Development of sulfonated poly(phenylene oxide) and sulfonated silica hybrid composite membrane for vanadium redox flow battery system

( Sadhasivam Thangarasu ),정호영 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

The organic-inorganic hybrid composite membrane of sulfonated poly (phenylene oxide) (sPPO)-nano sized sulfonated silica (sSiO2) was prepared to improve the ionic conductivity (IC) and decrease vanadium permeability for vanadium redox flow battery (VRFB). Comparatively, the sPPO with 2% sSiO2 showed higher WU, IC and IEC than sPPO alone. The IC of hybrid membranes are 0.050, 0.073, 0.077 and 0.073 S/cm for sPPO, sPPO-1, 2 and 4% sSiO2 membranes, respectively. The hybrid membranes has exhibited higher IC because of hydrophilic properties of SiO2-SO3H in sPPO polymer matrix. The VO2+ perme-ability of Nafion®212, sPPO and sPPO- 2% sSiO2 hybrid membranes are 2.22 × 10-7, 2.50 × 10-8 and 4.76 × 10-9 cm2 min-1, respec-tively. The inorganic nanofillers of sSiO2 in sPPO membrane appeared to act as a barrier to VO2+ ions crossover. Low cost, high IC and lower vanadium permeability of sPPO-sSiO2 hybrid membrane can be considered as a promising ion exchange membrane for advanced VRFB system.

Sulfonated poly(phenylene oxide)/graphene oxide composite membrane for vanadium redox flow battery

( Sadhasivam Thangarasu ),정호영,임민화,문건오,박미정,노현준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Hybrid composite membrane of sulfonated poly(phenylene oxide) (sPPO) and graphene oxide were prepared for advanced vanadium redox flow battery system. Initially, the sulfonation functional group (-SO3H) was introduced in PPO polymer and then the various concentration of graphene oxide (GO) was mixed with sPPO polymer matrix. The inorganic properties of layered structured graphene oxide (GO) was introduced in sPPO polymer matrix for improve the mechanical stability and prevent the vanadium ion crossover. During VRFB unit cell operation, the GO act as barrier for vanadium ion permeability in membrane. Functional group and structural analysis of as prepared materials were confirmed by FTIR, XRD and TEM. Fundamental membrane properties of hybrid membrane were determined through the Degree of sulfonation, water uptake, swelling ratio, ion exchange capacity and ionic conductivity.

Electrochemical studies of sulfonated sillica supported Pt electrocatalyst for unitized regenerative fuel cells

( Sadhasivam Thangarasu ),임민화,문건오,박미정,노현준,이정명,정호영 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

The Platinum (Pt) nanoparticles were dispersed on the surface of sulfonated silica (SiO2-SO3H) and used as a bifunctional oxygen electrode for the unitized regenerative fuel cell (URFC) system. The electrochemical (ORR) performance of the Pt/SiO2-SO3H and Pt/SiO2 electrocatalysts are 800 mA cm(-2) and 600 mA cm(-2), respectively, at 0.70 V in the FC mode. The electrocatalytic performance of Pt/SiO2-SO3H is 30% higher than the Pt/SiO2 catalyst. In the WE mode, both the sulfonated and non-sulfonated SiO2/Pt electrocatalysts exhibited stable performance. The improved performance of the Pt/SiO2-SO3H catalyst is probably due to the sulfonic acid functional group in the silica support material. Therefore, this work confirms that the silica-supported sulfonation process used in this study is more effective for the improvement of the URFC performance.

Organic-inorganic hybrid composite membrane for Vanadium Redox Flow Battery Applications

( Sadhasivam Thangarasu ),정호영,임민화,문건오,박미정,노현준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Sulfonated poly (phenylene oxide) - nano sized silica (SiO₂) hybrid composite membrane was prepared for enhance the unit cell performance of vanadium redox flow battery application. Compared to other hydrocarbon polymers, the low cost of PPO were sulfonated through the chlorosulfonic acid (CSA). The inorganic SiO₂ nano particles were dispersed in the polymer matrix through the facile chemical synthetic techniques. Fourier transform infrared spectroscopy FTIR, x-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis were characterized for functional group and structural analysis. The physicochemical characterization of degree of sulfonation (DS), water uptake, swelling ratio, ion exchange capacity (IEC) and ionic conductivity (IC) were measured to the sPPO and hybrid membranes. Compared to various concentration of organic-inorganic materials, the composition of sPPO/1% SiO₂ membrane shows the excellent performances in the physico-chemical characterizations.

