CN106328866A - Preparation method for battery diaphragm with three kinds of microporous structures - Google Patents
Preparation method for battery diaphragm with three kinds of microporous structures Download PDFInfo
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- CN106328866A CN106328866A CN201510346563.0A CN201510346563A CN106328866A CN 106328866 A CN106328866 A CN 106328866A CN 201510346563 A CN201510346563 A CN 201510346563A CN 106328866 A CN106328866 A CN 106328866A
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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
- H01M50/411—Organic material
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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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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/10—Batteries in stationary systems, e.g. emergency power source in plant
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
-
- 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 preparation method for a battery diaphragm with three kinds of microporous structures. The preparation method comprises the steps of performing fusing and mixing on a polyethylene composition, a pore-forming agent and an optional additive; extruding a cast film, and casting a thick sheet through a first sheet-casting roller and a second sheet-casting roller; next, performing longitudinal stretching through a preheating roller, a stretching roller, and a cooling roller; performing transverse stretching for the first time by passing through a first preheating region, a first stretching region and a first cooling region; performing extracting and pore-forming, and drying; and performing transverse stretching for the second time by passing through a second preheating region, a second stretching region and a second cooling region to obtain the battery diaphragm with the three kinds of microporous structures. The preparation method for the battery diaphragm with the three kinds of microporous structures is simple and convenient to operate, high in controllability and wide in application; and the battery diaphragm prepared by the method is good in comprehensive performance.
Description
Technical field
The present invention relates to the preparation technology of battery diaphragm, be specifically related to three kinds of microcellular structures
The preparation method of battery diaphragm.
Background technology
Lithium ion battery is widely used in the fields such as telecommunications, energy storage and electrical source of power,
Mainly it is made up of positive pole, negative pole, electrolyte and battery diaphragm, wherein, battery diaphragm
It is nonconducting, between positive pole and negative pole, prevents the two short circuit because of contact,
Allowing electrolyte ion to pass through simultaneously, thus produce electric current, current battery diaphragm is many
For having the polyethylene composition film of microcellular structure, its performance determines the interface of battery
Structure, internal resistance etc., directly affect the spies such as the capacity of battery, circulation and security performance
Property, the battery diaphragm of excellent performance has important function to the combination property improving battery.
The performance of battery diaphragm mainly characterizes by following index: the property cut off requires battery
Barrier film has partition property and electronic isolation, it is ensured that effective mechanical isolation of positive and negative electrode；
Porosity requires that barrier film has certain aperture and porosity, it is ensured that low resistance and height
Ionic mobility, lithium ion is had good permeability；Chemical stability and electricity are steady
Qualitative requirement barrier film possesses moisture-proof and electrolyte resistance corrosivity；Wellability requires barrier film
Good to the wellability of electrolyte, and there is preferable imbibition moisture-retaining capacity and ion is penetrating
Property；Mechanical strength requires that barrier film to ensure enough power while thickness is the least
Learn performance and shock resistance, including puncture strength and hot strength；Security requirement barrier film
Heat stability to be had and automatically shut down protective value, including closed pore temperature and rupture of membranes temperature
Degree.It is to be mutually related between the multinomial performance index of battery diaphragm, it is desirable to take into account multinomial
Performance, obtain indices all preferably battery diaphragm the most still there is bigger difficulty.
Existing polyethylene composition battery diaphragm preparation method is broadly divided into wet method and does
Method, wherein the preparation process of wet method includes: added as pore former by little for high boiling point molecule
Being added in polyethylene composition, heating is melt into homogeneous system, and then cooling occurs phase
Separate, after biaxial tension, extract little molecule with organic solvent, can prepare mutually
Through micro-pore septum.
There are some defects in traditional battery diaphragm wet method preparation process, including: in casting
A slab roller with refrigerating function is generally used to carry out one side cooling during sheet,
Pore former is closed not exclusively, easily flows out, causes micropore skewness；Different productions
Extrusion equipment in step is different, causes product quality pattern different, is difficult to control one
Cause property；Generally extrusion equipment, stretcher roller smooth surface, the barrier film table produced
Face is smooth, poor with the adhesive power of other material, is unfavorable for researching and developing novel battery barrier film；
After extraction, drying equipment generally uses hydraulic giant and air gun two ways to carry out simultaneously, causes
Generally there is water wave on the surface of barrier film, and flatness is the best.
Above-mentioned condition based on prior art, the present inventor's preparation work to battery diaphragm
Skill is studied, it is therefore an objective to provide the good three kinds of microcellular structure batteries of combination property every
The preparation method of film.
Summary of the invention
In order to overcome the problems referred to above, the preparation method of battery diaphragm is carried out by the present inventor
Study with keen determination, found that: by use specific proportioning high-molecular polythene and
Ultra high molecular polyethylene is raw material, selects and adds suitable pore former and/or interpolation
Agent, after specific device and processing technique, can obtain having relatively low closed pore temperature, relatively
High broken film temperature and good mechanical strength and the good battery diaphragm of thermal shrinkage, thus
Complete the present invention.
Therefore, it is an object of the invention to provide the system of three kinds of microcellular structure battery diaphragms
Preparation Method, the method includes:
Step 1), extrusion: by polyethylene composition, 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 He
Space between second slab roller 4, casts sheet；
Step 3), longitudinal stretching: step 2) obtain the most preheated roller of sheet, draw
Stretch roller and chill roll carries 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,
Cross directional stretch is carried out successively through the first preheating zone, the first drawing zone and the first cooling zone；
Step 5), extraction: step 4) thin film that obtains processes through extractant, then does
Dry；
Step 6), cross directional stretch for the second time: step 5) the thin film both sides that obtain fix,
Cross directional stretch is carried out successively through the second preheating zone, the second drawing zone and the second cooling zone,
Obtain the battery diaphragm of three kinds of microcellular structures.
