R2R Fabrication of Pore-Filling Cation-Exchange Membranes via One-Time Impregnation and Their Application in Reverse Electrodialysis

Abstract

Pore-filling ion-exchange membranes have been produced via complex, low energy efficient, and toxic processes, including repetitive impregnation to fully fill the porous substrates with polymer electrolytes, and using polar organic solvents and acids/bases for optional postmodifications. In the present work, we analyzed the characteristics of a pore-filling cationexchange membrane (PCEM) fully filled with a photocured electrolyte polymer in the pores of the substrate via repetitive impregnation. On the basis of these characteristics and in order to fabricate a PCEM via one-step impregnation, an aqueous photocurable solution with a high concentration of anionic monomeric electrolytes was developed via the simultaneous use of two types of anionic monomeric electrolytes. A fully filled PCEM with a width of 62 cm and a thickness of 16 μm was successfully fabricated using this aqueous photocurable solution via single impregnation in a roll-to-roll (R2R) process at a process speed of 1 m/min. The characteristics of this PCEM were almost the same as those of a handmade PCEM. In addition, the power density of a reverse electrodialysis stack consisting of the fabricated PCEMs with low resistance was higher than that of a stack consisting of commercial membranes. Based on these results, we confirmed that PCEM can be prepared at an industrial scale via a simple, energy-efficient, and environmentally friendly R2R process using an aqueous photocurable solution with a high concentration of anionic monomeric electrolytes.

Correlations between Properties of Pore-Filling Ion Exchange Membranes and Performance of a Reverse Electrodialysis Stack for High Power Density

“…On the other hand, the challenging issue of IEM development is also related to the evaluation of IEM performance in the commercial (large size) RED stack. However, thus far, evaluations of RED-specific IEMs were generally performed using a laboratory-scale (small size) RED stack [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ] because mass production of high-performance IEMs for RED stacks without an optimized roll-to-roll (R2R) process has been quite difficult [ 24 , 25 ]. Therefore, the evaluation and validation of large RED stacks is limited to the use of commercial IEMs [ 8 , 26 , 27 , 28 , 29 , 30 ]; furthermore, there are few studies on the correlation between IEM characteristics and large-scale RED performance although this is a critical factor in designing the strategy for upscaling RED.…”

“…In the recent years, several studies were conducted to develop pore-filling ion exchange membranes (PIEMs) for high-performance RED stacks with high power density and/or high energy efficiency [ 13 , 24 , 25 , 31 , 32 , 33 ]. The PIEMs fabricated in our laboratory have low electrical resistance because of a thin porous substrate and conductive electrolyte in its nanopores.…”

Ion Exchange Membrane for Reverse Electrodialysis

“…Yang S, et al [26] incorporated ion exchangeable materials into the porous membrane. This is a roll-to-roll (R2R) porefilling process consisting of pretreatment, impregnation, photopolymerization, and polishing.…”

“…The pore-filled CEM (PCEM) showed IEC of 1.839 meq/g, AR of 0.475 Ω cm 2 , and permselectivity of 96%. Also, the pore-filled AEM (PAEM) exhibited IEC of 1.645 meq/g1, AR of 0.661 Ω cm 2 , and permselectivity of 94.3% [26,27]. Gao H, et al [9] engineered the surface of AEMs via layer-by-layer (LBL) method with negatively charged poly(styrenesulfonate) (PSS) and positively charged poly(ethyleneimine) (PEI) polyelectrolytes.…”

Pore-Filled Anion-Exchange Membranes with Double Cross-Linking Structure for Fuel Cells and Redox Flow Batteries

“…Among the various kinds of IEMs, pore-filled IEMs (PFIEMs), which are composed of a thin and mechanically strong porous substrate film, and polyelectrolyte that fills the pores, are known to provide both the high ion conductivity and mechanical strength [36][37][38][39]. They could also be fabricated by a simple and cheap manufacturing process [39]. Recently, we have developed novel pore-filled AEMs (PFAEMs) for application to electrochemical energy conversion systems [11].…”