摘要
软碳是快充型锂离子电池的候选负极材料之一,发展高功率的软碳是当前的研究热点。软碳的电化学性能主要取决于其微观结构,并显著依赖前驱体的碳化温度。本工作以针状焦衍生软碳为模型材料,借助扫描电子显微(SEM)技术、X射线光电子能谱(XPS)、X射线衍射(XRD)、激光拉曼(Raman)光谱及氮气等温吸附等表征手段,追踪了其在900~1700℃碳化温度下的结构演化,并通过循环伏安(CV)、恒流充放电(GCPL)、交流阻抗(EIS)等电化学表征方法解析了其微观结构与储锂动力学的相关性。结果表明,随着碳化温度的提高,软碳会出现三个结构占优阶段(无定形结构、乱层结构、石墨化结构),并对其电化学行为产生显著影响。其中,在无定形结构占优区域,软碳孔隙发达,储锂动力学较快,但容量较小(195 mAh/g),库仑效率较低(<60%);在石墨化结构占优区域,软碳库仑效率较高(80%),但动力学缓慢;而在乱层结构占优阶段,软碳可获得最佳的微观结构,从而在可逆比容量、首次库仑效率和倍率性能之间取得平衡。该结果为合理设计高性能的快充型软碳负极材料提供了参考。
Soft carbon is one of the candidate materials for the fast-charging lithium-ion battery anode.Creating soft carbon with high power density is currently a research focus.Soft carbon's electrochemical properties are primarily determined by its microstructure,which is heavily influenced by the carbonization temperature of the precursor.The structural evolution of soft carbon derived from needle coke at a carbonization temperature of 900—1700℃was traced in this paper by varied characterizations of SEM,XPS,XRD,Raman,and N2 isothermal adsorption.Electrochemical characterizations of CV,GCPL,and EIS were also used to investigate the relationship between microstructure and lithium-storage kinetics.The results show that the carbonization temperature of soft carbon can be divided into three dominant steps based on the change of microstructures(amorphous,turbostratic and graphitic),which has a significant impact on the electrochemical properties of soft carbon.The soft carbon has abundant pores in the region dominated by amorphous structure,and the lithium-storage kinetics is fast,but the specific capacity(195 mAh/g)and the Coulomb efficiency(<60%)were low;The Coulombic efficiency is highest(80%)in the region dominated by graphitic structure,but the lithium-storage kinetics are significantly reduced;In the region dominated by turbostratic structure,the optimum microstructure can be obtained,which achieves a good balance between reversible capacity,coulomb efficiency and rate performance.This paper offers suggestions for the rational design of soft carbon for fast-charging lithium-ion batteries.
作者
王宇作
邓苗
王瑨
杨斌
卢颖莉
荆葛
阮殿波
WANG Yuzuo;DENG Miao;WANG Jin;YANG Bin;LU Yinli;JIN Ge;RUAN Dianbo(School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China;Ningbo CRRC New Energy Technology Co.,Ltd.,Ningbo 315112,Zhejiang,China;Unit 95979 of the PLA,Tai'an 271207,Shandong,China;Chengdu Baisige Technology Co.,Ltd.,Chengdu 610096,Sichuan,China;Ningbo Shunneng Technology Co.,Ltd.,Ningbo 315048,Zhejiang,China;Ningbo University,Advanced Research Institute for Energy Storage Technology and Equipment,Ningbo 315211,Zhejiang,China;School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China)
出处
《储能科学与技术》
CAS
CSCD
北大核心
2022年第6期1715-1724,共10页
Energy Storage Science and Technology
基金
轨道交通车辆制动能量回馈关键技术(2019B10045)。
关键词
锂离子电池
负极
软碳
动力学
碳化温度
lithium-ion battery
anode
soft carbon
kinetics
carbonization temperature