Another object of the present invention also resides in the offer above-mentioned preparation method of one enforcement and is used
Device, it includes extrusion device, cooling roller device and drying device, wherein,
Described extrusion device includes machine barrel, is disposed in parallel in two of described machine barrel one end
Polyethylene composition charging aperture 1 and being respectively arranged on described machine barrel away from described polyethylene
Compositions charging aperture 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 He that spacing is 180～580 μm
Second slab roller 4, the diameter ratio of described first slab roller 3 and the second slab roller 4 is 1:
(1～6), described first slab roller 3 and the second slab roller 4 rotate in opposite directions, it is preferable that
The roller linear velocity of described first slab roller 3 and the roller linear speed of described second slab roller 4
Number of degrees value is equal,
Described drying device includes the transfer roller 6 that multiple one-tenth broken line is arranged, in thin film and biography
The position sending roller 6 to contact is provided with for dry air gun 7, the most described air gun 7
Jet direction and described transfer roller 6 plane tangent or with the direction of transfer phase of thin film
Parallel.
The present invention described below.
According to the present invention, it is provided that the preparation method of three kinds of microcellular structure battery diaphragms, should
Method comprises the following steps:
Step 1), extrusion: by polyethylene composition, pore former and optional additive
Melting mixing, extrudes casting films.
In a preferred embodiment in accordance with the present invention, described polyethylene composition includes
88～92 weight portion high-molecular polythenes and 8～12 weight portion ultra high molecular polyethylenes, excellent
Choosing includes 89～91 weight portion high-molecular polythenes and the 9～11 poly-second of weight portion supra polymer
Alkene, more preferably includes that 90 weight portion high-molecular polythenes and 10 weight portion supra polymers gather
Ethylene.
Wherein, the number-average molecular weight of described high-molecular polythene is 100,000～600,000, excellent
Elect 200,000～500,000 as, more preferably 300,000～400,000, described ultra high molecular polyethylene
Number-average molecular weight is 1,200,000～1,500,000, preferably 1,300,000～1,400,000.
In a preferred embodiment in accordance with the present invention, described pore former includes organic one-tenth
Hole agent and Inorganic pore forming agents.
Described organic pore former is preferably mineral oil, C6-15Alkane, C8-15Aliphatic carboxylic acid,
C1-4Alkyl ester, C2-6One or more in halogenated alkane, described mineral oil is preferably white
Oil, described C6-15Alkane is selected from heptane, naphthalane, decane, hendecane and dodecane,
Described C8-15Aliphatic carboxylic acid is selected from capric acid, hendecoic acid and lauric acid, described C1-4
Alkyl ester selected from methyl caprate, ethyl caprate, capric acid propyl ester, capric acid N-butyl, 11
Methyl carbonate, hendecoic acid ethyl ester, hendecoic acid propyl ester, hendecoic acid N-butyl,
Lauric acid methyl ester, dodecanoate, lauric acid propyl ester, the positive fourth of lauric acid
Ester, described C2-6Halogenated alkane selected from dichloroethanes, dichloropropane, chlorofluoroethane and
Fluorine chloropropane, described organic pore former more preferably mineral oil is the whitest
Oil.
Described Inorganic pore forming agents is preferably the nano-particle of water-soluble inorganic salt, described water
The nano-particle of soluble inorganic salt is selected from water soluble sulfate, water-soluble nitrate, water
One or more in soluble silicate nanometer granule, described water soluble sulfate is selected from
Sodium sulfate, potassium sulfate and ammonium sulfate etc., described water-soluble nitrate selected from sodium nitrate,
Potassium nitrate, ammonium nitrate, magnesium nitrate and copper nitrate etc., described water-soluble hydrochloride salt is selected from
Sodium chloride, potassium chloride, ammonium chloride, magnesium chloride, calcium chloride and copper chloride etc., described
Inorganic pore forming agents more preferably magnesium chloride nano-particle, the grain of described nano-particle
Footpath is 5～200nm, preferably 8～100nm, more preferably 10～50nm, compared to
Liquid or the organic pore former of oily, the Inorganic pore forming agents of described solid granular has
Bigger particle diameter and fixing form, thus there is higher occupy-place effect, can be at electricity
Form the microcellular structure that aperture is bigger in the barrier film of pond, can better control over and form micropore
Size, shape and distribution, and be conducive to improving porosity and the air permeability of battery diaphragm,
As: can be different by selecting the Inorganic pore forming agents of different-grain diameter to prepare micropore size
Battery diaphragm.The addition of described organic pore former is polyethylene composition weight
30～60%, the addition of described Inorganic pore forming agents is polyethylene composition weight
1～10%.
Described additive preferably includes antioxidant, anti ultraviolet agent, antistatic additive and prevents
One or more in mist agent, 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
Butylated hydroxytoluene, tert-butyl hydroquinone, preferably 4,4-thiobis (the 6-tert-butyl group
Metacresol)；
Described anti ultraviolet agent is selected from salicylic acid esters, benzophenone class, benzotriazole, takes
For vinyl cyanide, triazines and hindered amines, preferably oxybenzoic acid phenyl ester,
2-(2-hydroxyl-5-aminomethyl phenyl) BTA, 2,4-DihydroxyBenzophenone,
ESCALOL 567, Octabenzone, 2-(2'-
The tertiary phenyl of hydroxyl-3', 5'-bis-)-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
With HMPA etc.；
Described antistatic additive is selected from cationic antistatic agent, anionic antistatic agents and non-
Ionic antistatic agent, is preferably selected from quaternary ammonium salt, ethoxy alkylation aliphatic alkylamine
Class, such as octadecyl quaternary ammonium sodium；
Described antifoggant selected from the ester of xylitol, sorbitol palmitate, lauric acid,
Span series, TWEEN Series surfactant or animi resin acid glycerol list
Ester, preferably span series and TWEEN Series surfactant.
In a preferred embodiment in accordance with the present invention, described melting mixing extruding
Process is carried out in extruder or extrusion device, and described extruder or extrusion device include
Machine barrel, be disposed in parallel in described machine barrel one end two polyethylene composition charging apertures and
Be respectively arranged on described machine barrel away from described polyethylene composition charging aperture be 1/3 and 2/3
Two pore former charging apertures at barrel length.
