New development of aluminum foil for lithium-ion battery

During the two decades from 2016 to 2035, the compound growth rate of aluminum foil for lithium-ion batteries in China and the whole automobile can reach 15% or even higher. Since the industrial production of aluminum in 1888, never has a product grown at such a high rate for such a long time. In this paper, the basic concept of electronic / battery aluminum foil is introduced, and the general situation of electronic / battery foil enterprises built and under construction in China in recent years are introduced in detail. According to the data consulted by the author, as of 2021, there are more than 200 large-scale manufacturers of electronic / battery aluminum foil in China, with a total production capacity of about 1.5 million tons per year. The output of battery foil in our country can meet the demand of aluminum foil for the development of automobile battery. The author suggests that in order to improve the performance of lithium-ion battery, especially the performance, it is appropriate to strengthen the research and development of new battery.

Aluminum foil refers to the thin strip of aluminum and aluminum alloy with thickness ≤ 0.2mm, which has different regulations in some other countries (Table 1).

Aluminum foils are generally classified according to thickness, state and use.

According to the thickness: where greater than 0.012mm aluminum foil is called single foil, less than or equal to 0.012mm called double foil; there is also the thickness after the decimal point with a 0 called single zero foil, after the decimal point with two zeros called double zero foil, such as 0.005mm foil can be called double zero 5 foil.

According to the state, it can be divided into full hard foil, soft state foil, semi-hard foil, 3ax 4 hard foil, 1ax 4 hard foil. Full hard foil refers to the unannealed foil after rolling (annealed strip and cold rolled), such as utensil foil, decorative foil, medicine foil, etc.; soft state foil refers to the foil annealed after cold rolling, such as food, cigarettes and other composite packaging materials and electrical foil; where the tensile strength of aluminum foil is between full hard foil and soft foil, such as air conditioning foil, bottle cap foil, etc.; Where the tensile strength is between full-hard foil and semi-hard foil, such as air-conditioning foil, aluminum-plastic pipe foil, etc., while the tensile strength of aluminum foil is between soft foil and semi-hard foil, it is called 1ax-4 hard foil, where its tensile strength is between full-hard foil and semi-hard foil, such as air-conditioning foil, aluminum-plastic pipe foil, etc.

According to the surface state, it can be divided into single-sided light foil and double-sided light foil. Aluminum foil rolling is divided into single sheet rolling and double rolling. In single sheet rolling, both sides of the foil are in contact with the roll surface, and both sides have bright metal luster, which is called double-sided light foil. In double rolling, only one side of each foil is in contact with the roll, the contact side with the roll is bright, and the two sides of the aluminum foil contact with each other are darkened. this kind of foil is called single-sided light foil. The small thickness of the double-sided glossy aluminum foil mainly depends on the diameter of the work roll, usually not less than 0.01mm, the thickness of the single-sided smooth foil is usually not more than 0.03mm, and the current small thickness can reach 0.004mm.

Aluminum foil can be divided into packaging foil, medicine foil, daily necessities foil, battery foil, electrical and electronic foil, construction foil and so on.

The use of aluminum foil is shown in Table 2.

Battery foil and electrical foil

Battery foil is the aluminum foil used to manufacture battery workpieces, while electrical foil is the aluminum foil used to manufacture various parts of other electrical appliances, which can be collectively referred to as electronic foils. Battery foil is a kind of high-tech products, which can achieve an annual compound growth rate of more than 15% in the next few years. The mechanical properties of cable foil and battery foil are shown in tables 3 and 4. The period from 2019 to 2022 is the period of great development of Chinese battery and foil enterprises. About 200 enterprises have been put into production and are under construction, with a total production capacity of about 1.5 million tons.

Electrolytic capacitor aluminum foil is actually a kind of deep processing product. It is a kind of corrosion material working under polar conditions, and it has high requirements for the structure of the foil. there are three kinds of aluminum foils: cathode foil with thickness of 0.015-0.06mm, high-voltage anode foil with thickness of 0.065-0.1mm, and low-voltage anode foil with thickness of 0.065-0.1mm. The anode foil uses industrial high purity aluminum, the mass fraction should be greater than or equal to 99.93%, and the purity of aluminum used for high voltage anode should be greater than or equal to 4N. The main impurities of industrial high purity aluminum are Fe, Si, Cu, as well as Mg, Zn, Mn, Ni and Ti as trace elements. The Chinese standard only stipulates the content of Fe, Si and Cu, but there is no clear stipulation on the content of other elements. The impurity content of battery aluminum foil abroad is obviously lower than that at home.

According to the thickness of GB/T8005.1, is not less than 0.001mm and less than 0.01mm, aluminum foil is called double zero foil, the commonly used alloys are 1145, 1235, 1350, etc., the most commonly used is 1235, and its Fe/Si ratio is 2.5-4.0. The thickness is not less than 0.01mm and less than 0.10mm. The aluminum foil is called single zero foil, and the capacitors are commonly used with 1235-H18 (thickness 0.020-0.050mm); mobile phone batteries are used with 1145-H18, 8011ml H18, with a thickness of 0.013-0.018mm; and cable foil is used with a thickness of 1235mm, with a thickness of 0.010-0.070mm. The foil with a thickness of 0.10-0.20mm is called zero-free foil, and the main varieties are decorative foil, air-conditioning foil, cable foil, wine bottle cover foil and louver foil.

Overview of China's Aluminum foil Industry in 2020

According to the joint statistics of the China Nonferrous Metal processing Industry Association, in 2020, China's aluminum output reached 42.1 million tons, aluminum foil strip billet 720000 tons, aluminum foil output 4.15 million tons, the finished product rate of 88%, ranking in the forefront, strip production increased by 3.7% over the previous year. The output of aluminum foil varieties is shown in Table 5. From the data in the table, it can be seen that except for the decline of air conditioning foil compared with the previous year, all others have increased, especially the rise of battery foil, which is 16.7%, mainly driven by the rise of automobile batteries. China imported 72000 tons of aluminum foil in 2020, an increase of 4.8 percent over 2019, and exports of 1.233 million tons of aluminum foil in 2020, down 4.8 percent from the same period last year.

In 2020, China's aluminum foil industry applied for 1660 patents, including 500 invention patents, 1121 utility model patents and 39 design patents.

According to statistics, there are more than 500 foil rolling lines in 2020, with a production capacity of more than 5.5 million tons per year. By 2020, China has imported 60-70 sets of German Ashenbach foil mills.

Aluminum foil occupies the place of industrial application in China, accounting for more than 60%, while aluminum foil in industrial developed countries accounts for more than 60% of the application in the field of packaging and household use. The per capita consumption of aluminum foil packaging in China is 0.72 kg in 2020, which is much lower than that in Europe, North America and Japan, which is about 1.2 kg and about 0.9kg. There is still room for growth in the application of aluminum foil in domestic packaging field. The state issued a plastic ban in 2020 and set 2023 as the time node. In addition, the concept of green clearing fee is deeply rooted in the hearts of the people, and aluminum foil packaging will have a bright future.

Lithium battery aluminum foil

Lithium battery is composed of positive current collector (collector electrode), box, sealing plate, negative plate and so on. The corresponding material requirements are: collector foil should not only have high strength and conductivity, but also should be flat; box material should have high strength and formability, but also should have good expansion resistance; sealing material should have good formability and laser weldability; laminated packaging aluminum should have high strength and formability; bus wire has high strength and conductivity, as well as good bending processability.

