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.