CN106328868A - Heat shrinkage-resistant lithium ion battery diaphragm and extractant composition used by diaphragm - Google Patents
Heat shrinkage-resistant lithium ion battery diaphragm and extractant composition used by diaphragm Download PDFInfo
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- CN106328868A CN106328868A CN201510350307.9A CN201510350307A CN106328868A CN 106328868 A CN106328868 A CN 106328868A CN 201510350307 A CN201510350307 A CN 201510350307A CN 106328868 A CN106328868 A CN 106328868A
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- extractant
- thin film
- roller
- battery diaphragm
- lithium ion
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a heat shrinkage-resistant lithium ion battery diaphragm, a production method of the diaphragm, and an extractant composition used by the diaphragm. The extractant composition comprises a first extractant and a second extractant, the first extractant is a mixture comprising dichloromethane and phosphate ester, and the second extractant is water. The extractant composition provided the invention has a complete extraction effect on pore forming agents, and realizes less residual of the pore forming agents, and the battery diaphragm with good comprehensive performances can be produced from the pore forming agent, a specific pore forming agent and a specific ratio of macromolecular polyethylene and ultra-macromolecular polyethylene through a specific device by using a processing technology.
Description
Technical field
The present invention relates to the preparation technology of battery diaphragm, be specifically related to the lithium of a kind of resistance to thermal contraction
Ion battery barrier film, its preparation method and the extractant composition used.
Background technology
Lithium ion battery is widely used in the fields such as telecommunications, energy storage and electrical source of power, main
Will be made up of positive pole, negative pole, electrolyte and battery diaphragm, wherein, battery diaphragm is not lead
Electricity, between positive pole and negative pole, prevent the two short circuit because of contact, allow electricity simultaneously
Solving matter ion to pass through, thus produce electric current, current battery diaphragm mostly is has microcellular structure
Polyethylene composition film, its performance determines the interfacial structure of battery, internal resistance etc., directly
Affect the characteristics such as the capacity of battery, circulation and security performance, the battery diaphragm of excellent performance
The combination property improving battery had important function.
The performance of battery diaphragm mainly characterizes by following index: the property cut off requires battery diaphragm
There is partition property and electronic isolation, it is ensured that effective mechanical isolation of positive and negative electrode；Porosity
Require that barrier film has certain aperture and porosity, it is ensured that low resistance and high ion migration
Rate, has good permeability to lithium ion；Chemical stability and electrical stability require barrier film tool
Standby moisture-proof and electrolyte resistance corrosivity；Wellability requires the barrier film wellability to electrolyte
Good, and there is preferable imbibition moisture-retaining capacity and ion permeability；Mechanical strength requires barrier film
Enough mechanical properties and shock resistance is ensured, including puncturing while thickness is the least
Intensity and hot strength；Security requirement barrier film heat stability to be had and automatically shut down protection
Performance, including closed pore temperature and broken film temperature.It is phase between the multinomial performance index of battery diaphragm
Mutual correlation, it is desirable to take into account multinomial performance, obtain indices all preferably battery diaphragm mesh
Before still there is bigger difficulty.
Existing polyethylene composition battery diaphragm preparation method is broadly divided into wet method and dry method,
Wherein the preparation process of wet method includes: add little for high boiling point molecule to poly-second as pore former
In ene compositions, heating is melt into homogeneous system, and then cooling occurs to be separated, through two-way
Extract little molecule with organic solvent after stretching, the micro-pore septum being mutually communicated can be prepared.
There are some defects in traditional battery diaphragm wet method preparation process, including: use single
Liquid or the Organic substance of oily be pore former, the occupy-place effect of pore former is poor, battery diaphragm
The shapes and sizes of interior microcellular structure are almost determined by posterior drawing process completely, controllability
Difference, and the porosity of battery diaphragm and the air permeability that prepare are relatively low；Use single organic molten
Agent is extractant, and such as: dichloromethane, extraction not exclusively, still has part to become in battery diaphragm
Hole agent residual, not only causes the porosity of battery diaphragm and air permeability low, have an effect on battery every
The performance of film.
Above-mentioned condition based on prior art, the preparation technology of battery diaphragm is entered by the present inventor
Row research, it is therefore an objective to the lithium ion battery separator of a kind of resistance to thermal contraction is provided and is used
Extractant composition.
Summary of the invention
In order to overcome the problems referred to above, the preparation method of battery diaphragm has been carried out sharp by the present inventor
Meaning research, found that: by use specific Organic substance and inorganic matter as pore former,
More preferable occupy-place effect can be played, better control over the formation size of micropore, shape and distribution,
And be conducive to improving porosity and the air permeability of battery diaphragm, it addition, use suitably extraction
Above two pore former component is extracted by agent, and effect of extracting is more preferable, and pore former remains more
Few, above-mentioned pore former and extractant coordinate high-molecular polythene and the supra polymer of specific proportioning
Polyethylene is raw material, and after specific device and processing technique, can obtain having the resistance to of excellence
Heat-shrinkable and the battery diaphragm of good combination property, thus complete the present invention.
Therefore, it is an object of the invention to provide following aspect:
(1) the extractant combination of a kind of lithium ion battery separator for preparing resistance to thermal contraction
Thing, said composition includes the first extractant and the second extractant, wherein,
Described first extractant is the mixture of dichloromethane and phosphate ester composition,
Described second extractant is water.
(2) preparation method of the lithium ion battery separator of a kind of resistance to thermal contraction, the method bag
Include:
Step 1), extrusion: by polyethylene or a combination thereof thing, pore former and optional additive
Melting mixing, extrudes casting films；
Step 2), slab: step 1) casting films extruded flows through the first slab roller 3 and second
Space between slab roller 4, casts sheet；
Step 3), longitudinal stretching: step 2) obtain the most preheated roller of sheet, stretching
Roller and chill roll carry out longitudinal stretching, obtain thin film；
Step 4), cross directional stretch for the first time: step 3) the thin film both sides that obtain fix, depend on
Secondary carry out cross directional stretch through the first preheating zone, the first drawing zone and the first cooling zone；
Step 5), extraction: step 4) thin film that obtains is through the extraction as described in above-mentioned (1)
Agent compositions-treated, is then dried；
Step 6), cross directional stretch for the second time: step 5) the thin film both sides that obtain fix, depend on
Secondary carry out cross directional stretch through the second preheating zone, the second drawing zone and the second cooling zone, obtain resistance to
The lithium ion battery separator of thermal contraction.
(3) lithium ion battery of the resistance to thermal contraction prepared according to above-mentioned (2) described method every
Film, this barrier film includes first outer layer the 9, second outer layer 10 and is clipped in internal layer 11 therebetween,
Described first outer layer the 9, second outer layer 10 and internal layer 11 have different microcellular structures,
The average pore size of the most described first outer layer 9 is 20～100nm, putting down of the second outer layer 10
All apertures are 30～140nm, and the aperture of internal layer 11 is 50～180nm.
