Abstract
In this study the preparation and properties of potassium hydroxide-doped meta-polybenzimidazole membranes with 20–30 μm thickness are reported as anion conducting polymer electrolyte for application in fuel cells. Dibutyl phthalate as porogen forms an asymmetrically porous structure of membranes along thickness direction. One side of the membranes has a dense skin layer surface with 1.5–15 μm and the other side of the membranes has a porous one. It demonstrated that ion conductivity of the potassium hydroxide-doped porous membrane with the porogen content of 47 wt.% (0.090 S cm−1), is 1.4 times higher than the potassium hydroxide-doped dense membrane (0.065 S cm−1). This is because the porous membrane allows 1.4 times higher potassium hydroxide uptake than dense membranes. Tensile strength and elongation studies confirm that doping by simply immersing membranes in potassium hydroxide solutions was sufficient to fill in the inner pores. The membrane-electrode assembly using the asymmetrically porous membrane with 1.4 times higher ionic conductivity than the dense non-doped polybenzimidazole (mPBI) membrane showed 1.25 times higher peak power density.
Highlights
Fuel cells are considered to be low-pollution and high-efficiency energy conversion technology which directly convert fuel energy into electricity
Anion exchange membranes still suffer from lower ionic conductivity than proton exchange membranes, since the electrical mobility of hydroxide ions is only 56% of that of protons In addition, the review found that the durability of most of the cells reported was limited to less than 1000 h [1]
Energies 2020, 13, 525 alkaline environments and with additional function to increase hydroxide ion conductivity are highly recommended for Solid alkaline fuel cells (SAFCs) [4,5,6,7,8,9,10,11]
Summary
Fuel cells are considered to be low-pollution and high-efficiency energy conversion technology which directly convert fuel energy into electricity. Solid alkaline fuel cells (SAFCs) are fuel cell technology using anion exchange membranes for the conduction of hydroxide ions from cathode to anode. Anion exchange membranes still suffer from lower ionic conductivity than proton exchange membranes, since the electrical mobility of hydroxide ions is only 56% of that of protons In addition, the review found that the durability of most of the cells reported was limited to less than 1000 h [1]. Anion conductive polymers must exhibit high chemical, mechanical and thermal stability, as well as good ion conduction ability. Most of the functional groups of anion conductive polymers used are quaternized ammonium groups, which show low chemical and thermal stability due to nucleophilic displacement or Hoffman elimination in alkaline environments above
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