CN106328860B - A kind of lithium ion battery separator and used pore former combination object of resistance to thermal contraction - Google Patents
A kind of lithium ion battery separator and used pore former combination object of resistance to thermal contraction Download PDFInfo
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- CN106328860B CN106328860B CN201510348902.9A CN201510348902A CN106328860B CN 106328860 B CN106328860 B CN 106328860B CN 201510348902 A CN201510348902 A CN 201510348902A CN 106328860 B CN106328860 B CN 106328860B
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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
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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
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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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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- 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 the lithium ion battery separator of resistance to thermal contraction and used pore former combination objects, the pore former combination object includes organic pore former and Inorganic pore forming agents, wherein, it is preferred that organic pore former is higher boiling small organic molecule, it is preferred that Inorganic pore forming agents are water-soluble inorganic nano particle, the pore former and optional additive are added in film forming matter jointly, tool is formed after slab is processed, and there are three types of the lithium ion battery separators of microcellular structure, and there is good lower closed pore temperature simultaneously, thermal shrinkage, tensile strength, puncture strength and higher broken film temperature, to ensure that the safety when making and using lithium ion battery.
Description
Technical field
The present invention relates to the preparation processes of battery diaphragm, and in particular to a kind of lithium ion battery separator of resistance to thermal contraction and
Pore former combination object used in its preparation process.
Background technique
Lithium ion battery is widely used in the fields such as telecommunications, energy storage and electrical source of power, mainly by anode, cathode, electricity
Matter and battery diaphragm is solved to constitute, wherein battery diaphragm be it is nonconducting, be located between anode and cathode, both prevent because of contact
And it is short-circuit, while electrolyte ion being allowed to pass through, to generate electric current, current battery diaphragm is mostly to have gathering for microcellular structure
Alkene film, performance determine the interfacial structure of battery, internal resistance etc., directly affect capacity, circulation and the security performance of battery
Etc. characteristics, the battery diaphragm haveing excellent performance to improve battery comprehensive performance play a significant role.
The performance of battery diaphragm is mainly characterized with following index: partition property requires battery diaphragm to have partition property and electronics
Insulating properties guarantees effective mechanical isolation of positive and negative electrode；Porosity requires diaphragm to have certain aperture and porosity, guarantees low
Resistance and high ionic mobility, have good permeability to lithium ion；Chemical stability and electrical stability require diaphragm tool
Standby moisture-proof and electrolyte resistance corrosivity；Wellability requires diaphragm good to the wellability of electrolyte, and there is preferable imbibition to protect
Wet ability and ion permeability；Mechanical strength require diaphragm to guarantee while thickness is as small as possible enough mechanical properties and
Shock resistance, including puncture strength and tensile strength；Security requirement diaphragm will have thermal stability and automatically shut down protective value,
Including closed pore temperature and broken film temperature.To be mutually related between the multinomial performance index of battery diaphragm, it is desirable to take into account multinomial performance,
Obtain the preferable battery diaphragm of indices still has larger difficulty at present.
Existing polyolefin battery separation film preparation method is broadly divided into wet process and dry method, wherein the preparation process packet of wet process
It includes: being added in polyolefin using higher boiling small molecule as pore former, heating melting is at homogeneous system, and then phase point occurs for cooling
From extracting small molecule with organic solvent after biaxial tension, the micro-pore septum being mutually communicated can be prepared.
There are some defects for traditional battery diaphragm wet method preparation process, comprising: one is generallyd use during slab
Slab roller with refrigerating function carries out single side cooling, and pore former closing not exclusively, easily flows out, micropore is caused to be unevenly distributed；
Extrusion equipment in different production steps is different, causes product quality pattern different, is difficult to control consistency；It usually squeezes and sets
It is standby, stretcher roller surface is smooth, the membrane surface produced is smooth, poor with the adhesive force of other materials, is unfavorable for researching and developing
Novel battery diaphragm；Drying equipment generallys use hydraulic giant and air gun two ways while carrying out after extraction, causes the surface of diaphragm
Usually there is water wave, and flatness is not good enough.
Above-mentioned condition based on the prior art, the present inventor study the preparation process of battery diaphragm, it is therefore an objective to mention
For the resistance to preparation method for being heat-shrinked battery diaphragm and using the battery diaphragm made from this method with resistance to thermal contraction.
Summary of the invention
In order to overcome the above problem, the present inventor has carried out sharp study to the preparation method of battery diaphragm, as a result, it has been found that:
By using the pore former combination object that the organic pore former and Inorganic pore forming agents of specific proportion are composed, it is added with polyphosphazene polymer
Ethylene and ultra high molecular polyethylene are in the mixture of film-forming components, and optionally add other additives, by specific device
After technique processing, can be had lower closed pore temperature, higher broken film temperature and good mechanical strength and good resistance to simultaneously
The lithium ion battery separator of heat-shrinkable, thereby completing the present invention.
The purpose of the present invention is to provide following aspect:
In a first aspect, the present invention provides a kind of pore former combination of lithium ion battery separator for being used to prepare resistance to thermal contraction
Object, which is characterized in that the composition includes organic pore former and Inorganic pore forming agents,
Preferably,
The organic pore former is selected from higher boiling small organic molecule；
The Inorganic pore forming agents are selected from water-soluble inorganic nano particle.
Second aspect, the present invention also provides above-mentioned pore former combination objects, which is characterized in that
The higher boiling small organic molecule is that boiling point is higher than 200 DEG C, and number-average molecular weight is organic less than 500 liquid
Object；
The water-soluble inorganic nano particle is the particles of inorganic material that partial size is 1~200nm.
The third aspect, the present invention also provides above-mentioned pore former combination objects, which is characterized in that the higher boiling small molecule is organic
Object is preferably selected from mineral oil, C6-15Alkane, C8-15Aliphatic carboxylic acid, C1-4Alkyl ester, C2-6One of halogenated alkane is a variety of, more excellent
Selection of land,
The mineral oil is white oil；The C6-15Alkane is selected from heptane, naphthalane, decane, hendecane and dodecane；It is described
C8-15Aliphatic carboxylic acid is selected from capric acid, hendecoic acid and lauric acid；The C1-4Alkyl ester is selected from methyl caprate, ethyl caprate, capric acid
Propyl ester, capric acid N-butyl, hendecoic acid methyl esters, hendecoic acid ethyl ester, hendecoic acid propyl ester, hendecoic acid N-butyl, 12 carbon
Sour methyl esters, dodecanoate, lauric acid propyl ester, lauric acid N-butyl；The C2-6Halogenated alkane be selected from dichloroethanes,
Dichloropropane, chlorofluoroethane and fluorine chloropropane；And/or
The water-soluble inorganic nano particle is selected from water-soluble nano sulfate, water-soluble nano nitrate, water solubility and receives
One of m+ hydrochloric acid salt is a variety of, it is highly preferred that
The water-soluble nano sulfate is selected from nanometer sodium sulphate, nanometer potassium sulfate and nanometer ammonium sulfate etc.；It is described water-soluble
Property nanometer nitrate be selected from nanometer sodium nitrate, nanometer potassium nitrate, nanometer ammonium nitrate, nanometer magnesium nitrate and nanometer copper nitrate etc.；Institute
It states water-soluble nano hydrochloride and is selected from nanometer sodium chloride, nanometer potassium chloride, nanometer ammonium chloride, nanometer magnesium chloride, nanometer calcium chloride
With nanometer copper chloride etc..
Fourth aspect, the present invention also provides above-mentioned pore former combination objects, which is characterized in that the organic pore former with it is described
The weight ratio of Inorganic pore forming agents is (30~60): (1~10), preferably (35~55): (2~8), more preferably (40~50):
(4~6).
