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.

염수전기분해(saline water electrolysis) 또는 클로로-알칼리 막공정(chlor-alkali membrane process)은 양이온교환 막과 전극으로 구성되는 전해셀에 전기를 가하여, 고순도(> 99%)의 고부가가치 화합물(예 : 염소, 수소, 수산화나트륨)을 직 접 제조하는 화학공정이다. 염수전기분해의 경제성은 동일한 양의 화합물을 생산하기 위해 투여되는 에너지 소비량을 저감 시킴으로 달성될 수 있다. 이러한 이슈는 전해질이나 전극의 고유 저항을 줄이거나, 전해질과 전극 사이의 계면 저항을 감소 시킴으로 달성시킬 수 있다. 본 연구에서는 전자빔 동시조사법을 사용하여, 높은 화학적 안정성을 지닌 탄화수소계 술폰산 이 오노머 막의 표면에 높은 이온선택성을 갖는 고분자를 접목 시키는 시도가 이루어졌다. 이를 통해, 고분자 전해질 막의 이온 전도성을 보완함과 동시에, 전극과의 계면 저항을 감소시켜, 전기화학적 효율 향상이 이루어짐을 관찰하였다.

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.

Lithium ion battery are one of representative rechargeable batteries with high energy density, tiny memory effect, and low self-discharge and composed of anode, cathode, electrolyte, and membrane separator. The importance of membrane separator has been improved further as electric vehicle market increases rapidly. The conventional membrane separators are based on polyolefin (e.g., polyethylene and/or polypropylene). In case of lithium ion battery with a high capacity, polyolefin membrane separators are suffering from low thermal resistance and easy short-circuit formation leading to overheating. For these reasons, in this study, gel polymers are in-situ synthesized in electrolytes used as solvent, which are located in pores of polyolefin separators to obtain gel polymer electrolyte-polyolefin reinforced membranes.

A key element of environmentally friendly electric vehicles (EVs) based on polymer electrolyte fuel cells (PEFCs) and lithium ion batteries (LIBs) is an ion-selective membrane, which can transport specific ions such as proton and lithium ions, and provide mechanical and chemical resistances. The state-of-the art membranes for PEFCs and LIBs are perfluorinated sulfonic acid ionomer reinforced membranes and ceramic-coated polyolefin separators, respectively. In spite of the improvement of membranes characteristics, additional membrane modifications are still needed to improve electrochemical cell performances and to extend their lifetime. In this presentation, several plausible approaches to improve membrane characteristics are introduced.

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.