Synergistic engineering of hollow flower-like Co9S8/MoS2 heterostructures with N/S co-doped and carbon coating layer for enhanced sodium storage

Rechargeable sodium-ion batteries (SIBs) offer significant promise for the energy market due to their environmental friendliness, low cost, and high energy density. However, challenges such as volume expansion and sluggish reaction kinetics during charging/discharging limit the widespread practical development of SIBs. Herein, a hollow flower-like heterostructure composite material, g-Co 9 S 8 /MoS 2 @NS-C, was synthesized via a glucose-assisted hydrothermal method followed by a one-step water bath process, where g stands for glucose-derived carbon acting as the carbon structure. The hollow Co 9 S 8 framework derived from ZIF-67 provides structural stability, and accommodates volume changes during redox reactions. The Co 9 S 8 /MoS 2 heterointerface establishes a built-in electric field, which can promote the fast migration of electrons/ions. In addition, doped N and S heteroatoms within the carbon matrix and conductive carbon coating layer may cooperate synergistically not only to improve total conductivity, but also to generate more active sites. Consequently, when used as the anode of sodium batteries, the composite can exhibit a capacity value of 433.4 mAh g −1 after 200 cycles at 2 A g −1 , achieving superior capacity retention. Additionally, the electrode can still offer a particular capacity of 386.6 mAh g −1 at 5 A g −1 . Remarkably, it maintains 377.0 mAh g −1 after 200 cycles even at −30 °C under 50 mA g −1 , demonstrating exceptional low-temperature stability. This research can offer a possible route to high-performance anodes for SIBs.