It is important to quickly categorise used batteries in order to determine their end-of-life, explore second-life applications and ensure safe storage and transportation. We have developed the database of battery ageing for such an analysis tool. Li-ion batteries were modified within and outside their specifications to induce possible ageing phenomena. EIS measurements were taken to follow their ageing process. Cells of the same type were taken from the recycling process. They were characterised in the same way. By comparing the results of the cells from normal use with the ageing phenomena in the battery ageing database, we have gained new insights into their unknown history. In addition, it is hoped that in the future the results of the EIS measurements from the analyser and the results from the battery ageing database can be used to predict the ageing effects within a used battery. For the battery ageing database, we have carried out characterisation of the structural and chemical changes from the macroscopic to the nanoscopic scale, starting with non-destructive techniques such as computed tomography (CT), followed by post-mortem analysis including light and electron microscopy (LM, SEM), focused ion beam SEM (FIB-SEM), energy dispersive X-ray analysis (EDS) and mass spectrometry (SIMS). This database is

o supplemented with further ageing effects and experimental results found in the literature
o contains the relationship of the cause to ageing phenomena and their effects (adapted to [1-3])
o is divided into three sections with their ageing phenomena:

• Cathode side: Particle cracking, phase transformation of active material, loss of transition metals, surface coatings CEI (cathode electrolyte interface), changes in the conductive additives
• Anode-side: SEI formation and alteration, Li-plating, electrolyte decomposition, Cu corrosion, particle cracking, binder decomposition
• Inactive components: Separator changes, triggered current interruption device (CID), Jelly Roll deformation, Battery housing deformation & corrosion, current collector deformation

o Each ageing phenomenon is briefly described and illustrated with the characterisation results

Some results of the CT investigations are summarised in the 1st appendix. The second appendix shows studies of an overcharged cell outside specification, scanning electron microscopy images and element distribution images obtained by energy-dispersive X-ray spectroscopy (EDS). [4]

[1] Vetter, J.; Novák, P.; Wagner, M. R.; Veit, C.; Möller, K.-C.; Besenhard, J. O. et al. (2005) Ageing mechanisms in lithium-ion batteries. In: Journal of Power Sources 147 (1-2), S. 269–281, doi: 10.1016/j.jpowsour.2005.01.006
[2] Birkl, Christoph R.; Roberts, Matthew R.; McTurk,Euan; Bruce, Peter G.; Howey, David A. (2017)
Degradation diagnostics for lithium ion cells, Journal of Power Sources, Volume 341, 2017, Pages 373-386, doi.org/10.1016/j.jpowsour.2016.12.011.
[3] Woody, M.; Arbabzadeh, M.; Lewis, G. M.; Keoleian G. A. und Stefanopoulou A. (2020) „Strategies to limit degradation and maximize Li-ion battery service lifetime – Critical review and guidance for stakeholders,“ Journal of Energy Storage, Jg. 28, S. 101231, doi: 10.1016/j.est.2020.101231
[4] We acknowledge the German BMBF (FKZ:03XP0317A) and BMWK (FKZ:16BZF320C) for financial support.