Degradation mechanisms of C6/LiNi0.5Mn0.3Co0.2O2 Li-ion batteries unraveled by non-destructive and post-mortem methods

JOURNAL OF POWER SOURCES

卷:416

Article

Li, Dongjiang^1,2  Li, Hu¹  Danilov, Dmitri L.^2,3  Gao, Lu³  Chen, Xiaoxuan¹  Zhang, Zhongru¹  Zhou, Jiang⁴  Eichel, Ruediger-A.^2,5  Yang, Yong¹  Notten, Peter H. L.^2,3,6 

[1] Xiamen Univ, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China

[2] Forschungszentrum Julich, Fundamental Electrochem IEK 9, D-52425 Julich, Germany

[3] Eindhoven Univ Technol, NL-5600 MB Eindhoven, Netherlands

[4] Tianjin Lishen Battery Joint Stock Co Ltd, Tianjin 300384, Peoples R China

[5] Rhein Westfal TH Aachen, D-52074 Aachen, Germany

[6] Univ Technol Sydney, Sydney, NSW 2007, Australia

关键词: Li-ion battery;    Solid-electrolyte-interphase;    Irreversible capacity loss;    Electromotive force;    Electrode degradation;   

DOI  :  10.1016/j.jpowsour.2019.01.083

来源: Elsevier

【 摘 要 】

The ageing mechanisms of C-6/LiNi0.5Mn0.3Co0.2O2 batteries at various discharging currents and temperatures have systematically been investigated with electrochemical and post-mortem analyses. The irreversible capacity losses MO at various ageing conditions are calculated on the basis of regularly determined electromotive force (EMF) curves. Two stages can be distinguished for the degradation of the storage capacity at 30 degrees C. The first stage includes SEI formation, cathode dissolution, etc. The second stage is related to battery polarization. The various degradation mechanisms of the individual electrodes have been distinguished by dV(EMF)/ dQ vs Q(out) and dV(EMF)/ dQ vs V plots. The Solid-Electrolyte-Interface (SEI) formation as well as the electrode degradation has been experimentally confirmed by XPS analyses. Both Ni and Mn elements are detected at the anode while Co is absent, indicating that the bonding of Co atoms is more robust in the cathode host structure. A Cathode -Electrolyte Interface (CEI) layer is also detected at the cathode surface. The composition of the CEI layer includes Li salts, such as LiF, LiCOOR, as well as transition metal compounds like NiF2. Cathode dissolution is considered to be responsible for both the NiF2 detected at the cathode and Ni at the anode.

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