A Hybrid Mg2+/Li+ Battery Based on Interlayer‐Expanded MoS2/Graphene Cathode

Abstract The hybrid Mg 2+ /Li + battery (MLIB) is a very promising energy storage technology that combines the advantage of the Li and Mg electrochemistry. However, previous research has shown that the battery performance is limited due to the strong dependence on the Li content in the dual Mg 2+ /Li + electrolyte. This limitation can be circumvented by significantly improving the diffusion kinetics of Mg 2+ in the electrode, so that both Li + and Mg 2+ ions can be utilized as charge carriers. Herein, a free‐standing interlayer expanded MoS 2 /graphene composite (E‐MG) is demonstrated as a cathode for MLIB. The key advantage of this cathode is to enable the efficient intercalation of both Mg 2+ and Li + . The E‐MG electrode displays a reversible capacity of ≈300 mA h g −1 at 20 mA g −1 in an MLIB cell, corresponding to a specific energy density up to ≈316.9 W h kg −1 , which is comparable to that of the state‐of‐the‐art Li‐ion batteries (LIBs) and has no dendrite formation. The composite electrode is stable against cycling with a coulombic efficiency close to 100% at 500 mA g −1 . This new electrode design represents a significant step forward for building a safe and high‐density electrochemical energy storage system.