Cooling performance and heat transfer from the Li-ion battery pack in electrical vehicles

Vehicles powered by internal combustion engines (ICEs) using fossil fuels are a major contributor to anthropogenic air pollution by releasing health high risk gases like SOx and NOx into the atmosphere. Electric vehicles (EVs), which have zero or very low road emissions and are gaining quick and widespread acceptance as a method of private and public transportation, are a clear and leading alternative to fossil fuel-powered ICE vehicles. Because of high-power storage to weight ratio and dependability, lithium-ion batteries have so far been given preference for usage in EVs. The longevity of these batteries, however, completely depends on how much heat is released throughout the charging and discharging cycles. In general, very high temperatures and/or large temperature nonuniformities in the battery pack will decrease the life of the batteries. In order to maximize battery life, the ideal thermal management system should be capable of maintaining the batteries within a specified temperature range, while minimizing batteries temperature nonuniformities in the pack. The thermal management strategy based on the temperature inside the cells (batteries), modules, and packs is described in this chapter, along with the relative benefits and drawbacks of various thermal cooling technologies. Techniques for battery thermal modeling and difficulties with cooling system design are also explored in this chapter. In addition, it is anticipated that future vehicles with high charge rates will need enhanced cooling systems, which will remove some of the limitations of the current cooling systems.