Preparation method of lithium battery diaphragm material

Abstract

The invention discloses a preparation method of a lithium battery diaphragm material and belongs to the field of synthesis of battery materials. The preparation method disclosed by the invention comprises the following steps: firstly mildewing on the surfaces of cotton linters by utilizing rich microorganisms in a liquid supernatant in a biogas tank to initially activate and defibrillate cotton fibers, and sterilizing and de-coloring by using hydrogen peroxide; then adding sodium dodecyl benzene sulfonate serving as a surface active agent into a sodium hydroxide solution to promote the defibrillation of the cotton linter fibers in the cooking process, removing impurities in raw materials to purify celluloses, and preliminarily hydrolyzing through the celluloses and pulping to keep close and uniform among the fibers; finally, polymerizing a layer of dopamine on the surfaces of the fibers to form a dense porous structure among the fibers and improve the mechanical strength of a diaphragm, reducing the looseness among the fibers through ultra-fine grinding and obtaining the lithium battery diaphragm material through sheet making and hot pressing. The lithium battery diaphragm material obtained by the preparation method disclosed by the invention is good in mechanical strength, a large amount of organic solvents are not needed in the preparation process, the obtained material is durable, the service life of the lithium battery diaphragm material is prolonged by 2 times or above compared with that of a conventional diaphragm, and the safety is greatly improved.

Description

technical field [0001] The invention discloses a preparation method of a lithium battery diaphragm material, belonging to the field of battery material synthesis. Background technique [0002] Due to environmental pollution and energy shortages, in recent years, the national development plan has increased research efforts and financial support for lithium-ion batteries. As one of the key components of lithium-ion battery products, the separator is highly regarded by the country in the new material industry for its production and use. Pay attention to. Lithium batteries are mainly composed of diaphragm, positive electrode material, negative electrode material, and electrolyte. The diaphragm is a porous insulating layer with a thickness of 8-40 μm. The passage of electrons allows lithium ions in the electrolyte to pass freely, thereby realizing the important role of ion conduction. [0003] At present, the commercialized lithium-ion battery separators mainly include dry-proc...

AI Technical Summary

Problems solved by technology

[0007] The technical problem mainly solved by the present invention: for traditional lithium battery separator materials appearing in the process of preparation and use, various performance indicators cannot be taken into account as a whole. To improve the specific energy and high-power charge and discharge capacity of lithium ion batteries, it is necessary to improve the performance of the separator. porosity and reduce the thickness of the membrane, but these changes will reduce the strength and impact resistance of the membrane, further reducing the safety of the lithium battery. A preparation method for the lithium battery membrane material is provided. The invention uses a cheap and easy-to-obtain Cotton linters are used as raw materials. Firstly, the rich microorganisms in the supernatant of the biogas tank are used to mold the surface of the cotton fibers, so that the cotton fibers can be initially activated and defibrillated, and then sterilized and decolorized with hydrogen peroxide. Then, surfactant twelve is added to the sodium hydroxide solution. Sodium alkylbenzene sulfonate, during the cooking process, promotes the fiberization of cotton linters, removes impurities in the raw materials, and purifies the cellulose. After preliminary hydrolysis by cellulase, it is beaten to make the fibers compact and even. A layer of dopamine is polymerized on the surface of the fiber to form a dense porous structure between the fibers and improve the mechanical strength of the separator. After ultra-fine grinding, the porosity between the fibers is reduced, and then the lithium battery separator material is obtained by sheet hot pressing.