Computational Fluid Dynamics (CFD) analysis of Graphene Nanoplatelets for the cooling of a multiple tier Li-ion battery pack

Abstract

A customized Lithium Nickel Manganese Cobalt Oxide(NMC) based battery pack was designed using a Finite Element(FE) based model and simulated using a coolant containing 0.001 vol% and 0.005 vol% Graphene Nanoplatelets(GNPs) in a mixture of Ethylene Glycol(EG) and water (50:50) to assess the effectiveness in lowering the operating temperature within the battery pack. Three variations of the battery pack were simulated as one tier, two tier, and three tier systems to optimize the effectiveness and surface contact of the flowing coolant with the heated batteries. The pack's temperature was set to 60 °C, and a simulation study was run over a 15-second period of fluid flow to determine final temperature conditions. In comparison to pure EG/water fluid, operating temperature range was reduced by about 12% to 24% for 0.001 vol% GNP/EG/water fluid and 24% to 29% for 0.005 vol% GNP/EG/water fluid. The increased cooling capacity supplied by these coolant fluids are attributed to GNPs high thermal conductivity and larger surface area. From an initial temperature of 60 °C, the maximum temperature range for these designs was 42.250 °C to 45.760 °C, which was within the 45 °C recommended operational temperature range for Lithium-Ion Batteries(LIBs) used in Electric Vehicles(EVs). Suggested reasons for this have been, the presence of minor(0.001 vol% and 0.005 vol%) compositions of highly thermally conductive material as GNP, within the regular coolant fluid of EG/water and structural redesigning of the battery pack into two and three tier models, thereby, allowing a more uniform flow of the GNP/EG/water coolant, across the battery sections.