Effect of overcharge on Li(Ni0.5Mn0.3Co0.2)O2/Graphite lithium ion cells with poly(vinylidene fluoride) binder. I - Microstructural changes in the anode

JOURNAL OF POWER SOURCES

卷:385

Article

Rago, Nancy Dietz¹  Bareno, Javier¹  Li, Jianlin²  Du, Zhijia²  Wood, David L., III²  Steele, Leigh Anna³  Lamb, Joshua³  Spangler, Scott³  Grosso, Christopher³  Fenton, Kyle³  Bloom, Ira¹ 

[1] Argonne Natl Lab, Chem Sci & Engn Div, 9700 S Cass Ave, Argonne, IL 60439 USA

[2] Oak Ridge Natl Lab, Energy & Transportat Sci Div, Oak Ridge, TN 37831 USA

[3] Sandia Natl Labs, Power Sources Technol Grp, POB 5800, Albuquerque, NM 87185 USA

关键词: Lithium-ion battery;    Overcharge;    Scanning electron microscopy;    Microstructure;    SEI;    Anode;   

DOI  :  10.1016/j.jpowsour.2018.01.009

来源: Elsevier

【 摘 要 】

Cells based on NMC/graphite, containing poly(vinylidene difluoride) (PVDF) binders in the positive and negative electrodes, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state-of-charge (SOC). At 250% SOC the cell vented. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the anodes showed several state-of-overcharge-dependent trends. Starting at 120% SOC, dendrites appeared and increased in concentration as the SOC increased. Dendrite morphology appeared to be dependent on whether the active material was on the dull or shiny side of the copper collector. Significantly more delamination of the active material from the collector was seen on the shiny side of the collector particularly at 180 and 250% SOC. Transition metals were detected at 120% SOC and increased in concentration as the SOC increased. There was considerable spatial heterogeneity in the microstructures across each laminate with several regions displaying complex layered structures.

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