5th aspect, the present invention also provides above-mentioned pore former combination objects, which is characterized in that the organic pore former is preferably
White oil, the Inorganic pore forming agents are preferably nanometer magnesium chloride, and the preferably described pore former is the composition of white oil and nanometer magnesium chloride.
6th aspect, the present invention also provides above-mentioned pore former combination objects, which is characterized in that the pore former is added to polyene
In hydrocarbon, it is preferable that in terms of being 100 parts by weight by the weight of polyolefin, the additional amount of pore former is 20~70 parts by weight, preferably 30
~60 parts by weight, more preferably 50 parts by weight.
7th aspect, the present invention also provides above-mentioned pore former combination objects, which is characterized in that the pore former preferably adds in batches
Enter in polyolefin.
Eighth aspect, the present invention provide a kind of preparation method of the lithium ion battery separator of resistance to thermal contraction, which is characterized in that
This method comprises:
Step 1), by polyethylene or combinations thereof object, above-mentioned pore former combination object and optional other additive melting mixings,
Squeeze out casting films；
Step 2), the casting films that step 1) squeezes out flow through the gap between the first slab roller and the second slab roller, cast thickness
Piece；
Step 3), successively preheated roller, draw roll and chill roll carry out longitudinal stretching to the sheet that step 2) obtains；
Step 4), the film two sides that step 3) obtains are fixed, successively cooling through the first preheating zone, the first drawing zone and first
Area carries out cross directional stretch；
Step 5), the film that step 4) obtains are handled through extractant, are then dried；Preferably, the drying is filled dry
Middle progress is set, the drying device includes multiple transfer rollers arranged at broken line, is set in the position that film is in contact with transfer roller
Be equipped with for dry air gun, the jet direction of the preferably described air gun preferably with the plane tangent of the transfer roller or with film
Direction of transfer is parallel；
Step 6), the film two sides that step 5) obtains are fixed, successively cooling through the second preheating zone, the second drawing zone and second
Area carries out second of cross directional stretch, obtains the battery diaphragm of resistance to thermal contraction.
9th aspect, it is special the present invention also provides the lithium ion battery separator of the resistance to thermal contraction using above method preparation
Sign is, which includes the first outer layer, the second outer layer and be clipped in internal layer between the two, first outer layer, second
Outer layer and internal layer have different microcellular structures,
It is preferred that the average pore size of first outer layer is 20~100nm, the average pore size of the second outer layer is 30~140nm,
The aperture of internal layer is 50~180nm.
Another object of the present invention, which also resides in provide, a kind of implements device used in above-mentioned preparation method comprising squeezes out dress
It sets, cooling roller device and drying device, wherein
The extrusion device include machine barrel, two polyethylene composition feed inlets for being disposed in parallel in described machine barrel one end and
It is respectively arranged on the machine barrel away from two pore formers that the polyethylene composition feed inlet is at 1/3 and 2/3 barrel length
Feed inlet, and/or
The cooling roller device includes the first slab roller and the second slab roller that spacing is 180~580 μm, first casting
The diameter of piece roller and the second slab roller ratio is 1:(1~6), first slab roller and the second slab roller rotate towards each other, it is preferable that
The roller linear velocity numerical value of the roller linear velocity of first slab roller and second slab roller is equal, and/or
The drying device includes multiple transfer rollers arranged at broken line, is arranged in the position that film is in contact with transfer roller
Have for dry air gun, the jet direction of the preferably described air gun and the plane tangent of the transfer roller.
The present invention described below.
According to the present invention first to the 7th aspect, provides a kind of pore former of battery diaphragm for being used to prepare resistance to thermal contraction
Composition, which is characterized in that the composition includes organic pore former and Inorganic pore forming agents, it is preferable that
The organic pore former is higher boiling small organic molecule, it is preferable that higher boiling small organic molecule is that boiling point is high
In 200 DEG C, and liquid state organics of the number-average molecular weight less than 500, preferably mineral oil, C6-15Alkane, C8-15Aliphatic carboxylic acid, C1-4
Alkyl ester, C2-6One of halogenated alkane is a variety of, wherein
The C6-15Alkane is selected from heptane, naphthalane, decane, hendecane and dodecane, the C8-15Aliphatic carboxylic acid is selected from the last of the ten Heavenly stems
Acid, hendecoic acid and lauric acid, the C1-4Alkyl ester is selected from methyl caprate, ethyl caprate, capric acid propyl ester, capric acid N-butyl, ten
One methyl carbonate, hendecoic acid ethyl ester, hendecoic acid propyl ester, hendecoic acid N-butyl, lauric acid methyl esters, lauric acid second
Ester, lauric acid propyl ester, lauric acid N-butyl, the C2-6Halogenated alkane is selected from dichloroethanes, dichloropropane, chlorofluoroethane
With fluorine chloropropane.
The organic pore former is more preferably white oil.
The Inorganic pore forming agents are selected from water-soluble inorganic nano particle, it is preferable that water-soluble inorganic nano particle is selected from grain
Diameter is 1~200nm, water-soluble nano sulfate, the water-soluble nano nitric acid of preferably 3~100nm, more preferably 5~20nm
One of salt, water-soluble nano hydrochloride etc. are a variety of, wherein
The water-soluble nano sulfate is selected from nanometer sodium sulphate, nanometer potassium sulfate and nanometer ammonium sulfate etc., described water-soluble
Property nanometer nitrate be selected from nanometer sodium nitrate, nanometer potassium nitrate, nanometer ammonium nitrate, nanometer magnesium nitrate and nanometer copper nitrate etc., institute
It states water-soluble nano hydrochloride and is selected from nanometer sodium chloride, nanometer potassium chloride, nanometer ammonium chloride, nanometer magnesium chloride, nanometer calcium chloride
With nanometer copper chloride etc..
The Inorganic pore forming agents are more preferably nanometer magnesium chloride.
It is highly preferred that the pore former is the composition of white oil and nanometer magnesium chloride.
In pore former, the weight ratio of the organic pore former and the Inorganic pore forming agents is (30~60): (1~10),
Preferably (35~55): (2~8), more preferably (40~50): (4~6).
It is highly preferred that the pore former is the composition of white oil and nanometer magnesium chloride, wherein white oil and nanometer magnesium chloride
Weight ratio is (30~60): (1~10), preferably (35~55): (2~8), more preferably (40~50): (4~6), such as 45:
5。
In the present invention, the pore former is added into polyolefin, it is preferable that with the weight of polyolefin for 100 parts by weight
Meter, the additional amount of pore former are 20~70 parts by weight, preferably 30~60 parts by weight, more preferably 50 parts by weight.
The inventors discovered that when preparing lithium ion battery separator, be added the pore former into preparation system, it is described at
Hole agent can be dispersed in film forming matter, especially polyolefin in the form of fine droplet and solid granule, especially poly-
In the molten state composition that ethylene is formed, after its cooling film forming, pore former still is able in film with fine droplet and solid
Short grained form is present in the slab of film, forms " occupy-place " effect, after the slab of film is stretched, pore former is extracted out
Film, then it can leave correspondingly micropore on film, and lithium ion battery separator obtained is made to have microcellular structure, thus lithium from
When sub- battery works, the lithium ion for deviating from positive electrode can pass through battery diaphragm.
The present inventors have additionally discovered that film forming matter molten state is added portionwise from different pore former feed openings in the pore former
In composition, pore former degree of scatter in preparation system is higher, and microwave drop and solid granule are more uniformly spread, from
And keep the aperture of every layer of microporous layers of lithium ion battery separator obtained all relatively uniform.
In addition, the present inventor also has surprisingly found that, Inorganic pore forming agents are in the mixing process for preparing lithium ion battery separator
With stronger plasticising thickening power, the partial size of aggregated particle is made to become smaller, the big aggregation of generation is able to suppress, thus made from improving
The puncture strength of lithium ion battery separator.
