百香果皮基原位氮掺杂多孔碳/硫复合正极的制备及储锂性能

以生物质百香果皮为碳源，KHCO₃为活化剂，采用同步活化碳化方法制备原位氮掺杂的分级多孔碳材料，将其与单质硫复合制得多孔碳/硫正极材料。通过X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）等表征技术对制备材料的物相组成、微观形貌、比表面积及孔结构进行研究分析。同时，利用紫外可见吸收光谱研究了多孔碳对多硫化物的吸附作用，用恒电流充放电测试了不同硫含量（60%~80%）的多孔碳/硫复合正极材料的电化学性能。结果表明，制得的多孔碳材料为无定型，具有1 093 m²·g^-1的高比表面积和0.63 cm³·g^-1的孔容；丰富的多孔结构和原位氮掺杂对多硫化物的物理化学协同吸附作用，有效降低了锂硫电池的“穿梭效应”，提高了电池的放电比容量和循环性能。硫含量为60%的多孔碳/硫复合材料，在0.05C和0.2C倍率下可释放1 057.7和763.4 mAh·g^-1的高初始放电比容量，在1C的高倍率下循环300次后的保持率为75%。

Preparation and Lithium-Storage Performance of In-Situ Nitrogen Doped Porous Carbon/Sulfur Composite Cathodes Derived from Passiflora Edulis Peel

An in-situ nitrogen-doped hierarchical porous carbon material was prepared via a simultaneous activation/carbonization process using biomass passiflora edulis peel and KHCO₃ as carbon source and activator, respectively. The as-prepared porous carbon was composited with elemental sulfur to obtain the porous carbon/sulfur cathode material. The phase composition, microstructure, specific surface area, and pore structure of the as-prepared materials were investigated by these characterization techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and so on. Also, the adsorption effect of polysulfides using porous carbon as an adsorbing material was studied by UV-Vis absorption spectroscopy. The electrochemical performances of porous carbon/sulfur composite cathodes with different sulfur content from 60% to 80% were studied by galvanostatic charge/discharge test. Results showed that the asprepared material was amorphous porous carbon with a high specific surface area of 1 093 m²·g^-1 and pore volume of 0.63 cm³·g^-1. The physicochemical synergistic adsorption of polysulfides through abundant porous structure and in-situ nitrogen doping effectively suppresses the "shuttle effect" of lithium-sulfur batteries, whilst improving the discharge capacity and cycle performance. Consequently, the porous carbon/sulfur composite cathode with a sulfur content of 60% delivered high initial discharge capacities of 1 057.7 and 763.4 mAh·g^-1 at 0.05C and 0.2C, respectively. At a high current rate of 1C, a long life of 300 cycles with a capacity retention rate of 75% can be achieved.