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IPO on the Way, Defu Technology Empowers Tracks of 5G and New Energy

We are an enterprise engaged in the R&D, production and sales of high-performance electrolytic copper foil for 38 years. With the rapid development of the new energy vehicle market, the market demand for lithium battery copper foil has increased significantly, and product technology has also been rapidly iterated and upgraded. As one of the main suppliers of copper foil for lithium batteries in the world, Defu had completed the IPO process in 2022 and plans to be listed on the GEM of the Shenzhen Stock Exchange.

Constantly Strengthening Independent R&D and Enhancing Technical System

Our company has grown from an annual production capacity of 13,000 tons at the beginning of 2019 to an electrolytic copper foil enterprise with an annual production capacity of more than 100,000 tons. Thanks to the wise judgment of the market trend in 2019, we expanded against the trend and increased and seized the market when peer companies have limited production. But technological investment and technological progress are also the main driving forces supporting the development of enterprises.

The core manufacturing technology of electrolytic copper foil is the development of equipment and processes around electrochemistry and material science. For a long time, we have insisted on independent R&D and technology investment, focusing on the development of core materials in the upstream and downstream of electrolytic copper foil, and accelerating the localization process of core materials in the lithium battery and electronic circuit industries.

Over the years, our scientific research team has been cooperating with top domestic scientific research institutions such as the team of Professor Pei Jian of Peking University, the Department of Materials Physics of Xiamen University, and the Institute of Chemistry of the Chinese Academy of Sciences. A lot of in-depth research has been jointly carried out in the fields of development of additives and silane for electrolytic copper foil, analysis of crystal structure of copper foil, polyimide modification in flexible copper clad laminates and research and development of photoelectric polymer materials with alkyl branched chains.

At present, it has established an R&D technology system with the core of "basic theory and microscopic research of copper foil", "performance improvement of high-performance copper foil", "testing and control optimization of key process parameters", "design and optimization of production line equipment", and "testing and control optimization of water treatment". Up to now, the group company has a total of more than 100 authorized patents, has achieved industry leadership in the field of ultra-thin, high-tensile and high-modulus lithium battery copper foil, and has achieved core technological breakthroughs in the field of high-end electronic circuit copper foil.

A large number of new technologies that having made breakthroughs have been applied one after another, bringing a wave of new opportunities to the electrolytic copper foil industry. Defu Technology said that as a representative enterprise of the growth rate of the domestic copper foil industry in recent years, the company will continue to uphold the craftsmanship of a great country, lead the improvement and progress of copper foil materials, and set a benchmark for the copper foil industry.

Developing Special Additives to Improve the Performance of Lithium Battery Copper Foil

The quality of lithium battery copper foil products is inseparable from the core additives. Our scientific research team regards the introduction of additives as an important way of performance regulation in the electrolytic copper foil preparation process. By introducing additives into the electrolyte, the reaction potential of copper deposition can be changed to affect the microstructure and morphology of copper foil, thus be conducive to improving properties of electrolytic copper foil.

In order to solve the abnormalities such as edge tearing and strip breakage of the ultra-thin copper foil during the pole piece manufacturing process, our scientific research team independently synthesized an auxiliary brightener DG under the guidance of the team of Professor Pei Jian from the School of Chemistry, Peking University. If used in ultra-thin products, the ultra-thin copper foil will feature high tensile strength and high elongation.

At present, the auxiliary brightener DG has been widely used in the additive formula of various high-grade copper foils of our company. Taking 6-micron lithium battery copper foil as an example, the tensile strength can reach 400-600MPa, the elongation can reach more than 5%, and it can be customized according to customer needs. At the same time, we have cooperated with Xiamen University to conduct an in-depth analysis of the copper foil crystal structure and establish a clear additive-copper foil physical property relationship, ensuring the reliability of large-scale mass production of high-performance copper foil products.

