Selectivity of Direct Methanol Fuel Cell Membranes

Abstract

Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion® were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate–PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion® 115-based MEA (77 mW·cm−2 vs. 64 mW·cm−2). This result was due to a lower methanol crossover (47 mA·cm−2 equivalent current density for s-PEEK vs. 120 mA·cm−2 for Nafion® 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm2 for s-PEEK vs. 0.22 Ohm cm2 for Nafion® 115).

Ruthenium–Platinum Catalysts and Direct Methanol Fuel Cells (DMFC): A Review of Theoretical and Experimental Breakthroughs

“…Though not analyzed here in detail, one should also remark recent studies aiming to improve Ru-Pt catalysts by consideration of carbon based material as supports [48][49][50][51][52] or improving the membrane selectivity [53]. These carbon-supported catalysts are synthesized through different techniques leading to different nanoparticles sizes and Ru-Pt alloying grades which affects the reactivity [54,55].…”

Performance analysis of Fe–N–C catalyst for DMFC cathodes: Effect of water saturation in the cathodic catalyst layer

“…Thus, a higher flooding effect is predicted at higher methanol concentration. A higher flooding effect is also expected considering the higher amount of crossovered methanol at higher methanol concentration at the anode side [97,98]. Fig.…”

New Materials and Flow Field Design for Middle‐Temperature Direct Methanol Fuel Cell with Low Cathode Pressure

“…Arico et al. studied selectivity towards methanol permeation of several sulfonic acid‐functionalized polymer electrolyte membranes based on hydrocarbon systems, such as blend sulfonated polyether‐etherketone (s‐PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate–PFSA polymers. Among investigated membranes in 2M methanol and within 60–90 °C temperature range, s‐PEEK ones showed best cell performance principally due to lower equivalent methanol cross‐over current (48 and 74 mA cm −2 vs .…”