Microwave-assisted graphite as a catalysts free cathode for highly efficient aluminum-based electrochemical energy systems

Abstract

Aluminum-air batteries (AABs) hold promises for scalable energy storage, but developing cost-effective, high-performance cathodes remains challenging. We present an innovative microwave-assisted (MW) fabrication method to create a high disordered graphite as a catalyst-free cathode for enhancing the performance of an aluminum electrochemical energy system (Al-EES). Using MW-treated graphite with a catholyte ie., sodium persulfate (Na₂S₂O₈) eliminates the need for traditional oxygen reduction reaction (ORR) cathodes, raising the device voltage from 1.46 V to 2.02 V and achieving an energy density of 2314 Wh/kg_Al. As a result, the MW process enriches charge transfer pathways, increases active sites, and boosts the electrocatalytic performance of the Na₂S₂O₈. Advanced characterization techniques, including Raman mapping, scanning electrochemical microscopy (SECM), and density functional theory (DFT) calculations, confirm enhanced graphitization and functionalization, leading to improved efficiency. This innovation streamlines the electrode design by replacing complex, high-cost cathodes (catalysts, air-breathing layer, binder, etc.). It allows the modified graphite to serve as both cathode and bipolar plate, reducing system costs by 90 % compared to conventional Al-air batteries. The advancements result in a peak power density of 161 mW cm⁻², 2.5 times higher than Al-air systems, and exceptional discharge performance, setting a new standard for cost-effective, high-performance Al-based energy conversion devices. Our results demonstrate a scalable, economically viable, and environmentally sustainable pathway for next-generation energy storage systems.