Throwing agent is an additive that plays a key role in the process of electrolytic copper foil. Based on years of research experience in organic polymer materials, Professor Pei Jian's team innovatively suggested the use of modified polyether polymer compounds as dislocation agents. This type of throwing agent can form a "sticky layer" on the cathode, improve the polarization of the cathode, inhibit the deposition rate of copper ions, and make the copper foil crystallized densely. According to the CVS test, polyether polymer compounds are better at inhibiting the deposition rate of copper ions than small molecule compounds, which reflects that polyether polymer compounds can more effectively improve the overpotential of copper ion deposition.

The content of additives in the electrolyte-based copper foil production system is at the ppm level, and how to detect them has always been a pain point in the industry. Our scientific research team has independently developed the cyclic voltammetry stripping technology (CVS), which solved the problem of quantitatively tracking the effective concentration of additives in the electrolyte system. This technology can accurately measure the effective concentration of various additives in the electrolyte by comparing the influence of various additives in the electrolyte on the copper plating speed under the standard concentration and that under the actual additive concentration, so as to guide stable production.

Innovative Process Development to Expand Downstream Applications

Copper foil is used as a current collector in lithium batteries and is responsible for loading active materials and conducting current. In order to further increase the density of current collectors loaded active materials, our scientific research team and Song Yanlin's research group at the Institute of Chemistry, Chinese Academy of Sciences have successfully developed a three-dimensional porous copper foil current collector. This product has three-dimensional hole characteristics and increases the active material loading by about 50% while reducing the weight of the current collector by 30%, and it has great advantages in the application of pre-lithiation and all-solid-state batteries.

  High-frequency and high-speed printed circuit boards (PCBs) for 5G communications are widely used in servers, storage, base stations, automotive electronics, automotive radar, radio frequency devices, and aerospace military industries. They are the core components of modern electronic network transmission. Electrolytic copper foil as a conductor is the key basic material of PCB.

 According to the principle of skin effect, the electrolytic copper foil that affects conductor loss should have a very low profile to ensure low loss in high-frequency and high-speed application scenarios. How to produce sufficient bonding force between electrolytic copper foil and high-frequency and high-speed resin substrates under ultra-low profile conditions is a major pain point in the development of the domestic industry.

  Our scientific research team has developed a polymeric multifunctional silane coupling agent for ultra-low profile copper foil for 5G communication. During the research and development process, we fully learned from the successful experience of Professor Pei Jian's team in structural modification of functional polymer materials and used innovative chemical reactions to achieve different polymer properties.

  Through the technology development and application of polymeric silane coupling agent, the performance of the ultra-low profile HVLP copper foil developed by our scientific research team has reached the level of the products of Japanese benchmark enterprises.

  Jiujiang Design Optoelectronic Material Co., Ltd. ("Design Optoelectronic" for short) is a wholly-owned subsidiary of our company. Since its establishment in 2013, Design Optoelectronics has started the industry-university-research cooperation with the team of Professor Pei Jian on optoelectronic polymer materials with alkyl branched chains, and invested in the establishment of a complete set of manufacturing and inspection technical standards for this series of products. These products entered the market under the trade name of BRAC in 2014, and were released to relevant users of optoelectronic functional polymer materials. A series of products had been launched under the trade names of IBRAC, DPP, BDOPV, etc. from 2015 to 2022. According to reports, the chemical molecular structure of this series of products contains branched substituted alkyl groups with different numbers of branch nodes, which not only significantly improves the solubility of organic polymers in organic solvents, but is also able to significantly improve or regulate the ultimate carrier mobility of photoelectric functional polymer devices.

  After nearly 10 years of development, Design Optoelectronics has developed more than 100 kinds of branched alkanes products, served more than 300 customers around the world, and created an accumulated economic value of over 50 million yuan. With the continuous optimization and improvement of the photoelectric polymer mobility brought about by this technology, its application in thin film transistors, photoelectric sensors and other fields will continue to expand and leap forward, said President Luo Jia.

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