Metallic sodium anode has attracted much attention because of the low redox potential (-2.71 V vs. standard hydrogen electrode) and high theoretical capacity (1165 mAh g-1). More importantly, sodium anode is ideal to couple with sulfur and oxygen cathodes by providing necessary Na-ions for cycling, and the rational design of such configurations could considerably promote the battery energy density. Nonetheless, the practical applications of Na anodes are still rare due to some critical challenges such as the dendrite issues. Great efforts have been attempted with some success. Nonetheless, the practical development is still plagued as most research works were conducted with relatively small areal stripping/plating current densities and capacities. Here, we present a simple but very efficient approach to prepare dendrite-free sodium anodes that afford stable long-term cycling under practical high current densities and capacities. The hybrid sodium anodes can be fabricated using liquid metal by a facile alloying process at room temperature. The alloy protection layer allows fast electron transfer as well as sodium migration at the electrolyte-electrode interphase, which significantly suppresses the dendrite formation even at high current densities and large plating capacities of 8 mA cm-2 and 2 mAh cm-2 over 5000 cycles or 2500 hrs. Furthermore, the prototype full cells composed of hard carbon or Prussian blue counter electrodes demonstrate much improved rate and cycling performance. These promising results provide new perspectives for the design of stable sodium anodes for practical applications.

Fabrication of dendrite-free anodes with liquid metal for highly stable sodium metal batteries

2019 Fall National Meeting

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