Dielectric polarization-mediated ion flux equalization enabling fast and stable sodium metal batteries

초록

Sodium metal batteries are promising candidates for cost-effective and high-energy storage systems, but their practical application is limited by unstable deposition and stripping behavior arising from nonuniform ion transport and concentrated interfacial electric fields. Therefore, regulating the local electric-field distribution and Na-ion flux at the metal/electrolyte interface is critical for suppressing dendrite growth and improving cycling stability. Here, we propose a porous and hierarchically organized barium titanate (BaTiO3) framework with a lamellar architecture that functions as a dielectric regulation layer capable of stabilizing sodium deposition. The vertically aligned porous dielectric framework induces strong interfacial polarization when wetted by the electrolyte, which greatly enhances the effective permittivity and redistributes the electric field around growing sodium nuclei. Computational analyses using electric-field simulations, molecular dynamics, and density functional theory confirm that the dielectric scaffold promotes more homogeneous ion flux and lowers the nucleation barrier. In situ optical observations further verify the suppression of tip-driven dendrite growth. Consequently, sodium cells incorporating the BaTiO3 membrane exhibit long-term cycling stability with low overpotential, maintaining approximately 10 mV for over 1600 hat 3 mA cm-2/3 mA h cm-2 and approximately 19 mV for over 1000 h even under high-current and high-capacity conditions of 10 mA cm-2/10 mA h cm-2. This work establishes a direct link between the dielectric response of an electrolyte-impregnated ceramic scaffold and sodium deposition dynamics, thereby contributing a dielectric polarization-mediated design principle for fast and stable sodium metal batteries. (c) 2026 Published by Elsevier B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

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