Unlike the hot car sales in previous years, this year’s car market seems to be particularly early. According to the data of the Association, the retail sales of narrow-seat passenger cars in China was 1,904,525 vehicles in September this year, down 13.2% year-on-year. The decline continued to expand to double digits; the cumulative sales of narrow-seat passenger cars in January-September totaled 6,684,812. The year-on-year growth rate was -0.6%, and there was a rare cumulative year-on-year negative growth. The auto market has experienced a year-on-year decline in sales growth for three consecutive months, dropping to the “freezing point” in the past seven years. However, in the global environment of the automobile market full of chilly and chilly, the new energy vehicle market is in the ascendant, and the growth rate of new energy vehicle sales is unique, attracting major auto giants to increase the layout. The industry believes that new energy vehicles will welcome global heavy volume. With the opening of new energy vehicles, companies and investment groups from all walks of life are willing to enter this capital. Nanshan Aluminum also took the lead in entering the market by taking advantage of the new energy vehicle. On September 6-7, 2018, SMM held the “2018 China Aluminum & Silicon Processing Industry Chain Supply and Demand Trading Summit”. The representative from Nanshan Aluminum Industry conducted a thorough analysis of the current status and development trend of battery aluminum foil, in addition to Nanshan. Aluminium’s leading technology and management experience in the industry also gave a wonderful speech on the future trend of battery aluminum foil.

 

The aluminum foil industry generally refers to battery aluminum foil as battery foil. Since 2015, the rapid development of the power battery industry is the trigger for the development of the battery foil boom in the aluminum foil industry. In just three years, the number of domestic battery foil manufacturers has rapidly increased from four to five to more than a dozen. Aluminium foil products have grown so rapidly in China.

 

According to lithium ion battery use classification: power battery foil, consumer battery foil, energy storage battery foil. At present, the largest demand is power battery foil, accounting for about 50% to 55%. The consumer battery market is basically saturated. The demand for power battery foil will increase further in the future. The energy storage battery foil will gradually increase its power, so the battery foil market is still There is room for growth.

 

Key quality requirements for battery aluminum foil

  1. Mechanical properties:

Battery foil customers generally pay attention to the mechanical properties first. Different customers have different requirements on mechanical properties. Most customers want high tensile strength and high elongation. The mechanical properties mainly depend on the design of the chemical composition and the billet production process. It is possible to design a battery foil with various mechanical properties using an alloy grade.

 

2, thickness and areal density

The thickness and the areal density have an impact on the uniformity of the customer’s carbon coating and coating of the positive electrode material. The mainstream customers focus on the single roll thickness/density density fluctuation, batch thickness/area density fluctuation, and customers will pay attention to CPK, PPK, etc. Process capability indicators. The thickness is mainly influenced by the billet and the rolling mill, and the high-precision, state-stabilized mill can bring about the desired thickness level.

3, surface wetting tension

The surface wetting tension of the battery foil affects the quality of the carbon coated and coated positive electrode material. The low surface wetting tension usually leads to defects such as leakage coating, poor coating, and shrinkage of the edge of the coating material, but some customers do not The surface wetting tension is defined and is known to be different from the slurry or coating process. The surface wetting tension is affected by factors such as the amount of oil in the aluminum foil, the quality of the rolling oil, additives, etc., which is a headache.

4, pinhole

The pinholes that lithium-ion customers pay attention to are mainly distribution and size, followed by quantity. Generally, the diameter is not more than 300μm or 500μm, there is no large pinhole near the edge, and there is no periodicity, line or dense pinhole. The number of pinholes of the 12μm battery foil is generally not more than 10/m2. Hot-rolled aluminum foil can basically meet these requirements, and cast aluminum foil has a little difficulty in stability.

5, the shape quality

Battery foil shape quality test method: The amount of collapse and the degree of collapse are usually tested after applying tension, and some customers use offline shape detection equipment to quantify. As we all know, the linear shape and off-line shape of aluminum foil are not exactly the same. The final shape quality depends on the shape of the aluminum foil blank, equipment level, process parameters and operator level. The first three factors can be controlled by the system, so the operation The level of personnel is crucial.

