Semi-empirical long-term cycle life model coupled with an electrolyte depletion function for large-format graphite/LiFePO4 lithium-ion batteries

• Published in: Journal of power sources Vol. 365; pp. 257 - 265
• Main Authors: Park, Joonam, Appiah, Williams Agyei, Byun, Seoungwoo, Jin, Dahee, Ryou, Myung-Hyun, Lee, Yong Min
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2017
• Subjects: Electrolyte depletion; Large-format lithium-ion battery; Modeling and simulation; Semi-empirical cycle life model; Electrolyte depletion; Large-format lithium-ion battery; Modeling and simulation; Semi-empirical cycle life model
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.08.094

To overcome the limitation of simple empirical cycle life models based on only equivalent circuits, we attempt to couple a conventional empirical capacity loss model with Newman's porous composite electrode model, which contains both electrochemical reaction kinetics and material/charge balances. In addition, an electrolyte depletion function is newly introduced to simulate a sudden capacity drop at the end of cycling, which is frequently observed in real lithium-ion batteries (LIBs). When simulated electrochemical properties are compared with experimental data obtained with 20 Ah-level graphite/LiFePO4 LIB cells, our semi-empirical model is sufficiently accurate to predict a voltage profile having a low standard deviation of 0.0035 V, even at 5C. Additionally, our model can provide broad cycle life color maps under different c-rate and depth-of-discharge operating conditions. Thus, this semi-empirical model with an electrolyte depletion function will be a promising platform to predict long-term cycle lives of large-format LIB cells under various operating conditions. •Semi-empirical cycle life model with electrolyte depletion function is developed.•Our model is compared with a conventional semi-empirical model.•The broad cycle life color maps at various c-rate and DOD are offered.