• Korean Chemical Engineering Research
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• 제52권6호
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• pp.695-700
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• 2014

고분자전해질 연료전지로 물을 전기분해하여 수소와 산소를 발생시킬 수 있다. 그러나 1.7V 이상의 높은 전압에서 수전해 반응이 일어나므로 전극과 고분자 전해질 막의 열화가 빠르게 진행된다. 수전해 과정에서 anode의 열화를 방지하기 위해 촉매로 지지체 없는 $IrO_2$를 보통 사용하는데 본 연구에서는 고분자전해질 연료전지용 Pt/C 촉매를 수전해 반응에 그대로 사용했을 때 전극과 막의 열화 현상을 분석하였다. 1.8~2.0 V 전압 범위에서 수전해 반응 후 고분자 전해질 연료전지 구동 조건에서 I-V, CV, 임피던스, LSV를 측정했다. 수전해 전압이 높을수록 전극과 막의 열화 속도가 증가하였다. 2.0 V에서 1분 동안 수전해 반응했을 때 수소 수율은 88%였고, 전극과 고분자 막이 열화되어 0.6 V에서 성능이 49% 감소하였다.

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.1-5
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• 2021

PEM(Proton Exchange Membrane) 수전해는 PEM 연료전지와 동일한 PEM 전해질 막을 사용하며, 동일한 반응이지만 방향이 반대인 반응에 의해 진행된다. PEM 연료전지는 전해질 막과 촉매의 열화와 내구성에 대해 많은 연구가 진행되어 개발된 열화분석 방법이 많다. 본 연구에서 PEM 수전해 내구성 평가에 PEM 연료전지 내구성 평가 방법 적용이 가능한지 검토하였다. PEM 수전해 열화과정에서 PEM 연료전지와 동일한 조건으로 LSV(Linear sweep voltammetry), CV(Cyclic voltammetry), Impedance, SEM(Scanning Electron Microscope), FT-IR(Fourier Transform Infrared spectroscopy) 등을 분석해 비교하였다. PEM 연료전지처럼 막을 통과한 수소가 Pt/C 전극에서 산화되어 수소투과전류밀도를 측정함으로써 PEM 수전해 고분자 막의 열화정도를 분석할 수 있었다. 수소/질소 유입 조건에서 CV에 의한 전극활성면적(ECSA)을 측정해 전극열화를 분석할 수 있었다. 수소와 공기를 Pt/C 전극과 IrO2 전극에 공급하면서 각 전극의 임피던스를 측정해 전극과 고분자 막의 내구성을 평가할 수 있었다.

• 한국수소및신에너지학회논문집
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• 제28권1호
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• pp.17-23
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• 2017

Polyether ether ketone (PEEK) composite including tungstophosphoric acid(TPA) membranes have been intensively investigated for polymer electrolyte membrane water electrolysis (PEMWE) and thus covalently linked sulfonated polyether ether ketone (CL-SPEEK) with captured TPA composite membranes were prepared and characterized. Sulfonated polyether ether ketone (SPEEK) was prepared in sulfonation of PEEK and was cross-linked with 1,4 diiodobutane. The carbonyl group of SPEEK was reduced with $NaBH_4$ and 3-isocyanatepropyltriethoxysilane (ICPTES) was added. The TPA captured composite was prepared in reaction of TPA with 3-mercaptopropyltrime thoxysilane (MPTMS). The polymer composite membranes showed better thermostability and electrochemical properties than SPEEK. The membranes were prepared by sol-gel casting method. The polymer composite membrane featured 0.1285 S/cm of proton conductivity at $80^{\circ}C$ and outstanding durability.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.478-484
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• 2016

Polyether ether ketone (PEEK) composite membranes have been intensively investigated for polymer electrolyte membrane water electrolysis (PEMWE). Covalently linked (CL) sulfonated polyether ether ketone (SPEEK) and cellulose polymer composite membranes were prepared and characterized. Polyether ether ketone (PEEK) and cellulose were sulfonated and then were covalently linked by 1,4-diiodobutane to produce covalently linked SPEEK and cellulose polymer composite membranes. The composite membranes showed better thermostability and electrochemical properties than SPEEK. The membranes were prepared by sol-gel casting method. CL-SPEEK/Cellulose composite membrane featured 0.2453 S/cm of proton conductivity at $80^{\circ}C$ which was better than that of Nafion.

• Korean Chemical Engineering Research
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• 제55권4호
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• pp.478-482
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• 2017

고분자 전해질 연료전지의 구동과정 중 습도제어는 매우 중요한 제어 조건이다. 물 관리 측면에서는 저가습 조건이 유리하고, 배출수 활용 및 에너지 효율면에서는 고가습이 유리하다. 본 연구에서는 배출수 활용면에서 저가습과 고가습 구동 과정에서 배출수의 특성에 대해서 연구하였다. 배출수의 불순물은 막과 전극의 열화 과정에서 발생하는 것이므로 저가습과 고가습 조건에서 막전극합체(MEA)열화에 대해서도 연구하였다. 연료극 0% RH의 저가습 조건에서 라디칼 발생속도가 커 고분자 막 열화의 주요 원인임을 보였다. 양쪽 극 모두 고가습(RH 100%) 0.6 V에서 불소 이온 농도 약 20 ppb로 낮은 농도를 나타내서, 수전해 원료수로 사용하기에 충분하였다. 고가습 조건에서 배출한 응축수에서 0.2 ppb 이하의 매우 낮은 농도의 백금이 검출되었다.

• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.391-398
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• 2007

The covalently cross-linked sulfonated polyetheretherketone (CL-SPEEK) membrane was prepared by four-step synthesis of sulfonation-sulfochlorination, partial reduction, lithiation, and cross-linking, and its electrochemical and mechanical properties were investigated for water electrolysis application. The prepared ion exchange membranes showed good electrochemical and mechanical properties; proton conductivity of 0.116 S/cm at $80^{\circ}C$, water uptake of 44.6%, ion exchange capacity of 1.75 meq/g-dry-memb., tensile strength of 64.25 MPa and elongation of 61.11%. The membrane electrode assembly (MEA) with homemade membranes were prepared by non-equilibrium impregnation-reduction (I-R) method. Especially, the electrochemical surface area (ESA) and roughness factor of CL-SPEEK electrolyte by cyclic voltammetry method were 23.46 $m^2/g$ and 307.3 $cm^2-Pt/cm^2$, respectively. The prepared MEA was used in the unit cell of water electrolysis and the cell voltage was 1.81 V at 1 A/$cm^2$ and $80^{\circ}C$, with platinum loadings of 1.31 mg/$cm^2$.

• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.411-418
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• 2018

The polymer electrolyte membranes, CL-SPEEK/Cellulose composite membrane I, II, III with the improved electrochemical and mechanical properties were prepared and characterized. The engineering plastic polyether ether ketone (PEEK) and cellulose were sulfonated and cross-linked. The membranes were prepared by sol-gel casting method with different amount of cross-linking reagent. In conclusion, the composite membranes I, II, III showed improved thermostability, tensile strength and oxidative durability. Proton conductivity of the membranes was also improved and the composite membrane I showed 0.1312 S/cm at $80^{\circ}C$ which was the best of those composite membranes.

• 한국수소및신에너지학회논문집
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• 제28권4호
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• pp.338-344
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• 2017

Polyoxometal molybdophosphoric acid (MoPA) bonded polyether ether ketone (PEEK) composite membrane for water electrolysis has been investigated. The composited membrane, covalently cross linked (CL) sulfonated polyether ether ketone (SPEEK) with a bonded MoPA, was prepared in sulfonation of PEEK, cross linkage reaction with 1,4-diiodobutane, and addition with MoPA. PEEK was covalently cross-linked with 1,4-diiodobutane to improve mechanical strength and was added with MoPA to increase proton conductivity. MoPA should be fixed to back bone of SPEEK to prevent bleeding out. Therefore, the carbonyl group of SPEEK was reduced with NaBH4 and 3-isocyanatepropyltriethoxysilane (ICPTES) was added. The MoPA bonded composite was produced in the reaction of MoPA with 3-mercaptopropyltrimethoxvsilane (MPTMS). In conclusion, MoPA bonded CL-SPEEK composite membrane featured 0.129 S/cm of proton conductivity at $80^{\circ}C$, and 2,156 hours of chemical stability in Fenton test. These properties are better than those of membranes of other SPEEK system.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.151-160
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• 2014

CL-SPEEK/Cs-TPA/$CeO_2$ composite membrane was prepared for polymer electrolyte membrane water electrolysis (PEMWE). In order to improve the electrochemical, mechanical, durabilities and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated and the organic-inorganic blend composite membranes was prepared by loading cesium-substituted tungstophosphoric acid (Cs-TPA) by titration method with cross-linking agent contents of 0.01mL. Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the PEMWE circumstance and to increase the duration of the membrane. CL-SPEEK/$Cs_{(1)}$-TPA/CeriaIn conclusion, 1% membrane showed the optimum results such as 0.119 S/cm at $80^{\circ}C$ of proton conductivity and 62MPa of tensile strength.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.103-110
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• 2005

Proton conducting solid polymer electrolyte (SPE) membranes have been used in many energy technological applications such as water electolysis, fuel cells, redox-flow battery, and other electrochemical devices. The availability of stable membranes with good electrochemical characteristics as proton conductivity at high temperatures above 80 $^{\circ}C$ and low cost are very important for its applications. However, the presently available perfluorinated ionomers are not applicable because of high manufacturing cost and high temperature use to the decrease in the proton conductivity and mechanical strength. In order to make up for the weak points, the block copolymer (BPSf) of polysulfone and poly (phenylene sulfide sulfone) were synthesized and sulfonated. The electrolyte membranes were prepared with phosphotungstic acid (HPA)/sulfonated BPSf via solution blending. This study would be desirable to investigate the interaction between the HPA and sulfonated polysulfone. The results showed that the characteristics of SPSf/HPA blend membrane was a better than Nafion at high temperature, 100 $^{\circ}C$. These membranes proved to have a high proton conductivity, $6.29{\times}10-2$ S/cm, a water content, 23.9%, and a ion exchange capacity, 1.97 meq./g dry membrane. Moreover, some of the membranes kept their high thermal and mechanical stability.