Optimization of the Cathode Catalyst Layer for Boosting Direct Ammonia Fuel Cell Performance by Orthogonal Tests

The design of the cathode catalyst layer (CCL) for theoxygen reductionreaction is critical to improving the performance of anion-exchangemembrane-based direct ammonia fuel cells (AEM-DAFCs) due to the impactof ammonia crossover. Herein, the effects of three factors (cathodecatalyst loading, binder type, and binder content) and their correspondingthree levels on the CCL have been investigated to achieve optimalcell performance by the orthogonal test for the first time. CCLs arecharacterized by scanning electron microscopy, mercury intrusion porosimetry,and contact angle measurements, which further verify the reliabilityof the orthogonal test results. The results show the following orderof influence on the cell performance: binder type > binder content> cathode catalyst loading. These factors affect the mass transportand the number of three-phase interfaces in the CCL by changing itsthickness, surface morphology, pore structure, and hydrophobicity,thus affecting the cell performance. An AEM-DAFC with a champion peakpower density (PPD) of 158.6 mW cm(-2) has been achievedunder the optimal combination of cathode catalyst loading (2 mg cm(-2)), binder type (poly-(tetrafluoroethylene) (PTFE)),and binder content (15 wt %). This work provides an alternative avenueto improve the performance of AEM-DAFCs using state-of-the-art catalystsand binders through rapid optimization of the CCL structure in thefuture.