(4) device that a kind of enforcement above-mentioned (2) described preparation method is used, it includes
Extrusion device, cooling roller device and drying device, wherein,
Described extrusion device includes machine barrel, is disposed in parallel in two poly-second of described machine barrel one end
Ene compositions charging aperture 1 and be respectively arranged on described machine barrel to enter away from described polyethylene composition
Material mouth 1 is two pore former charging apertures 2 at 1/3 and 2/3 barrel length,
Described cooling roller device includes the first slab roller 3 and second that spacing is 180～580 μm
Slab roller 4, the diameter of described first slab roller 3 and the second slab roller 4 is than for 1:(1～6),
Described first slab roller 3 and the second slab roller 4 rotate in opposite directions, it is preferable that described first slab
The roller linear velocity of roller 3 and the roller linear velocity numerical value of described second slab roller 4 are equal,
Described drying device includes the transfer roller 6 that multiple one-tenth broken line is arranged, in thin film and transmission
The position that roller 6 contacts is provided with for dry air gun 7, the jet of the most described air gun 7
Direction and the plane tangent of described transfer roller 6 or parallel with the direction of transfer of thin film.
The present invention described below.
According to the first aspect of the invention, it is provided that a kind of lithium ion for preparing resistance to thermal contraction
The extractant composition of battery diaphragm, said composition includes the first extractant and the second extraction
Agent.
Described first extractant is the mixture of dichloromethane and phosphate ester composition, preferably described
Phosphate ester is one or more in trimethyl phosphate or triethyl phosphate.
Described second extractant is water.
Described extractant composition coordinates specific pore former, for preparing the lithium of resistance to thermal contraction
Ion battery barrier film, described specific pore former includes organic pore former and Inorganic pore forming agents,
Described organic pore former is high boiling point small organic molecule, and described Inorganic pore forming agents is water solublity
The nano-particle of inorganic salt.
In a preferred embodiment in accordance with the present invention, described organic pore former is preferably mineral
Oil, C6-15Alkane, C8-15Aliphatic carboxylic acid, C1-4Alkyl ester, C2-6One in halogenated alkane or
Several.
Wherein, described mineral oil is preferably white oil；
Described C6-15Alkane is preferably in heptane, naphthalane, decane, hendecane and dodecane
One or more；
Described C8-15Aliphatic carboxylic acid is preferably the one in capric acid, hendecoic acid and lauric acid
Or it is several；
Described C1-4Alkyl ester is just being preferably methyl caprate, ethyl caprate, capric acid propyl ester, capric acid
Butyl ester, hendecoic acid methyl ester, hendecoic acid ethyl ester, hendecoic acid propyl ester, hendecoic acid are just
Butyl ester, lauric acid methyl ester, dodecanoate, lauric acid propyl ester and lauric acid are just
One or more in butyl ester；
Described C2-6Halogenated alkane is preferably dichloroethanes, dichloropropane, chlorofluoroethane and fluorine
One or more in chloropropane.
Described organic pore former more preferably mineral oil, more preferably white oil.
In a preferred embodiment in accordance with the present invention, described Inorganic pore forming agents is the most water-soluble
One or several in the nano-particle of property sulfate, water-soluble nitrate and water-soluble hydrochloride salt
Kind.
Wherein, during described water soluble sulfate is preferably sodium sulfate, potassium sulfate and ammonium sulfate
One or more；
Described water-soluble nitrate be preferably sodium nitrate, potassium nitrate, ammonium nitrate, magnesium nitrate and
One or more in copper nitrate；
Described water-soluble hydrochloride salt be preferably sodium chloride, potassium chloride, ammonium chloride, magnesium chloride,
One or more in calcium chloride and copper chloride.
The particle diameter of described Inorganic pore forming agents is 5～200nm, and preferably 8～100nm are more excellent
Elect 10～50nm as.
In a preferred embodiment in accordance with the present invention, described pore former be more preferably white oil and
The compositions that magnesium chloride nano-particle is constituted.
In a preferred embodiment in accordance with the present invention, preferably by described pore former and polyethylene
Compositions mixes, and prepares three kinds of microcellular structure battery diaphragms, wherein, described organic pore former
Addition be preferably the 30～60% of polyethylene composition weight, described Inorganic pore forming agents
Addition is preferably the 1～10% of polyethylene composition weight.
Compared to liquid or the organic pore former of oily, the inorganic pore-forming of described solid granular
Agent has bigger particle diameter and fixing form, thus has higher occupy-place effect, can be
Form the microcellular structure that aperture is bigger in battery diaphragm, can better control over and form the big of micropore
Little, shape and distribution, and be conducive to improving porosity and the air permeability of battery diaphragm, such as:
Can by select different-grain diameter Inorganic pore forming agents prepare the different battery of micropore size every
Film.
In a preferred embodiment in accordance with the present invention, the most above-mentioned pore former is entered
Row extraction, first extracts the organic pore former component in pore former, then uses with the first extractant
Second extractant extracts the Inorganic pore forming agents component in pore former.With the first extractant and
When two extractants soak thin film, it is evenly distributed on that pore former thin film within is dissolved to be extracted,
Whether microcellular structure, the distribution of micropore and aperture is formed in the position originally occupied by pore former
Uniformly it is distributed the most dispersed directly related in thin film with pore creating material.
Described first extractant is good to the organic pore former component dissolubility in pore former, and
Polyethylene composition in insoluble thin film and the reagent of additive, the present invention preferably selects
The mixture of dichloromethane and phosphate ester composition, described phosphate ester be preferably trimethyl phosphate and
One or more in triethyl phosphate, wherein, dichloromethane with the weight ratio of phosphate ester is
10:1～40:1, preferably 15:1～30:1, described first extractant extraction to organic pore former
Taking effect and be better than simple dichloromethane, extraction is more complete, and pore former residual is few.
Described second extractant is good to the Inorganic pore forming agents component dissolubility in pore former, and
Polyethylene composition in insoluble thin film and the reagent of additive, the present invention preferably selects
Water, more preferably high purity water.
According to the second aspect of the invention, it is provided that the lithium ion battery separator of a kind of resistance to thermal contraction
Preparation method, the method comprises the following steps:
Step 1), extrusion: by polyethylene or a combination thereof thing, pore former and optional additive
Melting mixing, extrudes casting films.
In a preferred embodiment in accordance with the present invention, described polyethylene composition includes
93～98 weight portion high-molecular polythenes and 2～7 weight portion ultra high molecular polyethylenes, preferably include
94～96 weight portion high-molecular polythenes and 3～6 weight portion ultra high molecular polyethylenes, more preferably wrap
Include 95 weight portion high-molecular polythenes and 5 weight portion ultra high molecular polyethylenes.
Wherein, the number-average molecular weight of described high-molecular polythene is 100,000～600,000, is preferably
200000～500,000, more preferably 300,000～400,000, the equal molecule of number of described ultra high molecular polyethylene
Amount is 1,200,000～1,500,000, preferably 1,300,000～1,400,000.
Described additive preferably includes antioxidant, anti ultraviolet agent, antistatic additive and antifoggant
In one or more, described additive mixes the most according to the following ratio:
Antioxidant, 0.1～20 weight portions；
Anti ultraviolet agent, 0.1～15 weight portions；
Antistatic additive, 0.1～25 weight portions；
Antifoggant, 0.1～20 weight portions.
