Aluminum plastic film – not achieved localization of lithium materials
Aluminum plastic film, which plays the role of encapsulation in the upstream materials of lithium battery industry chain, can be said to be the core material of soft pack battery, accounting for 10-20% of the total material cost.
Table of Contents
Aluminum plastic film production technology is much more difficult than diaphragm, electrolyte, cathode materials, and is a material that has not yet been fully localized in lithium batteries.
In recent years, with the progress of related enterprises in technology and the improvement of production capacity, aluminum-plastic film has gradually embarked on the road of localization.
According to the different forms of packaging, lithium-ion batteries can be divided into 3 categories.
Cylindrical lithium battery with stainless steel package, square lithium battery with aluminum alloy package and soft package lithium battery with aluminum-plastic film package.
Due to the flexibility of shape and size, soft pack lithium batteries can meet the requirements of higher energy density and adapt to the development trend of “thinner” and “smaller” batteries.
In recent years, China’s 3C market is booming and the strong downstream demand of new energy vehicle market has led to the continuous increase of lithium battery production and sales, especially the continuous increase of demand for soft pack lithium batteries, and aluminum plastic film as packaging material for soft pack lithium batteries has started to receive more and more attention.
This has provided huge development opportunities for Chinese aluminum plastic film enterprises, and the corresponding technology research and development has also become a booming trend.
Aluminum plastic film structure composition
Aluminum-plastic film flexible packaging can be divided into three layers, and the layers are combined with each other through adhesives.
The inner layer is designed for the electrolyte in lithium-ion batteries and has a relatively good role in chemical stability. As a stable composite layer and heat seal layer, more film materials such as polypropylene, polyethylene, ethylene acrylic copolymer, polypropylene or ionic cross-linked polymer resin are used, which can improve the electrolyte resistance of the packaging material and ensure the performance of the final battery and longer service life.
The middle layer of carbon coated aluminum foil is the barrier layer, the main function is to block the water from entering the battery and the electrolyte from seeping out from the inside, it needs to have good barrier performance.
The outer layer is called the protective layer because the outer material used has good heat resistance (160°C ± 15°C), wear resistance, puncture resistance and bending resistance, so it has good protection for the barrier layer.
In addition, there are certain requirements for printability. Considering the cost of the outer layer material, we usually choose polyester and nylon non-ferrous metal processing film materials.
Aluminum plastic film production process
In production, the main processes used in aluminum-plastic film are dry and thermal.
The dry process is to bond aluminum and polypropylene with adhesive and then synthesize under dry pressure; the thermal process is to bond aluminum and polypropylene with polypropylene porous foam and then synthesize under slow temperature and pressure rise and hot pressure.
The main advantages of dry process aluminum-plastic film are good deep-drawn molding performance, excellent short-circuit resistance, few surface defects, and fast manufacturing speed, simple procedures, and low cost.
However, its peeling force is small, and the properties of electrolyte resistance and water resistance need to be ensured by adding special adhesives.
The aluminum-plastic film produced by the thermal process has a large bonding force between the aluminum and polypropylene layers, and its ability to prevent electrolyte dissolution and peeling of the inner surface layer is improved. However, this specially treated binder needs to be melted at a higher temperature in order to act as a bonding agent.
Due to the difference in the shrinkage coefficient of each material, it tends to curl inward during cooling and has poor appearance and cutting performance. In addition, the heating makes the material brittle, its short-circuit resistance is poor, and the preparation process is relatively complex.
In summary, the dry lamination process is more common in the preparation of aluminum-plastic film process, and the application is also more extensive, such as cell phone batteries and other batteries requiring high energy weight, electric vehicles and other large multiplier, high-capacity power batteries; thermal lamination is generally only used in 3C and other fields that do not require high battery capacity.
