PTFE-Based Solid Polymer Electrolyte Membrane for High-Temperature Fuel Cell Applications

Abstract

The demand for a solid polymer electrolyte membrane for fuel-cell systems, capable of withstanding temperatures above 130°C , has prompted this study. A low-cost, highly conductive, nanoporous proton-conducting membrane, based on a polytetrafluoroethylene (PTFE) backbone has been developed. It comprises a nonconductive nano-size ceramic powder, PTFE matrix, and an aqueous acid. Impregnation of the ceramic powder into the PTFE matrix was carried out using sol-gel synthesis. The preparation procedures were studied and the membrane was characterized. This membrane demonstrated promising properties of high thermal stability (up to 300°C ), pressure-retention difference up to 2.2bars , room-temperature conductivity up to 0.11Scm−1 (10–15% (w/w) SinormalO2 , 3M normalH2SnormalO4 ), a hydrophilic/hydrophobic pore ratio of 1:1 and very high water flow at low pressure. A nonoptimized direct-methanol fuel cell with a 137μm thick membrane was assembled and tested. It produced 133mWcm−2 at 80°C , 0.05bars (g) dry air, 1.9 stoich (air), and 198mWcm−2 at 110°C , 2.2bars (g) dry air, 1.9 stoich (air).

High temperature (HT) polymer electrolyte membrane fuel cells (PEMFC) – A review

“…Higher operating temperatures mean that water management is simplified significantly as there is only a single (gaseous) phase present. This means that the transport of water in the membrane, electrodes and diffusion layer is easier and flow field plate design can be greatly simplified [10,11,13]. Another effect of the higher temperatures is that the reactant and product gases are expected to have increased diffusion rates [9] and with no liquid water present to block the electrochemically active surface area thus allowing for more reactions to occur.…”

Application of a Coated Film Catalyst Layer Model to a High Temperature Polymer Electrolyte Membrane Fuel Cell with Low Catalyst Loading Produced by Reactive Spray Deposition Technology

“…Three of the most significant challenges facing the wide commercialization of proton exchange membrane fuel cells (PEMFCs) are: (1) improving catalyst tolerance to impurities [1][2][3][4][5][6]; (2) simplifying water and thermal management schemes [1][2][3][4]6]; and (3) enhancing the kinetics of the oxygen reduction reaction (ORR) at the cathode [1,2,[6][7][8]. Recent research has focused on mitigating the above challenges by increasing the operating temperature of PEMFCs from ~80 °C to >120 °C, resulting in so-called high temperature PEMFCs (HT-PEMFCs).…”

“…Operating at elevated temperature does introduce new difficulties in maintaining adequate hydration of proton exchange membranes such as Nafion ® , though this issue has been addressed with the use of phosphoric acid doped membranes which do not require external humidification [1,11,12]. Operating without external humidification not only simplifies balance of plant but also implies single phase, gaseous, transport in the gas diffusion layers (GDL) and flow channels, which makes reactant diffusion processes more facile [3,4]. To date, phosphoric acid-doped polybenzimidazole (PBI) membranes have been among the most successful acid doped membranes for HT-PEMFC applications [11][12][13][14][15][16][17][18][19][20].…”

Novel concept of polymer electrolyte membranes for high-temperature fuel cells based on ETFE grafted with neutral acrylic monomers

“…Compared to LTPEM fuel cells high temperature polymer electrolyte membrane (HTPEM) fuel cells have some important advantages. Firstly, humidification of the gases is not required and the probability of CO poisoning of the catalyst is significantly lowered at high temperature [2,[17][18][19][20][21]. Secondly, the fuel cell system may be more compact and technically less demanding.…”