Lithium Battery Packaging Film, Lithium Battery Separator And Battery Cell Blue Film

Lithium battery packaging film:

(1) Structure and characteristics of lithium battery packaging filmLithium battery packaging film is usually composed of three layers of aluminum foil (nylon layer) ON/Al/CPP or four layers (nylon layer) ON/Al/PA/CPP, among which, the outer nylon layer mainly plays a protective role to prevent the aluminum foil layer from being scratched, and the outer material is required to be puncture-resistant and impact-resistant. The aluminum foil layer in the middle acts as the base material, which acts as a waterproof and barrier, prevents moisture from entering and blocks oxygen to protect the battery contents. The main function of the inner heat seal layer (CPP) is heat sealing. According to the multi-layer structure, it has the functions of corrosion resistance, puncture resistance, aging resistance, insulation, moisture resistance, etc., and is an ideal packaging material for electronic products. The industry also calls it "aluminum-plastic film". In addition to the above properties, the recyclable characteristics of aluminum-plastic film are compounded with the concept of green environmental protection and adapt to the trend of the times.

(2) The application and future development of lithium battery packaging film can effectively protect the internal structure of lithium battery and ensure its safety and stability. In addition to being used in lithium battery packaging, it is widely used in the field of pharmaceutical packaging due to its excellent barrier properties and mechanical properties, which can effectively prevent drug deterioration and bacterial breeding. In addition, aluminum-plastic film has good transparency and barrier properties, which can maintain the freshness and taste of food, so it has a wide range of application prospects in the field of food packaging. Aluminum-plastic composite film can also be used in electronic components, optical instruments and other fields. The characteristics of aluminum-plastic film are excellent, and with the continuous progress of science and technology and the improvement of people's awareness of environmental protection, the market demand for aluminum-plastic film will be further expanded. In the future, with the continuous innovation of technology and the reduction of costs, the application field of aluminum plastic film will be broader. China's aluminum-plastic film manufacturers mainly include Selen Technology, Shanghai Zijiang Group, Zhejiang Daoming Optoelectronics, Mingguan New Materials, Hangzhou Foster, etc., matching different types of soft-pack lithium batteries, and each manufacturer has its own strengths. On the whole, the market size of China's aluminum-plastic film industry is on the rise. It is expected to grow rapidly in the future driven by the demand for downstream lithium batteries. According to the data, from 2021 to 2025, the scale of China's aluminum-plastic film market will grow at an average annual compound growth rate of 16.09%, and its market size is expected to further reach 13.32 billion yuan in 2025. With the popularity of new energy vehicles, smart phones and other electronic products and the growing market demand, the market scale of pouch lithium battery, as the core component, continues to expand. As one of the key materials of pouch lithium batteries, the market demand for aluminum-plastic film has also grown. It is expected to grow at a compound annual growth rate (CAGR) of 15.6% over the next few years.

Lithium battery separator:

(1) Characteristics and functions As one of the key inner components of lithium batteries, lithium battery separators play a vital role in batteries. It separates the positive and negative poles of the battery to prevent short circuits due to contact between the two poles, and also has the function of allowing electrolyte ions to pass through. The performance of the separator directly determines the capacity, cycling and safety performance of the battery. At present, there are the following types of lithium battery separators on the market:1. Polyolefin separators: including PP/PE/PP multi-layer composite microporous membranes, PP or PE single-layer microporous membranes, etc. This kind of separator is resistant to high and low temperatures, low density, stable chemical structure, excellent mechanical strength and good electrochemical stability. It is widely used in all kinds of lithium batteries. 2. Coated polyester film: polyethylene terephthalate is used as raw material, extrusion method is used to make thick sheets, and then made by bidirectional stretching. The price is higher, the thickness is generally 0.012mm, and it is widely used in FRP, building materials, printing, medicine and health and other industries. 3. Cellulose membrane: high strength, fast filtration speed, can capture coarse particles, can also collect gelatinous sediments, low resistance, low impurity content. 4. Polyimide film: It has excellent heat resistance and oxidation stability, but due to the harsh synthesis and film making conditions and high cost, it hinders the further application in membrane separation technology. 5. Polyamide membrane: From the perspective of hydrophilic and hydrophobic theory, polyphthalamide should be a better reverse osmosis membrane material. 6. Spandex or aramid film: high temperature resistance, low temperature output, long charging cycle life, moderate mechanical strength. In addition, according to the structure and composition, lithium battery separators can also be divided into porous polymer membranes, non-woven separators and inorganic composite membranes. Porous polymer membranes are separators with uniform pore distribution prepared by a variety of methods; Non-woven diaphragms are constructed of directional or random fibers, usually compounded with organic matter or ceramic gel; The inorganic composite film is obtained by combining inorganic nanoparticles with high polymers. Different kinds of diaphragms have different characteristics and scope of application. For example, polyolefin separators have advantages in terms of cost, stability, etc., and are suitable for most consumer electronics batteries; New separators, such as polyimide films, spandex or aramid films, have potential application value in the field of high-temperature and high-performance batteries.

