Adtech degassing unit and ceramic foam filter helps to produce higher specification aluminum foil for lithium batteries

Aluminum foil is a key material in the cathode of lithium batteries.

According to CNKI statistics, the consumption of aluminum foil for a 1GWh lithium battery is about 600-800 tons. Statistics from the Research Department of the Power Battery Application Branch show that in 2018, the total installed capacity of new energy vehicle power batteries in my country was 56.89GWh, and the corresponding aluminum foil consumption was about 34,000-46,000 tons. With the rapid development of the lithium battery market, the industry expects that the consumption of aluminum foil for lithium batteries will reach about 80,000 tons by 2020.

It is understood that lithium battery aluminum foil can be divided into power battery foil, consumer battery foil, and energy storage battery foil. Among them, power battery foil currently has the largest demand, accounting for more than 50%, while the consumer battery aluminum foil market is basically saturated. Industry analysts believe that the demand for power battery aluminum foil will further increase in the future, and energy storage battery aluminum foil will gradually exert its strength.

A few days ago, Nanshan Aluminum announced that the company's holding subsidiary, Aluminum Rolling Company, plans to invest in the construction of a high-performance high-end aluminum foil production line project with a total investment of 453 million yuan. Digital consumer battery foil 16,800 tons.

It is reported that another aluminum foil giant, Dongguang Sunshine Technology Co., Ltd., launched the construction of the third phase of the Ruyuan Foil Factory this year, building a new material project with an annual output of 40,000 tons of high-precision aluminum foil, mainly producing battery aluminum foil for new energy vehicles. After it is completed and put into operation, Ruyuan Fine Foil can reach an annual production capacity of 120,000 tons of high-end aluminum foil.

Earlier, TOKYO said that it intends to strengthen cooperation with UACJ, the largest aluminum foil manufacturer in Japan, and the joint venture company Ruyuan Fine Foil will invest no more than 600 million yuan in the construction of aluminum foil for lithium batteries and other projects.

Due to the optimistic market prospects of lithium battery aluminum foil, Dingsheng New Materials, a leading enterprise in the domestic aluminum foil industry and mainly engaged in air-conditioning aluminum foil and other businesses will also focus on the lithium battery field. As early as last year, Dingsheng New Materials disclosed in its prospectus that about 600 million yuan of funds to be raised in the IPO will be used for the aluminum alloy foil project for power battery electrodes. The company will add an annual output of 40,000 tons of battery light foil production lines. And an annual output of 10,000 tons of battery coating foil production line.

Previously, Mingtai Aluminum stated on the interactive platform that the company's battery foil and electronic foil accounted for more than 20% of all aluminum foil products, and it was increasing year by year. In 2018, the company's aluminum foil production and sales volume is expected to reach 100,000 tons.

It is understood that the production of lithium battery aluminum foil requires top technology. When absorbing the positive and negative electrode materials of the battery, only one fragmentation is allowed to reach 10,000 meters, because if the entire lithium battery production line is fragmented, all products will be scrapped. Dare to produce, lithium battery companies do not dare to use.

At present, the overall level of technology and technical equipment of the domestic battery aluminum foil processing industry still lags behind the international advanced level. Due to high technical barriers, the current global power lithium battery aluminum foil manufacturers are mainly concentrated in Japan and South Korea, mainly Japan's Toyo Aluminum and Hitachi Metals.

It is understood that in addition to Nanshan Aluminum, Dongguang Technology, Dingsheng New Materials, and Mingtai Aluminum(Mingtai Aluminum using Adtech's degassing units, ceramic foam filters, and caster tips.), there are also Yongjie New Materials(Yongjie new materials' 15 production lines are made in Adtech, such as degassing units, ceramic foam filters, and caster tips.), Fulaishun, Hangzhou Five Star, Huaxi Aluminum, Sifangda, Zhongnan Aluminum, Shanghai Alcoa, as well as aluminum foil suppliers such as Zhenxin Foil Electronics, and only a few manufacturers have high technical indicators.

In recent years, with the rapid development of lithium battery technology, lithium battery aluminum foil has been reduced from 16um in previous years to 14um, and then to 12um. Now many battery manufacturers have mass-produced 10um aluminum foil.

