Cylindrical Li-Ion Battery State of Health Evaluation by Differential Heat Analysis During Calendar Ageing
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CitationMurashko, K A. Mityakov, A, V. Mityakov, V Y. Sapozhnikov, S Z. Pyrhönen, J. Jokiniemi, J. (2019). Cylindrical Li-Ion Battery State of Health Evaluation by Differential Heat Analysis During Calendar Ageing. Journal of the electrochemical society, 166 (13) , A2896-A2902. 10.1149/2.0711913jes.
A novel method for the state of health (SoH) estimation and determination of the degradation mechanisms of cylindrical Li-ion cells after long storage time is presented. The proposed method is based on differential curves obtained with the help of temperature and heat flux measurements on the surface of a cylindrical lithium iron phosphate (LFP) cell. The applicability and advantages of the proposed differential curves for the SoH estimation and determination of degradation mechanisms are discussed and verified based on a comparison with currently existing in-situ diagnostic methods such as differential voltage (DV) analysis method. The results of the comparison show that the proposed differential curve can provide information about capacity fading and prevailing degradation mechanism at higher than 1 C-rate discharging current while the application of the DV curve may not be possible. Moreover, the presented method allows identification of the changes in the entropic heat generation, which may improve the SoH estimation and the determination of the degradation mechanisms in a cylindrical Li-ion cell after a storage period.