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Diaphragm well bonded with positive electrode and negative electrode and preparation method thereof

A positive and negative electrode and separator technology, applied in the field of separator and its preparation, can solve the problems of poor cycle stability, increased lithium ion transmission path, and poor adhesion, so as to inhibit the expansion and deformation of the battery cell and improve cycle stability performance, and the effect of improving safety performance

Active Publication Date: 2022-05-31
JIANGSU HORIZON NEW ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, because the styrene-butadiene rubber (SBR) binder is used in the negative electrode, it has almost no affinity with PVDF, so the PVDF rubber-coated separator has almost no adhesion to the negative electrode.
Poor adhesion to the negative electrode leads to: (1) large pores between the negative electrode sheet and the diaphragm, increased lithium ion transmission paths, increased internal resistance, and poor cycle stability; (2) Pores between the negative electrode sheet and the diaphragm Larger, the gas accumulation during the charging and discharging process, and the heat generated will cause the battery cell to expand and deform, thus causing safety problems; (3) The electrolyte is unevenly distributed between the positive electrode sheet and the diaphragm and between the negative electrode sheet and the diaphragm, resulting in Decrease in cycle performance; (4) The thickness of the cell increases, resulting in a decrease in the energy density of the battery

Method used

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  • Diaphragm well bonded with positive electrode and negative electrode and preparation method thereof
  • Diaphragm well bonded with positive electrode and negative electrode and preparation method thereof
  • Diaphragm well bonded with positive electrode and negative electrode and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] (1) pulping:

[0048] Take PVDF water-based slurry as slurry A;

[0049] Take 15 parts of ultrapure water, 2 parts of styrene-butadiene rubber, 1 part of hydroxymethylcellulose sodium glue, 0.3 parts of hydroxy acid amine salt dispersant, disperse and stir for 30 minutes; add 1.5 parts of peroxide crosslinking initiator diisoperoxide Propylbenzene, keep stirring for 30 minutes; add 0.2 parts of polyether wetting agent, and stir for 10 minutes to complete the preparation;

[0050] (2) Coating:

[0051] Take slurry A and slurry B, and apply them on the positive and negative surfaces of the separator respectively, and the density of the coating surface is 1g / m 2 ; Dry at 60°C to obtain a rubber-coated diaphragm; the diaphragm is an alumina-coated diaphragm;

Embodiment 2

[0053] (1) pulping:

[0054] Take PVDF water-based slurry as slurry A;

[0055] Take 10 parts of ultrapure water, 1 part of styrene-butadiene rubber, 1 part of hydroxymethylcellulose sodium glue, 0.2 parts of sorbitan monooleate dispersant, disperse and stir for 30 minutes; add 1 part of peroxide crosslinking initiator Di-tert-butylperoxycumene, keep stirring for 30 minutes; add 0.2 parts of silicone and polyether mixture wetting agent, and stir for 10 minutes to complete the preparation;

[0056] (2) Coating:

[0057] Take slurry A and slurry B, and apply them on the positive and negative surfaces of the separator respectively, and the density of the coating surface is 0.3g / m 2 ; Dry at 55°C to obtain a rubber-coated diaphragm; the diaphragm is a boehmite-coated diaphragm;

Embodiment 3

[0059] (1) pulping:

[0060] Take PVDF water-based slurry as slurry A;

[0061] Take 20 parts of ultrapure water, 4 parts of styrene-butadiene rubber, 2 parts of hydroxymethylcellulose sodium glue, 0.5 parts of hydroxy acid amine salt dispersant, disperse and stir for 30 minutes; add 3 parts of peroxide crosslinking initiator tert-butyl peroxide Propylbenzene, keep stirring for 30 minutes; add 0.4 parts of alcohol alkoxylate wetting agent, and stir for 10 minutes to complete the preparation;

[0062] (2) Coating:

[0063] Take slurry A and slurry B, and apply them on the positive and negative surfaces of the separator respectively, and the density of the coating surface is 1.5g / m 2 ; Dry at 55°C to obtain a rubber-coated diaphragm; the diaphragm is a silica-coated diaphragm;

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Abstract

The invention discloses a diaphragm well bonded with a positive electrode and a negative electrode and a preparation method thereof, the surface, close to the positive electrode, of the diaphragm is coated with slurry A, and the slurry A is PVDF aqueous slurry; the surface, close to the negative electrode, of the diaphragm is coated with slurry B, and the slurry B comprises ultrapure water, styrene butadiene rubber, a carboxymethyl cellulose sodium glue solution, a dispersing agent, a peroxide crosslinking initiator and a wetting agent. According to the preparation method, peroxide is added into the slurry B, crosslinking between the negative plate and SBR on the diaphragm is initiated under the co-heating condition, and the cohesiveness between the negative plate and the diaphragm is enhanced; due to high cohesiveness between the pole piece and the diaphragm, battery cell expansion deformation caused by heat and gas production can be inhibited in the charging and discharging process of the battery, so that the safety performance of the battery is improved; the pore between the negative plate and the diaphragm is reduced, the lithium ion transmission path is shortened, the internal resistance is reduced, and the cycling stability of the prepared battery is improved; and the thickness of the battery cell is reduced, and the energy density of the prepared battery is improved.

Description

technical field [0001] The invention relates to the technical field of battery separators, in particular to a separator well bonded to positive and negative electrodes and a preparation method thereof. Background technique [0002] Lithium-ion batteries are composed of four main functional parts, positive and negative electrolytes and separators. Among them, the main function of the separator is to provide a physical barrier between the electrodes to prevent short circuits, and it also provides a transmission channel for lithium ions. However, there is no glue on the surface of the commercial ceramic-coated separator, so that there is no bond between the pole piece and the separator, and there are still pores, which leads to an increase in the lithium ion transmission path, an increase in internal resistance, and a poor cycle stability; During the charging and discharging process of the battery, there will be heat and a small amount of gas generated, which will cause the ce...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/403H01M50/431H01M50/46H01M50/491
CPCH01M50/403H01M50/431H01M50/46H01M50/491Y02P70/50Y02E60/10
Inventor 张学虎张立斌赵海玉陈朝晖
Owner JIANGSU HORIZON NEW ENERGY TECH CO LTD