Enhancing Polymer Electrolyte Membrane Fuel Cells with Ionic Liquids: A Review

Abstract

Polymer electrolyte membrane fuel cells (PEMFCs) represent a promising clean energy solution. However, their widespread adoption faces hurdles related to component optimization. This review explores the pivotal role of ionic liquids (ILs) in enhancing PEMFC performance, focusing on their role in polymer electrolyte membranes, catalyst modification, and other components. By addressing key obstacles, ILs provide a pathway towards the widespread commercialization of PEMFCs. In the realm of PEMFC membranes, ILs have shown great potential in improving proton conductivity, mechanical strength, and thermal stability. Additionally, the utilization of ILs as catalyst modifiers has shown promise in enhancing the electrocatalytic activity of electrodes and reduce their agglomeration, thereby augmenting catalytic performance. Furthermore, ILs can be tailored to optimize the catalyst‐support interaction, ultimately enhancing the overall fuel cell efficiency. Their unique properties, such as high oxygen solubility and low volatility, offer advantages in terms of reducing mass transport and water management issues. This review not only underscores the promising advancements achieved thus far but also outlines the challenges that must be addressed to unlock the full potential of ILs in PEMFC technology, offering a valuable resource for researchers and engineers working toward the realization of efficient and durable PEMFCs.

Electrostatic Correlations Lead to High Capacitance in Zwitterion-Containing Thin Films

“…Figure 1 shows the route for synthesizing the novel zwitterion (EG2IM-TFSI) from N-ether diethylene glycolsubstituted imidazole and potassium chlorotrifluoromethylsulfonyl chloride using procedures from the literature. 51,52 The identity and purity of this compound were confirmed by 1 H NMR, 13 C NMR, 19 F NMR, FT-IR, +ESI MS, and X-ray fluorescence (XRF) (characterization data is available in the Supporting Information Figures S2−S6). Purification of the compound is critical to minimize ionic impurities.…”

“…The usefulness of ILs in devices such as batteries and fuel cells is, however, limited by the competing migration rate of the component ions under an applied electric field. − The high ionic conductivity of ILs can also be detrimental in organic electrochemical transistors, often causing slower than desired switching speeds due to their intercalation into the semiconductor. − Zwitterions, in which the cationic and anionic functional groups are covalently bound, are molecules with zero net charge, making them promising alternatives to ILs. Their tethered structure allows the rotational reorientation of molecules under an applied electric field, avoiding its translational motion and allowing the mobility of only the target ions. ,,− So far, zwitterions have primarily been investigated as additives to other electrolytes in batteries, but their application as a whole electrolyte is gradually increasing. , Zwitterions have also been used as highly polar dopants and functional coatings to affect the molecular orientation in liquid crystals to facilitate low driving voltage and large contrast smart windows for flexible wearable devices. , More broadly, zwitterions have been extensively studied for applications such as surfactants, surface coatings, and catalysts − and typically pose a significantly lower risk to aquatic species compared to their IL counterparts …”