CN115636993B - Polyolefin powder, extrusion molding material, separator, battery, electronic device, and mobile device - Google Patents
Polyolefin powder, extrusion molding material, separator, battery, electronic device, and mobile device Download PDFInfo
- Publication number
- CN115636993B CN115636993B CN202110819888.1A CN202110819888A CN115636993B CN 115636993 B CN115636993 B CN 115636993B CN 202110819888 A CN202110819888 A CN 202110819888A CN 115636993 B CN115636993 B CN 115636993B
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- CN
- China
- Prior art keywords
- polyolefin
- polyolefin powder
- coating
- separator
- temperature
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- 229920000098 polyolefin Polymers 0.000 title claims abstract description 314
- 239000000843 powder Substances 0.000 title claims abstract description 200
- 238000001125 extrusion Methods 0.000 title claims description 41
- 239000012778 molding material Substances 0.000 title claims description 11
- 239000002245 particle Substances 0.000 claims abstract description 110
- 239000000463 material Substances 0.000 claims abstract description 52
- 239000000155 melt Substances 0.000 claims abstract description 35
- 238000002425 crystallisation Methods 0.000 claims abstract description 32
- 230000008025 crystallization Effects 0.000 claims abstract description 32
- 238000004383 yellowing Methods 0.000 claims abstract description 17
- 238000000576 coating method Methods 0.000 claims description 92
- 239000011248 coating agent Substances 0.000 claims description 91
- 238000012360 testing method Methods 0.000 claims description 62
- 239000000203 mixture Substances 0.000 claims description 49
- 239000000758 substrate Substances 0.000 claims description 42
- 238000010438 heat treatment Methods 0.000 claims description 41
- 238000012545 processing Methods 0.000 claims description 34
- 238000002844 melting Methods 0.000 claims description 32
- 230000008018 melting Effects 0.000 claims description 32
- 238000001816 cooling Methods 0.000 claims description 27
- 239000012528 membrane Substances 0.000 claims description 24
- 229920001577 copolymer Polymers 0.000 claims description 22
- 239000004014 plasticizer Substances 0.000 claims description 21
- 238000004519 manufacturing process Methods 0.000 claims description 19
- -1 polyethylene-propylene copolymer Polymers 0.000 claims description 19
- 229920001038 ethylene copolymer Polymers 0.000 claims description 15
- 238000002156 mixing Methods 0.000 claims description 15
- 239000002033 PVDF binder Substances 0.000 claims description 13
- 239000002480 mineral oil Substances 0.000 claims description 13
- 235000010446 mineral oil Nutrition 0.000 claims description 13
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 13
- 238000009998 heat setting Methods 0.000 claims description 12
- 238000005259 measurement Methods 0.000 claims description 12
- 230000007246 mechanism Effects 0.000 claims description 11
- 229910052582 BN Inorganic materials 0.000 claims description 9
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims description 9
- 229910001593 boehmite Inorganic materials 0.000 claims description 8
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 8
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 6
- 239000005977 Ethylene Substances 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 6
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims description 6
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000000178 monomer Substances 0.000 claims description 5
- 230000009467 reduction Effects 0.000 claims description 5
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 4
- 239000004760 aramid Substances 0.000 claims description 4
- 229920003235 aromatic polyamide Polymers 0.000 claims description 4
- 238000005524 ceramic coating Methods 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 239000003792 electrolyte Substances 0.000 claims description 4
- 238000005096 rolling process Methods 0.000 claims description 4
- FRWYFWZENXDZMU-UHFFFAOYSA-N 2-iodoquinoline Chemical compound C1=CC=CC2=NC(I)=CC=C21 FRWYFWZENXDZMU-UHFFFAOYSA-N 0.000 claims description 3
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims description 3
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 3
- 229910052586 apatite Inorganic materials 0.000 claims description 3
- LTPBRCUWZOMYOC-UHFFFAOYSA-N beryllium oxide Inorganic materials O=[Be] LTPBRCUWZOMYOC-UHFFFAOYSA-N 0.000 claims description 3
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 3
- 239000000292 calcium oxide Substances 0.000 claims description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 3
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 3
- 239000000347 magnesium hydroxide Substances 0.000 claims description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 3
- 239000000395 magnesium oxide Substances 0.000 claims description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 3
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 claims description 3
- 238000007254 oxidation reaction Methods 0.000 claims description 3
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 claims description 3
- 230000010287 polarization Effects 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 3
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 claims description 3
- 229910003452 thorium oxide Inorganic materials 0.000 claims description 3
- 239000011787 zinc oxide Substances 0.000 claims description 3
- 239000004693 Polybenzimidazole Substances 0.000 claims description 2
- 239000004695 Polyether sulfone Substances 0.000 claims description 2
- 239000004697 Polyetherimide Substances 0.000 claims description 2
- 239000004698 Polyethylene Substances 0.000 claims description 2
- 239000004642 Polyimide Substances 0.000 claims description 2
- 239000004793 Polystyrene Substances 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 239000012298 atmosphere Substances 0.000 claims description 2
- 239000002131 composite material Substances 0.000 claims description 2
- 229920001519 homopolymer Polymers 0.000 claims description 2
- 239000010445 mica Substances 0.000 claims description 2
- 229910052618 mica group Inorganic materials 0.000 claims description 2
- 239000002808 molecular sieve Substances 0.000 claims description 2
- 229920001643 poly(ether ketone) Polymers 0.000 claims description 2
- 229920002492 poly(sulfone) Polymers 0.000 claims description 2
- 229920000058 polyacrylate Polymers 0.000 claims description 2
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 2
- 229920001230 polyarylate Polymers 0.000 claims description 2
- 229920002480 polybenzimidazole Polymers 0.000 claims description 2
- 229920001690 polydopamine Polymers 0.000 claims description 2
- 229920000728 polyester Polymers 0.000 claims description 2
- 229920006393 polyether sulfone Polymers 0.000 claims description 2
- 229920001601 polyetherimide Polymers 0.000 claims description 2
- 229920000573 polyethylene Polymers 0.000 claims description 2
- 229920001721 polyimide Polymers 0.000 claims description 2
- 229920002223 polystyrene Polymers 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 2
- 238000012546 transfer Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 43
- 239000011148 porous material Substances 0.000 abstract description 15
- 230000008569 process Effects 0.000 abstract description 14
- 238000009826 distribution Methods 0.000 abstract description 12
- 230000007547 defect Effects 0.000 abstract description 10
- 239000003963 antioxidant agent Substances 0.000 description 41
- 230000003078 antioxidant effect Effects 0.000 description 41
- 238000005070 sampling Methods 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 12
- 239000010954 inorganic particle Substances 0.000 description 12
- 239000007774 positive electrode material Substances 0.000 description 10
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 9
- 239000007773 negative electrode material Substances 0.000 description 9
- 230000008961 swelling Effects 0.000 description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 238000005266 casting Methods 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- 239000011267 electrode slurry Substances 0.000 description 6
- 238000006864 oxidative decomposition reaction Methods 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 5
- 238000005227 gel permeation chromatography Methods 0.000 description 5
- 229940057995 liquid paraffin Drugs 0.000 description 5
- 239000012982 microporous membrane Substances 0.000 description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- IRIAEXORFWYRCZ-UHFFFAOYSA-N Butylbenzyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCC1=CC=CC=C1 IRIAEXORFWYRCZ-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 3
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000004880 explosion Methods 0.000 description 3
- 238000004898 kneading Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 229920005672 polyolefin resin Polymers 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- BJQHLKABXJIVAM-UHFFFAOYSA-N Diethylhexyl phthalate Natural products CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 150000008052 alkyl sulfonates Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- NNBZCPXTIHJBJL-UHFFFAOYSA-N decalin Chemical compound C1CCCC2CCCCC21 NNBZCPXTIHJBJL-UHFFFAOYSA-N 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- HBGGXOJOCNVPFY-UHFFFAOYSA-N diisononyl phthalate Chemical compound CC(C)CCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCC(C)C HBGGXOJOCNVPFY-UHFFFAOYSA-N 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005485 electric heating Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000037427 ion transport Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000005461 lubrication Methods 0.000 description 2
- HQKMJHAJHXVSDF-UHFFFAOYSA-L magnesium stearate Chemical compound [Mg+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O HQKMJHAJHXVSDF-UHFFFAOYSA-L 0.000 description 2
- 238000010309 melting process Methods 0.000 description 2
- DJDSLBVSSOQSLW-UHFFFAOYSA-N mono(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(O)=O DJDSLBVSSOQSLW-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002667 nucleating agent Substances 0.000 description 2
- 239000012188 paraffin wax Substances 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 230000000379 polymerizing effect Effects 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 239000010979 ruby Substances 0.000 description 2
- 229910001750 ruby Inorganic materials 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 150000003384 small molecules Chemical class 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 1
- 239000006245 Carbon black Super-P Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 229940045714 alkyl sulfonate alkylating agent Drugs 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 description 1
- 235000013539 calcium stearate Nutrition 0.000 description 1
- 239000008116 calcium stearate Substances 0.000 description 1
- 238000003490 calendering Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 229920006184 cellulose methylcellulose Polymers 0.000 description 1
- 239000012986 chain transfer agent Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010622 cold drawing Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N hexane Substances CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 239000004611 light stabiliser Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 235000019359 magnesium stearate Nutrition 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- AQSJGOWTSHOLKH-UHFFFAOYSA-N phosphite(3-) Chemical class [O-]P([O-])[O-] AQSJGOWTSHOLKH-UHFFFAOYSA-N 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
- PXXNTAGJWPJAGM-UHFFFAOYSA-N vertaline Natural products C1C2C=3C=C(OC)C(OC)=CC=3OC(C=C3)=CC=C3CCC(=O)OC1CC1N2CCCC1 PXXNTAGJWPJAGM-UHFFFAOYSA-N 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Classifications
-
- 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
Landscapes
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Cell Separators (AREA)
Abstract
The polyolefin powder is easy to process, resistant to yellowing, excellent in film forming quality, and meanwhile low in closed pore temperature and high in film breaking temperature. The polyolefin powder of the present application has a viscosity average molecular weight Mv of 15X 10 4 Above 300×10 4 The initial crystallization temperature is more than 108 ℃ and less than 120 ℃, the yellowing resistance Mv1/Mv is more than or equal to 0.75, the polyolefin powder contains 10-30wt% of polyolefin powder with the particle size of more than 110um, the melt index is 10-30 g/10min, the content of polyolefin powder with the particle size of less than 70um is 70-90 wt% and the melt index is less than or equal to 0.5g/10min. The anti-yellowing capability and the particle size distribution of the polyolefin powder are adjusted, so that the bright spot defect of the formed film material is improved, and the safety of the battery cell can be improved.
Description
Technical Field
The present application relates to the technical field of polyolefin, extrusion molding materials and lithium ion batteries, and in particular, to a separator, a manufacturing method thereof, a battery, electronic equipment and a mobile device.
Background
The polyolefin material is a thermoplastic resin prepared by polymerizing olefin monomers, has excellent low temperature resistance and good chemical stability, and can resist most of acid and alkali corrosion. Is insoluble in common solvent at normal temperature, does not absorb water, and has excellent electrical insulation property. Therefore, they are widely used as separators in lithium ion batteries.
