A magnetic field-induced through-plane alignment of proton highway in proton exchange membrane

현종현,두기수,김희탁,육성민,이동현,이동욱,최선규,권지윤 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Proton exchange membranes with high proton conductivity in the through-plane direction are enormously required for fuel cells. However, isotropically distributed proton conducting channels of current membranes imposes a limitation. Herein, we present aligned proton conducting channel in membrane thickness direction, achieved by magnetic field-induced alignment of proton conductive magnetic tungsten disulfides nanowires in Nafion membrane. In contrast to a tortuous proton pathway in conventional Nafion membranes, the nanowire/Nafion composite membrane provides unidirectional pathway in thickness direction. Due to the unidirectional water channels enriched at the interface of the nanowire and Nafion, the composite membrane exhibits enhanced proton conductivity at low humidifications. The proton exchange membrane fuel cell employing the composite membrane shows significantly improved power performance.

A sulfonated poly(arylene ether sulfone)/polyimide nanofiber composite proton exchange membrane for microbial electrolysis cell application under the coexistence of diverse competitive cations and protons

Park, Sung-Gwan,Chae, Kyu-Jung,Lee, Mooseok Elsevier 2017 Journal of membrane science Vol.540 No.-

<P><B>Abstract</B></P> <P>A sulfonated poly(arylene ether sulfone) (SPAES)/polyimide nanofiber (PIN) composite proton exchange membrane was developed for use in microbial electrolysis cells (MECs), where diverse cations that compete with proton coexist in high concentrations. It was fabricated by impregnating SPAES as a proton-conducting polymer into PIN as a supporter for mechanical reinforcement. The membrane showed excellent mechanical and dimensional stability (tensile strength > 40MPa) due to membrane reinforcement by nanofibers, despite having a high water uptake (35 ± 3%) and ion exchange capacity (2.3 ± 0.3meq/g). This novel membrane was highly selective for protons while excluding other competing cations; thus, it significantly mitigated the proton accumulation problem in the anode when applied to actual MECs. In addition to 1.5-fold greater proton transport, the SPAES/PIN membrane exhibited 3–10-fold less undesirable crossover of other cations depending on the species and 2–2.5-fold less gas permeability compared to Nafion-211 membrane. The application of this membrane improved hydrogen production efficiency of MEC by 32.4% compared to Nafion-211 and better hydrogen purity (90.3% for SPAES/PIN vs. 61.8% for Nafion-211). Therefore, this novel membrane has good potential for MEC applications, especially when protons and other competing cations are present together, due to its superior proton selectivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hydrocarbon-based SPAES/PIN composite proton exchange membrane was developed. </LI> <LI> Sulfonated poly(arylene ether sulfone) (SPAES) was used as a proton conductor. </LI> <LI> The SPAES/PIN composite membrane showed excellent mechanical and dimensional stability. </LI> <LI> The novel membrane was highly selective for protons while excluding other competing cations. </LI> <LI> The membrane showed significant improvement over Nafion-211 for microbial electrolysis cell performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced proton conductivity of sulfonated poly(ether ether ketone) membranes at elevated temperature by incorporating (3-aminopropyl)triethoxysilane-grafted graphene oxide

Shuguo Qu,Chenchen Zhang,Minhui Li,Yan Zhang,Lunbo Chen,Yushuai Yang,Bo Kang,Yiwei Wang,Jihai Duan,Weiwen Wang 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.12

Making inexpensive proton exchange membrane with high proton conductivity for the proton exchange membrane fuel cell (PEMFC) is still a challenging problem. Graphene oxide (GO) nanoparticles grafted with (3-aminopropyl) triethoxy silane (APTES) were prepared and then incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix by solution casting to make the composite proton exchange membrane. The obtained nanoparticles and composite membranes were characterized by XRD, FT-IR, Raman, TGA, SEM, and UTM. GO treated with the silane coupling agent improved the dispersion stability and compatibility of GO in SPEEK, which decreased the agglomeration of GO nanoparticles in the SPEEK membrane. The prepared nanocomposite membranes exhibited better water retention properties and proton conductivity. The proton conductivity of the SPEEK membrane with 2wt% amine functionalized GO (AGO) reached 11.32mS/cm at 120oC, which was 2.45-times higher than that of the pristine SPEEK membrane. The reason was that AGO nanoparticles disperse uniformly in the SPEEK membranes, which provides new channels for proton transfer. The potential application of this composite membrane in the PEMFC was indicated.

