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Code:002389   Name:NanYang Tech

2015 or will become the first year of rapid development of the battery separator industry

Source:中国纺织报 Date:Mar 20,2015


At the beginning of 2015, the national and local governments have continuously issued a large number of policies to speed up the development of new energy vehicles, not only to improve the auto market activity, but also to the energy car "engine" - lithium battery concern, many lithium battery industry investment Began to gear up, ready to put the market to seize the big forces.

In the lithium battery structure, the battery separator is one of the key inner components, but also the highest technical barriers to a high value-added materials, accounting for about 20% of the cost of lithium batteries to 30%. The diaphragm determines the quality of the battery interface structure, internal resistance, etc., a direct impact on battery capacity, cycle and safety performance characteristics, excellent performance of the diaphragm to improve the overall performance of the battery has an important role. More than the industry said that in 2015, or will become the battery separator industry, the rapid development of the "first year."

  "Two jump" stage of enterprise rapid progress


From the battery separator industry trends, mainly showing two kinds of situation, one is inclined to more thin consumer lithium battery separator, mainly for mobile phones, notebook computers and Internet applications such as distributed application architecture, to enhance the lithium battery Capacity and portability; the other is inclined to use thick film or multi-layer composite diaphragm of the battery pack, mainly for electric vehicles, large-scale energy storage power plants and other large power applications require better energy output and power characteristics, The safety requirements, can take into account the lithium battery capacity and safety performance.

Zhang Yu Bing, head of the China Film Industry Association, pointed out that China's battery separator industry is not only facing the two major markets, but also in the "two jump" type across the development process, film processing and production equipment manufacturing capacity leading enterprises have been in the first wave Win.

2012 to 2014, is the production process across the lead to promote the industrial upgrading of the "first jump", the stage for the production process and equipment manufacturing capacity to achieve a breakthrough period, the innovation driving force will be their own industrial technology research and development occupy leading position. In the film process has accumulated experience, and in the production of equipment manufacturing innovation capacity of enterprises in the current round of the tide of domestic tide stand out. According to the film industry association released in 2014 data analysis shows that there are already Foshan Donghang Optoelectronics Group, Xinxiang Grenada Group and other 18 companies to complete the history of jump.

2015 ~ 2020 for the basic research capacity of materials to guide the upgrading of the diaphragm industry to lead the "second jump." From the whole industry ecology, after the completion of the first phase of the production process upgrade, the industry concentration will gradually increase, leading enterprises will continue to extend, through the construction of polymer materials laboratory and other forms to enhance the matrix material research and development capabilities, so as to promote the industry with The ability to modify and functionalize the base material, and ultimately occupy the market with product functional differences.

  Diaphragm localization is the development of the primary task


Diaphragm is the highest threshold of lithium industry chain technology. In China, lithium-ion battery raw materials have been basically achieved localization, but the diaphragm material is mainly dependent on imports, making the key technology of the diaphragm by Japan and Europe and the United States monopoly. Diaphragm in China, although there are production, but the indicators also reach the level of foreign, and some even reach the requirements of the use.

Liaoning Chaoyang Liyuan New Energy Co., Ltd. Deputy General Manager Li said that the battery is mainly reflected in the diaphragm diameter contraction heating point control aspects. Good diaphragm material is generally about 160 degrees Celsius aperture will appear to shrink phenomenon, and domestic diaphragm is generally 130 degrees Celsius will shrink, which caused the battery in the use of domestic diaphragm easy to heat, easily lead to high temperatures , And even cause an explosion. "At present, the quality of domestic diaphragm products can only be with the international brand in 2004 the level of quality level." Li said.

BYD New Energy Co., Ltd. technical experts Ge Tianli said that high-end products, especially the power battery on the consistency of the membrane requirements are extremely high. In addition to the basic requirements of thickness, surface density, and mechanical properties, there is a high demand for the uniformity of the size and distribution of the membrane micropores. At present, there are still too thick thickness of the domestic diaphragm, uneven corners, the surface of the crystal point too much and so on, seriously affecting the battery capacity, endurance and mass production. At present, BYD in E6, F3DM and other products are imported Celgard and other diaphragm products, and in the traditional low-power grid energy storage battery is preferred to use domestic brands.