Wherein, described antioxidant is selected from 4,4-thiobis (6-tert-butyl-m-cresol), two fourths
Base hydroxy-methylbenzene, tert-butyl hydroquinone, preferably 4,4-thiobis (6-tert-butyl-m-cresol)；
Described anti ultraviolet agent is selected from salicylic acid esters, benzophenone class, benzotriazole, replacement third
Alkene nitrile, triazines and hindered amines, preferably oxybenzoic acid phenyl ester, 2-(2-hydroxyl
Base-5-aminomethyl phenyl) BTA, 2,4-DihydroxyBenzophenone, 2-hydroxyl-4-first
Epoxide benzophenone, Octabenzone, 2-(2 '-hydroxyl-3 ', 5 '-two
Tertiary phenyl)-5-chlorination benzotriazole, single benzoic acid resorcinol, three (1,2,2,6,
6-pempidine base) phosphite ester, 4-benzoyloxy-2,2,6,6-tetramethyl piperidines,
2,4,6-tri-(2 '-n-butoxyphenyl)-1,3,5-triazines and HMPA etc.；
Described antistatic additive is selected from cationic antistatic agent, anionic antistatic agents and nonionic
Antistatic additive, is preferably selected from quaternary ammonium salt, ethoxy alkylation aliphatic alkyl amine, such as ten
Eight quaternary ammonium alkyl sodium；
Described antifoggant is selected from the ester of xylitol, sorbitol palmitate, lauric acid, span
Series of surfactants, TWEEN Series surfactant or animi resin monoglyceride, preferably
For span series and TWEEN Series surfactant.
In a preferred embodiment in accordance with the present invention, described melting mixing the process extruded
Extruder or extrusion device are carried out, described extruder or extrusion device include machine barrel and
Row are arranged on two polyethylene composition charging apertures of described machine barrel one end and are respectively arranged at
On described machine barrel away from described polyethylene composition charging aperture be at 1/3 and 2/3 barrel length two
Individual pore former charging aperture.
After polyethylene composition, Inorganic pore forming agents and optional additive being pre-mixed uniformly
Put into extruder, preferably Inorganic pore forming agents and high-molecular polythene are pre-mixed uniformly, will
Optional additive and ultra high molecular polyethylene are pre-mixed uniformly, put into extruder, then
Add heat fusing, the extrusion direction of the polyethylene composition of extruder inner molten there was added
Machine pore former, described organic pore former is preferably dividedly in some parts extruder, melted and mix homogeneously
Rear extrusion casting films, use above-mentioned preferred mode add described Inorganic pore forming agents with organic become
Hole agent, can avoid polyethylene composition and pore former to occur being separated and causing mixing inequality also
With pressure oscillation in extruder so that polyethylene composition and pore former are sufficiently mixed all
Even, pore former is uniformly distributed in polyethylene composition mixture, beneficially in subsequent step
The aperture preparing micropore and the battery diaphragm being more evenly distributed.
In a preferred embodiment in accordance with the present invention, described polyethylene composition, pore former
Can first mix with optional additive, be again heated to molten condition, it is also possible to add the most respectively
Heat fusing, more melted above-mentioned substance is mixed, the present invention is the most first by described poly-
Vinyl composition, pore former and optional additive mix homogeneously respectively, adds extruder
In be heated to molten condition and stir mixing, mix homogeneously, and easy and simple to handle, energy consumption is low.
In a preferred embodiment in accordance with the present invention, extrusion temperature and the direct shadow of rate of extrusion
Ring step 2) in prepare the character of sheet and thickness, and determine finally to prepare each of barrier film
Item physicochemical property.Extrusion temperature is the highest, and the mobility of casting films is the best, molecule confusion degree
The highest, the crystallinity preparing barrier film is the poorest；Extrusion temperature is the lowest, and the mobility of casting films is more
Difference, molecule confusion degree is the lowest, and degree of molecular orientation is the highest, and the crystallinity preparing barrier film is the best,
In the present invention, extrusion temperature is 150～250 DEG C, preferably 170～240 DEG C.Rate of extrusion is too fast,
Casting films is piled up too much between the first slab roller and the second slab roller, is likely to result in local cold
The most hardening and affect slab and carry out；Rate of extrusion is the slowest, is likely to result in prepared slab thicknesses
Uneven or the thinnest, in the present invention, rate of extrusion is 800～2000g/min, is preferably
1000～1500g/min.
Step 2), slab: step 1) casting films extruded flows through the first slab roller and second
Space between slab roller, casts sheet.
In a preferred embodiment in accordance with the present invention, described slab process is at cooling roller device
In carry out, described cooling roller device includes the first slab roller and that spacing is 180～580 μm
Two slab rollers, the diameter of described first slab roller and the second slab roller is than for 1:(1～6), institute
State the first slab roller and the second slab roller rotates in opposite directions, it is preferable that described first slab roller
The roller linear velocity numerical value of roller linear velocity and described second slab roller is equal.
Described first slab roller and the second slab roller opposite direction rotating, from extruder die head extrusion
Casting films forms accumulation between the first slab roller and the second slab roller, is then passed through the two it
Between space extruding, cooling, cast sheet, reduce that rate of extrusion is uneven, extruder machine
The factor impacts on sheet character such as tool concussion, thus prepare that thickness is uniform, character is stable
Sheet.
In a preferred embodiment in accordance with the present invention, described first slab roller and the second slab
The temperature of roller is 5～40 DEG C, preferably 10～35 DEG C, more preferably 12～33 DEG C, the stream of extrusion
Prolong film and flow through two-sided cooling molding during the space between the first slab roller and the second slab roller, casting
Become sheet, meanwhile, be uniformly distributed pore former therein, with polyethylene composition, heat occur
Cause is separated, and pore former is closed therein by the sheet of two-sided cooling, with traditional handicraft
The sheet of middle one side cooling is compared, and pore former is less susceptible to ooze out, and is conducive to preparing the hole of micropore
The more uniform battery diaphragm of footpath, distribution.
In a preferred embodiment in accordance with the present invention, optionally by described first slab roller or the
The surface of two slab rollers is processed into rough plane, can prepare the electricity that single or double is coarse
Pond barrier film, improves the membrane surface bonding to other material (such as: coating, film etc.)
Ability, lays a good foundation for research and development novel battery barrier film.
In a preferred embodiment in accordance with the present invention, the thickness of described sheet directly affects
Preparing the thickness of barrier film eventually, in general, sheet is the thickest, and the barrier film prepared is the thickest, can lead to
Overregulate the gap length between the first slab roller and the second slab roller to regulate the thickness of sheet
Degree, the thickness of heretofore described sheet is 200～600 μm, preferably 250～550 μm,
More preferably 300～500 μm.
Step 3), longitudinal stretching: step 2) obtain the most preheated roller of sheet, stretching
Roller and chill roll carry out longitudinal stretching.
In a preferred embodiment in accordance with the present invention, the most preheated roller of described sheet is with relatively
Low temperature preheats, and softens sheet, prepares for stretching, prevents sheet because of unexpected high-temperature heating
And cause character cataclysm；Then, the draw roll that described sheet gradually rises through multiple rotating speeds exists
Longitudinal stretching is carried out under high temperature；Finally, cooled roller sub-cooled is shaped, and obtains character solid
Fixed thin film.After longitudinal stretching, thin film elongates compared with sheet in the vertical, and thickness becomes
Thin, and longitudinal mechanical strength is improved, meanwhile, the micropore of its internal pore former occupy-place is indulged
To being elongated to elongate.