The battery aluminum foil usually refers to the positive foil of lithium-ion battery, which is actually not exact, so that the non-modified positive foil with about 0.1mm thickness is called current-collecting aluminum foil, which is different from other aluminum foil used in lithium (ion) battery, such as foil in aluminum-plastic film for battery soft package, electrode foil, modified carbon foil and so on. On the one hand, the current collector aluminum foil is the current collector electrode, on the other hand, it is the carrier of the positive or negative material of lithium battery, that is, the lithium material should be coated on it. In fact, current collector aluminum foil can be referred to as battery foil.

Positive structure

The positive electrode is composed of positive current collector (pole ear), high temperature tape, positive substrate and positive material. The polar ear is about 1070, 1060, 1235, 1230, 1100, 8011, 1N30, 3003 and other alloy foils of 0.1mm. The most commonly used alloys are 1235, 1070, 1100 and 3003 because of their high strength. The cathode substrate is about 0.016mm thick foil.

Shell and sealing material

The shell is processed with thin aluminum plate, which requires high formability and strength, as well as high pressure resistance, which can restrain the shell expansion caused by repeated charging and Discharge. The properties of the three kinds of shell plates are shown in Table 6.

The seal is welded by laser, so it should have the performance of laser welding. at the same time, there is no work hardening in the stage of processing riot valve, so it has good formability.

Battery foil

There are two kinds of aluminum foil for lithium-ion battery: flat foil, with high strength, high conductivity and flat, and surface modified foil. There are seven kinds of flat foils developed by Nippon United Aluminum Company: A85, C2F, high strength C2F, FS115, MS812, X383, 503S, among which A85, C2F, 503s are general industrial foils, which can be used in various civil fields. C2F, MS812, X383 alloys have high strength and electrical conductivity, and F5115 alloy has high ductility after painting and baking. Surface modified foil (ASP,Advanced Surface Profile) has high strength, high electrical conductivity and surface roughness, due to surface roughening, the adhesion of active material is greatly improved, at the same time, the amount of adhesive can be reduced, and the battery characteristics can be improved. The production cost of the new coarsening process is lower than that of the traditional process. The properties of flat foil alloys are shown in Table 8.

Aluminum busbar alloy

The conductive bus of lithium battery was originally made of Cu. After switching to aluminum, the electric conductivity of EC1 alloy is equal to that of pure aluminum 1050Mel O, while its strength is 50% higher than that of pure aluminum. The conductivity of EC2 alloy is only 57% of that of copper. If the thickness of the bus plate increases to 1.8 times that of Cu, the conductive current can be equal to that of copper. The mechanical properties of aluminum bus board are shown in Table 9.

Technical characteristics of battery foil

Now what we usually call battery foil refers to the unmodified aluminum foil used for current collector of lithium battery, that is to say, it should be distinguished from other foils used in the battery. On the one hand, it is the electrode of current collector, on the other hand, it is used as the carrier of positive or negative material of lithium battery, that is, lithium material should be coated on it, so a more accurate definition should be aluminum foil for current collector of lithium battery.

Properties of current collector aluminum foil

Because of its special use conditions, fluid collector aluminum foil has very strict requirements on its technical specifications, which belongs to the aluminum foil family. Some specific requirements are as follows:

Foreign matter: lithium battery has high performance in use, so the surface foreign body (impurities) should be strictly controlled. If there is no foreign body control, it can not be used as qualified battery foil. The foreign body can be aluminum powder, can be magnetic material (iron powder), and other substances. The whole production process should be protected to reduce the possibility of bringing in foreign bodies. In the process of finished products, a device for testing foreign bodies should be set up and measured. The foreign body should be ≤ 50mg/ 300000 m2.

Wettability: wettability mainly depends on the liquid contact angle. Liquid contact angle is when a droplet does not expand on the solid surface, at the rendezvous point of gas, liquid and solid, the contact angle θ is used to judge the wetting of liquid to solid (the angle between the horizontal line of solid-liquid interface and the tangent of gas-liquid interface θ, called contact angle): when θ < 900, it is called wetting: when θ > 90 *, it is non-wetting: when θ = 00 or does not exist, it is called wetting; when θ = 1800, it is not wetted. θ = 900 is the dividing line between wetting and wetting.

Because the oil on the surface of aluminum foil can not be removed, and the uneven surface wrinkles will have a great impact on its surface tension, it is not realistic to measure the contact angle directly, so the dyn value is used to reflect the wetting ability in production practice. the higher the dyn value, the more wettability. However, at present, some customers, especially in Japan and other places, still use the contact angle method to measure the wettability of aluminum foil surface. In order to be consistent with the customer's testing method, at present, a small number of domestic manufacturers also adopt the contact angle method, but this method is greatly affected by factors, measuring instruments and measuring methods, and the measured data obtained can only be reference values. at present, most manufacturers use the surface factor measurement method.

Dyne value is a popular term, which should be the coefficient of surface tension, which mainly expresses the magnitude of surface tension, that is, the force of pulling each other per unit length between the two adjacent parts of the liquid surface. In the SI system, the unit of surface tension is N _ hand m, but it is still commonly used in Diane / cm (dyn/cm), 1dyn/cm=1mN/m. Wettability of finished aluminum foil is generally required to be ≥ 32mN/m.

Surface wetting tension is one of the important technical indexes of battery foil, which affects the adhesion quality of the coating, especially the coating firmness of carbon foil. When the da value is low, the adhesion between aluminum foil and adhesive material is not firm, missed coating and other defects. The surface dynane value of aluminum foil is more than 32 Dynamum mm, and some demanding carbon-coated products even reach 34dyn/mm.

At present, although the national standard has a clear stipulation for the detection method of dyn value, in the actual operation process, different companies and enterprises have different detection methods, so there will be a big gap in the test results. with the rapid development of the battery foil market, it is particularly important to further standardize and unify the detection methods and criteria of dyn value.

Flatness: flatness is a term in the non-ferrous metal industry, but in the battery foil industry, it is called tension. The difference in this term is mainly due to different industries. But whether it is the shape or tension, it expresses a meaning, that is, the flatness of the product. In the battery industry, two terms are used to describe the shape and quality of the product: tension and the amount of collapse. Although this is an unscientific term, it will not change because it has been widely accepted in the battery industry. for the shape of the plate, the battery industry has formed its own standard and measuring device. therefore, the battery industry has changed the original definition of the aluminum processing industry when defining the term.

In short, tension is the shape of the plate, and the amount of collapse is the amount of sag at the edge of the product under the specified tension and length.

Shape quality is a key technical index for battery foil. in the future, with the development of the industry and the continuous improvement of battery product accuracy, users will have higher and higher requirements for aluminum foil shape. How to improve the shape quality of products through process optimization and technological innovation is an important issue in front of the aluminum foil industry.

Mechanical properties: the requirements for mechanical properties of different grades of battery foils are shown in Table 10.