In the present invention, it is preferred to which it includes the polyethylene of following weight proportion or combinations thereof object that the pore former, which is added,
In,
93~98 parts by weight of high molecular polythene,
2~7 parts by weight of ultra high molecular polyethylene,
Preferably,
94~96 parts by weight of high molecular polythene
4~6 parts by weight of ultra high molecular polyethylene,
More preferably,
95 parts by weight of high molecular polythene
5 parts by weight of ultra high molecular polyethylene.
In a preferred embodiment of the present invention, the pore former can also be with the addition including following weight proportion
It is used cooperatively,
Preferably,
More preferably,
Wherein,
The antioxidant is selected from 4,4- thiobis (6- tert-butyl-m-cresol), dibutyl hydroxy toluene, phosphite ester, spy
Butylhydroquinone, preferably 4,4- thiobis (6- tert-butyl-m-cresol), tert-butylhydroquinone, wherein the dibutyl
Hydroxy-methylbenzene is 3,5-di-tert-butyl-4-hydroxytoluene, and the antioxidant is more preferably 4,4- thiobis (first between 6- tert-butyl
Phenol).
The inventors discovered that antioxidant is able to suppress the oxidative degradation of high molecular polythene and ultra high molecular polyethylene,
It is set to maintain higher number-average molecular weight, to ensure that the function admirable of lithium ion battery separator obtained.
The anti ultraviolet agent be selected from salicylic acid esters, benzophenone class, benzotriazole, group-substituted acrylonitrile, triazines and by
Hindered amine, such as septichen phenyl ester, 2- (- 5 ˊ of 2 ˊ-hydroxyl-aminomethyl phenyl) benzotriazole, 2,4- dihydroxy hexichol first
Ketone, ESCALOL 567,2-hydroxy-4-n-octoxybenzophenone, 2- (the tertiary benzene of 2'- hydroxyl -3', 5'- bis-
Base) -5- chlorination benzotriazole, single benzoic acid resorcinol, three (1,2,2,6,6- pempidine base) phosphite esters, 4- benzene first
Acyloxy -2,2,6,6- tetramethyl piperidines, 2,4,6- tri- (2' n-butoxyphenyl) -1,3,5-triazines and hexamethylphosphoramide
Deng.
The inventors discovered that anti ultraviolet agent can absorb ultraviolet light, ultraviolet light is reduced to obtained lithium ion battery separator
Radiolysis enhances its anti-aging property, extends the service life of lithium ion battery separator.
The antistatic agent is selected from cationic antistatic agent, anionic antistatic agents and non-ionic antistatic agent, preferably
Quaternary ammonium salt, ethoxy are alkylated aliphatic alkyl amine, such as octadecyl quaternary ammonium sodium.
The antifoggant is selected from the ester of xylitol, sorbierite monopalmitate, lauric acid, span series, spits
Warm series of surfactants or animi resin monoglyceride, preferably span series and TWEEN Series surface-active
Agent.
According to another aspect of the present invention, the pore former is applied to a kind of lithium ion battery prepared with resistance to thermal contraction
In the preparation method of diaphragm, method includes the following steps:
Step 1) squeezes out: above-mentioned polyethylene or combinations thereof object, pore former and optional additive melting mixing squeeze out
Casting films.
In a preferred embodiment in accordance with the present invention, described polyethylene or combinations thereof object preferably be selected from high molecular polythene and
Ultra high molecular polyethylene, more preferably high molecular polythene and ultra high molecular polyethylene are by weight (93~98): (2~7), into
One step is preferably (94~96): the composition of (4~6), more preferably 95:5 composition, the equal molecule of the number of the high molecular polythene
Amount is 100,000~600,000, preferably 200,000~500,000, more preferably 300,000~400,000, and the number of the ultra high molecular polyethylene is divided equally
Son amount is 1,200,000~1,500,000, preferably 1,300,000~1,400,000.
In a preferred embodiment in accordance with the present invention, the pore former includes organic pore former and Inorganic pore forming agents,
In, the organic pore former is higher boiling small organic molecule, it is preferable that the higher boiling small organic molecule is higher than for boiling point
200 DEG C, and liquid state organics of the number-average molecular weight less than 500, preferably mineral oil, C6-15Alkane, C8-15Aliphatic carboxylic acid, C1-4Alkane
Ester, C2-6One of halogenated alkane is a variety of, wherein
The mineral oil is preferably white oil, the C6-15Alkane is selected from heptane, naphthalane, decane, hendecane and dodecane, institute
State C8-15Aliphatic carboxylic acid is selected from capric acid, hendecoic acid and lauric acid, the C1-4Alkyl ester is selected from methyl caprate, ethyl caprate, the last of the ten Heavenly stems
Propyl propionate, capric acid N-butyl, hendecoic acid methyl esters, hendecoic acid ethyl ester, hendecoic acid propyl ester, hendecoic acid N-butyl, 12
Methyl carbonate, dodecanoate, lauric acid propyl ester, lauric acid N-butyl, the C2-6Halogenated alkane is selected from two chloroethenes
Alkane, dichloropropane, chlorofluoroethane and fluorine chloropropane,
The organic pore former is more preferably mineral oil, more preferably white oil.
The Inorganic pore forming agents are water-soluble inorganic nano particle, it is preferable that the water-soluble inorganic nano particle is grain
Diameter is 1~200nm, water-soluble nano sulfate, the water-soluble nano nitric acid of preferably 3~100nm, more preferably 5~20nm
One of salt, water-soluble nano hydrochloride are a variety of, wherein
The water-soluble nano sulfate is selected from nanometer sodium sulphate, nanometer potassium sulfate and nanometer ammonium sulfate etc., described water-soluble
Property nanometer nitrate be selected from nanometer sodium nitrate, nanometer potassium nitrate, nanometer ammonium nitrate, nanometer magnesium nitrate and nanometer copper nitrate etc., institute
It states water-soluble nano hydrochloride and is selected from nanometer sodium chloride, nanometer potassium chloride, nanometer ammonium chloride, nanometer magnesium chloride, nanometer calcium chloride
With nanometer copper chloride etc..
Compared to organic pore former, the Inorganic pore forming agents of the solid granular have bigger partial size and fixed shape
State, thus there is stronger occupy-place effect, the bigger microcellular structure in aperture can be formed in battery diaphragm, can preferably control shape
At the size, shape and distribution of micropore, and be conducive to improve the porosity and air permeability of battery diaphragm, such as: can be by selecting not
The different battery diaphragm of micropore size is made with the Inorganic pore forming agents of partial size.
By the sum of the weight of polyethylene or combinations thereof weight of object be 100 parts by weight in terms of, the additional amount of the pore former is
20~70 parts by weight, preferably 30~60 parts by weight, more preferably 50 parts by weight, wherein the organic pore former and the nothing
The weight ratio of machine pore former is (30~60): (1~10), preferably (35~55): (2~8), more preferably (40~50): (4
~6).
In a preferred embodiment in accordance with the present invention, the process of the melting mixing and extrusion in extruder or squeezes out dress
Middle progress is set, the extruder or extrusion device include machine barrel, two polyethylene compositions for being disposed in parallel in described machine barrel one end
Object feed inlet and be respectively arranged on the machine barrel away from the polyethylene composition feed inlet be 1/3 and 2/3 barrel length at
Two pore former feed inlets.