In a preferred embodiment in accordance with the present invention, the temperature of described pre-hot-rolling is
40～130 DEG C, preferably 50～120 DEG C, more preferably 60～110 DEG C, preheat sheet, for drawing
Stretch and prepare；
The temperature of described draw roll is 70～150 DEG C, preferably 80～140 DEG C, more preferably
90～130 DEG C, while ensureing the good tensile property of sheet, make the micropore of pore former occupy-place
Reach suitable aperture；
The temperature of described chill roll is 3～50 DEG C, preferably 5～45 DEG C, more preferably 8～40 DEG C,
Make the rapid cooling and shaping of the thin film after drawing by high temperature, keep the length after longitudinal stretching, thickness
Degree and aperture.
In a preferred embodiment in accordance with the present invention, the rotating speed of the plurality of draw roll exists
In the range of 2～40m/min, gradient raises so that stretching is uniform, by turning of regulation draw roll
Speed regulates the longitudinal stretching degree of thin film, obtains different ratios of elongation.
The ratio of elongation of described longitudinal stretching is 3～10, preferably 3.5～9.5, more preferably 4～9,
Obtain that there is suitable thickness, aperture and the thin film of longitudinal mechanical strength.
Step 4), cross directional stretch for the first time: step 3) the thin film both sides that obtain fix, depend on
Secondary carry out cross directional stretch through the first preheating zone, the first drawing zone and the first cooling zone.
In a preferred embodiment in accordance with the present invention, the both sides fixture of described thin film is solid
Fixed, first pass around the first preheating zone and preheat, soften thin film, prepare for stretching；So
After, at high temperature carrying out cross directional stretch through the first drawing zone, symmetrical spacing jig is from gradually
Increase；Finally, through the first cooling zone sub-cooled sizing, the thin film that character is fixing is obtained.
After first time cross directional stretch, thin film elongates in the horizontal, lower thickness, and laterally machinery
Intensity is improved, and meanwhile, the micropore horizontal elongation of its internal pore former occupy-place becomes similar circle
Shape.
In a preferred embodiment in accordance with the present invention, the temperature of described first preheating zone is
60～150 DEG C, preferably 70～140 DEG C, more preferably 75～135 DEG C, preheated film, for drawing
Stretch and prepare；
The temperature of described first drawing zone is 80～150 DEG C, preferably 85～145 DEG C, more preferably
It is 90～140 DEG C, while ensureing the good tensile property of thin film, makes the micro-of pore former occupy-place
Hole reaches suitable aperture；
The temperature of described first cooling zone is 60～150 DEG C, preferably 70～140 DEG C, more preferably
It is 75～135 DEG C so that the rapid cooling and shaping of thin film after drawing by high temperature, keeps the most horizontal
Length, thickness and aperture after stretching.
In a preferred embodiment in accordance with the present invention, described thin film the most at the uniform velocity moves
Dynamic, regulate the cross directional stretch degree of thin film by regulating the distance between horizontal fixture, obtain
Different ratios of elongation.
The ratio of elongation of described first time cross directional stretch is 3～11, and preferably 3.5～10.5 are more excellent
Elect 4～10 as, obtain that there is suitable thickness, aperture and the thin film of horizontal mechanical strength.
Step 5), extraction: step 4) thin film that obtains combines through extractant as above
Thing processes, and is then dried.
In a preferred embodiment in accordance with the present invention, described extractant includes the first extractant
With the second extractant, step 4) thin film that obtains is successively through the first extractant and the second extraction
Agent immersion treatment.
Drying device is dried.Described drying device includes what multiple one-tenth broken line was arranged
Transfer roller.In a preferred embodiment in accordance with the present invention, contact with transfer roller at thin film
Position be provided with for dry air gun, the jet direction of the most described air gun and described biography
Send the plane tangent of roller or parallel with the direction of transfer of thin film.
Use air gun that the thin film after extraction is dried, to remove the extraction of film surface residual
Taking agent, prevent stain mark, described air gun drying effect is good, and effectively prevent thin film
The generation of surface water wave stricture of vagina, meanwhile, by the position of Reasonable adjustment air gun Yu thin film so that
The vertical impact forces of thin film is obviously reduced by air gun, significantly improves final prepared battery diaphragm
The bad phenomenon such as outward appearance fold, scollop, scallop.
Step 6), cross directional stretch for the second time: step 5) the thin film both sides that obtain fix, depend on
Secondary carry out cross directional stretch through the second preheating zone, the second drawing zone and the second cooling zone, obtain resistance to
The lithium ion battery separator of thermal contraction.
In a preferred embodiment in accordance with the present invention, the both sides fixture of described thin film is solid
Fixed, first pass around the second preheating zone and preheat, soften thin film, prepare for stretching；So
After, at high temperature carry out small size cross directional stretch through the second drawing zone, symmetrical spacing jig from
It is gradually increased；Finally, through the second cooling zone sub-cooled sizing, obtain that character is fixing three
Plant the battery diaphragm of microcellular structure.Cross directional stretch is compared with first time cross directional stretch for the second time,
Level of stretch substantially reduces, and after second time cross directional stretch, the thin film with microcellular structure exists
The most slightly elongate or keep constant, by heating-cooling process make its mechanical strength,
Air permeability, thermal contraction performance improve further, meanwhile, and its internal micropore horizontal elongation,
Aperture increases, and obtains the lithium ion battery separator with the resistance to thermal contraction of good character.
In a preferred embodiment in accordance with the present invention, the temperature of described second preheating zone is
70～160 DEG C, preferably 80～150 DEG C, more preferably 90～140 DEG C, preheated film, for drawing
Stretch and prepare；
The temperature of described second drawing zone is 100～155 DEG C, preferably 105～150 DEG C, more excellent
Elect 110～145 DEG C as, make micropore reach to close while ensureing the good tensile property of thin film
Suitable aperture；
The temperature of described second cooling zone is 60～130 DEG C, preferably 65～135 DEG C, more preferably
It is 70～130 DEG C so that the rapid cooling and shaping of thin film after drawing by high temperature, keeps second time horizontal
Length, thickness and aperture after stretching.
In a preferred embodiment in accordance with the present invention, described thin film the most at the uniform velocity moves
Dynamic, regulate the cross directional stretch degree of thin film by regulating the distance between horizontal fixture, obtain
Different ratios of elongation.
The ratio of elongation of described second time cross directional stretch is 0.5～5, preferably 0.7～4, more preferably
It is 0.8～3, obtains the electricity with suitable thickness, aperture, mechanical strength and thermal contraction performance
Pond barrier film.
According to the third aspect of the invention we, it is provided that use heat-resisting receipts prepared by method as defined above
The lithium ion battery separator of contracting, this battery diaphragm includes the first outer layer, the second outer layer and is clipped in
Therebetween internal layer, described first outer layer, the second outer layer and internal layer have different micropores
Structure.
