Multifunctional sandwich-structured double-carbon-layer modified SnS nanotubes with high capacity and stability for Li-ion batteries

Abstract

Tin monosulfide (SnS) anodes have attracted much attention for lithium-ion batteries (LIBs) due to their excellent chemical stability, high theoretical specific capacity and outstanding reversibility. However, the slow kinetics and large volume expansion of intrinsic SnS electrodes in the conversion reaction process restrict their application to a certain extent. To address the poor conductivity and volume fluctuation, N-doped double-carbon-layer protective hierarchical structures decorating SnS nanotubes (N-DCSNs) are introduced by in situ polymerization directed using a g-C₃N₄ soft template. Particularly, N-doped double carbon layers provide fast transport channels for electrons and ions, affording decent conductivity and rapid ionic diffusion rate. Most importantly, the volume expansion of SnS during the charge–discharge cycles can be buffered owing to the confinement effect of the double carbon layer. Synergistic effects of N-DCSNs enhance the mechanical integrity and electrochemical kinetics during the charge–discharge process, leading to high-capacity retention and long-term stability properties. As a remarkable anode for LIBs, the N-DCSN electrode delivers high capacities of 911.5 and 511.3 mA h g⁻¹ at 0.2 and 1.0 A g⁻¹ after 270 and 1000 cycles, respectively. The feasible and versatile structure design can offer new ideas for the preparation and regulation of other transition metal sulfide anode materials, and provide a relevant experimental basis for the further development of lithium/sodium storage equipment.