A Direct Methanol Alkaline Fuel Cell Based on Poly(phenylene) Anion Exchange Membranes

Abstract

The Investigation of the performance of poly(phenylene) based anion exchange membranes (AEMs) in a direct methanol fuel cell is reported. The fuel cell performances were tested with different anode gas diffusion layers as a function of concentrations of fuel and electrolyte using two commercially available platinum catalysts supported on carbon. Normalized current density values demonstrated good performance for a poly(phenylene) AEM, with a cation consisting of six methylene spacers attached to a trimethyl ammonium group, with a maximum current density of 11.8 mA cm −2 mg −1 in a KOH free fuel. The platinum catalyst (46%) from Tanaka showed a better performance (10.4 mA cm −2 mg −1 ) compared to the platinum catalyst from E-TEK (5.1 mA cm −2 mg −1 ) in 1M methanol fuel feed under identical conditions. We observed that the MEA with a Zoltek gas diffusion layer on the anode showed the best performance (226 mA cm −2 and 53.8 mW cm −2 ) in the presence of KOH, suggesting that a hydrophilic gas diffusion layer plays a significant role in improving the fuel cell performance. A durability test for a MEA in 1M methanol and 1M KOH for 67 h showed an overall degradation rate of 400 μV h Direct methanol fuel cells based on proton exchange membranes (PEMs) have received considerable attention, as compared to hydrogen fuel cells, they have potential system simplicity, high system energy density, improved volumetric fuel storage and fuel supply. 1,2Direct methanol alkaline fuel cells (DMAFCs) which employ an anion exchange membrane (AEM) electrolyte are more attractive than devices based on PEMs as they should provide improved electrode kinetics, simple water management, lower methanol permeability, and use of non-platinum metal catalysts.3-6 Solid-state AEM electrolytes are more attractive than the conventional liquid KOH electrolytes as the carbonates and bicarbonates formed during operation do not precipitate as the cation is the AEM, and although adding an additional ionic resistance to the electrode, do diffuse through the cationic ionomer. 7,8 In spite of these advantages, it is important to note that except for a few reports, high performance in DMAFCs are shown only in the presence of the aqueous basic electrolyte, even for commercially available AEMs.9,10 In general, alkaline DMFC studies employ commercially available AEMs, such as Tokuyama A-006, A-010, Fumatech FAA-2, and Morgane ADP from Solvay. [9][10][11][12][13][14][15][16] Radiation grafted membranes have been demonstrated to be promising AEMs for DMAFCs with a KOH free methanol fuel.17,18 Still a great amount of research is being focused on improving the performance of available commercial AEMs as well as on development of new AEMs to achieve stable, highly conducting, and mechanically robust membranes for fuel cells with high performance and long durability.There are very few alkaline direct methanol fuel cell reports where neat methanol is used and aqueous methanol is still the fuel of choice, in fact high power densities have only been achieved for these ...

Quaternized poly(phenylene oxide) anion exchange membrane for alkaline direct methanol fuel cells in KOH‐free media

“…From Figure , it is concluded that the optimal amount of amine to be added was in the ratio of 1:8 with respect to CPPO. Janarthanan et al reported the ADMFC peak power density of 3.97 mW cm −2 in methanol with no hydroxide ion moiety in the fuel which is comparable with our present results.…”

“…PPO is one of the widely used thermoplastic for the preparation of ion exchange membranes because of its easy accessibility, good solubility, high chemical and thermal stability . Generally, PPO is used as a precursor for the preparation of various functional polymers by chemical modification either in their aryl or benzylic positions for its use as solid polymer electrolyte.…”

“…Generally, PPO is used as a precursor for the preparation of various functional polymers by chemical modification either in their aryl or benzylic positions for its use as solid polymer electrolyte. Janarthanan et al investigated the performance of poly(phenylene)‐based AEM in a DMFC with different anode gas diffusion layers using two commercially available platinum catalysts supported on carbon. Katzfuß et al developed an AEM from 1,5‐dimethylpolyphenylenoxide by using N‐bromosuccinimide as brominating reagent.…”

Durability and performance of polystyrene‐b‐poly(vinylbenzyl trimethylammonium) diblock copolymer and equivalent blend anion exchange membranes

“…Chemical degradation is a concern with AEMs as both the cation species and polymer backbone are susceptible to attack by hydroxide. For this reason, many AEM polymer chemistries are under investigation, including perfluorinated AEMs that resemble perfluorinated sulfonic acid (PFSAs), polysulfone and polyphenylene based AEMs, and precast films (FEP/ETFE) irradiated to generate cation functionalities grafted on the polymer . Various cation species, including quaternary phosphonium, tertiary sulfonium, and guanidinium based compounds, are being studied for alkali stability .…”

Direct Methanol Anion Exchange Membrane Fuel Cell with a Non-Platinum Group Metal Cathode based on Iron-Aminoantipyrine Catalyst

“…All fuel cells run with this technology to date that show higher power densities use added OHions in the fuel. The ultimate aim would be to run these direct methanol fuel cells without added KOH [9]. The reason for adding hydroxide is that stoichiometrically the oxidation of methanol requires 6 OHions, the hydroxide flushes the slow moving carbonate and bicarbonate, formed from reaction of CO2 and OH -, out of the anode and it improves the anode potential as > 300 mV reduction in anode over potential is possible [5].…”