It is reported that Nanshan Aluminum has achieved a batch supply of 12μm thickness battery foil, and is developing 10-9μm products. For light and thin aluminum foil, domestic enterprises still mainly import from Japan, South Korea, Germany, and other countries, and there are few domestic enterprises that can produce it. Once it is successfully put into production, it will have the advantage of import substitution.

Why use aluminum foil for the positive electrode of lithium-ion batteries and copper foil for the negative electrode? There are three reasons:

First, copper and aluminum foil has good conductivity, soft texture, and low price. We all know that the working principle of lithium batteries is an electrochemical device that converts chemical energy into electrical energy. In this process, we need a medium to transfer the electrical energy converted from chemical energy, and conductive materials are needed here. Among ordinary materials, metal materials are the most conductive materials, and among metal materials, copper foil and aluminum foil are cheap and have good conductivity. At the same time, in the lithium battery, we mainly have two processing methods: winding and lamination. Compared with winding, the pole piece used to prepare the battery needs to have a certain degree of flexibility to ensure that the pole piece does not have problems such as brittle fracture during winding. Among metal materials, copper and aluminum foil is also soft metal. Finally, consider the cost of battery preparation. Relatively speaking, the price of copper and aluminum foil is relatively cheap, and there are abundant resources of copper and aluminum elements in the world.

Second, copper and aluminum foil is relatively stable in the air. Aluminum easily reacts with oxygen in the air, forming a dense oxide film on the surface of the aluminum to prevent further reaction of aluminum, and this thin oxide film also has a certain protective effect on aluminum in the electrolyte. Copper itself is relatively stable in air and basically does not react in dry air.

The third is that the potential of the positive and negative electrodes of the lithium battery determines the use of aluminum foil for the positive electrode and copper foil for the negative electrode, not the other way around. The positive electrode potential is high, and the copper foil is easily oxidized at high potential, while the oxidation potential of aluminum is high, and the surface of the aluminum foil has a dense oxide film, which also has a good protective effect on the internal aluminum.

For lithium-ion batteries, the commonly used positive current collector is aluminum foil, and the negative electrode current collector is copper foil. In order to ensure the stability of the current collector inside the battery, the purity of both is required to be above 98%. With the continuous development of lithium battery technology, whether it is a lithium battery for digital products or a battery for electric vehicles, we all hope that the energy density of the battery is as high as possible, and the weight of the battery is getting lighter and lighter, and the most important thing in the current collector is Reducing the thickness and weight of the current collector intuitively reduces the volume and weight of the battery.

Thickness requirements of copper and aluminum foil for lithium batteries

With the rapid development of lithium batteries in recent years, the current collectors for lithium batteries have also developed rapidly. The positive aluminum foil has been reduced from 16um in previous years to 14um, and then to 12um. Now many battery manufacturers have mass-produced aluminum foil that uses 10um, and even uses 8um. As for the copper foil for the negative electrode, due to its good flexibility, the thickness of the copper foil has been reduced from the previous 12um to 10um, and then to 8um. At present, most battery manufacturers use 6um for mass production, and some manufacturers are developing 5um/4um are all possible. Since lithium batteries have high requirements for the purity of copper and aluminum foil used, the density of materials is basically the same level. As the thickness of the development decreases, the areal density also decreases accordingly, and the weight of the battery is naturally getting smaller and smaller, which is in line with our requirements for lithium batteries. need.

Surface roughness requirements of copper and aluminum foil for lithium batteries

For the current collector, in addition to the influence of its thickness and weight on the lithium battery, the surface properties of the current collector also have a great influence on the production and performance of the battery. Especially for the negative electrode current collector, due to the defects of the preparation technology, the copper foils on the market are mainly single-sided wool, double-sided wool, and double-sided roughened varieties. The asymmetry of the two-sided structure leads to asymmetric contact resistance of the coating on both sides of the negative electrode, which in turn makes the capacity of the negative electrode on both sides unable to be released uniformly; at the same time, the asymmetry of the two sides also leads to inconsistent bonding strength of the negative electrode coating, and yes, the charge-discharge cycle life of the negative electrode coating on both sides Serious imbalance, which in turn accelerates the decay of battery capacity.