Cost‐Effective Passive Ammonia Fuel Cells via Synergistic Integration of Optimized Membrane Electrode Assembly and Prototype

Passive ammonia fuel cells (PAFCs) offer modular adaptability but face dual challenges: limited power density and dependency on noble metals. Here, a comprehensive strategy is presented to address these issues through coordinated materials and system design. Pre-oxidized nickel substrates direct the formation of β-phase NiOOH/Ni₃P (β-NiOOH/Ni₃P) heterointerfaces in anode, significantly enhancing ammonia oxidation reaction (AOR) kinetics with a high current density of 171 mA cm^-2 at 0.7 V. A spinel-structured MnCo₂O₄/C cathode catalyst demonstrates remarkable ammonia tolerance and outperforms Pt/C in stability. A polytetrafluoroethylene/layered double hydroxide (PTFE/LDH) composite membrane is also introduced, which effectively reduces ammonia crossover. Their integration with an optimized graphite prototype further enhances PAFCs' efficiency and stability. This synergistic multi-phase optimization enables record-breaking performance for non-noble metal-based PAFCs, achieving a peak power density (PPD) of 61 mW cm^-2 and an open circuit voltage (OCV) of 0.87 V (outperforming Pt-based PAFCs). Stable discharge can be sustained by the present PAFC for 9 h by replenishing the ammonia supply. This work establishes a prototype-to-performance strategy for cost-effective PAFC, highlighting the potential of non-noble metal catalysts in ammonia electrochemical energy conversion.