Lithium ion batteries are now the secondary power source that is commercialized and widely used. In lithium ion batteries, polyolefin microporous membranes are porous, electrochemically inert media between the positive and negative electrodes that do not participate in the electrochemical reaction, but are critical to the safety performance of the cell. The polyolefin microporous membranes currently in use may have some drawbacks. For example, the separator may have poor ductility, which may lead to the separator being pierced when the cell is mechanically abused. As another example, the cell temperature of the separator is high, so that the electrochemical path is more difficult to shut off when the cell is overheated. As another example, the membrane rupture temperature of the membrane is low, such that the membrane melts when the cell overheats. Meanwhile, the polyolefin microporous membrane has serious defects of reduced film forming quality, such as bright spots, mildew spots and the like, caused by uneven plasticization in the processing process. The above defects easily cause breakage of the separator, and form a short-circuit point between the positive electrode and the negative electrode, thereby causing potential safety hazard.
In order to be used more safely and more efficiently in this field, extrusion molding characteristics of polyolefin materials have been intensively studied, and from the viewpoint of improving productivity, for example, methods like patent documents 1 and 2 are disclosed, and specifically, CN111848844a discloses a polyolefin material which has high strength, low heat shrinkage properties while improving production efficiency by controlling isothermal crystallization time of polyolefin, and a method for producing the same; CN111868113a discloses an excessive polyolefin resin and a method for preparing the same, wherein the excessive polyolefin material has high strength, high wear resistance, lubricity and chemical resistance, and simultaneously, the appearance and the oil smoke amount of the polyolefin material are improved by controlling the viscosity average molecular weight and the particle size of polyolefin powder.
In the field of lithium ion battery applications, attention is paid to the membrane forming quality, such as occurrence of bright spot defects, in addition to the strength, elongation at break, closed pores and membrane rupture characteristics of polyolefin microporous membranes. The polyolefin resin and the preparation method thereof disclosed in the patent literature only improve the appearance, the processing efficiency and the antioxidant capacity of the polyolefin resin by discussing isothermal crystallization time, viscosity average molecular weight and powder particle size distribution of the material, and do not provide a reasonable solution for the problem of bright spots generated in the polyolefin processing process and simultaneously realize high extensibility.
In addition, compared with the conventional polyolefin material, the polyolefin has the advantages that the high-low molecular weight collocation (the difference of melt indexes) is realized through the molecular weight design, the crystallization orientation of the high-molecular weight polyolefin material is realized in the processing process, meanwhile, the stress concentration in the stretching process is reduced due to the high lubrication characteristic of the low-molecular polyolefin, the residual stress is reduced, and the polyolefin microporous membrane with the characteristics of high modulus, high ductility, lower closed pore temperature and higher rupture temperature is realized. The design of the high molecular weight polyolefin material with small grain diameter and the low molecular weight polyolefin material with large grain diameter solves the problem of inconsistent swelling rate of the high/low molecular weight polyolefin materials, so that the polyolefin powder fully opens molecular chain entanglement in the high-temperature melting and blending process of an extruder, the melt non-uniformity is improved, the number of crystal points is reduced, and the defect of bright spots generated by unmelted high molecular weight polyolefin is solved. Meanwhile, the decrease of the viscosity average molecular weight of the polyolefin under the yellowing condition is controlled, so that the local degradation caused by the breakage of polyolefin molecular chains due to high temperature is prevented, and the second type of bright spot defect generated by thinner film surface thickness is prevented.
Disclosure of Invention
The present invention provides a polyolefin powder, an extrusion molding material, a separator, a method for producing the same, a battery, an electronic device, and a mobile device using the separator, and aims to provide a polyolefin powder which has improved uniformity of swelling rate, improved film surface hot spots, easy processing, low stress residual, high strength, and high modulus.
The present invention has been made to solve the above problems, and as a result of intensive studies, it has been found that the above problems can be solved by using the following specific polyolefin materials.
In a first aspect, there is provided a polyolefin powder comprising, the polyolefin powder having a viscosity average molecular weight Mv of 15X 10 4 Above 300×10 4 Wherein the initial crystallization temperature of the polyolefin powder is 108 ℃ to 120 ℃ by using a hot stage polarization microscope under the following measurement conditions,
measurement conditions of a polarizing microscope:
heating the heat table to 200 ℃ at a heating rate of 10 ℃/min, and maintaining for 3min;
the temperature of the hot table is reduced from 200 ℃ to 130 ℃ at a temperature reduction rate of-10 ℃/min;
cooling the temperature of the hot table from 130 ℃ to 120 ℃ at a cooling rate of-5 ℃/min;
cooling the temperature of the hot table from 130 ℃ to 118 ℃ at a cooling rate of-2 ℃/min;
cooling the temperature of the hot stage from 118 ℃ to 110 ℃ at a cooling rate of-0.5 ℃/min;
the temperature at which the polyolefin melt starts to crystallize under a polarizing microscope is defined as the initial crystallization temperature.
With reference to the first aspect, in certain implementations of the first aspect, the polyolefin powder has a viscosity average molecular weight Mv that satisfies the following relationship with a viscosity average molecular weight Mv1 of a polyolefin obtained by oxidation under (anaerobic) yellowing conditions,
Mv1/Mv≥0.75，
Yellowing conditions:
blending 30wt% polyolefin powder with 70wt% mineral oil;
placing the blend on a heating platform, and keeping the temperature at 40 ℃ for 0.5h;
heating the heating platform to 150 ℃ at a heating rate of 10 ℃/min, and maintaining for 0.5h;
the heating platen was heated to 200 ℃ at a ramp rate of 5 ℃/min and maintained for 1 hour.
With reference to the first aspect, in certain implementations of the first aspect, the polyolefin powder has a partial melt index (190 ℃/21.6 kg) of greater than or equal to 110um and a melt index (190 ℃/21.6 kg) of less than or equal to 70um and is 10 to 30g/10 min.
With reference to the first aspect, in certain implementations of the first aspect, when the polyolefin powder mass fraction is 100wt%, the polyolefin powder contains a polyolefin powder content of above 110um in an amount of 10-30 wt%, and a polyolefin powder content of below 70um in an amount of 70-90 wt%.
With reference to the first aspect, in certain implementations of the first aspect, the polyolefin powderBulk density of the fraction having a final particle diameter of 110um or more is 0.15 to 0.4g/cm 3 The bulk density of the polyolefin powder having a particle size of 70um or less is 0.5 to 0.8g/cm 3 。
With reference to the first aspect, in certain implementations of the first aspect, the polyolefin powder, after melting, has a resulting material density of 0.92g/cm 3 Above and 0.97g/cm 3 The following is given.
In a second aspect, there is provided an extrusion molding material in which the polyolefin powder according to the above-described implementation is processed and molded.
With reference to the second aspect, in certain implementations of the second aspect, the extrusion molding material is a microporous membrane.
With reference to the second aspect, in certain implementations of the second aspect, the separator is formed by processing the polyolefin powder according to the above implementations.
In a third aspect, a separator is provided that has a primary heat-up crystallinity of less than or equal to 72% and a secondary heat-up crystallinity of less than or equal to 55% as measured using a Differential Scanning Calorimeter (DSC).
With reference to the third aspect, in certain implementations of the third aspect, the separator further includes a separator coating disposed on one or both sides of the separator substrate.
With reference to the third aspect, in certain implementations of the third aspect, the separator coating includes one or more of an organic coating, an inorganic coating, and an organic-inorganic composite coating.
With reference to the third aspect, in certain implementations of the third aspect, the inorganic coating includes a ceramic coating including at least one of: alumina, silica, titania, zirconia, zinc oxide, barium oxide, magnesium oxide, beryllium oxide, calcium oxide, thorium oxide, aluminum nitride, titanium nitride, boehmite, apatite, aluminum hydroxide, magnesium hydroxide, barium sulfate, boron nitride, silicon carbide, silicon nitride, cubic boron nitride, hexagonal boron nitride, mesoporous molecular sieves (MCM-41, sba-15), and nacreous mica layers.
With reference to the third aspect, in certain implementations of the third aspect, the organic coating includes at least one of: polyvinylidene fluoride coating, vinylidene fluoride-hexafluoropropylene copolymer coating, polystyrene coating, aramid coating, polyacrylate or modified coating, polyester coating, polyarylate coating, polyacrylonitrile coating, aromatic polyamide coating, polyimide coating, polyethersulfone coating, polysulfone coating, polyetherketone coating, polyetherimide coating, polybenzimidazole coating, polydopamine coating.
In a fourth aspect, there is provided a battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator according to any one of the embodiments above.
In a fifth aspect, there is provided an electronic device comprising a housing, and a display screen, a circuit board assembly and a battery as described in the fourth aspect housed within the housing, the battery powering the display screen and the circuit board assembly.
In a sixth aspect, there is provided a mobile device comprising a battery as described in the fourth aspect.
In a seventh aspect, there is provided a method of manufacturing a separator, comprising:
mixing a mixture comprising a plasticizer, a polyolefin composition comprising a plurality of polyethylenes having different viscosity average molecular weights, and extruding from a screw extruder to form a gel sheet;
Biaxially stretching the gel sheet;
removing plasticizer from the gel sheet;
heat setting the gel sheet, wherein the heat setting comprises low-rate stretching and retracting operations;
and rolling and cutting the gel sheet to form the diaphragm.
The invention has the beneficial effects of providing the polyolefin powder which has the advantages of consistent swelling rate, improved bright spots on the surface of the film, easy processing, low stress residue, high strength and high modulus, and simultaneously has the characteristics of lower closed pore temperature and higher rupture temperature after being processed into the film.
Drawings
FIG. 1 is a twin screw extrusion die of the present application.
Detailed Description
The method of the present invention will be described in detail below, but the present invention is not limited thereto. Various optimizations can be made without departing from the technical scope thereof.
Viscosity average molecular weight
The polyolefin powder of the present application has a viscosity average molecular weight of 15X 10 4 Above 300×10 4 The following is given. From the viewpoint of processing molding and plasticizing, the viscosity average molecular weight is preferably 20X 10 4 200X 10 of the above 4 Hereinafter, it is more preferable to use a range of 25X 10 4 Above and 150×10 4 Within the following range, more preferably 25X 10 4 130×10 of the above 4 The following is given. The viscosity average molecular weight in the present application was measured by gel permeation chromatography (gel permeation chromatography, GPC). The polyolefin powder preferably has a viscosity average molecular weight of 15X 10 from the viewpoint of improving the strength of the polyolefin molding material while reducing the residual stress and improving the heat stability 4 From the viewpoint of improving the uniformity of the high-temperature melt of the polyolefin and improving the plasticization uniformity, the viscosity average molecular weight of the polyolefin powder is preferably 300X 10 4 The following is given.
The polyolefin powder of the present application is preferably at least one of an ethylene homopolymer or a polyethylene-propylene copolymer, a derivative of a polyethylene-propylene copolymer, a polyethylene-butene copolymer, a derivative of a polyethylene-butene copolymer, a polyethylene-hexene copolymer, a derivative of a polyolefin-hexene copolymer, a polyolefin-octene copolymer, a derivative of a polyolefin-octene copolymer, a polystyrene-ethylene-styrene copolymer, a derivative of a polystyrene-ethylene-styrene copolymer, a polystyrene-ethylene-butene-styrene copolymer, a derivative of a polystyrene-ethylene-butene-styrene copolymer, a polyolefin-hydrogenated oligocyclopentadiene, a derivative of a polyolefin-hydrogenated oligocyclopentadiene, polyethylene oxide, a derivative of polyethylene oxide, a polypentene-ethylene copolymer, a derivative of a polypentene-ethylene copolymer, a polyhexene-ethylene copolymer, a derivative of a polyhexene-ethylene copolymer, a polymethylpentene-ethylene copolymer, a derivative of a polymethylpentene-ethylene copolymer.
