Advancing High-Temperature PEMFCs: Synthesis and Characterization of Poly(2,5-benzimidazole) Nanoclay/SPVC Composite Membranes

High-temperature proton-exchange membrane fuel cells (HT-PEMFCs) have indeed emerged as highly efficient devices for energy conversion with numerous applications, ranging from portable electronics to transportation. The development of advanced electrolyte materials is imperative to enhance the PEMFCs’ stability and performance. Herein, we use sulfonated polyvinyl chloride (SPVC) and 2,5-benzimidazole-modified montmorillonite (AB-MMT) to create a series of novel composite electrolytes for PEMFC via a solution-casting method. PVC, well known for its excellent film-forming properties, is combined with modified MMT, a natural inorganic clay with a high surface area and ion-exchange capability (IEC). The composite polymer electrolyte membranes (PEMs) are further doped with phosphoric acid (PA) at varying concentrations. The structural, morphological, and electrochemical properties of prepared PEMs are systematically analyzed using FTIR, XRD, SEM, and impedance spectroscopies. The effect of PA on PEMs in terms of water uptake, mechanical and chemical stability, and ionic conductivity is also analyzed. The synergy between SPVC and AB-MMT creates a favorable microenvironment for ion transport within the membrane, contributing to enhanced PEMFC performance. The experimental results demonstrate that 10SBZMP exhibits a substantial increase in ionic conductivity, i.e., 0.069 at 150 °C and RH 98% with a power density of 0.252 W/cm². The development of advanced materials like these paves the way for more efficient and reliable fuel-cell technologies, contributing to the sustainable energy landscape of the future.