Defect engineering constructs two-dimensional metal sulfoselenide with expanded interlayers for fast and efficient sodium ion storage.

Leveraging abundant natural reserves and lower cost profiles, sodium-ion batteries (SIBs) are poised to supersede lithium-ion batteries (LIBs) within the domain of large-scale energy storage systems. Many achievements have been made in improving the properties of anodes in SIBs from the aspects of nanostructure and surface modification. Recently, the incorporation of anionic species into metal sulfides via defect engineering has emerged as an innovative strategy to boost sodium storage capabilities. Herein, a nitrogen-doped carbon-coated two-dimensional metal sulfide with partial selenium substitution (SnSSe@NC) is constructed and utilized as an anode material for SIBs. The substitution of Se effectively expanded the interlayer distance of SnS, making it more favorable for Na intercalation/deintercalation. The lattice defects introduced thereby have catalyzed the swift nucleation of conversion-alloying reaction products, acting as effective stabilizers and dispersants. The establishment of heterogeneous interfaces has expedited ion/electron transport, thereby enhancing electrochemical kinetics. Furthermore, the external carbon layer has mitigated the volumetric expansion of the electrode material. This innovative strategy has endowed the anodes with superior cyclic performance (506.6 mA h g at 0.1 A g after 200 cycles) and rate capability (312.4 mA h g at 1 A g after 500 cycles) in SIBs, offering a novel pathway for the design of high-performance metal sulfide anode materials.