Tailoring alloy-reaction-induced semi-coherent interface to guide sodium nucleation and growth for long-term anode-less sodium-metal batteries

Sodium metal batteries are emerging as promising energy storage technologies owing to their high-energy density and rich resources. However, the challenge of achieving continuous operation at high areal capacity hinders the application of this system. Here, a robust two-dimensional tin/sodium-tin alloy interface was introduced onto an Al substrate as an anode via an industrial electroplating strategy. Unlike the widely accepted in situ formation of Na15Sn4 alloys, the formation of Na9Sn4 alloys results in a semi-coherent interface with sodium due to low lattice mismatch (20.84%), which alleviates the lattice stress of sodium deposition and induces subsequent dense sodium deposition under high areal capacity. In addition, the strong interaction of Sn with anions allows more PF6- to preferentially participate in the interfacial solvation structure, thereby facilitating the formation of a thin (10 nm) NaF-rich solid electrolyte interface. Therefore, the substrate can withstand a high areal capacity of 5 mA h cm-2, exhibiting a high average Coulombic efficiency of 99.7%. The full battery exhibits long-term cycling performance (600 cycles) with a low decay rate of 0.0018% per cycle at 60 mA g-1. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)/(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Sn (sic)Na(sic)(sic)(sic)(sic)Na15Sn4(sic)(sic)(sic)(sic), (sic)(sic)(sic)Na9Sn4(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(20.84%), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic), Sn(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)PF6-(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic) (sic)(10 nm)(sic)(sic)(sic)NaF(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)/(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic). (sic)(sic), (sic)(sic)(sic)5 mA h cm-2(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)99.7% (sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)60 mA g-1(sic), (sic)(sic)(sic)(sic)(sic)(sic)600(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)0.0018%.