Polyethylene composition, Inorganic pore forming agents and optional additive are pre-mixed all
Put into extruder after even, preferably Inorganic pore forming agents is pre-mixed with high-molecular polythene
Uniformly, optional additive and ultra high molecular polyethylene are pre-mixed uniformly, put into
Extruder, then add heat fusing, at the polyethylene composition of extruder inner molten
Extrusion adds organic pore former on direction, and described organic pore former is preferably dividedly in some parts crowded
Go out machine, extrude casting films after melted also mix homogeneously, use above-mentioned preferred mode to add
Enter described Inorganic pore forming agents and organic pore former, polyethylene composition and pore-forming can be avoided
Being separated and causing mixing inequality and with pressure oscillation in extruder occur in agent so that
Polyethylene composition and pore former are sufficiently mixed uniformly, and pore former is uniformly distributed in poly-second
In ene compositions mixture, beneficially subsequent step prepares micropore aperture and
The battery diaphragm being more evenly distributed.
In a preferred embodiment in accordance with the present invention, described polyethylene composition, one-tenth
Hole agent and optional additive can first mix, and are again heated to molten condition, it is also possible to
Adding heat fusing the most respectively, then mixed by melted above-mentioned substance, the present invention is excellent
Described polyethylene composition, pore former and optional additive are first mixed all by choosing respectively
Even, add and extruder is heated to molten condition and stirs 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 rate of extrusion are straight
Connect and affect step 2) in prepare the character of sheet and thickness, and determine finally to prepare every
Every physicochemical property of film.Extrusion temperature is the highest, and the mobility of casting films is the best, point
Sub-confusion degree is the highest, and the crystallinity preparing barrier film is the poorest；Extrusion temperature is the lowest, stream
The mobility prolonging film is the poorest, and molecule confusion degree is the lowest, and degree of molecular orientation is the highest, system
The crystallinity obtaining barrier film is the best, and in the present invention, extrusion temperature is 150～250 DEG C, is preferably
170～240 DEG C.Rate of extrusion is too fast, and casting films is at the first slab roller and the second slab roller
Between pile up too much, be likely to result in Local cooling hardening and affect slab and carry out；Extrusion
Speed is the slowest, is likely to result in prepared slab thicknesses uneven or the thinnest, squeezes in the present invention
Going out speed is 800～2000g/min, preferably 1000～1500g/min.
Step 2), slab: step 1) casting films extruded flows through the first slab roller and
Space between two slab rollers, casts sheet.
In a preferred embodiment in accordance with the present invention, described slab process is at chill roll
Carrying out in device, described cooling roller device includes the first casting that spacing is 180～580 μm
Sheet roller and the second slab roller, the diameter ratio of described first slab roller and the second slab roller is
1:(1～6), described first slab roller and the second slab roller rotate in opposite directions, it is preferable that
The roller linear velocity of described first slab roller and the roller linear velocity of described second slab roller
Numerical value is equal.
Described first slab roller and the second slab roller opposite direction rotating, squeeze from extruder die head
The casting films gone out forms accumulation, then warp between the first slab roller and the second slab roller
Cross space extruding therebetween, cooling, cast sheet, reduce rate of extrusion not
All, the factor impact on sheet character such as extruder machinery concussion, thus prepare thickness
The sheet that degree is uniformly, character is stable.
In a preferred embodiment in accordance with the present invention, described first slab roller and second
The temperature of slab roller is 5～40 DEG C, preferably 10～35 DEG C, more preferably 12～33 DEG C,
The casting films of extrusion flows through during the space between the first slab roller and the second slab roller two-sided
Cooling molding, casts sheet, meanwhile, is uniformly distributed pore former therein with poly-
There is thermotropic being separated in vinyl composition, pore former is closed by the sheet of two-sided cooling
Therein, compared with the sheet of one side cooling in traditional handicraft, pore former is less susceptible to
Ooze out, be conducive to preparing the more uniform battery diaphragm of the aperture of micropore, distribution.
In a preferred embodiment in accordance with the present invention, optionally by described first slab roller
Or second the surface of slab roller be processed into rough plane, single or double can be prepared
Coarse battery diaphragm, improves membrane surface to other material (such as: coating, film
Etc.) adhesive power, for research and development novel battery barrier film lay a good foundation.
In a preferred embodiment in accordance with the present invention, the direct shadow of the thickness of described sheet
Ringing the final thickness preparing barrier film, in general, sheet is the thickest, and the barrier film prepared is more
Thickness, can adjust by regulating the gap length between the first slab roller and the second slab roller
The thickness of joint sheet, the thickness of heretofore described sheet is 200～600 μm, preferably
It is 250～550 μm, more preferably 300～500 μm.
Step 3), longitudinal stretching: step 2) obtain the most preheated roller of sheet, draw
Stretch roller and chill roll carries out longitudinal stretching.
In a preferred embodiment in accordance with the present invention, the most preheated roller of described sheet
Preheat with lower temperature, soften sheet, prepare for stretching, prevent sheet because of suddenly
High-temperature heating and cause character cataclysm；Then, described sheet gradually rises through multiple rotating speeds
High draw roll at high temperature carries out longitudinal stretching；Finally, cooled roller sub-cooled
Sizing, obtains the thin film that character is fixing.After longitudinal stretching, thin film is compared with sheet
Elongate in the vertical, lower thickness, and longitudinal mechanical strength is improved, meanwhile,
The micropore longitudinally elongated one-tenth elongate of its internal pore former occupy-place.
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,
Prepare for stretching；
The temperature of described draw roll is 70～150 DEG C, preferably 80～140 DEG C, more preferably
It is 90～130 DEG C, while ensureing the good tensile property of sheet, makes pore former occupy-place
Micropore 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 so that the rapid cooling and shaping of thin film after drawing by high temperature, keep longitudinal stretching
After length, thickness and aperture.
