Why use copper foil for negative electrode and aluminum foil for positive electrode of lithium battery pack?

Why lithium batteries use copper foil as the negative electrode, and aluminum foil as the positive electrode. The commonly used positive electrode collector of lithium batteries is aluminum foil, and the negative electrode collector is copper foil. In order to ensure the stability of the collector in the battery, the purity of both is required to be above 98%. With the continuous development of lithium battery technology, whether it is used for digital products lithium batteries or battery electric vehicles, we all hope to have the highest possible energy density batteries. The weight of lithium battery packs is getting lighter and lighter. In the collector, the most important The reduction in weight can intuitively reduce the volume and weight of the battery. There are three reasons for using aluminum foil as the positive electrode of lithium batteries and using copper foil as the negative electrode. First of all, copper foil and aluminum foil have good electrical conductivity, soft texture and low price. As we all know, lithium batteries work by converting chemical energy into electrical energy through electrochemical devices. In this process, we need a medium to convert chemical energy into electrical energy. In general data, metal data is the best conductivity data, while in metal data, the cheap conductivity and good ones are copper foil and aluminum foil. At the same time, in terms of lithium batteries, we mainly have winding and laminated production. Compared with winding, the pole pieces required for battery preparation have a certain degree of flexibility to ensure that the pole pieces will not become brittle during winding. In metal materials, copper foil is also a soft metal. Finally, considering the cost of battery preparation, copper foil is relatively cheap, and there are abundant copper and aluminum resources in the world. Secondly, copper foil is relatively stable in the air. The attack of aluminum and oxygen is a very simple chemical reaction. An oxide film appears on the surface of aluminum to prevent further reaction of aluminum. This thin oxide film also has a certain maintenance effect on the aluminum electrolyte. Copper is relatively stable in air, but does not react in dry air. The third is to distinguish the potential of the positive and negative electrodes of lithium batteries with aluminum foil for the positive electrode and copper foil for the negative electrode, not the other way around. The positive electrode potential is high, the copper foil is easily oxidized under high potential, and the oxidation potential of aluminum is high, and the surface of the aluminum foil has a dense oxide film, which also has a good protection function for the aluminum interior. These two materials were chosen for fluid collection because they have good conductivity, soft texture (which may also help bonding), are relatively common and relatively inexpensive, and can form an oxidation maintenance film on both surfaces . With the rapid development of lithium batteries in recent years, the requirements for the thickness of copper foils for lithium batteries are becoming higher and higher. The positive aluminum foil dropped from 16um to 14um a few years ago, and then to 12um. Many battery manufacturers have already processed aluminum foils of 10 microns or even 8 microns in batches. Due to its good flexibility, the copper foil used for the negative electrode is reduced from 12um to 10um, and then to 8um. So far, a large number of battery manufacturers have begun to process 6um in batches, and some manufacturers are developing 5um/4um batteries for use. Because lithium batteries have higher requirements for the purity of copper foil and aluminum foil, the data density is basically at the same level. As the developing thickness decreases, the surface density also decreases correspondingly, and the composition of the battery naturally becomes smaller and smaller. This is why lithium batteries use copper foil as the cathode and aluminum foil as the anode. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.