The ethylene monomer content in the ethylene copolymer of the present application is preferably 3wt% or more and 20wt% or less, more preferably 5wt% or more and 15wt% or less, and still more preferably 7wt% or more and 12wt% or less. The ethylene monomer content in the ethylene copolymer is preferably 3% by weight or more from the viewpoint of promoting melt compatibility, and 20% by weight or less from the viewpoint of improving the strength of the extrusion molded material.
The polyolefin powder in the application adopts a conventional polyolefin synthesis control method to adjust the viscosity average molecular weight, such as the conditions of temperature, pressure and the like in a polymerization system. The polymerization temperature is inversely related to the viscosity average molecular weight, i.e., the higher the polymerization temperature, the less favorable the polyolefin molecular weight increase. As a method for adjusting the viscosity average molecular weight of the polyolefin to the above range, there can be exemplified a method in which a metal material as a catalyst capable of polymerizing an ethylene monomer is used and polymerized to the target upper limit of the viscosity average molecular weight, and a chain transfer agent is added to reduce the viscosity average molecular weight of a part of the high molecular weight polyolefin to form a polyolefin material having a high and low molecular weight.
The present application contributes to the effect of the present application by determining the initial crystallization temperature of the polyolefin powder using a hot stage polarization microscope (LEICA DM 2500P) under the following measurement conditions, improving the uniformity of crystal growth thereof.
Test conditions:
heating the heat table to 200 ℃ at a heating rate of 10 ℃/min, and maintaining for 3min; the temperature of the hot table is reduced from 200 ℃ to 130 ℃ at a temperature reduction rate of-10 ℃/min; cooling the temperature of the hot table from 130 ℃ to 120 ℃ at a cooling rate of-5 ℃/min; cooling the temperature of the hot table from 130 ℃ to 118 ℃ at a cooling rate of-2 ℃/min; the temperature of the hot stage is reduced from 118 ℃ to 110 ℃ at a temperature reduction rate of-0.5 ℃/min, and the temperature at which the polyolefin melt starts to crystallize under a polarizing microscope is defined as the initial crystallization temperature.
It should be noted that the effect of the step-up/down rate is to release the residual stress in the polyolefin after the polyolefin is fully melted, eliminate the influence on crystallization behavior, and achieve isothermal crystallization effect.
Yellowing conditions:
blending 30wt% polyolefin powder with 70wt% mineral oil; placing the blend on a heating platform, and keeping the temperature at 40 ℃ for 0.5h; heating the heating platform to 150 ℃ at a heating rate of 10 ℃/min, and maintaining for 0.5h; the heating platen was heated to 200 ℃ at a ramp rate of 5 ℃/min and maintained for 1 hour.
In the present application, an antioxidant, a stabilizer, etc. may be introduced during the blending of 30wt% of the polyolefin powder with 70wt% of the mineral oil, and there is no particular limitation, such as phenols, amines, phosphites, thiodipropionates, etc.; stabilizing agent: such as sodium stearate, calcium stearate, magnesium stearate, zinc stearate, and the like; antistatic agents, radiation light absorbers, light stabilizers, nucleating agents, inorganic particles, and the like.
According to the embodiment of the application, mineral oil is used as a plasticizer, so that polyolefin is heated uniformly in the high-temperature melting process, the uniformity of a melt is improved, and the oxidative decomposition of a molecular chain caused by local thermal abnormality is reduced. The mineral oil used comprises any one or more of hydrocarbon organic solvents (such as paraffin, etc.), 2-ethylhexyl phthalate, dibutyl phthalate, alkyl sulfonate, butyl benzyl phthalate, diisononyl phthalate, etc.
Mv1/Mv
The polyolefin powder of the present application should satisfy the following relationship with the viscosity average molecular weight of the initial polyolefin powder under the above-mentioned yellowing conditions.
The Mv1/Mv is 0.75 or more, more preferably 0.8 or more, and still more preferably 0.85 or more. The ratio of Mv1/Mv is not particularly limited, but is preferably 0.98 or less, for example, indicating that the polyolefin powder is not oxidized at a high Wen Huanghua level.
According to the method, the Mv1/Mv is controlled to be more than 0.75, so that the high-temperature volatilization of a part with a higher melt index in polyolefin is reduced; on the other hand, the oxidative decomposition of the lower melt index portion (high molecular weight portion), such as the oxidative decomposition of the high molecular weight portion, is suppressed, and carbonized inorganic matters are dispersed in the melt, so that the formation of inorganic nucleating agents causes the crystallization disorder during the casting of the melt to affect the appearance. The polyolefin material designed by the embodiment is not easy to generate carbonization phenomenon, thereby promoting the consistency of high-temperature melt and improving the production efficiency. In addition, from the viewpoint of plasticizing ability and plasticizing uniformity of the polyolefin material with mineral oil, the ratio of Mv1/Mv is preferably 0.98 or less, more preferably 0.95 or less, and still more preferably 0.92 or less.
Particle size distribution and melt index
The polyolefin powder in the present application contains a fraction having a particle diameter of 110 μm or more, and has a melt index of 10g/10min or more, more preferably 15g/10min or more, still more preferably 18g/10min or more. The melt index of the portion having a particle size of 110um or more is 10g/10min or more from the viewpoint of improving the intermolecular lubrication and plasticization, and the melt index of the portion having a particle size of 110um or more is 30g/10min or less, more preferably 25g/10min or less, still more preferably 22g/10min or less from the viewpoint of improving the material strength and ease of processing.
The polyolefin powder in the present application contains a fraction having a particle size of 70 μm or less, and has a melt index of 0.5g/10min or less, more preferably 0.3g/10min or less, and still more preferably 0.25g/10min or less. The melt index of the portion having a particle diameter of 70um or less is 0.05g/10min or more from the viewpoint of optimizing the blending process, and the melt index of the portion having a particle diameter of 70um or less is 0.1g/10min or more, more preferably 0.12g/10min or more, still more preferably 15g/10min or more from the viewpoint of reducing the possibility of plasticization failure of the extrusion molding material, reducing the number of melt crystal points in the melt and improving the appearance quality.
The average particle diameter of the high melt index portion in the polyolefin powder of the present application is preferably 110 to 500um, more preferably 250 to 420um, still more preferably 270 to 380 um; the average particle diameter of the low melt index portion is preferably 70um or less and 10um or more, more preferably 60um or less and 20um or more, and still more preferably 55um or less and 25um or more. The average particle diameter of the high melt index portion is preferably 500um or less from the viewpoint of improving uniformity of crystal nucleus growth and uniformity of refractive index on a macro scale, and is preferably 110um or more from the viewpoint of matching the swelling rate and reducing the phase separation temperature difference of the high and low melt index polyolefin materials. The average particle diameter of the low melt index polyolefin material is preferably 10um or more from the viewpoint of improving dispersibility, reducing powder agglomeration and water absorption, and preferably 70um or less from the viewpoint of improving matching with a high melt index swelling rate and melt uniformity.
The research of the application finds that the disentanglement rate of polyolefin powder molecular chains is mainly determined by the molecular weight and the powder particle size. The larger the polyolefin molecular weight, the higher the degree of entanglement of the molecular chains, and the larger the particle diameter of the polyolefin powder, the more unfavorable the disentanglement thereof. The melting process is carried out at high temperature, so that small molecules of mineral oil can fully migrate into polyolefin molecular chains, the opening time of the molecular chains is shortened, and the processing efficiency is improved. In addition, the problem of inconsistent swelling rate of the high/low molecular weight polyolefin materials is solved by adopting the design of the high molecular weight polyolefin materials with small particle size and the low molecular weight polyolefin materials with large particle size, so that the polyolefin powder fully opens molecular chain entanglement in the high-temperature melting and blending process of an extruder, the melt non-uniformity is improved, the number of crystal points is reduced, and the defect of bright spots generated by unmelted high molecular weight polyolefin is solved.
High and low molecular weight polyolefin powder
The polyolefin powder in the present application preferably contains 10 to 30wt%, more preferably 12 to 25wt%, still more preferably 15 to 22wt% of the polyolefin powder having a particle diameter of 110 μm or more, based on 100wt% of the polyolefin powder mass fraction. The polyolefin powder having a particle size of 70 μm or less is contained in an amount of preferably 70 to 90wt%, more preferably 75 to 88wt%, still more preferably 78 to 85wt%. By controlling the ratio of polyolefin powders of different particle diameters within the above range, a melt having a uniform swelling can be obtained.
From the viewpoint of improving the melt strength, preventing creep of the extrusion molding material, and improving the tensile modulus of the separator substrate, the polyolefin powder preferably contains a polyolefin powder having a particle diameter of 110um or more in an amount of 30wt% or less, while suppressing the polyolefin powder having a particle diameter of 110um or more from rapidly swelling and coating a portion having a particle diameter of 70um or less during melt blending of the polyolefin powder with mineral oil, and reducing melt uniformity. The purpose is to obtain the gel sheet with uniform crystal nucleus growth and uniform refraction degree under the macro scale in the extrusion casting process. The polyolefin powder preferably has a polyolefin powder content of not less than 90wt% in terms of improving the high-temperature plasticizing uniformity of the polyolefin powder with mineral oil, and the conventional high-molecular weight polyolefin powder is less likely to cause solid unmelted matter due to the high entanglement of the molecular chains thereof, and is likely to cause crystallization points in the melt due to the difficulty in opening the molecular chains in the high-temperature melting stage under the mineral oil plasticizing condition, and thus causes stress concentration in terms of processing strength.
Bulk density of
In the embodiment of the present application, the bulk density of the polyolefin powder having a particle diameter of 110 μm or more is preferably 0.15 to 0.4g/cm 3 More preferably 0.2 to 0.35g/cm 3 More preferably 0.22 to 0.32g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The bulk density of the powder having a particle diameter of 70um or less is preferably 0.5 to 0.8g/cm 3 More preferably 0.55 to 0.75g/cm 3 More preferably 0.6 to 0.7g/cm 3 。
The bulk density of the polyolefin powder at a portion having a particle diameter of 110 μm or more is preferably controlled to be 0.4g/cm 3 The gaps can be fully embedded in the parts with smaller particle sizes to a certain extent, the gaps are fully dispersed in mineral oil, uneven mixing caused by layering is reduced, meanwhile, the specific surface area of the parts with the particle sizes of more than 110 mu m of polyolefin powder is large, the heat absorption efficiency is low, and therefore the molecular weight disentangling rate is reduced. The bulk density of the powder having a particle diameter of 70 μm or less is preferably 0.5g/cm 3 The above can promote the small molecules of mineral oil to be embedded into the molecular chains of the high molecular weight polyolefin, quicken the molecular chain unwrapping, and further reduce unmelts in the melt, which are generated by the high degree of entanglement of the molecular chains of the high molecular weight polyolefin.
Extrusion molding material
The application provides a processing and manufacturing method of polyolefin powder, which comprises the following steps:
(1) The mixture containing the plasticizer and the polyolefin powder is mixed and extruded from a screw extruder to form a gel sheet.
The polyolefin powder may be described with reference to the above, and need not be described here again.