Ordinary strength battery foil is a commonly used single zero foil, which has no other requirements except alloy, while high strength battery foil is produced by process, especially when the thickness is less than 0.015mm, it is difficult to produce, so it needs to be greatly improved in equipment, process and lubrication. The tensile strength of 310MPa is the strength of industrial pure aluminum in H state. The improvement of the tensile strength of the battery foil is inversely proportional to its thickness, that is, the thinner the battery foil, the higher the strength. For example, the tensile strength of the original 0.02mm foil is ≥ 170MPa, while that of the thick 0.013mm foil is ≥ 190MPa. The reason why users want to increase the strength is to reduce the thickness in order to increase the energy density.

The tensile strength of battery foil made in China is generally ≥ 160MPa, but it is difficult to reach more than 200MPa. However, there are many companies that can commercially produce battery foil ≥ 200MPa, and some companies can produce ≥ 280MPa.

Thickness: the thickness of the battery foil has dropped from 20 μ m at the beginning of the new century to 6 μ m in 2020, all the way down (20, 16, 15, 13, 10, 9, 8, 6). However, in order to maintain the burst resistance, constantly improve the tensile strength. Many battery manufacturing companies require that the thickness deviation of the foil is less than 2%. It is not easy to meet this requirement with a foil mill equipped with a general AGC thickness control system. Fortunately, ABB and other companies have developed this kind of thickness control system, which can produce battery foil with high thickness difference.

Trimming quality: in the production of aluminum foil, battery foil is a kind of highly processed products, which has strict requirements for its trimming quality. Defects such as cracked edges and burrs are not allowed. In addition, compared with ordinary foil, battery aluminum foil has its special requirements for edge cutting quality: when there is no tension, the edge peak should not be more than 2mm, and the cross-section aluminum powder tape method should be less than 25 / 10cm.

Surface quality: battery foil also has strict requirements for surface quality. The > 1mm spot is not allowed on the surface, the 0.5mm~1mm convex spot is not allowed on the dark side, it should be less than 3 / m2, and the < 0.5mm spot is not allowed to appear in slices. In addition, for single-sided light products, bright spot defects are not allowed on the dark side. The length of black oil lines less than 5mm should be less than 3. Other surface quality defects: bottom wrinkling length ≤ 10m, lever print < 50m.

Alloy: at present, the main alloys used for battery foil are: 1070, 1060, 1235, 1230, 1100, 8011, 3003, 1N30, etc., covering almost all kinds of alloys used in aluminum foil, but mostly used in 1235, 1060, 1070 industrial pure aluminum, 1100, 3003 alloy is mainly used in the production of strength battery foil.

Key Technology and Market

Key technology

Battery aluminum foil is a deep processing product of aluminum foil, so it is much more difficult to produce than ordinary aluminum foil, and the key technology is also much more. First, the thickness requirement is strict, in the nominal thickness of the product, it is getting thinner and thinner, hoping to reach 9 μ m or even 8 μ m double-sided light, which has exceeded the current small rolling limit thickness of aluminum foil products. And the thickness accuracy is required to be ±2%, which is the highest in all aluminum foil products at present. However, it is not difficult for China to produce such thin aluminum foil, and some companies have long been able to produce 4 μ m foil.

A few days ago, the general battery foil products generally require strength ≥ 180MPa, which is equivalent to the performance of 8-series alloy. With the continuous development of battery technology, for various considerations, many users are constantly improving the strength requirements of battery foil products. At present, the requirement of strength above 200MPa has been very common, and some users even require the strength to reach 270MPa or even 300MPa, which has reached the strength limit of cold hardening of aluminum foil products, and its production is difficult.

In order to meet the needs of the coating process and the carbon coating process, the battery foil has a higher requirement for the surface dyn value, but the high surface dyne value control contradicts with the high strength, and the shape requirement and thickness difference contradict with the high strength ultra-thin rolling, that is to say, the battery foil requires thin thickness, high strength, high surface dyn value, small thickness difference, excellent shape, clean surface, and pursue these six extreme values at the same time.

The development tends to be hot

At present, a large part of battery foil products are not coated with carbon and electrical erosion. However, in order to improve battery performance, reduce interface resistance, protect current collector, reduce polarization, improve battery consistency and life, surface modification of battery foil will gradually become a trend. At present, the treatment technology of battery foil surface is still in continuous development and progress. Carbon coating is carbon coated with 0.5g/m2~2g/m2 on the surface of aluminum foil. After carbon treatment, it is beneficial to improve the rate performance of the battery and prolong the service life of the battery.

Market prospect

The market prospect of battery foil is actually the lithium battery market and the prospect of newly developed batteries. According to the calculation, the amount of aluminum foil used by 1GWh is 600t~800t. In order to protect the environment and achieve the "double carbon" goal, the compound annual growth rate of battery foil is likely to reach 18% or more at least by 2035. China produced about 30, 000 tons of battery foil in 2015, 80, 000 tons in 2020, and is likely to reach 300000 tons in 2025. The author's forecast is likely to be too conservative. In any case, China's aluminum foil industry has sufficient production capacity to meet the needs of the battery industry for aluminum foil. According to the author's survey and statistics of 38 battery / electronic aluminum foil production enterprises, their total production capacity is about 1 million tons / year. With other unstatistics, the total production capacity of battery / electronic aluminum foil in 2021 will reach 1.3 million tons / year, of which 600000 tons / year will be battery foil.

Battery foil market

Due to the rapid development of global new energy vehicles and the strong demand for lithium batteries, the demand for battery aluminum foil is rising rapidly. during the period from 2010 to 2030, the output growth rate of any kind of aluminum products can be compared with that of battery aluminum foil. According to Fan Yuqing's data (Shanghai Aluminum Industry 2016, No. 6, p. 16-27: technical progress and market prospects of aluminum foil for lithium battery current collector) (see Table 11 and figure 1 for relevant data), the compound growth rate of lithium battery aluminum foil production from 2015 to 2025 may reach 25%. If the output in 2015 is 30, 000 tons, then the output in 2025 may exceed 280000 tons, which is a very alarming figure. The aluminum foil of 1GWh lithium battery is about 750t. China is a big producer of lithium (ion) batteries, consuming 45000 tons of lithium battery foil in 2017, accounting for about 58 per cent of total consumption.

In 2017, there were nearly 160 power battery manufacturers in China, and 70 to 80 produced lithium battery foil. Battery foil is a kind of high-tech product, and the demand for its quality is getting higher and higher. There is no problem with ordinary grade foil (tensile strength Rm=150N/mm2~180N/mm2) in China, but there is still a considerable gap between China and developed countries in terms of high strength, high precision thickness deviation and high surface quality.

A list of Battery Aluminum foil and Electronic Aluminum foil Enterprises

By 2020, there are about 45 enterprises (companies, factories) and projects that can produce battery aluminum foil and electronic aluminum foil in China. Before 2020, China is a net importer of these two kinds of aluminum foil, mainly from Japan, accounting for more than 85%. Japan is the manufacturer of this kind of aluminum foil production technology. With the commissioning and gradual production of new projects, the import of battery aluminum foil in China will decrease year by year from this year, and is expected to become a net exporter by 2023. The main production enterprises are as follows:

East Sunshine Technology Holdings Co., Ltd. and Dongyang Guangyou Aixijie Fine foil Co., Ltd. Aluminum foil production capacity of 120000 tons / year

East Sunshine Technology Holdings Co., Ltd. is an important electronic light foil and brazing foil production enterprise in China, a large-scale and technical corrosion foil production base, and also an important hydrophilic foil production base in China. There is a complete industrial chain from aluminum alloy melting-casting, hot-rolling and casting-rolling, cold-rolling to foil-rolling. Ruyuan East Sunshine you Aixijie Jing foil Co., Ltd. is a joint venture between East Sunshine Technology Holdings Co., Ltd. and Japan United Aluminum Co., Ltd. (UACJ, you Aixijie). Nippon United Aluminum Co., Ltd. is not only a large aluminum processing enterprise in Japan, but also a manufacturer of battery aluminum foil technology and production. After the establishment of the joint venture company, we will immediately start the construction of the "annual output of 40,000 tons of high-precision aluminum foil new materials project". After the project is completed and put into production, the production capacity of aluminum plate, strip and foil can reach 150000 tons / year. The emergence of this product will fill the domestic such products and solve the current situation of China's battery foil imports from Japan. Fine foil company will also become an important aluminum foil production base in China with three high-tech core products: electronic foil, brazing foil and battery foil.