Electro-analytical performance of bifunctional electrocatalyst materials in unitized regenerative fuel cell system

Sadhasivam, T.,Palanisamy, Gowthami,Roh, Sung-Hee,Kurkuri, Mahaveer D.,Kim, Sang Chai,Jung, Ho-Young Elsevier 2018 International journal of hydrogen energy Vol.43 No.39

<P><B>Abstract</B></P> <P>The unitized regenerative fuel cell (URFC) is a round-trip energy conversion device for efficient energy storage systems that offers promising electrochemical energy conversion and environmentally friendly features. The electrocatalyst is a key component for operating URFC unit cell devices. Optimal electrocatalyst materials should be bi-functional with catalytic activity for the oxygen reduction and oxygen evolution reactions (ORR and OER). Over the past few decades, platinum has been recognized as a promising bi-functional electrocatalyst material for the URFC system. However, the ORR and OER activity of Pt is inadequate during the round-trip energy conversion process due to the formation of an oxide layer (PtO<SUB>x</SUB>) and the high onset potential for H<SUB>2</SUB> evolution. To address these issues, extensive effort has been made to enhance the OER performance without affecting the ORR performance. The most efficient alternative electrocatalyst materials comprise combinations of platinum group metals (PGMs) and their oxides, especially PtIr, PtIrRu, PtIrO<SUB>2</SUB>, PtIrIrO<SUB>2</SUB>, and PtIrO<SUB>2</SUB> RuO<SUB>2</SUB>. This comprehensive review emphasizes the potential of various bifunctional electrocatalyst materials for renewable energy generation in the URFC system. Herein, we discuss the limitations of Pt electrocatalysts in the URFC-OER process based on the reaction mechanism. The classification of different bifunctional electrocatalysts is extensively reviewed and highlighted based on the structural, microstructural, fuel cell-ORR, and water electrolysis-OER characteristics, round-trip energy conversion efficiency, inadequacies, and advantages. Taking these features into account, we discuss the possibilities and performance of cost-effective bifunctional electrocatalyst materials for the ORR/OER electro-catalytic process in advanced URFC systems. This review presents an exclusive vision for the development of bifunctional electrocatalyst materials and should stimulate research on bifunctional electrode-based URFC systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> URFC is an efficient round-trip energy conversion device with high specific energy. </LI> <LI> Bifunctional electrocatalyst is a key component for operating URFC unit cell. </LI> <LI> Pt suffered by formation of PtO<SUB>x</SUB> layer and high onset potential for H<SUB>2</SUB> evolution. </LI> <LI> Pt/IrO<SUB>2</SUB> is superior electrocatalyst material for efficient ORR/OER performances. </LI> <LI> Cost-effective and novel structured electrocatalysts are an alternative to PGM. </LI> </UL> </P>

A comprehensive review on unitized regenerative fuel cells: Crucial challenges and developments

Sadhasivam, T.,Dhanabalan, K.,Roh, Sung-Hee,Kim, Tae-Ho,Park, Kyung-Won,Jung, Seunghun,Kurkuri, Mahaveer D.,Jung, Ho-Young Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.7

