Understanding short-side-chain perfluorinated sulfonic acid and its application for high temperature polymer electrolyte membrane fuel cells

Abstract

The great demand for high-temperature operation of polymer electrolyte membrane fuel cells (PEMFCs) has been well answered by short-side-chain perfluorinated sulfonic acid (SSC-PFSA) membranes through a good balance between transport properties and stability. It has been evidenced that fuel cells assembled with SSC-PFSA possess higher and more stable performance at elevated temperature up to 130 C compared to that of fuel cells based on conventional long-side-chain (LSC) PFSA (Nafion®) membranes. Moreover, the shorter side-pendent chains and the absence of the ether group and of the tertiary carbon also endow SSC-PFSAs with better durability, making them more suitable for working at harsh conditions in fuel cell systems. This critical review is dedicated to summarizing the properties of SSC-PFSA and providing insight into an understanding of their micro-morphologies, mass diffusion, enhanced proton transportation and their mutual correlation. Diversified measurement techniques applied to investigate the evolution of micro-morphologies, unique diffusion and transportation properties of SSC-PFSAs are reviewed. Despite the higher crystalline and higher water absorption of SSC-PFSAs than those of LSC-PFSAs, the notably less developed and less interconnected ionic clusters in SSC-PFSAs lead to lower mass permeability, and hence the high water uptake is not as well translated into transportation performance as expected. The factors and reasons for the enhanced electrochemical performance of SSC-PFSAs such as higher proton conductivity at elevated temperatures and low humidity conditions are also discussed and understood. Highlights of recent advances in SSC-PFSAbased membranes for fuel cell applications at wider temperature ranges are summarized as general references for researchers to further prompt the development of SSC-PFSAs. The SSC-PFSAs based membranes give a bright future for the next generation of high-temperature PEMFCs.

Physicochemical properties of Aquivion/fluorine grafted sepiolite electrolyte membranes for use in PEMFC

“…However, physicochemical characteristics of pristine Nafion membrane are limiting the PEMFC operation range. The proton conductivity of the electrolyte membrane declines due to dehydration as PEMFCs are operated at intermediate temperature, that is above 100 C. In addition, among PFSA materials, Aquivion has been selected for its enhanced proton conductivity and thermal stability compared with those of Nafion due to short-side-chain, larger crystallinity, higher glass transition temperature, and lower equivalent weight [5,6]. Aquivion membranes are also chemically stable and can operate at temperatures higher than Nafion membrane.…”

Study of Azoles as Bifunctional Additives for Proton Exchange Membranes Melt-Processing from LSC and SSC Perfluorosulfonic Acid Ionomers

“…Furthermore, imidazole was shown to be unsuitable for fuel cell applications, due to the observed diffusion and absorption of its oxidation products on the surface of the Pt catalyst that reduces considerably the catalyst active surface (7). The high electronic density (high pKa) of imidazole ring seems to be an explanation.…”

Role of Nitrogen‐Doped Carbon Nanofibers Inside Polymer Membranes for Enhancing Fuel Cell Performance

“…The N‐CNF matrix showed approximately 8 μm thickness, which is clearly isolated from the Aquivion polymer sandwich‐like structure. In the thermogravimetric analysis (TGA) in Figure a, three stages of weight loss appeared; evaporation of water in the membrane, decomposition of sulfonated groups, and breakdown of the backbone and side chains . Here, the same behavior of both membranes in the TGA curve below 100 °C suggests that the N‐CNF in the membrane does not affect humidification for the membrane, depending on the hydroscopic properties.…”