LAUSR

To outline the role of dual-ion intercalation chemistry to reach sustainable energy storage, the present review aims to compare two types of batteries: widely accepted dual-ion batteries based on cationic and anionic co-intercalation versus newly emerged hybrid metal-ion batteries using the co-intercalation of cations only. Among different charge carrier cations, the focus will be on the materials that are able to co-intercalate monovalent ions (such Li + and Na + , Li + and K + , Na + and K + , etc.) or couples of mono- and multivalent ions (Li + and Mg 2+ , Na + and Mg 2+ , Na + and Zn 2+ , H + and Zn 2+ etc.). Furthermore, the review will be directed on these co-intercalation materials that are composed of environmentally benign and low-cost transition metals (such as Mn, Fe, etc.). The effect of the electrolyte on the co-intercalation properties will also be discussed. Finally, we think that the summarized knowledge on dual-ion energy storage would stimulate further research so that the hybrid metal ion batteries to become feasible in near future.