Ultrathin heterostructured ZnS/SnS2/CuS nanoflakes filled in N-doped carbon nanoboxes as novel cathode hosts for Li-SeS2 batteries

Abstract

Hollow heterostructured hosts play a pivotal role in enhancing the efficiency of lithium-selenium sulfide batteries by addressing volume fluctuations, shuttle effects, and reaction kinetics of active sulfur/selenium-based species. However, constructing hollow hosts with multiphase interfaces and a unique design for optimizing the utilization and conversion of aggregated SeS2 within their cavities remains a formidable challenge. In this context, we introduce a novel concept−triphasic ZnS/SnS2/CuS heterostructured ultrathin nanoflakes filled in N-doped carbon nanoboxes (ZnS/SnS2/CuS@NC)−as an innovative host for Li-SeS2 batteries. The ZnS/SnS2/CuS@NC host facilitates dense contact between polar conductive sulfides and aggregated SeS2 in the cores, thereby enhancing the actual capacity of SeS2. Experimental and theoretical analyses reveal that the ZnS/SnS2/CuS@NC host possesses high binding energies and catalytic activity for polysulfides/polyselenides, attributed to increased adsorption interfaces, imbalanced charge distribution among interfaces, and high electrical conductivity. The sophisticated structure and composition of the ZnS/SnS2/CuS@NC-SeS2 cathode yield impressive performance, achieving a high capacity of 565.9 mAh g−1 after 500 cycles at 1.5 C, and a notable area capacity of 4.16 mAh cm−2 at 0.5 C (5.3 mg cm−2). This study unveils, for the first time, the functional role of the triphasic metal sulfide host and provides in-depth insights into its atomic-level accelarating conversion mechanism towards SeS2. The research findings pave the way for designing and optimizing hollow hosts, offering a promising direction for realizing high-performance Li-SeS2 batteries and beyond.