Methanol Fuel Cells with Anion-Exchange Membranes

Despite great efforts, this has not been achieved nntil now. Existing types of anion-exchange membranes (nsed for electrodialysis) are far inferior to Nafion both in their condnctivity and in chemical and thermal stability. Therefore, so far, one cannot meaningfnUy discnss the potential of these membranes as substitutes for the circulating or matrix electrolyte in alkaUne hydrogen-oxygen fuel cells. 

4 METHANOL FUEL CELLS WITH ANION-EXCHANGE 

The reactions occurring in methanol-oxygen fuel cells with alkaline electrolyte 

Anode CHsOH-hbOH Cathode 02 + 3H2O -I- 6e Overall CH3OH +102 

Yang et al. (2006) used a PVA/SSA membrane of their own make obtained by cross-linking of poly(vinyl alcohol) with 10 wt% sulfosuccinic acid. In a methanol-air fuel cell with such a membrane, they used 4 mg/cm Pt-Ru on carbon black as the anode catalyst and an inexpensive catalyst without platinum on the basis of Mn02 as the cathode catalyst. The electrolyte was 2 M KOH solution +2M CH3OH. At a temperamre of 30°C, the current density in the maximum-power point was about 10 mA/cm and the voltage was 0.245 V. At 60°C, the corresponding values were 15.4 mAJan and 0.268 V. 

---

Kim JH, Kim HK, Hwang KT, Lee JY (2010) Performance of air-breathing direct methanol fuel cell with anion-exchange membrane. Int J Hydrogen Energ 35 768-773... 

Bambagioni V, Bianchini C, Marchionni A, Filippi J, Vizza F, Teddy J, Serp P, Zhiani M (2009) Pd and Pt-Ru anode electrocatalysts supported on multi-walled carbon nanotubes and their use in passive and active direct methanol alcohol fuel cells with an anion-exchange membrane (alcohol = methanol, ethanol, glycerol). J Power Sources 190 241-251... 

Yu EH, Scott K (2005) Direct methanol alkaline fuel cell with catalysed anion exchange membrane electrodes. J Appl Electrochem 35 91-96... 

Although the focus of this article is on PEMs that are being used in automotive fuel cells today, brief mention must be made of work carried out on alkaline anion exchange membranes (AAEMs). Such membranes have the potential to exhibit sufficient activity when used with non-precious metal catalysts, may work with fuels such as methanol and ethylene glycol and provide some of the features that commercial PFSA membranes provide for PEMFCs. A cross-linked, water-insoluble. 

Yu and Scott prepared membrane assembly electrodes (MEAs) with Pt loadings in both anode and cathode CLs of about 2 mg cm for a direct methanol alkaline fuel cell using an anion exchange membrane. They found that the cell performance increased dramatically with an MEA that did not include the GDL on the anode, because of lower reactant mass transfer resistance [94]. They also used platinized Ti mesh as the anode and current collector in the AEMFC. The cathode was a standard gas diffusion electrode with a Pt loading of approximately 2 mg cm , which consisted of a backing layer (carbon paper), a GDL and a CL. The novel anode showed higher catalytie aetivity than the conventional Pt/C electrode, and gave stable fuel cell performance [95]. 

Bambagioni, V, Bianchini, C., Marchionni, A., et al. (1990). Pd and Pt-Ru Anode Electrocatalysts Supported on Multi-waUed Carbon Nanotubes and their Use in Passive and Active Direct Alcohol Fuel Cells with an Anion-exchange Membrane (Alcohol = Methanol, Ethanol, Glycerol), J. Power Sources, 190, pp. 241-251. 

Rao, A. H. N. Kim, H.-J. Nam, S. Kim, T.-H., Cardo poly(arylene ether sulfone) block copolymers with pendant imidazolium side chains as novel anion exchange membranes for direct methanol alkaline fuel cell. Polymer 2013, 54(26), 6918-6928. 

---