An acidic Zn–air battery (AZAB) is developed as a next-generation rechargeable metal–air battery. The use of a solid electrolyte enables alkaline Zn/Zn(OH)42− redox at the anode side and acidic oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) at the cathode side. The developed AZAB solves the persistent problems facing conventional Zn–air batteries, such as CO2 ingression, dendrite penetration, zincate loss, and low cell voltage. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.