CN112467305B - High-flame-retardance high-heat-conductivity lithium battery diaphragm and preparation method thereof - Google Patents
High-flame-retardance high-heat-conductivity lithium battery diaphragm and preparation method thereof Download PDFInfo
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 36
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 36
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 239000003063 flame retardant Substances 0.000 claims abstract description 62
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229910052582 BN Inorganic materials 0.000 claims abstract description 21
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 claims abstract description 21
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims abstract description 21
- 239000003921 oil Substances 0.000 claims abstract description 21
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 claims abstract description 21
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 20
- 239000011258 core-shell material Substances 0.000 claims abstract description 18
- 239000006087 Silane Coupling Agent Substances 0.000 claims abstract description 13
- 239000000725 suspension Substances 0.000 claims abstract description 12
- XSAOTYCWGCRGCP-UHFFFAOYSA-K aluminum;diethylphosphinate Chemical compound [Al+3].CCP([O-])(=O)CC.CCP([O-])(=O)CC.CCP([O-])(=O)CC XSAOTYCWGCRGCP-UHFFFAOYSA-K 0.000 claims abstract description 11
- 238000001125 extrusion Methods 0.000 claims abstract description 10
- 238000002156 mixing Methods 0.000 claims abstract description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 6
- 238000009998 heat setting Methods 0.000 claims abstract description 6
- 238000005096 rolling process Methods 0.000 claims abstract description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 18
- 239000002245 particle Substances 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 11
- 238000005266 casting Methods 0.000 claims description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 6
- 125000004469 siloxy group Chemical group [SiH3]O* 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- 239000000835 fiber Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- -1 polysiloxane Polymers 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 238000009833 condensation Methods 0.000 claims description 3
- 230000005494 condensation Effects 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000011049 filling Methods 0.000 claims description 3
- 230000007062 hydrolysis Effects 0.000 claims description 3
- 238000006460 hydrolysis reaction Methods 0.000 claims description 3
- 229920001296 polysiloxane Polymers 0.000 claims description 3
- 238000000605 extraction Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 239000002131 composite material Substances 0.000 abstract description 7
- 239000011256 inorganic filler Substances 0.000 abstract description 2
- 229910003475 inorganic filler Inorganic materials 0.000 abstract description 2
- 239000000945 filler Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 6
- REBHQKBZDKXDMN-UHFFFAOYSA-M [PH2]([O-])=O.C(C)[Al+]CC Chemical compound [PH2]([O-])=O.C(C)[Al+]CC REBHQKBZDKXDMN-UHFFFAOYSA-M 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000002195 synergetic effect Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 206010000369 Accident Diseases 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241001460678 Napo <wasp> Species 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910001377 aluminum hypophosphite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- CQYBWJYIKCZXCN-UHFFFAOYSA-N diethylaluminum Chemical compound CC[Al]CC CQYBWJYIKCZXCN-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 230000003211 malignant effect Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a high-flame-retardance high-heat-conductivity lithium battery diaphragm and a preparation method thereof, wherein 5-10 parts of aluminum nitride, 1-3 parts of boron nitride, 1-3 parts of silicon carbide, 5-10 parts of a core-shell flame retardant, 1-3 parts of aluminum diethylphosphinate and 0.1-1 part of a silane coupling agent are placed in ethanol and stirred to form a suspension; and then mixing 20-40 parts of ultra-high molecular weight polyethylene with the two suspensions, drying, adding 60-80 parts of white oil, performing melt extrusion, performing biaxial stretching, extracting with the white oil, performing heat setting, and rolling to obtain the high-flame-retardant high-heat-conductivity lithium battery diaphragm. According to the invention, the composite flame-retardant system and the high-thermal-conductivity inorganic filler are added into the lithium battery diaphragm to form the flame-retardant network and the heat-conducting network connected by the bridge frame, so that the flame retardance and the thermal conductivity of the diaphragm are improved, and the safety problem of the lithium battery is solved from the two aspects of heat conduction and flame retardance.
Description
Technical Field
The invention relates to the technical field of lithium battery diaphragms, in particular to a high-flame-retardant high-heat-conductivity lithium battery diaphragm and a preparation method thereof.
