CN109546059A - A kind of diaphragm for non-water system secondary battery and preparation method thereof - Google Patents
A kind of diaphragm for non-water system secondary battery and preparation method thereof Download PDFInfo
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- CN109546059A CN109546059A CN201811203510.3A CN201811203510A CN109546059A CN 109546059 A CN109546059 A CN 109546059A CN 201811203510 A CN201811203510 A CN 201811203510A CN 109546059 A CN109546059 A CN 109546059A
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- diaphragm
- secondary battery
- water system
- system secondary
- hexafluoropropylene copolymer
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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
- 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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- 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
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Abstract
The present invention provides a kind of diaphragm for non-water system secondary battery and preparation method thereof, the porous layer that the diaphragm includes at least microporous membrane and is set to a microporous membrane at least side surface；Wherein, the porous layer includes vinylidene fluoride-hexafluoropropylene copolymer and sodium carboxymethylcellulose, and the vinylidene fluoride-hexafluoropropylene copolymer has monomeric unit and hexafluoropropene monomeric unit containing hydrophilic radical.When vinylidene fluoride-hexafluoropropylene copolymer of the invention provides dry cementability and it is wet when cementability, sodium carboxymethylcellulose effectively can inhibit porous layer to be excessively swollen, apparent deterioration will not occur with the recycling of battery for cementability when guaranteeing wet, to guarantee the excellent performance of battery.
Description
Technical field
The present invention relates to lithium ion battery separator technical field, more particularly to a kind of diaphragm for non-water system secondary battery and
Preparation method.
Background technique
In recent years, non-aqueous electrolyte secondary battery especially lithium ion secondary battery be no longer limited to be used in mobile phone,
The miniaturized electronics such as portable data assistance, people, which are desirable to it, can be used for large flat computer, grass trimmer, electric two-wheel
The large scale equipments such as vehicle, electric car, hybrid vehicle, power bus, ship, therefore, the enlargement of battery has to be developed.
In the prior art, acquisition can be prepared in the structure of battery: anode electrode and negative electrode are laminated across diaphragm
Obtained from electrode body or winding obtained from electrode body (rolled electrode bodies) cylinder battery；By the rolled electrode bodies into
Soft-package battery obtained from row is press-formed and is coated with laminate housing body；It is embedded in square obtained from rectangular outer package jar
Battery.
Due to battery enlargement and cause the electrode in the manufacturing process of electrode body active material face and diaphragm it is viscous
It when connecing insufficient, might have following such problems: generating gap to which flexure, deformation, Wu Fashou occur for rolled electrode bodies
It receives into specified volume.Obstacle is caused to the conveying of electrode body as a result, or causes to be difficult to be embedded in external packing body, there are lifes
The misgivings that yield is substantially reduced.In addition, even if above-mentioned gap is still maintained after being filled with electrolyte, electrode and diaphragm it is viscous
Connecing becomes uneven, and circulating battery characteristic reduces.And battery is more enlarged, and the above problem can be increasingly severe.
Therefore, in order to prevent the bending or deformation of electrode body, improve productivity or battery performance, in the manufacture work of electrode body
In sequence, it is desirable that when electrolyte does not soak, enhance the cementability (cementability when dry) of diaphragm and electrode.But if in order to ensure
Cementability when dry and carry out hot pressing using excessive bonding composition or under the conditions of excessively between diaphragm and electrode
It connects, then the air permeability of diaphragm can be made to deteriorate.The binding function of adaptation also can be by between electrode when moreover, for keeping wet
To damage.Thus, it is extremely difficult to while cementability and cementability when drying when realizing wet.
For battery separator, it is desirable that mechanical strength with higher, heat resistance, ion permeability, hole occlusion are special
Property (closing property, shutdown), melting rupture of membranes characteristic (pre-arcing characterisitics, meltdown) etc..Therefore, so far, right
Be provided with multiple aperture plasma membrane and positioned at its surface porous layer battery separator using being studied.But this structure
Diaphragm there are following problems: the part at the interface of diaphragm and electrode is free, and (it is by the bumps of electrode surface or charge and discharge institute companion
With electrode expansion/contraction caused by) cause battery internal resistance increase, circulating battery characteristic reduce.
Therefore, the present invention provides a kind of diaphragm for non-water system secondary battery and preparation method thereof, moistens diaphragm in electrolyte
In wet and non-wetted situation, there is stronger caking property with electrode.
Summary of the invention
In view of the foregoing deficiencies of prior art, the purpose of the present invention is to provide a kind of non-aqueous secondary battery with every
Film and preparation method thereof, bonding when leading to wet because being constantly swollen in battery use process for solving prior art septation
Property gradually weaken and battery internal resistance increase, circulating battery characteristic reduce the problem of.