Huyanghe Electronic Aluminum foil Base of Zhonghe and Seven divisions in Xinjiang

Xinjiang Zhonghe is an enterprise engaged in the research and development of electronic aluminum foil in China, forming a complete industrial chain of aluminum purification and electronic / battery aluminum foil production, with a high purity aluminum and pure production capacity of nearly 40,000 tons / year, and electronic / battery foil production capacity of about 30,000 tons / year. has become the core backbone enterprises in the field of new aluminum materials in China, Chinese electronic components enterprises.

On June 13, 2020, Hu Yanghe City, Seven Division, and Guidong Electronic Science and Technology Co., Ltd., Hezhou City, Guangxi, signed a project with a total investment of 500 million yuan to build an electronic aluminum foil production line, focusing on building an electronic aluminum foil industry cluster. The project plans to build 100 foil production lines in two phases. the first phase is scheduled to start construction in July 2020 and put into operation in the first half of 2021.

In recent years, the division city has stepped up the work of "attracting investment with business". Relying on the investment attraction enterprises-Xinjiang Rongze Aluminum foil Manufacturing Co., Ltd., it has successively introduced six electronic aluminum foil enterprises, such as Garden Bei Le and Donghao Tiancheng. We will strive to create more than 300 electronic aluminum foil production lines, forming an electronic aluminum foil industry cluster with an annual output value of 5 billion yuan.

Two electronic aluminum foil projects started at the same time in Shihezi, the eighth division of agriculture.

On Sept. 28th, 2018, Xinjiang West Hongyuan Electronics Co., Ltd. invested 700 million yuan in electrode foil expansion project and Xinjiang West Anxing Electronic Materials Co., Ltd. invested 300 million yuan to build 14 million m2 Universe an electronic aluminum foil project. The electrode foil expansion project of Xinjiang Western Hongyuan Electronics Co., Ltd. will build 88 production lines and increase the production capacity of 2000m2/a.

The production capacity of aluminum foil for Luoyang Wanji aluminum processing battery soft package aluminum plastic film is nearly 9000 tons / year.

Luoyang Wanji aluminum processing co., Ltd. Lithium battery soft package aluminum plastic film aluminum foil accounts for 30% of the domestic market. The aluminum foil for aluminum-plastic film in the soft package of the battery is a new main product developed and launched by the technical research team of Wanji Aluminum processing Co., Ltd. Through continuous process optimization and operation parameter adjustment, the company has realized the batch production of aluminum foil for battery soft package aluminum plastic film with various thickness, ultra-wide width and variety.

Aluminum-plastic film is the key material for cell packaging of soft-wrapped lithium battery. Aluminum-plastic film has long been developed, produced and promoted by Japanese enterprises, which has high technical barriers in the lithium battery industry chain, and has higher requirements for raw materials, production technology, equipment and technology. Due to the high technical difficulty, China's aluminum-plastic film industry has been monopolized by Japanese enterprises for a long time, and the price of imported aluminum-plastic film products is high.

Wanji Aluminum processing Company established the R & D technical team of aluminum foil for aluminum-plastic film in 2016, realized small batch trial production in 2018, combined with international technical equipment, broke through the technical bottleneck of low processing efficiency, and achieved the matching of speed and precision in 2019. It has realized the expansion of precision processing technology to the application of the rate industry; in 2020, the products began to be supplied to the domestic market in large quantities.

Wanshun New Materials Co., Ltd. 72000 tons / year electronic foil

Wanshun New Materials Co., Ltd. invested 900 million yuan in 2020 to build a 72000-ton / a high-precision electronic aluminum foil project to be put into production in early 2022, purchasing five foil mills imported from Ashenbach.

Shanghai Enjie Aluminum Co., Ltd. Aluminum-plastic film 270 million m2 Unitora project

In June this year, Changzhou Ruijie New material Technology Co., Ltd., a subsidiary of Shanghai Enjie, invested about 1.6 billion yuan to build eight aluminum-plastic film production lines with an annual production capacity of about 270 million m2.

Aluminum foil production capacity of Dingsheng new material battery is 100000 tons / year.

Dingsheng New Materials Zhenjiang Factory was established in 2003, located in Jingkou Industrial Park, Zhenjiang City, Jiangsu Province, is a high-tech enterprise engaged in aluminum plate aluminum foil research and development, production and manufacturing. The company has a battery aluminum foil production capacity of 60, 000 tons / year in 2020, built 40, 000 tons / year in 2021, totaling 100000 tons / year, and supplied to Tesla Battery Factory in early 2020.

North China aluminum co., Ltd.

North China Aluminum Co., Ltd. was established in 1978. after more than 40 years of development and construction, North China Aluminum Co., Ltd. has developed into a comprehensive aluminum processing base integrating aluminum processing products and equipment manufacturing. Battery foil, plate base, double zero foil and evaporator aluminum tubes are the strategic varieties of the company. After the newly built 60, 000 tons / year battery foil project was put into production in March this year, the comprehensive production capacity of North China Aluminum Industry can reach 210000 tons per year. Among them, 150000 tons of aluminum foil per year. At the same time, the 100000 class m2 dust-free workshop for battery foil production was built, the striping equipment was upgraded and plasma equipment was added, which made sufficient preparations for the quantity of lithium battery aluminum foil products. In recent years, North China Aluminum Industry has firmly seized the opportunity of the implementation of the national new energy strategy, persisted in innovation, accelerated the development of the new energy battery foil industry, and became the top 10 supplier of battery factories in China, accounting for more than 30% of the domestic market share.

Anhui Suixi Meixin 72000 tons / year aluminum foil

Anhui Meixin Aluminum Co., Ltd., established in April 2011, is an enterprise producing high-precision aluminum strip products in Anhui Province. At present, the company has 4 melting and casting production lines and one cold rolling mill. The second phase of the project is under construction, and it is planned to add one cold rolling mill and five Ashenbach 1850mm aluminum foil mills. After the completion of the project, the production capacity will reach 80, 000 tons / year of high precision aluminum strip and 72000 tons / year of aluminum foil.

