The safety of lithium batteries has always been a concern of people. Recently, the composite current collector, which can provide higher safety performance for lithium batteries, has spread the news of industrialization acceleration.

The current collector is a key component in lithium batteries, which mainly serves as a carrier of electrode materials to collect the current generated during battery charging and discharging and transmit it to external circuits. It is usually located in the positive and negative electrode structure of the battery, and is tightly bound to the active material (e.g. oxide at the positive electrode, graphite at the negative electrode). While the traditional current collector is dominated by a single metal, the new composite current collector optimizes weight, safety and performance.

Composite current collector equipment manufacturer Dongwei Technology (688700.HK) SH, share price of 43.9 yuan, market value of 13.1 billion yuan) share price rose for many days, rising by more than 18% on March 13, and finally closed at 43.90 yuan per share on the same day, up 7.13%. In addition, composite current collector manufacturer Baoming Technology (002992. SZ), British Union (002846. SZ) shares also rose.

On the news side, there is research report information that the composite current collector industry may start a new round of capital expenditure in the second quarter of 2025.

However, the relevant staff of Ruipu Lanjun, a power battery and energy storage battery manufacturer, replied to the reporter of "Daily Economic News": "There is no large-scale application at this stage. "[Composite current collectors] have certain advantages, but also obvious disadvantages, such as complex processes, high costs and poor consistency," he added. ”

The "bodyguard" of battery safety

According to the research report of Zheshang Securities, the composite current collector is a new type of lithium battery material with a sandwich structure of "metal conductive layer - PET/PP and other polymer material support layer - metal conductive layer", which aims to improve battery safety and energy density.

Zhu Zhixiang, a researcher at Xinchun Information, told the reporter of "Daily Economic News": "The main advantage of the composite current collector is in safety, due to its unique 'sandwich' structure, the polymer material layer on both sides is PET (polyethylene terephthalate), PP (polypropylene), and has excellent insulation performance. In the puncture test, the burr generated by the composite current collector is smaller, and the insulating layer formed by the polymer material will have a breaking effect, which can effectively control the short-circuit current and not increase, so as to reduce the risk of thermal runaway. ”

It can be seen that the composite current collector can effectively improve the safety of the battery, which can be described as the "bodyguard" of battery safety.

In addition to improving battery safety, the composite current collector also helps to improve the energy density of the battery. Zhu Zhixiang said: "In terms of performance, the performance of composite copper foil and composite aluminum foil is different. Taking 1+4.5+1μm (micron) composite copper foil as an example, the energy density of composite copper foil is increased by 5%~10%, and the material cost is saved by more than 60% compared with traditional 6μm copper foil. Taking 2+4+2μm composite aluminum foil as an example, the use of composite aluminum foil can improve the energy density by 2%~10%, and the material cost is more than 50% less than that of traditional 12μm aluminum foil. ”

In terms of the industrial chain, Dongwei Technology's investor relations activity record sheet on January 9, 2025 shows that from the company's layout of composite copper foil electroplating equipment in 2017, to the sale of the first drum conductive electroplating in 2021, to the large-scale sales of bilateral water plating equipment for technical upgrades in 2022, and the current R&D and manufacturing of wide bilateral water plating equipment, the speed and stability of the equipment have been continuously improved.

In addition, according to the record of investor relations activities of British Union Co., Ltd. on December 24, 2024, the company will invest in the construction of new energy power lithium battery composite aluminum foil and composite copper foil project in 2022, with a total investment of 3.089 billion yuan, and plans to build 10 composite aluminum foil and 134 composite copper foil production lines, with an annual production capacity of 100 million square meters of composite aluminum foil and 500 million square meters of composite copper foil after reaching production. At present, 5 Japanese ULVAC composite aluminum foil production lines have been built. In terms of composite copper foil, 5 composite copper foil production lines have been built, and the follow-up production lines are still under construction in an orderly manner.

In addition, U&S ENERGY, A KOREAN CUSTOMER, PLANS TO PURCHASE 2 MILLION SQUARE METERS OF COMPOSITE ALUMINUM FOIL AND 1 MILLION SQUARE METERS OF COMPOSITE COPPER FOIL FROM JIANGSU YINGLIAN (A SUBSIDIARY OF YINGLIAN CO., LTD.) IN 2025. U&S ENERGY serves leading new energy companies such as Samsung, SDI, LG, SK On and so on.

"False fire" or dawn?

As for whether the composite current collector manufacturer has started large-scale capital expenditure, the reporter of "Daily Economic News" called Dongwei Technology on the afternoon of March 13, but could not get through. The reporter then called Baoming Technology, and its staff said: "This involves inside information, and (I) am not responsible for this project." ”

Zheshang Securities believes that in 2025, composite aluminum foil may move towards larger-scale mass production, and at the same time, composite copper foil may make a breakthrough in the terminal application market.

In terms of composite aluminum foil, the current evaporation equipment manufacturers mainly include Japanese Airvac and a number of domestic coating manufacturers. In terms of domestic material manufacturers, such as Yinglian Co., Ltd., it has reached a strategic cooperation with Japan's ULVAC to purchase its composite aluminum foil production line. In addition, the localization of evaporation equipment will help to further reduce the cost of composite aluminum foil in the future.

In terms of composite copper foil, the composite copper foil process is highly complex, and the mainstream of the industry adopts the two-step process of "magnetron sputtering + water electroplating", and has formed a number of domestic equipment manufacturers represented by Dongwei Technology, Tengsheng Technology, Huicheng Vacuum, etc., with a certain scale of equipment production capacity.

Regarding the mass production yield of composite current collectors, Zhu Zhixiang said: "At present, the yield rate of composite current collectors of leading manufacturers can be controlled at about 80%, and the yield rate of the second echelon is only about 60%. Overall, the yield is at a low level, so the production cost of composite current collectors is high. ”

It specifically stated: "Composite aluminum foil due to the production process (one-step evaporation) is relatively simple, last year has been the first to introduce and load, but the composite aluminum foil process cost accounted for nearly 9 percent, the main equipment is imported from Japan Alphabet, the equipment localization process is slow, and the production cost is difficult to drop significantly in the short term." The technical difficulties in the production process of composite copper foil batteries mainly include the adjustment of the rolling welding process, the adjustment of the cold pressure and the upturning in the coating process, and the localization rate of key equipment (such as ultrasonic rolling welding equipment) is relatively high. When the yield reaches more than 95%, the composite copper foil current collector will reduce the cost by 20~30% compared with the traditional current collector. ”

It can be seen that the key factors that determine the cost of composite current collectors are the localization of equipment and the yield of mass production.

If the composite current collector is used on a large scale in the future, what fields will it be used first? Zhu Zhixiang said: "The first to be applied in the power (battery), high-end models will be the first to be introduced, and the current batteries of ZEEKR 001 and 009 are batteries that use composite aluminum foil. Energy storage is subject to cost issues, and even if it is safer, it is difficult for owners to consider using it. ”