In order to achieve the above objects and other related objects, the present invention provides a kind of diaphragm for non-water system secondary battery, described
The porous layer that diaphragm includes at least microporous membrane and is set to a microporous membrane at least side surface；
Wherein, the porous layer includes vinylidene fluoride-hexafluoropropylene copolymer and sodium carboxymethylcellulose, the inclined fluorine
Ethylene-hexafluoropropylene copolymer has monomeric unit and hexafluoropropene monomeric unit containing hydrophilic radical.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the monomer list containing hydrophilic radical
Member is in the molar content in the vinylidene fluoride-hexafluoropropylene copolymer between 0.1 mole of % to 5 moles of %.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the monomer list containing hydrophilic radical
Member is including in maleic anhydride monomer units, maleic acid monomer units, maleate monomer unit, monomethyl maleate monomeric unit
It is one or more.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the hexafluoropropene monomeric unit exist
Molar content in the vinylidene fluoride-hexafluoropropylene copolymer is between 0.3 mole of % to 3 moles of %.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the biasfluoroethylene-hexafluoropropylene
The matter average molecular weight of copolymer is between 500,000~2,000,000.
The scheme of a kind of optimization as diaphragm for non-water system secondary battery of the present invention, by the vinylidene-hexafluoro third
The gross mass meter of alkene copolymer and the sodium carboxymethylcellulose, the content of the sodium carboxymethylcellulose is between 0.5 mass %
To between 10 mass %.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the porous layer also include grain
Son.
The scheme of a kind of optimization as diaphragm for non-water system secondary battery of the present invention, by the vinylidene-hexafluoro third
The gross mass meter of alkene copolymer, the sodium carboxymethylcellulose and the particle, the content of the particle between 20 mass % extremely
Between 85 mass %.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the particle include aluminium oxide, two
One of titanium oxide and boehmite are a variety of.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the average grain diameter of the particle between
Between 0.3 μm~3.0 μm.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the porous layer of every single side
Thickness is between 0.5 μm~4 μm.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the diaphragm it is wet when bending it is strong
Degree in 14N or more, the drying of the diaphragm bending strength in 7N or more.
A kind of scheme of optimization as diaphragm for non-water system secondary battery of the present invention, the microporous membrane include polyolefin
Microporous membrane.
The present invention also provides a kind of preparation method of diaphragm for non-water system secondary battery, the preparation method is included at least:
(a) vinylidene fluoride-hexafluoropropylene copolymer is dissolved in solvent, obtains fluororesin solution；
(b) carboxymethylcellulose sodium solution is added in the fluororesin solution, is mixed to get coating fluid；
(c) microporous membrane is provided, the coating fluid is coated on to an at least side surface for the microporous membrane, then be impregnated in
It in coagulating bath, cleaned, dried later, obtain the diaphragm.
A kind of scheme of optimization of preparation method as diaphragm for non-water system secondary battery of the present invention, the inclined fluorine second
Alkene-hexafluoropropylene copolymer preparation method includes: by ion exchange water, the monomer containing hydrophilic radical, vinylidene and hexafluoro
Propylene is put into autoclave, carries out suspension polymerisation, is obtained polymer paste, is later dehydrated the polymer paste, water
It washes and dries, to obtain vinylidene fluoride-hexafluoropropylene copolymer.
A kind of scheme of optimization of preparation method as diaphragm for non-water system secondary battery of the present invention will in step (a)
Vinylidene fluoride-hexafluoropropylene copolymer is dissolved in solvent and stirs, and particle is added in stirring while, obtains the fluorine for being dispersed with particle
Resin solution.
As described above, diaphragm for non-water system secondary battery and preparation method thereof of the invention, has the advantages that
It 1, include vinylidene fluoride-hexafluoropropylene copolymer in porous layer of the invention, and biasfluoroethylene-hexafluoropropylene is total
There is the monomeric unit containing hydrophilic radical, therefore, porous layer can be with the active material, the electrode that are present in electrode surface in polymers
In adhesive ingredients hydrophilic radical between interact, can be bonded securely.
2, the compatibility of the vinylidene fluoride-hexafluoropropylene copolymer and nonaqueous electrolytic solution contained in porous layer of the invention
Height, and it is also high to the chemical stability of nonaqueous electrolytic solution, physical stability.Therefore, the porous layer containing the copolymer is presented
Cementability good feature when moistening out can sufficiently keep the compatibility with electrolyte when use at high temperature.
3, include sodium carboxymethylcellulose in porous layer of the invention, effectively porous layer can be inhibited excessively to be swollen, protect
Apparent deterioration will not occur with the recycling of battery for cementability when card is wet, to guarantee the excellent performance of battery.
4, the present invention be capable of providing will not make vapour lock degree deteriorate and meanwhile when realizing dry cementability and it is wet when cementability
Battery separator, which is applied to battery, the good circulation performance of battery can be kept, particularly suitable for winding-type large-scale electricity
Pond.
Detailed description of the invention
Fig. 1 is the flow diagram of the preparation method of diaphragm for non-water system secondary battery of the present invention.
Fig. 2 is the structural schematic diagram of bending strength when present invention measurement diaphragm is wet.
Fig. 3 is the structural schematic diagram of bending strength when present invention measurement diaphragm is dry.
Component label instructions
1 cathode
2 diaphragms
3 pressure heads aluminum L shape angle section
4 aluminum L shape angle sections
5 laminated films
Specific embodiment
Illustrate embodiments of the present invention below by way of specific specific example, those skilled in the art can be by this specification
Other advantages and efficacy of the present invention can be easily understood for disclosed content.The present invention can also pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also based on different viewpoints and application, without departing from
Various modifications or alterations are carried out under spirit of the invention.
