Performance comparison of portable direct methanol fuel cell mini-stacks based on a low-cost fluorine-free polymer electrolyte and Nafion membrane

A low-cost fluorine-free proton conducting polymer electrolyte was investigated for application in direct methanol fuel cell (DMFC) mini-stacks. The membrane consisted of a sulfonated polystyrene grafted onto a polyethylene backbone. DMFC operating conditions specifically addressing portable applica...

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Bibliographic Details
Published in:Electrochimica acta 2010-08, Vol.55 (20), p.6022-6027
Main Authors: Baglio, V., Stassi, A., Modica, E., Antonucci, V., Aricò, A.S., Caracino, P., Ballabio, O., Colombo, M., Kopnin, E.
Format: Article
Language:English
Subjects:
Accumulators
Applied sciences
Backbone
Collectors
Direct methanol fuel cells
Electrolytes
Energy
Energy. Thermal use of fuels
Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc
Exact sciences and technology
Fluorine-free membrane
Fuel cells
Membranes
Methyl alcohol
Mini-stack
Passive mode
Portability
Proton exchange membrane
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Summary:A low-cost fluorine-free proton conducting polymer electrolyte was investigated for application in direct methanol fuel cell (DMFC) mini-stacks. The membrane consisted of a sulfonated polystyrene grafted onto a polyethylene backbone. DMFC operating conditions specifically addressing portable applications, i.e. passive mode, air breathing, high methanol concentration, room temperature, were selected. The device consisted of a passive DMFC monopolar three-cell stack. Two designs for flow-fields/current collectors based on open-flow or grid-like geometry were investigated. An optimization of the mini-stack structure was necessary to improve utilization of the fluorine-free membrane. Titanium-grid current collectors with proper mechanical stiffness allowed a significant increase of the performance by reducing contact resistance even in the case of significant swelling. A single cell maximum power density of about 18 mW cm −2 was achieved with the fluorine-free membrane at room temperature under passive mode. As a comparison, the performance obtained with Nafion 117 membrane and Ti grids was 31 mW cm −2. Despite the lower performance, the fluorine-free membrane showed good characteristics for application in portable DMFCs especially with regard to the perspectives of significant cost reduction.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2010.05.059