Abstract
The mechanical behavior of high capacity (1.4Ah) multilayer Si alloy-Graphite/NMC622 pouch cells under an external compressive load is presented in this research. The results show that their mechanical behavior is more complex compared to traditional cells with graphite anodes. Three distinct mechanisms are identified in the pressure evolution: i) a reversible pressure variation related to the lithiation of the anode, ii) an irreversible relaxation that occurs during early cycles and iii) an irreversible pressure growth related to capacity degradation. All mechanisms are investigated separately and a root cause is proposed for each one. Cells are cycled at different conditions to study the effect of initial compressive load, ambient temperature, current rate and depth of discharge on the mechanical behavior. Finally, a modeling methodology is proposed to estimate cell capacity fade based on cell pressure measurements and to model the expected pressure evolution during cycling. Presumably, this pressure behavior will become a key factor in designing future battery modules and packs containing energy-dense, volume changing electrode materials such as Silicon.
| Original language | English |
|---|---|
| Article number | 227774 |
| Number of pages | 11 |
| Journal | Journal of Power Sources |
| Volume | 451 |
| DOIs | |
| Publication status | Published - 1 Mar 2020 |
Bibliographical note
Funding Information:The next-generation full Li-ion pouch cell investigated in this research is the third generation of cells developed during the European FiveVB project, 1 1 funded by the Horizon 2020 research and innovation program of the European Commission. The cells consist of innovative prototype electrode materials: the cathode is a combination of NMC622 active material (Umicore) and PVdF HSV1800 binder (Arkema). The anode consists of 55 wt% Si-alloy (3 M) combined with 33 wt% SMG-A3 graphite (Hitachi). The electrolyte is composed of 1 M LiPF6 and 0.1 M Lifetime Electrolyte Arkema (LEA) in EC:EMC 3:7 (V/V) combined with 10% fluorethylene carbonate (FEC). The consolidation of these next generation materials results in a cell with a useful voltage window of 2.7 V–4.4 V, a nominal capacity of 1360 mAh and a high specific energy of 205 Wh.kg −1 . The full summary of cell specifications is presented in Table 1 . More detailed information on the cell manufacturing process can be retrieved in Ref. [ 27 ].
Funding Information:
This research was funded by the European Union's Horizon 2020 research and innovation program under grant agreement No 653531 . We acknowledge Flanders Make for the support to our research group MOBI.
Publisher Copyright:
© 2020 Elsevier B.V.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.