Polyoxometalate Ionic Sponge Enabled Dendrite‑Free and Highly Stable Lithium Metal Anode

Abstract Metallic lithium batteries are holding great promises for revolutionizing the current energy storage technologies. However, the formation of dendrite‐like morphology of lithium deposition caused by uneven distribution of Li + might cause severe safety concerns of batteries. In this study, a polyoxometalate (POM) cluster, H 5 PMo 10 V 2 O 40 (PMo 10 V 2 ), is added to the conventional electrolyte that can construct a lithium‐rich layer and inhibit the growth of Li dendrites effectively. The Li‐rich layer can fill any lack of lithium ions on the surface of the metal anode, making the electric field strength consistent across the anode surface, thereby inhibiting the formation of lithium dendrites. Consequently, a significantly prolonged cyclic lifespan is obtained for both Li/Li symmetric cells and Li/LiCoO 2 (Li/LCO) full cells. The cells with LCO positive maintains a high reversible specific capacity of 108.5 mAh g −1 after 300 cycles when electrolyte with PMo 10 V 2 additive is used, compared to 31.5 mAh g −1 for the untreated electrolyte. The findings indicate that POMs endowed as “ionic sponge” can be widely deployed in lithium metal batteries.