A comparative study on the performance of highly conductive sulfonated poly(ether ether ketone) PEM modified by halloysite nanotubes, sulfonated polystyrene and phosphotungstic acid

Seyed Hesam-Aldin Samaei,Gholamreza Bakeri,Mohammad Soleimani Lashkenari 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2

Proton transfer is the most important task of proton exchange membranes (PEMs) for application in fuel cells. One vital disadvantage of currently used commercial Nafion membranes is the low proton conductivity at high temperatures. Therefore, the objective of this research was to increase the proton conductivity of PEMs based on sulfonated poly (ether ether ketone) (SPEEK). Herein, modification of SPEEK-based PEM was carried out using polydopamine- coated halloysite nanotubes (HNT) alone and in combination with sulfonated polystyrene (SPS) and phosphotungstic acid (PWA). In this method, poly (ether ether ketone) sulfonation process was performed under optimum operating conditions to create more sulfonic acid groups on its chains. Here, polydopamine was doped on the outer surface of HNT (DHNT) and employed as the additive to create additional proton transferring pathways in the membrane. The hydrophilicity of the modified nanotube was enhanced through silanization (named as DHNTS). Moreover, SPS and PWA were applied to improve the ability of protons to transfer through the proton barrier channels in the membrane. Performing the sulfonation of polystyrene in the solution phase was a novel approach in this study, which led to significant increase in the degree of sulfonation. The results showed that the SPEEK/DHNTS|SPS and SPEEK/DHNTS|PWA membranes in the presence of 15% weight ratio additives and 100% relative humidity exhibited 109% and 90% higher proton conductivity than the neat SPEEK membrane, respectively. Furthermore, 20% and 10% higher proton conductivity was observed for the aforementioned membranes compared to the commercial Nafion117 membrane. Because of the strong acid-base bonding between DHNTS and SPEEK and the sticky nature of polydopamine, the chemical stability of the modified PEMs was higher than the neat membrane. In terms of fuel cell performance, there was little difference between Nafion117 membrane and DHNTS-modified PEM. These modified membranes are therefore suitable alternatives to address the commercial Nafion membrane’s gap in the fuel cells.

Accelerated testing of polymer electrolyte membranes under open-circuit voltage conditions for durable proton exchange membrane fuel cells

Han, Myungseong,Shul, Yong-Gun,Lee, Hyejin,Shin, Dongwon,Bae, Byungchan Elsevier 2017 International journal of hydrogen energy Vol.42 No.52

<P><B>Abstract</B></P> <P>Nafion NRE212, Nafion HP, and a hydrocarbon-based membrane were used in an accelerated open-circuit voltage (OCV) test to examine their oxidative stability. The catalyst layer and the gas permeability were analyzed to apply the same experimental conditions for each electrolyte membrane. The accelerated OCV test was conducted for ∼800 h, and the states of the membrane electrode assembly (MEA) were investigated by measuring the electrolyte membrane resistance, cyclic voltammograms, and linear sweep voltammograms with respect to time. Typically, the sulfonated poly(arylene ether), which has a low oxidative stability, showed the best performance in the OCV test, followed by the Nafion HP membrane and Nafion NRE212 membrane. The inherent oxidative durability of the electrolyte membrane and the gas permeability likely play a crucial role in the oxidative stability during MEA operation. The results further confirmed that the gas permeability affects the stability of the electrode in the catalyst layer.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We examined several membranes for use in proton exchange membrane fuel cells. </LI> <LI> We compared perfluorinated sulfonic acid and hydrocarbon electrolyte membranes. </LI> <LI> Accelerated open-circuit voltage tests determined their oxidative stability. </LI> <LI> We show that the gas permeability affects the stability of the electrode. </LI> </UL> </P>

