Synergistic Effect of 3D Flexible Framework with Sodiophilic Mesoporous SnO₂ Nanosheet Arrays on Dendrite-Free Sodium Metal Batteries

Although tremendous efforts have been dedicated to promote the electrochemical stability of sodium metal batteries (SMBs), the uncontrollable dendrites growth and inevitable side reactions at the sodium (Na) anode/electrolyte interface have not been effectively resolved. In this work, a flexible and functionalized 3D framework with mesoporous SnO2 nanosheet arrays (SnO2@CC-12) is fabricated to serve as a sodiophilic matrix toward dendrite-free Na metal anode. The mesoporous SnO2 nanosheet arrays provide abundant sodiophilic sites and sufficient internal voids, which can not only accelerate electron transport to reduce the local current density of Na anode surface but also manipulate the Na+ flux deposition to suppress the growth of Na dendrites. Therefore, the SnO2@CC-12-Na symmetric cell exhibits an ultralow overpotential of 9 mV and superior Na plating/stripping stability over 2200 h at 1.0 mA cm–2. Moreover, the full cells using Na3V2(PO4)3 cathode show favorable high-rate performance and impressive long cycling stability with 95.1% capacity retention over 1000 cycles at 500 mA g–1. This work may provide a new insight into the design of functionalized interface layer with high sodiophilicity toward dendrite-free SMBs.