One-pot synthesis of hierarchical CoS/NC@MoS/C hollow nanofibers based on one-dimensional metal coordination polymers for enhanced lithium and sodium-ion storage.

Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodium-ion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the construction of heterogeneous interfaces of multimetal sulfides remain great challenges. Herein, a hierarchical 1T-MoS/carbon nanosheet decorated CoS/N-doped carbon (CoS/NC@MoS/C) hollow nanofiber was designed and constructed via a one-pot hydrothermal method using a cobalt-based coordination polymer nanofiber. This nanofiber can transform in-situ into conductive N-doped carbon hollow fibers embedded with active CoS nanoparticles, enabling the epitaxial growth of MoS nanosheets. Consequently, the CoS/NC@MoS/C composites achieve exceptional lithium/sodium-ion storage performance. Compared to MoS/C microspheres and CoS/NC hollow nanofibers alone, the CoS/NC@MoS/C hollow nanofibers deliver higher discharge capacities (1085.9 mAh g for lithium-ion batteries (LIBs) and 748.5 mAh g for sodium-ion batteries (SIBs) at 100 mA g), better capacity retention (910 mAh g for LIBs and 636.5 mAh g for SIBs after 150 cycles at 100 mA g), and increased cycling stability (407.2 mAh g after 1000 cycles for SIBs at 1000 mA g). Furthermore, the kinetic analysis shows that the lithium/sodium-ion storage processes of the CoS/NC@MoS/C electrode are mainly controlled by pseudocapacitance behavior. The excellent electrochemical properties can thus be ascribed to the synergy of the MoS/C nanosheets with the enlarged interlayer spacing, good conductivity of the carbon layers, and the CoS nanoparticles embedded in the hollow nanofibers with extensive reaction sites.