物理化学学报2019，Vol.35Issue(12)：1382-1390,9.DOI:10.3866/PKU.WHXB201903060
粘结剂对形貌各异的石墨负极电化学性能的影响
Effect of Binder Conformity on the Electrochemical Behavior of Graphite Anodes with Different Particle Shapes
摘要
Abstract
As an important component in electrodes,the choice of an appropriate binder is significant when fabricating lithium-ion batteries (LIBs) with good cycle stability and rate capability,which are used in numerous applications,especially portable electronics and eco-friendly electric vehicles (EVs).Semi-crystalline poly(vinylidene fluoride) (PVDF),which is a traditional and widely used binder,cannot efficiently accommodate the volume changes observed in the anode during the charge-discharge process while binding all the components in the electrode together,which results in increased internal cell resistance,detachment of the electrode components,and capacity fading.Herein,we have investigated a highly polar and elastomeric polyacrylonitrile-butadiene (NBR) rubber for use as a binder in LIBs,which can accommodate graphite particles of different shapes compared to semi-crystalline PVDF.Prior to our electrochemical tests,NBR was analyzed using thermogravimetric analysis (TGA) and X-ray diffraction (XRD),showing good thermal stability and an amorphous morphology.NBR is more conformable to irregular surfaces,which results in the formation of a homogeneous passivation layer on both spherical and flaky graphite particles to effectively suppress any electrolyte side reactions,further allowing more uniform and fast Li ion diffusion at the electrolyte/electrolyte interface.As a result,the electrochemical performance of both spherical and flaky shape graphite electrodes was significantly improved in terms of their first cycle Coulombic efficiency (CE) and cycle stability.With comparative specific capacity,the first cycle CE of the NBR-based spherical and flaky graphite electrodes were 87.0％ and 85.5％,compared to 85.3％ and 82.6％ observed for their corresponding PVDF-based electrodes,respectively.After 1000 discharge-charge cycles at 1C,the capacity retention of the NBR-based graphite electrodes was significantly higher than that of PVDF-based electrodes.This was attributed to the good stability of the solid electrolyte interphase (SEI) formed on the graphite electrodes and the high stretching ability of the elastomeric NBR binder,which help to accommodate the repeated volume fluctuation of graphite observed during long-term charge-discharge cycling.Electrochemical impedance spectroscopy (EIS) and microscopic analysis (SEM and TEM) were carried out to investigate the formation and evolution of the SEI layers formed on the spherical and flaky graphite electrodes.The results show that thin,homogeneous,and stable SEI layers are formed on the surface of both spherical and flaky graphite electrodes prepared using the NBR binder.When compared to the PVDF-based graphite electrodes,the graphite electrodes constructed using NBR showed decreased resistance in the SEI layer and faster charge transfer,thus enhancing the electrode kinetics for Li ion intercalation/deinteroalation.Our study shows that the electrochemical performance of spherical and flaky graphite electrodes prepared using the NBR binder is significantly improved,demonstrating that NBR is a promising binder for these electrodes in LIBs.关键词
粘结剂/聚丙烯腈-丁二烯/石墨负极/电化学性能/锂离子电池Key words
Binder/Polyacrylonitrile-butadiene/Graphite anode/Electrochemical performance/Lithium ion battery分类
化学化工引用本文复制引用
Rahim Shah,Naveed Alam,Amir A.Razzaq,杨成,陈宇杰,胡加鹏,赵晓辉,彭扬,邓昭..粘结剂对形貌各异的石墨负极电化学性能的影响[J].物理化学学报,2019,35(12):1382-1390,9.基金项目
The project was supported by the National Natural Science Foundation of China (21701118,21805201),the Natural Science Foundation of Jiangsu Province,China (BK20161209,BK20160323,BK20170341),the Postdoctoral Science Foundation of China (2017M611899,2018T110544) and the Key Technology Initiative of Suzhou Municipal Science and Technology Bureau,China (SYG201748).We extend our sincere appreciation to the support by Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies.国家自然科学基金(21701118,21805201),江苏省自然科学基金(BK20161209,BK20160323,BK20170341),中国博士后科学基金(2017M611899,2018T110544),苏州市产业技术创新专项(前瞻性应用研究)(SYG201748)资助项目 （21701118,21805201）
