Method for preparing high-performance lithium-ion battery diaphragm through vacuum ultraviolet grating modification

Abstract

The invention discloses a method for preparing a high-performance lithium-ion battery diaphragm through vacuum ultraviolet grating modification. The method comprises the steps of: irradiating a polyolefin diaphragm by using a vacuum ultraviolet lamp under the protection of nitrogen; after the irradiation, immediately placing in a monomer under pure nitrogen protection and carrying out a grafting reaction; and volatilizing un-grafted monomers to obtain the high-performance lithium-ion battery diaphragm subjected to grafting modification. According to the method for preparing the high-performance lithium-ion battery diaphragm through vacuum ultraviolet grating modification, disclosed by the invention, the defects of low efficiency and complicated preparation process of an existing grating method are overcome, a polar material is rapidly grafted on the surface of the polyolefin diaphragm, and the affinity and the oxidization resistance of an electrolyte of the diaphragm are improved, thus the high-performance lithium-ion battery diaphragm with high magnification, high cycle service life and strong oxidization resistance capacity is obtained.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a method for preparing high-performance lithium-ion battery separators through vacuum ultraviolet grafting modification. Background technique [0002] At present, the separators widely used in lithium-ion batteries are mainly made of polyolefins (polyethylene, polypropylene, or a composite of the two). Polyolefin is a non-polar material, and the electrolyte usually uses polar substances such as dimethyl carbonate and ethylene carbonate as solvents. Therefore, the poor compatibility between the diaphragm and the electrolyte makes it difficult for the prepared membrane to be completely infiltrated by the electrolyte solution, resulting in poor liquid absorption. In addition, the polyethylene separator also has the disadvantage of poor oxidation resistance, and is easily oxidized in the battery to cause yellowing and blackening, and the battery capacity decreases. Th...

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Problems solved by technology

[0004] Chinese patent application CN101735470A discloses that the polypropylene film to be treated is irradiated with electron beams, and grafted for 2 hours at 50°C to prepare a polypropylene battery separator grafted with glycidyl methacrylate. Constant current charge and discharge tests in lithium-ion batteries show that it has good electrochemical performance, but the grafting reaction time is too long, making it difficult to mass-produce and industrialize

The method is complex and unfavorable for improving production efficiency

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