In a preferred embodiment in accordance with the present invention, the rotating speed of the plurality of draw roll
In the range of 2～40m/min, gradient raises so that stretching uniformly, is stretched by regulation
The rotating speed of roller 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,
Cross directional stretch is carried out successively 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 of described thin film are pressed from both sides
Tool is fixing, first passes around the first preheating zone and preheats, and softens thin film, does for stretching
Prepare；Then, cross directional stretch, symmetrical folder are at high temperature carried out through the first drawing zone
Tool spacing is gradually increased；Finally, through the first cooling zone sub-cooled sizing, obtain
The thin film that character is fixing.After first time cross directional stretch, thin film elongates in the horizontal,
Lower thickness, and laterally mechanical strength is improved, meanwhile, its internal pore former accounts for
The micropore horizontal elongation of position becomes similar circle.
In a preferred embodiment in accordance with the present invention, the temperature of described first preheating zone
It is 60～150 DEG C, preferably 70～140 DEG C, more preferably 75～135 DEG C, preheated film,
Prepare for stretching；
The temperature of described first drawing zone is 80～150 DEG C, preferably 85～145 DEG C, more
It is preferably 90～140 DEG C, while ensureing the good tensile property of thin film, makes pore former
The micropore of occupy-place reaches suitable aperture；
The temperature of described first cooling zone is 60～150 DEG C, preferably 70～140 DEG C, more
It is preferably 75～135 DEG C so that the rapid cooling and shaping of thin film after drawing by high temperature, keeps
Length, thickness and aperture after cross directional stretch for the first time.
In a preferred embodiment in accordance with the present invention, described thin film is the most at the uniform velocity
Mobile, the cross directional stretch degree of thin film is regulated 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, preferably 3.5～10.5,
More preferably 4～10, obtain that there is the thin of suitable thickness, aperture and horizontal mechanical strength
Film.
Step 5), extraction: step 4) thin film that obtains processes through extractant, then does
Dry.
In a preferred embodiment in accordance with the present invention, described extractant preferably includes
One extractant and the second extractant, step 4) thin film that obtains is successively through the first extraction
Agent and the second extractant immersion treatment.
In a preferred embodiment in accordance with the present invention, the most at twice pore former is entered
Row extraction, first extracts the organic pore former component in pore former with the first extractant,
The Inorganic pore forming agents component in pore former is extracted again with the second extractant.By the first extraction
When taking agent and the second extractant immersion thin film, it is evenly distributed on the pore former within thin film
Dissolved extraction, and forms microcellular structure, micropore in the position originally occupied by pore former
Distribution and aperture whether uniformly and pore creating material be distributed in thin film the most dispersed directly
Connect relevant；Described first extractant is to dissolve the organic pore former component in pore former
Property good, and the polyethylene composition in insoluble thin film and the reagent of additive, this
The bright mixture preferably selecting dichloromethane and phosphate ester composition, described phosphate ester is excellent
Elect one or more in trimethyl phosphate and triethyl phosphate, wherein, dichloromethane as
Alkane is 10:1～40:1, preferably 15:1～30:1 with the weight ratio of phosphate ester, described first
Extractant is better than simple dichloromethane to the effect of extracting of organic pore former, and extraction is more
Completely, pore former residual is few；Described second extractant is to the inorganic one-tenth in pore former
Agent component dissolubility in hole is good, and the polyethylene composition in insoluble thin film and additive
Reagent, the present invention preferably selects water, more preferably high purity water.
Drying device is dried.Described drying device includes that multiple one-tenth broken line is arranged
The transfer roller of cloth.In a preferred embodiment in accordance with the present invention, in thin film and transmission
The position that roller contacts is provided with for dry air gun, the jet of the most described air gun
Direction and the plane tangent of described transfer roller or parallel with the direction of transfer of thin film.
Use air gun that the thin film after extraction is dried, to remove film surface residual
Extractant, prevent stain mark, described air gun drying effect is good, and effectively keeps away
Exempt from the generation of film surface water ripples, meanwhile, by Reasonable adjustment air gun and thin film
Position so that the vertical impact forces of thin film is obviously reduced by air gun, significantly improves
The bad phenomenon such as final prepared battery diaphragm outward appearance fold, scollop, scallop.
Step 6), cross directional stretch for the second time: step 5) the thin film both sides that obtain fix,
Cross directional stretch is carried out successively through the second preheating zone, the second drawing zone and the second cooling zone,
Obtain the battery diaphragm of three kinds of microcellular structures.
In a preferred embodiment in accordance with the present invention, the both sides of described thin film are pressed from both sides
Tool is fixing, first passes around the second preheating zone and preheats, and softens thin film, does for stretching
Prepare；Then, at high temperature carry out small size cross directional stretch through the second drawing zone, symmetrical
Spacing jig from being gradually increased；Finally, through the second cooling zone sub-cooled sizing,
Obtain the battery diaphragm of three kinds of fixing microcellular structures of character.For the second time cross directional stretch with
Cross directional stretch is compared for the first time, and level of stretch substantially reduces, through second time cross directional stretch
After, the thin film with microcellular structure the most slightly elongates or keeps constant, passes through
Heating-cooling process makes its mechanical strength, air permeability, thermal contraction performance improve further,
Meanwhile, its internal micropore horizontal elongation, aperture increases, obtains having good character
The battery diaphragm of three kinds of microcellular structures.
In a preferred embodiment in accordance with the present invention, the temperature of described second preheating zone
It is 70～160 DEG C, preferably 80～150 DEG C, more preferably 90～140 DEG C, preheated film,
Prepare for stretching；
The temperature of described second drawing zone is 100～155 DEG C, preferably 105～150 DEG C,
More preferably 110～145 DEG C, while ensureing the good tensile property of thin film, make micropore
Reach suitable aperture；
The temperature of described second cooling zone is 60～130 DEG C, preferably 65～135 DEG C, more
It is preferably 70～130 DEG C so that the rapid cooling and shaping of thin film after drawing by high temperature, keeps
Length, thickness and aperture after cross directional stretch for the second time.
In a preferred embodiment in accordance with the present invention, described thin film is the most at the uniform velocity
Mobile, the cross directional stretch degree of thin film is regulated 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
It is preferably 0.8～3, obtains that there is suitable thickness, aperture, mechanical strength and heat-shrinkable
The battery diaphragm of three kinds of microcellular structures of energy.
