Browsing by Author "Lin, Jiunn-Nan"

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Characteristics of high-water-uptake activated carbon/Nafion hybrid membranes for proton exchange membrane fuel cells
(2013-03-15)
Chien, Hung-Chung
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Tsai, Li-Duan
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Lai, Chien-Ming
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Lin, Jiunn-Nan
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Zhu, Chao-Yuan
A cost-effective and high-throughput method for producing high-water-uptake membranes is developed by combining high-porosity and superior-surface-area activated carbon with Nation. The resultant activated carbon/Nafion hybrid composite exhibits high water uptake and an improved proton conductivity, which can be exploited in a proton exchange membrane fuel cell (PEMFC). This hybrid membrane displays a superior performance to that of the commercial Nation 211 when used in fuel-cell measurements. Electrochemical impedance spectroscopy (EIS) is used to simulate the changes in resistance during the operation of the fuel cells and conclusively explains the improved performance of the composite membranes. (C) 2012 Elsevier B.V. All rights reserved.
Highly hydrated Nafion/activated carbon hybrids
(2012-10-12)
Chien, Hung-Chung
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Tsai, Li-Duan
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Kelarakis, Antonios
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Lai, Chien-Ming
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Lin, Jiunn-Nan
The incorporation of highly porous activated carbon (aC) to Nafion membranes confers unprecedented levels of water uptake (4 times higher for 10 wt% aC compared to neat Nafion) at a minimal dimensional swelling and results in dramatic enhancements in ionic conductivity at low relative humidity. This behavior reveals the development of a robust network of water nanochannels formed by the carbon pores and the polymeric ionic domains which are structurally stabilized by the rigid Nafion backbone and the non-deformable aC particles. (c) 2012 Elsevier Ltd. All rights reserved.
Novel Bilayer Composite Membrane for Passive Direct Methanol Fuel Cells with Pure Methanol
(2013-07-01)
Tsai, Li-Duan
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Chien, Hung-Chung
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Huang, Wei-Han
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Huang, Chiu-Ping
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Kang, Chi-yun
The bilayer composite membrane composed of the sulfonated graphene oxide (SGO)/Nafion and sulfonated activated carbon (SAC)/Nafion composite membrane is designed and prepared by repeatedly bar-coating. With the carefully chosen of solvent, the bilayer composite membrane has shown identical thickness on SEM observation. The SGO/Nafion side has a low methanol permeability ascribed to the unique selectivity of the SGO. Moreover, the SAC side has good water retention which can facilitate the back diffusion water produced by the cathode. The unique design of composite membranes confers low methanol crossover and high proton conductivity at the same time. The bilayer composite membrane shows better power density than Nafion 212 and Nafion 115 and the performance monitored for 24h to ensure the stable power density and the durability of the membrane.
Poly(ethylene glycol) modified activated carbon for high performance proton exchange membrane fuel cells
(2013-08-30)
Tsai, Li-Duan
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Chien, Hung-Chung
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Wang, Cheng-Hong
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Lai, Chien-Ming
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Lin, Jiunn-Nan
A high water retention membrane is developed by co-assembling poly(ethylene glycol) (PEG) grafted activated carbon (AC-PEG) with Nafion. The AC-PEG is prepared via a sol gel process. The use of PEG as a transporting medium in AC-PEG shows a largely improved water retention ability, a higher proton conductivity and a reduced swelling ratio, making it well suited for proton exchange membrane fuel cells (PEMFCs). Further, the composite membranes show improved mechanical properties at high temperature, thus ensuring the structural stability of membranes during the fuel cell operation. Compositional optimized AC-PEG/Nafion composite membrane (15 wt% compared to Nafion) demonstrates a better performance than the commercially available counterpart, Nafion 212, in fuel cell measurements. To identify the key factor of the improved performance, current interrupt technique is used to quantitatively verify the changes of resistance under different relative humidity environment. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Sulfonated graphene oxide/Nafion composite membranes for high-performance direct methanol fuel cells
(2013-10-17)
Chien, Hung-Chung
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Tsai, Li-Duan
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Huang, Chiu-Ping
;
Kang, Chi-yun
;
Lin, Jiunn-Nan
An easy and effective method for producing low methanol-crossover membranes is developed by dispersing sulfonated graphene oxide (SGO) into a Nafion matrix. A SGO/Nafion mixture with low SGO content exhibits unique viscosity behavior and allows for better SGO dispersion within the Nafion. After film casting, the composite membranes show lower methanol and water uptakes, a reduced swelling ratio, improved proton conductivity in low relative humidity, and extremely high methanol selectivity, which can be implemented in direct methanol fuel cells (DMFCs). The regular backbone of the composite membrane shows a higher storage modulus, increased a-relaxation (transition temperature), and improved tolerance to pressure during membrane electrode assembly (MEA). The small angle X-ray spectra indicate the shrinkage of the ionic clusters in the composite membranes, which thus reduce methanol crossover. The hybrid membranes applied to DMFCs demonstrate performances superior to that of the commercial Nafion 115 in 1 M and 5 M methanol solutions. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.