摘要：
穿梭效应、低导电性、巨大的体积膨胀是阻碍硫正极实际应用的主要原因.目前,解决上述问题最有效的措施是合理设计固硫碳材料结构,但是,碳基固硫材料的制备通常很复杂并且成本较高.因此,发展一种有效且低成本的方法来制备高能硫电极的碳基材料十分必要.在此,本文提出一种基于熔融盐法的生物衍生的氮掺杂多孔碳材料(BNPC).BNPC有序的蜂窝结构有利于硫和固定多硫化物并且容纳循环过程中的体积膨胀,高度石墨化促进了硫正极氧化还原反应动力学.此外,掺杂的氮不仅可以提高BNPC的导电性,还为硫和多硫化物提供固定位点,这在抑制穿梭效应方面起到关键作用.因此,S@BNPC电极呈现出1189.4 mA?h/g的高初始比容量,在0.2C下循环300圈后仍然有703.2 mA?h/g的容量,衰减速率每圈只有0.13％.这项工作为碳基固硫材料的大规模应用提供了很大的可能性.%Shuttle effect, poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes. Currently, rational structure designing of carbon-based sulfur hosts is the most effective strategy to address the above issues. However, the preparation process of carbon-based sulfur hosts is usually complex and costly. Therefore, it is necessary to develop an efficient and cost-effective method to fabricate carbon hosts for high-performance sulfur cathodes. Herein, we reported the fabrication of a bio-derived nitrogen doped porous carbon materials (BNPC) via a molten-salt method for high performance sulfur cathodes. The long-range-ordered honeycomb structure of BNPC is favorable for the trapping of polysulfide (PS) species and accommodates the volumetric variation of sulfur during cycling, while the high graphitization degree of BNPC favors the redox kinetics of sulfur cathodes. Moreover, the nitrogen doping content not only enhances the electrical conductivity of BNPC, but also provides ample anchoring sites for the immobilization of PS, which plays a key role in suppressing the shuttle effect. As a result, the S@BNPC cathode exhibits a high initial specific capacity of 1189.4 mA?h/g at 0.2C. After 300 cycles, S@BNPC still maintains a capacity of 703.2 mA?h/g which corresponds to a fading rate of 0.13％ per cycle after the second cycle. This work offers vast opportunities for the large-scale application of high performance carbon-based sulfur hosts.
