1) Special welding method  Industrial traditional copper GB/T 2059-2008 aluminum GB/T 3190-1996  connection process Alloy high conductivity

In order to reduce corrosion and aging as much as possible, from different angles of technology and materials, industry has adopted a variety of welding methods such as pressure welding, fusion welding and brazing. Because it can not meet the requirements of high strength, high corrosion resistance, low cost and simple process at the same time, the existing fusion welding, pressure welding and brazing processes of copper and aluminum still need to be further improved, among which the brazing process is more promising.

The atoms in the solder layer diffuse to both sides of copper and aluminum to prevent the direct contact of copper and aluminum atoms. The diffusion of solder can prevent the diffusion of copper and aluminum atoms, so as to avoid the reaction of primary battery. As an intermediate metal, Ni is the most commonly used one.

In the connection of power battery, especially for the strong current part, the conductive parts are seldom welded together directly, but the finished products produced by copper aluminum welding are used as the bonding conductive parts, such as copper aluminum joints, copper aluminum connecting pieces, etc., as shown in the following figure.

2) Use of intermediate metal transition layer

Throughout the conductive metals, only tin and silver have stable electrochemical properties, and the price of tin is relatively cheap. It has been found through trial that the transition connection of copper tin aluminum can make the circuit conduct electricity more smoothly and safely, and the method is simple: first wrap the aluminum wire with tin paper, tie it with copper wire, and then connect it with copper wire according to the conventional connection method. In this way, the conductor (line) connected by copper and aluminum can run safely for a long time.

3) Copper aluminum composite

To avoid overlapping of copper and aluminum, but also want to use the low price and low density, another solution of conductive parts is to pack copper skin on the aluminum strip. Bimetal composite with aluminum as matrix and copper as outer layer. Through the special technology, the permanent metallurgical combination material between aluminum core and copper tube is formed. The surface of the product is bright, round and flawless, and can be processed to meet the use requirements. It is a new material combining high-quality and stable conductivity of copper with relatively stable, low-cost and low-density of aluminum. It has low contact resistance, and the current carrying capacity is more than 85% of the pure copper bar. It can comprehensively replace the pure copper bar. In the copper-clad aluminum bar, copper accounts for 40% of the total, and aluminum accounts for 60% of the total. It is 2.5 times longer than the pure copper bar under the same specification. The current carrying capacity is close to T2 pure copper bar, and it is slightly larger The specifications of the points can completely meet the same carrying capacity, and meet the technical requirements of the wire diameter, mechanical and electrical properties required by customers.

The density of copper-clad aluminum bars is only 37% - 40% of that of pure copper bars, and the length (volume) of the same weight is 2.5-2.7 times of that of pure copper bars. After special heat treatment process, the copper-clad aluminum bar has certain plasticity, which is conducive to punching, shearing and bending products without cracking and separation. In order to improve the corrosion resistance, tin plating and zinc plating can be carried out on the surface of copper layer. Copper clad aluminum has good ductility and reliability. Copper clad aluminum bar can be used to replace copper bar and aluminum bar.

Originally, according to the skin effect of communication, this method has better application effect in the AC system. There is a comparative data of copper and aluminum under the application conditions of automation, metallurgy, high and low voltage electrical appliances, construction industry, etc. the data is very good, which is worthy of our research and trial in the power battery system. The electrical performance comparison of copper bus TMY, aluminum bus lmy and copper aluminum composite bus tlmy is as follows:

How long can the power car battery pack outlet connector last? We don't have specific case support. We can only evaluate its performance through aging test. For example, through dry heat test, 1000 hours, 2000 hours, to test its front and back temperature, whether the product is easy to heat up, and whether it exceeds the international general standard.

Bexel, a battery pack manufacturer in South Korea, has shipped 1 million battery packs in a row. It uses the outlet connector of the battery pack of the power car. The market reaction effect is obvious and the reaction is good. After the power cycle test of 200 and 400, the temperature rise is still within 20K, which is a safe choice for small high density battery pack.

It can be used for 10 years to provide the battery pack outlet connector of the power tram for the listed companies in South Korea, which is the quality answer. M10 cable using.