Rong Qian, Yuwen Chao, Liu Peng, Cheng Feixiang, Xia Shubiao
College of Chemistry and Environmental Science Qujing Normal University Qujing China.
Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming China.
Int J Energy Res. 2022 Sep 18. doi: 10.1002/er.8733.
Despite the high theoretical capacity and energy density of lithium-sulfur (Li-S) batteries, the development of Li-S batteries has been slow due to the poor electrical conductivity and the shuttle effect of the electrode materials, resulting in low sulfur utilization and fast long-term cycling capacity decay. The modified carbon materials are often used as sulfur hosts to significantly improve the cycling performance of the materials, but also bring high-cost issues. Here, the porous carbon materials are synthesized quickly and conveniently by the microwave cross-linking method using discarded medical masks as carbon sources and concentrated sulfuric acid as solvent. However, poor surface and structural properties limit the application of materials. The porous carbon material is modified with p-toluene disulfide and urea as the sulfur and nitrogen sources by the microwave cross-linking method, which not only improves the porosity and specific surface area of the porous carbon material, but also improved the electrical conductivity and interlayer spacing of the material. As synthesized SN-doped porous carbon is employed as the sulfur host, which exhibits a high discharge capacity (1349.3 mAh g) at 0.1°C, the S-porous C/S, N-porous C/S, and SN-porous C/S can maintain 78.1, 43.9, and 59.5% of the initial capacity after 500 cycles. The results indicate that the doping of S and N atoms provides sufficient active sites for the chemisorbed lithium polysulfides (LiPSs) to improve the reaction kinetics of the materials.
尽管锂硫（Li-S）电池具有较高的理论容量和能量密度，但由于电极材料的电导率差和穿梭效应，Li-S电池的发展一直很缓慢，导致硫利用率低和长期循环容量快速衰减。改性碳材料常被用作硫宿主，以显著提高材料的循环性能，但也带来了高成本问题。在此，以废弃医用口罩为碳源、浓硫酸为溶剂，通过微波交联法快速便捷地合成了多孔碳材料。然而，较差的表面和结构性能限制了材料的应用。采用对甲苯二硫化物和尿素作为硫源和氮源，通过微波交联法对多孔碳材料进行改性，不仅提高了多孔碳材料的孔隙率和比表面积，还改善了材料的电导率和层间距。合成的SN掺杂多孔碳用作硫宿主，在0.1°C时表现出高放电容量（1349.3 mAh g），S-多孔C/S、N-多孔C/S和SN-多孔C/S在500次循环后可保持初始容量的78.1%、43.9%和59.5%。结果表明，S和N原子的掺杂为化学吸附的多硫化锂（LiPSs）提供了足够的活性位点，从而改善了材料的反应动力学。