Suixi Li screen 20,000 tons / year battery foil

Anhui Liming New material Technology Co., Ltd. was put into production in June 2013, the main products are double zero aluminum foil and coated aluminum foil, the products are widely used in air conditioning and refrigeration, electronics and electrical appliances, communications, packaging and decoration, printing and other fields, with an annual production capacity of 60,000 tons / year. The company's current hydrophilic foil coating production line adopts new technology, and some special coated aluminum foils developed are deeply recognized by customers after they are put on the market. In 2019, the company produced 18000 tons per year, of which 3500 tons of digital battery foil with the thickness of 0.012mm was produced, and the product export business accounted for 30%. At present, the company's second phase of the project is under construction, and will re-invest in the construction of power battery foil, recycled aluminum cans and other projects.

Nantong starfish electronic 80000 tons / year electronic foil

On August 9, 2020, Nantong starfish Electronics Co., Ltd. successfully boarded the main board. It is stated in the prospectus that the stock raising funds will be used for the "low-pressure foil expansion technical renovation project", "medium-high pressure foil expansion technical transformation project", "low-pressure corrosion foil expansion technical transformation project" and "medium and high pressure corrosion foil expansion technical transformation project". Among them, the production capacity of foil for aluminum electrolytic capacitors is 80,000 tons / year.

Kunshan Aluminum Industry 8000 t / a Capacitor foil

Kunshan Aluminum Co., Ltd., founded in 2004, mainly produces double zero aluminum foil with a thickness of 4.5-12 μ m and a width of 110-1900mm. The products are widely used in packaging, capacitors and other fields. Aluminum foil production and sales volume of 35400 tons in 2017.

The company pays attention to intensive cultivation market segmentation, with domestic surface quality control technology and ultra-wide ultra-thin aluminum foil production technology, the production of aluminum foil large width 1900mm, thin to 4.5 μ m, good product quality, stable performance.

Medium-matrix composite electrical appliances and 40,000 tons / year battery foil

Jiangsu China Matrix Composite Co., Ltd., founded in 2004, is a chemical aluminum foil manufacturer controlled by Shantou Wanshun Co., Ltd. The company's products are mainly packaging aluminum foil, including aluminum foil for power capacitors, aluminum foil for lithium ion battery, aseptic packaging aluminum foil, etc. Next year, the production capacity of aluminum strip and aluminum foil of China Matrix Composite Co., Ltd. will reach 220000 tons and 210000 tons respectively, of which electronics and battery foil are more than 20, 000 tons per year.

Foshan Hi-Tech Foundation Co., Ltd. 20,000 tons / year electronic foil

21000 t / an aluminum foil production line of Nanshan Aluminum Calendering Co., Ltd.

Nanshan Aluminum holding subsidiary Aluminum Calendering Company has invested in the construction of 21000 tons / year aluminum foil production line project is expected to be put into production in early 2022.

South South Aluminum foil Co., Ltd. 20,000 tons / year double photovoltaic cell foil

On April 26th this year, 12 μ m hot-rolled 1100 dual-photovoltaic lithium battery foil was mass-produced in Guangxi Nannan Aluminum foil Co., Ltd., a subsidiary of South-South Aluminum Group. A few days ago, the company has achieved multi-batch supply of 12 μ m hot-rolled 1100 double photovoltaic battery foil to a number of domestic lithium battery manufacturing listed companies, with good feedback.

Dongxing of Jiuquan Iron and Steel Co., Ltd. supplies 1235 alloy battery foil strip roll in batch.

In May this year, 1235 battery aluminum foil produced by Tiancheng Color Aluminum Co., Ltd. of Dongxing Aluminum Industry of Jiuquan Iron and Steel Co., Ltd. was successfully supplied. 1235 battery aluminum foil products have a series of advantages, such as light weight, good coating, airtight, corrosion resistance, non-toxic and tasteless, etc., the main application fields are packaging, daily use, mechatronics, construction and so on.

Jiangsu Peixian Fengyuan Co., Ltd. 15000 tons / year electronic aluminum foil

Fengyuan Aluminum, founded in 2016, mainly produces aluminum foil with a thickness of 0.005-0.009mm for tobacco, food, pharmaceutical packaging and power capacitors. The company now has 5 aluminum foil mills, 2 coiling machines, 6 aluminum foil rewinding machines, 8 aluminum foil rewinding shears, 2 roll grinders, 24 aluminum foil annealing furnaces and 2 sets of whole oil recovery system.

Yunnan Haoxin Aluminum foil Co., Ltd. 35000 tons / year battery foil

On July 4, 2019, Yunnan Haoxin Aluminum foil Co., Ltd. relied on the ultra-thin aluminum foil production technology and invested 491 million yuan in the annual production of 35000 tons of aluminum foil for new energy power batteries. Haoxin Aluminum foil, formerly known as Yunnan Xinmei Aluminum foil Co., Ltd., was jointly invested by Yunnan Metallurgical Group, Alcoa and Yunnan Zhongyan material Group, and became a wholly owned subsidiary of Yunnan Aluminum Co., Ltd in 2015. Ultra-thin aluminum foil products are highly in line with the needs of European and American developed countries for capacitor miniaturization and lightweight. American GE (General Electric), Swiss ABB and other enterprises have long purchased Haoxin aluminum foil.

In January 2016, Haoxin aluminum foil set up a battery collector aluminum foil development project team, with the goal of developing a new aluminum alloy formula, exploring a set of technology that can produce a new type of lithium-ion battery current collector aluminum foil, and realizing the localization of the product. Based on the good market prospect, this product of Haoxin aluminum foil has attracted partners with strong advantages to participate in the development and production. With the promotion of the industrialization of this product, aluminum foil for current collector of 0.009mm double-sided photolithium ion battery has become another core product after ultra-thin aluminum foil.

In 2018, the production capacity of Haoxin aluminum foil is 15000 tons, and the annual production capacity of aluminum foil production line is 36000 tons. After the completion of the project of aluminum foil for energy and power batteries, the production capacity of the whole aluminum foil can reach 70, 000 tons per year.

The performance comparison between the 0.0045mm grade foil produced by Haoxin Co., Ltd. and the 0.005mm foil produced abroad is shown in the table.

Performance comparison of cast-rolled billet foil of Haoxin Company and hot-rolled billet foil abroad

Shandong Weihai Haixin new material 20,000 tons / year electronic foil

On November 25, 2018, in order to further extend the industrial chain and empower the development of enterprises, Weihai Haixin New Materials Co., Ltd. launched the construction of double zero aluminum foil project in 2018 and entered the trial production stage in 2020.

The project is a global production line using all the equipment of the German Ahenbach Company, and it is also a very special aluminum foil production line, mainly producing 0.005-0.026mm aluminum foil products. From the trial production, the thickness of the aluminum foil produced has achieved double zero, only 0.006mm, and the darkroom inspection pinhole (30-50) / m2 is far lower than the industry standard of (50,100) / m2. After the project reaches production, It can produce 70,000 tons of double zero aluminum foil per year, of which batteries and electronic foils are about 20,000 tons per year.

Battery foil production capacity of Xiashun Aluminum foil Co., Ltd. 20,000 tons / year

Founded in 1988, Xiashun aluminum foil has three production bases: Huli aluminum foil factory, Haicang aluminum foil factory and Haicang plate and strip factory, and has a complete aluminum plate, strip and foil industry chain from aluminum alloy melting and casting to hot rolling, cold rolling and foil rolling. The company has a global aluminum foil production line with a high installed level, with an annual production capacity of 220000 tons of aluminum strip and 120000 tons of aluminum foil. Among them, aluminum strip products mainly include high-precision aluminum foil billet and CTP base, and aluminum foil products are mainly 6-7 μ m aluminum foil. The output of electronic foil and battery foil of Xiashun Aluminum foil Co., Ltd. can reach 20,000 tons per year.

