Performance optimization of high energy density aluminum-air batteries: Effects of operational parameters and electrolyte composition

Aluminum-air (Al-air) batteries are promising candidates for high energy-density applications due to their lightweight design, cost-effectiveness, and high theoretical energy output. This study investigates the performance optimization of two rotating disk prototypes, with prototype-1 systematically exploring the combined effects of critical parameters, including anode-cathode distance (ACD), electrolyte flowrate, and temperature- an area previously underexplored. Prototype-1 achieved high peak power densities of up to 155.87 mW/cm² and energy densities of 987.17 mWh/g. Insights gained are used to design prototype-2, which features a larger active electrode surface and an electrode cartridge system for improved usability and maintenance. Prototype-2 focused on the impact of electrolyte composition, comparing KOH and NaOH at varying concentrations. KOH achieved a peak power density of 142.4 mW/cm² and energy densities of 2778.40 mWh/g, outperforming NaOH, which displayed a peak of 120 mW/cm² energy densities of 2385.02 mWh/g. While KOH demonstrated higher energy density and superior discharge stability, NaOH exhibited greater stability at elevated concentrations and slightly better current and energy efficiency at lower concentrations. This study provides a comprehensive understanding of the synergistic effects of operational parameters and electrolyte composition on Al-air battery performance. The findings offer valuable insights for optimizing design and operational strategies, paving the way for the development of high-performance Al-air battery systems.