The working principle of composite metal foil mainly depends on its unique structure and manufacturing process. Composite metal foil is usually formed by stacking multiple layers of metal foil in parallel, with high degree of freedom in the stacking method, small conductor size, and high coil filling rate of magnetic components. Multiple coils are formed by winding the wire on the current-sharing magnetic ring. When the current of any layer of metal foil changes, due to the mutual inductance of the coil, the current change trend of each wire is basically the same, thereby reducing or eliminating the problem of uneven current of multiple layers of metal foil.
Working principle of composite copper foil
Taking composite copper foil as an example, its working principle involves multiple steps and technical routes:
Preparation method: There are three main methods for preparing composite copper foil: one-step method, two-step method and three-step method. The one-step method directly forms a copper layer of a specified thickness on both sides of a polymer film by vacuum magnetron sputtering or vacuum evaporation, but the cost is high and the technology is not mature; the two-step method is to metallize copper by vacuum magnetron sputtering, and then thicken the copper layer by water electroplating. It is the most mature and cost-controllable technical route at present; the three-step method combines vacuum magnetron sputtering, vacuum evaporation and water electroplating, which improves the sputtering efficiency but the process is not mature enough.
Structural features: The composite copper foil adopts a "sandwich" structure, with a polymer film such as PET (polyethylene terephthalate) as the base film, and copper is metallized on both sides by vacuum coating technology, and then the copper layer is thickened by water electroplating. This structure is not only light and thin, but also has the characteristics of high safety, low cost, long life and high mass energy density.
Application field: Composite copper foil is mainly used in the field of lithium batteries as a current collector. The current collector plays the role of collecting current in lithium batteries, collecting and outputting the current generated by the active material, and inputting it to the active material. Due to its trend of becoming lighter and thinner, composite copper foil can reduce costs and reduce the amount of copper foil used, thereby improving mass energy density.