Montmorillonite as a sodium–ion–conductor interface for stable sodium metal anodes

The sodium anode is an ideal anode material in next-generation high-energy batteries due to its high theoretical capacity (1165 mA h g−1), low potential (−2.71 V) and natural abundance of Na resources. However, its practical application is restricted by irregular growth of sodium dendrites, which arises from unstable solid electrolyte interface (SEI) and high activity of sodium. To prevent dendrite growth, herein, a highly sodiophilic Na+-intercalated montmorillonite (Na-MMT) is directly embedded into sodium metal through a simple mechanical-rolling method. In the [email protected] composite anode, Na-MMT is highly dispersed into the whole sodium electrode, which affords a stable sodium–ion–conductor interface to provide faster diffusion channels and effectively lower the nucleation potential of Na, thus guiding the uniform deposition of sodium. By optimizing the mass ratio between sodium and montmorillonite, the as-prepared [email protected] anode exhibits superior plating/stripping reversibility (over 600 h at 1 mAh cm−2) and fast electrochemical kinetics (200 h at 4 mA cm−2 with a capacity of 4 mAh cm−2) in a carbonate-based electrolyte, which outperforms the performance of [email protected] and bare Na anodes. Moreover, the Na full cell ([email protected]||Na3V2(PO4)3) exhibits a long cycling stability over 1000 cycles and good rate capability (30 C).