SnO<sub>2</sub> Quantum Dots Enabled Site-Directed Sodium Deposition for Stable Sodium Metal Batteries.

Xu, Ying; Matios, Edward; Luo, Jianmin; Li, Tao; Lu, Xuan; Jiang, Shuaihu; Yue, Qin; Li, Weiyang et al. · Nano Lett · 2021

basic_science · Level V

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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, SnO<sub>2</sub> quantum dots (QDs) are homogeneously dispersed and fully covered on a 3D carbon cloth scaffold (SnO<sub>2</sub>-CC) with high affinity to molten Na, given that SnO<sub>2</sub> spontaneously initiates alloying reactions with Na and provides low nucleation barrier for Na deposition. Molten Na can be rapidly infused into the SnO<sub>2</sub>-CC scaffold as a free-standing anode material. Because of the affinity between SnO<sub>2</sub> and Na ion, SnO<sub>2</sub> 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<sup>-2</sup> in Na symmetric battery and delivers superior cycling performance and reversible rate capability in Na-Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> full batteries.