[agency Review] Power Battery Industry: PET Copper and Aluminum foil industrialization begins

There are some hidden dangers in electrolytic copper foil, such as capacity reduction, battery thermal runaway and so on. In the lithium battery industry, the mainstream negative current collector is pure copper electrolytic copper foil with a thickness of about 6-9um. In the process of battery charge and discharge, the volume of the negative electrode material also changes, and the copper foil as the negative current collector will continue to stretch and contract, and the loss of the negative electrode material may lead to the decrease of capacity, the decline of performance, the increase of resistance, the increase of heat production and other hidden dangers. In addition, after the battery is out of control due to the damage of dendrite growth and external force, there is a safety risk of battery deflagration. The compound current collector is like a safety, and the acupuncture site is quickly disconnected after acupuncture, thus ensuring the safety of the battery.

PET composite aluminum film and copper foil are good substitutes for traditional lithium battery current collector (aluminum foil and copper foil). Among them, the composite aluminum film is 1x2 of the thickness of the traditional aluminum foil, and the weight is lighter; the composite copper film is 3 of the thickness of the traditional copper foil, and the same weight is lighter. It is of great significance to improve the energy density, safety and cost of lithium battery, and has a broad market prospect. And this technology has great universality, and other composite film materials such as composite copper foil and aluminum foil can also be used.

The composite copper foil is used to deposit copper in vacuum on the surface of the plastic film with a thickness of 4murmur6 microns, making a metal layer of about 50-80nm, metallizing the film, and then using water medium electroplating to thicken the copper layer to 1 micron, and the overall thickness of the composite copper foil is between 5murmur8 microns, to replace the traditional electrolytic copper foil. The PET composite copper foil can save about 2max 3 of copper, significantly reduce the material cost, and further expand the cost reduction space of the battery after mass production.

Compared with traditional copper foil, PET composite copper foil has four advantages:

1. High safety: the plastic diaphragm in the middle of the composite copper foil can greatly improve the combustion safety of the battery.

2. High specific capacity: in the same case, the amount of copper is only the same as that of the original one, and part of the copper is replaced by plastic, which reduces the weight of the battery and increases the energy density of the battery.

3. Long life: reducing the shedding of active material caused by metal shrinkage can improve the cycle life of the battery.

4. Strong compatibility: suitable for lithium battery environment.

Technology and technology

The difficulty of composite fluid collection lies in the close combination of organic polymers and inorganic metals. The key process can be divided into two steps: the first step is vacuum magnetron sputtering, using PVD (physical vapor deposition) method to sputter a layer of dozens of nm metal on the surface of PET with 4.5um thickness, and the second step is using ion replacement to thicken the metal layer on the surface, and the thickness of copper is about 900nm.

PVD process is the key of composite current collector technology. At present, there are three kinds of processes: magnetron sputtering, electron beam evaporation and hot evaporation. The application of PVD technology in the field of semiconductors has been relatively mature.

Ion replacement has technical similarities with traditional electroplating methods, but the composition of the solution is relatively simple and only involves copper as a heavy metal.

The electroplating equipment in China is represented by Dongwei Science and Technology and other enterprises, and this step has a large degree of similarity with the electrolytic copper plating process of traditional copper foil enterprises. Dongwei Science and Technology is the leader of domestic precision electroplating equipment, the main products are PCB electroplating special equipment and its supporting equipment, general hardware electroplating equipment.

Compared with the traditional copper foil process, the main advantages of PET copper plating are as follows:

The main results are as follows: 1. The technological process is greatly shortened, the vacuum coating process is used to form the film surface as the cathode, which can react directly in the ion replacement equipment, and the vacuum process has no pollution, and the copper dissolution electrolysis process of copper foil also has pollutant emission.

2. The new medicament system is adopted to avoid the highly toxic substances such as cyanide, so that the discharge amount of pollutants in the production process is better, and the pollutants are easier to deal with.

3. The organic antioxidant solution is used for antioxidation, and the antioxidant is dried directly, and the medicament is recycled. The discharge of metal pollutants is avoided.

Materials and equipment companies are expected to benefit

Compound current collector is an important breakthrough in safety technology in recent years. Chongqing Jinmei, which is indirectly invested by Ningde, has formed the core technical achievements from the aspects of material design, equipment and technology, battery application and so on. Soteria, an overseas start-up, has also made patent layouts in this area.

Chongqing Jinmei New material is a leader in composite film technology, with a number of patents for the preparation process and equipment of conductive composite films. The company is indirectly owned by Changjiang Morning Road (21.26%) and China Baoan (4.42%) (August 2021).

According to reports, the company has established a cooperative relationship with a number of domestic new energy vehicle battery manufacturers and become a supplier of core materials, and the independently developed polymer composite membrane products have been successfully applied to new energy vehicle batteries, and have successfully passed the German puncture test and entered the stage of mass production.

According to the company's EIA report in August 2021, Chongqing Jinmei plans to expand "Electronic Composite Copper Film, Composite Aluminum Film" in Zone An of Qijiang District Industrial Park in Chongqing, automation equipment manufacturing, robot system integration project (Phase I). After the expansion project is fully completed, it can achieve an annual output of 36 million square meters of "electronic composite aluminum film" and 36 million square meters of "electronic composite copper film", each with 6 production lines. The total investment is 220 million yuan.

Chongqing Jinmei original electronic composite aluminum film (MA) 4 million square, electronic composite copper film (MC) 24 million flat, after the expansion of the project, the annual output will reach 40 million square electronic composite aluminum film (MA), 60 million square electronic composite copper film (MC). According to the membrane material consumption per unit GWh battery, we estimate that the battery capacity is equivalent to 6GWh, and the company's capacity is expected to expand further in the future.

Investment suggestion

Composite current collector is an important breakthrough in safety technology in recent years. the application field of this technology can be extended to other film materials, such as composite copper foil, composite aluminum foil and so on. The industrialization process of PET copper foil and aluminum foil is expected to accelerate in the next few years, reaching the corresponding mass production scale of battery GWh level; but compared with traditional lithium copper foil, the scale of PET copper foil / aluminum foil is still small in the short and medium term. It is suggested that we should pay attention to the investment opportunities and subdivision pattern optimization brought about by technological change.

The main results are as follows: (1) Chongqing Jinmei's compound current collector technology and industrialization, which was indirectly invested in Ningde era, has made great progress, and the expansion project is expected to be widely used in batteries in the future. Pay attention to Chongqing Jinmei (unlisted), Ningde era, Dongwei Science and Technology;

(2) traditional copper foil enterprises have strong investment, production expansion and adaptability, and the electroplating process of PET copper plating is similar to the existing process, and the pattern of shortage of supply and demand of lithium copper foil in the past two years has not been broken, and it still has the certainty of rising both in quantity and price. Pay attention to Jiayuan Technology and Nord shares.