The power battery is the core of an electric vehicle, and it must be able to withstand high temperatures, water, and freezing. When an electric vehicle becomes unable to move, the first thing to consider is a problem with the "core" (battery). But can the power battery withstand temperatures of 40 degrees Celsius in the high temperatures of summer?
How to dissipate heat from the power battery of an electric vehicle? Power batteries operate at high currents, generating significant heat. Simultaneously, the battery pack is in a relatively enclosed environment, leading to an increase in battery temperature. This is due to the electrolyte within the lithium battery; the electrolyte plays a crucial role in charge conduction, and a battery without an electrolyte cannot be charged or discharged.
Liquid thermal conductive silicone pads for water cooling pipes
Lithium-ion batteries are mostly composed of flammable and volatile non-aqueous electrolytes. This composition system has higher specific energy and voltage output compared to batteries with aqueous electrolytes, meeting users' higher energy demands. However, because non-aqueous electrolytes are themselves flammable and volatile, they permeate the inside of the battery and become a source of combustion.
Therefore, the operating temperature of both of the aforementioned battery materials must not exceed 60℃. However, the outdoor temperature is now close to 40℃, and the batteries themselves generate a lot of heat, which will cause the operating temperature of the batteries to rise. If thermal runaway occurs, the situation will be extremely dangerous. To avoid turning the batteries into "grills," heat dissipation is particularly important.
Power battery thermal conductive materials
There are two types of heat dissipation for power battery packs: active and passive, with significant differences in efficiency. Passive systems require lower costs and simpler measures. Active systems are more complex in structure and require greater additional power, but their thermal management is more effective. Different heat transfer media have different heat dissipation effects; air cooling and liquid cooling each have their advantages and disadvantages.
The main advantages of using gas (air) as the heat transfer medium are: simple structure, light weight, effective ventilation when harmful gases are generated, and low cost; the disadvantages are: low heat transfer coefficient between the gas and the battery wall, slow cooling rate, and low efficiency. It is currently widely used. The main advantages of using liquid as the heat transfer medium are:
Power battery thermal conductive silicone sheet
The high heat transfer coefficient between the battery and the battery wall results in rapid cooling; however, it also has drawbacks: high sealing requirements, relatively large weight, complex maintenance and repair, and the need for components such as water jackets and heat exchangers, leading to a relatively complex structure. In practical electric bus applications, due to the large capacity and volume of the battery packs, the power density is relatively low, thus air cooling is commonly used. For battery packs in ordinary passenger vehicles, the power density is much higher. Consequently, the heat dissipation requirements are also higher, making water cooling a more prevalent solution.
Different battery pack structures require different sensors depending on the temperature measurement points and requirements. Temperature sensors are placed in representative locations with significant temperature variations, such as air inlets/outlets and the central area of the battery pack. This is especially important in areas of high and low temperatures, and in the center of the battery pack where heat accumulates significantly. This helps maintain the battery temperature in a relatively safe environment, preventing overheating and overcooling from posing a danger to the battery.
