Design towards recyclable micron-sized Na<sub>2</sub>S cathode with self-refinement mechanism.

Lu, Suwan; Liu, Yang; Xu, Jingjing; Weng, Shixiao; Xue, Jiangyan; Liu, Lingwang; Wang, Zhicheng; Qian, Can et al. · Nat Commun · 2024

basic_science · Level V

Where this comes from

Abstract

Sodium sulfide (Na<sub>2</sub>S) as an initial cathode material in room-temperature sodium-sulfur batteries is conducive to get rid of the dependence on Na-metal anode. However, the micron-sized Na<sub>2</sub>S that accords with the practical requirements is obstructed due to poor kinetics and severe shuttle effect. Herein, a subtle strategy is proposed via regulating Na<sub>2</sub>S redeposition behaviours. By the synergistic effect from both conductive structure and cuprous sulfide (Cu<sub>2</sub>S) catalysis, the micron-sized Na<sub>2</sub>S particles are broken down and redeposited to nano-size during the initial cycle which can be fully utilized in subsequent cycles. Consequently, the Na<sub>2</sub>S/CPVP@Cu<sub>2</sub>S||Na cell delivers excellent cyclability (670 mAh g<sub>S</sub><sup>-1</sup> after 500 cycles) with a remarkable average Coulombic efficiency over 99.7% and rate capability (480 mAh g<sub>S</sub><sup>-1</sup> at 4 A g<sub>S</sub><sup>-1</sup>). Besides, the Na-free anodes are used to prove the application prospects. This work provides an innovative idea for utilizing micron-sized Na<sub>2</sub>S and offers insights into its conversion pathway.