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Recently, the interest in high-performance energy storage system (ESS) is increasing since it is a very essential part of the smart grid for stable and efficient electricity supply. At present, diverse battery technologies such as lithium ion batteries, redox flow batteries (RFBs), and sodium–sulfur batteries are competing with each other to be applied to commercial ESS. Among them, RFBs are considered to be the most promising for a large-scale ESS application. Meanwhile, all-vanadium redox flow batteries (VRBs) utilizing vanadium ions in different oxidation states as the active redox species have been considered as one of the most promising RFBs owing to the controlled crossover rate of the redox species through membranes. Since an ionomer membrane separator is one of the most dominant components determining the charge-discharge characteristics of RFB systems, the development of highly efficient membranes has been considered to be very essential for successful commercialization of VRBs. Among various kinds of membranes, pore-filled ion-exchange membranes (PFIEMs) fabricated by combining a porous substrate and an ionomer are known to have excellent characteristics including high chemical and dimensional stabilities, low manufacturing cost, low mass transfer resistance, etc. In this work, we have developed novel PFIEMs by using a polyethylene (PE)- or a polytetrafluoroethylene (PTFE)-based porous substrate for VRB applications. Especially, we have designed the filling ionomer to possess the high crosslinking degree and ion-exchange capacity, simultaneously. In addition, the prepared PFIEMs and the RFB employing them have been systematically analyzed by various electrochemical methods for evaluating their performances exactly. The detailed results will be presented and discussed at the conference. This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology funded by Korea Ministry of Environment.

Ion exchange membranes (IEMs) have been widely employed in various water treatment processes such as electrodialysis for a desalination of sea or brackish water. Recently, they have also gained increased industrial importance in the applications to electrochemical energy conversion and storage processes such as reverse electrodialysis, fuel cells, and redox flow batteries. Their intrinsic properties such as electrical resistance and permselectivity are the key parameters dominating the electrochemical energy conversion efficiencies. The cost-effectiveness of ion-exchange membranes should also be considered for successful commercialization of the IEM process. In recent years, pore-filled IEMs (PFIEMs) in which an inert porous substrate provides excellent mechanical and chemical stabilities while a filling ionomer selectively transports ions through the membrane have been receiving great interests in the application to various separation and energy processes. In this work, we have investigated the optimum design parameters of the cost-effective PFIEMs for successful application to various IEM processes. In more detail, novel PFIEMs were successfully fabricated by combining a highly porous polymer (i.e. PTFE and PE) films and cationic polyelectrolytes with structurally stable anion-exchange sites for the applications to alkaline direct liquid fuel cells, all vanadium redox flow battery, and reverse electrodialysis. The prepared PFIEMs exhibited excellent electrochemical characteristics and stabilities and also remarkable energy conversion efficiencies have been achieved by employing them. Acknowledgments: This work was supported in part by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20153030031720) and the Technology Innovation Program funded by the Korea government (MOTIE) (No. 10047796).

There has been much attention towards dye-sensitized solar cells (DSSCs) for the past decades due to their attractive features such as high energy conversion efficiency and low production cost etc. Recently, cobalt complexes have been suggested as one of the most promising candidates for replacing conventional iodine redox couples owing to their high voltage characteristics. Even though respectable energy efficiency exceeding 12% was reported by employing liquid electrolyte that consists of cobalt complex redox mediator and volatile solvent, the use of volatile liquid solvent cannot ensure the long-term stability of DSSCs. In this work, therefore, novel polymer gel electrolytes (PGEs) including cobalt complexes as redox couples have been prepared for efficient and long-term stable DSSCs. In addition, several ways to mitigate the charge recombination rate at the interface between PGE and photoanode have been systematically investigated. The electron transport properties in mesoporous TiO2 electrodes (i.e. electron lifetime and diffusion coefficients) have been evaluated through IMPS and IMVS analyses. In addition, the photovoltaic performances of DSSCs employing prepared PGEs have been evaluated via the J-V curve measurements and various electrochemical characterizations. Acknowledgments: This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology (KEITI) funded by Korea Ministry of Environment (MOE).

Polymer gel electrolytes (PGEs) have been widely investigated and utilized in various electrochemical applications such as lithium secondary batteries and dye-sensitized solar cells because they possess moderate ion conductivity and high physical stability. They have also been developed for the application to electrochromic devices (ECDs). Recently, ECDs have been attracting much attention owing to their use as a smart window. A smart window or a smart glass can effectively control the light transmission properties for the purpose of proper lighting or heating etc. The PGEs as one of the key components of the ECDs can dominate the major characteristics of transmittance and colored time etc. Especially, the ion conductivity and volatility of the PGEs should be optimized for the fabrication of efficient and durable ECDs. In addition, efficient injection process of highly viscous PGEs during the fabrication of large area ECDs should also be considered. In this work, therefore, we have developed the PGEs which can be easily loaded as a film and then in-situ polymerized through UV irradiation. The PGEs have also been applied to photoelectrochemical cells (i.e. dye-sensitized solar cells) for the efficient energy harvesting from solar irradiation. Acknowledgments: This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology (KEITI) funded by Korea Ministry of Environment (MOE).