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This article proposes a novel methodology for the definition of an optimized immersion cooling fluid for lithium-ion battery applications aimed to minimize maximum temperature and temperature gradient during most critical battery operations. The battery electric behavior is predicted by a first order equivalent circuit model, whose parameters are experimentally determined. Thermal behavior is described by a nodal network, assigning to each node thermal characteristics. Hence, the electro-thermal model of a battery is coupled with a thermal management model of an immersion cooling circuit developed in MATLAB/Simulink. A first characterization of the physical properties of an optimal dielectric liquid is obtained by means of a design of experiment. The optimal values of density, thermal conductivity, kinematic viscosity, and specific heat are defined to minimize the maximum temperature and temperature gradient during a complete discharge of the battery at 2.5C.

Rising concern towards environment and decarbonization has increased the demand of EVs. However, one of the major challenges for these vehicles is to achieve the same driving ranges as that of ICEs. This can be attained by increasing the power of cells without altering their sizes; conversely, this has important effects on the cell thermal behaviour. The focus of this paper is to analyse the impact of changing the characterizing materials thicknesses of collectors and electrodes of a cylindrical cell on its thermal response and to determine an optimal configuration. The CFD software considered to conduct this research uses the equivalent circuit model (ECM) to represent a cell and requires material physical properties to calculate the thermal response. In the calculations presented, resistance, capacitance, and Open Circuit Voltage (OCV) needed for the ECM are obtained from experimental measurements.