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Diaphragm, preparation method thereof and lithium ion power battery comprising diaphragm

A separator and coating technology, applied in the field of lithium-ion power batteries, can solve the problems of small power cells with little effect, affecting normal use, reducing the electrical performance of the cells, and reducing the probability of thermal runaway and low cost. , the effect of enhancing thermal conductivity

Active Publication Date: 2020-08-28
ZHUHAI COSMX POWER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this solution is only suitable for consumer small-capacity batteries, and has little effect on power-type large batteries
Adding flame retardant additives to the electrolyte and adding a special coating on the surface of the pole piece can significantly improve the safety performance of the battery, but it will also significantly reduce the electrical performance of the battery, seriously affecting normal use.

Method used

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  • Diaphragm, preparation method thereof and lithium ion power battery comprising diaphragm
  • Diaphragm, preparation method thereof and lithium ion power battery comprising diaphragm
  • Diaphragm, preparation method thereof and lithium ion power battery comprising diaphragm

Examples

Experimental program
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specific Embodiment approach 1

[0033] A diaphragm, comprising a diaphragm base layer 1 and a PVDF coating 2, the PVDF coating 2 is arranged on one or both sides of the diaphragm base layer 1, the PVDF coating 2 includes PVDF and nano copper powder 21, the Nano copper powder 21 is dispersed in PVDF.

[0034] Further, the particle size of the nano-copper powder 21 is 1-200nm, preferably, the particle size is 1-50nm, and the specific surface area is 10-300m 2 / g, preferably 10-70m 2 / g.

[0035] Further, the thickness of the single side coating of the PVDF coating 2 is 1-3 μm.

[0036] Further, the mass of the nano-copper powder 21 accounts for 0.09%-5% of the mass of the PVDF coating 2 . The nano-copper powder 21 dispersed in PVDF forms a heat conduction network in the PVDF coating 2, as shown figure 1 and figure 2 The diaphragm structure shown in the figure can quickly transfer heat from the inside of the cell to the surface of the cell for heat dissipation.

[0037] Further, the diaphragm base layer ...

specific Embodiment approach 2

[0046] A method for preparing the diaphragm described in Embodiment 1, comprising the following steps:

[0047] S1. Add nano-copper powder 21 to absolute ethanol, ultrasonically 10-30min, fully wet, form mixture I, add dispersant to mixture I, and continue ultrasonicating for 20-90min, disperse evenly, and form suspended and stable nano copper powder dispersion;

[0048] S2. Add the nano-copper powder dispersion into the evenly stirred and dispersed PVDF solution, and use a stirrer to stir at a speed of 200-1000r / min for 30-60min, and disperse evenly to obtain a mixture II;

[0049]S3. Coating the mixture II on one or both sides of the base layer 1 of the diaphragm, drying in vacuum, the vacuum degree is 0.01Mpa-0.04Mpa, the drying temperature is 70-90°C, the drying time is 8h-12h, and the surface coating is obtained. The diaphragm base layer 1 coated with the PVDF coating 2, ie the diaphragm.

[0050] Further, in step S1, the solid content of the nano-copper powder dispersi...

specific Embodiment approach 3

[0054] A lithium-ion power battery, comprising the separator described in Embodiment 1 or the separator prepared by the method described in Embodiment 2, and the electrode sheet of the separator and the positive electrode ternary material / lithium iron phosphate material and the negative electrode graphite material Lamination, encapsulation, liquid injection, formation, secondary sealing, sorting and other processes are carried out to produce lithium-ion power batteries with high safety.

[0055] In order to verify the safety and practicability of the diaphragm, the examples all take 11A3W8-40Ah power type lithium ion power cell as the object, the positive electrode material is NCM ternary material, the negative electrode is graphite, and the electrolyte is conventional lithium ion electrolyte . The surface density of this power type cell is low, the internal resistance is small, and the heat generated instantaneously when the internal short circuit occurs during the acupunctur...

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Abstract

The invention provides a diaphragm, a preparation method thereof and a lithium ion power battery comprising the diaphragm in order to improve the needling safe passing performance of a battery cell and ensure that the electrical performance of the battery cell is not affected, and belongs to the technical field of batteries. According to the specific scheme, the diaphragm comprises a diaphragm substrate layer and a PVDF coating, wherein the PVDF coating is arranged on one side or two sides of the diaphragm substrate layer, the PVDF coating comprises PVDF and nano copper powder, and the nano copper powder is dispersed in the PVDF. According to the high-safety lithium ion power battery diaphragm provided by the invention, by adopting the ceramic diaphragm in which a trace amount of nano copper powder is mixed in the PVDF glue coating, the heat-conducting property of the diaphragm is greatly enhanced, the needling safety of the high-capacity lithium-ion power battery cell is effectively improved, particularly the safety of the power type lithium-ion power battery cell with low coating surface density is improved, and meanwhile, the electrical property of the battery cell is not influenced.

Description

technical field [0001] The invention relates to the technical field of battery materials, in particular to a diaphragm, a preparation method thereof, and a lithium ion power battery containing the diaphragm. Background technique [0002] Due to its high energy density, no memory effect, and long cycle life, lithium-ion batteries have been widely used in various mobile power supply devices, including consumer electronics, new energy vehicles, and energy storage devices. [0003] However, due to the high energy of lithium-ion batteries, accidents of fire and explosion caused by thermal runaway of lithium-ion batteries have occurred from time to time in recent years. Thermal runaway is caused by internal short circuit caused by thermal abuse, mechanical abuse, electrical abuse and other factors. The chemical energy stored in the battery is quickly converted into heat energy, which cannot be quickly released to the surface of the battery cell, resulting in excessive energy accum...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M10/0525
CPCH01M10/0525H01M50/40H01M50/431H01M50/411Y02E60/10
Inventor 李振靳玲玲王美丽凡小磊
Owner ZHUHAI COSMX POWER CO LTD
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