Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

Abstract

High molecular weight, highly PA-doped s-PBI membranes have been developed with robust mechanical properties and excellent proton conductivities (>0.1 S cm -1 ) at elevated temperatures (>100°C). These membranes show high PA loadings of 30-35 mol PA/PBI, and average tensile stress and strain of 0.804 MPa and 69.64%, respectively. Proton conductivities were dependent on the acid doping level and measured between 0.1 and 0.25 S cm -1 at 180°C, a pronounced increase over most phosphoric acid-doped sulfonated PBI membranes to date. Preliminary fuel cell testing with hydrogen fuel and air or oxygen oxidants was performed at temperatures greater than 100°C without external feed gas humidification and show excellent performance (0.62-0.68 V at 0.2 A cm -2 and 160°C, hydrogen/air; 0.69-0.76 V at 0.2 A cm -2 and 160°C, hydrogen/oxygen). Initial performance stability studies were conducted for ∼3000 h and indicate great promise as high temperature membranes, with a degradation rate of 30 μV h -1 .

Characterizing Voltage Losses in an SO2Depolarized Electrolyzer Using Sulfonated Polybenzimidazole Membranes

“…The same electrode, obtained from BASF, was used on both the anode and cathode, and contained 1.0 mg/cm 2 platinum (Pt) catalyst loading. 21 The electrolyzer operation and acid-concentrations measurements are similar to previous works. 13 The exception is that water to humidify the SO 2 stream was directly injected into the feed stream at the entrance to the electrolyzer using a micropump rather than using a humidification bottle.…”

“…21 The mono-sodium-2-sulfoterephthalate was combined with 3,3',4,4'-tetraaminobiphenyl in a 3-necked resin kettle equipped with nitrogen flow and an overhead mechanical stirrer. The solutions were heated to 195…”

Hexafluoroisopropylidene based sulfonated new copolytriazoles: investigation of proton exchange membrane properties

“…Therefore, many efforts have been made in order to replace these materials. Several hydro carbon basedsulfonated aromatic PEM materials, such as sulfonated poly(arylene ether sulfone)s (9)(10)(11)(12)(13)(14)(15), sulfonated poly(arylene ether ketone)s (16)(17)(18)(19), sulfonated polyimides (20)(21)(22)(23)(24)(25), sulfonated poly(benzimidazole)s (26)(27)(28), sul fonated polybenzothiazoles (29)(30)(31) and sulfonated poly triazoles (32)(33)(34)(35)(36)(37), have been developed in the recent years. It is well known, that the hydrocarbonbased sulfonated aromatic copolymers display lower proton conductivity in comparison to the perfluoro sulfonated polymers, due to poor phase separation between the hydrophilic and hydrophobic domains and the weak acidic nature of SO 3 H group (38).…”

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

“…Another type, sulfonated PBI has a relatively high conductivity of 0.037 S/cm at 170 • C and zero hydration [58], and Mater and Benicewicz reported another new type of PBI with an impressive conductivity of 0.367 S/cm at 180 • C for a block copolymer consisting of sulfonated PBI segments [59,60]. The longest reported lifetime for a HT-PEM fuel cell is 18,000 h under steady-state conditions [61].…”