The Battery Show Europe 2019: Thermal management technology of Lithium-ion batteries

A showcase of advanced battery and Hybrid/EV technology, and solutions to cool the battery cells

2019/07/04

Summary

  Jointly "The Battery Show Europe" and the "Electric & Hybrid Vehicle Technology Expo" were held from May 7 through May 9, 2019 in Stuttgart, Germany. These three days of exhibition and conference focused on one side on advanced battery technology from manufacturers and service providers capturing the battery systems, its components, the testing and finally recycling. On the other side stood the application of innovative solutions - electrical powertrains, battery management systems, materials and also equipment for hybrid and full electric passenger cars and commercial vehicles.

  While in the initial stages of electro mobility nickel metal hydride (NiMH) batteries had been used, the market changed fast towards lithium-ion (Li-ion) batteries for the same reasons which made it the solution of choice for mobile electronics like smartphones, tablets or laptops: high energy density (Wh/kg) and nearly no memory effect. One key challenge in automotive applications is however the thermal management of the Li-ion batteries under all operational and climatic conditions.

Keihin cooling system
Keihin cooling system
(The Battery Show Europe 2019, photographed by reporter)

  The focus of this report is on the thermal management of temperature sensitive Lithium-ion batteries in automotive applications to enable maximum performance and durability. Different solutions to cool the battery cells (and some also with the potential to heat at low ambient temperatures) are depending on customer requirements, cell types, installation space and duty cycles of the battery modules. Key for performance and battery life is the extraction of heat evenly from all cells of a battery pack or module. Heat can reach the cells from the outside but mainly it is generated inside the cells at high charge/discharge currents.

 The coolant of a combustion engine reaches ~90°C, the so-called low-temperature coolant circuit for electric drives and power electronics reaches ~60°C. Both coolants are too hot for lithium-ion battery cells which ideally should operate in the range of approximately 10°C to 35°C. Therefore different measures are in the market or under development to keep Li-ion cells below 35°C to prevent loss of performance and irreversible aging. Both effects occur also at low temperatures where heating of the cells may be required.

  First automotive Li-ion battery applications had no thermal management at all or used air cooling. State-of-the-art are nowadays actively cooled battery systems where the battery thermal management is integrated with the vehicle thermal management system and it's refrigerant climate system. Until new battery types with less temperature sensitive chemistries are coming to the market - mass production solid-state batteries are expected by industry experts around 2030 - a form of thermal management will be necessary.

 

Related reports:
Next-generation batteries options: storage battery technologies for automotive applications (Apr. 2019)
EV and FCV Components exhibited during World Smart Energy Week 2019 (Mar. 2019)
Tesla Model 3 Teardown: Motor, Inverter, and Battery (Mar. 2019)
Nissan LEAF Teardown: Lithium-ion battery pack structure (Dec. 2018)