Three-dimensional layered electrochemical-thermal model for a lithium-ion pouch cell Part II. The effect of units number on the performance under adiabatic condition during the discharge

Recently, lithium-ion battery system appears to be an effective approach for energy storage due to their excellent performances. The internal structure of the lithium-ion pouch cell is laminated and is composed of several repeated units, and the unit includes five parts of positive current collector, positive electrode, separator, negative electrode and negative current collector. This structure brings great difficulties for simulator to develop full-scale model of the battery due to the complex calculation. In this paper, three kinds of three-dimensional layered electrochemical-thermal models with different unit numbers, one unit model (OUM), two unit model (TUM), and half-scale model (HSM) are established to study the effect of number of units on lithium-ion battery thermal behavior and electrochemical characteristics under adiabatic condition. The corresponding experimental procedure is performed for model validation, the simulation and experiment are in good agreement with temperature and discharge curves at four different discharge rates (0.5 C, 1 C, 1.5 C and 2 C). The results show that the temperature distribution and heat generation rate per volume as well as the representative electrochemical properties are almost the same of the three models; it is also found that each unit of the TUM and HSM is uniform and symmetrical distributed. Therefore, the HSM and full-scale model can be replaced by the OUM for lithium-ion pouch cell under adiabatic condition. The OUM can save 1/140 of computing time and greatly reduce the computational resources compared to HSM, which can facilitate the related research under adiabatic. (C) 2019 Elsevier Ltd. All rights reserved.