<P><B>Abstract</B></P> <P>From extensive reported analyses, we reviewed the limitations, challenges, and advanced developments of the materials and components mainly used in the unitized regenerative fuel cell (URFC) system. URFC is a viable energy storage system owing to its high specific packaged and theoretical energy densities of 400–1000 Wh/kg and 3660 Wh/kg, respectively. Nevertheless, during the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), the stability and durability of the URFC unit cell was severely affected by various degradation factors in the stacked cell. The certain issues are related to the (i) electrocatalysts (high cost, aggregation, migration, and supportive material corrosion), (ii) dissolution and cracks in the Nafion binder, (iii) physical degradation and higher cost of polymer membrane, and severe carbon corrosion in (iv) gas diffusion packing and (v) bipolar plates. Among these factors, the critical challenges are the severe carbon corrosion and durability of the membrane in the unit cell regions. The degradation occurs in the supporting material of the electrocatalyst, gas diffusion packing, and bipolar plate owing to carbon corrosion because of the high applied potential in the water electrolyzer mode. Recent developments are significantly enhancing the durability and overcoming the limitations in the URFC system. In this comprehensive review, we have pointed out the limitations, challenges, and critical developments in URFC systems. Furthermore, built on our experimental and intellectual awareness in the context of URFC system developments, new strategies have been suggested to prepare novel structured materials and composites for advanced URFC applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> URFC is an optimum fuel cell system owing to its specific high energy density. </LI> <LI> Critical problem is severe carbon corrosion in electrocatalyst support and GDB, BP. </LI> <LI> Major challenges are cost and durability of the membrane and electrode assembly. </LI> <LI> Highly crystalline of Gr-carbon can be considered as a corrosion-resistant material. </LI> <LI> Novel structured and low cost materials are most promising to advanced URFC system. </LI> </UL> </P>

Graphitized carbon as an efficient mesoporous layer for unitized regenerative fuel cells

Sadhasivam, T.,Roh, S.H.,Kim, T.H.,Park, K.W.,Jung, H.Y. Pergamon Press ; Elsevier Science Ltd 2016 International journal of hydrogen energy Vol.41 No.40

<P>To enhance the electrochemical performance of membrane electrode assemblies (MEAs) for unitized regenerative fuel cells (URFCs), we prepared and introduced graphitized-carbon (Gr-carbon) of high crystallinity as a mesoporous layer (MPL) in MEAs. The round-trip energy conversion efficiencies (epsilon(RT) (%)) of non-MPL, typical amorphous-carbon (Am carbon) MPL and Gr-carbon MPL containing MEAs at the current density of 1 A cm(-2) were 36.6, 41.8, and 43.8, respectively. The overall round trip energy efficiency was considerably higher for the graphitized form of mesoporous carbon. For Gr-carbon, a high stability of the round-trip energy conversion efficiency was achieved even after 20th cycles (42.3%) owing to the enhanced electrical conductivity and high crystallinity of Gr-carbon after thermal treatment. Therefore, Gr-carbon considerably enhances the ORR and OER performances and prevents carbon corrosion and surface oxidation during the fuel cell and water electrolyzer modes in the URFC system. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</P>

Preparation and characterization of Pb nanoparticles on mesoporous carbon nanostructure for advanced lead-acid battery applications

Sadhasivam, T.,Dhanabalan, K.,Roh, S. H.,Kim, S. C.,Jeon, D.,Jin, J. E.,Shim, J.,Jung, H. Y. Springer Science + Business Media 2017 Journal of materials science Materials in electron Vol.28 No.7

<P>To enhance the electrochemical energy performance, the lead nanoparticles on mesoporous carbon (Pb on MPC) were prepared and characterized for advanced lead acid battery (Ad-LAB) applications. At present, Ad-LAB garners significant attention in energy storage devices because of its high charge acceptance. However, the major problem has associated with the large crystallization of PbSO4 in negative electrode during unit cell operation. To minimize this issue, Pb nanoparticles have incorporated on MPC in this present investigation. The Pb on MPC has prepared through facile chemical reduction process. The structural analysis of Pb, MPC, and Pb on MPC have confirmed by X-ray diffraction analysis. The specific surface area (SSA) and pore size distribution of MPC and Pb on MPC has obtained through Brunauer-Emmett-Teller measurements. The obtained SSA is 245.38 and 32.42 m(2) g(-1) for MPC and Pb on MPC, respectively. Additionally, the incorporation of Pb on MPC has confirmed by the microstructural analysis of high resolution transmission electron microscopy. The obtained particle sizes of the Pb nanoparticles are similar to 5 nm. Based on the structural, microstructural and cyclic voltammetry analysis, we suggest that Pb on MPC can be used as an efficient active material for negative electrode in Ad-LAB systems.</P>