Anhui Huizhi Electric Transmission Technology Co., Ltd. 8000 tons / year electronic foil

Anhui Huizhi Electric Transmission Technology Co., Ltd. invested 100 million yuan in Anhui transmission equipment and accessories and electronic aluminum foil project to build 8000 tons / year electronic foil project in Suixi Economic Development Zone.

Jiangsu Yaming Aluminum Industry 10,000 tons / year electronic foil

Jiangsu Yaming Aluminum Co., Ltd. invested 200 million yuan to produce 10,000 tons of electronic aluminum foil in Huaibei aluminum base, which started in March 2019.

Shenlong Baoding New material Co., Ltd. 10,000 tons / year battery foil

Shenlong Baoding Company, built by Henan Shenhuo Group Co., Ltd., is a large aluminum foil enterprise built at one time in China, with a total production capacity of 105000 tons / year. Automatic pinhole inspection system, automatic surface defect monitoring system and automatic driving feeding system are installed in the cutting machine, which belongs to the aluminum foil industry.

10,000 tons of battery foil per year in Lanzhou Northwest Green Industrial Park

The project of the new green aluminum processing industrial park in the northwest of Lanzhou New area mainly produces single-zero foil and double-zero foil, which are mainly air-conditioning foil, household foil, pharmaceutical foil and battery foil, which was put into production in August this year. Among them, air conditioning foil 65000 tons / year, household foil 70, 000 tons / year, medicinal foil 13000 tons / year, battery foil 10, 000 tons / year, packaging double zero aluminum foil 20, 000 tons / year, wide single foil 20, 000 tons / year for other uses.

Mingtai aluminum 15000 tons / year electronic battery foil

Mingtai Aluminum Co., Ltd. has an annual production capacity of 100000 tons of high-precision aluminum foil and 1 million tons of plate and strip. In 2019, the flat-rolled aluminum products are 856000 tons, and the production and sales volume in 2021 is expected to exceed 1.2 million tons / year, making it a large single aluminum processing plant with more than 1 million tons / year of flat-rolled aluminum production and sales in the world.

Guizhou Chinalco Aluminum Co., Ltd. 8000 tons / year electronic foil

The 8000 t / an electronic foil project of Guizhou Chinalco Aluminum Co., Ltd. was basically completed in June 2014. Ten roll casting production lines and two cold rolling production lines have been put into use. The total investment of the project is about 850 million yuan, with a total construction area of 86000 m2, which is completed in two phases. The first phase will build 120000 tons of cast-rolled aluminum coil, and the second phase will build 108000 tons of cold-rolled aluminum foil billets and 40, 000 tons of aluminum foil products per year.

Shengtong 20,000 tons / year electronic battery foil

Shengtong Aluminum foil Co., Ltd. is a large double-zero aluminum foil enterprise built at one time in the world, with an aluminum foil production capacity of 200000 tons per year and electronic battery foil production capacity of 20, 000 tons per year. There are 16 domestic 4-high aluminum foil mills, including 2 for 1850mm and 14 for 2000mm. The cutting machine, roll grinder and automatic monitoring equipment of rolling process parameters of Shengtong Aluminum foil Company are all imported from Germany.

Nantong Zhaohe Electric Aluminum foil Co., Ltd. 12000 tons / year battery foil

The company, located in Nantong City, Jiangsu Province, is a wholly owned enterprise of, SDK), (Show Denko KK Industrial Co., Ltd., Showa Electric Co., Ltd., producing high-purity battery foil with an initial production capacity of 4800 tons / year. It began to expand the 7800 tons / year project in 2013 and was put into production in May 2015. the current production capacity is 12000 tons / year.

4.5 μ m capacitor foil of Jiangsu Daya Aluminum Co., Ltd.

Jiangsu Daya Aluminum Co., Ltd., located in Danyang City, uses casting-cold rolling strip to produce 4.5 μ m power capacitor foil in batch. it has been widely used in China in 2014 and exported to European ABB Company in 2015. Sales reached 300 tons in 2016, becoming one of the company's innovative products and one of the main products to open up the market. The thickness deviation of 4.5 μ m power capacitor foil is ±3%, and the number of pinholes is less than 5000 / m2. The company and the strip coil supplier have jointly developed three processes: the original aluminum ingot channel for fixed remelting, the fixed melting casting process, the fixed rail casting machine and its process, which ensures the quality, stability, consistency and traceability of the strip.

Anhui Zhongji Battery foil Technology Co., Ltd. 112000 tons / year high-precision electronic foil

The company, a subsidiary of Jiangsu China Matrix Composites Co., Ltd., began to build a 72000 ton / year high-precision electronic aluminum foil project on June 17 this year. The products are mainly used in the manufacture of battery electrodes and flexible packaging batteries, capacitor electrodes, printed circuit board substrates and other new electronic components. After completion, it will form a capacity of 112000 tons / year of electronic foil.

New fiber science and technology lithium electricity aluminum plastic film is put into production in the first phase.

On September 26th, 2018, the first phase of the Changzhou lithium battery aluminum plastic film project of Xinlun Technology was put into production, and the second phase of the project was put into production in March 2019. At that time, the monthly production capacity of the two major aluminum plastic film bases in Japan and Changzhou will reach 8 million m2, with an annual production capacity of more than 100 million m2. Xinlun Technology will become a large integrated service provider of flexible battery materials in the world.

Anhui Yaming Aluminum Technology Co., Ltd.

Invested by Jiangsu Nantong Yaguang Electronics Co., Ltd., the company mainly produces electrode foil for electrolytic capacitors. at present, it has 12 production lines, which can produce 1.6 million m2 electrode foil every month. 40 production lines are planned to be built in stages within 2 years, reaching a total production capacity of 15 million m2 a.

Daqing Yugang Longquan aluminum alloy processing material 20,000 tons / year electronic battery foil project

The project plans to invest about 33 billion yuan, and the production capacity of the first phase of the project will reach 200000 tons / year. The project is divided into three parts: plate and strip, extruded profile and intensive processing. The construction of the second phase of the project started in April 2020, with a production capacity of 500000 tons per year for extruded materials, 1.2 million tons per year for plate and strip in the third phase, and 20, 000 tons per year for electronic / battery foil. The plate, strip and foil project is scheduled to be put into production in 2023.

Chinalco has an annual production capacity of about 80,000 tons of electronic / battery aluminum foil.

Chinalco Group's Northeast Light Alloy Co., Ltd., Southwest Aluminum (Group) Co., Ltd., Northwest Aluminum Co., Ltd., Chinalco Henan Aluminum processing Co., Ltd., Chinalco Ruimin Aluminum Co., Ltd., etc., the total estimated production capacity of flat-rolled aluminum products has reached 3.1 million tons / year.

Chinalco Ruimin Aluminum Co., Ltd. is building a project of intensive aluminum processing base along the southeast coast of Chinalco in the new plant area of Fujian-Taiwan (Fuzhou) Blue Economic Industrial Park in Fuzhou New area, focusing on projects such as lightweight transportation, automobile plate and electronic aluminum.

