Engineering Sodium Metal Anode with Sodiophilic Bismuthide Penetration for Dendrite-Free and High-Rate Sodium-Ion Battery

Sodium (Na) metal batteries with a high volumetric energy density that can be operated at high rates are highly desirable. However, an uneven Na-ion migration in bulk Na anodes leads to localized deposition/dissolution of sodium during high-rate plating/stripping behaviors, followed by severe dendrite growth and loose stacking. Herein, we engineer the Na hybrid anode with sodiophilic Na3Bi-penetration to develop the abundant phase-boundary ionic transport channels. Compared to intrinsic Na, the reduced adsorption energy and ion-diffusion barrier on Na3Bi ensure even Na+ nucleation and rapid Na+ migration within the hybrid electrode, leading to uniform deposition and dissolution at high current densities. Furthermore, the bismuthide enables compact Na deposition within the sodiophilic framework during cycling, thus favoring a high volumetric capacity. Consequently, the obtained anode was endowed with a high current density (up to 5 mA.cm(-2)), high areal capacity (up to 5 mA.cm(-2)), and long-term cycling stability (up to 2800 h at 2 mA.cm(-2)). (C) 2022 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company.

Automated summary

This study addresses the issue of uneven sodium ion migration in sodium metal battery anodes by designing a Na3Bi penetration structure. Compared to pure sodium, the reduced adsorption energy and diffusion barrier on Na3Bi enable even deposition and dissolution of sodium at high current densities, leading to increased volumetric capacity.