Application of thermal management materials for power batteries in new energy vehicles
Thermal management of power batteries is a key technology in the field of lithium-ion batteries. Its main purpose is to ensure that the temperature of the battery is within a safe range during use and charging, while improving the energy density and service life of the battery. Thermal management materials are an indispensable technical support to achieve this goal. Next, I will introduce you to the application and analysis of thermal management materials for power batteries.
1. Thermal Conductive Materials
Heat conduction is the most basic problem in thermal management of power batteries, and thermal conductive materials play a key role in this process. At present, there are two main types of thermal conductive materials used in power batteries: thermal conductive paste and thermal conductive sheet.
Thermal conductive paste is a thermal conductive material that transfers heat from high temperature to low temperature, and is often used on the contact surface between the battery and the radiator. The thermal conductivity of thermal conductive paste is usually between 1-8 W/mK. Thermal conductive paste can be prepared using diamond particles, silicon nitride and other thermal conductive particles as carriers. Since thermal conductive paste can fill tiny gaps and cracks, it has been widely used in the thermal management of power batteries.
Thermal conductive sheet is a material that transfers heat evenly from the surface of the battery to the nearby radiator. Thermal conductive sheets are usually made of copper or aluminum, and their thermal conductivity is about 200 W/mK. The use of thermal conductive sheets can make the radiator and battery surface more evenly cooled, and improve the adsorption of the radiator to the battery to prevent it from falling off under vibration.
2. Thermal barrier material
Thermal barrier material is a material that can slow down the flow of heat. It is often used inside battery modules and installed between battery cells and radiators to reduce temperature gradients, lower battery surface temperatures, and increase battery safety. The thermal conductivity of thermal insulation materials is usually between 0.2-0.35 W/mK and is easy to process and form.
There are two main types of thermal barrier materials: insulating thermal insulation materials and composite thermal insulation materials. Insulating thermal insulation materials are mainly used to reduce the surface temperature of batteries and are installed between battery cells and radiators. Their main raw materials include glass fiber, ceramics, etc. Composite thermal insulation materials are a combination of multiple performance materials, such as nano-silicon dioxide and polymers. They prevent the conduction of heat and current, and have high strength and durability, so they are widely used.
3. Phase change material
Phase change material is a substance that can absorb and release a large amount of heat energy, which makes it widely used in power battery thermal management. The use of phase change material can reduce the peak surface temperature of the battery during charging and discharging, thereby improving the battery life. This is because the melting point of phase change material is usually very stable, so when charging or discharging reaches a certain temperature, the phase change material will absorb a large amount of heat energy, thereby maintaining the stable state of the battery surface temperature.
At present, phase change materials are mainly divided into two types: organic phase change material and inorganic phase change material. Organic phase change material is mainly used in low temperature range and has a high degree of purity, but the absorption and release of heat is relatively slow. Inorganic phase change material absorbs and releases heat faster, but the problems of easy melting at high temperature and toxicity also limit its application range.