By polyethylene composition, Inorganic pore forming agents and optional additive be pre-mixed uniformly after through polyethylene composition into
Material mouth puts into extruder, is preferably pre-mixed uniformly Inorganic pore forming agents and high molecular polythene, by optional additive and surpasses
High molecular polythene is pre-mixed uniformly, puts into extruder through two different polyethylene composition feed inlets, then heating is molten
Melt, organic pore former is added on the extrusion direction of the polyethylene composition of extruder inner molten, the organic pore former is excellent
Choosing is separately added into extruder from two different pore former feed inlets in batches, melts and squeezes out casting films after mixing, uses
The Inorganic pore forming agents and organic pore former is added in above-mentioned preferred mode, can avoid polyethylene composition and phase occurs in pore former
It separates and causes mixing uneven and with pressure oscillation in extruder, so that polyethylene composition and pore former are sufficiently mixed
Even, pore former is uniformly distributed in polyethylene composition, is conducive to the aperture that micropore is prepared in subsequent step and distribution more
Uniform battery diaphragm.
In a preferred embodiment in accordance with the present invention, it is optionally added into the additive of following weight proportion,
In a preferred embodiment in accordance with the present invention, described polyethylene or combinations thereof object, pore former and optional addition
Agent can be mixed first, be again heated to molten condition, can also first distinguish heating melting, then the above-mentioned substance of melting is blended in one
It rises, the polyethylene or combinations thereof object, pore former and optional additive are preferably first uniformly mixed by the present invention respectively, are added
It is heated to molten condition in extruder and is stirred, is uniformly mixed, and easy to operate, low energy consumption.
In a preferred embodiment in accordance with the present invention, extrusion temperature and rate of extrusion, which directly affect, is made thickness in step 2)
The character and thickness of piece, and determine the every physicochemical property for finally preparing diaphragm.Extrusion temperature is higher, the mobility of casting films
Better, molecule confusion degree is higher, and the crystallinity that diaphragm is made is poorer；Extrusion temperature is lower, and the mobility of casting films is poorer, point
Sub- confusion degree is lower, and degree of molecular orientation is higher, and the crystallinity that diaphragm is made is better, and extrusion temperature is 150~250 in the present invention
DEG C, preferably 170~240 DEG C.Rate of extrusion is too fast, and casting films were accumulated between the first slab roller 3 and the second slab roller 4
It is more, it may cause Local cooling and be hardened and influence slab progress；Rate of extrusion is excessively slow, and it is uneven to may cause slab thicknesses obtained
Or it is excessively thin, rate of extrusion is 800~2000g/min, preferably 1000~1500g/min in the present invention.
Step 2), slab: the casting films that step 1) squeezes out flow through the gap between the first slab roller and the second slab roller, cast
At sheet.
The cooling roller device includes the first slab roller and the second slab roller that spacing is 180~580 μm, first casting
The diameter of piece roller and the second slab roller ratio is 1:(1~6), first slab roller and the second slab roller rotate towards each other, it is preferable that
The roller linear velocity numerical value of the roller linear velocity of first slab roller and second slab roller is equal.
In a preferred embodiment in accordance with the present invention, as shown in Fig. 2, first slab roller and the second slab roller are opposite
Rotation, the casting films squeezed out from extruder die head form accumulation between the first slab roller and the second slab roller, then pass through two
Gap between person squeezes, cools down, and casts sheet, reduces the factors pair such as rate of extrusion is uneven and extruder machinery shakes
The influence of sheet character, to prepare the sheet that thickness is uniform, character is stable.
In a preferred embodiment in accordance with the present invention, the surface temperature of 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 flow through the first slab roller and the second slab
Two-sided cooling and shaping, cast sheet when gap between roller, meanwhile, it is uniformly distributed pore former and polyethylene composition inside it
Thermotropic phase separation occurs for object, and the sheet of two-sided cooling closes pore former inside it, with single side cooling in traditional handicraft
Sheet is compared, and pore former is less susceptible to ooze out, and is conducive to that the aperture of micropore is made, is distributed more uniform battery diaphragm.
It in a preferred embodiment in accordance with the present invention, optionally will be at the surface of first slab roller or the second slab roller
Manage into rough plane, the coarse battery diaphragm of single or double can be prepared, improve membrane surface to other materials (such as:
Coating, film etc.) adhesive force, for research and development novel battery diaphragm lay a good foundation.
In a preferred embodiment in accordance with the present invention, the thickness of the sheet directly affects the thickness of final obtained diaphragm
Degree, in general, sheet is thicker, and diaphragm obtained is thicker, can be by adjusting the sky between the first slab roller and the second slab roller
Gap width adjusts the thickness of sheet, heretofore described sheet with a thickness of 200~600 μm, preferably 250~550 μm, more
Preferably 300~500 μm.
Step 3), longitudinal stretching: successively preheated roller, draw roll and chill roll carry out longitudinal drawing to the sheet that step 2) obtains
It stretches.
In a preferred embodiment in accordance with the present invention, sheet roller preheated first is preheated with lower temperature, softening
Sheet prepares to stretch, prevents sheet from leading to character cataclysm because being heated at high temperature suddenly；Then, the sheet is through multiple turns
The draw roll that speed gradually rises carries out longitudinal stretching at high temperature；Finally, being formed through chill roll sub-cooled, obtains character and fix
Film.After longitudinal stretching, film elongates in the longitudinal direction compared with sheet, and thickness is thinning, and longitudinal mechanical strength is mentioned
Height, meanwhile, the micropore of internal pore former occupy-place is longitudinally elongated at elongate.
In a preferred embodiment in accordance with the present invention, the temperature of the pre- hot-rolling be 40~130 DEG C, preferably 50~
120 DEG C, more preferably 60~110 DEG C preheat sheet, prepare to stretch；
The temperature of the draw roll is 70~150 DEG C, and preferably 80~140 DEG C, more preferably 90~130 DEG C are guaranteeing
The micropore of pore former occupy-place is made to reach suitable aperture while sheet good tensile property；
The temperature of the chill roll is 3~50 DEG C, preferably 5~45 DEG C, more preferably 8~40 DEG C, so that drawing by high temperature
The rapid cooling and shaping of film afterwards, length, thickness and aperture after keeping longitudinal stretching.
In a preferred embodiment in accordance with the present invention, the revolving speed of the multiple draw roll is in 2~40m/min range manhole ladder
Degree increases, so that stretching uniformly, adjusts the longitudinal stretching degree of film by adjusting the revolving speed of draw roll, obtains different prolong
Stretch ratio.
The ratio of elongation of the longitudinal stretching is 3~10, preferably 3.5~9.5, more preferably 4~9, and it is suitable to obtain having
Thickness, aperture and longitudinal mechanical strength film.
Step 4), first time cross directional stretch: the film two sides that step 3) obtains are fixed, successively through the first preheating zone, first
Drawing zone and the first cooling zone carry out cross directional stretch.
In a preferred embodiment in accordance with the present invention, the film two sides are fixed with fixture respectively, first passes around
One preheating zone is preheated, and film is softened, and is prepared to stretch；Then, cross directional stretch is carried out at high temperature through the first drawing zone,
Distance is gradually increased between symmetrical fixture；Finally, being formed through the first cooling zone sub-cooled, the fixed film of character is obtained.Through
For the first time after stretching horizontally, film horizontally elongates, and thickness is thinning, and lateral mechanical strength is improved, meanwhile, inside
The micropore horizontal elongation of pore former occupy-place is at similar round.
In a preferred embodiment in accordance with the present invention, the temperature of first preheating zone be 60~150 DEG C, preferably 70
~140 DEG C, more preferably 75~135 DEG C, preheated film are prepared to stretch；
The temperature of first drawing zone is 80~150 DEG C, preferably 85~145 DEG C, more preferably 90~140 DEG C,
Guarantee to make the micropore of pore former occupy-place reach suitable aperture while film good tensile property；
The temperature of first cooling zone is 60~150 DEG C, and preferably 70~140 DEG C, more preferably 75~135 DEG C make
The rapid cooling and shaping of film after obtaining drawing by high temperature keeps length, thickness and aperture for the first time after stretching horizontally.
In a preferred embodiment in accordance with the present invention, the film at the uniform velocity moves in the longitudinal direction, by adjusting laterally folder
Distance between tool adjusts the cross directional stretch degree of film, obtains different ratios of elongation.
