A 2023 update on the performance of ionic-liquid proton-exchange-membrane fuel cells

A mini-review is provided of the literature concerning performance proton-exchange-membrane fuel cells (PEMFCs) containing (immobilized) ionic liquids as possible electrolytes, focusing on papers reporting metrics (power and current densities). For over a decade, especially for combined heat power applications, there has been drive to design an ionic-liquid-holding membrane that could operate well under non-humidifying (water-free) conditions above 100°C. Such goal not yet achieved: reported densities are still below those traditional low-temperature cells. Other recent reviews have already pointed three main issues: poor conductivity, cathode (oxygen-reduction) kinetics, seepage liquid from membrane. In this review, IL-PEMFCs grouped into IL classes (protic, aprotic, polymerized), metric data summarized, cases producing top ten peak last 5 years discussed, conductivity mechanisms leading elucidated. Purely vehicular protic ILs appear be too slow, trend toward enhanced Grotthuss H + relays via polymerized revealed.