Air-breathing cathode for aluminum–air battery: From architecture to fabrication and evaluation

Aluminum–air battery is a kind of energy storage device use aluminum metal as negative material and oxygen in atmosphere as positive reactant, and it is also usually called a power generation device of semi-fuel cell. It has received great interest in both industrial and academic field owing to the high theoretical energy density, low cost, abundant aluminum reserves. In the more than 60 years since the first Al–air battery was invented in 1962, a series of Al–air battery such as aqueous primary battery, hydrogel-based primary battery, non-aqueous and aqueous rechargeable secondary battery, have been extensively studied from a fundamental research perspective. At the same time, from a practical application perspective, development and its application of prototype has experienced two major waves of research enthusiasm: first boom led by Alupower (a subsidiary of Alcan) from 1980 to 1995 after the 1973 oil embargo; another sparked by Alcoa and Phinergy since 2014. At present, aluminum has gradually been recognized as one of the important energy carriers. For Al–air battery, the air-cathode is one of the core components in battery, which affects the electrochemical performance and service life of battery. In this review, the principle & features, development history, and recent research progress of Al–air battery are systematically summarized. Specifically, the air-breathing cathode (covering architecture structure, gas diffusion layer, current collecting layer, catalyst layer and oxygen reduction catalyst), fabrication process, test & evaluation are comprehensively discussed. Finally, the existing technical hurdles and recommended future research perspectives of air-breathing cathode in Al–air battery are summarized and proposed to stimulate broader interest of researchers and engineers, and attempt to provide some insights for future development.