Polymer electrolyte membrane fuel cells (PEMFCs) have been studied intensively due to their great potential as a clean and efficient energy conversion device. Especially, considerable attention has been paid to the development of thin polymer electrolyte membranes (PEMs) for the practical application of PEMFCs. However, thin PEMs normally have poor physicochemical stability. It is well-known that the physicochemical stability of polymer membrane can be improved by cross-linking technology. In this presentation two different types of cross-linked membranes from sulfonated poly(arylene ether sulfone) (SPAES) will be introduced: 1) cross-linked SPAES membranes prepared using flexible perfluoropolyether as a cross-linker. 2) End group cross-linked SPAES membranes prepared via simple thiol-ene click reaction.

Anion exchange membrane fuel cells (AEMFCs) have been considered as a promising energy device. To make highly efficient AEMs, high ion conductivity, mechanical stabilities and alkaline stabilities are required. High ion conductivity generally accompanies poor mechanical properties, and crosslinking has been widely applied to overcome these problems. Our groups introduced novel terminally-crosslinked piperidinium-functionalized poly(arylene ether sulfone)s as a anion exchange membrane. Unlike the typical AEMs, our terminally-crosslinked membranes are expected to have high conductivity, especially at low RH conditions due to enhanced water-holding capacity, while maintaining the high chemophyscial stabilities by crosslinking. The synthesis, and properties of the prepared membranes will be discussed in detail.

Chlor-alkali (CA) membrane process is a commercially useful process to produce valued chemicals such as chlorine, sodium hydroxide and hydrogen via salined water electrolysis using sodium ion (Na+)-selective membranes. The most important issue in CA process is to reduce high energy consumption. A plausible solution is to obtain highly Na+-conductive membranes. The representative membrane materials are chemically stable perfluorinated sulfonic acid (PFSA) ionomers such as Nafion® and Aciplex®. PFSA membranes, but it is necessary to develop alternatives to PFSA membranes. In this study, a sulfonated poly(arylene ether sulfone) copolymer membrane is radiation-grafted with a highly sulfonated poly(styrene) used as a side chain material.

Sulfonated poly(arylene ether sulfone) (SPAES) random copolymers have been perceived as alternatives to perfluorinated sulfonic acid (PFSA) ionomers owing to their cheap production cost and low hydrogen permeability. In spite of their advantages, there are some issues to overcome such as membrane durability and relatively low proton conductivity in the low humidity range. An approach to solve these problems is to fill SPAES copolymers into porous support films (e.g., poly(tetra fluoro ethylene), PTFE). However, it is difficult to make defect-free pore-filling membranes. In this study, SPAES nanodispersion in a water-alcohol mixture is made under a modified supercritical condition and used to make highly proton conductive and chemical durable SPAES-PTFE pore-filling membranes.

본 연구에서는 고분자 전해질 연료전지(PEFC)의 전해질막의 화학적 안정성의 향상을 위하여 3-mercaptopropyl silica gel (3MPTSG)과 poly(arylene ether sulfone)(SPAES)을 이용하여 복합막을 제조하였다. 일반적으로 방향족 탄화수소계 고분자막은 전극 부분에서 발생한 라디컬에 의한 고분자 산화가 일어나 내구성이 감소하게 되는데 이는 대부분 주쇄에 포함 된 에테르 기 부분의 취약성으로 발생한다. 본 연구에서는 이러한 라디칼에 의한 고분자 주쇄의 산화를 방지하기 위해 친수 성의 무기물 입자를 도입하여 이온전도도 감소율을 최소화하고 산화안정성을 높이고자 하였다. 복합막들의 물성 및 전기화학 적 특성을 평가하기 위해 접촉각, FT-IR, 이온전도도, 이온교환용량(IEC), 함수율, 열안정성 등을 수행하였다. 실리카의 함량 이 0에서 0.5%까지 증가함에 따라 이온전도도 및 함수율은 각각 10% 감소한 0.076 S cm-1 및 16% 감소한 24.6 wt%이었으 나, 산화안정성은 10% 향상되었다.

Salined water electrolysis is one of representative commercial processes to produce valued chemicals such as chlorine, hydrogen. The most important issue in the electrolysis is to reduce energy consumption. A plausible solution is to accelerate Na+ion transport through cation exchange membranes and to reduce interfacial resistance with electrodes. The conventional membrane materials are based on PFSAs such as Nafion®. In spite of their robust chemical resistance, there are several critical demerits including expensive production cost and difficult tuning capability. For this, a SPAES random copolymer-silica nanocomposite is used as a membrane matrix with a high ionic conductivity and radiation-grafted with a highly sulfonated poly(strylene) to provide a branched polymer architecture for improved interfacial characteristics.

Sulfonated poly(arylene ether sulfone) copolymers are prepared by an aromatic substitution polymerization reaction as polymer electrolyte membranes for polymer electrolyte membrane fuel cells (PEMFCs). Thin, ductile films are fabricated by the solution casting method, which resulted in membranes with a thickness of approximately 50μm. The synthesized copolymers and membranes are characterized by 1H NMR, FT-IR, TGA, ion exchange capacity, water uptake and proton conductivity measurements. The prepared membranes are tested in a 9 cm2 commercial single cell at 80 ℃ and 120 ℃ in humidified H2/air under different relative humidity conditions. The prepared membrane is found to perform better than the commercial Nafion 112 membrane at 120℃ under low humidity condition.