In a preferred embodiment in accordance with the present invention, the aperture of described first outer layer is
20～100nm, the aperture of the second outer layer is 30～140nm, and the aperture of internal layer is 50～180
nm。
Being to be mutually related between the multinomial performance index of battery diaphragm, the barrier film that thickness is less is past
Relatively low toward hot strength and puncture strength, the most damaged in battery installation process；Machinery is strong
The general fusing point of polyethylene composition material spending higher barrier film employing is higher, therefore closed pore temperature
Spend higher, poor stability, although raw materials for production or the working condition that can change barrier film come bright
Aobvious some performance indications of raising, but want to take into account multinomial performance, obtain indices the most relatively
Good battery diaphragm the most still has bigger difficulty.
The present invention, by using specific Organic substance and inorganic matter as pore former, can play more
Good occupy-place effect, better controls over and forms the size of micropore, shape and distribution, and favorably
In porosity and the air permeability of raising battery diaphragm, it addition, use suitable extractant to combine
Above two pore former component is extracted by thing, and effect of extracting is more preferable, and pore former remains more
Few, above-mentioned pore former and extractant coordinate high-molecular polythene and the supra polymer of specific proportioning
Polyethylene is raw material, and after specific device and processing technique, prepares and have the heat-resisting of excellence
Contractility, and the battery diaphragm of good combination property.
In a preferred embodiment in accordance with the present invention, the performance of described battery diaphragm is as follows:
Thickness is 5～25 μm, preferably 8～22 μm, more preferably 10～18 μm；
Porosity is 40～90%, preferably 42～80%, more preferably 44～75%；
Venting quality is 200～400sec/100ml, and preferably 220～380sec/100ml are more excellent
Elect 250～350sec/100ml as；
Longitudinal tensile strength is 1800～2200kgf/cm2, preferably 1850～2150
kgf/cm2, more preferably 1900～2100kgf/cm2；
Transverse tensile strength is 1800～2500kgf/cm2, preferably 1900～2450
kgf/cm2, more preferably 2000～2400kgf/cm2；
Puncture strength is 600～1000gf, preferably 640～950gf, more preferably 660～900
gf；
Longitudinal extension rate is 160～220%, preferably 170～210%, more preferably
180～200%；
Horizontal expansion rate is 150～210%, preferably 160～200%, more preferably
170～195%；
Longitudinal percent thermal shrinkage is not more than 0.5%, and preferably no greater than 0.3%, more preferably no more than
0.1%；
Laterally percent thermal shrinkage is not more than 0.3%, and preferably no greater than 0.2%, more preferably no more than
0.1%；
Closed pore temperature is 120～150 DEG C, preferably 130～148 DEG C, more preferably
138～142 DEG C；
Broken film temperature is 160～180 DEG C, preferably 163～175 DEG C, more preferably
166～172 DEG C.
The battery diaphragm that the method using the present invention to provide prepares has the resistance to thermal contraction of excellence
Property, percent thermal shrinkage is extremely low, significantly reduces during the use of battery because barrier film is heated receipts
Contract and cause the problems such as battery open circuit, keep good combination property simultaneously, relatively low at thickness
While there is higher hot strength and puncture strength, can be used for preparing the electricity that volume is less
Pond, and higher mechanical force, not cracky can be born in battery assembling process；It addition,
Porosity and venting quality are high, and low with its internal resistance of cell prepared, capacitance improves relatively；With
Time, there is relatively low closed pore temperature and higher broken film temperature, safety is high.
According to the present invention, the preparation method of the lithium ion battery separator of resistance to thermal contraction described above
The device used includes extrusion device, cooling roller device and drying device.
Described extrusion device includes machine barrel, is disposed in parallel in two poly-second of described machine barrel one end
Ene compositions charging aperture and be respectively arranged on described machine barrel to enter away from described polyethylene composition
Material mouth is two pore former charging apertures at 1/3 and 2/3 barrel length.
Described cooling roller device includes the first slab roller and second that spacing is 180～580 μm
Slab roller, the diameter of described first slab roller and the second slab roller is than for 1:(1～6), described
First slab roller and the second slab roller rotate in opposite directions, it is preferable that the roller of described first slab roller
The roller linear velocity numerical value of cylinder linear velocity and described second slab roller 4 is equal.
Described drying device includes the transfer roller that multiple one-tenth broken line is arranged, at thin film and transfer roller
The position contacted is provided with for dry air gun, the jet direction of the most described air gun with
The plane tangent of described transfer roller or parallel with the direction of transfer of thin film.
As fully visible, the present invention is had the advantage that and is included following all many-sides:
(1) extraction of the lithium ion battery separator for preparing resistance to thermal contraction that the present invention provides
Take agent compositions and include the first extractant and the second extractant, coordinate specific pore former,
The most successively two kinds of pore former components are extracted during extraction, use dichloromethane
The mixture that alkane and phosphate ester form in specific proportions is the first extractant, is used for extracting organic
Pore former, adopts and uses water as the second extractant, is used for extracting Inorganic pore forming agents, extracts completeer
Entirely, pore former residual is few；
(2) preparation method of the lithium ion battery separator of the resistance to thermal contraction that the present invention provides is adopted
High-molecular polythene and ultra high molecular polyethylene by specific proportioning are raw material, select and add
Suitably pore former and/or additive, after specific device and processing technique, prepares described
The lithium ion battery separator of resistance to thermal contraction so that this barrier film has the thermal shrinkage of excellence,
And good combination property, there is relatively low closed pore temperature, higher broken film temperature and good machine
Tool intensity；
(3) preparation method of the lithium ion battery separator of the resistance to thermal contraction that the present invention provides exists
During extrusion, Inorganic pore forming agents is first mixed with polyethylene composition, in extrusion
Organic pore former is dividedly in some parts, prevent pore former and polyethylene composition from occurring to be separated and
Cause extruder pressure fluctuating in inner, cause rate of extrusion uneven, steady extruding casting films,
Make the slab thicknesses cast uniform；
(4) preparation method of the lithium ion battery separator of the resistance to thermal contraction that the present invention provides exists
The while of using the first slab roller and second slab roller with refrigerating function during slab
Carry out two-sided cooling slab, thus pore former is preferably enclosed in inside sheet, and cast
Slab thicknesses uniformly, stable；Meanwhile, optionally the surface of slab roller is processed into rough
Plane, can prepare the more preferable shaggy battery diaphragm of cohesive, is conducive to developing novel
Battery diaphragm；
(5) preparation method of the lithium ion battery separator of the resistance to thermal contraction that the present invention provides exists
During longitudinal stretching, for the first time cross directional stretch and for the second time cross directional stretch, can be according to institute
The difference needing barrier film arranges different temperature, rotating speed and other parameters, thus prepares different thick
Degree, aperture, the battery diaphragm of microporosity, easy and simple to handle, controllability is strong, is widely used；
(6) preparation method of the lithium ion battery separator of the resistance to thermal contraction that the present invention provides exists
Changed the direction of advance of thin film into broken line by straight line during being dried after extraction, and use air gun
Substituted for original hydraulic giant, and make the jet direction of air gun think parallel with thin film direction of transfer,
Reach good drying effect, and effectively reduce prepared battery diaphragm surface ripples occur
The phenomenons such as stricture of vagina and outward appearance fold, scollop, scallop, beneficially rolling and improve making of battery diaphragm
The property used；
(7) the preparation side of the lithium ion battery separator of the resistance to thermal contraction of present invention offer is provided
The battery diaphragm that method prepares has a three-decker, and the micro-pore shape of every layer, aperture are the most different,
Micropore is evenly distributed, and porosity is high；
(8) the preparation side of the lithium ion battery separator of the resistance to thermal contraction of present invention offer is provided
The battery diaphragm that method prepares takes into account multinomial physicochemical property, good combination property, is reaching relatively low thickness
Possess high puncture strength and hot strength while degree, can be applicable to less battery and in peace
Not cracky in process of assembling；Having good air permeability and porosity, internal resistance is little, carries simultaneously
The capacity of high battery and cycle performance；It addition, also have relatively low closed pore temperature and rupture of membranes temperature
Degree, safety is high.
