Novel Bimetallic Activated Center Alloying Mechanism Positive Electrodes for Aluminum Storage.

Aluminum is the most abundant metal element in the Earth's crust, thus developing the rechargeable aluminum-ion batteries (AIBs) provides an ideal opportunity to realize cells with pleasing energy-to-price ratios. However, the further development of AIBs is plagued by the scarcity of suitable positive electrode materials. Here, for the first time, a tin-based alloy positive electrode material for AIBs, Co 3 Sn 2 wrapped with graphene oxide (Co 3 Sn 2 @GO composite) is well-designed and investigated to understand the aluminum storage behavior. A series of experimental measurements and theoretical calculations results reveal that a novel "bimetallic activated center alloying reaction" aluminum storage mechanism is occurred on the prepared Co 3 Sn 2 positive electrode. The reversible alloying/de-alloying process in AlCl 3 /[EMIm]Cl ionic liquid, where both Co and Sn in Co 3 Sn 2 alloys react electrochemically with Al 3+ to form Al x Sn and Al y Co is first put forward. This study delineates new insights on the aluminum storage mechanism, which may guide to ultimately exploit the energy benefits of "bimetallic activated center alloying redox".