Tianjin Power Research Institute Professor Wang Jiqiang senior engineer pointed out that although the domestic lithium battery diaphragm capacity growth is rapid, but the high-end diaphragm technology to be a breakthrough, the diaphragm material is still China's lithium battery industry short board, using innovative technology to promote high-end diaphragm localization is the primary task. "From the development of lithium battery point of view, we are still foundry industry stage, not their own core technology.From the core technology to equipment manufacturing and then to the lack of skilled workers, we want to an industry chain in the overall transcendence, To make up for the shortcomings of research and development. "Wang Jiqiang said.

  Three aspects to enhance product market adaptability


After several years of development, China's lithium battery separator has made great progress, but the requirements of the market in the ever-changing, Tianjin University of Technology Professor Guo Bingchen pointed out that in order to better adapt to the Chinese lithium market requirements of the diaphragm, but also for our diaphragm The healthy development of the enterprise itself, the future development of the battery separator should pay attention to the following three aspects.

The first is to improve the level of independent innovation, to ensure the stability of product quality and consistency. Diaphragm enterprises in the next few years should focus on research and development rather than industrialization. Diaphragm future research and development focus is the new energy vehicle power battery separator. In the power battery, in order to obtain high energy, to provide high power, a battery usually need to use dozens or even hundreds of batteries in series. For example, because the lithium battery has a potential explosion hazard, the safety of the diaphragm is essential, so the need to focus on the heat resistance of the diaphragm, the production can charge and discharge process, large area positive and negative short circuit can still keep the diaphragm Integrity of the high temperature composite diaphragm.

Second, we should pay attention to the development of raw materials for the diaphragm. China's diaphragm products and the gap between foreign countries, largely depends on the quality of raw materials is not up to standard. Foreign well-known diaphragm manufacturers are many of their own production of raw materials, or with the raw materials manufacturers to develop and produce special materials, and the domestic market is "fragmented" state, the production and use of fault problems after another. But it is worth mentioning that the current Nantong Tianfeng Group has been jointly with Nanjing University and Sinopec cooperation in the development of lithium battery separator special materials.

Finally, to build a unique diaphragm production line. Diaphragm production line process is very strong, to develop their own process line, it is necessary to build a number of high efficiency, suitable for their own characteristics of the production line. Independent research and development design, in the global selection of the most suitable equipment, coupled with the domestic mature film manufacturing equipment, design companies to provide equipment, can meet the needs of diaphragm production.

case analysis

Battery separator industry in the domestic development time is not short, but it has been "tepid", technical barriers have always been difficult to break. At present, the diaphragm production in accordance with the process can be divided into dry and wet two categories, this issue, we take the wet process, for example, to explore the difficulty of the domestic battery diaphragm in the end where the production.

The lack of research and development of matrix raw materials troubles the development of the industry

China's wet diaphragm industry development path of the most difficult problem is the lack of basic raw material research and development capabilities. The use of matrix materials used in the diaphragm mechanical properties of the diaphragm and the degree of infiltration with the electrolyte and other important indicators have a direct relationship.

Wet process The production of the base material of the diaphragm product includes the preparation and modification of polypropylene, polyethylene materials and additives. International major diaphragm suppliers Asahi Kasei and East Gas Chemical and the United States Celgard Group and other giants have their own polymer laboratories, can independently produce part of the polypropylene, polyethylene materials. In contrast, China's lithium battery companies are basically used by the base material through outsourcing, its own R & D strength is not strong.

In the matrix material, although China is mainly dependent on imports, but the supply is relatively sufficient, the amount is not the current stage of the development of wet diaphragm industry, the main factors, from the industry to develop the ability to continue to innovate, only with the matrix material research and development and production capacity, China's diaphragm enterprises to serve as the world leader in the diaphragm industry. To Japan, East Chemical, for example, with the United States and chemical chemical cooperation, the East Chemical Chemical using the United States and chemical research and development of high melting point polyethylene material, introduced a melting point of up to 170 ℃ ~ 180 ℃ wet PE lithium battery separator. The use of special treatment of the matrix material, greatly improving the performance of the diaphragm to meet the special purpose of lithium batteries, but also to East fuel chemical in the US market share increased by 38%.

