• Journal of Radiation Industry
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• v.5 no.2
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• pp.151-157
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• 2011

Crosslinked SPEEK/PVDF membrane were prepared by EB radiation method with various contents of PVDF. The prepared membranes were subjected to a comparative study of proton exchange membranes for fuel cell appreciations. The crosslinked SPEEK/PVDF membranes were characterized by using DMA, DSC and SAXS. The DMA data indicate that the ionic modulus values and cluster $T_g$ decrease with increasing PVDF content. Thus, it was suggested that the number of clustering in the crosslinked membranes can be reduced with increasing PVDF content. The DSC results were shown that the degree of crystalline of the membrane increased with increasing PVDF content. The morphology of the crosslinkied membranes was shown that with increasing PVDF content, the number of crystalline domain of the SPEEK/PVDF membranes increased but ionic aggregation of the membranes decreased. The water uptake behavior, ionic exchange capacity (IEC) and proton conductivity were decreased with increasing PVDF content. The overall findings suggest that the crosslinked membranes offer the possibility for improving the performance of PEMFC, provided that the membranes have thermal and hydration stability.

• Membrane Journal
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• v.14 no.2
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• pp.117-125
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• 2004

Proton exchange membrane composed of PVA/PAM/ZrP was prepared and effect of PAM and ZrP contents on properties and performance of the membrane were investigated. PAM as a crosslinking agent was mixed into PVA solution with different concentration (7∼11 wt%) and the PVA/PAM solution was cast to prepare PVA/PAM crosslinked membrane. The membrane was treated in the solution of zirconyl chloride and phophoric acid to make a PVA/PAM/ZrP composite membrane. Methanol permeability, ion conductivity, swelling and ion exchange capacity of the membranes with different ZrP concentration were $10^{-8}∼l0^{-6}$ $\textrm{cm}^2$/sec, $10^{-3}~10^{-2}$ S/cm, 0.26∼1.17 g $H_2O$/g membrane and 2.59∼5.1 meq/g membrane, respectively. Hethanol permeability and ion conductivity of the PVA/PAM/ZrP membrane were improved by 18% and 23%, respectively, compared to those of the PVA/PAM membrane.

• Journal of the Korean Solar Energy Society
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• v.34 no.4
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• pp.17-22
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• 2014

The design of a fuel cells stack is important to get optimal output power. This study focuses on the evaluation of fuel cell system for unmaned aerial vehicles (UAVs). Low temperature proton exchange membrane (LTPEM) fuel cells are the most promising energy source for the robot applications because of their unique advantages such as high energy density, cold startup, and quick response during operation. In this paper, a 600 W open cathode LTPEM fuel cell was tested to evaluate the performance and to determine optimal operating conditions. The open cathode design reduces the overall size of the system to meet the requirement for robotic application. The cruise power requirement of 600 W was supported entirely by the fuel cell while the additional power requirements during takeoff was extended using a battery. A peak of power of 900 W is possible for 10 mins with a lithium polymer (LiPo) battery. The system was evaluated under various load cycles as well as start-stop cycles. The system response from no load to full load meets the robot platform requirement. The total weigh of the stack was 2 kg, while the overall system, including the fuel processing system and battery, was 4 kg.

• Membrane Journal
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• v.27 no.1
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• pp.53-59
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• 2017

In this study, the composite membranes prepared by sulfonated graphene oxide (sGO) and Nafion were developed as proton exchange membranes (PEMs) for polymer electrolyte membrane fuel cells (PEMFCs). The sGO/Nafion composite membranes were prepared by mixing Nafion solution with the sGO dispersed in a binary solvent system to improve dispersity of sGO. The composite membranes were investigated in terms of ionic conductivity, ion exchange capacity (IEC), FT-IR, TGA and SEM, etc. As a result, the binary solvent system, i.e., ortho-dichlorobenzene (ODB) and N,N-dimethylacetamide (DMAc), were used to obtain high dispersion of sGO particles in Nafion solution, and the ionic conductivity of the sGO/Nafion composite membrane showed $0.06Scm^{-1}$ similar to other research results at lower water uptake, 11 wt%.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.250-255
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• 2012

In this paper, the development and performance analysis of a fuel cell-powered unmanned aerial vehicle is described. A fuel cell system featuring 1 kW proton exchange membrane fuel cell combined with a highly pressurized fuel supply system is proposed. For the higher fuel consumption efficiency and simplification of overall system, dead-end type operation is chosen and each individual system such as purge system, fuel supply system, cooling system is developed. Considering that fluctuation of exterior load makes it hard to stabilize fuel cell performance, the power management system is designed using a fuel cell and lithium-ion battery hybrid system. After integration of individual system, the performance of unmanned aerial vehicle is analyzed using data from flight and laboratory test. In the result, overall system was properly operated but for more duration of flight, research on weight lighting and improvement of fuel efficiency is needed to be progressed.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.323-329
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• 2012

A thermal management system of a proton exchange membrane fuel cell is taken charge of controlling the temperature of fuel cell stack by rejection of electrochemically reacted heat. Two major components of thermal management system are heat exchanger and pump which determines required amount of heat. Since the performance and durability of PEMFC system is sensitive to the operating temperature and temperature distribution inside the stack, it is necessary to control the thermal management system properly under guidance of operating strategy. The control study of the thermal management system is able to be boosted up with hardware in the loop simulation which directly connects the plant simulation with real hardware components. In this study, the plant simulation of fuel cell stack has been developed and the simulation model is connected with virtual data acquisition system. And HIL simulator has been developed to control the coolant supply system for the study of PEMFC thermal management system. The virtual data acquisition system and the HIL simulator are developed under LabVIEWTM Platform and the Simulation interface toolkit integrates the fuel cell plant simulator with the virtual DAQ display and HIL simulator.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.556-560
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• 2013

Recently, there are many efforts focused on development of more economical non-fluorinated membranes for use in PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, characteristics of poly(arylene ether sulfone)(PAES) were compared with fluorinated membrane at PEMFC operation condition. I-V polarization curve, hydrogen crossover, electrochemical surface area, membrane resistance and charge transfer resistance were measured. PAES membrane showed similar performance compared with fluorinated membrane at 100% relative humidity, but the performance of PAES membrane decreased largely due to low ionic conductivity at low relative humidity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.397-403
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• 2015

In this study, water distribution inside a proton exchange membrane fuel cell (PEMFC) was measured experimentally. Water distribution is non-uniform because of vigorous chemical reaction and mass transport and has been difficult to measure experimentally. Therefore, much research relied on indirect measuring methods or numerical simulations. In this study, several mini temperature-humidity sensors were installed at the channel for measuring temperature and humidity of the flowing gas throughout the channel. Only one of two electrode channels was humidified externally, and the humidity distribution on the other side was measured, enabling the observation of water transport characteristics under various conditions. Diffusion through the membrane became more vigorous as the temperature of the humidifier rose, but at high current density, electro-osmotic drag became more effective than diffusion.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.181-186
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• 2016

Recently, there are many efforts focused on development of more economical non-fluorinated membranes for use in PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, characteristics of sulfonated Poly(ether ether ketone) (sPEEK) were compared according to degrees of sulfonation (DS), relative humidity, cell temperatures at PEMFC operation condition. I-V polarization curve, hydrogen crossover, electrochemical surface area, membrane resistance and charge transfer resistance were measured. sPEEK membrane showed high performance at high DS, high temperature and high relative humidity, in particular, performance of sPEEK membrane decreased largely due to low ionic conductivity at low DS and low relative humidity.