Accompanying drawing explanation
Fig. 1 illustrates the extrusion device schematic diagram according to one embodiment of the present invention；
Fig. 2 illustrates the cooling roller device schematic diagram according to one embodiment of the present invention；
Fig. 3 illustrates the drying device schematic diagram according to one embodiment of the present invention；
Fig. 4 illustrates the drying device schematic diagram in traditional processing technology；
Fig. 5 illustrate the lithium ion battery of the resistance to thermal contraction according to one embodiment of the present invention every
Film representative side section view.
Drawing reference numeral explanation
1-polyethylene composition charging aperture
2-pore former charging aperture
3-the first slab roller
4-the second slab roller
5-extruder die head
6-transfer roller
7-air gun
8-hydraulic giant
9-the first outer layer
10-the second outer layer
11-internal layer
Detailed description of the invention
Below by drawings and Examples, the present invention is described in more detail.Said by these
Bright, the features and advantages of the invention will become more apparent from clearly.
According to the present invention, the preparation method of the lithium ion battery separator of resistance to thermal contraction uses specific
Device, this device includes extrusion device, cooling roller device and drying device, specific as follows:
Extrusion device
As it is shown in figure 1, described extrusion device includes polyethylene composition charging aperture 1 and pore former
Charging aperture 2.
In a preferred embodiment in accordance with the present invention, described extrusion device preferably includes two
Polyethylene composition charging aperture 1 and two pore former charging apertures 2.
Described extrusion device also includes machine barrel, and said two polyethylene composition charging aperture 1 is also
Row are arranged at one end of described machine barrel, and said two pore former charging aperture 2 is respectively arranged at institute
State on machine barrel away from described polyethylene composition charging aperture 1 be at 1/3 and 2/3 barrel length.
In a preferred embodiment in accordance with the present invention, polyethylene or a combination thereof thing, inorganic one-tenth
Hole agent and optional additive enter through said two polyethylene composition after being pre-mixed uniformly
Material mouth 1 adds described extrusion device, preferably by Inorganic pore forming agents with high-molecular polythene in advance
Mix homogeneously, is pre-mixed uniformly by optional additive and ultra high molecular polyethylene, above-mentioned
Two kinds of mixture add described extrusion dress through said two polyethylene composition charging aperture 1 respectively
Put, be more easy to mix homogeneously.
Said mixture is heated to molten condition and along described machine barrel in described extrusion device
Extrusion, adds organic pore former through said two pore former charging aperture 2 in extrusion direction,
Extrude casting films after melted also mix homogeneously, polyethylene composition and pore former can be avoided to occur
It is separated and causes mixing inequality and with pressure oscillation in extruder so that polyethylene composition
Thing and pore former are sufficiently mixed uniformly, and pore former is uniformly distributed in polyethylene composition mixture
In, the aperture beneficially preparing micropore in subsequent step and the battery that is more evenly distributed every
Film.
Cooling roller device
As in figure 2 it is shown, described cooling roller device includes that axis is positioned in same level
One slab roller 3 and the second slab roller 4, between described first slab roller 3 and the second slab roller 4
Spacing is 180-580 μm, preferably 230-530 μm, more preferably 280-480 μm.
In a preferred embodiment in accordance with the present invention, described first slab roller 3 and the second casting
Sheet roller 4 opposite direction rotating, from the casting films of extruder die head 5 extrusion at the first slab roller 3 and the
Formed between two slab rollers 4 and pile up, be then passed through space extruding therebetween, cooling,
Casting sheet, the factors such as rate of extrusion inequality, extruder machinery concussion that reduce are to sheet
The impact of shape, thus prepare the sheet that thickness is uniform, character is stable.
In a preferred embodiment in accordance with the present invention, described first slab roller 3 and the second casting
The diameter of sheet roller 4 is than for 1:(1～6), preferably 1:(2～5), more preferably 1:(3～4),
A diameter of 300-600mm of the most described first slab roller 3, the second slab roller 4 a diameter of
500-900mm。
At the chiller that is internally provided with of described first slab roller 3 and the second slab roller 4, use
In controlling the first slab roller 3 and temperature on the second slab roller 4 surface, thus the curtain coating to extrusion
Film cools down, and the temperature of the most described first slab roller 3 and the second slab roller 4 is
5～40 DEG C, preferably 10～35 DEG C, more preferably 12～33 DEG C, the casting films of extrusion flows through
Two-sided cooling molding during space between one slab roller 3 and the second slab roller 4, casts sheet,
Meanwhile, being uniformly distributed pore former therein occurs thermotropic phase to divide with polyethylene composition
From, pore former is closed therein by the sheet of two-sided cooling, cold with one side in traditional handicraft
But sheet is compared, and pore former is less susceptible to ooze out, and is conducive to preparing the aperture of micropore, distribution
More uniform battery diaphragm.
In a preferred embodiment in accordance with the present invention, optionally by described first slab roller 3 or
The surface of the second slab roller 4 is processed into rough plane, can prepare single or double coarse
Battery diaphragm, improve membrane surface to other material (such as coating, film etc.)
Adhesive power, lays a good foundation for research and development novel battery barrier film.
Drying device
As it is shown on figure 3, described drying device includes the transfer roller 6 that multiple one-tenth broken line is arranged,
The position that thin film contacts with transfer roller 6 is provided with for dry air gun 7.
In a preferred embodiment in accordance with the present invention, the jet direction of described air gun 7 and institute
State the plane tangent of transfer roller 6 or parallel with the direction of transfer of thin film.
In a preferred embodiment in accordance with the present invention, the thin film after extraction is through multiple transfer rollers
6 advance along broken line, and the position contacted with each transfer roller 6 at thin film is provided with for being dried
Air gun 7, with remove film surface residual extractant, prevent stain mark, described gas
The jet direction of rifle 7 and the plane tangent of transfer roller, i.e. parallel with the direction of transfer of thin film,
Drying effect is good, and effectively prevent the generation of film surface water ripples, meanwhile, air gun
The vertical impact forces of 7 pairs of thin film is obviously reduced, and significantly improves final preparing outside battery diaphragm
See the bad phenomenon such as fold, scollop, scallop.