In a preferred embodiment in accordance with the present invention, step 6) battery diaphragm that obtains
Including the first outer layer, the second outer layer be clipped in internal layer therebetween, outside described first
Layer, the second outer layer and internal layer have different microcellular structures.
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
50～180nm.
To be mutually related between the multinomial performance index of battery diaphragm, thickness less every
Film tends to stretch out intensity and puncture strength is relatively low, the most damaged in battery installation process；
The general fusing point of polyethylene composition material that the barrier film that mechanical strength is higher uses is higher,
Therefore closed pore temperature is higher, poor stability, although can change the raw materials for production of barrier film
Or working condition significantly improves some performance indications, but want to take into account multinomial performance,
Obtain indices all preferably battery diaphragm and the most still there is bigger difficulty.
The present invention is by adding superelevation in battery diaphragm raw materials for production high-molecular polythene
Molecular polyethylene, to improve the mechanical strength of battery diaphragm, can prepare and have excellent machine
The thinner battery diaphragm of tool intensity, meanwhile, polyphosphazene polymer second in strict control raw material
Alkene and the proportioning of ultra high molecular polyethylene so that prepared battery diaphragm still has relatively
Low closed pore temperature and higher broken film temperature, it addition, by selecting and adding properly
Pore former and/or additive, use specific device and processing technique, prepare have good
The battery diaphragm of three kinds of microcellular structures of good combination property.
In a preferred embodiment in accordance with the present invention, the performance of described battery diaphragm is such as
Under:
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, preferably 220～380sec/100ml,
More preferably 250～350sec/100ml；
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
660～900gf；
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 3%, and preferably no greater than 2.8%, more preferably no more than
2.5%；
Laterally percent thermal shrinkage is not more than 1%, and preferably no greater than 0.5%, 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 is while thickness is relatively low
There is higher hot strength and puncture strength, can be used for preparing the battery that volume is less,
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；
And percent thermal shrinkage is low, reduce during the use of battery because of barrier film heat shrinkable
Cause the problems such as battery open circuit；Meanwhile, there is relatively low closed pore temperature and higher breaking
Film temperature, safety is high.
According to the present invention, the preparation method of three kinds of microcellular structure battery diaphragms 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 of described machine barrel one end
Polyethylene composition charging aperture and being respectively arranged on described machine barrel away from described polyethylene group
Compound charging aperture is two pore former charging apertures at 1/3 and 2/3 barrel length.
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),
Described first slab roller and the second slab roller rotate in opposite directions, it is preferable that described first casting
The roller linear velocity of sheet roller and the roller linear velocity numerical value of described second slab roller 4 are equal.
Described drying device includes the transfer roller that multiple one-tenth broken line is arranged, in thin film and biography
The position sending roller to contact is provided with for dry air gun, the spray of the most described air gun
Gas direction and 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) preparation method of three kinds of microcellular structure battery diaphragms that the present invention provides uses
The high-molecular polythene of specific proportioning and ultra high molecular polyethylene are raw material, select and add
Add suitable pore former and/or additive, after specific device and processing technique, prepare
The battery diaphragm of described three kinds of microcellular structures so that this barrier film has relatively low closed pore temperature
Degree, higher broken film temperature and good mechanical strength and good thermal shrinkage；
(2) preparation method of three kinds of microcellular structure battery diaphragms that the present invention provides is being squeezed
During going out, Inorganic pore forming agents is first mixed with polyethylene composition, at extrusion
Middle organic pore former is dividedly in some parts, prevents pore former and polyethylene composition generation phase
Separate and cause extruder pressure fluctuating in inner, cause rate of extrusion uneven, stable crowded
Go out casting films so that the slab thicknesses cast is uniform；
(3) preparation method of three kinds of microcellular structure battery diaphragms that the present invention provides is in casting
The while of using the first slab roller and second slab roller with refrigerating function during sheet
Carry out two-sided cooling slab, thus pore former is preferably enclosed in inside sheet, and
The slab thicknesses cast is uniform, stable；Meanwhile, optionally the surface of slab roller is processed
Become rough plane, the more preferable shaggy battery diaphragm of cohesive can be prepared, have
It is beneficial to exploitation novel battery barrier film；
(4) preparation method of three kinds of microcellular structure battery diaphragms that the present invention provides is vertical
During stretching, for the first time cross directional stretch and second time cross directional stretch, can basis
The difference of required barrier film arranges different temperature, rotating speed and other parameters, thus prepares
Different-thickness, aperture, the battery diaphragm of three kinds of microcellular structures of microporosity, operation letter
Just, controllability is strong, is widely used；
(5) preparation method of three kinds of microcellular structure battery diaphragms that the present invention provides uses
The mixture that organic pore former and Inorganic pore forming agents form in specific proportions is as pore-forming
Agent, can better control over the formation size of micropore, shape and distribution, is conducive to improving
The porosity of battery diaphragm and venting quality, extraction during the most successively on
State two kinds of pore former components to extract, use dichloromethane and phosphate ester by specific ratio
The mixture of example composition is the first extractant, is used for extracting organic pore former, uses water
As the second extractant, being used for extracting Inorganic pore forming agents, extraction is more complete, pore former
Residual is few；
(6) preparation method of three kinds of microcellular structure battery diaphragms that the present invention provides is in extraction
Changed the direction of advance of thin film into broken line by straight line during being dried after taking, and use gas
Rifle substituted for original hydraulic giant, and makes the jet direction of air gun think with thin film direction of transfer
Parallel, reach good drying effect, and effectively reduce prepared battery diaphragm table
There is the phenomenon, beneficially rolling and raising such as water ripples and outward appearance fold, scollop, scallop in face
The usability of battery diaphragm；
(7) preparation method of three kinds of microcellular structure battery diaphragms of present invention offer is provided
The battery diaphragm prepared has three-decker, and the micro-pore shape of every layer, aperture are the most not
With, micropore is evenly distributed, and porosity is high；
(8) preparation method of three kinds of microcellular structure battery diaphragms of present invention offer is provided
The battery diaphragm prepared takes into account multinomial physicochemical property, good combination property, is reaching relatively low
Possess high puncture strength and hot strength while thickness, can be applicable to less battery
And in installation process not cracky；There is good air permeability and porosity simultaneously,
Internal resistance is little, improves capacity and the cycle performance of battery；It addition, also have relatively low closing
Hole temperature and broken film temperature, 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 three kinds of microcellular structure batteries 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.By this
A little explanations, the features and advantages of the invention will become more apparent from clearly.