Step (1) is described in detail below.
Step (1) may be simply referred to as an extrusion casting process. The extrusion casting step may be specifically a step of kneading, extruding, casting, and cooling a mixture containing a polyolefin powder and a plasticizer in a screw extruder to form a gel sheet.
In one possible example, the mixture may be mixed by a counter-current mixer, a twin-shaft blade mixer, a twin-pot mixer, or the like.
In one possible example, the mixture may be high temperature compounded by a single screw extruder or a twin screw extruder. To obtain a relatively good extrusion effect, a twin-screw extruder is preferred.
The temperature of the extruder is preferably 150 to 300 ℃, more preferably 160 to 260 ℃, still more preferably 170 to 230 ℃.
It is preferable that the temperature of the extruder is increased to improve the melt plasticizing efficiency (the temperature of the extruder is preferably 150℃or higher, more preferably 160℃or higher, and still more preferably 170℃or higher). The temperature of the extruder is reduced to facilitate prevention of oxidative decomposition of polyolefin (the temperature of the extruder is preferably 300℃or less, more preferably 260℃or less, and still more preferably 230℃or less).
The invention provides a die head of a double-screw extruder, which can accurately adjust extrusion gaps.
In order to achieve the above purpose, the following technical scheme is provided:
firstly, a die head of a double-screw extruder is provided, the die head comprises a fixed seat, a first die head and a second die head which are oppositely arranged, an extrusion channel is arranged between the first die head and the second die head, and an extrusion gap is formed between discharge ends of the first die head and the second die head by the extrusion channel;
the fixed seat and the discharge end of the first die head are correspondingly provided with a limit seat, a first wedge block is arranged between the limit seat and the first die head, the first wedge block is in single-degree-of-freedom sliding fit with the limit seat, and the sliding direction of the first wedge block relative to the limit seat is parallel to the extrusion discharge direction;
a die head adjusting inclined plane and a first wedge block inclined plane which are matched with each other are respectively arranged between the discharge end of the first die head and the first wedge block, and the thickness of the discharge end of the first die head is gradually increased along the extrusion discharge direction by the die head adjusting inclined plane;
the first wedge driving mechanism is used for driving the first wedge to slide relative to the limiting seat.
Further, a thickness reducing groove is formed in the side face, facing the first wedge block, of the discharging end of the first die head.
Further, a first sliding rail is arranged on the limiting seat, and the first wedge block is in sliding fit with the first sliding rail.
Further, the first wedge driving mechanism comprises a second wedge arranged between the first wedge and the first die head, the second wedge is in single-degree-of-freedom sliding fit with the first die head, and the sliding direction of the second wedge relative to the first die head is perpendicular to the extrusion discharging direction and the sliding direction of the first wedge relative to the limiting seat;
a second wedge inclined plane and a third wedge inclined plane which are matched with each other are respectively arranged between the first wedge and the second wedge, and the thickness of the second wedge is gradually reduced along the direction facing the second die head by the third wedge inclined plane;
and a second wedge drive mechanism for driving the second wedge to slide relative to the first die.
Further, a second sliding rail is arranged on the first die head, and the second wedge block is in sliding fit with the second sliding rail.
Further, the second wedge driving mechanism comprises a threaded hole arranged in the second wedge, a screw rod matched with the threaded hole and a power mechanism for driving the screw rod to rotate.
Further, a plurality of threaded holes are formed in the second wedge block at intervals along the width direction of the extrusion channel, and each threaded hole is internally provided with a screw rod in threaded fit with the threaded hole.
Further, the power mechanism comprises a worm and a power motor for driving the worm to rotate, a worm wheel synchronously rotating with the worm is arranged on the screw, and the worm is meshed with the worm wheel.
The method of forming the cast sheet may be, for example, a calendaring method, a free-form sheet method, or the like.
The thickness of the gel sheet is preferably 200 to 700um, more preferably 250 to 550um.
The thickness of the gel sheet is increased to facilitate the increase in mechanical strength of the separator base material (the gel sheet thickness is preferably 200um or more, more preferably 250um or more). Reducing the thickness of the gel sheet is advantageous in increasing the elongation characteristics of the separator substrate (the gel sheet thickness is preferably 700um or less, more preferably 550um or less).
The high temperature melt casting cooling method may be, for example, a direct contact cooling method such as air cooling, water cooling, oil cooling, contacting the cast sheet with a cooling roll, or the like. From the standpoint of controlling the thickness of the gel sheet and improving the uniformity of the separator substrate, the embodiments of the present application preferably employ a method of cooling by contact with a cooling roller.
The purpose of adding plasticizers to polyolefin compositions is to promote the plasticity of the polyolefin material. The plasticizer may include, for example, at least one of the following: hydrocarbon organic solvents (e.g., paraffin, etc.), 2-ethylhexyl phthalate, dibutyl phthalate, alkyl sulfonates, butyl benzyl phthalate, diisononyl phthalate. Liquid paraffin is preferred in the examples of the present application.
Alternatively, the plasticizer may be miscible with the polyolefin material (i.e., an organic solvent forming a homogeneous phase) at any ratio under high temperature conditions.
The polyolefin content in the mixture is preferably 10 to 50wt%, more preferably 12 to 30wt%, even more preferably 15 to 25wt%.
It is noted that increasing the polyolefin content in the mixture is advantageous in improving the moldability and processability of the mixture (the polyolefin content in the mixture may be, for example, 15wt% or more). Reducing the polyolefin's ratio in the mixture is beneficial to improving the pore forming properties of the mixture (the polyolefin's ratio in the mixture may be, for example, 95wt% or less).
The plasticizer is preferably present in the mixture in an amount of 50 to 90wt%, more preferably 75 to 85wt%. The addition of a plasticizer to the mixture is advantageous in providing a relatively complete pore structure in addition to improving the plasticizing ability of the polyolefin.
Optionally, the mixture further comprises inorganic particles. The inorganic particle may be a pore former.
If inorganic particles are used in step (1) and at least part of the inorganic particles are removed in the final product, it is advantageous to obtain a relatively high porosity, thereby improving the ion transport efficiency. The manner of removing the inorganic particles may be, for example, to use a liquid in which the inorganic particles are soluble.
If inorganic particles are used in step (1) and at least part of the inorganic particles remain in the final finished product, it is advantageous to increase the stability (e.g. to increase the mechanical properties, heat resistance, etc. of the film material) and polarity (i.e. to increase the affinity of the film material for the electrolyte) of the polyolefin film material.
The inorganic particles may include, for example, at least one of the following: aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, zinc oxide, barium oxide, magnesium oxide, beryllium oxide, calcium oxide, thorium oxide, aluminum nitride, titanium nitride, boehmite, apatite, aluminum hydroxide, magnesium hydroxide, barium sulfate, boron nitride, silicon carbide, silicon nitride, cubic boron nitride, hexagonal boron nitride.
The size of the inorganic particles may affect the uniformity of mixing. The particle diameter of the inorganic particles is preferably in the range of 5 to 300nm, more preferably in the range of 10 to 100nm, and even more preferably in the range of 20 to 50 nm.
Optionally, the mixture may further comprise an antioxidant.
In order to reduce oxidative decomposition of the polyolefin, an antioxidant may be added to the polyolefin composition. That is, a mixture containing polyolefin and antioxidant is kneaded and extruded in a screw extruder.
In one possible example, the antioxidant is preferably present in the mixture at a ratio of 0.1 to 5wt%, more preferably 0.2 to 2wt%.
(2) The gel sheet was biaxially stretched.
Step (2) may be simply referred to as a stretching process. The stretching step may be a step of stretching the gel sheet in the biaxial directions.
The biaxial stretching method may be, for example, asynchronous stretching (sequential biaxial stretching using a differential speed roller stretching machine in combination with a rail chain tenter, that is, stretching in the first axial direction first and then stretching in the second axial direction), synchronous stretching (simultaneous stretching using a biaxial tenter, that is, stretching in both the first axial direction and the second axial direction). Asynchronous stretching is beneficial to improving the stretch forming efficiency.
It should be noted that increasing the stretching temperature in the stretching step is advantageous in preventing cold drawing due to an excessively low stretching temperature, and further, causing a relatively large stress concentration due to insufficient activation of the molecular chains (i.e., a relatively large degree of solidification) (the stretching temperature in the stretching step may be 60 ℃ or higher, for example). The stretching temperature in the stretching step is reduced, which is advantageous for improving the pore structure of the separator (the stretching temperature in the stretching step may be, for example, 110 ℃ or lower).
(3) The plasticizer in the gel sheet is removed.
Step (3) may be simply referred to as a plasticizer removal process. The plasticizer removal process may specifically remove the plasticizer in the gel sheet by an extractant. The extractant may dissolve the plasticizer (the extractant may be a good solvent for the plasticizer) but is not compatible with the polyolefin material (i.e., the extractant cannot dissolve the polyolefin material). The extractant may include, for example, at least one of the following: halogenated hydrocarbons (e.g., methylene chloride, N-hexane, cyclohexane, etc.), acetone, tetrahydrofuran, ethanol, N-methylpyrrolidone, etc. In the examples herein, the extractant is preferably methylene chloride.
The method for removing the plasticizer can be that the gel sheet is immersed in the extractant, or the extractant is sprayed on the gel sheet to extract the plasticizer, and finally the extracted gel sheet is dried.
(4) The gel sheet was heat set.
Step (4) may be simply referred to as a heat setting process. The heat setting process may be to perform low-rate stretching and retracting operation on the gel sheet at a certain temperature to release stress accumulated in the precursor process of the gel sheet, thereby being beneficial to improving the heat stability of the gel sheet.
The reduction of the stretching temperature in the heat setting step is advantageous in reducing the crystallinity of the gel sheet (the stretching temperature in the heat setting step is preferably 135 ℃ or less). The stretching temperature in the heat-setting step is preferably increased to prevent stress concentration and microcracking in the gel sheet (the stretching temperature in the heat-setting step is preferably 105 ℃ or higher).
The retraction operation may specifically refer to relaxing or semi-free state of the gel sheet by retracting the track to relax the gel sheet.
Reducing the retraction ratio of the retraction operation is advantageous in preventing excessive relaxation, thereby facilitating an increase in the pores of the gel sheet, and facilitating an improvement in ion transport efficiency (the retraction ratio of the retraction operation is preferably 10% or less, more preferably 4.5% or less, still more preferably 3% or less).
The improvement of the retraction ratio of the retraction operation is advantageous in reducing the internal stress of the gel sheet and improving the thermal shrinkage of the gel sheet (thermal shrinkage may refer to a shrinkage phenomenon occurring under the action of the stress of the separator at high temperature) (the retraction ratio of the retraction operation is preferably 0.5% or more, more preferably 1% or more).
(5) And (5) winding and cutting.
And (5) specifically, rolling and slitting the gel sheet. Through the step (5), the membrane substrate or the membrane provided in the embodiments of the present application can be obtained.
The embodiment of the present application may not limit the execution order and the execution times of the steps (1) to (5).
For example, the execution sequence of steps (1) to (5) may be preferably: (1) - (2) - (3) - (4) - (5). And the step (2) is executed before the step (3), so that the pore structure of the diaphragm is improved, and the mechanical strength of the diaphragm is improved.
As another example, the execution sequence of steps (1) to (5) may be: (1) - (3) - (2) - (4) - (5).
