Norbornene-based acid-base blended polymer membranes with low ion exchange capacity for proton exchange membrane fuel cell

In recent decades, the prominence of environmental and energy issues has advanced the use of clean energy. Fuel cell is one of the cleanest and widely used energy conversion device. Proton exchange membrane has functions of proton transfer and electrode isolation in fuel cell. Commercial proton exchange membranes have high cost and other performance problems, requiring new alternatives. In this study, a series of blended membranes were prepared, and the effects of different sulfonated polyimide (SPI) in polynorbornene-3,6-bridged methylene-1,2,3,6-tetrahydro-N-(6'-aminohexyl)-cis-phthalimide (PNBN)/sulfonated polyimide (SPI) acid-base blended membranes to achieve high proton conductivity at low ion exchange capacity (IEC) have been investigated. Under the same experimental conditions, the chemical stability of the blended membranes was compared with pristine PNBN membrane. The results show that the acid-base blending membranes PNBN/SPI showed low IEC of 0.071 to 0.200 mmol/g. And the ion conductivity of the blending membranes was measured at different temperatures and PNBN/SPI-15% can achieve 22.133 mS/cm at 80 degrees C. And we found that the ion conductivity of the blended membranes increased with the increase of SPI ratio, which is due to the combined effect of acid-base pair and hydrophilic groups providing ion channels. Moreover, the operation of fuel cells can be achieved at low IEC of 0.200 mmol/g, and the power density of proton exchange membrane fuel cell (PEMFC) assembled with the blended membranes can increase to 104.26 mW cm(-2), indicating that the blending membranes are good for PEMFC.

Automated summary

The fuel cell is a clean and widely used energy conversion device, and the proton exchange membrane is a crucial component in the fuel cell. However, commercial proton exchange membranes have high cost and performance issues, necessitating the exploration of new alternatives. In this study, blended membranes were prepared using different sulfonated polyimide (SPI) in polynorbornene-3,6-bridged methylene-1,2,3,6-tetrahydro-N-(6'-aminohexyl)-cis-phthalimide (PNBN)/sulfonated polyimide (SPI) acid-base blended membranes, and their effects on achieving high proton conductivity at low ion exchange capacity (IEC) were investigated. The results showed that the acid-base blending membranes exhibited low IEC and increased ion conductivity with the increase of SPI ratio, making them suitable for use in proton exchange membrane fuel cells (PEMFC).