氮杂环导电高分子改性锂离子电池石墨负极材料  

Surface-modification of graphite with N-heterocyclic conducting polymers as high performance anodes for Li-ion batteries

作　　者：王志勇 蔡君瑶 佘英奇 钟树林 潘康华 WANG Zhiyong;CAI Junyao;SHE Yingqi;ZHONG Shuin;PAN Kanghua(Hunan Zhongke Shinzoom Co.,Ltd,Changsha 410600,Hunan,China)

机构地区：[1]湖南中科星城石墨有限公司,湖南长沙410600

出　　处：《储能科学与技术》2024年第8期2511-2518,共8页Energy Storage Science and Technology

摘　　要：石墨负极是锂离子电池重要的负极材料,但其在锂离子电池应用过程中的低电导率、低倍率性能、低容量等问题限制了其进一步应用。表面包覆是石墨负极改性的重要方式,当前沥青包覆为常用的包覆方式,可以有效降低比表面积,但为了匹配新一代电池的应用场景,需优化改性方向。在本研究中,以商用石墨负极为主,使用氮杂环导电高分子作为包覆剂,在石墨表面进行原位包覆改性,得到了包覆石墨,并设置了梯度包覆量,经过一系列表征发现,氮杂环导电高分子包覆有效地提升了石墨负极的比容量与快充性能,并且容量随着包覆量的提升而进一步提升(石墨负极的锂电容量为352.3 mAh/g,包覆后的锂电容量最高可升至359.7 mAh/g)。在保持容量提升的同时,氮杂环导电高分子包覆也极大地提升了快充性能,通过优化的包覆量,将原始石墨的1.2C/0.05C容量保持率从39.22%提升至50.97%,在商用负极的容量和快充性能提升上实现了较大突破,并通过机理分析证明,氮杂环导电高分子在石墨表面进行原位包覆改性,为石墨提供了表层导电网络和额外的锂离子吸附位点,为石墨负极的容量和快充性能提升作出了较大贡献,可作为新一代负极材料表面改性的优化方向。Graphite is an important anode material for lithium-ion batteries(LIBs),but its shortcomings in conductivity,theoretical capacity,and rate performance limit its application in these systems.Surface coating is an effective strategy for optimizing the electrochemical properties of graphite in LIBs.Currently,surface coating is widely used for the modification of graphite by using pitch-based materials as coating precursors,which can reduce the specific surface area and polarization capacity loss.However,the strategy underlying anode modification must be optimized considering the applications of next-generation batteries.In this study,the in-situ surface coating modification of graphite is carried out by using an N-heterocyclic conductive polymer as a coating agent for a gradient coating.Upon investigating the coated graphite,it was found that the coating using the N-heterocyclic conductive polymer on the surface of graphite can effectively improve its specific capacity as the coating amount is increased(Gr:352.3 mAh/g;N-heterocyclic-coated graphite:359.7 mAh/g).Moreover,the fast charging performance of graphite was significantly enhanced after coating with the N-heterocyclic conductive polymer and optimizing the coating quantity(at 1.2 C/0.05 C,Gr:39.22%;N-heterocyclic-coated graphite:50.97%),achieving a significant breakthrough as commercial anodes considering the electrochemical performance of LIBs.The characterization and mechanism analyses indicate that the coating modification by the N-heterocyclic conductive polymer provides surface conductive network and additional lithium-ion adsorption sites for graphite.This greatly contributes to enhancing the specific capacity and fast charging performance of graphite,and it can be used as an effective method for the surface modification of next-generation anodes.

关 键 词：导电高分子 表面改性 石墨 锂离子电池 负极 

分 类 号：TM911[电气工程—电力电子与电力传动]