As another example, the execution sequence of steps (1) to (5) may be: (1) - (3) - (2) - (3) - (4) - (5).
The step (2) (i.e., the stretching step) may be performed before or after the step (3) (i.e., the plasticizer removing step), or simultaneously with the step before the step (3), or simultaneously with the step after the step (3).
The embodiment of the application also provides a manufacturing method of the lithium ion battery. The principle is that the separator is arranged between the positive electrode material and the negative electrode material (for example, the separator is assembled in the order of positive electrode material-separator-negative electrode material or negative electrode material-separator-positive electrode material); winding a layered member containing a positive electrode material, a separator, and a negative electrode material to obtain a wound body; loading the wound body into a battery case; and (5) injecting electrolyte.
As described above, the separator provided herein may be suitable for use in a battery (e.g., a flexible battery) as a separator for the battery. In addition, the film materials provided herein may also be suitable for use in capacitors. In addition, the membrane material provided by the application can be used as a permeable membrane, a filtering membrane or an ultrafiltration membrane and the like.
In one possible example, the positive electrode material may be obtained by: mixing a positive electrode active material (such as lithium cobaltate), a conductive agent (such as conductive carbon black, super-P, SP) and a binder (such as polyvinylidene fluoride, polyvinylidene fluoride, PVDF) in a mass ratio of 97:1.5:1.5 in a solvent (such as N-methylpyrrolidone, N-methyl pyrrolidone, NMP) to form a positive electrode slurry; uniformly coating the positive electrode slurry on two sides of a plate (such as aluminum foil) through coating equipment; drying the positive electrode slurry on the plate through an oven to remove the solvent; and cold pressing, slitting and tab welding are carried out on the positive electrode material on the plate.
In one possible example, the anode material may be obtained by: mixing a negative electrode active material (such as artificial graphite), a thickening agent (such as carboxymethyl cellulose, carboxymethyl cellulose, CMC) and a binder (such as styrene butadiene rubber, styrene butadiene rubber, SBR) in a mass ratio of 97:1.3:1.7 in a solvent (such as deionized water) to form a negative electrode slurry; uniformly coating the negative electrode slurry on two sides of a plate (such as copper foil) through coating equipment; drying the negative electrode slurry on the plate through an oven to remove the solvent; and cold pressing, slitting and tab welding are carried out on the negative electrode material on the plate.
In one possible example, the diaphragm may be obtained by: and coating a membrane coating on the surface of the membrane substrate. In embodiments of the present application, the thickness of the separator coating may be, for example, 0.5 μm to 10 μm.
For example, the separator coating may include an inorganic coating (e.g., a ceramic coating) and an organic coating (e.g., an oily PVDF coating) disposed over the inorganic coating. Among them, the ceramic coating is advantageous in that the heat resistance of the separator can be improved. The PVDF coating has certain bonding performance, and can improve the bonding force between the diaphragm and the positive electrode material (or between the diaphragm and the negative electrode material), so that the diaphragm can be bonded with the positive electrode material or the negative electrode material more tightly, the hardness of the battery cell is further improved, and the passing rate of the needling test of the battery cell is improved. If a bonding gap exists between the separator and the positive electrode material or the negative electrode material, the hardness of the battery cell is not facilitated, and the passing rate of the needling test of the battery cell is also not facilitated.
As another example, the separator coating may include only an organic coating or an organic/inorganic hybrid coating, i.e., may be directly coated on the surface of the separator substrate.
The positive electrode material, the separator and the negative electrode material are wound together to form a bare cell. The power storage capacity of the bare cell can reach 3.8Ah, and the working voltage of the bare cell can be 3.0-4.43V.
And (3) packaging, baking, injecting liquid, forming and the like are carried out on the bare cell, so that a lithium ion battery finished product can be manufactured.
Examples provided herein are set forth in detail below by way of examples 1-12.
Example 1
The polyolefin extrusion provided in example 1 may include a separator substrate, and the separator substrate may include a polyolefin powder and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.75, and when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 230. Mu.m, a partial melt index (190 ℃/21.6 kg) of 15g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.2g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator provided in example 1 can be obtained by the steps (1) to (5) described above.
Specifically, the specific content of the step (1) includes: premixing the polyolefin powder and the antioxidant by using a double-shaft blade mixer to obtain a premix; nitrogen is introduced into the feeder and the twin-screw extruder in advance, and then the premix is fed into the twin-screw extruder through the feeder; preheating liquid paraffin by oil pump (the preheating temperature of liquid paraffin is 40deg.C, wherein the viscosity of liquid paraffin at 40deg.C can be 28-35 centistokes, wherein centistokes is a kinematic viscosity unit, which can be abbreviated as cst,1 cst=1 mm) 2 S) feeding the mixture into a double-screw extruder, wherein the extrusion amount is controlled to be 75-100 kg/h; the temperature of the melt-kneading may be 170℃and the screw speed may be 28r/min (revolutions per minute, revolutions per minute, rpm); the amount of the oil feed pump was adjusted so that the solid content of the polyolefin during kneading was set to a set value (the solid content of the polyolefin can be referred to table 1 below). Finally obtaining a blend; the blend was extruded through a twin screw extrusion die and cast cooled to obtain a gel sheet (the thickness of the gel sheet can be referred to table 1 below), the gel sheet thickness being controlled to 300 to 450 μm。
Specifically, the specific content of the step (2) includes: the gel sheet was set in an asynchronous stretcher for biaxial stretching (specific parameters of biaxial stretching can be referred to table 1 below).
Specifically, the specific content of the step (3) includes: the stretched gel sheet was extracted with methylene chloride to remove the liquid paraffin in step (1).
Specifically, the specific content of the step (4) includes: the gel sheet after extraction was heat-set (specific parameters for heat-setting can be referred to in table 1 below).
Specifically, the specific content of the step (5) includes: and continuously slitting and rolling the gel sheet after heat setting.
Other specific parameters of example 1 can be found in table 1 below.
Example 2
The separator provided in example 2 may include a separator substrate. The initial crystallization temperature of the polyolefin powder was 117.6℃and Mv1/Mv was 0.85, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 74.9% by weight, a partial melt index (190 ℃/21.6 kg) of the polyolefin powder having a particle size of 230. Mu.m, 14.9g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.22g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator provided in embodiment 2 may be prepared by steps (1) to (5) described above, and specific details may be referred to embodiment 1 above, and detailed descriptions thereof are not necessary here.
Other specific parameters of example 2 can be found in table 1 below.
Example 3
The separator provided in example 3 may include a separator substrate. The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.95, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 230. Mu.m, a partial melt index (190 ℃/21.6 kg) of 15g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.2g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator coating may include a heat resistant coating and a bond coating. The heat-resistant coating may include Al 2 O 3 . The bond coat may include oily PVDF.
The manufacturing method and other specific parameters of the separator provided in embodiment 3 can be referred to in embodiment 2 and table 1, and need not be described in detail herein.
Example 4
The separator provided in example 4 may include a separator substrate. The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.85, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 150um in an amount of 25% by weight, a polyolefin powder having a particle size of 65um in an amount of 75% by weight, a partial melt index (190 ℃/21.6 kg) of the polyolefin powder having a particle size of 150um in an amount of 15g/10min, a polyolefin powder having a particle size of 65um in an amount of 190 ℃/21.6kg in an amount of 0.3g/10min, and a bulk density of the polyolefin powder in a portion of 150um in an amount of 0.37g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises 3- (3, 5-di-tert-butyl)Isooctyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The manufacturing method and other specific parameters of the separator provided in embodiment 4 can be referred to in embodiment 2 and table 1, and need not be described in detail herein.
Example 5
The separator provided in example 5 may include a separator substrate. The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.85, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained 15% by weight of the polyolefin powder having a particle size of 230. Mu.m, 85% by weight of the polyolefin powder having a particle size of 65. Mu.m, a partial melt index (190 ℃/21.6 kg) of the polyolefin powder having a particle size of 230. Mu.m was 15g/10min, a melt index (190 ℃/21.6 kg) of the polyolefin powder having a particle size of 65. Mu.m was 0.3g/10min, and the bulk density of the polyolefin powder having a particle size of 230. Mu.m was 0.22g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The manufacturing method and other specific parameters of the separator provided in embodiment 5 can be referred to in embodiment 2 and table 1, and need not be described in detail herein.
Example 6
The separator provided in example 6 may include a separator substrate. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.85, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 230. Mu.m, a partial melt index (190 ℃/21.6 kg) of 20g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.22g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . Polyolefin groupThe compound may not include its interpolymer and its derivatives. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The manufacturing method and other specific parameters of the separator provided in example 6 can be referred to in example 2 and table 1, and detailed description thereof is not necessary here.
Table 1 specific parameters of examples 1-6
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Example 7
The separator provided in example 7 may include a separator substrate and a separator coating.
The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.85, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 74.9% by weight, a partial melt index (190 ℃/21.6 kg) of the polyolefin powder having a particle size of 230. Mu.m, 14.9g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.22g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator coating may include a heat resistant coating and a bond coating. The heat resistant coating may include boehmite. The bond coat may include aqueous PVDF.
The manufacturing method and other specific parameters of the separator provided in embodiment 7 can be referred to in embodiment 2 and table 2, and need not be described in detail herein.
Example 8
The separator provided in example 8 may include a separator substrate and a separator coating.
The separator substrate may include a polyolefin composition and an antioxidant. The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.95, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 230. Mu.m, a partial melt index (190 ℃/21.6 kg) of 15g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.2g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator coating may include a heat resistant coating and a bond coating. The heat resistant coating may include boehmite. The bond coat may include an aqueous PVDF.
The manufacturing method and other specific parameters of the separator provided in example 8 can be referred to in example 3 and table 2, and detailed description thereof is not necessary.
Example 9
The separator provided in example 9 may include a separator substrate and a separator coating.
The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder is 117.5 ℃, the Mv1/Mv is 0.85, when the mass fraction of the polyolefin powder is 100wt%, the polyolefin powder contains the polyolefin powder with the particle size of 230um with the content of 25.1wt%, the polyolefin powder with the particle size of 65um with the content of 74.9wt%, the partial melt index (190 ℃/21.6 kg) of the polyolefin powder with the particle size of 230um with the melting index of 14.9g/10min, and the melting index of the polyolefin powder with the particle size of 65umThe number (190 ℃ C./21.6 kg) was 0.3g/10min, and the bulk density of the polyolefin powder at 230 μm fraction was 0.22g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator coating may include a heat resistant coating and a bond coating. The heat resistant coating may include boehmite and Al 2 O 3 . The bond coat may include oily PVDF.
The manufacturing method and other specific parameters of the separator provided in example 9 can be referred to in example 2 and table 2, and detailed description thereof is not necessary here. The specific processing parameters of example 9 may be different from those of example 2 (for example, including extrusion amount, gel sheet thickness, and stretching ratio of biaxial stretching).
Examples 10 to 12
The separator provided in examples 10-12 may include a separator substrate and a separator coating.
The separator substrate may include a polyolefin composition and an antioxidant. The separator substrate may include a polyolefin composition and an antioxidant. The initial crystallization temperature of the polyolefin powder was 117.5℃and Mv1/Mv was 0.95, when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle size of 230. Mu.m, a polyolefin powder having a particle size of 65. Mu.m, a polyolefin powder having a particle size of 230. Mu.m, a partial melt index (190 ℃/21.6 kg) of 15g/10min, a polyolefin powder having a particle size of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of the polyolefin powder having a particle size of 230. Mu.m, a bulk density of 0.2g/cm 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator coating may include a heat resistant coating and a tackyAnd (5) a coating layer. The heat resistant coating may include boehmite and Al 2 O 3 . The bond coat may include oily PVDF.
