Next-Generation Nafion Membranes: Synergistic Enhancement of Electrochemical Performance and Thermomechanical Stability with Sulfonated Siliceous Layered Material (sSLM)

Nafion, while a benchmark proton exchange membrane (PEM) for fuel cells, suffers from significant performance degradation at elevated temperatures and low humidity due to dehydration and diminished mechanical stability. To address these limitations, this study investigated the development and characterization of Nafion nanocomposite membranes incorporating sulfonated silica layered materials (sSLMs). The inherent lamellar structure, high surface area, and abundant sulfonic acid functionalities of sSLMs were leveraged to synergistically enhance membrane properties. Our results demonstrate that sSLM incorporation significantly improved ion exchange capacity, water uptake, and dimensional stability, leading to superior water retention and self-diffusion at higher temperatures. Critically, the nanocomposite membranes exhibited remarkably enhanced proton conductivity, particularly under demanding conditions of 120 C and low relative humidity (i.e., 20% RH), where filler-free Nafion largely ceases to conduct. Single H2/O2 fuel cell tests confirmed these enhancements, with the optimal sSLM-Nafion nanocomposite membrane (N-sSLM5) achieving a two-fold power density improvement over pristine Nafion at 120 C and 20% RH (340 mW cm−2 vs. 117 mW cm−2 for Nafion). These findings underscore the immense potential of sSLM as a functional filler for fabricating robust and high-performance PEMs, paving the way for the next generation of fuel cells capable of operating efficiently under more challenging environmental conditions.