Background
According to the lithium ion battery for EV, the energy density of the lithium ion battery is 300 Wh/kg before 2020 -1 Above, the battery pack level reaches 200 Wh/kg -1 This indicates that the cruising level of the electric vehicle can reach 400km or more. For power batteries, the number of lithium ion batteries in the battery pack is as many as several hundred or even ten thousand, which greatly improves the probability of safety risks. Because the energy contained in the power battery pack is extremely large, serious accidents are easily induced, and casualties and property loss are caused. The safe design of lithium batteries becomes a non-negligible key factor.
The lithium ion battery mainly comprises a positive electrode material, a negative electrode material, electrolyte, a diaphragm, a related content packaging material and the like. In case of fire, explosion and other accidents, the diaphragm and the electrolyte are the main inflammable matters. The related reports indicate that: the evacuation time of a passenger car is less than 30 seconds, while the evacuation time of a bus with the length of 12 meters is 5 minutes, the reserved escape time must be ensured, and no people are trapped during the accident. Therefore, there is a real need to improve the flame retardant property of lithium batteries.
At present, commercial diaphragms are mainly made of polyolefin high polymer materials or functional coatings are coated on the surfaces of the diaphragms, so that the diaphragms have the defect of poor flame retardance, are extremely easy to ignite once a fire accident happens, and have the risk of dripping and expanding the fire behavior; in addition, the thermal conductivity of the diaphragm produced in mass production at present is poor, and the diaphragm cannot well play a role in protection when thermal runaway occurs in the battery. The flame retardant property and the thermal conductivity of the lithium battery diaphragm are improved so as to enhance the safety of the lithium battery.
Disclosure of Invention
In order to solve the technical problems of poor flame retardance and poor thermal conductivity of polyolefin polymer diaphragms, a high-flame-retardance high-thermal-conductivity lithium battery diaphragm and a preparation method thereof are provided. According to the invention, the efficient, environment-friendly and synergistic flame retardant and the high-thermal-conductivity inorganic filler are added into the lithium battery diaphragm substrate, and the flame retardant and the thermal-conductivity filler are blended and dispersed in the diaphragm substrate to form a flame-retardant and thermal-conductivity network connected with a bridge frame, so that the flame retardance and the thermal conductivity of the diaphragm are improved.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following raw materials in parts by weight:
20-40 parts of ultra-high molecular weight polyethylene,
5-10 parts of aluminum nitride,
1-3 parts of boron nitride,
1-3 parts of silicon carbide,
5-10 parts of core-shell flame retardant,
1-3 parts of aluminum diethylphosphinate,
0.1-1 part of silane coupling agent.
Further, the molecular weight of the ultra-high molecular weight polyethylene is more than 150 ten thousand.
Further, the aluminum nitride is spherical aluminum nitride, and the particle size is 5-100 nm; the boron nitride is flaky boron nitride, and the particle size is less than 0.1-50 mu m; the silicon carbide is fibrous silicon carbide, the diameter of the fiber is 100-800 nm, and the length of the fiber is more than 100 mu m.
Furthermore, the core-shell flame retardant takes polysiloxane obtained by hydrolysis condensation of monofunctional siloxy groups and tetrafunctional siloxy groups as shell layers and red phosphorus as a core, the content of red phosphorus is more than 90 wt%, and the particle size is 0.1-50 um; the particle size of the aluminum diethylphosphinate is 5-50 um.
Further, the silane coupling agent is KH 172.