The manufacturing methods and other specific parameters of the separators provided in examples 10 to 12 can be referred to in example 3 and table 2, and detailed descriptions thereof are not necessary here. The specific processing parameters of examples 10 to 12 may be different from those of example 2 (for example, the extrusion amount, the gel sheet thickness, the stretching ratio of biaxial stretching, and the like are included).
TABLE 2 specific parameters for examples 7-12
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The 6.5 μm polyolefin film materials of examples 1-6 showed excellent performance in terms of mechanical properties, closed cell/rupture temperature, and the like, as measured conventionally. As can be seen from example 1, the yellowing resistance Mv1/Mv of the polyolefin powder significantly affects the film forming quality of the polyolefin material during extrusion processing, and when Mv1/Mv is 0.75, it is shown that the polyolefin powder has insufficient oxidation resistance and is easy to undergo oxidative decomposition to form carbonized solid matters, and bright spots containing unmelted matters are shown on the film surface, and the number of the bright spots reaches 5/500 m 2 The size of the bright spots reaches a serious defect with the length of 10um and the width of 7 um. And the test of the performance of the battery cell cannot be successfully passed. Examples 2 to 6 show that the bright spot defect of the polyolefin film material can be improved by properly controlling the yellowing resistance Mv1/Mv and adjusting the particle size distribution of the polyolefin powder, the components of the polyolefin with high viscosity average molecular weight are improved, the swelling rate of the powder is optimized, the number and the size of bright spots are reduced, and the safety of the film material is further improved; however, when the yellowing resistance Mv1/Mv is further improved (more than or equal to 0.95), the problem of uneven plasticization may occur, and the high-melt-index portion is generated to melt and cover the unmelted low-melt-index portion, so that bright spots are formed, and the closed pore temperature of the diaphragm may also be increased. This means that forThe anti-yellowing ability Mv1/Mv and the particle size distribution of the polyolefin powder are relatively important for the homogeneity of the melt in terms of the overall properties of the film material.
It can be seen from examples 7-12 that the coating process (such as adjusting the conditions of coating materials, systems, etc.) of the diaphragm can reduce the safety influence of bright spots on the film materials, improve the cell performance index of the diaphragm, and improve the performance consistency of the diaphragm.
Through combining a plurality of polyolefin according to a specific mode and adopting a traditional wet diaphragm manufacturing process, and through controlling the yellowing resistance Mv1/Mv and the powder particle size distribution, the blending synergistic effect of a plurality of polyolefin materials is realized, the non-uniformity phenomenon of polyolefin powder in a high-temperature melting state can be improved, and the generation number and size of bright spots can be reduced.
Comparative examples 1 to 6
The separator provided in comparative examples 1 to 6 may include a separator substrate and a separator coating layer.
The separator substrate may include a polyolefin composition and an antioxidant. The separator substrate may include a polyolefin composition and an antioxidant. The polyolefin powder of comparative examples 1 to 2 had an initial crystallization temperature of 105.5℃and a Mv1/Mv of 0.85, and when the mass fraction of the polyolefin powder was 100% by weight, the polyolefin powder contained a polyolefin powder having a particle diameter of 230. Mu.m, a polyolefin powder having a particle diameter of 65. Mu.m, a partial melt index (190 ℃/21.6 kg) of 230. Mu.m, 15g/10min, a polyolefin powder having a particle diameter of 65. Mu.m, a melt index (190 ℃/21.6 kg) of 0.3g/10min, and a bulk density of 0.2g/cm of the polyolefin powder having a particle diameter of 230. Mu.m 3 The bulk density of the polyolefin powder having a particle size of 65 μm was 0.6g/cm 3 . The polyolefin composition may not include its interpolymer and its derivative. The antioxidant comprises isooctyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate. The antioxidant may be present in the separator substrate at a ratio of 0.3wt%.
The separator coating may include a heat resistant coating and a bond coating. The heat resistant coating may include boehmite and Al 2 O 3 . The bond coat may include an aqueous PVDF.
Comparative examples 3 to 4 differ from comparative example 1 mainly in that the initial crystallization temperature was 117.5℃and Mv1/Mv was 0.60; comparative examples 5 to 6 are different from comparative example 3 mainly in that the polyolefin powder having a Mv1/Mv of 0.85 and a melt index of 15g/10min and 0.3g/10min had the same particle size (100 um).
The manufacturing method and other specific parameters of the separator provided in comparative examples 1 to 6 can be referred to example 3, and detailed description thereof is not necessary.
Table 3 specific parameters of comparative examples 1 to 6
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The 6.5 μm polyolefin film materials of comparative examples 1-6 showed excellent performance in terms of indexes such as mechanical properties, closed cell/rupture temperature, etc. As can be seen from comparative example 1, the initial crystallization temperature of the polyolefin powder significantly affects the melt phase separation consistency of the polyolefin material in the casting stage, and when the initial crystallization temperature of the polyolefin is 105 ℃, a large amount of non-impurity bright spots appear, and simultaneously the thermal stability is poor, and the number of the bright spots reaches 50/500 m 2 The size of the bright spots reaches the serious defect of 13.7um in length and 6.8um in width, and cannot pass the cell performance test. The comparative examples 3 to 6 show that the yellowing resistance Mv1/Mv and the particle size distribution of different melt indexes significantly affect the type of bright spots of the diaphragm, and polyolefin Mv1/Mv below 0.75 is easy to produce carbonized impurity bright spots, and the particle size distribution is not optimized (the particle sizes of polyolefin with different melt indexes are consistent) is easy to produce bright spots caused by unmelted matters.
The embodiment of the application also provides a test method of the specific parameters.
4.1 viscosity average molecular weight and molecular weight distribution
a. Sampling: the polyolefin material is completely dissolved in organic solvents such as decalin, tetrahydrofuran and the like to prepare a solution with the concentration of 0.5-1.5 mg/mL, and the solution is stood for a period of time at room temperature and can not be sonicated, and is filtered by a semipermeable membrane.
b. And (3) testing: the viscosity of the polyolefin material was measured by Gel Permeation Chromatography (GPC) at 135℃and was determined according to the following calculation formula]Calculation of the viscosity average molecular weight M v ：
[η]＝6.77×10 -4 M v 0.67
Wherein the viscosity average molecular weight of polypropylene can be calculated according to the following formula:
[η]＝1.10×10 -4 M v 0.8
c. and (3) data processing: the molecular weight distribution can be read by plotting the viscosity versus viscosity average molecular weight distribution.
Alternatively, multiple tests can be performed on the polyolefin material and an arithmetic mean calculated (calculation of the arithmetic mean is advantageous in reducing the variation introduced by the measurement system).
4.2 film thickness
Mode one:
a. sampling:
1X 10 cut from the diaphragm 3 mm 2 Samples (the area of the sample may also be ≡1.5X10, for example) 3 mm 2 ) The number of test points is dependent on the diaphragm (typically not less than 10 points).
b. And (3) testing: the test was carried out by means of a thickness-per-million measuring instrument at 23.+ -. 2 ℃.
c. And (3) data processing: and taking an actual measurement value of the thickness of each test point and taking an arithmetic average value.
Mode two:
a. sampling:
for products with a width < 200 mm: determining a point at intervals of 40mm plus or minus 5mm along the longitudinal (MD) direction, wherein the number of test points is not less than 10, the number of test points can be determined according to the width of the diaphragm, and the distance between a measurement start point and an edge is not less than 20mm;
for products with a width of more than or equal to 200 mm: and determining a point every 80mm plus or minus 5mm along the Transverse Direction (TD), wherein the number of test points is not less than 10, the number of test points can be determined according to the width of the diaphragm, and the distance between the measurement start point and the edge is not less than 20mm.
b. And (3) testing: each test point is tested by a thickness measuring instrument at the temperature of 23+/-2 ℃, the diameter of the measuring surface is between 2.5 and 10mm, and the load applied to the test sample by the measuring surface is between 0.5 and 1.0N.
c. And (3) data processing: and taking an actual measurement value of the thickness of each test point and taking an arithmetic average value.
4.3 porosity (%)
Mode one:
a. sampling: 1X 10 cut from the diaphragm 4 mm 2 And (3) a sample.
b. And (3) testing: the porosity was measured using a density method.
c. And (3) data processing:
the porosity P of the whole sample can be calculated by the following formula:
true density, V, can be the volume of the sample.
Mode two:
a. Sampling: rectangular samples were taken 1 by a 237X 170mm template sampler. When sample is cut, the edge of the diaphragm (for example, the edge is more than 50mm away from the edge of the diaphragm) is kept away as far as possible.
b. And (3) testing: the porosity is measured using a density method, which includes measuring n (n may be greater than or equal to 9, for example) points of the sample, which n points may be distributed in an equidistant lattice.
c. And (3) data processing: porosity P of each point i The method can be calculated by the following formula:
wherein m is i For the mass of each point, ρ is the skeleton density of the sample (which can be calculated according to the material proportion), V i The total volume of each point (which can be calculated according to the length, width and thickness of the sample);
the porosity P of the whole sample can be calculated by the following formula:
4.4, air permeability (s/100 cc)
Mode one:
a. sampling: samples with diameters of more than or equal to 28mm are taken from the diaphragm.
b. And (3) testing: the test was conducted according to the method specified in JIS P8117-2009. Specifically, the method comprises the following steps: the cylinder-driven pressure reducing valve was set to a pressure of 0.25MPa, the test pressure was set to 0.05MPa, and the test standard was selected as "JIS".
c. And (3) data processing: 6 samples are randomly cut out in the full width of the diaphragm, the air resistance of each sample is recorded, and the arithmetic average value of each sample is calculated.
Mode two:
a. sampling: 6 samples were taken from the shape by a 100X 100mm template sampler. When sample is cut, the edge of the diaphragm (for example, the edge is more than 50mm away from the edge of the diaphragm) is kept away as far as possible. Each sample was uniformly distributed on the membrane (i.e., dividing the full width of the membrane into 6 zones, and 1 sample was cut in each of these 6 zones).
b. And (3) testing: the test was conducted according to the method specified in JIS P8117-2009. Specifically, the method comprises the following steps: the cylinder-driven pressure reducing valve was set to a pressure of 0.25MPa, the test pressure was set to 0.05MPa, and the test standard was selected as "JIS".
c. And (3) data processing: the magnitude of the air resistance of each sample was recorded separately, and the arithmetic average of the air resistances of the 6 samples was calculated.
4.5 puncture Strength
Mode one:
a. sampling: samples with diameters of more than or equal to 45mm are taken from the microporous membrane.
b. And (3) testing: the sample is fixed on the clamp in the middle, the test needle is spherical (made of ruby) with the diameter of 1mm, the sample is ensured to extend to or exceed the edge of the clamping disc in all directions, and the sample is ensured to be completely fixed on the annular clamp without slipping. During the test, the diaphragm was pierced, the speed of the machine was set at 300.+ -.10 mm/min, until the piercing ball bat completely ruptured the sample, and the piercing resistance was the maximum force recorded during the test.
c. And (3) data processing: 6 samples are randomly cut out in full width, puncture intensity values of the samples are recorded, and an arithmetic average value of the puncture intensity values of the samples is calculated.
