The power battery system (battery pack) is the core energy source that provides driving power for new energy vehicles, and is one of the most critical components of new energy vehicles. The power battery system is mainly composed of battery modules, electrical systems, thermal management systems, battery pack shells, and BMS. The battery modules, electrical systems, thermal management systems, and BMS are packaged through the shell to form the main body of the power battery system.
The main function of the battery pack shell is to carry the battery pack, electrical module, cooling module and other power battery system components, while protecting the battery and electrical system from damage when the vehicle is subjected to external collisions, impacts and extrusions. Traditional metal materials such as steel plates, aluminum plates, extruded aluminum profiles, and die-casting aluminum are used in battery casings of different models.
1. Steel shell
Steel battery pack casing is the most primitive power battery pack casing material, which is generally welded by cast steel plates. High strength, high rigidity, heavy quality, the surface needs anti-corrosion treatment, so that it still has a good anti-corrosion effect under long-term high temperature conditions.
2. Aluminum housing
The automobile power battery pack is made of aluminum material, which has the characteristics of easy processing, high temperature corrosion resistance, good heat transfer and electrical conductivity, long service life, flame retardant, anti-aging performance, and explosion-proof performance. Three different types of aluminum, rolled aluminum plate, extruded aluminum profile, and cast aluminum, have been applied in batches in different battery pack casing projects, and have become the mainstream technical route for power battery system casings.
3. SMC composite material
Sheet molding compound, the main raw material is composed of GF (special yarn), UP (unsaturated resin), low shrinkage additive, MD (filler) and various auxiliaries. SMC has good electrical properties, chemical corrosion resistance, low thermal conductivity, small expansion coefficient, excellent UV resistance and anti-aging properties, good fatigue resistance, light weight and high strength. It has also been used in the manufacture of battery pack casings.
4. Carbon fiber reinforced composites
Carbon fiber composite materials have become an ideal substitute for traditional metal battery pack casings. Compared with metal materials, the density of carbon fiber is about 1.7g/cm³. Tensile strength 3000MPa, elastic modulus 230GPa, light weight and high strength, high temperature resistance, friction resistance, shock resistance, low thermal expansion coefficient.
5. PC+LFT-D long fiber reinforced thermoplastic material
The excellent flame retardant properties, dimensional stability and mechanical properties of PC materials complement the inherent long fiber retention rate of the LFT-D process and perfectly meet the needs of battery pack casing applications. The material has the characteristics of good flame retardancy, high rigidity, high toughness, and the parts are not easy to crack. The upper and lower shells can be combined more closely, which improves the air tightness level of the battery pack during long-term use.
Under the leadership of the rapid development of new energy vehicles in my country, electrification has become the main trend of global automobile development. As a new energy power system component, the power battery case will rapidly increase the market size of the battery case.