• 한국세라믹학회지
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• 제42권2호
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• pp.77-80
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• 2005

A series of proton conductive composite membranes based on poly(vinyl alcohol) and phosphosilicate gels powders were successfully prepared. The proton conductivity of these composite was attributed to the phosphosilicate gel, which derived from tetraethoxysilane and phosphoric acid by sol-gel process at a molar ratio of P/Si = 1.5. The proton conductivity increased with increasing both the content of phosphosilicate gel and relative humidity. Temperature dependence of conductivity showed a Vogel-Tamman-Fulcher type behavior, indicating that proton was transferred through a liquidlike phase formed in micropores of phosphosilicate gel. The high conductivity of 0.065 S/cm with a membrane containing 60 wt$\%$ of the gel was obtained at $60^{\circ}C$ at $90\%$ relative humidity.

• 한국세라믹학회지
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• 제51권4호
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• pp.248-259
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• 2014

Acceptor-doped cerium pyrophosphates have shown significant proton conductivity of > $10^{-2}Scm^{-1}$ in the range of $100-300^{\circ}C$ and are considered promising candidates for use as electrolytes in proton-conducting, ceramic electrolyte fuel cells (PCFCs). But, cerium pyrophosphates themselves do not have structural protons, and protons incorporate into their material bulk only as impurities on exposure to a hydrogen-containing atmosphere. However, proton incorporation and proton conduction in these materials are expected to be affected by factors such as the nature (ionic size and charge) and concentration of the aliovalent dopant, processing history (synthesis route and microstructure), and the presence of residual phosphorous phosphate ($P_mO_n$) phases. An exact understanding of these aspects has not yet been achieved, leading to large differences in the magnitude of proton conductivity of cerium pyrophosphates reported in various studies. Herein, we systematically address some of these aspects, and present an overview of factors affecting proton conductivity inacceptor-doped $CeP_2O_7$.

• Korean Membrane Journal
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• 제6권1호
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• pp.44-54
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• 2004

Organic-inorganic composite membranes based on sulfonated poly(phthalazinone ether sulfone) (sPPES)/silica hybrid were prepared using the sol-gel process under acidic conditions. The sulfonation of PPES with concentrated sulfuric acid as sulfonation agent was carried out to prepare proton exchange membrane material. The behaviors of the proton conductivity and methanol permeability are depended on the sulfonation time (5-100 hr). The hybrid membranes composed of highly sulfonated PPES (IEC value: 1.42 meq./g) and silica were fabricated from different silica content (5-20 wt%) in order to achieve desirable proton conductivity and methanol permeability demanded for fuel cell applications. The silica particles within membranes were used for the purpose of blocking excessive methanol cross-over and for forming the path way to transport of the proton due to absorbing water molecules with ≡SiOH on silica. The presence of silica particles in the organic polymer matrix results in hybrid membranes with reduced methanol permeability and improved proton conductivity.

• 공업화학
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• 제16권1호
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• pp.144-149
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• 2005

Poly(ether ether ketone)을 설폰화시킨 후 poly(ether sulfone) (PES)과 다양한 조성으로 혼합하여 블렌드 막을 제조하였고, 직접메탄올 연료전지(DMFC; Direct Methanol Fuel Cell)용 고분자 전해질 막으로의 응용 가능성을 살펴보기 위하여 조성의 변화에 따른 메탄올 투과도, 수소 이온 전도도, 이온 교환 용량, 그리고 함수율의 변화를 살펴보았다. Sulfonated poly(ether ether ketone) (SPEEK)의 경우 수소 이온 전도도는 비교적 우수하였으나 메탄올 투과도 역시 비교적 높았다. 그러나, PES의 양이 증가함에 따라 수소 이온 전도도보다 메탄올 투과도가 급격히 감소하여서 PES의 양이 40%일 때 가장 좋은 선택성을 나타내었다.

• 한국세라믹학회지
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• 제23권4호
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• pp.85-89
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• 1986

Electrical conductivity have been measured as function of temperature in MgO.$P_2O_5$ glasses containing small amounts of water. Conduction was due to the contribution of $H^+$ and the mobility of protons in the glass increased linearly with increasing its concentration. The conductivity was pro-portional to the square of the proton concentration and the activation energy decreased linerly with increasing logarithm of the proton concentration, And $$\sigma$_0$ and $A_0$ was independent of the proton concentration but not on glass compositions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.147-147
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• 2010

An electrolyte membranes for high temperature/low humidity is a demand for the proton exchange membrane fuel cells (PEMFCs). In this work, we prepared hybrid membranes, which have novel glass content in the hydrophilic and hydrophobic part of sulfonated poly(arylene ether sulfone) (SPAES) by in-situ sol-gel synthesis of various functional silane. The effect of silicate from functional silane content on the proton conductivity, water uptake of the hybrid membranes under high temperature and low humidity was quantitatively identified. The silicate content contributed to the enhancement of not only proton conductivity, but also water retention ability for PEMFCs operation.

• Korean Membrane Journal
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• 제6권1호
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• pp.1-9
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• 2004

The impedance and the subsequent proton conductivity of Nafion$\^$/ membranes as standard samples were measured and compared via the two-probe method and the four-probe method using the prepared impedance measurement system. The different impedance behavior for the same membrane was observed at the fully hydrated state in the Nyquist impedance plot. The effect of the humidity and the temperature on the proton conduction through a membrane was investigated and compared with two different cell configurations.

• 한국세라믹학회지
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• 제53권3호
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• pp.301-305
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• 2016

We investigate proton conduction in a nonstoichiometric ${\Sigma}3$ $BaZrO_3$ (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as -0.70 and -0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature.

• Macromolecular Research
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• 제11권6호
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• pp.458-466
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• 2003

Several copolyimides have been synthesized with different combinations of comonomers in order to study the relationship between conductivity and water insolubility. m-Phenylenediamine (m-PDA), an angled comonomer, was introduced into the polymer backbone to increase water absorption, and resulted in higher proton conductivity. 2,2-bis(trifluoromethyl)benzidine (TFMB) was used as the comonomer to promote water insolubility. There is a good correlation between the water uptake and conductivity of the polyimides. The copolyimides that had high water uptake also generated high proton conductivity. Those polyimides had good mechanical properties. The copolyimides that have 27 mol% of TFMB and 9 mol% of m-PDA have reasonable conductivities and are insoluble in water at 90$^{\circ}C$, even though they have lower conductivities than those of the homopolymer.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.241-247
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• 2005

A series of proton conductive inorganic-organic hybrid membranes doped with phosphoric acid ($H_3PO_4$) and/or triethylphosphate (PO(OEt)$_3$) have been prepared by sol-gel process with 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) as precursors. High proton conductivity of 3.0 ${\times}$ $10^{-3}$ S/cm with composition of 50TEOS-30GPTMS-20APTES-50$H_3PO_4$ was obtained at 120 ${^{\circ}C}$ under 50% relative humidity. Thermal stability of membrane was significantly enhanced by the presence of SiO$_2$ framework up to 250 ${^{\circ}C}$. XRD revealed that the gels are amorphous. IR spectra showed a good complexation of $H_3PO_4$ in the matrix. The conductivity under 75% relative humidity was significantly improved by addition of APTES due to the increase in concentration of defected site in hybrid matrix. The effect of PO(OEt)$_3$, humidifying time, and heat-treatment were also investigated. PO(OEt)$_3$ had no improvement on conductivity and conductivity increased with humidifying time, however, decreased with heating temperature.