SnO₂ Quantum Dots Enabled Site-Directed Sodium Deposition for Stable Sodium Metal Batteries

Abstract

Dendrite growth has been severely impeding the implementation of sodium (Na) metal batteries, which is regarded as one of the most promising candidates for next-generation high-energy batteries. Herein, SnO₂ quantum dots (QDs) are homogeneously dispersed and fully covered on a 3D carbon cloth scaffold (SnO₂-CC) with high affinity to molten Na, given that SnO₂ spontaneously initiates alloying reactions with Na and provides low nucleation barrier for Na deposition. Molten Na can be rapidly infused into the SnO₂-CC scaffold as a free-standing anode material. Because of the affinity between SnO₂ and Na ion, SnO₂ QDs can effectively guide Na nucleation and attains site-directed dendrite-free Na deposition when combined with the 3D CC scaffold. This electrochemically stable anode enables almost 400 cycles at ultrahigh current density of 20 mA cm^-2 in Na symmetric battery and delivers superior cycling performance and reversible rate capability in Na-Na₃V₂(PO₄)₃ full batteries.