리튬이온 이차전지는 리튬이온이 이동하면서 전기화학적 충방전사이클을 완성하는 에너지변환장치를 의미한다. 리튬이온 이차전지는 높은 에너지밀도와 낮은 자가방전률, 상대적으로 긴 수명주기 등 다양한 장점을 갖는다. 최근 전기차 수 요증가는 고용량 리튬이온 이차전지 개발을 촉진하고 있으나 음극에서의 dendrite 형성으로 인한 전기적 단락 현상과 전지 폭 발 문제와 같은 심각한 안전문제를 야기한다. 또한, 리튬이온 이차전지 구동시 상승된 온도에서 폴리올레핀계열(예 : 폴리에 틸렌과 폴리프로필렌) 격리막의 열수축 문제가 발생한다. 이와 같이 낮은 열 안정성은 리튬이온 이차전지의 성능과 수명의 감소로 이어진다. 본 연구에서는 폴리올레핀계열 함침격리막 제조를 위한 중요한 소재로서 술폰화 폴리아릴렌에테르술폰 랜 덤 공중합체를 사용하였으며, 제조된 격리막을 이용하여 dendrite 형성과 관련된 금속이온 흡착 능력과 리튬이온전도성, 열적 내구성이 평가되었다.

AEMFCs have been realized as a desirable alternative to PEMFCs. AEMs are the most important components of AEMFCs, and the high ion conductivity, good dimensional, mechanical and alkaline stabilities are required for AEMs. High conductivity mostly leads to a poor dimensional and mechanical stabilities. Chemical cross-linking of polymers have been attempted in an effort to overcome these problems, but the cross-linking inevitably reduced the conductivity due to the increased hydrophobicity of the membrane. Our group developed terminal crosslinking in which cross-linking was restricted only to the terminus of the polymer chains to minimize the loss of conductivity. Synthesis and properties of these terminally-crosslinked membranes will be detailed.

술폰화 폴리아릴렌에테르술폰(SPAES) 랜덤 공중합체는 고분자 전해질 연료전지에 적용될 때 높은 수소이온전도 도, 상대적으로 낮은 생산 단가 그리고 열화학적 저항성등과 같은 장점을 갖는다. 반면, SPAES 공중합체는 가혹한 구동 조건 하에서 낮은 화학적 안정성과 치수 불안전성으로 인해 실제 연료전지 막에 직접적으로 적용하는데 어려움이 있다. 그에 타당 한 해결책은 SPAES 공중합체를 상호 연결된 기공 구조와 높은 열화학적 강도를 가지는 지지체 필름(예 : 전기방사된 폴리이 미드 지지체)에 함침시키는 것이다. 본 연구에서는 함침막 제조를 위한 이오노머로 빠른 이온 수송을 위해 높은 자유 체적을 유도하는 회전 그룹을 갖는 SPAES 공중합체를 선택하였다. 제작된 막의 실용가능성은 막 특성화를 통해 평가되었다.

Sulfonated poly(arylene ether sulfone)(SPAES) random copolymers are representative alternatives to perfluorinated sulfonic acid(PFSA) ionomers used as the state-of-the-art polymer electrolyte membranes for fuel cells. SPAES copolymers have advantages such as low hydrogen permeability, low production cost. However, it is difficult to demonstrate high electrochemical single cell performances for a long period time, since SPAES membranes have critical interfacial issues with catalyst layers containing PFSA ionomers, particularly in the repeated hydrated and dehydrated cycles. In this study, called as radiation grafting of proton conductive polymers on SPAES membranes, is tried in order to improve proton conductivity without a severe loss in dimensional stability and to reduce interfacial resistance with PFSA catalyst layers at the same time.

Sulfonated poly(arylene ether sulfone) (SPAES) random copolymers have been perceived as alternatives to perfluorinated sulfonic acid ionomers used as polymer electrolyte membranes for fuel cells. SPAES copolymers are suffering from degradation under harsh fuel cell operation conditions. One solution to overcome the decomposition issue is to fill SPAES copolymers into polymeric support films (e.g., poly(tetrafluoro ethylene), PTFE) with interconnected porous structures. It is difficult to fill the SPAES copolymers dissolved in polar aprotic solvents into PTFE support films owing to their different surface energies. In this study, a SPAES nanodispersion in a water-alcohol mixture is used to make defect-free pore-filling membranes where poly(ethylene glycol) oligomers are added to induce advanced morphologies for fast proton conduction.

Sulfonated poly(arylene ether sulfone) (SPAES) random copolymers have been perceived as membrane materials alternative to perfluorinated sulfonic acid (PFSA) ionomers, since they are cheap and chemically tunable when compared with PFSA. Moreover, their relatively low gas permeability, particularly to hydrogen, contributes to reduced thermal decomposition of membrane-electrode assemblies. In spite of their advantages, freestanding SPAES copolymers have critical issues associated with chemical/electrochemical durability as well as interfacial resistance with electrodes. In this study, SPAES-PTFE reinforced membranes are fabricated using consecutive membrane formation protocols, (e.g., SPAES nanodispersion in water-alcohol mixtures, spontaneous pore-filling, and solvent-assisted thermal treatment techniques) and systematically evaluated.