The invention also provides a preparation method of the high-flame-retardant high-heat-conductivity lithium battery diaphragm, which comprises the following steps:
(1) weighing aluminum nitride, boron nitride, silicon carbide, a core-shell flame retardant, aluminum diethylphosphinate and a silane coupling agent according to a ratio, placing the materials into ethanol, and stirring to form a flame-retardant high-thermal-conductivity suspension;
(2) weighing ultrahigh molecular weight polyethylene according to a ratio, adding the flame-retardant high-thermal-conductivity suspension, and fully mixing and drying to obtain a mixed material;
(3) putting the mixed material into an extruder, adding white oil from an oil filling port of the extruder, carrying out melt extrusion, extruding the mixture through a die orifice of the extruder to a casting sheet roller, and cooling the mixture to prepare a casting sheet; longitudinally stretching the casting sheet, and then transversely stretching to obtain an oil-containing film; extracting the white oil in the oil-containing film by adopting dichloromethane to obtain a microporous film; and finally, carrying out heat setting treatment, and rolling to obtain the high-flame-retardant high-heat-conductivity lithium battery diaphragm.
Further, the solid content of the flame-retardant heat-conducting suspension in the step (1) is 20-50 wt%; the mixing speed is 50rpm to 200rpm, and the mixing time is 10min to 40 min; the drying temperature in the step (2) is 50-80 ℃; and (4) adding the white oil in the step (3) in an amount which is 2-3 times of the weight of the ultrahigh molecular weight polyethylene.
Further, in the step (3), the extrusion temperature is 150-260 ℃, the screw rotation speed is 80-200 rpm, and the extrusion amount is 120-500 kg/h; the transverse stretching temperature is 80-150 ℃, and the transverse stretching multiple is 2-12 times; the extraction temperature of the dichloromethane is 5-20 ℃, and the flow rate is 1m 3 /h～8m 3 H; the heat setting temperatureIs 120 to 160 ℃.
The beneficial technical effects are as follows:
the invention develops a high-flame-retardant high-heat-conductivity lithium battery diaphragm by adopting a high-heat-conductivity network structure constructed by spherical aluminum nitride, flaky boron nitride and fibrous silicon carbide and a high-efficiency compound synergistic flame-retardant system consisting of aluminum diethylphosphinate and a core-shell flame retardant. Firstly dispersing a high-heat-conduction filler system and a flame-retardant system into a suspension with a certain solid content in a liquid state, then fully mixing the suspension with ultra-high molecular weight polyethylene, uniformly adhering the high-heat-conduction filler system and a composite flame-retardant system on the surface of the dried ultra-high molecular weight polyethylene, using white oil as a pore-forming agent, and performing shearing dispersion on the surfaces of a double screw in an extruder to uniformly disperse particles of the high-heat-conduction filler system and the composite flame-retardant system in a polyethylene matrix to form a sea-island structure, thereby generating special organic-inorganic hybrid characteristics. Because spherical aluminum nitride nano particles in the high-thermal-conductivity filler system have high thermal conductivity and large specific surface area, scattering points are formed in the diaphragm (the scattering points are difficult to form a thermal conduction path), and the spherical aluminum nitride scattering points are connected into the thermal conduction path through the two-dimensional flaky boron nitride and the one-dimensional fibrous silicon carbide as connecting bridges to form a three-dimensional thermal conduction network, so that the thermal conductivity and the temperature resistance of the diaphragm are greatly improved, and the internal thermal dissipation performance and the safety of the lithium battery are improved; in addition, the added inorganic particles of the high-thermal-conductivity filler system can stabilize the diaphragm structure, so that the short circuit problem caused by direct contact of the anode and the cathode due to deformation of the diaphragm at the initial stage of thermal runaway can be avoided, and the time for severe chemical reaction inside the diaphragm can be delayed. And once the fire is generated by violent chemical reaction inside the composite flame-retardant system, the core-shell flame retardant in the composite flame-retardant system decomposes to generate a viscous crusting isolator in the combustion process, and can play a role in isolating oxygen, heat and micromolecules in the combustion process, the aluminum diethylphosphinate plays a role in a condensed phase, the polymer is promoted to form carbon, the free radical generated by combustion is eliminated, the combustion reaction is blocked, the synergistic effect is played, and the flame-retardant performance is improved.