The first time ratio of elongation stretching in the transverse direction is 3~11, preferably 3.5~10.5, more preferably 4~10, is obtained
Film with suitable thickness, aperture and lateral mechanical strength.
Step 5), extraction: the film that step 4) obtains successively is handled through extractant, is then dried.
In a preferred embodiment in accordance with the present invention, the extractant preferably includes the first extractant and the second extraction
Agent, the film that step 4) obtains is successively through the first extractant and the second extractant immersion treatment.
In a preferred embodiment in accordance with the present invention, preferably pore former is extracted in two times, first with the first extraction
Agent extracts the organic pore former component in pore former, then the Inorganic pore forming agents component in pore former is extracted with water.With first
When extractant and the second extractant impregnate film, be evenly distributed on the pore former inside film be dissolved extract out, originally by
The position that hole agent occupies forms microcellular structure, and whether the distribution of micropore and aperture are uniformly distributed with pore creating material in film
Even dispersion is directly related；First extractant is good to the organic pore former component dissolubility in pore former, and is not dissolved thin
The reagent of polyethylene composition and additive in film, the mixing that the present invention preferably selects methylene chloride and phosphate to form
Object, the phosphate are preferably one or more of trimethyl phosphate and triethyl phosphate, wherein methylene chloride and phosphate
Weight ratio be 10:1~40:1, preferably 15:1~30:1, the organic extractant is better than organic pore former effect of extracting
Simple methylene chloride, extraction is more complete, and pore former residual is few；Second extractant is to the Inorganic pore forming agents in pore former
Component dissolubility is good, and without the reagent of polyethylene composition and additive in dissolving films, the present invention preferably selects water, more
Preferably high purity water.
It is dried in drying device.The drying device includes multiple transfer rollers arranged at broken line.According to this
In the preferred embodiment of invention, it is provided in the position that film is in contact with transfer roller for dry air gun, it is preferably described
The plane tangent of the jet direction of air gun and the transfer roller.
Film extracted is dried using air gun, to remove the remaining extractant of film surface, prevents stain
Mark, the air gun drying effect is good, and effectively prevents the generation of film surface water ripples, meanwhile, by reasonably adjusting gas
The position of rifle and film significantly improves finally obtained battery diaphragm so that the vertical impact forces of film are obviously reduced in air gun
The bad phenomenons such as appearance fold, scollop, scallop.
Step 6), second of cross directional stretch: the film two sides that step 5) obtains are fixed, successively through the second preheating zone, second
Drawing zone and the second cooling zone carry out second of cross directional stretch, obtain the battery diaphragm of resistance to thermal contraction.
In a preferred embodiment in accordance with the present invention, the two sides of the film are fixed with fixture, first passes around second
Preheating zone is preheated, and film is softened, and is prepared to stretch；Then, it carries out slightly laterally drawing at high temperature through the second drawing zone
It stretches, distance is gradually increased between symmetrical fixture；Finally, being formed through the second cooling zone sub-cooled, the heat-resisting of character fixation is obtained
The battery diaphragm of contraction.Compared with first time cross directional stretch, level of stretch is substantially reduced second of cross directional stretch, horizontal through second
To after stretching, the film with microcellular structure is horizontally slightly elongated or is remained unchanged, and makes its machine by heating-cooling process
Tool intensity, air permeability, heat-shrinkable can be further improved, meanwhile, internal micropore horizontal elongation, aperture increases are had
There is the battery diaphragm of the resistance to thermal contraction of good character.
In a preferred embodiment in accordance with the present invention, the temperature of second preheating zone be 70~160 DEG C, preferably 80
~150 DEG C, more preferably 90~140 DEG C, preheated film are prepared to stretch；
The temperature of second drawing zone is 100~155 DEG C, preferably 105~150 DEG C, more preferably 110~145 DEG C,
Micropore is made to reach suitable aperture while guarantee film good tensile property；
The temperature of second cooling zone is 60~130 DEG C, and preferably 65~135 DEG C, more preferably 70~130 DEG C make
The rapid cooling and shaping of film after obtaining drawing by high temperature keeps length, thickness and aperture for the second time after stretching horizontally.
In a preferred embodiment in accordance with the present invention, the film at the uniform velocity moves in the longitudinal direction, by adjusting laterally folder
Distance between tool adjusts the cross directional stretch degree of film, obtains different ratios of elongation.
Second of ratio of elongation stretching in the transverse direction is 0.5~5, preferably 0.7~4, more preferably 0.8~3, is had
There is the battery diaphragm of the resistance to thermal contraction of suitable thickness, aperture, mechanical strength and thermal contraction performance.
According to the present invention, the battery diaphragm using the resistance to thermal contraction such as above method preparation is provided, which is characterized in that as schemed
Shown in 5, which includes the first outer layer, the second outer layer and is clipped in internal layer between the two, first outer layer, the second outer layer and
Internal layer has different microcellular structures.
In a preferred embodiment in accordance with the present invention, the aperture of first outer layer is 20~100nm, the second outer layer
Aperture is 30~140nm, and the aperture of internal layer is 50~180nm.
In a preferred embodiment in accordance with the present invention, the performance of the diaphragm is as follows:
With a thickness of 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, preferably 220~380sec, more preferably 250~350sec；
Longitudinal tensile strength is 1800~2200kgf/cm2, preferably 1850~2150kgf/cm2, more preferably 1900~
2100kgf/cm2；
Transverse tensile strength is 1800~2500kgf/cm2, preferably 1900~2450kgf/cm2, more preferably 2000~
2400kgf/cm2；
Puncture strength is 600~1000gf, preferably 640~950gf, more preferably 660~900gf；
Longitudinal elongation percentage is 160~220%, preferably 170~210%, more preferably 180~200%；
Being laterally extended rate is 150~210%, preferably 160~200%, more preferably 170~195%；
Longitudinal percent thermal shrinkage is not more than 3%, preferably no greater than 2.8%, more preferably no more than 2.5%；
Lateral percent thermal shrinkage is not more than 1%, 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.
It is stretched by force using battery diaphragm made from pore former provided by the invention is with higher while thickness is lower
Degree and puncture strength, can be used for preparing the smaller battery of volume, and stronger mechanical force can be born in battery assembling process, no
Cracky；In addition, porosity and venting quality are high, internal resistance of cell made from it is low, and capacitance is opposite to be improved；And percent thermal shrinkage
It is low, reduce the problems such as causing battery breaking because of diaphragm heat shrinkable in the use process of battery；Meanwhile having lower
Closed pore temperature and higher broken film temperature, it is highly-safe.
According to the present invention, device used in the preparation method of three kinds of microcellular structure battery diaphragms as described above includes squeezing out
Device, cooling roller device and drying device.
The extrusion device include machine barrel, two polyethylene composition feed inlets for being disposed in parallel in described machine barrel one end and
It is respectively arranged on the machine barrel away from two pore formers that the polyethylene composition feed inlet is at 1/3 and 2/3 barrel length
Feed inlet.
The cooling roller device includes the first slab roller and the second slab roller that spacing is 180~580 μm, first casting
The diameter of piece roller and the second slab roller ratio is 1:(1~6), first slab roller and the second slab roller rotate towards each other, it is preferable that
The roller linear velocity numerical value of the roller linear velocity of first slab roller and second slab roller 4 is equal.
The drying device includes multiple transfer rollers arranged at broken line, is arranged in the position that film is in contact with transfer roller
Have for dry air gun, the jet direction of the preferably described air gun and the plane tangent of the transfer roller.
