The influence of electrode morphology on the performance of a DMFC anode
2002 (English)In: Journal of Applied Electrochemistry, ISSN 0021-891X, E-ISSN 1572-8838, Vol. 32, no 3, 259-265 p.Article in journal (Refereed) Published
For low concentrations of methanol, mass transfer in the electrode is a limiting parameter for the direct methanol fuel cell (DMFC). To improve mass transfer, it is possible to induce convection in the gas backing layer or even in the porous electrode. In this study electrodes with different amounts of PTFE were compared to observe the influence of morphology on the anode performance. The hypothesis was that adding PTFE to the anode may make the morphology more favourable for carbon dioxide to evolve as a gas by creating the necessary pore sizes. Electrode performance was characterized electrochemically and the anode layer structure was studied using SEM, Hg-porosimetry and the van der Pauw method for measuring electric conductivity. Pores smaller than 0.04 mum were unaffected by adding PTFE while the volume fraction of pores of 0.04-1.0 mum diameter increased. Electrodes with 50% PTFE also performed as nonhydrophobized, despite the much higher ohmic losses and thickness. This implies that, above a certain amount, adding PTFE has a positive effect and that optimizing the electrode with PTFE may give better performance than electrodes without PTFE. The results suggest that gas evolves within the electrode, giving improved mass transfer in the liquid phase.
Place, publisher, year, edition, pages
2002. Vol. 32, no 3, 259-265 p.
direct methanol fuel cell anode, DMFC, gas evolution, mass transfer, PTFE, gas-diffusion electrode, methanol fuel-cells, mass-transfer, reaction layer, carbon, evolution, microstructure, nucleation, thickness, bubbles
IdentifiersURN: urn:nbn:se:kth:diva-21563ISI: 000175764400003OAI: oai:DiVA.org:kth-21563DiVA: diva2:340261
QC 201005252010-08-102010-08-10Bibliographically approved