The invention solves the safety problem of the lithium battery from two aspects of heat conduction and flame retardance: the composite flame-retardant system disclosed by the invention has the advantages that the heat-conducting property of the diaphragm is improved, the internal heat dissipation of the battery is enhanced, the thermal stability of the battery is improved, the time of violent chemistry in the battery is delayed, the risk of thermal runaway under extreme conditions is controlled, and once the thermal runaway occurs, the composite flame-retardant system disclosed by the invention has an efficient and synergistic effect to improve the flame-retardant property of the lithium battery diaphragm, so that the purpose of enhancing the safety of a lithium battery component is achieved from two aspects, the precious escape time is strived for when the lithium battery has a safety accident, and the occurrence of a malignant accident is avoided.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless specifically stated otherwise, the numerical values set forth in these examples do not limit the scope of the invention. Techniques, methods known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
The experimental methods of the following examples, which are not specified under specific conditions, are generally determined according to national standards; if no corresponding national standard exists, the method is carried out according to the universal international standard or the standard requirement proposed by related enterprises. Unless otherwise indicated, all parts are parts by weight and all percentages are percentages by weight.
The ultra high molecular weight polyethylene, UHMWPE VH095, used in the following examples, was supplied by korea oiling company and had a molecular weight greater than 150 ten thousand. The white oil is prepared by mixingNo. 46 petrochemical product with kinematic viscosity (40 deg.C) of 43-49mm 2 A flash point of greater than 180 ℃. The spherical aluminum nitride is AM-ALN-071-1 produced by Yam technologies of Zhejiang, and has a particle size distribution of 5-40 nm. The used flaky boron nitride adopts NS-BN produced by Suzhou Napo material science and technology limited, and the particle size distribution of the flaky boron nitride is 0.2-50 mu m. The used fibrous silicon carbide adopts SiCW-98 produced by Qinhuang Yinuo high-new material development limited company, the fiber diameter is 100-600 nm, and the length is more than 100 μm. The adopted AP462 product produced by core-shell flame retardant Kelaien company takes polysiloxane which is obtained by hydrolysis condensation of monofunctional siloxy group and tetrafunctional siloxy group as a shell layer and red phosphorus as a core, the red phosphorus content is more than 90 wt%, the particle size is 0.1-50um, the effective content of the red phosphorus is more than 90 wt%, the particle size is 0.5-20 mu m, the flame retardant has high-efficiency flame retardance and good compatibility with ultrahigh molecular weight polyethylene. The diethyl aluminum hypophosphite is ADP produced by Wuhan Zhongcheng science and technology limited, and the particle size distribution of the ADP is 5-40 mu m.
Example 1
A high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following raw materials in parts by weight: 30 parts of ultra-high molecular weight polyethylene, 5 parts of aluminum nitride, 3 parts of boron nitride, 3 parts of silicon carbide, 8 parts of core-shell flame retardant, 2 parts of diethyl aluminum phosphinate and 0.5 part of silane coupling agent.
The preparation method of the high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following steps:
(1) weighing aluminum nitride, boron nitride, silicon carbide, a core-shell flame retardant, aluminum diethylphosphinate and a silane coupling agent according to a ratio, placing the materials into ethanol, and stirring to form a flame-retardant high-thermal-conductivity suspension liquid with the solid content of 30 wt%, wherein the stirring speed is 100rpm, and the stirring time is 30 min;
(2) weighing ultrahigh molecular weight polyethylene according to a ratio, adding the flame-retardant high-thermal-conductivity suspension, fully mixing, and drying at 80 ℃ to obtain a mixed material;
(3) putting the mixed material into an extruder, adding 70 parts by weight of white oil from an oil filling port of the extruder, carrying out melt extrusion, extruding the mixture through a die orifice of the extruder to a casting sheet roller, cooling the mixture to prepare a casting sheet, wherein the melt extrusion temperature is 220 ℃, the screw rotation speed is 90rpm, and the extrusion amount is 300 kg/h;
longitudinally stretching the casting sheet at 110 ℃ by 8 times, and then transversely stretching the casting sheet at 125 ℃ by 12 times to obtain an oil-containing film;
extracting the white oil in the oil-containing film by adopting dichloromethane to obtain a microporous film, wherein the temperature of the dichloromethane is 5 ℃, and the flow rate is 5m 3 /h；
And finally, carrying out heat setting treatment at the temperature of 140 ℃, and rolling to obtain the high-flame-retardant high-heat-conductivity lithium battery diaphragm.
