Covalent bonding-triggered pore-filled membranes for alkaline fuel cells

Pore Filled Ion-Conducting Materials Based on Track-Etched Membranes and Sulfonated Polystyrene

Abstract

Synthesis of proton-conducting materials based on track-etched membranes from polyvinylidene fluoride and sulfonated cross-linked polystyrene is described. The synthesis has been carried out by filling the pores of the original or gamma-irradiated track-etched membrane by copolymerization of styrene/divinylbenzene followed by sulfonation of polystyrene with chlorosulfonic acid. The resulting membranes have been studied by scanning electron microscopy and ATR IR spectroscopy. Membrane ionic conductivity, hydrogen gas permeability, ion-exchange capacity, and water absorption were measured. The ionic conductivity at 30°C reaches 51.7 mS/cm, which is almost three times higher than for Nafion®212 membranes; however, the gas permeability of the obtained materials also increases simultaneously.

Membranes Based on Polyvinylidene Fluoride and Radiation-Grafted Sulfonated Polystyrene and Their Performance in Proton-Exchange Membrane Fuel Cells

Proton-exchange membranes based on gamma-irradiated films of PVDF and radiation-grafted sulfonated polystyrene with an ion-exchange capacity of 1.8 meq/g and crosslinking degrees of 0 and 3% were synthesized. A solvent-free, environmentally friendly method of styrene grafting from its aqueous emulsion, with a styrene content of only 5 vol.% was used. Energy dispersive X-ray mapping analysis showed that the grafted sulfonated polystyrene is uniformly distributed throughout the membrane thickness. The obtained materials had a proton conductivity up to 132 mS/cm at 80 °C and a hydrogen permeability of up to 5.2 cm²/s at 30 °C, which significantly exceeded similar values for Nafion^®-212 membranes. The resulting membranes exhibited a H₂/O₂ fuel cell peak power density of up to 0.4 W/cm² at 65 °C. Accelerated stability tests showed that adding a crosslinking agent could significantly increase the stability of the membranes in the fuel cells. The thermal properties and crystallinity of the membranes were investigated through differential scanning calorimetry and X-ray powder diffraction methods. The conductivity, water uptake, and mechanical properties of the membranes (stress–strain curves) were also characterized.

Ultrathin and Super Strong UHMWPE Supported Composite Anion Exchange Membranes with Outstanding Fuel Cells Performance

For high-performance anion exchange membrane fuel cells (AEMFCs), the anion exchange membrane (AEMs) should be as thin as possible to reduce the ohmic resistance. However, the mechanical stability of ultrathin AEMs cannot be guaranteed, as well as a huge risk of gas (H₂ &O₂ ) permeation. In this work, composite AEMs based on ultrahigh molecular weight polyethylene (UHMWPE) are prepared by in situ bulk polymerization. The as-prepared composite membranes can be as thin as 4 µm, and possess super high strength beyond 150 MPa. It also shows extremely low hydrogen permeation, low water uptake, low dimensional swelling, high conductivity, and good alkaline stability. In addition, the fuel cell performance based on the ultrathin composite AEMs exhibits outstanding peak power density of 1014 and 534 mW cm^-2 for H₂ -O₂ and H₂ -Air (CO₂ -free) at 65 °C, respectively, as well as good short-term durability.

New block poly(ether sulfone) based anion exchange membranes with rigid side-chains and high-density quaternary ammonium groups for fuel cell application

We report a series of novel poly(ether sulfone) based anion exchange membranes (AEMs) with relatively good stability due to their rigid side-chains and heterocyclic quaternary ammonium groups. The AEMs show appropriate performance in AEM fuel cells.