Exploring Nafion's microstructural changes and the impact on the performance of PEMFC under high-energy radiation

Abstract

PEMFCs, crucial for space energy needs, rely on Nafion for proton conductivity and durability. High-energy radiation in space can degrade PEMFC performance. Therefore, in-depth research on the microstructural evolution of Nafion under high-energy radiation and its impact on PEMFC's performance is of great significance for promoting the application of fuel cell technology in the space field. This work combines experimental and computational simulation methods to propose the evolution mechanism of C–O–C rupture and –COOH generation in Nafion under high-energy radiation. The new molecular structure formed has increased chain spacing and free volume, enhanced water absorption and swelling properties, and decreased structural stability. When the radiation absorption dose exceeds 400 kGy, Nafion completely becomes brittle and cannot be used. The change in Nafion at 0–400 kGy structure resulted in a significant overall decrease in mechanical properties (decreased by 73.76 %), proton conductivity (decreased by 40.59 %), output power density (from 480.00 to 30.00 mW/cm²), hydrogen permeation (from 2.26 to 60.75 mA/cm²), and open-circuit voltage (from 1.01 to 0.27 V). This study not only enhances the understanding of Nafion's structural evolution and performance degradation under high-energy radiation but also provides important research directions for developing high-performance PEMFCs suitable for the space environment.