Sodium–gallium alloy layer for fast and reversible sodium deposition

Abstract Sodium metal has been regarded as the potential alternative for metal batteries owing to its advantages of high theoretical capacity and abundant reserves. Nevertheless, propagation of Na dendrites can boost the interfacial instability of Na metal, retarding its practical implementation. Thus, the Na–Ga alloy layer is designed and fabricated by in situ rolling of metal Ga on the surface of Na metal. This alloy layer possesses good sodiophilicity, which can effectively protect Na metal and favor the uniform Na + deposition, obtaining the inhibition of Na dendrites growth. Consequently, the symmetric cells assembled by the alloy‐layer protected Na metal electrodes (NGAL‐Na||NGAL‐Na) have a long lifetime (468 h) even under a high plating/stripping capacity of 6 mAh cm −2 in carbonate electrolyte. The full battery of NGAL‐Na||Na 3 V 2 (PO 4 ) 3 is able to sustain an excellent rate capability of 100 mAh g −1 after 500 cycles at 10 C under ambient temperature. This work provides a new route to prevent metal anodes from severe dendrite growth, and paves the way toward safer and stable‐performing metal‐based rechargeable batteries.