Aluminum-plastic film competition market
The technical barrier of aluminum-plastic composite film for lithium battery is very high, Chinese enterprises in the upstream of aluminum-plastic film nylon, CPP, calendering aluminum foil, binder and other raw materials, such as self-sufficiency, even if the high-end nylon technology has been broken through in recent years, but the higher cost of CPP, aluminum foil is still dependent on imports, and this is the key reason why the Chinese market is occupied by international enterprises for a long time.
DNP, Showadenko and other Japanese and Korean companies, occupying more than 70% of the global market share, have formed production and technology monopoly in the world.
At present, domestic aluminum plastic film is mainly used in the low-end 3C consumer electronics field, high-end 3C consumer electronics aluminum plastic film and power soft pack battery aluminum plastic film used by international enterprises to provide raw materials, high-end products rely on a high degree of import.
The development of new energy vehicles will become an important driving force for the boom of the aluminum film industry, and there is huge space for domestic replacement of aluminum film.
One of the reasons is that Japanese and Korean companies have limited capacity of existing aluminum plastic film, and the expansion rate is slow, so the capacity cannot keep up with the rapid development of the global flexible packaging industry; at the same time, the cooperation between Japanese and Korean companies and Chinese customers is low, and Chinese manufacturers have an advantage in supply chain security because they are more cooperative.
At present, more and more Chinese companies have started to layout the aluminum-plastic film industry and gradually make progress and breakthrough in aluminum-plastic film technology.
It is understood that mg-crown, Putailai many companies are in the process of verification, and in the huge pressure of cost reduction, soft pack battery manufacturers began to try to have a greater price advantage of Chinese-made aluminum plastic film products.
According to the research data, the demand for aluminum plastic film for lithium batteries in China is expected to exceed 200 million square meters in 2022, with a year-on-year growth of over 40%.
Meanwhile, the localization rate of aluminum plastic film is gradually increasing, and in 2022, the localization rate in China is expected to exceed 60%, while in 2020, the localization rate of aluminum plastic film in China is less than 30%.
Ayan Chen
Dear readers, My professional journey began with a master's degree in Electronic Engineering, after which I directed my focus towards in lithium battery swap systems. As a engineer at a renowned battery company, I've not only wholeheartedly contributed to several successful battery swapping station projects, but have also gained a wealth of experience. Through my writing, I aspire to share insights and knowledge about motorcycle battery swapping for you.
Aluminum plastic film – not achieved localization of lithium materials
Aluminum plastic film production technology is much more difficult than diaphragm, electrolyte, cathode materials, and is a material that has not yet been fully localized in lithium batteries.
In recent years, with the progress of related enterprises in technology and the improvement of production capacity, aluminum-plastic film has gradually embarked on the road of localization.
According to the different forms of packaging, lithium-ion batteries can be divided into 3 categories.
Cylindrical lithium battery with stainless steel package, square lithium battery with aluminum alloy package and soft package lithium battery with aluminum-plastic film package.
Due to the flexibility of shape and size, soft pack lithium batteries can meet the requirements of higher energy density and adapt to the development trend of “thinner” and “smaller” batteries.
In recent years, China’s 3C market is booming and the strong downstream demand of new energy vehicle market has led to the continuous increase of lithium battery production and sales, especially the continuous increase of demand for soft pack lithium batteries, and aluminum plastic film as packaging material for soft pack lithium batteries has started to receive more and more attention.
This has provided huge development opportunities for Chinese aluminum plastic film enterprises, and the corresponding technology research and development has also become a booming trend.
Aluminum plastic film structure composition
Aluminum-plastic film flexible packaging can be divided into three layers, and the layers are combined with each other through adhesives.
Inner layer – multifunctional layer (thickness 40μm～80μm)
The inner layer is designed for the electrolyte in lithium-ion batteries and has a relatively good role in chemical stability. As a stable composite layer and heat seal layer, more film materials such as polypropylene, polyethylene, ethylene acrylic copolymer, polypropylene or ionic cross-linked polymer resin are used, which can improve the electrolyte resistance of the packaging material and ensure the performance of the final battery and longer service life.
