Accelerated Durability Testing of Fuel Cell Stacks for Commercial Automotive Applications: A Case Study

Abstract

System durability is crucially important for the successful commercialization of fuel cell electric vehicles (FCEVs). Conventional accelerated durability testing protocols employ relatively high voltage to hasten carbon corrosion and/or platinum catalyst degradation. However, high voltages are strictly avoided in commercialized FCEVs such as the Toyota MIRAI to minimize these degradation modes. As such, conventional durability tests are not representative of real-world FCEV driving conditions. Here, modified start-stop and load cycle durability tests are conducted on prototype fuel cell stacks intended for incorporation into commercial FCEVs. Polarization curves are evaluated at beginning of test and end of test, and the degradation mechanisms are elucidated by separating the overvoltages at both 0.2 and 2.2 A cm-2. Using our modified durability protocols with a maximum cell voltage of 0.9 V, the prototype fuel cell stacks easily meet durability targets for automotive applications, corresponding to 15-year operation and 200,000 km driving range. These findings have been applied successfully in the development of new fuel cell systems for FCEVs, in particular the second-generation Toyota MIRAI.

Alternative and facile production pathway towards obtaining high surface area PtCo/C intermetallic catalysts for improved PEM fuel cell performance

“…† We acknowledge that the hydrogen underpotential deposition (H upd ) method for Pt-alloy complicates the quantitative ECSA measurement due to the altered electronic properties of PtCo, as this change affects the adsorption behaviour of hydrogen. 45,46 Still, the H upd method is widely used as a standard in literature for both Pt 47 and Pt-alloy catalysts 48,49 and is therefore employed in this work. As reported in the literature, the factor used to calculate the ECSA from the H upd charge was 210 mC cm −2 .…”

Alternative and facile production pathway towards obtaining high surface area PtCo/C intermetallic catalysts for improved PEM fuel cell performance

“…We acknowledge that the hydrogen underpotential deposition (Hupd) method for Pt-alloy complicates the quantitative ECSA measurement due to the altered electronic properties of PtCo, as this change affects the adsorption behaviour of hydrogen. 40,41 Still, the Hupd method is widely used as a standard in literature for both Pt 42 and Pt-alloy catalysts 43,44 and is therefore employed in this work. As reported in the literature, the factor used to calculate the ECSA from the Hupd charge was 210 µC cm-2.…”

Intelligent Chip-Controlled Smart Oxygen Electrodes for Constructing Rechargeable Zinc–Air Batteries with Excellent Energy Efficiency and Durability

“…Oxygen electrodes are usually gas–liquid–solid three-phase porous structures with catalysts, where porous carbon-supported catalysts are the preferential choice to achieve the best performance of oxygen electrodes. − Rechargeable oxygen electrodes are the key factor to realize rechargeable fuel cells, including efficient discharge and charge processes. For a single discharge process of the oxygen reduction reaction (ORR), the reported oxygen electrode can provide a discharge time of up to 5000 h. − However, the newly reported rechargeable oxygen electrodes can only provide a service life of 160–300 h due to the harmful effect during the charging process. − The huge difference in service life between the discharge and charge processes of rechargeable oxygen electrodes is a challenging project because of the following scientific and technical issues: The extra high theoretical potential and overpotential of the actual oxygen evolution reaction (OER) of water lead to the high energy consumption of water splitting accompanied by severe oxidative corrosion of carbon substrate during the charging process. , The continuously generated oxygen bubbles impact the ORR catalyst particles and the carbon-substrate material, resulting in premature peeling of catalysts, low energy efficiency, and short cycling life. , Even if the force is weak, the lasting impact still causes serious damage, similar to “constant water dropping will wear away a stone”. In addition, the corrosion of the carbon substrate will accelerate the premature peeling of the supported catalyst.…”