Reproducibility of Li-ion cell reassembling processes and their influence on coin cell aging

• Published in: Journal of energy storage 2019-08, Vol.24, p.100732, Article 100732
• Main Authors: Schmid, Alexander Uwe, Kurka, Moritz, Birke, Kai Peter
• Format: Article
• Language: English
• Subjects: Aging; Coin cells; Li-ion; Reassembly
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2019.04.006

•Developing of a reassembly method to investigate industrially produced Li-ion cells.•The reassembled coin cells show low cell-to-cell variations and stable cycle aging.•The choice of the separator is crucial for building coin cells.•Minor influence of washing the electrodes with DMC on capacity retention.•Washing the electrodes increases the resistance of the coin cells. Extracting coin cells from industrially manufactured Li-ion cells is a commonly used method to investigate the state-of-health of the electrode material. However, the influence of the reassembling process on coin cell performance and its reproducibility is not clearly described in the literature. For this intention, we develop a preparation procedure to extract the cell material out of these original cells and build coin cells. The measurements of the reassembled Li-ion coin cells reveal a similar relative standard deviation in capacity to commercially cells at begin of life. Furthermore, the coin cells show a stable aging behavior with a mean capacity loss of about 5% after 300 full cycles at 25 °C. The washing of the electrodes before the reassembly does not decrease the relative standard deviation in capacity at begin of life and during the cyclic aging. The relative standard deviation in impedance is larger for the washed coin cells. In addition, we analyze the influence of the separator on the aging of the coin cells. Coin cells with a double-layer separator, consisting of polypropylene fiber and a polyethylene membrane, show a lower variation in capacity at begin of life and a lower loss in capacity over cycle aging than coin cells with the separator from the original cell.