Boosting the Stable Na Storage Performance in 1D Oxysulfide

Abstract

Exploring new structure prototypes and phases by material design, especially anode materials, is essential to develop high‐performance Na‐ion batteries. This study proposes a new anode, Na₂Cu_2.09O_0.50S₂, with a 1D crystal structure and outstanding Na storage performance. In view of the crystal structure of Na₂Cu_2.09O_0.50S₂, [Cu₄S₄] chains act as electrically conducting units enabling conductivity as high as 0.5 S cm⁻¹. The residual Na₄[CuO] chains act as ionically conducting units forming rich channels for the fast conduction of Na ions as well as maintaining the structural stability even after Na ion extraction. Additional ball milling on the as‐prepared Na₂Cu_2.09O_0.50S₂ significantly decreases its grain size, achieving a capacity of 588 mA h g⁻¹ with a high initial Coulombic efficiency of 93% at 0.2 A g⁻¹. Moreover, the Na₂Cu_2.09O_0.50S₂ anode demonstrates outstanding rate capability (408 mA h g⁻¹ at 2 A g⁻¹) and extending cyclic performance (82% of capacity retention after 400 cycles). The general structural design idea based on functional units may offer a new avenue to new electrode materials.