Currently, the power battery box of pure electric vehicles is generally formed by stamping and welding 1.2 ~ 1.5mm steel plates. Its disadvantages are that the mechanical strength and stiffness of the structure are insufficient to meet the requirements of laws and regulations such as vibration, mechanical impact, drop, collision and extrusion. Vibration and noise reduction, electromagnetic radiation resistance and other functions are inadequate; Poor thermal conductivity and heat dissipation; Not conducive to lightweight. In particular, the continuous improvement of battery energy density ratio (that is, battery life) makes the application of steel structure battery box more and more limited. The new energy automobile industry seeks for new materials to meet the stringent technical and regulatory requirements of battery box, and it has become an inevitable development trend to improve the energy density ratio.