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

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

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1093 m^(2)·g^(-1)的高比表面积和0.63 cm^(3)·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1057.7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%。

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 1093 m^(2)·g^(-1) and pore volume of 0.63 cm^(3)·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 1057.7 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.