In addition, the lack of precision control of the production process leading to poor product consistency index is also the main reason for the development of wet diaphragm industry. In view of the diaphragm products on the product uniformity of the stringent requirements to strengthen the production process precision control the same urgent.

Wet production process 6 big links more difficult

Feeding and batching systems. The stability of the feed and ingredients is directly related to the stability of the extrusion process and has an important effect on the thickness of the slab and film. For example, the ratio of the main material and the pore-forming agent is the size and distribution of the pore diameter of the battery separator One of the factors. Therefore, the feeding and ingredients must be relatively high precision guarantee, try to install the computer precision control of the online real-time measurement system.

Extrusion mixing system. This aspect is particularly important throughout the wet process and needs to meet the following requirements: (1) able to have a strong shear plasticizing capacity, so that the main material fast, uniform plastic; (2) can have a good Mixing effect, so that the main material and pore-forming agent evenly mixed; (3) to make the material and the extruder does not slip between, not back flow, to stabilize the feed. This link is critical to the uniformity of the mix and the stability of the feed.

Casting cooling system. The system needs to meet the following requirements: (1) cooling the melt to form a thick film; (2) quenching the melt, reducing the thickness of the thick film to prevent the formation of spherulites; reduce the thickness of the thick film to prevent the formation of spherulites; (3) quenching the "plastic-pore-forming agent" mixture melt, so that the pore-forming agent and the polyolefin thermotropic phase separation; (4) quenching the surface of the thick film, so that the phase separation has been the majority of pore-forming agent In the thick film inside, so that pore-forming agent is not easy to flow away and exudation. The link to the temperature control and cooling speed control requirements of high precision.

Stretching system. Tensile system is a core part of film production, the purpose is to make the molecular chain in the process of stretching the orientation, thereby improving and improving the application performance of the product. After the two-way stretching of the oil film, the molecular chain has been vertical and horizontal orientation of the two directions, and pore agent is also evenly distributed in the orientation of the molecular chain between the formation of a special "net - oil" mixed structure. From the thermodynamic point of view, the microporous or microporous shape of the membrane has been formed, but the pore-forming agent still occupies the position of the hole, blocking the hole of the diaphragm, making the micro-porous state is difficult to present.

Winding system. The requirements of the winding tension is always maintained within the appropriate range, and can be adjusted in real time, lithium-ion diaphragm oil film due to the presence of pore-forming agent, winding tension is too small prone to slip slip, and too much tension will cause longitudinal Too tight produce wrinkles, affecting the quality of follow-up processing.

Washing and drying system. This part is a unique process of wet lithium ion separator production process. The role of the system is to pore-forming agent from the pores of the oil film out or extracted out to form a lithium ion through the microporous structure. The washing process is required to quickly meet the requirements of high-speed production, requiring high extraction capacity to meet the requirements of lithium ion separator low pore-forming agent residues.

Environmental pollution problems need to be solved

Battery membrane wet process requires the addition of organic solvents, and then in the diaphragm with microporous membrane manufacturing process, the solvent extraction can be carried out before the one-way or two-way stretching, extraction after the stereotypes and film formation, can also be extracted To stretch. The ultra-high molecular weight polyethylene microporous film produced by this method has good mechanical properties.

Compared with the dry company, wet film preparation process is relatively easy to control, can better control the pore size, pore size distribution and porosity. But the preparation process requires a lot of solvent, likely to cause environmental pollution, how to reduce the process of environmental hazards, is the vast majority of wet business the most troublesome thing. From the international market point of view, Japanese and Korean manufacturers to adopt the wet process more companies, mainly Japan Asahi Kasei, East Chemical, Mitsubishi Chemical, South Korea SK Chemical.

Equipment investment costs are high

Wet process to produce battery separator products, the current equipment required for the majority of imports, there is no complete set of production lines are domestic equipment, of which 100% of the mixer imports. The total investment is estimated at 69.86 million yuan, of which the investment in fixed assets is 33.7 million yuan, the input of current assets is 15.4 million yuan, the raw material safety stock of 20 months is 20.76 million yuan, Which accounted for 48% of fixed assets investment, so many companies feel "pressure mountain".

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