Different from foregoing of the present invention, in traditional processing technology, as shown in Figure 4, extraction
Thin film after taking linearly transmits, and uses hydraulic giant 8 and air gun 7 mixing to be dried, and prepares
Film surface water ripples easily occur, cause the final battery diaphragm uneven thickness prepared or
Injustice, and hydraulic giant 8 and air gun 7 inject directly on the surface of thin film the most at a certain angle, impact
Power is big, and the phenomenon such as battery diaphragm outward appearance fold, scollop, scallop is serious, affects making of battery diaphragm
With and rolling.
According in one embodiment of the present invention, as it is shown in figure 5, described three kinds of micropores
Structure battery barrier film includes first outer layer the 9, second outer layer 10 and is clipped in internal layer therebetween
11, described first outer layer the 9, second outer layer 10 and internal layer 11 have different microcellular structures.
The aperture of described first outer layer 9 is 20～100nm, and the aperture of the second outer layer 10 is
30～140nm, the aperture of internal layer 11 is 50～180nm.
Embodiment
Embodiment 1
Following weight is included for preparing the compositions of the lithium ion battery separator of resistance to thermal contraction
The component of proportioning:
Wherein,
The number-average molecular weight of high-molecular polythene is 500,000,
The number-average molecular weight of ultra high molecular polyethylene is 1,400,000,
The mean molecule quantity of white oil is 200,
The particle diameter of nanometer magnesium chloride is 50～70nm.
Prepare the lithium ion battery separator of resistance to thermal contraction in accordance with the following methods:
Step 1), extrusion: by high-molecular polythene and magnesium chloride nano-particle mix homogeneously,
By ultra high molecular polyethylene, 4,4-thiobis (6-tert-butyl-m-cresol), 2,4-dihydroxy two
Benzophenone, octadecyl quaternary ammonium sodium and Tween 80 mix homogeneously, above two mixture is respectively
Put in extruder by two polyethylene composition charging apertures and add heat fusing, in extrusion direction
Being put into white oil by two pore former charging apertures by several times, extrude casting films, extrusion temperature is
210～240 DEG C, rate of extrusion is 1200g/min；
Step 2), slab: ganoid first slab roller 3 and the second slab roller 4 is set
Temperature be 20 DEG C, the casting films of extrusion flow through the first slab roller 3 and the second slab roller 4 it
Between space, cast the sheet that thickness is 400 μm；
Step 3), longitudinal stretching: the temperature difference of pre-hot-rolling, draw roll, chill roll is set
Being 80 DEG C, 110 DEG C and 20 DEG C, the most preheated roller of sheet, draw roll and chill roll are carried out
Longitudinal stretching, obtains thin film, and ratio of elongation is 6；
Step 4), cross directional stretch for the first time: arrange the first preheating zone, the first drawing zone,
The temperature of one cooling zone is respectively 100 DEG C, 115 DEG C and 95 DEG C, and the both sides of thin film are solid with fixture
Fixed, carry out cross directional stretch through the first preheating zone, the first drawing zone and the first cooling zone successively,
Ratio of elongation is 7；
Step 5), extraction: thin film is successively through the first extractant (dichloromethane and tripotassium phosphate
Ester is by weight the mixture of 22:1 composition) and the second extractant (high purity water) immersion 6h,
Then air gun is dried；
Step 6), cross directional stretch for the second time: arrange the second preheating zone, the second drawing zone,
The temperature of two cooling zones is respectively 115 DEG C, 125 DEG C and 95 DEG C, and the both sides of thin film are solid with fixture
Fixed, carry out cross directional stretch through the second preheating zone, the second drawing zone and the second cooling zone successively,
Obtaining the lithium ion battery separator of resistance to thermal contraction, ratio of elongation is 1.2.
Embodiment 2
Following weight is included for preparing the compositions of the lithium ion battery separator of resistance to thermal contraction
The component of proportioning:
Wherein,
The number-average molecular weight of high-molecular polythene is 300,000,
The number-average molecular weight of ultra high molecular polyethylene is 1,300,000,
The mean molecule quantity of white oil is 180,
The particle diameter of nanometer magnesium chloride is 60～90nm.
Prepare the lithium ion battery separator of resistance to thermal contraction in accordance with the following methods:
Step 1), extrusion: by high-molecular polythene and magnesium chloride nano-particle mix homogeneously,
By ultra high molecular polyethylene, 3,5-di-t-butyl-4-hydroxy-methylbenzene, 4-benzoyloxy
-2,2,6,6-tetramethyl piperidines, octadecyl quaternary ammonium sodium and lauric acid mix homogeneously, above-mentioned two
Plant mixture and added heat fusing by two polyethylene composition charging apertures input extruders respectively,
Put into white oil in extrusion direction by two pore former charging apertures by several times, extrude casting films, squeeze
Going out temperature is 210～240 DEG C, and rate of extrusion is 1200g/min；
Step 2), slab: shaggy first slab roller 3 and the second slab roller 4 is set
Temperature be 20 DEG C, the surface roughness of the first slab roller 3 is 0.1, the second slab roller 4
Surface roughness be 0.2, the casting films of extrusion flows through the first slab roller 3 and the second slab roller
Space between 4, casts the sheet that thickness is 400 μm；
Step 3), longitudinal stretching: the temperature difference of pre-hot-rolling, draw roll, chill roll is set
Being 80 DEG C, 110 DEG C and 20 DEG C, the most preheated roller of sheet, draw roll and chill roll are carried out
Longitudinal stretching, obtains thin film, and ratio of elongation is 6；
Step 4), cross directional stretch for the first time: arrange the first preheating zone, the first drawing zone,
The temperature of one cooling zone is respectively 100 DEG C, 115 DEG C and 95 DEG C, and the both sides of thin film are solid with fixture
Fixed, carry out cross directional stretch through the first preheating zone, the first drawing zone and the first cooling zone successively,
Ratio of elongation is 7；
Step 5), extraction: thin film is successively through the first extractant (dichloromethane and tripotassium phosphate
Ester is by weight the mixture of 22:1 composition) and the second extractant (high purity water) immersion 6h,
Then air gun is dried；
Step 6), cross directional stretch for the second time: arrange the second preheating zone, the second drawing zone,
The temperature of two cooling zones is respectively 115 DEG C, 125 DEG C and 95 DEG C, and the both sides of thin film are solid with fixture
Fixed, carry out cross directional stretch through the second preheating zone, the second drawing zone and the second cooling zone successively,
Obtaining the lithium ion battery separator of resistance to thermal contraction, ratio of elongation is 1.2.
Embodiment 3
The present embodiment method therefor is similar to embodiment 2 method therefor, differs only in: use
Compositions in the lithium ion battery separator preparing resistance to thermal contraction includes following weight proportion
Component:
Wherein,
The number-average molecular weight of high-molecular polythene is 400,000,
The number-average molecular weight of ultra high molecular polyethylene is 1,400,000.
Comparative example
Comparative example 1
This comparative example method therefor is similar to embodiment 1 method therefor, differs only in:
Step 5), extraction: thin film is successively through the first extractant (dichloromethane) and the second extraction
Taking agent (high purity water) and soak 6h, then air gun is dried.
