-electrolyte membrane fuel cell (HT-PEMFC). The PES-N obtains highly thermal stability up to 430 o C, which is higher than that of the commercial Nafion 212. The PES-N membrane shows a good proton conductivity of about 10 -2 S cm -1 in a temperature range from 75 o C to 120 o C. The membrane-electrode assembly (MEA) with the PES-N membrane exhibits a current density of 1.697 A cm -2 at 75 o C, and 0.813 A cm -2 at 110 o C when the applied voltage is 0.6 V, whereas the MEA with the Nafion 212 membrane shows the current density of 0.647 Acm -2 at 110 o C. The results suggest that the PES-N can be a good candidate for a polymer electrolyte membrane of the HT-PEMFC.
ECS Transactions, 2013
not Available.
Journal of Solid State Electrochemistry, 2011
Proton conducting nanocomposite membranes consisting of poly(vinylidene fluoride-co-chlorotrifluo... more Proton conducting nanocomposite membranes consisting of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(styrene sulfonic acid), i.e., P(VDF-co-CTFE)-g-PSSA graft copolymer and sulfonated silica and were prepared using a sol–gel reaction and subsequent oxidation of a silica precursor, i.e., (3-mercaptopropyl) trimethoxysilane (MPTMS). The successful formation of amorphous phase nanocomposite membranes was confirmed via FT-IR and wide-angle X-ray scattering. All membranes were semi-transparent and mechanically strong, as characterized by a universal tensile machine. Transmission electron microscopy and small-angle X-ray scattering analysis revealed that silica 5–10 nm in size were homogeneously dispersed in the matrix at up to 5 wt.% of MPTMS. At higher concentrations, the silica grew to more than 50 nm in size, which disrupted the microphase-separated structure of the graft copolymer. As a result, both proton conductivity (0.12 S/cm at 25 °C) and single cell performance (1.0 W/cm2 at 75 °C) were maximal at 5 wt.% MPTMS.
International Journal of Hydrogen Energy, 2014
We report on polymer electrolyte membrane fuel cells (PEMFCs) that function at high temperature a... more We report on polymer electrolyte membrane fuel cells (PEMFCs) that function at high temperature and low humidity conditions based on short-side-chain perfluorosulfonic acid ionomer (SSC-PFSA). The PEMFCs fabricated with both SSC-PFSA membrane and ionomer exhibit higher performances than those with long-side-chain (LSC) PFSA at temperatures higher than 100 C. The SSC-PFSA cell delivers 2.43 times higher current density (0.524 A cm À1 ) at a potential of 0.6 V than LSC-PFSA cell at 140 C and 20% relative humidity (RH). Such a higher performance at the elevated temperature is confirmed from the better membrane properties that are effective for an operation of high temperature fuel cell. From the characterization technique of TGA, XRD, FT-IR, water uptake and tensile test, we found that the SSC-PFSA membrane shows thermal stability by higher crystallinity, and chemical/mechanical stability than the LSC-PFSA membrane at high temperature. These fine properties are found to be the factor for applying Aquivion™ E87-05S membrane rather than Nafion ® 212 membrane for a high temperature fuel cell.
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Papers by Hyung-kwon Hwang