Lithium ion battery electrode slice, electric core and its making method

Abstract

This invention discloses pole plates of Li ionic cells, in which, a micro-porous film is set on the pole plate with PVDF as the matrix and chemical gel formed by chimical cross-link is set in the micro-porous film.This invention also discloses a Li-ionic cell core with said pole plates and a preparation method including: the PVDF film forming chemical gel inside by irradiation and cross-link has the heat contraction rate of nearly zero under 100-220deg.C, which can prevent electronic short circuit of positive and negative pole plates caused by over contraction of intensified switchable Polyolefin micro-hole septums under high temperature when being coated on the pole plates.

Description

technical field

[0001] The invention relates to the field of lithium-ion batteries, in particular to a high-safety lithium-ion battery pole piece, a battery cell and a preparation method for the battery cell. Background technique

[0002] Lithium-ion secondary batteries have the advantages of high working voltage, high energy density, and environmental protection, and are widely used in mobile phones, notebook computers, power tools, electric bicycles and other products.

[0003] Polymer lithium-ion secondary batteries usually use porous polyvinylidene fluoride copolymer PVDF-HFP as a physical gel separator. The typical process is the classic Bellcore process. See US Patent 5,540,741. This method uses dibutyl phthalate DBP As a plasticizer, the DBP is removed by methanol multi-stage extraction method to form pores. The physically cross-linked PVDF-HFP has good liquid absorption and liquid retention. It is used as a gel electrolyte after absorbing liquid and swelling. The pro...

Examples

Embodiment 1

[0066] Manufacture of Positive Electrode

[0067] The positive electrode active material adopts spinel lithium manganese oxide LiMn 2 o 4 , Adhesive using KYNAR 761PVDF, acetylene black as conductive agent, mixed and dissolved in N-methylpyrrolidone (NMP) solvent at a ratio of 95:3:5, after mixing and defoaming, evenly coat on both sides of the aluminum foil collector, After drying and calendering, the two sides are respectively coated with porous polyvinylidene fluoride film layer and subjected to radiation cross-linking treatment.

[0068] Coated porous polyvinylidene fluoride membrane layers include:

[0069] A. For ingredients, dissolve 2.5 parts of KYNAR 761PVDF and 1.25 parts of KYNAR 2801PVDF-HFP in 96.25 parts of N-methylpyrrolidone (NMP) solvent, add 7.5 parts of DBP, continue to mix evenly, and perform defoaming treatment;

[0070] B. Coat the above-mentioned slurry (glue) on both sides of the positive electrode sheet after rolling, and control the single-sided th...

Embodiment 2

[0082] The rest is the same as in Example 1, and the negative pole piece is also coated with porous polyvinylidene fluoride film layer and irradiation crosslinking treatment process respectively, and the thickness of one side of the polyvinylidene fluoride film after drying is controlled: 10 microns.

[0083] Using the same method to carry out the battery safety test, the passing rate is 92%.

Embodiment 3

[0085] The rest are the same as in Example 2, only the thickness of one side of the porous polyvinylidene fluoride film coated on the positive and negative electrodes is adjusted to 4 microns.

[0086] The battery safety test was carried out with the same method, and the passing rate was 85%.

technical field

[0001] The invention relates to the field of lithium-ion batteries, in particular to a high-safety lithium-ion battery pole piece, a battery cell and a preparation method for the battery cell. Background technique

[0002] Lithium-ion secondary batteries have the advantages of high working voltage, high energy density, and environmental protection, and are widely used in mobile phones, notebook computers, power tools, electric bicycles and other products.

[0003] Polymer lithium-ion secondary batteries usually use porous polyvinylidene fluoride copolymer PVDF-HFP as a physical gel separator. The typical process is the classic Bellcore process. See US Patent 5,540,741. This method uses dibutyl phthalate DBP As a plasticizer, the DBP is removed by methanol multi-stage extraction method to form pores. The physically cross-linked PVDF-HFP has good liquid absorption and liquid retention. It is used as a gel electrolyte after absorbing liquid and swelling. The pro...

Examples

Embodiment 1

[0066] Manufacture of Positive Electrode

[0067] The positive electrode active material adopts spinel lithium manganese oxide LiMn 2 o 4 , Adhesive using KYNAR 761PVDF, acetylene black as conductive agent, mixed and dissolved in N-methylpyrrolidone (NMP) solvent at a ratio of 95:3:5, after mixing and defoaming, evenly coat on both sides of the aluminum foil collector, After drying and calendering, the two sides are respectively coated with porous polyvinylidene fluoride film layer and subjected to radiation cross-linking treatment.

[0068] Coated porous polyvinylidene fluoride membrane layers include:

[0069] A. For ingredients, dissolve 2.5 parts of KYNAR 761PVDF and 1.25 parts of KYNAR 2801PVDF-HFP in 96.25 parts of N-methylpyrrolidone (NMP) solvent, add 7.5 parts of DBP, continue to mix evenly, and perform defoaming treatment;

[0070] B. Coat the above-mentioned slurry (glue) on both sides of the positive electrode sheet after rolling, and control the single-sided th...

Embodiment 2

[0082] The rest is the same as in Example 1, and the negative pole piece is also coated with porous polyvinylidene fluoride film layer and irradiation crosslinking treatment process respectively, and the thickness of one side of the polyvinylidene fluoride film after drying is controlled: 10 microns.

[0083] Using the same method to carry out the battery safety test, the passing rate is 92%.

Embodiment 3

[0085] The rest are the same as in Example 2, only the thickness of one side of the porous polyvinylidene fluoride film coated on the positive and negative electrodes is adjusted to 4 microns.

[0086] The battery safety test was carried out with the same method, and the passing rate was 85%.