Finely Adjusted Intrinsically Microporous Copolyimide Electrolyte Membranes for Fuel Cells Operating in a Wide Temperature Range

Abstract

The development of proton exchange membrane fuel cells (PEMFCs) that operate over a wide temperature range without additional humidification systems remains challenging. In this work, wide-temperature-range proton exchange membranes (PEMs) were constructed from novel Tröger’s base (TB)-based intrinsically microporous copolyimides (co-PIs) finely adjusted by incorporating crown ether units into chain backbones. Owing to the strong siphoning effect of existing microporosity and hydrogen bonds or the acid–base interactions of crown ether and TB units with phosphoric acid (PA) and/or H2O, the PA-doped co-PI membrane electrode assemblies (MEAs) can easily operate stably from 30 to 160 °C under H2/air conditions even without any external humidifiers. Regarding its single-cell performance, PI-TB-N30C achieved maximum power densities of 250 and 361 mW cm–2 at 80 and 160 °C, respectively, under anhydrous conditions. In addition, PA-doped co-PI MEA can accomplish long-term stable operation under low or high temperatures for 120 h. The structural architectures for PEMs based on finely adjusted microporous co-PIs extend beyond the current capabilities of existing PEMFCs.

Soluble Polyimides Containing Benzocyclobutene Moieties: Synthesis, Cross-Linking Behavior, and Physical and Gas Transport Properties

“…Polyimide (PI) is an organic polymer material known for its excellent overall performance. Owing to its excellent heat and chemical resistance, exceptional film-forming ability, and superior mechanical and physical properties, − it is widely used in automotive components, medical tubes, humidity sensors, fuel cells, optical films, and gas separation membranes. − In the area of gas separation, PI has attracted considerable attention because most commercial gas separation membranes are still derived from commodity polymers, for example, polysulfone and cellulose acetate, which are unsuitable for harsh industrially relevant conditions, such as high temperature and pressure. , …”

Modification of Hydrophobic Diacid Units for Enhanced Poly(crown ether) Anion-Exchange Membrane Performance

“…Polymer electrolyte fuel cell (PEFC) technology is considered as an environment-friendly energy conversion device to address fuel resource depletion and global warming due to its near-zero pollution and excellent energy conversion efficiency. – PEFCs can be classified as proton exchange membrane fuel cells (PEMFCs), which function in acidic conditions, and anion-exchange membrane fuel cells (AEMFCs), which operate in an alkali environment. , PEMFCs have been applied in some fields due to their good fuel cell performances. Nevertheless, the high cost associated with the utilization of perfluorinated membranes and Pt-based catalysts hinders the large-scale commercial application of PEMFCs .…”