Intermediate layer – barrier layer (thickness 35μm ~ 40μm)
The middle layer of carbon coated aluminum foil is the barrier layer, the main function is to block the water from entering the battery and the electrolyte from seeping out from the inside, it needs to have good barrier performance.
Outer layer – protective layer (thickness 15μm～25μm)
The outer layer is called the protective layer because the outer material used has good heat resistance (160°C ± 15°C), wear resistance, puncture resistance and bending resistance, so it has good protection for the barrier layer.
In addition, there are certain requirements for printability. Considering the cost of the outer layer material, we usually choose polyester and nylon non-ferrous metal processing film materials.
Aluminum plastic film production process
In production, the main processes used in aluminum-plastic film are dry and thermal.
The dry process is to bond aluminum and polypropylene with adhesive and then synthesize under dry pressure; the thermal process is to bond aluminum and polypropylene with polypropylene porous foam and then synthesize under slow temperature and pressure rise and hot pressure.
The main advantages of dry process aluminum-plastic film are good deep-drawn molding performance, excellent short-circuit resistance, few surface defects, and fast manufacturing speed, simple procedures, and low cost.
However, its peeling force is small, and the properties of electrolyte resistance and water resistance need to be ensured by adding special adhesives.
The aluminum-plastic film produced by the thermal process has a large bonding force between the aluminum and polypropylene layers, and its ability to prevent electrolyte dissolution and peeling of the inner surface layer is improved. However, this specially treated binder needs to be melted at a higher temperature in order to act as a bonding agent.
Due to the difference in the shrinkage coefficient of each material, it tends to curl inward during cooling and has poor appearance and cutting performance. In addition, the heating makes the material brittle, its short-circuit resistance is poor, and the preparation process is relatively complex.
In summary, the dry lamination process is more common in the preparation of aluminum-plastic film process, and the application is also more extensive, such as cell phone batteries and other batteries requiring high energy weight, electric vehicles and other large multiplier, high-capacity power batteries; thermal lamination is generally only used in 3C and other fields that do not require high battery capacity.
Aluminum-plastic film competition market
The technical barrier of aluminum-plastic composite film for lithium battery is very high, Chinese enterprises in the upstream of aluminum-plastic film nylon, CPP, calendering aluminum foil, binder and other raw materials, such as self-sufficiency, even if the high-end nylon technology has been broken through in recent years, but the higher cost of CPP, aluminum foil is still dependent on imports, and this is the key reason why the Chinese market is occupied by international enterprises for a long time.
DNP, Showadenko and other Japanese and Korean companies, occupying more than 70% of the global market share, have formed production and technology monopoly in the world.
At present, domestic aluminum plastic film is mainly used in the low-end 3C consumer electronics field, high-end 3C consumer electronics aluminum plastic film and power soft pack battery aluminum plastic film used by international enterprises to provide raw materials, high-end products rely on a high degree of import.
The development of new energy vehicles will become an important driving force for the boom of the aluminum film industry, and there is huge space for domestic replacement of aluminum film.
One of the reasons is that Japanese and Korean companies have limited capacity of existing aluminum plastic film, and the expansion rate is slow, so the capacity cannot keep up with the rapid development of the global flexible packaging industry; at the same time, the cooperation between Japanese and Korean companies and Chinese customers is low, and Chinese manufacturers have an advantage in supply chain security because they are more cooperative.
At present, more and more Chinese companies have started to layout the aluminum-plastic film industry and gradually make progress and breakthrough in aluminum-plastic film technology.
It is understood that mg-crown, Putailai many companies are in the process of verification, and in the huge pressure of cost reduction, soft pack battery manufacturers began to try to have a greater price advantage of Chinese-made aluminum plastic film products.
According to the research data, the demand for aluminum plastic film for lithium batteries in China is expected to exceed 200 million square meters in 2022, with a year-on-year growth of over 40%.
Meanwhile, the localization rate of aluminum plastic film is gradually increasing, and in 2022, the localization rate in China is expected to exceed 60%, while in 2020, the localization rate of aluminum plastic film in China is less than 30%.