Example 2
A high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following raw materials in parts by weight: 30 parts of ultra-high molecular weight polyethylene, 10 parts of aluminum nitride, 3 parts of boron nitride, 3 parts of silicon carbide, 8 parts of core-shell flame retardant, 2 parts of diethyl aluminum phosphinate and 0.5 part of silane coupling agent.
The preparation method is the same as that of example 1.
Example 3
A high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following raw materials in parts by weight: 30 parts of ultra-high molecular weight polyethylene, 10 parts of aluminum nitride, 1 part of boron nitride, 1 part of silicon carbide, 8 parts of core-shell flame retardant, 2 parts of diethyl aluminum phosphinate and 0.5 part of silane coupling agent.
The preparation method is the same as that of example 1.
Example 4
A high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following raw materials in parts by weight: 30 parts of ultra-high molecular weight polyethylene, 10 parts of aluminum nitride, 3 parts of boron nitride, 3 parts of silicon carbide, 5 parts of core-shell flame retardant, 2 parts of diethyl aluminum phosphinate and 0.5 part of silane coupling agent.
The preparation method is the same as that of example 1.
Example 5
A high-flame-retardant high-heat-conductivity lithium battery diaphragm comprises the following raw materials in parts by weight: 30 parts of ultra-high molecular weight polyethylene, 10 parts of aluminum nitride, 3 parts of boron nitride, 3 parts of silicon carbide, 8 parts of core-shell flame retardant, 1 part of diethyl aluminum phosphinate and 0.5 part of silane coupling agent.
The preparation method is the same as that of example 1.
Comparative example 1
Comparative example 1 is a single layer ultra high molecular weight polyethylene separator produced by a company using a wet process.
Taking the battery diaphragm prepared in the embodiment 1 to the embodiment 5, and testing the thermal shrinkage rate by adopting a vacuum oven dryer, wherein the testing temperature is 120 ℃, and the testing time is 30 min; testing the heat conductivity coefficient by adopting a heat conductivity coefficient tester; testing the limit oxygen index by using a limit combustion tester; the flame retardant rating was tested using a plastic flame retardant rating tester, while comparative example 1 was set as a blank control, and the test results are shown in table 1.
Table 1 performance of battery separators obtained in examples 1 to 5
According to the membrane performance detection results of the embodiments 1 to 3, the influence of the heat-conducting filler on the heat conductivity coefficient of the membrane is known, and when the boron nitride and the silicon carbide are used in a certain amount, the amount of the aluminum nitride is increased, and the heat conductivity coefficient is increased; when the dosage of the aluminum nitride is constant, the dosage of the boron nitride and the silicon carbide is reduced, and the heat conductivity coefficient is reduced. Compared with the example 2, the example 4 and the example 5, when the dosage of the heat-conducting filler is constant, the thermal shrinkage of the diaphragm is not obviously changed, the limiting oxygen index of the diaphragm is reduced when the dosage of the core-shell flame retardant is reduced, the flame retardance is poor, and when the dosage of the core-shell flame retardant is constant, the dosage of the aluminum diethylphosphinate is reduced, the flame retardance of the diaphragm is poor.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (7)
1. The high-flame-retardant high-heat-conductivity lithium battery diaphragm is characterized by comprising the following raw materials in parts by weight:
20-40 parts of ultra-high molecular weight polyethylene,
5-10 parts of aluminum nitride,
1-3 parts of boron nitride,
1-3 parts of silicon carbide,
5-10 parts of core-shell flame retardant,
1-3 parts of aluminum diethylphosphinate,
0.1-1 part of a silane coupling agent;
the aluminum nitride is spherical aluminum nitride, and the particle size is 5-100 nm; the boron nitride is flaky boron nitride, and the particle size is less than 0.1-50 mu m; the silicon carbide is fibrous silicon carbide, the diameter of the fiber is 100-800 nm, and the length of the fiber is more than 100 mu m.
