Abstract
Here we suggest a simple and novel method for the preparation of a high-performance self-humidifying fuel cell membrane operating at high temperature (>100 °C) and low humidity conditions (<30% RH). A self-humidifying membrane was effectively prepared by laminating together proton and anion exchange membranes composed of acceptor-doped SnP2O7 composites, Sn0.9In0.1H0.1P2O7/Sn0.92Sb0.08(OH)0.08P2O7. At the operating temperature of 100 °C, the electrochemical performances of the membrane electrode assembly (MEA) with this heterojunction membrane at 3.5% RH were better than or comparable to those of each MEA with only the proton or anion exchange membranes at 50% RH or higher.
Highlights
Polymer electrolyte membrane fuel cells (PEMFCs) have been intensively studied with the goal of commercialization [1,2,3]
Self-humidifying membranes are typically divided into three main types according to the materials incorporated in the membrane system: (1) Pt or Pt/C catalysts promote the reaction of hydrogen and oxygen from the anode and the cathode, respectively, to produce water in the membrane [14]; (2) hygroscopic metal oxides, such as SiO2 and TiO2, bound water molecules and maintain the hydration of the membrane [14,15]; and (3) proton-conductive materials, such as zirconium phosphate and heteropolyacids [16,17], improve the proton conducting behavior of the membrane at high temperature and low relative humidity (RH) condition
The conductivity of these membranes does not follow the Arrhenius-like dependency on temperature, because the RH decreases with increasing temperature (PH2O rather than RH was maintained constantly at the measurement)
Summary
Polymer electrolyte membrane fuel cells (PEMFCs) have been intensively studied with the goal of commercialization [1,2,3]. Self-humidifying membranes are typically divided into three main types according to the materials incorporated in the membrane system: (1) Pt or Pt/C catalysts promote the reaction of hydrogen and oxygen from the anode and the cathode, respectively, to produce water in the membrane [14]; (2) hygroscopic metal oxides, such as SiO2 and TiO2, bound water molecules and maintain the hydration of the membrane [14,15]; and (3) proton-conductive materials, such as zirconium phosphate and heteropolyacids [16,17], improve the proton conducting behavior of the membrane at high temperature and low RH condition These types of membranes are useful for the harsh operating conditions of PEMFCs, they have some problems that remain unsolved: (1) the heterogeneous dispersion of Pt may lead to local electronic conduction throughout the membrane [18]; (2) the increase of the additive contents may lead to increase the ohmic resistance of the membrane [19]; (3) the poor compatibility between the additive and membrane may decrease the mechanical properties of the membrane [20]. The fuel cell was operated between 50 and 200 ◦C
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