Carbon-Coated SnS Nanosheets Supported on Porous Microspheres as Negative Electrode Material for Sodium-Ion Batteries

SnS has outstanding theoretical capacity and is a promising electrode material for sodium-ion batteries. However, intrinsic low conductivity and huge volume changes upon sodium extraction/insertion limit its application. Herein, hierarchical hollow carbon spheres covered with S,N-doped carbon-coated SnS nanosheets synthesized by a multistep process are reported, including a hard sacrificial template, hydrothermal reaction, and annealing treatment. The prepared C@SnS@C samples are characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The nanosized SnS provides capacity; S,N-doped carbon coating protects the integrated structure. Consequently, due to the compositional and structural merits, the optimized electrode has a high specific capacity of around 420 mAh g⁻¹ at 0.2 A g⁻¹, high rate performance (200 mAh g⁻¹ at 10 A g⁻¹), and good cycling stability with 95% (i.e., 305 mAh g⁻¹ at 0.5 A g⁻¹) of the initial capacitance after 100 cycles. Kinetic analyses reveal that a substantial capacitive contribution results in better rate performance of the C@SnS@C electrode.