A rational microstructure design of SnS2–carbon composites for superior sodium storage performance

Abstract

Sodium ion batteries (SIBs) have attracted ever-growing attention as promising candidates for large-scale energy storage applications, due to the abundant sodium resources and their low cost. Nevertheless, it is still a significant challenge to realize superior electrode materials with high capacity and good cyclability. To address these problems, herein, a rational microstructure of the SnS₂–carbon composite has been designed for superior performance, which consists of MWNTs as a carbon matrix, the SnS₂ nanosheet (NS) as an active material, the outer carbon coating as a protection layer, as well as the interior void space for volume accommodation. As an anode material for SIBs, the so-produced MWNT@SnS₂ NS@C electrode delivered a high initial capacity of 910 mA h g⁻¹ at 100 mA g⁻¹ and a good retention of 78% after 100 cycles. The sodium storage mechanism of SnS₂ was systematically studied through CV, ex situ XPS, and ex situ HRTEM characterization studies, disclosing the reversible conversion and alloying reactions of SnS₂ during sodiation/desodiation processes. Moreover, ex situ TEM was further applied to clarify the relationships between the SnS₂–C microstructure and sodium storage performance. Our result represents a significant step towards rational design electrodes with high capacity and cyclability for sodium ion batteries.