Mode two:
a. sampling: rectangular samples were taken 6 by a 237X 170mm template sampler. When sample is cut, the edge of the diaphragm (for example, the edge is more than 50mm away from the edge of the diaphragm) is kept away as far as possible. Each sample was uniformly distributed on the membrane (i.e., dividing the full width of the membrane into 6 zones, and 1 sample was cut in each of these 6 zones).
b. And (3) testing: the test was carried out according to the method prescribed in standard astm d 4833-07. Specifically, the method comprises the following steps: the test needle is a spherical needle with the diameter of 1mm (ruby); the sample is fixed on the clamp in a centering way, so that the sample is ensured to extend to or exceed the edge of the clamping disc in all directions, and the sample is ensured to be completely fixed on the annular clamp without slipping; during testing, the speed of the machine is set to 300+/-10 mm/min, and the diaphragm is punctured until the test needle head completely breaks the sample; puncture resistance is the maximum force recorded during the test.
c. And (3) data processing: the puncture strength of each sample was recorded separately, and the arithmetic average of the puncture strengths of the 6 samples was calculated.
4.6 tensile Strength and elongation
Mode one:
a. sampling: on the whole breadth sample, cutting the diaphragm according to MD and TD directions to obtain a plurality of long strip-shaped samples with the length of more than or equal to 50mm and the width of about 15+/-0.1 mm (the width of the sample can be along the TD direction of the diaphragm, the length of the sample can be along the MD direction of the diaphragm when tested by MD, the width of the sample can be along the MD direction of the diaphragm, and the length of the sample can be along the TD direction of the diaphragm when tested by TD).
b. And (3) testing: and stretching by using a stretcher, wherein the interval between the clamps can be 100+/-5 mm until the sample is broken, and the stretching speed can be 100+/-1 mm/min.
c. And (3) data processing: the tensile strength, elongation were recorded separately for each sample.
Mode two:
a. sampling: rectangular samples were taken 6 by a 237X 170mm template sampler. When sample is cut, the edge of the diaphragm (for example, the edge is more than 50mm away from the edge of the diaphragm) is kept away as far as possible. Each sample was uniformly distributed on the separator (i.e., the full width of the separator was equally divided in the MD and TD directions of the separator, resulting in 6 zones, and 1 sample was cut in each of these 6 zones). Then, a strip sample with the length of more than or equal to 150mm and the width of 15+/-0.1 mm is cut by a sampling instrument.
b. And (3) testing: the measurement was carried out according to the method specified in GB/T1040.3-2006. Specifically, the method comprises the following steps: the clamp spacing may be 100+ -5 mm and the stretching speed may be 100+ -1 mm/min.
c. And (3) data processing: the tensile strength, elongation, and arithmetic mean of these 6 samples were recorded separately for each sample.
4.7 tensile modulus
Mode one:
a. sampling: on the whole breadth sample, cutting the diaphragm according to MD and TD directions to obtain a plurality of long strip-shaped samples with the length of more than or equal to 50mm and the width of about 15+/-0.1 mm (the width of the sample can be along the TD direction of the diaphragm, the length of the sample can be along the MD direction of the diaphragm when tested by MD, the width of the sample can be along the MD direction of the diaphragm, and the length of the sample can be along the TD direction of the diaphragm when tested by TD).
b. And (3) testing: stretching is carried out by a stretcher, the clamp spacing can be 100+/-5 mm, the stretching speed can be 25+/-1 mm/min, the starting point strain can be set to 0.05%, and the ending point strain can be set to 0.5%.
c. And (3) data processing: the tensile modulus can be calculated by a regression slope method, and the value of the tensile modulus can be equal to the slope of a least squares regression linear fit of the stress-strain curve in Mpa (refer to GB/T1040.1-2018) in the interval of 0.05% -0.25% strain.
Mode two:
a. sampling: rectangular samples were taken 6 by a 237X 170mm template sampler. When sample is cut, the edge of the diaphragm (for example, the edge is more than 50mm away from the edge of the diaphragm) is kept away as far as possible. Each sample was uniformly distributed on the separator (i.e., the full width of the separator was equally divided in the MD and TD directions of the separator, resulting in 6 zones, and 1 sample was cut in each of these 6 zones). Then, a strip sample with the length of more than or equal to 150mm and the width of 15+/-0.1 mm is cut by a sampling instrument.
b. And (3) testing: stretching is carried out by a stretcher, the clamp spacing can be 100+/-5 mm, the stretching speed can be 25+/-1 mm/min, the starting point strain can be set to 0.05%, and the ending point strain can be set to 0.5%.
c. And (3) data processing: the tensile modulus can be calculated by a regression slope method, and the value of the tensile modulus can be equal to the slope of a least squares regression linear fit of the stress-strain curve in Mpa (refer to GB/T1040.1-2018) in the interval of 0.05% -0.25% strain.
4.8 pore size
a. Sampling: a round specimen having a diameter of 15mm was taken with a corresponding tool, and then the specimen was immersed in a glass dish containing a test solution with forceps.
b. And (3) testing: the test was performed using the bubble point method. Samples were placed in sample caps and tested according to standard ASTM F316-2011, procedure of pore size analyzer. Compressed air may be used at low pressure, which may be 80psi; low purity nitrogen can be used at high pressure, and the pressure is more than or equal to 350psi.
c. And (3) data processing: and according to the test result, a test report of the pore size and pore size distribution of the sample is derived.
4.10, 130 ℃ heat shrinkage
a. Sampling: 6 samples were randomly cut out across the full width. Specific sampling of each specimen may include: cutting 100mm along the MD direction of the diaphragm; when the TD direction of the separator is greater than 100mm, the length of the test sample in the TD direction may be 100mm; when the TD direction of the microporous membrane is less than 100mm, the length of the test sample in the TD direction may be practically equal.
b. And (3) testing: marking longitudinal and transverse marks of the samples, and measuring and recording the longitudinal and transverse dimensions of each sample; heating to 130 ℃ by an electric heating constant temperature box; the sample is horizontally placed in a paper jacket layer, and the sample has no folding, wrinkling, adhesion and other conditions; placing the paper sleeve (the number of layers can be 10 for example) with the sample in the middle of the constant temperature oven flatly (the door opening time is not more than 3s for example); heating the sample to 130 ℃ by an electric heating constant temperature box for 1h; after taking out the sample, the sample was cooled to room temperature, and the longitudinal length and the transverse length were measured.
c. And (3) data processing:
the heat shrinkage of each sample was calculated:
T＝(L 0 -L)/L 0 ×100％，
wherein T can be the heat shrinkage (%), L of the sample 0 The length (mm) of the sample before heating may be used, and the length (mm) of the sample after heating may be used. An arithmetic average of the heat shrinkage of the samples was calculated.
4.11, melting Point (. Degree.C.) and crystallinity (%)
a. Sampling: the diaphragm sample was weighed on a balance with an accuracy of 0.01 mg. The mass of the diaphragm sample is between 5mg and 10 mg. The mass difference between the parallel samples should be within + -2 mg.
b. And (3) testing: using a Differential Scanning Calorimeter (DSC) and measuring the concentration of the metal in N 2 Testing under atmosphere, heating to 30 ℃ above the melting point of the polyolefin at 10 ℃ per minute for the first time, preserving heat for 3min to obtain the primary heating crystallization degree of the polyolefin, then cooling to 40 ℃ or less at 10 ℃ per minute, preserving heat for 3min, heating to 30 ℃ above the melting point of the polyolefin at 10 ℃ per minute for the second time, obtaining the secondary heating crystallization degree of the polyolefin, and directly reading the melting point temperature.
c. And (3) data processing: calculating the area under the melting endotherm (i.e., integrating the melting endotherm) curve (from the start of the heating cycle to the creation of the heat transfer enthalpy), to obtain a melting enthalpy value in joules (J); dividing the melting enthalpy value by the sample mass (g) to obtain a mass normalized melting enthalpy (ΔH) of the sample s ). The crystallinity X (%) of the sample can then be calculated according to the following formula:
crystallinity X (%) =mass normalized melting enthalpy of sample (Δh) s ) 100% crystalline polyolefin melting enthalpy (DeltaH) f )×100％，
Wherein 100% of the crystalline polyolefin has a melting enthalpy (DeltaH) f )＝293.8J/g。
4.12 needling test
a. Sampling: each set takes 5 energy storage system (power conversion system, pcs) batteries and marks the central location of the cell.
b. And (3) testing: charging the cell to a limiting voltage of 4.43V at 25±3 ℃ at a constant current of 1.2A, and then charging at a Constant Voltage (CV) of 4.43V until the current decreases to 0.025C; after full charge, testing is carried out within 12-24 hours; the steel nail is penetrated into the central part of the cell at the speed of 150mm/s at the temperature of 25+/-3 ℃ until penetrating, and the needle is retracted after 10 minutes. The diameter of the steel nail is 2.45 plus or minus 0.06mm, the length is 45 plus or minus 2.5mm, and the tip length can be between 2mm and 4.9 mm.
c. And (3) data processing: and observing experimental phenomena, and judging that the needle passes through the experimental phenomena without causing fire or explosion after needling.
4.13, 130 ℃ thermal shock test
a. Sampling: 5pcs of cells were taken for each group.
b. And (3) testing: charging the cell to a limiting voltage of 4.43V at 25±3 ℃ at a constant current of 1.2A, and then charging at a Constant Voltage (CV) of 4.43V until the current decreases to 0.025C; after full charge, testing is carried out within 12-24 hours; heating the battery core from the initial temperature of 25+/-3 ℃ by a convection mode or a circulating hot air box, wherein the temperature change rate can be 5+/-2 ℃/min; heating to 130+ -2deg.C, and maintaining for 30min.
c. And (3) data processing: and observing experimental phenomena, and judging that the experimental phenomena are passed after temperature rise without causing fire or explosion.
4.14, 140 ℃ thermal shock test
a. Sampling: 5pcs of cells were taken for each group.
b. And (3) testing: charging the battery to a limiting voltage of 4.43V at 25+ -3deg.C at a constant current of 1.2A, and then charging at a Constant Voltage (CV) of 4.43V until the current decreases to 0.025C; after full charge, testing is carried out within 12-24 hours; heating the battery from the initial temperature of 25+/-3 ℃ by a convection mode or a circulating hot air box, wherein the temperature change rate can be 5+/-2 ℃/min; heating to 140+ -2deg.C, and maintaining for 30min.
c. And (3) data processing: and observing experimental phenomena, and judging that the experimental phenomena are passed after temperature rise without causing fire or explosion.
Embodiments of the present application provide a separator for a battery, which has characteristics that enable any of the above embodiments.
Embodiments of the present application provide a battery having a separator that implements the above.
The embodiment of the application also provides electronic equipment, which comprises the battery. The electronic device may be a mobile phone, a tablet, etc.
The embodiment of the application also provides a mobile device, which comprises the battery. The mobile device may be an automobile or the like.
In this application, "and/or" describes an association relationship of an association object, which means that there may be three relationships, for example, a and/or B may mean: a alone, a and B together, and B alone, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the present application, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items. The character "/" herein generally indicates that the associated object is an "or" relationship.