According to the present invention, the preparation method of three kinds of microcellular structure battery diaphragms uses specific
Device, this device includes extrusion device, cooling roller device and drying device, specifically
As follows:
Extrusion device
As it is shown in figure 1, described extrusion device includes polyethylene composition charging aperture 1 and becomes
Hole agent charging aperture 2.
In a preferred embodiment in accordance with the present invention, described extrusion device preferably includes
Two polyethylene composition charging apertures 1 and two pore former charging apertures 2.
Described extrusion device also includes machine barrel, said two polyethylene composition charging aperture 1
Being juxtaposed on one end of described machine barrel, said two pore former charging aperture 2 is respectively provided with
On described machine barrel away from described polyethylene composition charging aperture 1 be that 1/3 and 2/3 machine barrel is long
At degree.
In a preferred embodiment in accordance with the present invention, polyethylene or a combination thereof thing, nothing
Machine pore former and optional additive are pre-mixed after uniformly through said two polyethylene group
Compound charging aperture 1 adds described extrusion device, preferably by Inorganic pore forming agents and polyphosphazene polymer
Ethylene is pre-mixed uniformly, is mixed in advance with ultra high molecular polyethylene by optional additive
Closing uniformly, above two mixture is respectively through said two polyethylene composition charging aperture 1
Add described extrusion device, be more easy to mix homogeneously.
Said mixture is heated to molten condition and along described machine in described extrusion device
Cylinder extrusion, adds organic pore-forming through said two pore former charging aperture 2 in extrusion direction
Agent, extrudes casting films after melted also mix homogeneously, can avoid polyethylene composition and become
Being separated and causing mixing inequality and with pressure oscillation in extruder occur in hole agent, makes
Obtaining polyethylene composition to be sufficiently mixed uniformly with pore former, pore former is uniformly distributed in poly-
In vinyl composition mixture, subsequent step beneficially prepares the aperture of micropore
With the battery diaphragm being more evenly distributed.
Cooling roller device
As in figure 2 it is shown, described cooling roller device includes that axis is positioned in same level
First slab roller 3 and the second slab roller 4, described first slab roller 3 and the second slab roller 4
Between spacing be 180-580 μm, preferably 230-530 μm, more preferably
280-480μm。
In a preferred embodiment in accordance with the present invention, described first slab roller 3 and second
Slab roller 4 opposite direction rotating, from the casting films of extruder die head 5 extrusion at the first slab roller 3
With second formed between slab roller 4 and pile up, be then passed through space extruding therebetween,
Cooling, cast sheet, reduce rate of extrusion inequality, extruder machinery concussion etc. because of
The element impact on sheet character, 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 second
The diameter of slab 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
A diameter of 500-900mm of roller 4.
The cooling that is internally provided with at described first slab roller 3 and the second slab roller 4 fills
Put, for controlling the first slab roller 3 and temperature on the second slab roller 4 surface, thus right
The casting films of extrusion cools down, the most described first slab roller 3 and the second slab roller 4
Temperature be 5～40 DEG C, preferably 10～35 DEG C, more preferably 12～33 DEG C, extrusion
Two-sided cooling when casting films flows through the space between the first slab roller 3 and the second slab roller 4
Molding, casts sheet, meanwhile, is uniformly distributed pore former therein and polyethylene
There is thermotropic being separated in compositions, pore former is enclosed in it by the sheet of two-sided cooling
Inside, compared with the sheet of one side cooling in traditional handicraft, pore former is less susceptible to ooze out,
Be conducive to preparing the more uniform battery diaphragm of the aperture of micropore, distribution.
In a preferred embodiment in accordance with the present invention, optionally by described first slab roller 3
Or second the surface of slab roller 4 be processed into rough plane, single or double can be prepared
Coarse battery diaphragm, improves membrane surface to other material (such as: coating, film
Etc.) adhesive power, for research and development novel battery barrier film lay a good foundation.
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,
It is provided with for dry air gun 7 in the position that thin film contacts with transfer roller 6.
In a preferred embodiment in accordance with the present invention, the jet direction of described air gun 7 with
The plane tangent of described 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 biographies
Sending roller 6 to advance along broken line, the position contacted with each transfer roller 6 at thin film is provided with
For dry air gun 7, to remove the extractant of film surface residual, prevent stain
Mark, the jet direction of described air gun 7 and the plane tangent of transfer roller, i.e. with the biography of thin film
Sending direction parallel, drying effect is good, and effectively prevent film surface water ripples
Generation, meanwhile, the vertical impact forces of thin film is obviously reduced by air gun 7, significantly improves
Final prepare the bad phenomenon such as battery diaphragm outward appearance fold, scollop, scallop.
Different from foregoing of the present invention, in traditional processing technology, as shown in Figure 4,
Thin film after extraction linearly transmits, and uses hydraulic giant 8 and air gun 7 mixing to be dried,
Easily there are water ripples in the film surface prepared, causes the final battery diaphragm prepared thick
Spend uneven or uneven, and hydraulic giant 8 and air gun 7 inject directly on thin film the most at a certain angle
Surface, impulsive force is big, and the phenomenon such as battery diaphragm outward appearance fold, scollop, scallop is serious,
Affect use and the rolling of battery diaphragm.
According in one embodiment of the present invention, as it is shown in figure 5, described three kinds micro-
Pore structure battery diaphragm includes first outer layer the 9, second outer layer 10 and is clipped in therebetween
Internal layer 11, described first outer layer the 9, second outer layer 10 and internal layer 11 have different micropores
Structure.
