Stability of a Fe-Rich Cathode Catalyst in an Anion Exchange Membrane Fuel Cell

Fe-rich alloys have been widely studied as catalyst materials for the cathodic oxygen reduction reaction (ORR) in hydrogen fuel cells, and many have shown high activities. The stability of Fe-rich catalysts has also been researched, and some studies have shown promising results using an accelerated stress test (AST), which uses a potential cycling method. However, for commercial fuel cell applications, such as standby power systems, the catalyst has to tolerate a high potential for a long period, which can not be represented by the AST test. In this paper, the cathode stability of a Fe-rich catalyst was studied using a standby cell potential of 0.9V, a potential shown to be challenging for the competing Pt catalysts. After 1500 hrs of testing, significant morphology changes of both the tested cathode and anode were found due to a Fe leaching process. Other alloy materials, including Ni, Cr, and Mn, were also found leached out along with the Fe species from the catalyst framework. The results are a cautionary note for using Fe based catalysts for AEMFC cathodes.

High bond reliability of newly developed silver alloy bonding wire

In this paper, a new type of silver (Ag) alloy bonding wire is introduced, and its bonding property and long term reliability are demonstrated. The new Ag wire, called GX2s, is developed as a cost-effective alternative to gold (Au) wire targeting at automotive electronics. The wire material is doped with added element, and its electrical resistivity is much lower than the conventional palladium (Pd) doped Ag wire. Highly accelerated stress test (HAST) and high temperature storage life (HTSL) test were carried out along with other bonding evaluations. The results show that GX2s has good bonding property and excellent long term bond reliability. Microstructural analyses of bond interface after the reliability tests were also conducted to investigate its improving mechanism. GX2s is a suitable alternative to Au wire for many applications including high temperature automotive devices.