工程科学学报，第40卷，第6期：729-734,2018年6月 Chinese Journal of Engineering,Vol.40,No.6:729-734,June 2018 D0I:10.13374/j.issn2095-9389.2018.06.011:htp:/journals..usth.edu.cn 锂离子电芯用电极对温度与S0C的敏感性 安富强，周伟男，李平四 北京科技大学新材料技术研究院，北京100083 ☒通倍作者，E-mail:liping(@usth.cdu.cn 摘要采用阻抗谱技术，对2.8Ah18650电芯进行拆解解析，单独分析正负极电极在不同温度下(25、10和-5℃)，不同荷 电状态下的阻抗变化.结果表明：在不同温度下，在20%~100%荷电状态下，负极作为控制电极，其反应电化学阻抗是正极的 数倍，尤其是在-5℃，达到了4倍，负极是电芯一致性问题中动力学因素的控制主因：在0~20%荷电状态下，在10和25℃ 下，正极的反应电化学阻抗要远远大于负极，正极成为控制端.结合目前电动车上动力电池的实用荷电状态一般在20%~ 95%,针对该2.8Ah18650电芯，提高负极电极的一致性是核心所在.同理，对其他类型电芯而言，在电芯设计过程中，在综 合考虑成本的前提下，需要更有针对性地提高正负极的一致性标准，从而更为有效地改善整个电芯产品的一致性. 关键词18650电芯：荷电状态(S0C):一致性：电极：阻抗谱 分类号U469.7 Sensitivity of electrodes in a lithium ion cell to temperature and SOC AN Fu-qiang,ZHOU Wei-nan,LI Ping Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail:liping@ustb.edu.cn ABSTRACT In the design and development of electric vehicles (EVs),the variation in lithium ion cells (LICs)is one of the most important safety issues as it can cause a decrease in the life of the battery systems and shorten the mileage range.This problem is rooted in the design accuracy and rationality of the process values for the battery electrodes,and defining the effects of temperature and state of charge (SOC)on the electrodes is a critical step toward improving the variation in LICs.In this paper,the electrochemical imped- ance spectroscopy (EIS)method was adopted to study the 2.8A.h 18650 cell.Firstly,the cells was dissembled and then attached the positive/negative electrodes separately to coin cells with an Li plate as the count electrode.Secondly,the impedance changes at differ- ent temperatures (25,10 and-5C)and the SOCs for these coin cells were studied using EIS.The results show that for 20%-100% state of charge at different temperatures,the negative electrode is the control electrode;electrochemical impedance is several times that of the positive electrode,especially,at-5C,it reaches 4 times.Therefore,the negative electrode is the control factor in the kinetic variation process.For 020%SOC at 25 and 10C,the electrochemical impedance of the positive electrode is larger than that of the negative electrode and it becomes the control electrode.Regarding EVs:1)the normal SOC usage range is 20%95%;and 2)the working temperature range is above OC to satisfy cell variations in the pack and benefit the life of the cells.Combined with the above results,it can be concluded that improving the variation in the negative electrodes is most useful to the variation in the 2.8A.h 18650 cell.Above all,in the design process for LICs,the variation of electrodes should be improved as a target for improving costs and yields. KEY WORDS 18650 cell:state of charge (SOC):variation:electrode:electrochemical impedance spectroscopy 收稿日期：2017-10-31 基金项目：国家自然科学基金资助项目(51172024)工程科学学报，第 40 卷，第 6 期: 729--734，2018 年 6 月 Chinese Journal of Engineering，Vol． 40，No． 6: 729--734，June 2018 DOI: 10． 13374 /j． issn2095--9389． 2018． 06． 011; http: / /journals． ustb． edu． cn 锂离子电芯用电极对温度与 SOC 的敏感性 安富强，周伟男，李 平 北京科技大学新材料技术研究院，北京 100083 通信作者，E-mail: liping@ ustb． edu． cn 摘 要 采用阻抗谱技术，对 2. 8 A·h 18650 电芯进行拆解解析，单独分析正负极电极在不同温度下( 25、10 和 － 5 ℃ ) ，不同荷 电状态下的阻抗变化． 结果表明: 在不同温度下，在 20% ～ 100% 荷电状态下，负极作为控制电极，其反应电化学阻抗是正极的 数倍，尤其是在 － 5 ℃，达到了 4 倍，负极是电芯一致性问题中动力学因素的控制主因; 在 0 ～ 20% 荷电状态下，在 10 和 25 ℃ 下，正极的反应电化学阻抗要远远大于负极，正极成为控制端． 结合目前电动车上动力电池的实用荷电状态一般在 20% ～ 95% ，针对该 2. 8 A·h 18650 电芯，提高负极电极的一致性是核心所在． 同理，对其他类型电芯而言，在电芯设计过程中，在综 合考虑成本的前提下，需要更有针对性地提高正负极的一致性标准，从而更为有效地改善整个电芯产品的一致性． 关键词 18650 电芯; 荷电状态( SOC) ; 一致性; 电极; 阻抗谱 分类号 U469. 7 收稿日期: 2017--10--31 基金项目: 国家自然科学基金资助项目( 51172024) Sensitivity of electrodes in a lithium ion cell to temperature and SOC AN Fu-qiang，ZHOU Wei-nan，LI Ping Institute for Advanced Materials and Technology，University of Science and Technology Beijing，Beijing 100083，China  Corresponding author，E-mail: liping@ ustb． edu． cn ABSTＲACT In the design and development of electric vehicles ( EVs) ，the variation in lithium ion cells ( LICs) is one of the most important safety issues as it can cause a decrease in the life of the battery systems and shorten the mileage range． This problem is rooted in the design accuracy and rationality of the process values for the battery electrodes，and defining the effects of temperature and state of charge ( SOC) on the electrodes is a critical step toward improving the variation in LICs． In this paper，the electrochemical imped￾ance spectroscopy ( EIS) method was adopted to study the 2. 8 A·h 18650 cell． Firstly，the cells was dissembled and then attached the positive / negative electrodes separately to coin cells with an Li plate as the count electrode． Secondly，the impedance changes at differ￾ent temperatures ( 25，10 and － 5 ℃ ) and the SOCs for these coin cells were studied using EIS． The results show that for 20% --100% state of charge at different temperatures，the negative electrode is the control electrode; electrochemical impedance is several times that of the positive electrode，especially，at － 5 ℃，it reaches 4 times． Therefore，the negative electrode is the control factor in the kinetic variation process． For 0--20% SOC at 25 and 10 ℃，the electrochemical impedance of the positive electrode is larger than that of the negative electrode and it becomes the control electrode． Ｒegarding EVs: 1) the normal SOC usage range is 20% --95% ; and 2) the working temperature range is above 0 ℃ to satisfy cell variations in the pack and benefit the life of the cells． Combined with the above results，it can be concluded that improving the variation in the negative electrodes is most useful to the variation in the 2. 8 A·h 18650 cell． Above all，in the design process for LICs，the variation of electrodes should be improved as a target for improving costs and yields． KEY WOＲDS 18650 cell; state of charge ( SOC) ; variation; electrode; electrochemical impedance spectroscopy