Copper Foil For Lithium Electric Materials

Copper foil can be divided into electrolytic copper foil and calendered copper foil according to the manufacturing process. In March 2000, the United States Electronic Circuit Interconnection and Packaging Association (IPC) issued the "Metal foil for Printed board" (IPC - 4562). IPC - 4562 standard is a comprehensive specification of copper foil variety, grade, performance of the world's authoritative standard. It has the advanced nature of the world, it replaced the original world most copper foil manufacturers carried out by the IPC - MF - 150G standard. IPC-4562 specifies the types and codes of metal foils: E-electrolytic copper foil, W-calendered copper foil. Electrolytic copper foil refers to electrodeposited copper foil (electrodeposited copper foil); wrought copper foil with wrought copper foil, also called wrought copper foil (wrought copper foil).

At present lithium battery inside, the most used or electrolytic copper foil. Electrolytic copper foil is made of copper sulfate solution as raw material. Copper ions are precipitated on the rotating cathode made of titanium or stainless steel, and the precipitated copper foil is continuously peeled off to make copper foil. Then the surface is treated according to the requirements of use.

Several definitions of electrolytic copper foil:

Cathode surface: refers to the side near the cathode roll, this side out is the smooth surface;

Anode surface: refers to the side without cathode roller, this side is generally wool surface.

According to the later treatment of copper foil, copper foil can be divided into: single-sided hair, double-sided hair and double-sided light.

Single side hair is directly electrolyzed copper foil after oxidation prevention treatment and copper foil.

Double-sided wool is the copper foil electrolyzed out by the smooth surface of the cathode roller and then through the surface processor for wool treatment (plated with a layer of copper particles), and then by anti-oxidation treatment and obtained foil.

Double-sided light is the electrolytic anode hair surface through a special process to make the crystalline structure of copper foil smooth, detailed, resulting in the surface color, roughness and smooth surface close, and then through anti-oxidation treatment.

In the early days, single-sided wool was used inside lithium batteries, but due to the poor consistency of both sides, the consistency of the battery between the whole batch is also problematic. Therefore, most manufacturers now use double-sided copper foil. Moreover, the grain of the surface and the grain of the surface are not the same, the contact of the surface and the active substance is spot-like, and the smooth surface is the surface contact, so the influence of the internal resistance and cohesiveness of the battery is not the same. In addition, the tensile strength and elongation of the smooth copper foil are better than that of the rough surface due to the different crystal structure.

The key technical indicators for copper foil are:

1. Surface roughness, which is an important parameter for cohesiveness, especially oily negative electrode;

2, the surface tension, dyne index must be small, so as to make the stock spread evenly, the size of the surface tension and the surface coating elements are related to the current domestic foil are basically nickel plating and zinc plating, so the surface tension is relatively large, but the foreign are chrome plating, oxidation resistance is stronger, and the surface tension is smaller. The Japanese and Taiwanese foil are mostly chrome-plated.

Others are general metrics, such as:

1. Thickness;

2. Surface density;

3. Normal tensile strength;

4. Normal elongation;

5, high temperature tensile;

6, high temperature elongation;

7. Appearance, etc.

At present, the main problems of domestic copper foil are as follows: roughness inconsistency on both sides is serious, roughness instability between batches; Lack of surface oxidation resistance; Excessive surface tension. Improvements are urgently needed.