27A battery

Domestic 27A battery need aluminum-plastic film materials

Aluminum-plastic film is one of the five major materials for 27A battery and is a packaging material for soft-pack lithium batteries. The aluminum-plastic film consists of five layers: outer nylon layer/adhesive/middle aluminum foil/adhesive/inner heat-sealing layer, and each layer has relatively high functional requirements.

1. The role of aluminum-plastic film for 27A battery

Aluminum-plastic film is one of the five major materials for 27A battery and is a packaging material for soft-pack lithium batteries. The aluminum-plastic film consists of five layers: outer nylon layer/adhesive/middle aluminum foil/adhesive/inner heat-sealing layer, and each layer has relatively high functional requirements. The typical aluminum-plastic film structure is shown in the figure below:

2. Requirements for aluminum-plastic film for 27A battery

The barrier ability, puncture resistance, electrolyte stability, high temperature resistance and insulation of aluminum-plastic film affect the performance of 27A battery. Any lack of any aspect may lead to a decline in battery performance and direct scrapping. Aluminum-plastic film is produced using precision coating technology. At present, Japanese companies have the most advanced precision coating technology in the world.

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3. Lithium-ion battery aluminum-plastic film process

Dry process and hot process are the main production processes used for aluminum-plastic film. The dry process is to directly press aluminum and polypropylene after bonding with an adhesive, and the hot process is to use MPP to connect aluminum and polypropylene, and then slowly heat up and press them together.

The aluminum-plastic film produced by the dry process is thin, good in appearance, has excellent deep drawing performance and short circuit resistance, and has a simple process and low cost. However, compared with the hot process, it has poor electrolyte resistance and water resistance; the advantages of the hot process are good electrolyte resistance and water resistance, but the deep drawing forming performance and short circuit resistance are not as good as the dry process, and the appearance and cutting performance are poor.

4. Global lithium-ion battery aluminum-plastic film companies

Aluminum-plastic film plays a key role in soft-pack lithium batteries, generally accounting for about 15-20% of the cost of the battery cell. However, due to the lack of technology in China, the aluminum-plastic film market share is very small, accounting for less than 5%. At present, 90% of the domestic aluminum-plastic film market is monopolized by Japanese manufacturers, mainly DNP (Dai Nippon Printing), Showa Denko and T&T.

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As a lithium battery material that has not yet been domestically produced, the gross profit margin of aluminum-plastic film is as high as 60-80%. It is estimated that the global market space for aluminum-plastic film is only tens of billions of yuan. With the increase in downstream demand, the industry growth rate is expected to exceed 40%, and the potential market size will reach tens of billions.

5. The gap between aluminum-plastic film and lithium-ion battery in my country

As the core material of soft-pack batteries, the production technology of aluminum-plastic film is much more difficult than that of diaphragm, positive electrode, negative electrode and electrolyte, and is one of the three high technologies in the lithium battery industry. From the perspective of product performance, there is a big gap between my country's aluminum-plastic film products and foreign products, mainly manifested in: backward aluminum foil surface treatment technology and high pollution; aluminum foil water treatment will produce "hydrogen embrittlement", resulting in poor disassembly resistance of aluminum-plastic film; aluminum foil surface stiffness is not enough, and the yield rate is poor; polypropylene is easy to curl when compounded with high thermal conductivity aluminum foil surface, resulting in layered crystallization; domestic adhesive formulation process is poor, and it is easy to have delamination and peeling problems.

Due to the shortcomings of these production process technologies, the maximum punching depth of aluminum-plastic film products produced in my country is about 5mm, and it has never been able to meet good performance requirements. Foreign countries can reach 8mm, and some even reach 12mm. Overall, there is still a certain gap with foreign products; in terms of thickness, the thinnest domestic aluminum-plastic film can only be 70μm, and mass-produced ones are 112, 88 and 72μm, while the thinnest Japanese aluminum-plastic film can be 40μm, and 65 and 48μm are also mass-produced.

Why is it difficult to make a breakthrough in the manufacturing technology of aluminum-plastic film? Generally speaking, it is mainly due to deficiencies in materials, equipment and processes. The technical difficulty lies mainly in the control of the process - precise control of the reaction conditions.

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