To sum up, the pore former that provides according to the present invention and with the lithium ion battery of its resistance to thermal contraction obtained every
Film, the present invention possessed by beneficial effect include:
(1) heretofore described pore former includes organic pore former and Inorganic pore forming agents, preferably can control to form micropore
Size, shape and distribution, be conducive to improve battery diaphragm porosity and venting quality；
(2) lithium ion battery separator made from has good thermal shrinkage, tensile strength, puncture strength, tool simultaneously
There are lower closed pore temperature and higher broken film temperature；
(3) lithium ion battery separator made from has three-decker, and every layer of micro-pore shape, aperture are different, micropore
It is evenly distributed, porosity is high；
(4) each component is from a wealth of sources, low in cost.
Detailed description of the invention
Fig. 1 shows extruder feeding device schematic diagram according to an embodiment of the present invention；
Fig. 2 shows cooling roller device schematic diagrames according to an embodiment of the present invention；
Fig. 3 shows drying device schematic diagram according to an embodiment of the present invention；
Fig. 4 shows the drying mode schematic diagram in traditional processing technology；
Fig. 5 shows the battery diaphragm representative side section view of resistance to thermal contraction according to an embodiment of the present invention.
Drawing reference numeral explanation
1- polyolefin feed inlet
2- pore former feed inlet
The first slab roller of 3-
The second slab roller of 4-
5- extruder die head
6- transfer roller
7- air gun
8- hydraulic giant
The first outer layer of 9-
The second outer layer of 10-
11- internal layer
Specific embodiment
Below by drawings and examples, the present invention is described in more detail.Illustrated by these, the features of the present invention
It will be become more apparent from advantage clear.
According to the present invention, the preparation method for preparing three kinds of microcellular structure battery diaphragms uses specific device, the device packet
Extrusion device, cooling roller device and drying device are included, specific as follows:
Extrusion device
As shown in Figure 1, the extrusion device includes polyethylene composition feed inlet 1 and pore former feed inlet 2.
In a preferred embodiment in accordance with the present invention, the extrusion device preferably includes two polyethylene composition chargings
Mouth 1 and two pore former feed inlets 2.
The extrusion device further includes machine barrel, and described two polyethylene composition feed inlets 1 are juxtaposed on the machine barrel
One end, described two pore former feed inlets 2 be respectively arranged on the machine barrel away from the polyethylene composition feed inlet 1 be 1/
At 3 and 2/3 barrel length.
In a preferred embodiment in accordance with the present invention, polyethylene or combinations thereof object, Inorganic pore forming agents and optional addition
After being pre-mixed uniformly through described two polyethylene composition feed inlets 1 extrusion device is added in agent, preferably by inorganic pore-forming
Agent and high molecular polythene are pre-mixed uniformly, and optional additive and ultra high molecular polyethylene are pre-mixed uniformly, above-mentioned
The extrusion device is added through described two polyethylene composition feed inlets 1 respectively in two kinds of mixtures, is easier to be uniformly mixed.
Said mixture is heated to molten condition in the extrusion device and squeezes out along the machine barrel, in extrusion direction
Organic pore former is added through described two pore former feed inlets 2, melts and squeeze out after mixing casting films, can avoid polyethylene
The appearance of composition and pore former mutually separates and causes mixing uneven and with pressure oscillation in extruder, so that polyethylene composition
It is sufficiently mixed uniformly with pore former, pore former is uniformly distributed in polyethylene composition mixture, is conducive to make in subsequent step
The standby aperture for obtaining micropore and the battery diaphragm being more evenly distributed.
Cooling roller device
As shown in Fig. 2, the cooling roller device includes the first slab roller 3 and the second casting that axis is located in same level
Piece roller 4, the spacing between first slab roller 3 and the second slab roller 4 is 180-580 μm, preferably 230-530 μm, more excellent
It is selected as 280-480 μm.
In a preferred embodiment in accordance with the present invention, 4 opposite direction rotating of first slab roller 3 and the second slab roller, from
The casting films that extruder die head 5 squeezes out form accumulation between the first slab roller 3 and the second slab roller 4, then by the two
Between gap squeeze, be cooling, cast sheet, reduce the factors such as uneven, the extruder machinery concussion of rate of extrusion to sheet character
Influence, to prepare the sheet that thickness is uniform, character is stable.
In a preferred embodiment in accordance with the present invention, the diameter ratio of first slab roller 3 and the second slab roller 4 is 1:
(1~6), preferably 1:(2~5), more preferably 1:(3~4), the diameter of preferably described first slab roller 3 is 300-600mm,
The diameter of second slab roller 4 is 500-900mm.
It is internally provided with cooling device in first slab roller 3 and the second slab roller 4, for controlling the first slab roller
3 and 4 surface of the second slab roller temperature, so that the casting films to extrusion cool down, preferably described first slab roller 3 and second
The temperature of slab roller 4 is 5~40 DEG C, and preferably 10~35 DEG C, more preferably 12~33 DEG C, the casting films of extrusion flow through the first casting
Two-sided cooling and shaping, cast sheet when gap between piece roller 3 and the second slab roller 4, meanwhile, be uniformly distributed inside it at
Hole agent occurs thermotropic phase with polyethylene composition and separates, and the sheet of two-sided cooling closes pore former inside it, with tradition
The cooling sheet of single side is compared in technique, and pore former is less susceptible to ooze out, and aperture, the distribution for being conducive to obtained micropore are more uniform
Battery diaphragm.
In a preferred embodiment in accordance with the present invention, optionally by the surface of first slab roller 3 or the second slab roller 4
It is processed into rough plane, the coarse battery diaphragm of single or double can be prepared, improve membrane surface to other materials
The adhesive force of (such as: coating, film) is laid a good foundation for research and development novel battery diaphragm.
Drying device
As shown in figure 3, the drying device includes multiple transfer rollers 6 arranged at broken line, connect in film with transfer roller 6
The position of touching is provided with for dry air gun 7.
In a preferred embodiment in accordance with the present invention, the surface phase of the jet direction of the air gun 7 and the transfer roller 6
It cuts.
In a preferred embodiment in accordance with the present invention, film extracted advances through multiple transfer rollers 6 along broken line, thin
The position that film is in contact with each transfer roller 6 is provided with for dry air gun 7, to remove the remaining extractant of film surface,
Prevent stain mark, the jet direction of the air gun 7 and the plane tangent of transfer roller, i.e., it is parallel with the direction of transfer of film,
Drying effect is good, and effectively prevents the generation of film surface water ripples, meanwhile, air gun 7 is bright to the vertical impact forces of film
It is aobvious to reduce, significantly improve the finally bad phenomenons such as obtained battery diaphragm appearance fold, scollop, scallop；And in traditional processing technology
In.
It is different from above content of the present invention, as shown in figure 4, film extracted is along linear transmission, and gentle using hydraulic giant 8
The mixing of rifle 7 is dried, and water ripples easily occurs in film surface obtained, cause final obtained battery diaphragm uneven thickness or
Injustice, and hydraulic giant 8 and air gun 7 inject directly on the surface of film at a certain angle, impact force is big, battery diaphragm appearance pleat
Phenomena such as wrinkle, scollop, scallop, is serious, influences using and winding for battery diaphragm.
In another embodiment according to the present invention, as shown in figure 5, the battery diaphragm of the resistance to thermal contraction includes the
One outer layer 9, the second outer layer 10 and it is clipped in internal layer 11 between the two, first outer layer 9, the second outer layer 10 and internal layer 11 have
Different microcellular structures.
The aperture of first outer layer 9 is 20~100nm, and the aperture of the second outer layer 10 is 30~140nm, the hole of internal layer 11
Diameter is 50~180nm.
Embodiment
Embodiment 1
The polyethylene composition for being used to prepare the lithium ion battery separator of resistance to thermal contraction includes the component of following weight proportion:
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 average molecular weight of white oil is 200,
The partial size of the nanometer magnesium chloride is 50~70nm.
