1. Performance and price

The working principle of a lithium battery is an electrochemical device that converts chemical energy into electrical energy. In this process, a medium is needed to transmit the electrical energy converted from chemical energy, and a conductive material is required. Among ordinary materials, metal materials are the most conductive materials; among metal materials, copper foil and aluminum foil are cheap and good conductivity. At the same time, in lithium batteries, we mainly have two processing methods: winding and lamination. Compared with winding, the pole piece used to prepare the battery needs to have a certain degree of flexibility to ensure that the pole piece will not be brittle and broken during winding. Among metal materials, copper and aluminum foil are also softer metals. The last thing is to consider the cost of battery preparation. Relatively speaking, the price of copper and aluminum foil is relatively cheap, and the resources of copper and aluminum elements are abundant in the world.

2. Stability

Aluminum is easy to chemically react with oxygen in the air, forming a dense oxide film on the surface of aluminum to prevent further reaction of aluminum, and this thin oxide film also has a certain protective effect on aluminum in the electrolyte. Copper itself is relatively stable in the air and basically does not react in dry air.

3. Potential situation

The positive electrode potential is high, copper foil is easily oxidized at high potential, and the oxidation potential of aluminum is high, and the surface layer of aluminum foil has a dense oxide film, which also has a good protective effect on the internal aluminum. Both are used as current collectors because they have good electrical conductivity and soft texture (maybe this is also conducive to bonding), and they are relatively common and cheap. At the same time, a layer of oxide protective film can be formed on the surface of both.