Review of current progress in non-aqueous aluminium batteries

Research on aluminium batteries is rapidly gaining momentum as a potential alternative to established battery chemistries such as lithium ion. Aluminium is abundant, recyclable, and due to its three-electron redox reaction it offers the potential for high specific energy and power. It can also be used as a metal negative electrode due to its dendrite-free plating behaviour at relevant conditions in room temperature ionic liquid electrolytes. With these electrolytes, a battery made entirely of abundant elements can also be envisaged. However, in order to commercialise aluminium batteries, researchers must still overcome formidable challenges, because no positive electrode material has yet demonstrated efficient reversible storage of aluminium ions. This review paper provides a critical summary of the research to date. We present a discussion of the chemistry of the electrolytes, the deposition and dissolution behaviour of aluminium, and the various cathode materials that have been attempted. We also place non-aqueous aluminium batteries in context with other battery systems and provide an outlook of future research direction, and potential future applications. Using clear graphics to explain the various concepts, we intend this review to provide a broad and clear introduction to the field for researchers new to the area. •Aluminium batteries and their research are justified in the context of other electrochemical energy storage systems.•A detailed explanation of the different operating mechanism of non-aqueous aluminium batteries is provided.•The chemistry of the most common electrolyte, AlCl3-[EMIm]Cl, is explained.•The deposition/dissolution characteristics of aluminium are considered.•A comprehensive review of positive electrodes that have been attempted is undertaken.