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High-safety composite diaphragm and preparation method thereof

A composite diaphragm and a safe technology, applied in the field of high-safety composite diaphragm and its preparation, can solve the problems such as the inability to effectively suppress the chain reaction of internal short circuit, and achieve the effects of avoiding battery thermal runaway, inhibiting heat accumulation, and improving safety.

Pending Publication Date: 2020-09-22
TIANJIN LISHEN BATTERY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for high energy density systems, the "blocking" strategy cannot effectively suppress the occurrence of internal short circuits and the chain reactions triggered by them.

Method used

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  • High-safety composite diaphragm and preparation method thereof
  • High-safety composite diaphragm and preparation method thereof
  • High-safety composite diaphragm and preparation method thereof

Examples

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preparation example Construction

[0087] In order to prepare the high-safety composite diaphragm provided by the present invention above, see figure 1 Shown, the present invention also provides a kind of preparation method of high safety composite diaphragm, comprises the following steps:

[0088] The first step is to mix the high thermal conductivity material, conductive agent, lithium ion conductive material, binder, dispersant and solvent evenly, and prepare the functional material layer slurry to be coated;

[0089] The second step is to use the micro-gravure coating method to coat the functional material layer slurry on one or both sides of the commercial diaphragm to obtain a composite diaphragm;

[0090] In the third step, the coated composite diaphragm is successively subjected to drying treatment, heat setting and winding operations.

[0091] It should be noted that the micro-gravure coating method is an existing common slurry coating method, and will not be repeated here.

[0092] It should be note...

Embodiment 1

[0115]A kind of preparation method of high security composite diaphragm provided by the present invention, the steps are as follows:

[0116] In the first step, a polyethylene (PE) separator with a thickness of 12 microns is selected as the coating base film. The coating slurry was prepared by using inorganic nano-thermal conductive material (hexagonal boron nitride), lithium lanthanum zirconate LLZO (as a lithium ion conducting material), carbon nanotube CNT, binder PAN, dispersant PVP, solvent NMP, etc. Wherein, the percentage by weight of solid raw materials for the coating slurry is as follows: 40% for inorganic nano heat-conducting material, 35% for LLZO, 5% for CNT, 15% for binder, and 5% for dispersant. The solvent of the slurry is NMP, and the solid content of the slurry is 10%. Use a centrifugal disperser to fully mix and disperse the above mixture evenly to obtain a mixed slurry;

[0117] The second step is to use the micro-gravure coating method to coat the separa...

Embodiment 2

[0120] A kind of preparation method of high security composite diaphragm provided by the present invention, the steps are as follows:

[0121] In the first step, a 16-micron thick polypropylene (PP) separator is selected as the coating base film. Use inorganic nano-thermal conductive materials (mixed materials of hexagonal boron nitride and alumina), lithium aluminum titanium phosphate LATP (as a lithium ion conductive material), graphene, binder PAN, dispersant PVP, solvent NMP, etc. to prepare coating slurry material. The percentage by weight of the solid raw materials for the coating slurry is as follows: 50% for the inorganic nano thermally conductive material, 30% for LATP, 5% for graphene, 13% for the binder, and 2% for the dispersant. The solvent of the slurry is NMP, and the solid content of the slurry is 15%. Use a centrifugal disperser to fully mix and disperse the above mixture evenly to obtain a mixed slurry;

[0122] The second step is to use the micro-gravure ...

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Abstract

The invention discloses a high-safety composite diaphragm. The diaphragm comprises a commercial diaphragm, wherein the single-side or double-side surface of the commercial diaphragm is coated with atleast one functional material layer; the commercial diaphragm is used for bearing and fixing the functional material layer; the functional material layer comprises a high-thermal-conductivity material, a conductive agent, a lithium ion conductive material, a binder and a dispersing agent. In addition, the invention also discloses a preparation method of the high-safety composite diaphragm. The method comprises the following steps: 1, uniformly mixing the high-thermal-conductivity material, the conductive agent, the lithium ion conductive material, the binder, the dispersing agent and the solvent to obtain functional material layer slurry; 2, performing single-sided or double-sided coating on the commercial diaphragm by using the functional material layer slurry in a micro-gravure coating mode to obtain a composite diaphragm; 3, sequentially carrying out drying treatment, heat setting and rolling operation on the composite diaphragm. Starting from two aspects of heat generation and heatconduction, heat accumulation caused by short circuit in the battery can be effectively inhibited, and thermal runaway is avoided.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a high-safety composite diaphragm and a preparation method thereof. Background technique [0002] During the use of lithium-ion battery cells, modules or systems, internal short circuits will occur under overcurrent, overcharge, internal lithium dendrites, extrusion, mechanical shock, puncture or other abuses. When the accumulated Joule heat cannot be quickly diffused and discharged, an exothermic chain reaction will occur, triggering an exothermic reaction of large-area negative electrodes, positive electrodes, electrolytes, separators and other materials, eventually leading to thermal runaway of lithium-ion batteries. [0003] At present, diaphragm regulation is a common method to suppress the internal short circuit of the battery. The polymer diaphragm is used as the base film, and the surface is coated with granular materials with high mechanical strength such a...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M2/14H01M10/613H01M10/653H01M10/654
CPCH01M10/613H01M10/653H01M10/654Y02E60/10
Inventor 周江孟繁慧李慧芳
Owner TIANJIN LISHEN BATTERY
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