title: A semi-interpenetrating network approach for dimensionally stabilizing highly-charged anion exchange membranes for alkaline fuel cells.
abstract: There is a delicate balance between ion exchange capacity (IEC), conductivity, and dimensional stability in anion exchange membranes as higher charge content can lead to increased water uptake, causing excessive swelling and charge dilution. Using highly-charged benzyltrimethylammonium polysulfone (IEC=2.99 mEq g(-1) ) as a benchmark (which ruptured in water even at room temperature), we report the ability to dramatically decrease water uptake using a semi-interpenetrating network wherein we reinforced the linear polyelectrolyte with a crosslinked poly(styrene-co-divinylbenzene) network. These membranes show enhanced dimensional stability as a result of lower water uptake (75 % vs. 301 % at 25 °C) while maintaining excellent hydroxide conductivity (up to 50 mS cm(-1) at 25 °C). These improvements produced an enhanced alkaline fuel cell capable of generating 236 mW cm(-2) peak power density at 80 °C. This method is easily adaptable and can be a viable strategy for stabilizing existing systems.
authors.affiliation: Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA 94305 (USA). stevehe@stanford.edu, curt.frank@stanford.edu.
authors.forename: Steve S
authors.initials: SS
authors.lastname: He
authors.forename: Alaina L
authors.initials: AL
authors.lastname: Strickler
authors.forename: Curtis W
authors.initials: CW
authors.lastname: Frank
mesh_terms: D004553:Electric Conductivity; D011211:Electric Power Supplies; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D007474:Ion Exchange; D007700:Kinetics; D055595:Mechanical Phenomena; D008567:Membranes, Artificial; D011108:Polymers / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D013450:Sulfones / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D008567:Membranes, Artificial; D011108:Polymers; D011137:Polystyrenes; D013450:Sulfones; D014867:Water; C017662:polysulfone P 1700; C003771:Amberlite XAD-2 resin; C031356:hydroxide ion
keywords: fuel cells; interpenetrating network; ion exchange; membrane; polyelectrolyte