Comparative example 2
This comparative example method therefor is similar to embodiment 1 method therefor, differs only in:
Step 5), extraction: (press with trimethyl phosphate by dichloromethane through the first extractant for thin film
The mixture of weight ratio 22:1 composition) soak 6h, then air gun is dried.
Comparative example 3
This comparative example method therefor is similar to embodiment 1 method therefor, differs only in:
Step 5), extraction: thin film soaks 6h, then gas through the second extractant (high purity water)
Rifle is dried.
Comparative example 4
Use the preparation of battery diaphragm described in embodiment 6 in patent CN201210454073.9
Method, it may be assumed that the polyethylene that number-average molecular weight is 800,000 g/mol is heated to 180 DEG C and melts,
Add in double screw extruder with 54kg/h feed rate.White oil is heated to 95 DEG C, with 2,6-
Di-tert-butyl-4-methy phenol mix and blend 3h, injects mixture twin screw at twice and squeezes
Go out in machine.Temperature within extruder is 200 DEG C, and extrusion temperature is 190 DEG C, extruded material
The sheet that thickness is 1.4mm is cast in space extruding between 15 DEG C of chill rolls and adjustable roller.
Polyethylene is 1:2.4 with the mass ratio of white oil, and the quality of 2,6-di-tert-butyl-4-methy phenols is
The 1.0% of white oil quality.
Sheet obtained above is carried out successively longitudinal stretching and first time cross directional stretch, longitudinally
The temperature of stretching is 100 DEG C, and stretching ratio is 5.78, and the temperature of cross directional stretch is for the first time
120 DEG C, stretching ratio is 4.41, after dichloromethane extracts, obtains medial septum.
Medial septum obtained above is carried out second time cross directional stretch, for the second time cross directional stretch
Temperature be 132 DEG C, stretching ratio is 1.6, and rolling is cut, 50 DEG C of Ageing Treatment 18h,
To battery diaphragm.
Experimental example
The battery diaphragm preparing embodiment and comparative example is tested as follows, and test result is shown in
Table 1:
(1) thickness of battery diaphragm is measured；
(2) use electronic scanner microscope to observe the microcellular structure of battery diaphragm, and measure
Aperture；
(3) press pump instrument is used to measure the porosity of battery diaphragm；
(4) venting quality tester is used to measure the venting quality of battery diaphragm；
(5) tension tester is used to measure the longitudinal tensile strength of battery diaphragm and laterally draw
Stretch intensity；
(6) electronic tensile machine is used to measure the puncture strength of battery diaphragm, longitudinal extension rate
With horizontal expansion rate；
(7) the longitudinally heat using battery diaphragm percent thermal shrinkage tester to measure battery diaphragm is received
Shrinkage and horizontal percent thermal shrinkage；
(8) battery septum closed pore temperature and broken film temperature tester is used to measure battery diaphragm
Closed pore temperature and broken film temperature.
Table 1. battery diaphragm test result
Above in association with preferred implementation, embodiment and comparative example, the present invention is carried out in detail
Explanation.But it is to be understood that, these detailed description of the invention are only the elaborations to the present invention
Property explain, not to protection scope of the present invention constitute any restriction.Without departing from the present invention
In the case of spirit and scope, the technology of the present invention content and embodiment thereof can be entered
The various improvement of row, equivalencing or modification, these each fall within protection scope of the present invention.
Protection scope of the present invention is as the criterion with claims.
Claims (8)
1. the extractant group being used for preparing the lithium ion battery separator of resistance to thermal contraction
Compound, it is characterised in that said composition includes the first extractant and the second extractant,
Wherein,
Described first extractant is the mixture of dichloromethane and phosphate ester composition,
Described second extractant is water.
Extractant composition the most according to claim 1, it is characterised in that institute
Stating phosphate ester is one or more in trimethyl phosphate or triethyl phosphate.
Extractant composition the most according to claim 1 and 2, it is characterised in that
Described dichloromethane is 10:1～40:1 with the weight ratio of phosphate ester, is preferably
15:1～30:1.
4., according to the extractant composition one of claims 1 to 3 Suo Shu, its feature exists
In, described second extractant is high purity water.
5. a preparation method for the lithium ion battery separator of resistance to thermal contraction, its feature exists
In, the method includes:
Step 1), polyethylene or a combination thereof thing, pore former and optional additive are melted
Melt mixing, extrude casting films；
Step 2), step 1) casting films extruded flows through the first slab roller (3) and
Space between two slab rollers (4), casts sheet；
Step 3), step 2) the most preheated roller of sheet, draw roll and the cooling that obtain
Roller carries out longitudinal stretching, obtains thin film；
Step 4), step 3) the thin film both sides that obtain fix, successively through the first preheating zone,
First drawing zone and the first cooling zone carry out cross directional stretch；
Step 5), step 4) thin film that obtains is through according to one of Claims 1-4 Suo Shu
Extractant composition process, be then dried；
Step 6), step 5) the thin film both sides that obtain fix, successively through the second preheating zone,
Second drawing zone and the second cooling zone carry out cross directional stretch, obtain the lithium of resistance to thermal contraction from
Sub-battery diaphragm.
Preparation method the most according to claim 5, it is characterised in that in step 5)
In,
Described process is to soak with extractant, and/or
Described being dried in drying device is carried out, and described drying device includes multiple one-tenth folding
The transfer roller (6) of line arrangement, is arranged in the position that thin film contacts with transfer roller (6)
Having for dry air gun (7), the jet direction of the most described air gun (7) is with described
The plane tangent of transfer roller (7) or parallel with the direction of transfer of thin film.
7. the lithium ion of the resistance to thermal contraction prepared according to method described in claim 5 or 6
Battery diaphragm, it is characterised in that this barrier film includes the first outer layer (9), the second outer layer
(10) and be clipped in internal layer (11) therebetween, described first outer layer (9), second
Outer layer (10) and internal layer (11) have different microcellular structures,
The average pore size of the most described first outer layer (9) is 20～100nm, outside second
The average pore size of layer (10) is 30～140nm, and the aperture of internal layer (11) is 50～180
nm。
Battery diaphragm the most according to claim 7, it is characterised in that
The thickness of described barrier film is 5～25 μm, and/or
Porosity is 40～90%, and/or
Venting quality is 200～400sec/100ml, and/or
Longitudinal tensile strength is 1800～2200kgf/cm2, and/or
Transverse tensile strength is 1800～2500kgf/cm2, and/or
Puncture strength is 600～1000gf, and/or
Longitudinal extension rate is 160～220%, and/or
Horizontal expansion rate is 150～210%, and/or
Longitudinal percent thermal shrinkage is not more than 0.5%, and/or
Laterally percent thermal shrinkage is not more than 0.3%, and/or
Closed pore temperature is 120～150 DEG C, and/or
Broken film temperature is 160～180 DEG C.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109065807A (en) * | 2018-08-01 | 2018-12-21 | 河北金力新能源科技股份有限公司 | A kind of oiliness PVDF coating, its preparation process and its coating method for lithium ion battery separator |
| WO2019140780A1 (en) * | 2018-01-16 | 2019-07-25 | 溧阳月泉电能源有限公司 | Method and system for manufacturing separator membrane of secondary lithium-ion battery |
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