Zhongwang Yingkou Strip Company and Tianjin Zhongwang Aluminum Co., Ltd. estimate 50,000 tons / year of electronic / battery foil production capacity

The plate and strip production capacity of Zhongwang Yingkou Company can reach 1.3 million-1.5 million tons per year. After October 2020, the hot test has been carried out one after another, and there are 10 irreversible 2350mm cold mills. Tianjin Zhongwang Aluminum Co., Ltd. was established in 2011, located in Wuqing District, Tianjin. The first phase covers an area of 6km2, with a production capacity of 1.8 million tons per year and an output of 488000 tons in 2019.

Changshan Aluminum Co., Ltd. 30,000 tons / year electronic / battery foil

Changshan Aluminum Industry Co., Ltd. is located in Changshu City, Jiangsu Province. The existing production capacity of plate, strip and foil is about 220000 tons / year, of which the production capacity of aluminum foil is about 180000 tons / year, and that of electronic / battery aluminum foil is estimated to be about 30 000 tons / year.

Electrolytic capacitor

Electrolytic capacitor is one of the important products of electronic components. The main advantages of aluminum electrolytic capacitor are high specific capacitance, small volume, light weight and reasonable cost. As positive and negative electrodes of electrolytic capacitors, it accounts for about 70% of the production cost of electrolytic capacitors. The structure of the electrolytic capacitor is composed of electrode lead, aluminum shell and core, which is the key component, which is composed of anode foil, electrolytic paper and cathode foil, and the electrolyte is wrapped in the middle. In recent years, great progress has been made in the field of aluminum foil for electrolytic capacitors. Many achievements have been made in the research and development of pure aluminum, AI-Mn alloy, AI-Cu alloy, AI-Mg alloy and so on. A series of products suitable for different markets have been launched.

In the electrolytic capacitor, the cathode foil is the leading electrode, and the larger its specific surface area is, the higher the specific capacitance of the capacitor is. There are a large number of Al6Mn, AI (Fe,Mn) Si and Mg2Si particles scattered in the 3003 aluminum alloy foil matrix, whose corrosion potential is different from that of the aluminum matrix, forming a small corrosion in-situ battery, which will form a large number of spongy corrosion pits and increase the specific surface area, thus becoming a widely used cathode foil material.

Control of impurities in 3003 alloy cathode foil

During electrochemical corrosion, the increase of aluminum foil surface area has a great influence on the specific capacitance of aluminum foil. therefore, the type and distribution of trace impurity elements have a significant impact on the corrosion process and specific capacitance of aluminum foil. For 3003 alloy cathode foil, the impurity elements and alloy elements Mn should be controlled reasonably, such as Cu, Fe, Si, Mg, Ti and so on.

Mn: increases the recrystallization temperature of aluminum, and the formed Al6Mn can refine the recrystallized grains of the alloy. The electrode potential of Al6Mn is almost equal to that of pure aluminum, so it has no effect on the corrosion resistance of aluminum foil. The solid solubility of Mn in aluminum is very low, which is almost zero at room temperature. it is mainly distributed in the matrix in the form of Al6Mn phase, forming corrosion core. Mn also has a strengthening effect, so with the increase of Mn content, the strength of the foil increases, but if the Mn content is too high, it will precipitate coarse AI6Mn phase, resulting in non-uniform corrosion.

The electrode potential of Cu: copper is higher than that of aluminum matrix, the solid solution of Cu and precipitated Al2Cu compounds will become the corrosion center, and Cu also has a strengthening effect. However, the content of Cu in the alloy still needs to be controlled. if the content of Cu is too high, it is easy to produce coarse corrosion pits in the matrix, resulting in excessive corrosion, which will adversely affect the specific capacitance of the product. When the content of Cu is moderate (0.05%-0.2%wt), the pitting corrosion is very uniform, and the Cu element can reduce the potential difference between the grain and the grain boundary, which can restrain the trend of intergranular cracking and improve the stress corrosion resistance of the alloy.

Fe: forms Al6 (Fe,Mn) phase in the matrix, which can reduce the uneven grain size distribution caused by Mn element segregation to a certain extent, but Fe element will produce FeAl3 cathode phase, which will affect the corrosion performance and lead to non-uniform corrosion.

Mg:Mg helps to increase the corrosion rate, but too high content will lead to aluminum tube cracking, so it is also necessary to control the content. In addition, B, Tl, Cr, Zr, Zn, Sc and other elements will improve the corrosion resistance of the alloy and affect the corrosion of cathode copper, so the content should be strictly controlled.

Casting

The traditional cathode foil and the cathode foil produced abroad are produced with ingot-cold rolled strip, but at present, more than 75% of the cathode foil produced in China is produced from cast-rolled strip. Production process of casting-rolling coil: furnace preparation, charging, melting, stirring and slagging, adjusting composition, internal treatment (secondary refining), converter and static (second refining) "degassing box degassing and slag removal" filter box dual-channel two-stage ceramic filter plate Filter slag removal casting.

In the process of roll-casting, the hydrogen content, inclusion, compound and composition segregation of the melt are important factors for the defects of the cathode foil, which directly affect the number and size of pinholes in the cast-rolling billet, therefore, appropriate and effective purification of aluminum melt. Filter and other measures are the key to reduce such defects.

The speed of the rotor should also be strictly controlled and the rotational speed should not be less than 200r/min to avoid being out of place. After degassing and slag removal, the hydrogen content should not exceed 0.12ml and 100gAl, and the filtration rate of inclusions ≥ 20 μ m should be more than 60%. The commonly used grain refiner in the roll casting process is aluminum titanium boron wire (AITi5B), but when the Ti content is higher than 0.05%, it is easy to produce coarse and hard compound Ti2B, which is easy to form pinholes. Therefore, it is very important to reduce the content of Ti. Because of the timeliness of Al-Ti-B wire, the melt crystallization refinement effect of adding 10min is better, if it is more than half an hour, the grain refinement effect will be greatly weakened.

Heat treatment

If the content of trace impurity elements in 3003 alloy is high, it will promote the corrosion of aluminum atoms near the surface defects and produce dense corrosion holes. When the trace elements are uniformly distributed, the pores will also be uniformly distributed, so that the specific capacitance of the aluminum foil increases obviously. The appropriate annealing process can promote the trace elements in the material to quickly move closer to the equilibrium concentration, and make these elements uniformly distributed. It can obviously segregate the Mn in the casting billet, and can make the second phase particles fine and dispersed, and improve the specific capacitance of the cathode foil.

The effect of homogenization annealing on its microstructure will also be inherited to the microstructure and properties of annealed foil, so homogenization annealing is the key process to improve the quality of cathode foil.

Recrystallization annealing is also an important means to improve cathode foil effectively. In the foil rolling stage, large grains are easy to form coarse fibrous structure, which can easily lead to delamination corrosion and make the material thinner. This will cause part of the spongy corrosion layer to be delaminated and dissolved, resulting in a decrease in the specific capacitance of the material and affecting the performance of the material. Rapid recrystallization annealing is suitable for the production of cathode foil, which can increase the number of recrystallization nucleation, prevent the formation of coarse grains and promote the improvement of specific capacitance. In addition, the relationship between the cold working rate and the specific capacitance after intermediate annealing is nonlinear, and the specific capacitance of the material increases obviously when the processing rate is more than 90%.

