Analysis of the development trend of lithium iron phosphate battery separator industry

by:CTECHi     2021-07-26

The separator is one of the important components of lithium-ion batteries, and is usually referred to as battery separator, separator paper, ion separation membrane, etc. The main function of separator in lithium battery materials is to isolate the positive and negative electrodes to prevent battery self-discharge and Problems such as short-circuit of the two poles. Because the safety, permeability, porosity and membrane thickness of the diaphragm will affect the ion conductivity and mechanical strength each other, different design methods must be applied to manufacture different products, such as single-layer, double-layer and three-layer. The isolation film. What is a lithium battery separator? In the structure of lithium batteries, the diaphragm is one of the key inner components. The performance of the diaphragm determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle and safety performance of the battery. A diaphragm with excellent performance plays an important role in improving the overall performance of the lithium battery. The main function of the separator is to separate the positive and negative electrodes of the battery to prevent short-circuiting due to contact between the two electrodes. In addition, it also has the function of allowing electrolyte ions to pass through. The material of the diaphragm is non-conductive, and its physical and chemical properties have a great influence on the performance of the battery. Different types of batteries have different separators. For the lithium battery series, since the electrolyte is an organic solvent system, a separator material resistant to organic solvents is required. Generally, a high-strength thin-film polyolefin porous film is used. Requirements for lithium battery separator 1. It has electronic insulation to ensure the mechanical separation of the positive and negative electrodes. 2. It has a certain pore size and porosity to ensure low resistance and high ionic conductivity, and has good permeability to lithium ions. 3. Since the solvent of the electrolyte is a strongly polar organic compound, the diaphragm must be resistant to corrosion by the electrolyte and have sufficient chemical and electrochemical stability. Fourth, it has good wettability to electrolyte and has sufficient liquid absorption and moisture retention capacity. 5. It has sufficient mechanical properties, including puncture strength, tensile strength, etc., but the thickness is as small as possible. 6. Good spatial stability and smoothness. 7. Good thermal stability and automatic shutdown protection performance. Power lithium batteries have higher requirements for separators, and composite membranes are usually used. Preparation method of lithium battery diaphragm The preparation method of lithium battery diaphragm is divided into two types: dry method and wet method. The dry method is to melt, extrude, and blow a polyolefin resin into a crystalline polymer film. After crystallization and annealing, a highly oriented multilayer structure is obtained, which is further stretched at high temperature to peel off the crystal interface , Forming a porous structure, can increase the pore size of the film. The dry method has two methods: one-way stretching and two-way stretching. The wet method is also called phase separation method or thermally induced phase separation method. It mixes liquid hydrocarbons or some small molecular substances with polyolefin resin, heats and melts to form a uniform mixture, then cools down for phase separation, presses the membrane, and then The membrane is heated to a temperature close to the melting point, biaxially stretched to align the molecular chains, and finally kept for a certain period of time, and the residual solvent is eluted with volatile substances to prepare interpenetrating microporous membrane materials. The development trend of lithium iron phosphate battery separator industry ● The market prospect of lithium iron phosphate battery separator industry is broad, and the development potential is huge. At present, the low-end products of the industry have entered a competitive stage, corporate profits are becoming more and more equal, and industry integration and market segmentation are about to be completed . In the future, the overall product price of the lithium iron phosphate battery separator industry will further decline, and more product innovations will meet the different needs of downstream industries. ●With the advancement of technology and the development of society, safety issues will inevitably receive more and more attention from the society. In the process of charging and discharging, the high temperature resistant composite diaphragm that can maintain the integrity of the diaphragm after a large area of u200bu200bpositive and negative electrodes is short-circuited will surely be affected. Favor of the market. In order to improve the safety of lithium iron phosphate batteries, coating nanomaterials such as ceramics on polyolefin separators or adopting new matrix materials has become a future technology development trend. ●Develop ultra-thin diaphragm to increase unit energy density. With the development of the market, lighter, thinner and smaller 3C electronic products will continue to enter our lives. Such products require thinner lithium-ion battery separators to make batteries. At the same time, the pursuit of capacity for lithium batteries also requires thin films. However, the production and preparation of ultra-thin diaphragms requires high equipment and technology. Among lithium battery materials, diaphragm technology barriers and gross profit margins are relatively high, and it is also the last material to achieve localization. With the improvement of the technical level of domestic lithium battery diaphragm equipment, the gap in product quality with imported equipment will be further narrowed. The cost-effective advantage of domestic equipment and the substitution effect of imported equipment will become more and more obvious.

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