Lithium ion battery separator is made in above-mentioned composition in accordance with the following methods:
Step 1) squeezes out: by high molecular polythene and nanometer magnesium chloride melting mixing, being added and is squeezed out by first charging aperture
Machine, by ultra high molecular polyethylene, 4,4- thiobis (6- tert-butyl-m-cresol), 2,4-DihydroxyBenzophenone, octadecyl season
Extruder is added by second charging aperture in ammonium sodium and Tween 80, by white oil by the first pore former feed inlet and the second pore former feed inlet
Extruder is added, is 210~240 DEG C in extrusion temperature, rate of extrusion squeezes above-mentioned composition under conditions of being 1200g/min
Out, casting films are formed；
Step 2), slab: the casting films that step 1) is extruded into flow through the first slab roller (3), and (surface is smooth, surface temperature
Be 20 DEG C) and the second slab roller (4) (surface is smooth, surface temperature be 20 DEG C) between gap, cast the thickness with a thickness of 400 μm
Piece；
Step 3), longitudinal stretching: the sheet that step 2) obtains successively preheated roller (surface temperature is 80 DEG C), draw roll
(every grade of ratio of elongation is 6, and surface temperature is 110 DEG C) and chill roll (surface temperature is 20 DEG C) carry out longitudinal stretching；
Step 4), first time cross directional stretch: the two sides of the film that step 3) obtains in the direction of the width are individually fixed in folder
Hold in mechanism, successively through the first preheating zone (surface temperature is 100 DEG C), (every grade of ratio of elongation is 7 to the first drawing zone, surface
Temperature is 115 DEG C) and when the first cooling zone (surface temperature is 95 DEG C), lateral drawing is carried out under the action of the clamping device
It stretches；
Step 5), extraction: (methylene chloride and trimethyl phosphate are by weight through the first extractant for the film that step 4) obtains
The mixture of 22:1 composition) and the second extractant (high purity water) immersion 6h, it is then dried with air gun, obtains film；
Step 6), second of cross directional stretch: the two sides of the film that step 5) obtains in the direction of the width are individually fixed in folder
Hold in mechanism, successively through the second preheating zone (surface temperature is 115 DEG C), (every grade of ratio of elongation is 1.2 to the second drawing zone, surface
Temperature is 125 DEG C) and second of cross directional stretch of the second cooling zone (surface temperature is 95 DEG C) progress, it obtains resistance to a thickness of 16.2 μm
The battery diaphragm of thermal contraction.
Embodiment 2
The composition for being used to prepare lithium ion battery separator includes the component of following weight proportion:
Wherein,
The number-average molecular weight of high molecular polythene is 300,000.
The number-average molecular weight that ultra high molecular polyethylene is is 1,300,000.
The average molecular weight of white oil is 180；
The partial size of nanometer magnesium chloride is 60~90nm.
Above-mentioned composition is prepared into lithium ion battery separator in accordance with the following methods:
Step 1) squeezes out: by high molecular polythene and nanometer magnesium chloride melting mixing, being added and is squeezed out by first charging aperture
Machine, by ultra high molecular polyethylene, 3,5-di-tert-butyl-4-hydroxytoluene, 4- benzoyloxy -2,2,6,6- tetramethyl piperidines,
Extruder is added by second charging aperture in octadecyl quaternary ammonium sodium and lauric acid, by white oil by the first pore former feed inlet and the second one-tenth
Hole agent feed inlet is separately added into extruder, is 210~240 DEG C in extrusion temperature, and rate of extrusion will under conditions of being 1200g/min
Above-mentioned composition squeezes out, and forms casting films；
Step 2), slab: the casting films that step 1) is extruded into flow through the first slab roller (3) (surface roughness 0.1,
Surface temperature is 20 DEG C) and the second slab roller (4) (surface roughness 0.2, surface temperature be 20 DEG C) between gap, cast
With a thickness of 400 μm of sheet；
Step 3), longitudinal stretching: the sheet that step 2) obtains successively preheated roller (surface temperature is 80 DEG C), draw roll
(every grade of ratio of elongation is 6, and surface temperature is 110 DEG C) and chill roll (surface temperature is 20 DEG C) carry out longitudinal stretching；
Step 4), first time cross directional stretch: the two sides of the film that step 3) obtains in the direction of the width are individually fixed in folder
Hold in mechanism, successively through the first preheating zone (surface temperature is 100 DEG C), (every grade of ratio of elongation is 7 to the first drawing zone, surface
Temperature is 115 DEG C) and when the first cooling zone (surface temperature is 95 DEG C), lateral drawing is carried out under the action of the clamping device
It stretches, obtains film；
Step 5), extraction: (methylene chloride and trimethyl phosphate are by weight through the first extractant for the film that step 4) obtains
The mixture of 22:1 composition) and the second extractant (high purity water) immersion 6h, it is then dried with air gun, obtains film；
Step 6), second of cross directional stretch: the two sides of the film that step 5) obtains in the direction of the width are individually fixed in folder
Hold in mechanism, successively through the second preheating zone (surface temperature is 115 DEG C), (every grade of ratio of elongation is 1.2 to the second drawing zone, surface
Temperature is 125 DEG C) and second of cross directional stretch of the second cooling zone (surface temperature is 95 DEG C) progress, it obtains resistance to a thickness of 16.2 μm
The battery diaphragm of thermal contraction.
Embodiment 3
The present embodiment method therefor is similar to 2 method therefor of embodiment, and difference is only that polyethylene composition includes following
The component of weight proportion:
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 is identical as 1 method therefor of embodiment, and difference, which is only that in polyethylene composition, is added without white oil.
Battery diaphragm micropore size obtained is excessive, and uneven, the cracky when preparing lithium ion battery.
Comparative example 2
Using the preparation method of battery diaphragm described in embodiment 6 in patent CN201210454073.9, it may be assumed that by the equal molecule of number
Amount is that the polyethylene of 800,000 g/mol is heated to 180 DEG C of meltings, is added in double screw extruder with 54kg/h feed rate.It will be white
Oil is heated to 95 DEG C, and 3h is mixed with 2,6- di-tert-butyl-4-methy phenol, mixture is injected twin-screw extrusion in two times
In machine.Temperature inside extruder is 200 DEG C, and extrusion temperature is 190 DEG C, and extruded material is through between 15 DEG C of chill rolls and adjustable roller
Gap squeeze and cast sheet with a thickness of 1.4mm.The mass ratio of polyethylene and white oil is 1:2.4,2,6- di-t-butyl -4- first
The quality of base phenol is the 1.0% of white oil quality.
Sheet obtained above is successively subjected to longitudinal stretching and first time cross directional stretch, the temperature of longitudinal stretching is 100
DEG C, stretching ratio 5.78, temperature stretching in the transverse direction is 120 DEG C for the first time, and stretching ratio 4.41 is extracted through methylene chloride
Afterwards, medial septum is obtained.
Medial septum obtained above is subjected to second of cross directional stretch, second of temperature stretching in the transverse direction is 132 DEG C, is drawn
Stretching multiplying power is 1.6, and winding cutting, 50 DEG C of ageing treatment 18h obtain battery diaphragm.
Experimental example
Battery diaphragm made from Examples 1 to 3 and comparative example 1 and 2 is tested as follows, test result is shown in Table 1:
(1) thickness of battery diaphragm is measured；
(2) using the microcellular structure of electronic scanner microscope observation battery diaphragm, and aperture is measured；
(3) using the porosity of press pump instrument measurement battery diaphragm；
(4) using the venting quality of venting quality tester measurement battery diaphragm；
(5) using the longitudinal tensile strength and transverse tensile strength of tension tester measurement battery diaphragm；
(6) using the puncture strength of electronic tensile machine measurement battery diaphragm, longitudinal elongation percentage and it is laterally extended rate；
(7) it is heat-shrinked using longitudinal percent thermal shrinkage of battery diaphragm percent thermal shrinkage tester measurement battery diaphragm and laterally
Rate；
(8) using battery septum closed pore temperature and the closed pore temperature and rupture of membranes temperature of broken film temperature tester measurement battery diaphragm
Degree.