  1. Other quality requirements Compared with traditional aluminum foil products, the application of battery foil involves safety. Therefore, the requirements for cutting quality such as trimming burrs and aluminum powder are becoming more and more strict. In addition, the quality points such as dark surface highlights, surface pits, and surface oil stains are not negligible.

The dark spot highlights only appear on single-sided photocell foils, which is also an aspect of the increased share of double-sided photocell foils in the battery foil market.

 

Battery aluminum foil quality and production difficulties

1, high strength

At present, the tensile strength is generally required to be 200 MPa or more, and each aluminum foil enterprise can basically supply in batch or small batch. Some customers require a tensile strength of 250 MPa or more. This battery foil is difficult to mass-produce and has a low yield. There are also some customers who require 280 MPa and 300 MPa or more, and have basically reached the rolling hardening limit of aluminum foil products (10μm~15μm thickness). They can be developed domestically, but it seems that there is no mass production. Only domestic production, domestic lithium battery customers are known. I have purchased it from Japan.

2, thickness reduction and strict tolerance

Thinning: Since 2016, many customers have started to have 9μm and 10μm double-sided light. This has exceeded the theoretical limit of single-sheet aluminum foil rolling. We can barely supply, but the yield is low and painful. Thickness tolerance: ±2% of existing customer requirements, even if the equipment accuracy is very high, it is difficult to meet this requirement, because it involves the horizontal and vertical thickness uniformity of the hot rolling, cold rolling and foil rolling processes, and equipment And the stability of personnel operations.

3, wide and plate shape

In order to improve production efficiency, lithium battery customers have generally increased the wide production line, the demand is 700mm~800mm width, and even more than 1000mm, which is a very big challenge for aluminum foil enterprises. Our equipment capacity can be 1700, 1800, 2000mm width, why not want to roll around 1600mm to cut the width of 700mm~800mm, the only reason is the shape quality. For the battery foil with ultra-high tensile strength, the degree of work hardening is high, the shape control is extremely difficult, and the shape quality will be the biggest problem that is difficult to mass-produce.

4, the system, packaging methods, etc. are complex

Power battery foil involves the automotive industry. The ITAF 16949 is a basic requirement. The system requires too much content and requires a professional team to implement it. The requirements of different customers for packaging methods are also very different. In fact, the cost of aluminum foil packaging is very high. 5, surface wetting tension

Surface wetting tension often has instability problems in production, and it needs to be improved by various means. According to the information exchanged with the same industry, the means to increase the surface wetting tension is basically the same.

 

Difficulties faced by aluminum foil companies

  1. Customer requirements are getting higher and higher, complaint rate is high

At present, customers’ requirements for thickness, tensile strength and shape have reached the limit of aluminum foil equipment and production, and it is almost impossible to improve. The requirements for surface quality, pinhole and slitting quality are also getting higher and higher. This will inevitably lead to an increase in production costs, a decline in the yield, and an increase in the complaint rate.

2, a variety of battery foils, a small amount of single specifications

According to the network data, it is estimated that the demand for battery foil in China will reach 30,000 to 40,000 tons in 2020. It seems that the quantity is considerable, but there are too many requirements for alloy, thickness, width and mechanical properties, and the number of dispersion to a single specification is very small. At present, the battery foil produced by Nanshan is mainly made of 1100 and 1060 alloys, with nearly 10 kinds of thickness. The width and length of the coil are more complicated. Now, the output of several hundred tons per month is required to prepare several times of blanks. Even if this is not enough, the customer will not be fully satisfied. Increased special needs.

  1. Industry competition is intensifying, processing fees are decreasing year by year, and research and development of new products maintains advantages.

As more and more aluminum foil companies begin to produce battery foils, market competition has intensified; coupled with the transfer of pressure from lithium battery customers, the price of battery foils has also been declining year by year. In order to maintain the market advantage in the future, we only have to constantly develop new products to meet the requirements of new and old customers, but this new requirement generally has only one demand direction, which may take 1-2 years to be finalized. The battery foil research and development investment is huge, which requires enterprises to have Strong strength and firm determination.