• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.144-149
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• 2005

Sulfonated poly(ether ether ketone) (SPEEK) was blended with poly(ether sulfone) (PES) at various compositions. To investigate the possibility of using the blend membranes as polymer electrolyte membranes for direct methanol fuel cell, the blend membranes were characterized in terms of methanol permeability, proton conductivity, ion exchange capacity, and water content. Both proton conductivity and methanol permeability of SPEEK were relatively high. As the amount of PES increased, methanol permeability decreased more rapidly compared to proton conductivity. The experimental results indicated that the blend membrane with 40 wt% PES was the best choice in terms of the ratio of proton conductivity to methanol permeability.

• Membrane Journal
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• v.33 no.6
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• pp.325-343
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• 2023

Direct methanol fuel cells (DMFCs) have been attracting attention as energy conversion devices that can directly supply methanol liquid fuel without a fuel reforming process. The commercial polymer electrolyte membranes (PEMs) currently applied to DMFC are perfluorosulfonic acid ionomer-based PEMs, which exhibit high proton conductivity and physicochemical stability during the operation. However, problems such as high methanol permeability and environmental pollutants generated during decomposition require the development of PEMs for DMFCs using novel ionomers. Recently, studies have been reported to develop PEMs using hydrocarbon-based ionomers that exhibit low fuel permeability and high physicochemical stability. This review introduces the following studies on hydrocarbon-based PEMs for DMFC applications: 1) synthesis of grafting copolymers that exhibit distinct hydrophilic/hydrophobic phase-separated structure to improve both proton conductivity and methanol selectivity, 2) introduction of cross-linked structure during PEM fabrication to reduce the methanol permeability and improve dimensional stability, and 3) incorporation of organic/inorganic composites or reinforcing substrates to develop reinforced composite membranes showing improved PEM performances and durability.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.492-501
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• 2017

A 900 W scale direct methanol fuel cell (DMFC) stack is designed and fabricated for unmanned aerial vehicle (UAV) applications. To meet the volume and weight requirements, metallic bipolar plates are applied to the DMFC stack for the first time wherein POS470FC was chosen as bipolar plate material. To ensure good robustness of the metallic bipolar plate based DMFC stack, finite element method based simulations are conducted using a commercial ANSYS Fluent software. The stress buildup and deformation characteristics on bipolar plates and end plates are analyzed in details. The present DMFC stack exhibits the performance of 1,130 W at 32 V and 35.3 A, clearly demonstrating that it could successfully operate for UAVs requiring around 1,000 W of power.

• Korean Membrane Journal
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• v.5 no.1
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• pp.18-24
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• 2003

In order to improve the mechanical properties of the sulfonated polysulfone (SPSf) membranes previously synthesized in our laboratory, poly(vinyl alcohol) (PVA) was blended which is well known as the excellent physical and chemical properties. The resulting membranes blended with several molecular weight of PVA varying from 13,000 to 124,000 have been characterized to investigate the effect of PVA molecular weight in terms of ion conductivities, methanol permeabilities, water contents and ion exchange capacities for both heat treated and untreated membranes at 150$^{\circ}C$. The proton conductivity is decreased as the molecular weight of PVA increases. The plain SPSf-6.0 showed the proton conductivity of 0.078 S/cm whereas the blended membrane with M.W. 31,000 PVA indicated 0.04 S/cm. For methanol permeabilities, when PVA is added to SPAf-6.0, methanol crossover is increased because of the gain of the hydrophilicity from 3.4 to 6.5${\times}$10$\^$-6/ $\textrm{cm}^2$/s. For the annealed blended membranes (with M.W. 31,000 PVA), both the methanol corssover and proton conductivity showed very consistent values, about 2.3${\times}$10$\^$-6/ $\textrm{cm}^2$/s and 0.036 S/cm, respectively.

• Clean Technology
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• v.13 no.4
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• pp.293-299
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• 2007

Direct coating of catalyst layer on the $Nafion^{(R)}$ membrane has been optimized in the process of fabrication of membrane electrode assembly (MEA) to enhance the performance of direct methanol fuel cell (DMFC). In this method, the contact resistance at the interface of the catalyst layer and the membrane was found to be low. The effect of catalyst loading, thickness of membrane and the gas diffusion layer (GDL) with or without the presence of micro-porous layer (MPL) on the performance of the MEA was also investigated. The MEA fabricated by the above-mentioned method exhibited a performance of $147\;mW/cm^2$ and $100\;mW/cm^2$ at $80^{\circ}C$ and $60^{\circ}C$, respectively, with the catalysts loading of $4\;mg/cm^2$.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.123-127
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• 2016

Methanol fuel cells having advantages of relatively favorable reaction kinetics and higher energy density have attracted increasing interests as best alternative to hydrogen fuel cell because of H2 production, storage and distribution issues. While there have been extensive research works on developing key components such as electrocatalysts as well as their physicochemical properties in practical formic acid fuel cells, there have also been urgent requests for investigating which fuel sources will be more suitable for direct liquid fuel cells in future. In this mini-review, we highlight the overall interest and outlook of formic acid fuel cells in terms of electrocatalysts, fuel supply and crossover, water management, fuel cell efficiency and system integration in comparison with methanol fuel cells.

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.161-164
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• 2002

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.193-196
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• 2002

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.201-202
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• 2002

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.15-18
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• 2002