Co<sub>9</sub>S<sub>8</sub>/Porous Carbon Catalysts Boosting Lithium–Sulfur Batteries: NaCl Assisted-Carbothermal Reduction Preparation and Distribution of Relaxation Time Technique Assessment
Chengwei Zhang, Dongze Li, Yang Wang, Chunsheng Shi, Ning Wang, Biao Chen, Fei Ding
Abstract
Constructing composites of transition metal sulfide/carbon (TMSs) with carbon-based materials has been perceived as an effective catalyst for solving the “shuttle effect” of lithium polysulfides (LPSs) in lithium–sulfur batteries (LSBs). The scaled-up and facile method for preparing TMS/C composites and in situ characterization methods to evaluate the catalytic ability of these catalysts are worth developing. The reaction mechanism of a new one-pot facile synthesis of fabricating TMSs@S-doped porous carbon materials (including Co 9 S 8 /SPC, Ni 3 S 2 /SPC, and MnS/SPC) via carbothermal reduction MSO 4 was explored in this Article. Using this method and the NaCl as the water-soluble template, we prepared the Co 9 S 8 /S-doped three-dimensional porous carbon composite (3DSPC) as the host for S in LSBs that deliver excellent catalytic ability for LPSs. In situ electrochemical impedance spectroscopy was established at different voltages during the charge–discharge process. More importantly, the distribution of relaxation time technique was used for the analysis of the EIS data to identify different electrode reactions. The polarization resistance values did not increase significantly during the discharge process in the cell with Co 9 S 8 /3DSPC, indicating that the Li 2 S/Li 2 S 2 has uniformly deposited on the surface of the nano Co 9 S 8 particles due to the presence of more catalytic active sites reducing the internal resistance. The DRT validates its feasibility as an evaluation method for the catalytic ability of polysulfides. The characterization can guide the development of catalyst design for LPSs in LSBs.