Thermal and Electrochemical characteristics of naturally mixed rare earth metal oxides with graphene oxide nanocomposite

( Sadhasivam Thangarasu ),임민화,문건오,박미정,노현준,이정명,정호영 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

This study elucidates the preparation of Mischmetal oxide (Mm-oxide) - graphene oxide (GO) nanocomposite for thermal and electrochemical properties. In nanocomposite, the Mm-oxide has supportive in improving the thermal stability of GO. Decreasing the decomposition temperatures of GO occurs by broken sp(2) system in earlier temperature. This result indicates that the Mm-oxide could improve the thermal stability and the decomposition reaction kinetics of GO. The determined non-isothermal activation energies are 137.61 and 107.25 kJ/mol for GO and GO-Mm-oxide composite, respectively. The current density is effectively increased for composite (1.741×10(-5)A) compared to GO (1.341×10(-5)A) and Mm-oxide (1.719×10(-5)A). It indicates that the nanocomposite materials have larger peak current. Therefore, the cost effective nanocomposite can be considered as a promising materials for electrochemical energy applications.

Low permeable composite membrane based on sulfonated poly(phenylene oxide) (sPPO) and silica for vanadium redox flow battery

Sadhasivam, T.,Kim, Hee-Tak,Park, Won-Shik,Lim, Hankwon,Ryi, Shin-Kun,Roh, Sung-Hee,Jung, Ho-Young Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.30

<P><B>Abstract</B></P> <P>The proton conductivity and vanadium permeability of organic-inorganic (sulfonated poly (phenylene oxide) (sPPO)-nano sized sulfonated silica (sSiO<SUB>2</SUB>)) hybrid membrane were investigated for application in a vanadium redox flow battery (VRFB) system. Significant attention is being paid to PPO polymers as a replacement for Nafion<SUP>®</SUP> membranes due to their relatively low cost and ease of sulfonation. The attachment of a sulfonic acid (SO<SUB>3</SUB>H) functional group to PPO and SiO<SUB>2</SUB> was confirmed using Fourier Transform Infrared Spectroscopy (FTIR). The hybrid membrane (sPPO-2% sSiO<SUB>2</SUB>) exhibited increased thermal stability, water uptake (WU), ion exchange capacity (IEC) and proton conductivity (IC) compared with a conventional organic sPPO membrane. The proton conductivity of the hybrid membrane increased considerably compared to sPPO alone, resulting from the 2% sSiO<SUB>2</SUB> nanoparticles added homogeneously to the polymer matrix. The proton conductivities of the sPPO and hybrid membranes were 0.050 and 0.077 S/cm, respectively. The increased proton conductivity of the hybrid membrane was attributed to the enhanced hydrophilic properties of SO<SUB>3</SUB>H in the membranes. In addition, inorganic particles in the polymer matrix acted as a barrier for vanadium ion crossover. During VRFB unit cell operation, vanadium ion (VO<SUP>2+</SUP>) crossovers were measured as 14.66, 1.955 and 0.173 mmol L<SUP>−1</SUP> through Nafion<SUP>®</SUP>212, sPPO and hybrid membranes, respectively, and VO<SUP>2+</SUP> permeability were 2.22 × 10<SUP>−7</SUP>, 2.50 × 10<SUP>−8</SUP> and 4.76 × 10<SUP>−9</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP> for Nafion<SUP>®</SUP>212, sPPO and hybrid membranes, respectively. Based on our experimental results, low cost organic-inorganic hybrid membranes as prepared provide an efficient alternative membrane material for advanced VRFB systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel Organic-Inorganic hybrid structured membrane for advanced VRFB system. </LI> <LI> PPO as a replacement for Nafion<SUP>®</SUP> membranes due to low cost and ease of sulfonation. </LI> <LI> Proton conductivity increased to hybrid membrane (0.077 S/cm) compared to sPPO alone. </LI> <LI> VO<SUP>2+</SUP> permeability of sPPO-sSiO<SUB>2</SUB> membrane is significantly lower than Nafion<SUP>®</SUP>212. </LI> <LI> sSiO<SUB>2</SUB> in the sPPO polymer matrix acted as a barrier for vanadium ion crossover. </LI> </UL> </P>