【作者】 兰金叻； 刘远； 于运花； 杨小平；

【Author】 Jinle Lan;Yuan Liu;Yunhua Yu;Xiaoping Yang;College of Materials Science and Engineering,Beijing University of Chemical Technology;

【机构】 北京化工大学；

【摘要】 通过静电纺丝法与模板法分别制备了三种一维聚合物基碳质材料:聚丙烯腈（PAN）基碳纳米纤维、聚乙烯吡咯烷酮（PVP）基多孔碳纳米纤维以及聚多巴胺（PDA）基中空纳米碳管。首先,重点考察了氮元素掺杂含量以及其化学组成变化对于PAN基碳纳米纤维电化学性能的影响。研究发现,氮元素掺杂含量随碳化温度升高而降低,由12.5 at.%下降至2.8 at.%,其主要存在类型为吡啶氮、吡咯氮和石墨氮。其中,石墨氮含量越高,越有利于增加碳材料的导电性,从而有助于提高碳材料的倍率性能。随后,基于原位模板法,我们又制备了PVP基多孔碳纳米纤维,并考察了孔结构的引入对于材料储锂性能的影响。实验结果显示,中空状多孔结构有利于锂离子电解液浸润碳纳米纤维电极材料,并缩短锂离子的扩散距离,因而显著提高了PVP基碳纳米纤维的倍率性能。最后,基于上述两项研究结果,采用聚多巴胺为原料,制备了管壁超薄（¹6 nm）且具有开放型中空结构的氮掺杂碳管。数据结果显示,碳化温度为750℃时,碳管中石墨氮含量达到3.1 at.%。此时,碳管电极具有最优异的大电流充放电性能(在2 Ag^-1电流密度下,可逆比容量为406 mAh g^-1)。优异的倍率性能得益于高效的锂离子扩散界面以及良好的导电性。更多还原

【Abstract】 Three 1D polymer-derived amorphous carbons are prepared by electrospinning technique combined with SiO_x-template method in this section:polyacrylonitrile（PAN）-derived CNF,polyvinylpyrrolidone（PVP）-derived porous CNF,and Polydopamine（PDA）-derived N-doped carbon tube（N-CT）.At first,the effect of N-doping on the electrochemical performance of PAN-derived CNF is investigated.The results show that N element content dercease from 12.5 at.%to 2.8 at.%with the carbonization temperature increased.The N types in the CNF are divided into tpyridinic N,pyridonic N,and graphitic N,respectively.Among the three N types,graphitic N contributes to the improvement of electron conductivity of CNF,thus enhancing the rate performance of CNF.Then,we evaluate the PVP-derived porous CNF as the anode materials for LIBs.It is found that hollow-structural pore are more beneficial for the penetration of Li⁺-carrying electrode into the CNF,thus decreasing the Li⁺-diffusion distance,which leads to improved electrochemical performance,especially the rate performance.At last,based on the aforementioned two works,we employ PDA as the precursor to prepare N-CT with an ultra-thin wall thickness of about 16 nm.The results shows that the graphitic N content in N-CT（carbonization temperature is 750℃） is abundant（³.1%）.Benefiting from the synergistic effect of unique hollow structure and abundant N-doping that shorts the Li⁺-diffusion distance and facilitates the electron conductivity,the optimal N-CT electrode shows excellent rate performance(406 mA h g^-1 at 2 Ag^-1).更多还原