Amorphous–Crystalline High-Entropy Electrocatalysts for H 2 Evolution in High-Power Aluminum-Based Fuel Cells

Metal-air batteries have long captured the imagination of researchers and industries alike, admired for their promise of cost-effective, safe, and eco-friendly energy storage. Yet, their journey to full commercialization has been hindered by challenges such as limited power density and troublesome carbonate deposition. In a groundbreaking leap forward, we introduce an alkali/acid aluminum–hydrogen fuel cell by coupling alkaline aluminum anode oxidation with a high-entropy alloy (HEA)-driven acidic hydrogen evolution reaction (HER), which transcends these limitations by replacing the sluggish oxygen reduction reaction with the swift and efficient HER. To this end, a hybrid amorphous–crystalline HEA of FeCoNiMnRu has been developed as a cathode electrocatalyst for HER. The diversity of its local structures is key to its high catalytic activity, and the amorphous structure exhibits even greater stability. The hybrid aluminum–hydrogen fuel cell achieves a record-breaking peak power density of 964 mW cm–2 at current densities as high as 1319 mA cm–2, surpassing nearly all alkaline aluminum-air batteries reported to date. Beyond high power density, it also demonstrates impressive longevity upon 220 h of continuous operation at 200 mA cm–2 while maintaining a near-perfect Faradaic efficiency (>99%) for hydrogen production. The hydrogen-production fuel cell may pave the way for high-efficiency power delivery and open up scalable avenues for high-efficiency hydrogen synthesis.