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
Compositions for three kinds of microcellular structure battery diaphragms of preparation includes that following weight is joined
The component of ratio:
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 three kinds of microcellular structure battery diaphragms in accordance with the following methods:
Step 1), extrusion: high-molecular polythene and magnesium chloride nano-particle are mixed all
Even, by ultra high molecular polyethylene, 4,4-thiobis (6-tert-butyl-m-cresol), 2,4-
Dihydroxy benaophenonel, octadecyl quaternary ammonium sodium and Tween 80 mix homogeneously, above-mentioned two
Plant mixture and added hot melt by two polyethylene composition charging apertures input extruders respectively
Melt, put into white oil, extrudate flow in extrusion direction by two pore former charging apertures by several times
Prolonging film, extrusion temperature is 210～240 DEG C, and rate of extrusion is 1200g/min；
Step 2), slab: ganoid first slab roller 3 and the second slab roller is set
The temperature of 4 is 20 DEG C, and the casting films of extrusion flows through the first slab roller 3 and the second slab
Space between roller 4, casts the sheet that thickness is 400 μm；
Step 3), longitudinal stretching: the temperature of pre-hot-rolling, draw roll, chill roll is set
It is respectively 80 DEG C, 110 DEG C and 20 DEG C, the most preheated roller of sheet, draw roll and cooling
Roller carries 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 the first cooling zone is respectively 100 DEG C, 115 DEG C and 95 DEG C, and the both sides of thin film are used
Fixture is fixed, and carries out through the first preheating zone, the first drawing zone and the first cooling zone successively
Cross directional stretch, ratio of elongation is 7；
Step 5), extraction: thin film is successively through the first extractant (dichloromethane and phosphoric acid
Trimethyl is by weight the mixture of 22:1 composition) and the second extractant (high purity water)
Soaking 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 the second cooling zone is respectively 115 DEG C, 125 DEG C and 95 DEG C, and the both sides of thin film are used
Fixture is fixed, and carries out through the second preheating zone, the second drawing zone and the second cooling zone successively
Cross directional stretch, obtains three kinds of microcellular structure battery diaphragms, and ratio of elongation is 1.2.
Embodiment 2
Compositions for three kinds of microcellular structure battery diaphragms of preparation includes that following weight is joined
The component of ratio:
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 three kinds of microcellular structure battery diaphragms in accordance with the following methods:
Step 1), extrusion: high-molecular polythene and magnesium chloride nano-particle are mixed all
Even, by ultra high molecular polyethylene, BHT, 4-benzoyl
Epoxide-2,2,6,6-tetramethyl piperidines, octadecyl quaternary ammonium sodium and lauric acid mix homogeneously,
Above two mixture is put in extruder by two polyethylene composition charging apertures respectively
Add heat fusing, put into white oil in extrusion direction by two pore former charging apertures by several times,
Extrusion casting films, extrusion 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 is set
The temperature of 4 is 20 DEG C, and the surface roughness of the first slab roller 3 is 0.1, the second slab
The surface roughness of roller 4 is 0.2, and the casting films of extrusion flows through the first slab roller 3 and second
Space between slab roller 4, casts the sheet that thickness is 400 μm；
Step 3), longitudinal stretching: the temperature of pre-hot-rolling, draw roll, chill roll is set
It is respectively 80 DEG C, 110 DEG C and 20 DEG C, the most preheated roller of sheet, draw roll and cooling
Roller carries 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 the first cooling zone is respectively 100 DEG C, 115 DEG C and 95 DEG C, and the both sides of thin film are used
Fixture is fixed, and carries out through the first preheating zone, the first drawing zone and the first cooling zone successively
Cross directional stretch, ratio of elongation is 7；
Step 5), extraction: thin film is successively through the first extractant (dichloromethane and phosphoric acid
Trimethyl is by weight the mixture of 22:1 composition) and the second extractant (high purity water)
Soaking 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 the second cooling zone is respectively 115 DEG C, 125 DEG C and 95 DEG C, and the both sides of thin film are used
Fixture is fixed, and carries out through the second preheating zone, the second drawing zone and the second cooling zone successively
Cross directional stretch, obtains three kinds of microcellular structure battery diaphragms, and ratio of elongation is 1.2.
Embodiment 3
The present embodiment method therefor is similar to embodiment 2 method therefor, differs only in:
Compositions for three kinds of microcellular structure battery diaphragms of preparation 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
Use the system of battery diaphragm described in embodiment 6 in patent CN201210454073.9
Preparation Method, it may be assumed that the polyethylene that number-average molecular weight is 800,000 g/mol is heated to 180 DEG C
Melted, 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, divides two by mixture
In secondary injection double screw extruder.Temperature within extruder is 200 DEG C, extrusion temperature
Being 190 DEG C, extruded material space extruding between 15 DEG C of chill rolls and adjustable roller is cast
Thickness is the sheet of 1.4mm.Polyethylene is 1:2.4 with the mass ratio of white oil, 2,6-bis-
The quality of tert-butyl-4-methyl-Phenol is the 1.0% of white oil quality.
Sheet obtained above is carried out successively longitudinal stretching and first time cross directional stretch,
The temperature of longitudinal stretching is 100 DEG C, stretching ratio is 5.78, for the first time cross directional stretch
Temperature is 120 DEG C, and stretching ratio is 4.41, after dichloromethane extracts, obtains centre
Barrier film.
Medial septum obtained above carries out second time cross directional stretch, and second time is laterally
The temperature of stretching is 132 DEG C, and stretching ratio is 1.6, and rolling is cut, at 50 DEG C of timeliness
Reason 18h, obtains battery diaphragm.
