Low fuel crossover anion exchange pore-filling membrane for solid-state alkaline fuel cells

A novel anion exchange pore-filling membrane allowing low liquid fuel permeation while maintaining hydroxide ion conduction has been developed for use in solid-state alkaline fuel cells (SAFCs). Mechanical stability of the exterior porous substrate suppresses swelling of the interior polyelectrolyte and controls the inner water to be wholly bound water even under fully humidified conditions. Using this membrane, hydroxide ion conduction through bound water has been discovered for the first time. At the same time, we also have clarified that this bound water effectively reduces permeation of the high-energy-density liquid fuels, methanol and ammonia, which is beneficial in the design of efficient SAFCs.

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► Anion exchange pore-filling membrane for solid-state alkaline fuel cell was made.
► The membrane has only bound water and no free water even with full humidification.
► Hydroxide ion conduction through bound water was discovered using the membrane.
► Effective reduction of liquid fuels permeation through bound water was clarified.