Simple construction and reversible sequential evolution mechanism of nitrogen-doped mesoporous carbon/SnS2 nanosheets in lithium-ion batteries

Tin sulfide/nitrogen-doped mesoporous carbon (SnS2/NC) composite material is identified as a prospective anode material in lithium-ion batteries. Nevertheless, the evolution mechanism of SnS2/NC anode and the electronic conductivity of nitrogen-doped carbon to SnS2 are still unclear. Meanwhile, the preparation process of SnS2/NC is complicated and requires the use of harmful solvents. Herein, we propose a simple and green strategy for the construction of SnS2/NC nanosheets, and investigate its evolution mechanism and electronic conductivity in detail. DFT calculations substantiate the improved electronic conductivity and heightened Li adsorption af-finity after N doping. Profiting from the enhancement of electronic conductivity and Li adsorption affinity, the SnS2/NC anode attains a satisfactory discharge capacity (863.9 mAh/g at 100 mA/g over 100 cycles). Corre-spondingly, the assembled full cell achieves a capacity attenuation of solely 0.3% per cycle over 90 cycles. Upon lithiation, a sequential evolution mechanism, containing intercalation, conversion and alloying reactions, is reported on the basis of in-situ XRD, ex-situ XPS, and NMR characterizations. Additionally, ex-situ Raman reveals the reversible evolution of SnS2. These findings could afford significant reference and guideline for the evolution mechanism of other metal sulfides materials in energy storage areas.

Automated summary

A simple and green method was proposed for the synthesis of SnS2/NC nanosheets, and its evolution mechanism and electronic conductivity were investigated. The results showed improved electronic conductivity and Li adsorption affinity after N doping in SnS2/NC material. Benefitting from these enhancements, the SnS2/NC anode achieved satisfactory discharge capacity (863.9 mAh/g at 100 mA/g over 100 cycles) and the full cell exhibited a low capacity attenuation (0.3% per cycle over 90 cycles). The sequential evolution mechanism of intercalation, conversion, and alloying reactions during lithiation was revealed through in-situ XRD, ex-situ XPS, and NMR characterizations. These findings provide significant reference and guideline for the evolution mechanism of other metal sulfides materials in energy storage applications.