Oligomeric chain extender-derived poly(p-phenylene)-based multi-block polymer membranes for a wide operating current density range in polymer electrolyte membrane water electrolysis

Hydrocarbon-based membranes can extend the operating current range of a polymer electrolyte membrane water electrolyzer (PEMWE) because of their low gas permeability and high proton conductivity. However, increasing the ion exchange capacity for sufficiently high proton conductivity leads to poor mechanical stability and increased gas permeability for hydrocarbon-based membranes. This study presents a poly(p-phenylene)-based multiblock polymer with an oligomeric chain extender (CE-sPP-PPES) for improved mechanical stability and extended operating current range. With the introduction of a chain extender, the mechanical and chemical stability were notably enhanced. The effects of ion exchange capacity on mechanical properties, proton conductivity, and hydrogen crossover were investigated compared to a Nafion membrane. The CE-sPP-PPES-based PEMWE has a 2.1 times wider operating current range than a Nafion-based PEMWE because of its smaller ohmic overvoltage and lower gas crossover at an optimal ion exchange capacity, demonstrating the possibility of a new hydrocarbon-based membrane for PEMWE.

Automated summary

This study presents a new hydrocarbon-based membrane for polymer electrolyte membrane water electrolyzers, which improves mechanical stability and extends the operating current range. The introduction of a chain extender enhances the mechanical and chemical stability of the membrane. The new membrane has a wider operating current range compared to traditional membranes due to lower ohmic overvoltage and gas crossover at optimal ion exchange capacity.