Advanced carbon nanostructures for future high performance sodium metal anodes

Metallic sodium is a promising anode material due to its remarkably high theoretical capacity (1165 mA h g(-1)) and favorable redox voltage (-2.71 V versus the standard hydrogen electrode). However, unstable solid-electrolyte-interface (SEI) film and uncontrollable dendritic sodium formation induce low Coulombic efficiency, inferior cycling performance and even severe safety issues, dragging the sodium metal anode out of practical applications. Recently, the reviving of lithium metal and application of related characterization techniques bring a new era of the alkali metal anode. Carbonaceous materials have been employed as the interface engineering layer or the host of sodium metal. The advantageous of carbon nanostructure are including high mechanical strength, low weight, high conductivity, various nanoarchitecture, large surface area, easy functionalization, and sustainable. With these merits, sodium metal is guided and uniformly deposited into/through carbon nanostructures without dendrite formation as the stable sodium metal anode. In this review, we summarize the recent progress in the strategies of suppressing the dendritic sodium by carbon nanostructures, and comprehensively analysis the related dendrite depression mechanism. We expect that this work can provide important insights into scientific and practical application of sodium metal batteries.