Sulfonated graphene oxide (SATS-GO) composite membranes for proton exchange membrane fuel cells (PEMFCs) application

이현희,한주성,김은기,김정환,조경화,이종찬 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Sulfonated graphene oxide (SATS-GO) was incorporated into the sulfonated poly(arylene ether sulfone) as a filler to prepare composite membranes for polymer electrolyte membrane fuel cells (PEMFCs). Sulfonated graphene oxide could be obtained by modification of graphene oxide (GO) using sulfonated poly(arylene thioether sulfone) (SATS). The SPAES/SATS-GO composite membranes were fabricated by casting the SPAES and SATS-GO solution mixtures using a doctor blade film applicator. To study the effect of SATS-GO, pristine GO composite membrane was also prepared as a control group. The SPAES composite membranes containing the SATS-GO showed improved chemical, mechanical properties and exhibited high proton conductivity compared to pristine SPAES membrane. At 80°C and 40% RH, SPAES/SATS-GO-2.0 composite membrane exhibited increased proton conductivity of 4.63 mS cm^-1.

Multilayer-structured, SiO₂/sulfonated poly(phenylsulfone) composite membranes for proton exchange membrane fuel cells

Lee, J.R.,Won, J.H.,Yoon, K.S.,Hong, Y.T.,Lee, S.Y. Pergamon Press ; Elsevier Science Ltd 2012 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.37 No.7

In an effort to improve the dimensional change and proton conductivity of sulfonated poly(phenylsulfone) (SPPSU) membranes and facilitate their application to proton exchange membrane fuel cells (PEMFC), we develop a new composite membrane featured with a multilayer structure. The multilayer structure consists of a SPPSU-impregnated SiO<SUB>2</SUB> ceramic layer and a SPPSU layer. In contrast to a bulk composite membrane containing randomly dispersed SiO<SUB>2</SUB> nanoparticles, this unusual multilayer-structured composite membrane has an independent ceramic layer comprising close-packed SiO<SUB>2</SUB> nanoparticles and polyetherimide (PEI) binders. On the basis of structural characterization of the composite membranes, the effects of the multilayer structure on the membrane properties are investigated. The introduction of the SiO<SUB>2</SUB> ceramic layer is found to be effective in not only suppressing dimensional change but also enhancing proton conductivity of the multilayered composite membrane. Another intriguing finding is that the decrease of proton conductivity at a low humidity condition encountered in conventional water-swollen membranes is retarded in the multilayered composite membrane. These improvements in the proton conductivity of the multilayered composite membrane are discussed by considering the morphological uniqueness and the water retention capability of hygroscopic SiO<SUB>2</SUB> nanoparticles.

Antioxidant proton conductive toughening agent for the hydrocarbon based proton exchange polymer membrane for enhanced cell performance and durability in fuel cell

