Nanoporous separator and low fuel concentration to minimize crossover in direct methanol laminar flow fuel cells |
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Authors: | A.S. Hollinger R.J. Maloney R.S. Jayashree D. Natarajan L.J. Markoski P.J.A. Kenis |
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Affiliation: | 1. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 Green Street, Urbana, IL 61801, USA;2. Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Matthews Avenue, Urbana, IL 61801, USA;3. INI Power Systems, 175 Southport Drive, Suite 100, Morrisville, NC 27560, USA |
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Abstract: | Laminar flow fuel cells (LFFCs) overcome some key issues – most notably fuel crossover and water management – that typically hamper conventional polymer electrolyte-based fuel cells. Here we report two methods to further minimize fuel crossover in LFFCs: (i) reducing the cross-sectional area between the fuel and electrolyte streams, and (ii) reducing the driving force of fuel crossover, i.e. the fuel concentration gradient. First, we integrated a nanoporous tracketch separator at the interface of the fuel and electrolyte streams in a single-channel LFFC to dramatically reduce the cross-sectional area across which methanol can diffuse. Maximum power densities of 48 and 70 mW cm?2 were obtained without and with a separator, respectively, when using 1 M methanol. This simple design improvement reduces losses at the cathode leading to better performance and enables thinner cells, which is attractive in portable applications. Second, we demonstrated a multichannel cell that utilizes low methanol concentrations (<300 mM) to reduce the driving force for methanol diffusion to the cathode. Using 125 mM methanol as the fuel, a maximum power density of 90 mW cm?2 was obtained. This multichannel cell further simplifies the LFFC design (one stream only) and its operation, thereby extending its potential for commercial application. |
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