2. The separator for a lithium battery as claimed in claim 1, wherein the molecular weight of the ultra-high molecular weight polyethylene is greater than 150 ten thousand.
3. The lithium battery diaphragm with high flame retardance and high heat conductivity as claimed in claim 1, wherein the core-shell flame retardant is prepared by taking polysiloxane obtained by hydrolysis condensation of a monofunctional siloxy group and a tetrafunctional siloxy group as a shell layer and red phosphorus as a core, the red phosphorus content is more than 90 wt%, and the particle size is 0.1-50 um; the particle size of the aluminum diethylphosphinate is 5-50 um.
4. The lithium battery separator with high flame retardance and high thermal conductivity as claimed in claim 1, wherein the silane coupling agent is KH 172.
5. The preparation method of the high-flame-retardant high-heat-conductivity lithium battery separator as claimed in any one of claims 1 to 4, characterized by comprising the following steps:
(1) weighing aluminum nitride, boron nitride, silicon carbide, a core-shell flame retardant, aluminum diethylphosphinate and a silane coupling agent according to a ratio, placing the materials into ethanol, and stirring to form a flame-retardant high-thermal-conductivity suspension;
(2) weighing ultrahigh molecular weight polyethylene according to a ratio, adding the flame-retardant high-thermal-conductivity suspension, and fully mixing and drying to obtain a mixed material;
(3) putting the mixed material into an extruder, adding white oil from an oil filling port of the extruder, carrying out melt extrusion, extruding the mixture through a die orifice of the extruder to a casting sheet roller, and cooling the mixture to prepare a casting sheet; longitudinally stretching the casting sheet, and then transversely stretching to obtain an oil-containing film; extracting the white oil in the oil-containing film by adopting dichloromethane to obtain a microporous film; and finally, carrying out heat setting treatment, and rolling to obtain the high-flame-retardant high-heat-conductivity lithium battery diaphragm.
6. The preparation method according to claim 5, wherein the solid content of the flame-retardant high-thermal-conductivity suspension in the step (1) is 20-50 wt%; the mixing speed is 50rpm to 200rpm, and the mixing time is 10min to 40 min; the drying temperature in the step (2) is 50-80 ℃; and (4) adding the white oil in the step (3) in an amount which is 2-3 times of the weight of the ultrahigh molecular weight polyethylene.
7. The production method according to claim 5, wherein the extrusion temperature in the step (3) is 150 to 260 ℃, the screw rotation speed is 80 to 200rpm, and the extrusion amount is 120 to 500 kg/h; the longitudinal stretching temperature is 80-150 ℃, and the longitudinal stretching multiple is 2-8 times; the transverse stretching temperature is 80-150 ℃, and the transverse stretching multiple is 2-12 times; the extraction temperature of the dichloromethane is 5-20 ℃, and the flow rate is 1-8 m of heavy plantation/h; the heat setting temperature is 120-160 ℃.
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| CN108034256A (en) * | 2017-12-01 | 2018-05-15 | 青岛德通纳米技术有限公司 | A kind of explosion-proof silica gel pad of high heat conduction low-gravity lithium battery and preparation method thereof |
| CN110112353A (en) * | 2018-02-01 | 2019-08-09 | 三星Sdi株式会社 | Diaphragm, using its lithium battery and diaphragm manufacturing method |
| CN110911620A (en) * | 2019-10-19 | 2020-03-24 | 东莞东阳光科研发有限公司 | Spotted coating diaphragm slurry, composite diaphragm and preparation method thereof |
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| CN108034256A (en) * | 2017-12-01 | 2018-05-15 | 青岛德通纳米技术有限公司 | A kind of explosion-proof silica gel pad of high heat conduction low-gravity lithium battery and preparation method thereof |
| CN110112353A (en) * | 2018-02-01 | 2019-08-09 | 三星Sdi株式会社 | Diaphragm, using its lithium battery and diaphragm manufacturing method |
| CN110911620A (en) * | 2019-10-19 | 2020-03-24 | 东莞东阳光科研发有限公司 | Spotted coating diaphragm slurry, composite diaphragm and preparation method thereof |
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