Yang, Sungwoo,Kim, Dukjoon Elsevier 2018 Journal of Power Sources Vol.393 No.-

<P><B>Abstract</B></P> <P>The antioxidant toughening agent for the hydrocarbon based proton exchange polymer electrolyte membranes, cerium/organosiloxane polymer network (Ce/OSPN), is synthesized via sol-gel reaction. Ce/OSPN is introduced to the sulfonated poly(ether ether ketone) (SPEEK), a typical hydrocarbon type polymer electrolyte membrane, by formation of a semi-interpenetrating polymer network (semi-IPN) structure. As Ce/OSPN possesses superior properties to SPEEK in mechanical flexibility, proton conductivity, and oxidation stability than SPEEK, it resolves 3 inherent drawbacks of the pristine SPEEK membrane including (i) brittleness, (ii) low proton conductivity, and (iii) poor durability. Addition of 20 wt% Ce/OSPN (at Ce/silicon mol ratio = 0.10) enhances the elongation at break of the SPEEK membrane about twice. The power density of the MEA fabricated with the semi-IPN membrane is 208 mW cm<SUP>−2</SUP>, which is much higher than that of the pristine SPEEK membrane, 165 mW cm<SUP>−2</SUP>. The power density loss of the same semi-IPN membranes as determined by the Fenton's test is 4.8%, whereas those of pristine and semi-IPN membrane without cerium are 33.9% and 34.0%, respectively. This Ce/OSPN agent is expected to be applied to a variety of hydrocarbon based polymer electrolyte membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SPEEK65/Ce/OSPN proton exchange membrane was fabricated via sol-gel reaction. </LI> <LI> SPEEK65/Ce/OSPN showed higher conductivity than pristine SPEEK65 membrane. </LI> <LI> SPEEK65/Ce/OSPN showed even superior chemical stability to pristine SPEEK65. </LI> <LI> SPEEK65/Ce/OSPN showed higher peak power density than pristine SPEEK65. </LI> </UL> </P>

Composite membranes based on modified graphene oxide and polybenzimidazole showing improved physicochemical properties and high proton conductivity for high-temperature proton exchange membrane

김정환,김기현,한주성,이현희,김혜진,이종찬 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Polybenzimidazole (PBI) composite membranes based on modified graphene oxide (ImGO) containing benzimidazole group as a filler material were prepared for the application in high temperature proton exchange membrane fuel cell (HT-PEMFC). Since ImGO has benzimidazole group, same functional unit with PBI matrix, the compatibility of ImGO with PBI is enhanced. Thereby, PBI composite membrane having ImGO exhibited improved physicochemical properties, such as mechanical properties, oxidative and thermal stability. Especially, high proton conductivity compared with pristine PBI and PBI composite membrane having GO is observed. For example, proton conductivity of composite membrane having 0.5 wt.% of ImGO, at 150 °C under anhydrous condition, was 77.52 mS cm^-1 which is 46.9% larger than that of the pristine PBI membrane.

Preparation and characterization of sulfonated semi-crystalline poly(arylene ether)s containing 1,4-FBB moiety as proton exchange membrane fuel cells

Jeong, Jong-Eon,Kim, Dong-Hyeon,Lee, Dong-Hoon Elsevier 2018 International journal of hydrogen energy Vol.43 No.51

<P><B>Abstract</B></P> <P>Sulfonated semi-crystalline poly(arylene ether)s copolymers containing 1,4-bis(4-fluorobenzoyl)benzene (1,4-FBB), with different degrees of sulfonation (DS), were successfully synthesized via direct polycondensation of 3,3’-disulfonate-4,4’-difluorodiphenylsulfone, bisphenol A, and 1,4-bis(4-fluorobenzoyl)benzene, based on aromatic nucleophilic substitution. The different DS values were realized by controlling the quantity of the sulfonated monomer. The effects of DS on the thermal, mechanical, and oxidative stabilities, water uptake, and ion exchange capacity of the membranes were determined. Compared with Nafion 212<SUP>®</SUP>, a state-of-the-art proton-conducting membrane, the block copolymer membrane showed well-separated phase morphology and high proton conductivity at different temperatures. The chemical and phase-separated structures of the copolymers were characterized by proton nuclear magnetic resonance spectroscopy and atomic force microscopy studies. The results showed that semi-crystalline copolymer membranes had acceptable mechanical, thermal, electrochemical, and chemical stabilities. All the above-mentioned results indicate that these semi-crystalline copolymer membranes are good candidate materials for proton exchange membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SPAESKK membranes were developed and employed as PEMs in PEMFC applications. </LI> <LI> Membranes show comparable IECs, water uptake and high thermal stability. </LI> <LI> SPAESKK 50 showed better proton conductivity than Nafion 212<SUP>®</SUP>. </LI> <LI> Performance of SPAESKK 50 was superior to that of Nafion 212<SUP>®</SUP> at 80 °C under 100% RH. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>