Superionic-conductor-modified nickel foam enables region-induced deposition for stable sodium anodes

Abstract

The practical application of Na metal batteries is severely hindered by uncontrolled Na dendrite growth and large volume fluctuations, which lead to safety hazards and poor cycling stability. Herein, we designed a composite 3D Ni foam skeleton modified with fast-ion conductor (FIC) networks to achieve dual ionic/electronic conductivity, enabling spatially guided Na deposition and confined growth. The FIC modification exhibits strong Na⁺ affinity, which ensures uniform ion distribution and directs Na deposition preferentially within the porous Ni framework rather than on its surface. This unique structure facilitates region-induced deposition and spatial confinement of Na metal, effectively suppressing dendrite formation and mitigating volume expansion. Moreover, the FIC network significantly enhances Na⁺ transport kinetics during plating/stripping processes, improving electrochemical reversibility. As a result, the FIC-modified 3D Ni host provides stable Na metal anodes with a prolonged cycling life and reduced polarization. The symmetric cells exhibit stable operation for 300 hours at 0.5 mA cm⁻² and 2 mAh cm⁻², while full cells demonstrate an outstanding capacity retention of 94.6% at 5C over 400 cycles. This work presents a rational electrode design strategy that combines guided ion redistribution and physical confinement to achieve dendrite-free Na metal anodes, providing new insights for developing high energy density Na-based batteries.