Experimental example
The battery diaphragm preparing embodiment and comparative example is tested as follows, test knot
Fruit 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 survey
Metering-orifice footpath；
(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 with horizontal
Hot strength；
(6) electronic tensile machine is used to measure the puncture strength of battery diaphragm, longitudinal extension
Rate and horizontal expansion rate；
(7) battery diaphragm percent thermal shrinkage tester is used to measure the longitudinally heat of battery diaphragm
Shrinkage factor and horizontal percent thermal shrinkage；
(8) use battery septum closed pore temperature and broken film temperature tester measure battery every
The closed pore temperature of film 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
Describe in detail.But it is to be understood that, these detailed description of the invention are only to this
Bright illustrative explanations, does not constitute any restriction to protection scope of the present invention.?
In the case of spirit and scope of the present invention, can be in the technology of the present invention
Holding and embodiment carries out various improvement, equivalencing or modification, these each fall within
In protection scope of the present invention.Protection scope of the present invention is as the criterion with claims.
Claims (9)
1. the preparation method of three kinds of microcellular structure battery diaphragms, it is characterised in that the party
Method includes:
Step 1), by melted to polyethylene composition, pore former and optional additive mixed
Close, 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 processes through extractant, is 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 three kinds of microcellular structure electricity
Pond barrier film.
Preparation method the most according to claim 1, it is characterised in that in step 1)
In,
Described polyethylene composition includes 88～92 weight portion high-molecular polythenes and 8～12
Weight portion ultra high molecular polyethylene, and/or
Described pore former includes organic pore former and Inorganic pore forming agents, the most described organic
Pore former is mineral oil, C6-15Alkane, C8-15Aliphatic carboxylic acid, C1-4Alkyl ester, C2-6Halogen
For one or more in alkane, more preferably white oil, the most described Inorganic pore forming agents
For the nano-particle of water-soluble inorganic salt, more preferably magnesium chloride nano-particle,
The addition of the most described organic pore former is polyethylene composition weight
30～60%, the addition of described Inorganic pore forming agents is polyethylene composition weight
1～10%, and/or
The most described pore former is dividedly in some parts, and/or
Described additive includes antioxidant, anti ultraviolet agent, antistatic additive and antifoggant
In one or more, and/or
Described extrusion temperature is 150～250 DEG C, preferably 170～240 DEG C, and/or
Described rate of extrusion is 800～2000g/min, preferably 1000～1500g/min.
Preparation method the most according to claim 1 and 2, it is characterised in that in step
Rapid 2) in,
The temperature of described first slab roller (3) and the second slab roller (4) is 5～40 DEG C,
It is preferably 10～35 DEG C, more preferably 12～33 DEG C, and/or
Optionally by described first slab roller (3) or the surface of the second slab roller (4)
Manage into rough plane, and/or
The thickness of described sheet is 200～600 μm, preferably 250～550 μm, more
It is preferably 300～500 μm.
4. according to the preparation method one of claims 1 to 3 Suo Shu, it is characterised in that
In step 3) in,
The temperature of described pre-hot-rolling is 40～130 DEG C, preferably 50～120 DEG C, more preferably
It is 60～110 DEG C, and/or
The temperature of described draw roll is 70～150 DEG C, preferably 80～140 DEG C, more preferably
It is 90～130 DEG C, and/or
The temperature of described chill roll is 3～50 DEG C, preferably 5～45 DEG C, more preferably
8～40 DEG C, and/or
The ratio of elongation of described longitudinal stretching is 3～10, preferably 3.5～9.5, more preferably
4～9.
5. according to the preparation method one of Claims 1-4 Suo Shu, it is characterised in that
In step 4) in,
The temperature of described first preheating zone is 60～150 DEG C, preferably 70～140 DEG C, more
It is preferably 75～135 DEG C, and/or
The temperature of described first drawing zone is 80～150 DEG C, preferably 85～145 DEG C, more
It is preferably 90～140 DEG C, and/or
The temperature of described first cooling zone is 60～150 DEG C, preferably 70～140 DEG C, more
It is preferably 75～135 DEG C, and/or
The ratio of elongation of described first time cross directional stretch is 3～11, preferably 3.5～10.5,
More preferably 4～10.
6. according to the preparation method one of claim 1 to 5 Suo Shu, it is characterised in that
In step 5) in,
Described extractant includes the first extractant and the second extractant, the most described first
Extractant is the mixture of dichloromethane and phosphate ester composition, and the most described phosphate ester is
One or more in trimethyl phosphate or triethyl phosphate,
The most described dichloromethane is 10:1～40:1 with the weight ratio of phosphate ester, more preferably
For 15:1～30:1, and/or
The most described second extractant is water, and/or
Step 4) thin film that obtains through the first extractant and the second extractant immersion treatment,
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 (6) or parallel with the direction of transfer of thin film.
7. according to the preparation method one of claim 1 to 6 Suo Shu, it is characterised in that
In step 6) in,
The temperature of described second preheating zone is 70～160 DEG C, preferably 80～150 DEG C, more
It is preferably 90～140 DEG C, and/or
The temperature of described second drawing zone is 100～155 DEG C, preferably 105～150 DEG C,
More preferably 110～145 DEG C, and/or
The temperature of described second cooling zone is 60～130 DEG C, preferably 65～135 DEG C, more
It is preferably 70～130 DEG C, and/or
The ratio of elongation of described second time cross directional stretch is 0.5～5, preferably 0.7～4, more
It is preferably 0.8～3.
8. according to the preparation method one of claim 1 to 7 Suo Shu, it is characterised in that
Step 6) battery diaphragm that obtains include the first outer layer (9), the second outer layer (10) and
It is clipped in internal layer (11) therebetween, described first outer layer (9), the second outer layer (10)
With internal layer (11), there is different microcellular structures.
Preparation method the most according to claim 8, it is characterised in that described
The average pore size of one outer layer (9) is 20～100nm, the second outer layer (10) average
Aperture is 30～140nm, and the aperture of internal layer (11) is 50～180nm.
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| 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 |
| CN110828751A (en) * | 2019-11-06 | 2020-02-21 | 江苏厚生新能源科技有限公司 | Preparation method of polyethylene diaphragm with multilayer microporous structure |
| CN113471626A (en) * | 2018-07-18 | 2021-10-01 | 河南义腾新能源科技有限公司 | Polyethylene diaphragm and preparation method thereof |
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