Lithium-ion batteries represent one the best chances for the next BEV and HEV generation [1]. Taking into account the actual lithium-ion technology, the safety and cost appear the main drawbacks holding the introduction of these storage systems into the automotive market. However, the current Li-ion battery manufacturing process has been greatly advancing in the last twenty years and those developments are also the basis for the production of large format cells demanded for automotive application.

The GREENLION consortium, a large scale collaborative project within the FP7 (GC.NMP.2011-1) [2] was aimed to tackle these issues, leading to the manufacturing of greener and cheaper lithium-ion batteries for electric vehicle applications via the use of water soluble, fluorine-free, high thermally stable binders, which would eliminate the use of organic compounds as solvent in the electrode coating process and reduce the cell assembly cost. The GREENLION project has identified three key levels in the value scale before the final battery pack integration for EVs, namely electrode processing, cell manufacturing and battery module assembly, which are the backbone of the lithium-ion battery production line.

Here, the performance and ageing robustness of 17 A h class, graphite/NMC stacked cells designed, developed and manufactured within GREENLION project, are reported. 

Results and Discussions

The cells exhibited analogous behavior in terms of charge/discharge features, displaying resistance below 5 m and nominal capacity equal or exceeding 17 A h at 23 °C (Figure 1). Slightly higher values, i.e., around 18 A h, are delivered at 45 °C whereas, at 0 °C, the cells are able to still deliver more than 80 % of their nominal capacity. 

Excellent cycling performance, reported in Figure 2, was exhibited, e.g., practically 100 % of the initial capacity was delivered after more than 500 full charge/discharge cycles run at 100 % DOD. 

The graphite/NMC stacked cells were subjected to prolonged ageing tests, carried out holding the GREENLION cells at 45 °C and monitoring their capacity every 4 weeks. The results, plotted in Figure 3 as capacity evolution recorded during storage tests, have revealed very remarkable robustness towards ageing phenomena. For instance, from 86 to 88 % of the initial capacity is retained upon 4 months. These characteristics, in combination with the excellent electrochemical performance, are clear indications of the good cell design and manufacturing of the GREENLION cells based on eco-friendly electrodes.

Acknowledgements

The authors wish to thank the financial support of the European Commission for the GREENLION project within the 7^thFramework Program (Grant agreement n°: 285268).

References

[1] B. Scrosati, J. Garche, J. Power Sources 195 (2010) 2419.

[2] O. Miguel, I. Cendoya, G.-T Kim, N. Löffler, N. Laszczynski, S. Passerini, P.M. Schweizer, F. Castiglione, A. Mele, G.B. Appetecchi, M. Moreno, M. Brandon, T. Kennedy, E. Mullane, K.M. Ryan, M. Olive, I. de Meatza, “GREENLION Project: Advanced Manufacturing Processes for Low Cost Greener Li-Ion Batteries” in Electric Vehicle Batteries: Moving from Research towards Innovation, Book ID 329226, Springer International Publishing Switzerland, 2014.