}
Credit: https://knaufautomotive.com/
Temperature control is one of the most important issue when using electric vehicle batteries. What many people do not realize is that temperature control is also one of the issues restricting fast charging of batteries.
Electric battery can only operate optimally in a a certain range of temperature, around 15 degree C 35 degree C . (see below)
Figure 1. Optimal Temperature from Evcreate.nl
Fast charging (or discharging) can cause temperature to increase. And high temperature can result in a phenomenon known as thermal runaway, meaning a vicious cycle of higher temperature causing a breakdown in battery chemistry, resulting in further deterioration and even higher temperature.
In the worst case scenario, thermal runaway can result in fire or explosions, hence effective thermal management solution is important.
There are currently two main method of EV battery thermal management : Air Cooling and Liquid Cooling.
Air Cooling
Air Cooling is by far the cheapest and more common method. As the name implies, air cooling relies on using air to dissipate the hear produced in the car battery. The vehicle will suck in air and direct the air to flow across heat sink connected to the battery, thereby helping to remove heat from the battery. A good example is the air cooling system used by Nissan Leaf.
Figure 2 Air Cooling example from Nissan Leaf. From Reddit article.
Liquid Cooling
Liquid Cooling relies on directing liquid to flow across the heatsink in contact with the batteries. Although having a much better heat transfer capability than air cooling system, its design is considerably more complex, and may require a customized battery pack design. The customized battery pack design may provide other advantages as well in the form of increased energy density. This mean the battery pack can fit more battery cells for the same amount of volume. Liquid cooling is currently used by established companies like Tesla and new liquid cooling battery pack concepts are constantly under development.
An interesting concept of a liquid cooling battery pack concept is the one developed by a Singapore start-up, Energeia Lab (EL). (see below)
Credit: El.sg