Structural design of aluminium alloy battery pack casing

After the rapid development in recent years, China has now become the world's number one country in terms of production and sales of new energy vehicles. With the introduction of the national subsidy policy for new energy vehicles in 2019 and the increase in range requirements, higher requirements for the energy density of the battery system have been put forward.

There are two paths to improve the energy density of the battery: one is to increase the specific energy of the single cell; the other is to lighten the structure of the battery pack. To increase the specific energy of a single cell is technically difficult, with long R&D cycles and large capital investment, while making the structure of the battery pack lighter is easier to achieve.

The use of aluminium alloys in automobiles has been commonplace for a long time. Aluminium has many advantages such as low density, high specific strength, thermal stability, corrosion resistance and good thermal conductivity, non-magnetic, easy to shape and high recycling value, making it an ideal material for lightweight battery pack design.

At present, the mainstream scheme for battery pack shell materials is extruded aluminium alloy shell + PP/glass fibre composite top cover.

From the point of view of current developments, the aluminium alloy shell and plastic top cover solution has the prospect of lightweighting. The aluminium extrusion profile + stir friction welding + MIG welding solution is used for the housing, which has a low overall application cost, meets the performance requirements and enables the integration of the circulating waterway for water-cooled batteries.

The top cover uses a non-metallic top cover, mainly using PP/glass fibre + LFT-D moulding process, which can improve the efficiency of production and also meet the requirements of flame burning and sealing performance, and the mould cost is low.
Aluminium alloy battery pack housings have been used in a number of new energy vehicles, such as the BYD Song and Tang, the Azera ES8 and the BAIC EV series. The housing can improve the energy density of the battery pack and increase the range. This shows that aluminium alloy battery pack shells have a broad market prospect.