Development of battery aluminum foil abroad

Like China, the production and sales of battery aluminum foil in foreign developed countries have entered the stage of rapid growth.

Global electric vehicle sales rose 160% in the first half of this year compared with the same period last year.

Global electric vehicle sales rose 160 per cent year-on-year to 2.6 million in the first half of this year, according to Canaris, a consultancy in Spain. The increase in electric vehicle sales outpaced the overall growth in the global car market, which was 26 per cent. Norway is still the country where electric cars account for a high proportion of new car sales, accounting for more than 80%. Automobile companies are expanding their electric vehicle production lines to provide consumers with more choices. The European Union has set carbon emissions targets for automakers. European countries have introduced consumer incentives and set a goal of banning the sale of cars with internal combustion engines. The challenge for carmakers is to keep up with demand for electric cars in the midst of a parts shortage crisis.

China is still the largest electric car market, with 1.1 million units sold in the first half of the year, accounting for 12 per cent of total sales. Only 6% of cars sold in mainland China in 2020 are electric vehicles, and that proportion will more than double for the whole of 2021. The successful landing of Tesla's project in China has prompted Chinese automakers to expand their electric vehicle business. Ian, BYD, ideal, Lulai and Xiaopeng and other brands of electric vehicles.

Toyota of Japan makes great efforts to develop on-board batteries

Japan's Toyota Motor Co., Ltd. recently announced that it will invest 1.5 trillion yen to develop and increase production of on-board batteries by 2030. Vehicle battery is the core component of electric vehicles such as electric vehicle (EV) and hybrid electric vehicle (HV). At present, the automobile industry is speeding up the process of electrification transformation in order to realize decarbonization. Regarding the stable supply of batteries and low cost as key factors, Toyota is speeding up the construction of the relevant system.

According to the new plan, 1 trillion yen, which accounts for 2/3 of Toyota's total investment, will be used to expand battery capacity. Toyota plans to periodically expand the number of battery production lines needed for EV such as lithium batteries to about 70, 35 times the current number. Batteries account for about 30% of the production cost of each EV, and Toyota aims to halve battery costs by 2025. To this end, Toyota will promote the integrated development of battery and EV, including the development of cheap battery materials and reducing current loss.

Toyota plans to increase its total sales of electric vehicles, including the HV and the plug-in hybrid, to 8 million by 2030, about four times as many as today, including 2 million EV and fuel-cell (FCV), which requires more batteries than pure electric vehicles. HV needs more batteries than pure electric cars. Batteries determine the performance of electric vehicles, if you can not rely on their own power to ensure battery technology and capacity, batteries will be more and more difficult to obtain. Therefore, Toyota is determined to make its own batteries, improve its research and development capacity, and step up the development of new batteries that do not use metal as raw materials.

EU bans the sale of fuel vehicles in 2035

The European Union says it will ban the sale of models such as fuel cars in 2035. Compared with other regions, Europe takes the lead in promoting the electric transformation of fuel vehicles, hoping to establish its dominant position in the automobile industry. Volkswagen will switch to EV, and Volkswagen will stop producing fuel cars in Europe between 2033 and 2035. The price of the small EV "ID.LIFE" released by Volkswagen is more than 30% lower than that of its existing main models. Mercedes-Benz has decided to make the transition to EV, and what it needs to do now is to accelerate its implementation. Volkswagen and Daimler began to reshuffle their personnel at the factory in order to promote the electrified transformation of cars. The German government has also set up a "future fund" with a total amount of about 1 billion euros to support the structural transformation of the automobile industry. In July 2021, the European Commission introduced a bill banning the sale of fuel vehicles and hybrid cars in 2035. Carbon dioxide emissions in 2030 will also be subject to stricter restrictions. The purpose of the EU is not only to "decarbonize", but also to gain an advantage in the development competition of the future main model EV.

Battery recycling

In order to achieve the goal of "double carbon", the world is increasing the use of new energy electric vehicles, but the recycling of scrapped batteries is an urgent environmental and economic problem to be solved. The European Union hopes to have 30 million electric vehicles on European roads by 2030. At that time, how to deal with the obsolete electric vehicle battery will be a great challenge, because a new product has never been developed at such a fast speed and scale, and after 10-15 years, a large number of electric vehicle batteries will be obsolete. How to disassemble and recycle its useful materials is very important and urgent.

Although most electric vehicles are more or less the same as traditional car structures, the big difference is the battery. Traditional lead-acid batteries can be widely and fully recycled, but lithium-ion batteries used in new energy electric vehicles are not convenient to do so. The batteries of electric vehicles are larger and heavier than those of ordinary fossil fuel vehicles and are made up of hundreds of individual lithium-ion batteries that are carefully disassembled one by one to prevent explosion. The European Union recently expressed the hope that electric car suppliers will be responsible for ensuring that their products are not simply discarded after phase-out, and some carmakers have begun to respond, such as Nissan Leaf, which reuses its old batteries for automatic guided vehicles. deliver parts in the workshop. Volkswagen is doing the same, building a recycling plant in Salzjit, Germany, and plans to recycle 3600 electric vehicle battery systems a year at a pilot plant.

However, the current recycling efficiency is not high, most of the materials in the battery are reduced to the so-called "black matter" in the recycling process, that is, the mixture of Li, Mn, Co and Ni, which requires further energy-intensive processing before the materials can be recycled into usable forms. Faraday Research Institute in the UK and others are developing new processes for battery recycling and optimizing the recycling process, and there will be a more and more cost-effective battery recycling industry for electric vehicles in the future.

Disassembling the battery by hand can make more materials be recycled effectively, but it will give rise to many new problems, such as environmental protection, high labor cost and economic problems. It is difficult to form a market with good economic benefits in economically developed countries. The best solution to this problem is automation and robotics. If automation can be realized, most of the harm of battery recycling in electric vehicles can be reduced and the economic benefit can be improved.

Research and development of new battery materials

At present, the main raw materials in vehicle lithium batteries are lithium and cobalt in addition to aluminum as electrodes. This year, the price of lithium carbonate has risen to 100000 yuan per ton, more than double that of a year ago. To replace lithium batteries, battery scientists are looking for lithium Substitute, the first to bear the brunt is sodium, because the physical and chemical properties of sodium are close to lithium. China Ningde Times New Energy Technology Co., Ltd. plans to commercialize sodium batteries in 2023. The great advantage of replacing lithium with sodium is that sodium is rich in resources, and there is plenty of sodium in sea water, which is inexhaustible and inexhaustible. In addition, the performance of sodium battery is also higher than that of lithium battery.

Concluding remarks

China's automotive lithium-ion batteries have entered a period of rapid development since 2016, at least until 2035. The aluminum foil production capacity of power batteries that have been put into production and under construction is sufficient to meet the needs of new energy vehicle battery manufacturing. In the future, the main task of the aluminum industry is not only to fill up and build the necessary projects for the shortcomings of the existing battery aluminum foil production line, but also to strengthen research and development and develop new battery aluminum foil alloys, the alloys currently used are all traditional alloys. There is nothing new, of course, in the chemical composition control has also done a lot of work, achievements.

In addition, according to statistics, China has a lot of intellectual property rights on lithium-ion batteries and materials, but there are few inventions in principle, most of which are "improved" inventions, especially battery materials, so we should make more efforts in these aspects. strive to become a leader in power batteries in all aspects.