Polymer Electrolyte Membranes from Microporous Troger’s Base Polymers for Fuel Cells

Abstract

Fuel cells (FCs) have attracted much attention because of their high energy conversion efficiency and cleanliness. However, polyelectrolytes are a key component of FCs, and their cost and performance are not ideal at present, which is an obstacle to the development of FCs. Polymers of intrinsic microporosity (PIM) have attracted much attention as a class of membrane materials due to their three-dimensional pore structure, which can provide channels for ion transport. However, it remains challenging to prepare PIM membranes due to their poor solubility and brittleness. A novel soluble Troger’s base (TB)-PIM polymer is proposed in this paper. The prepared TB-based membranes with rigid and contorted backbones exhibit excellent dimensional stability (<8% swelling ratio at 60 °C), mechanical properties, and thermal stability and form subnanometer cavities to allow rapid ion transport. Therefore, the proton conductivity of the 4-(2-hydroxyethoxy)-1,3-phenylenediamine dihydrochloride (HEPD)/4,4′-diamine-3,3′-dimethyl-biphenyl (DMBP)-TB membrane is 58.3 mS/cm at 80 °C. The OH– conductivity of the HEPD/DMBP-QTB anion exchange membrane (AEM) is 105.9 mS/cm at 80 °C. Moreover, the single cell assembled with an HEPD/DMBP-QTB AEM showed a peak power density of 76.6 mW/cm2 in H2 air (CO2-free) at 60 °C.

Tröger’s Base Microporous Anion Exchange Membranes with Hyperbranched Structure for Fuel Cells

“…34,35 Recently, AEMs based on polymers of intrinsic microporosity (PIMs) have been widely used in many fields owing to their unique rigid contorted structure and excellent chemical stability. 2,36,37 Moreover, it is worth mentioning that the microporosity of those AEMs are beneficial for OH − transport. 38,39 Yang et al 40 has reported TB-based AEMs (named as DMBP-QTB) with V-shaped bridge structure TB units that obtained a OH − conductivity of 164 mS cm −1 at 80 °C, while the swelling ratio was 5% and the IEC value was only 0.82 mmol g −1 .…”

Advances in Polymers of Intrinsic Microporosity (PIMs)-Based Materials for Membrane, Environmental, Catalysis, Sensing and Energy Applications

“…In this regard, Du et al utilized a novel conductive PIM polymer based on Troger's base and used it to prepare a proton conductive membrane. 221 To impart the polymer conductivity, 4-(2-hydroxyethoxy)-1,3phenylenediamine dihydrochloride (HEPD) was introduced to the polymer backbone to form a hydrogen bond network. The resulting membrane was soaked in 1 M HCl solution for 3 h to produce a proton exchange membrane.…”

Ion Exchange Membranes: Constructing and Tuning Ion Transport Channels

“…These results led to other studies on TB-based AEMs. [157][158][159] In our subsequent work, we revealed the size-sieving effect of TB-based AEMs by performing diffusion dialysis experiments. [153] The DMBP-QTB membrane allowed cations with a size below 8.2 Å to diffuse quickly but retarded the passage of larger cations.…”