SnS2/ZIF-8 Derived Two-dimensional Porous Nitrogen-doped Carbon Nanosheets for Lithium-sulfur Batteries

Lithium-sulfur batteries (LSBs) have attracted wide attention due to their high energy density, abundant raw material reserves and environmental friendliness. However, the shuttle effect of polysulfides, the large volume expansion during the reaction, and the poor electron conductivity of sulfur greatly limit their practical development. In this work, a ZIF-8 derived flower-like two-dimensional (2D) porous carbon nanosheet/sulfur composite (ZCN-SnS2-S) combined with SnS2 nanoparticles is designed as the cathode for LSBs. The unique 2D flower-shaped porous structure not only effectively alleviates the volume expansion during the reaction process, but also provides a fast channel for Li+ and electron transport. The presence of heteroatom N further promotes the adsorption of polysulfide. In particular, the polar SnS2 enhances the chemical adsorption on polysulfides, resulting in excellent electrochemical performance. The ZCN-SnS2-S electrode exhibits high reversible specific capacity of 948 mAh center dot g(-1) after 100 cycles at 0.2C (1C=1675 mA center dot g(-1)), demonstrating the capacity retention rate of 83.7%. Even at a high current density of 2C for 300 cycles, it still has a reversible specific capacity of 546 mAh center dot g(-1).

Automated summary

In this study, a ZIF-8 derived flower-like two-dimensional porous carbon nanosheet/sulfur composite was designed as the cathode for lithium-sulfur batteries. This material has a unique two-dimensional flower-shaped porous structure, which effectively alleviates the volume expansion issue and provides a fast channel for ion and electron transport. The presence of heteroatom N further promotes the adsorption of polysulfide, resulting in excellent electrochemical performance.