While the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be appreciated that various embodiments of the invention may be practiced otherwise than as specifically described, and that no limitations are intended to the scope of the invention except as may be modified or practiced in any way within the spirit and principles of the invention. The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (15)
1. A polyolefin powder, characterized in that the polyolefin powder has a viscosity average molecular weight Mv of 15X 10 4 Above 300×10 4 Wherein the initial crystallization temperature of the polyolefin powder is 108 ℃ to 120 ℃ by using a hot stage polarization microscope under the following measurement conditions,
measurement conditions of a polarizing microscope:
heating the heat table to 200 ℃ at a heating rate of 10 ℃/min, and maintaining for 3min;
the temperature of the hot table is reduced from 200 ℃ to 130 ℃ at a temperature reduction rate of-10 ℃/min;
cooling the temperature of the hot table from 130 ℃ to 120 ℃ at a cooling rate of-5 ℃/min;
cooling the temperature of the hot table from 130 ℃ to 118 ℃ at a cooling rate of-2 ℃/min;
cooling the temperature of the hot stage from 118 ℃ to 110 ℃ at a cooling rate of-0.5 ℃/min;
defining the temperature at which the polyolefin melt starts to crystallize under a polarizing microscope as an initial crystallization temperature;
the viscosity average molecular weight Mv of the polyolefin powder satisfies the following relationship with the viscosity average molecular weight Mv1 of the polyolefin obtained by oxidation under the following yellowing conditions,
Mv1/Mv≥0.75，
yellowing conditions:
the yellowing condition is anaerobic;
blending 30wt% polyolefin powder with 70wt% mineral oil;
placing the blend on a heating platform, and keeping the temperature at 40 ℃ for 0.5h;
Heating the heating platform to 150 ℃ at a heating rate of 10 ℃/min, and maintaining for 0.5h;
heating the heating platform to 200 ℃ at a heating rate of 5 ℃/min, and maintaining for 1h;
the partial melt index of the polyolefin powder with the grain diameter of more than 110um is 10-30 g/10min, and the melt index of the polyolefin powder with the grain diameter of less than 70um is less than or equal to 0.5g/10min; the test conditions of the melt index are as follows: the temperature is 190 ℃ and the load is 21.6g;
at least one selected from the group consisting of an ethylene homopolymer or a polyethylene-propylene copolymer, a derivative of a polyethylene-propylene copolymer, a polyethylene-butene copolymer, a derivative of a polyethylene-butene copolymer, a polyethylene-hexene copolymer, a derivative of a polyolefin-hexene copolymer, a polyolefin-octene copolymer, a derivative of a polyolefin-octene copolymer, a polystyrene-ethylene-styrene copolymer, a derivative of a polystyrene-ethylene-styrene copolymer, a polystyrene-ethylene-butene-styrene copolymer, a derivative of a polystyrene-ethylene-butene-styrene copolymer, a polyolefin-hydrogenated oligocyclopentadiene, a derivative of a polyolefin-hydrogenated oligocyclopentadiene, polyethylene oxide, a derivative of polyethylene oxide, a polypentene-ethylene copolymer, a derivative of a polypentene-ethylene copolymer, a polyhexene-ethylene copolymer, a derivative of a polyhexene-ethylene copolymer, a polymethylpentene-ethylene copolymer, and a derivative of polymethylpentene-ethylene copolymer;
When the mass fraction of the polyolefin powder is 100wt%, the polyolefin powder contains 10-30 wt% of polyolefin powder with the particle size of more than 110um and 70-90 wt% of polyolefin powder with the particle size of less than 70 um;
the bulk density of the polyolefin powder with the grain diameter of more than 110um is 0.15-0.6 g/cm 3 The bulk density of the polyolefin powder having a particle size of 70um or less is 0.6 to 0.9g/cm 3 ；
The ethylene monomer content in the ethylene copolymer is 3wt% or more and 20wt% or less.
2. The polyolefin powder according to claim 1, wherein the polyolefin powder, after melting, has a material density of 0.9g/cm 3 Above and 0.97g/cm 3 The following is given.
3. An extrusion molding material, characterized in that the polyolefin powder according to any one of claims 1 to 2 is processed and molded.
4. The extrusion material of claim 3 wherein the extrusion material is a microporous film.
5. The extrusion material of claim 4, wherein the microporous film is prepared by an extrusion die:
the die head of the double-screw extruder comprises a fixed seat (3), and a first die head (1) and a second die head (2) which are oppositely arranged, wherein an extrusion channel (4) is arranged between the first die head (1) and the second die head (2), and an extrusion gap (5) is formed between the discharge ends of the first die head (1) and the second die head (2) by the extrusion channel (4);
The fixed seat (3) and the discharge end of the first die head (1) are correspondingly provided with a limit seat (6), a first wedge block (7) is arranged between the limit seat (6) and the first die head (1), the first wedge block (7) is in single-degree-of-freedom sliding fit with the limit seat (6), and the sliding direction of the first wedge block (7) relative to the limit seat (6) is parallel to the extrusion discharging direction;
a die head adjusting inclined surface (8) and a first wedge block inclined surface (9) which are matched with each other are respectively arranged between the discharge end of the first die head (1) and the first wedge block (7), and the thickness of the discharge end of the first die head (1) is gradually increased along the extrusion discharge direction by the die head adjusting inclined surface (8);
the die head also comprises a first wedge block driving mechanism for driving the first wedge block (7) to slide relative to the limiting seat (6), wherein a thickness reducing groove (10) is formed in the side surface of the discharge end surface of the first die head (1) facing the first wedge block (7); the first wedge driving mechanism comprises a second wedge (11) arranged between the first wedge (7) and the first die head (1), the second wedge (11) is in single-degree-of-freedom sliding fit with the first die head (1), and the sliding direction of the second wedge (11) relative to the first die head (1) is perpendicular to the extrusion discharging direction and the sliding direction of the first wedge (7) relative to the limiting seat (6);
A second wedge inclined surface (12) and a third wedge inclined surface (13) which are matched with each other are respectively arranged between the first wedge (7) and the second wedge (11), and the thickness of the second wedge (11) is gradually reduced along the direction towards the second die head (2) by the third wedge inclined surface (13);
the second wedge driving mechanism comprises a threaded hole (14) arranged in the second wedge (11), a screw rod (15) matched with the threaded hole (14) and a power mechanism for driving the screw rod (15) to rotate;
the power mechanism comprises a worm (16) and a power motor for driving the worm (16) to rotate, a worm wheel (17) which rotates synchronously with the worm is arranged on the screw (15), and the worm (16) is meshed with the worm wheel (17).
6. A separator, characterized in that the separator is formed by processing the polyolefin powder according to any one of claims 1 to 2.
7. The diaphragm of claim 6 wherein the diaphragm has a primary temperature rise crystallinity of less than or equal to 72% and a secondary temperature rise crystallinity of less than or equal to 60% as measured using a Differential Scanning Calorimeter (DSC);
DSC measurement conditions:
(1) At N 2 Testing under atmosphere, heating to 30 ℃ above the melting point of the polyolefin at 10 ℃ per minute for the first time, preserving heat for 3min to obtain the primary heating crystallization degree of the polyolefin, then cooling to less than or equal to 40 ℃ at 10 ℃ per minute, preserving heat for 3min, heating to 30 ℃ above the melting point of the polyolefin at 10 ℃ per minute for the second time, obtaining the secondary heating crystallization degree of the polyolefin, and directly reading the melting point temperature;
(2) Integrating the melting heat absorption curve, and calculating the area under the melting heat absorption curve to obtain a melting enthalpy value, wherein the unit is joule (J); the melting endothermic curve is a curve formed from the heating cycle beginning to the heat transfer enthalpy generation, and the melting enthalpy value is divided by the sample mass (g) to obtain the mass normalized melting enthalpy (delta H) of the sample s ) The crystallinity X (%) of the sample can then be calculated according to the following formula:
crystallinity X (%) =mass normalized melting enthalpy of sample (Δh) s ) 100% crystalline polyolefin melting enthalpy (DeltaH) f )×100％，
Wherein 100% of the crystalline polyolefin has a melting enthalpy (DeltaH) f )＝293.8J/g。
8. The membrane of claim 6 or 7, further comprising a membrane coating disposed on one or both sides of the membrane substrate.
9. The separator of claim 8, wherein the separator coating comprises one or more of an organic coating, an inorganic coating, an organic-inorganic composite coating.
10. The separator of claim 9, wherein the inorganic coating comprises a ceramic coating comprising at least one of: alumina, silica, titania, zirconia, zinc oxide, barium oxide, magnesium oxide, beryllium oxide, calcium oxide, thorium oxide, aluminum nitride, titanium nitride, boehmite, apatite, aluminum hydroxide, magnesium hydroxide, barium sulfate, boron nitride, silicon carbide, silicon nitride, cubic boron nitride, hexagonal boron nitride, mesoporous molecular sieve, and nacreous mica layer.
11. The separator of claim 9, wherein the organic coating comprises at least one of: polyvinylidene fluoride coating, vinylidene fluoride-hexafluoropropylene copolymer coating, polystyrene coating, aramid coating, polyacrylate or modified coating, polyester coating, polyarylate coating, polyacrylonitrile coating, aromatic polyamide coating, polyimide coating, polyethersulfone coating, polysulfone coating, polyetherketone coating, polyetherimide coating, polybenzimidazole coating, polydopamine coating.
12. A battery comprising a positive electrode, a negative electrode, an electrolyte, and the separator according to any one of claims 6 to 11.
13. An electronic device comprising a housing, a display screen housed within the housing, a circuit board assembly, and the battery of claim 12, the battery powering the display screen and the circuit board assembly.
14. A mobile device comprising the battery of claim 12.
15. A method of manufacturing a separator, comprising:
mixing a mixture comprising a plasticizer, the polyolefin powder of any of claims 1-2, and extruding from a screw extruder to form a gel sheet, the polyolefin powder comprising a plurality of polyethylenes having different viscosity average molecular weights;
Biaxially stretching the gel sheet;
removing plasticizer from the gel sheet;
heat setting the gel sheet, wherein the heat setting comprises low-rate stretching and retracting operations;
and rolling and cutting the gel sheet to form the diaphragm.
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| JP2019196470A (en) * | 2018-05-08 | 2019-11-14 | 有限会社ケー・イー・イー | Low heat shrinking polyolefin microporous film and its production method |
| CN111416086A (en) * | 2020-03-04 | 2020-07-14 | 华为技术有限公司 | Battery diaphragm and preparation method thereof, battery and terminal |
| WO2022002094A1 (en) * | 2020-07-01 | 2022-01-06 | 华为技术有限公司 | Separator and manufacturing method therefor, and battery, electronic device, and mobile device |
| CN113964448A (en) * | 2020-07-01 | 2022-01-21 | 华为技术有限公司 | Separator, method for manufacturing separator, battery, electronic device, and mobile device |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019196470A (en) * | 2018-05-08 | 2019-11-14 | 有限会社ケー・イー・イー | Low heat shrinking polyolefin microporous film and its production method |
| CN111416086A (en) * | 2020-03-04 | 2020-07-14 | 华为技术有限公司 | Battery diaphragm and preparation method thereof, battery and terminal |
| WO2022002094A1 (en) * | 2020-07-01 | 2022-01-06 | 华为技术有限公司 | Separator and manufacturing method therefor, and battery, electronic device, and mobile device |
| CN113964448A (en) * | 2020-07-01 | 2022-01-21 | 华为技术有限公司 | Separator, method for manufacturing separator, battery, electronic device, and mobile device |
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