Electrochemical Evaluation of Pellet-Type Anodes for Refuelable Aluminum-Air Batteries

Abstract This study presents a refuelable aluminum-air battery (AAB) system using pellet-type aluminum (Al) anodes, enabling rapid mechanical replenishment and supporting resource circulation. A comparative analysis conducted for the first time with conventional plate-type anode revealed that galvanic coupling with the anode support and structural blocking significantly affect discharge performance. Despite these factors, the pellet anodes achieved a competitive energy density of 2,381 Wh/kg, benefiting from a high reactive surface area and reduced system weight. Furthermore, Al resources were experimentally recovered from the electrolyte with at least 94% efficiency, marking the first demonstrated implementation of Al resource recovery in an AAB system. These results provide new insights into optimizing pellet-type anodes, improving performance-limiting factors, and integrating recyclable system architecture, thereby advancing the development of practical and sustainable AAB technologies.