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

Abstract

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 affinity 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). Correspondingly, 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.