Nanoporous separator and low fuel concentration to minimize crossover in direct methanol laminar flow fuel cells

✍ Scribed by A.S. Hollinger; R.J. Maloney; R.S. Jayashree; D. Natarajan; L.J. Markoski; P.J.A. Kenis

• Book ID: 104025963
• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 903 KB
• Volume: 195
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2009.12.063

✦ Synopsis

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.