1. battery diaphragm the performance test results of table
Preferred embodiment, embodiment and comparative example is combined to describe the invention in detail above.But need sound
Bright, these specific embodiments are only that illustrative explanations of the invention do not constitute protection scope of the present invention and appointed
What is limited.It, can be to the technology of the present invention content and embodiments thereof without departing from spirit of that invention and protection scope
Various improvement, equivalencing or modification are carried out, these fall within the protection scope of the present invention.Protection scope of the present invention is with institute
Subject to attached claim.
Claims (10)
1. the purposes that a kind of pore former combination object is used to prepare the lithium ion battery separator of resistance to thermal contraction, which is characterized in that the group
Closing object includes organic pore former and Inorganic pore forming agents,
The organic pore former is selected from higher boiling small organic molecule；The Inorganic pore forming agents are selected from water-soluble inorganic nanometer
Grain；
The higher boiling small organic molecule is that boiling point is higher than 200 DEG C, and liquid state organics of the number-average molecular weight less than 500；
The water-soluble inorganic nano particle is the particles of inorganic material that partial size is 1 ~ 200nm；
The organic pore former and the weight ratio of the Inorganic pore forming agents are (30 ~ 60): (1 ~ 10)；The pore former is added to poly-
In alkene, be 100 parts by weight by the weight of polyolefin in terms of, the additional amount of pore former is 20 ~ 70 parts by weight；
In battery diaphragm preparation process, the pore former is added portionwise in polyolefin: polyethylene composition, Inorganic pore forming agents are pre-
Extruder is put into through polyethylene composition feed inlet after being first uniformly mixed, then heating melting, the extruder further include machine barrel,
Pore former feed inlet is set on the machine barrel, by pore former on the extrusion direction of the polyethylene composition of extruder inner molten
Organic pore former is added in feed inlet, melts and squeezes out casting films after mixing.
2. purposes according to claim 1, which is characterized in that the higher boiling small organic molecule is selected from mineral oil, C6-15Alkane
Hydrocarbon, C8-15Aliphatic carboxylic acid, C1-4Alkyl ester, C2-6One of halogenated alkane is a variety of,
The water-soluble inorganic nano particle is selected from water-soluble nano sulfate, water-soluble nano nitrate, water-soluble nano salt
One of hydrochlorate is a variety of.
3. purposes according to claim 2, which is characterized in that the mineral oil is white oil；The C6-15Alkane is selected from heptane, naphthalene
Alkane, decane, hendecane and dodecane；The C8-15Aliphatic carboxylic acid is selected from capric acid, hendecoic acid and lauric acid；The C1-4Alkane
Ester is selected from methyl caprate, ethyl caprate, capric acid propyl ester, capric acid N-butyl, hendecoic acid methyl esters, hendecoic acid ethyl ester, 11 carbon
Propyl propionate, hendecoic acid N-butyl, lauric acid methyl esters, dodecanoate, lauric acid propyl ester, lauric acid N-butyl；
The C2-6Halogenated alkane is selected from dichloroethanes, dichloropropane, chlorofluoroethane and fluorine chloropropane；
The water-soluble nano sulfate is selected from nanometer sodium sulphate, nanometer potassium sulfate and nanometer ammonium sulfate；The water-soluble nano
Nitrate is selected from nanometer sodium nitrate, nanometer potassium nitrate, nanometer ammonium nitrate, nanometer magnesium nitrate and nanometer copper nitrate；The water solubility
Nanometer hydrochloride is selected from nanometer sodium chloride, nanometer potassium chloride, nanometer ammonium chloride, nanometer magnesium chloride, nanometer calcium chloride and nanometer chlorine
Change copper.
4. purposes according to claim 1, which is characterized in that the weight of the organic pore former and the Inorganic pore forming agents
Than for (35 ~ 55): (2 ~ 8).
5. purposes according to claim 4, which is characterized in that the weight of the organic pore former and the Inorganic pore forming agents
Than for (40 ~ 50): (4 ~ 6).
6. purposes according to claim 1, which is characterized in that the organic pore former is white oil, the Inorganic pore forming agents
For nanometer magnesium chloride, the pore former is the composition of white oil and nanometer magnesium chloride.
7. purposes according to claim 1, which is characterized in that by the weight of polyolefin be 100 parts by weight in terms of, pore former
Additional amount is 30 ~ 60 parts by weight.
8. purposes according to claim 7, which is characterized in that by the weight of polyolefin be 100 parts by weight in terms of, pore former
Additional amount is 50 parts by weight.
9. a kind of preparation method of the lithium ion battery separator of resistance to thermal contraction, which is characterized in that this method comprises:
Step 1), other additives melting by the pore former combination object in polyethylene or combinations thereof object, claim 1 and optionally
Mixing squeezes out casting films；
Step 2, the casting films that step 1) squeezes out flow through the gap between the first slab roller and the second slab roller, cast sheet；
Step 3), successively preheated roller, draw roll and chill roll carry out longitudinal stretching to the sheet that step 2 obtains；
Step 4), the film two sides that step 3) obtains are fixed, successively through the first preheating zone, the first drawing zone and the first cooling zone into
Row cross directional stretch；
Step 5), the film that step 4) obtains are handled through extractant, are then dried；The drying carries out in drying device, institute
Stating drying device includes multiple transfer rollers arranged at broken line, is provided in the position that film is in contact with transfer roller for drying
Air gun, the jet direction of the air gun and the plane tangent of the transfer roller or parallel with the direction of transfer of film；
Step 6), the film two sides that step 5) obtains are fixed, successively through the second preheating zone, the second drawing zone and the second cooling zone into
Second of cross directional stretch of row, obtains the battery diaphragm of resistance to thermal contraction.
10. preparation method according to claim 9, which is characterized in that the battery diaphragm of the resistance to thermal contraction of preparation includes the
One outer layer, the second outer layer and it is clipped in internal layer between the two, first outer layer, the second outer layer and internal layer have different micropores
Structure,
The average pore size of first outer layer is 20 ~ 100 nm, and the average pore size of the second outer layer is 30 ~ 140 nm, the hole of internal layer
Diameter is 50 ~ 180 nm.
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|---|---|---|---|---|
| CN101267934A (en) * | 2005-09-22 | 2008-09-17 | 三菱树脂株式会社 | Perforated laminate and its manufacturing method |
| CN102208588A (en) * | 2010-12-30 | 2011-10-05 | 上海恩捷新材料科技股份有限公司 | Battery insulation film |
| CN102931371A (en) * | 2012-11-13 | 2013-02-13 | 辽源鸿图锂电隔膜科技股份有限公司 | Battery diaphragm preparation method |
| CN103618054A (en) * | 2013-11-08 | 2014-03-05 | 青岛中科华联新材料有限公司 | Novel high-temperature-resisting diaphragm of lithium battery and preparation process of diaphragm |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101267934A (en) * | 2005-09-22 | 2008-09-17 | 三菱树脂株式会社 | Perforated laminate and its manufacturing method |
| CN102208588A (en) * | 2010-12-30 | 2011-10-05 | 上海恩捷新材料科技股份有限公司 | Battery insulation film |
| CN102931371A (en) * | 2012-11-13 | 2013-02-13 | 辽源鸿图锂电隔膜科技股份有限公司 | Battery diaphragm preparation method |
| CN103618054A (en) * | 2013-11-08 | 2014-03-05 | 青岛中科华联新材料有限公司 | Novel high-temperature-resisting diaphragm of lithium battery and preparation process of diaphragm |
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