Lithium ion battery (LIB) degradation originates from complex mechanisms, usually interacting simultaneously in various degrees of intensity. Due to its complexity, to date, identifying battery aging mechanisms remains challenging. Recent improvements in battery degradation identification have been developed, including validated, in-situ incremental capacity (IC) and peak area (PA) analysis. Due to their in-situ and non-destructive nature, IC and PA implementation is feasible in on-board battery management systems (BMS). Despite their advantages, the understanding and applicability of IC and PA techniques is not straightforward, as it requires both electrochemical and material science backgrounds. However, BMS design teams are mainly integrated by electrical engineers and may not include battery scientists. Aiming to bridge gaps in knowledge between electrical engineering and battery science towards battery degradation identification, here we present a systematic approach consisting in a set of look-up tables generated from IC and PA techniques. The look-up tables provide a simple, yet reliable tool for the evaluation of LIB degradation modes. Various real-life examples of cell degradation are also presented to illustrate and validate the use of the proposed approach. This study exemplifies the use of look-up tables providing a simple, fast, and accurate automated estimation of LIB degradation modes to be implemented in BMSs.
The cell case temperature versus time profiles of a multistage fast charging technique (4C-1C-constant voltage (CV))/fast discharge (4C) in a 2.3 Ah cylindrical lithium-ion cell are analyzed using a thermal model. Heat generation is dominated by the irreversible component associated with cell overpotential, although evidence of the reversible component is also observed, associated with the heat related to entropy from the electrode reactions. The final charging stages (i.e., 1C-CV) significantly reduce heat generation and cell temperature during charge, resulting in a thermally safe charging protocol. Cell heat capacity was determined from cell-specific heats and the cell materials’ thickness. The model adjustment of the experimental data during the 2 min resting period between discharge and charge allowed us to calculate both the time constant of the relaxation process and the cell thermal resistance. The obtained values of these thermal parameters used in the proposed model are almost equal to those found in the literature for the same cell model, which suggests that the proposed model is suitable for its implementation in thermal management systems.
The cell case temperature versus time profiles of a multistage fast charging technique (4C-1C-CV)/fast discharge (4C) in a 2.3 Ah cylindrical lithium-ion cell are analyzed using a 1D thermal model. Heat generation is dominated by the irreversible component associated to cell overpotential, although evidences of the reversible component are also observed, associated to the heat related to entropy from the electrode reactions. The final charging stages (i.e., 1C-CV) significantly reduce heat generation and cell temperature during charge, resulting in a thermally safe charging protocol. Cell heat capacity was determined from cell specific heats and cell materials thickness. The 1D model adjustment of the experimental data during the 2 min. resting period between discharge and charge allowed us to calculate both the time constant of the relaxation process and the cell thermal resistance. The obtained values of these thermal parameters used in the proposed model are almost equal to those found in the literature for the same cell model, which suggests that the proposed model is suitable for its implementation in thermal management systems.