摘要
采用交流阻抗谱(EIS谱)分析了不同预循环电压对富锂锰正极材料Li_(1.13)Mn_(0.54)Ni_(0.27)Al_(0.06)O_2表面固体电解质膜(SEI膜)性质的影响,并用高分辨透射电镜(TEM)观察了SEI膜的形态,用扫描透射电镜和能谱(STEM、EDS)分析其成分。交流阻抗分析结果表明:采用多步预循环,或者上截止电压在4.3~4.6 V的预循环制度可在正极材料表面得到低阻抗的、性能稳定的SEI膜;而直接充电到上截止电压4.8 V得到的SEI膜不稳定,循环后SEI膜阻抗和电荷转移阻抗都成倍增大;透射电镜观察到直接在2.0~4.8 V循环50次的正极材料表面包裹有较厚的有机物层和致密的无机物层;而多步预循环的正极材料颗粒表面仅有厚度5~15 nm的致密壳层。
The solid electrolyte interphase（SEI） layer of Li1.13Mn0.54Ni0.27Al0.06O2 cathode materials was analyzed by electrochemical impedance spectra（EIS）. The morphology of SEI layers was observed by transmission electron microscopy（TEM）. EIS data indicate that the pre-cycling potential significantly affect the impedance of SEI films.Those cells producing stable and low impedance SEI layer were pre-cycled between 4.3 and 4.6 V or under the step potential. In contrast, the RSEI and Rct of an un-precycled cell were doubled after 50 cycles. Organic and inorganic layer of SEI were observed on cathode particles that directly cycled. However, only a shell of 5 to 15 nm was formed on the surface of the step pre-cycled sample.
作者
伍小龙
邵威
郭玉忠
王剑华
WU Xiao-long;SHAO Wei;GUO Yu-zhong;WANG Jian-hua(College of Material Science and Engineering,Kunming University of Science and Technology,Kunming Yunnan 650093,China;Research Center for Analysis and Measure,Kunming University of Science and Technology,Kunming Yannan 650093,China)
出处
《电源技术》
CAS
CSCD
北大核心
2018年第6期774-777,902,共5页
Chinese Journal of Power Sources
基金
国家自然科学基金项目(51464025)
关键词
锂电池
SEI
交流阻抗谱
Li-ion batteries
SEI
impedance spectra
