Sodiophilic Zn/SnO2 porous scaffold to stabilize sodium deposition for sodium metal batteries

Abstract

Sodium is regarded as a promising electrode material in the post lithium ion battery era due to its high theoretical specific capacity of 1166 mAh g−1, low electrochemical potential (−2.71 V vs standard hydrogen electrode), low cost and high natural abundance. However, similar to lithium metal anode, sodium metal anode also shares the problems of uncontrollable dendrites growth, formation of unstable solid electrolyte interface and large volume change during repeated plating/stripping. Herein, a porous sodiophilic zinc metal framework modified with SnO2 surface layer is introduced on copper substrate and used as 3D current collector for sodium metal batteries in order to realize even deposition of Na, moderate the volume change and construct a stable solid electrolyte interface layer simultaneously. Theoretical calculations based on density functional theory are used to interpret the deposition behavior of the metallic Na on different current collectors. The electrochemical performance results show that the Cu/Zn/SnO2@Na symmetric cell can deliver an extremely low nucleation overpotential (0 mV), outstanding long-term rate performance over 1000 h and also can be cycled for around 700 h even at a high current density of 5 mA cm−2 for total capacity of 5 mAh cm−2. Cu/Zn/SnO2@Na//Na3V2(PO4)3 full cell is also constructed to display the feasible application of the designed Cu/Zn/SnO2 porous current collector in advanced sodium metal anode.