Homogeneous Metallic Deposition Regulated by Porous Framework and Selenization Interphase Toward Stable Sodium/Potassium Anodes

Abstract Sodium (Na) metal has been considered as the most promising anode for achieving next‐generation battery system with high energy density and low cost. Nevertheless, the uncontrolled dendrites growth, infinite volume expansion and unstable solid/electrolyte interphase severely hinder the practical application of Na metal anode. Herein, a functional composite Na anode (Na₂Se/Cu@Na) is achieved via infusing molten Na into the porous copper framework modified by cuprous selenide nanosheets. Combining experimental studies and theoretical calculations, the 3D framework and derivatives of Na₂Se/Cu can synergistically buffer the volume expansion, redistribute Na⁺ flux, promote ions migration, and induce uniform Na⁺ deposition. Benefiting from these merits, the symmetrical cell of Na₂Se/Cu@Na demonstrates a stable cycle lifespan over 500 h at 1 mA cm⁻² in carbonate electrolyte. And the full battery paired with Na₃V₂(PO₄)₃ cathode delivers a stable capacity of 97 mAh g⁻¹ after 800 cycles at 10 C. Furthermore, this structured framework can also be employed to construct composite potassium (K) anode and an outstanding cycle performance is achieved in the symmetrical cell (operating for 1000 h at 0.5 mA cm⁻²). This study paves a significant way of designing structured Na (K) metal anodes for synergistically improving the electrode stability.