(2) Development status and challenges Lithium battery separator materials at home and abroad are developing rapidly, showing a trend of diversification. In China, with the rapid development of the new energy vehicle market, the demand for lithium battery separators is growing. Leading enterprises such as Agile have global competitiveness in terms of production capacity, product quality, cost efficiency, and technology research and development. In recent years, the company has developed rapidly, and its production capacity and revenue have increased significantly, ranking first in the world in terms of diaphragm production capacity and shipments. At the same time, the lightening and thinning of the diaphragm has become an important trend in the development of the industry. The thinner the separator, the better it is to reduce the internal resistance of the battery and improve the energy density and endurance of the battery. For example, the mainstream dry separator in the power industry is 12 - 14 μm three-layer co-extruded separator, and the wet base film is 5 - 9 μm thick for conventional products, and some companies have been able to produce 4 μm thick lithium battery separator. However, the ultra-thinning of the diaphragm also brings with it a number of technical challenges. First of all, in the process of thinning the diaphragm, how to ensure its puncture resistance, mechanical strength and isolation characteristics to ensure product safety is a major technical challenge. Secondly, whether it is a dry or wet process, the preparation of ultra-thin separators puts forward higher requirements for process accuracy and stability. In addition, the production of ultra-thin separators requires advanced production equipment to ensure accuracy and stability, and domestic enterprises still need continuous efforts in equipment research and development and manufacturing. In the recent 13th Cell and Thin Film Industry Chain Development Summit Forum held in 2024, separator technology and market trend outlook became one of the core topics of heated discussion among participants. The senior executives and technical personnel of relevant enterprises also shared a lot of innovative design thinking and future development trends in this meeting. Despite facing many challenges, the development prospects of the lithium battery separator industry are still broad. With the continuous progress and innovation of technology, it is expected that more breakthroughs will be made in separator materials, processes and equipment in the future to further solve the technical challenges brought about by ultra-thinning. At the same time, driven by the continuous demand for lighter and thinner electronic products and the improvement of the performance of lithium batteries, the market demand for ultra-thin battery separators will continue to grow.

Cell Blue Film:

(1) Performance and advantages As a protective film on the surface of the square aluminum shell of the power battery, the mainstream material is PET film. It has many properties and advantages and plays an important role in power batteries. First of all, it has excellent wear resistance, which can effectively resist the friction that may be subjected to during transportation and use, and protect the surface of the cell. At the same time, it has excellent puncture resistance and reduces the risk of short circuits caused by sharp external objects. Its excellent mechanical strength allows it to withstand certain external force impacts and ensure the structural integrity of the cell. In the environment of long-term damp heat and temperature changes, the blue film of the battery cell can still remain stable and adapt to various complex working conditions. It also meets the 15-year service life requirement, providing a reliable guarantee for the long-term use of the battery. In addition, the characteristics of puncture resistance, corrosion resistance, and high pressure resistance make it safe to operate in different chemical environments and high voltage conditions. The characteristics of peeling off without residual glue facilitate the maintenance and replacement of batteries. Finally, the excellent explosion-proof and flame-retardant effect can effectively reduce safety risks in unexpected situations.

(2) Applications and challenges Cell blue film has a wide range of applications in lithium batteries. On the one hand, it plays an insulating role in the single battery, preventing a single cell from having a negative impact on other cell components due to various faults. It can prevent surface scratches and leakage during subsequent transportation and assembly of the battery, and can also play the role of waterproof and dustproof to better protect the battery. In the envelope detection machine, the blue film of the battery cell also has an important development trend. With the large-scale expansion of power battery production capacity, battery companies have higher and higher requirements for product safety, performance and quality control. As an insulating material, the quality inspection of blue film is crucial. Because the blue film is a highly reflective material, the thickness is only between 0.015mm and 0.20mm, there are many types of defects, and some defect samples are difficult to collect, and the overkill rate and missed detection rate of traditional algorithms are extremely high. In response to this problem, enterprises have launched standardized solutions, such as Huahan Weiye's comprehensive use of 2D + 2.5D + 3D + AI to achieve image-level feature fusion, meet the online accurate detection of subtle and low-contrast defects, and effectively improve battery quality control and yield. In addition, with the improvement of the endurance and charging speed of new energy vehicles, power batteries are gradually developing in the direction of lightweight, high efficiency and high voltage, and the market has put forward higher requirements for the insulation capacity and voltage resistance level of battery materials. Traditional blue film insulation solutions may be at risk of being replaced by UV-coated insulation, powder coatings, etc. However, at present, blue film is cost-effective and is still one of the main application schemes for electrical insulation of power batteries. In 2023, the cumulative sales volume of power batteries in China will be 616.3GWh, a year-on-year increase of 32.4%; The cumulative export of power batteries was 127.4GWh, a year-on-year increase of 87.1%. The expansion of the scale of the power battery industry provides a broad demand space for the blue film industry. All three are indispensable components of lithium batteries, and together they ensure the performance and safety of lithium batteries. The lithium battery packaging film and the battery cell blue film protect the battery cell from the outside and surface, and the lithium battery separator ensures the isolation of the positive and negative electrodes and the normal transmission of ions inside. Together, they play an important role in the development and application of lithium batteries.