Long-life and efficient sodium metal anodes enabled by a sodiophilic matrix

Abstract

Sodium metal is a promising alternative anode for high-energy Na-based batteries due to its natural abundance, favorable redox voltage and remarkable theoretical capacity. However, unstable solid electrolyte interface (SEI) film, huge volume variation and uncontrolled Na dendrite growth, resulting in low Coulombic efficiency and limited span-life, have dragged the Na metal anode out of practical application. Herein, 3D hierarchical porous nickel foam matrix decorated by Fe2O3 nanosheets (Fe2O3 @Ni) is synthesized and served as a sodiophilic scaffold to reduce Na nucleation overpotential and achieve uniform Na deposition without dendrite growth. Consequently, the composite Na/Fe2O3 @Ni anode shows smaller hysteresis voltage at a high current density of 5 mA cm−2 and exhibits satisfactory cycling stability with a Coulombic efficiency of ~ 99.77% (up to 1000 cycles). When in couple with Na3V2(PO4)3 cathode, the full cell shows higher capacity and better cycling stability than the one with bare Na anode. The 3D porous nickel modified by Fe2O3 presents a new perspective for the anode design of sodium metal battery.