Please refer to attached drawing.It should be noted that only the invention is illustrated in a schematic way for diagram provided in the present embodiment
Basic conception, only shown in schema then with related component in the present invention rather than component count, shape when according to actual implementation
Shape and size are drawn, when actual implementation kenel, quantity and the ratio of each component can arbitrarily change for one kind, and its component cloth
Office's kenel may also be increasingly complex.
The present invention provides a kind of diaphragm for non-water system secondary battery, and the diaphragm includes at least microporous membrane and is set to institute
State the porous layer of a microporous membrane at least side surface；
Wherein, the porous layer includes vinylidene fluoride-hexafluoropropylene copolymer and sodium carboxymethylcellulose, the inclined fluorine
Ethylene-hexafluoropropylene copolymer has monomeric unit and hexafluoropropene monomeric unit containing hydrophilic radical.
It should be noted that the application is to provide following battery separators as target, the battery separator will not make gas
Resistance degree deteriorate, also, be able in the future the battery developed enlargement brought by new issue i.e. dry when cementability and it is wet when
It is excellent in adhesion, and it is wet when cementability will not be recycled with the use of battery after apparent deterioration occurs.It needs to illustrate again
, in this specification, cementability when so-called wet refers to the viscous of diaphragm in the state that diaphragm includes electrolyte and electrode
Connecing property, with using aftermentioned measuring method obtain it is wet when bending strength indicate.In addition, cementability when so-called dry, refers to
The cementability of diaphragm and electrode in the state that diaphragm does not substantially contain electrolyte, it is dry to be obtained using aftermentioned measuring method
Bending strength indicates when dry.
Below in diaphragm for non-water system secondary battery of the invention microporous membrane and porous layer illustrate its summary, when
So it is not limited to these typical examples.
1. microporous membrane
In the present invention, microporous membrane refers to the film in the internal gap for having and being connected.As microporous membrane, do not limit especially
It is fixed, the microporous membrane comprising polyolefin resin can be used.Hereinafter, being the feelings of polyolefin resin to the resin for constituting microporous membrane
Condition is described in detail, and but not limited to this.
[1] polyolefin resin
The polyolefin resin of polyolefin micro porous polyolefin membrane is constituted using polyvinyl resin as principal component.By total matter of polyolefin resin
When amount is as 100 mass %, the content of polyvinyl resin is preferably 80 mass % or more, more preferably 90 mass % or more, into
One step is preferably 100 mass %.
As polyolefin resin, can enumerate by ethylene, propylene, 1- butylene, 4-methyl-1-pentene, 1- hexene etc. polymerization and
Obtained homopolymer, two-step polymerization object, copolymer or their mixture etc..Within the scope of the effect of the invention,
The various additives such as antioxidant, inorganic filler can be added in polyolefin resin as needed.
[2] manufacturing method of polyolefin micro porous polyolefin membrane
As the manufacturing method of polyolefin micro porous polyolefin membrane, as long as it is micro- porous to manufacture the polyolefin with desired characteristic
Film is not particularly limited, and previously known method can be used.Specifically, it is preferable that include following processes (1)~process (5),
Also it may further include following processes (6)~process (8).
Said polyolefins resin and film forming are carried out melting mixing with solvent, manufacture polyolefin solution by process (1)；
Said polyolefins solution is squeezed out and is cooled down by process (2), forms gel-like sheet；
Process (3), the first stretching process stretch above-mentioned gel-like sheet；
Process (4) removes film forming solvent from the gel-like sheet after above-mentioned stretching；
Above-mentioned removing film forming is dried with the sheet material after solvent for process (5)；
Process (6), the second stretching process stretch the sheet material after above-mentioned drying；
Process (7), is heat-treated the sheet material after above-mentioned drying；
Process (8) carries out crosslinking Treatment and/or hydrophilicity-imparting treatment to the sheet material after above-mentioned stretching process.
Hereinafter, being illustrated respectively to each process.
(1) preparation section of polyolefin solution
After adding respectively suitable film forming solvent in polyolefin resin, melting mixing is carried out, polyolefin solution is prepared.
As melting mixing method, the method that double screw extruder can be used.Due to melting mixing method be it is known, because
This is omitted the description.
In polyolefin solution, the mixing ratio of polyolefin resin and film forming solvent is not particularly limited, relative to 20~
For 40 mass parts polyolefin resins, film forming solvent is preferably 60~80 mass parts.If the ratio of polyolefin resin is in above-mentioned model
In enclosing, then when squeezing out polyolefin solution, it can prevent from expanding at die head exit, inside contract, extrusion molding can be made
The mouldability and self-sustainance of body (gel formed body) are good.
(2) formation process of gel-like sheet
Polyolefin solution is supplied from extruder to die head, slabbing is squeezed out.It can also be by the more of identical or different composition
Kind polyolefin solution is supplied from extruder to a die head, is laminated for stratiform here, squeezes out slabbing.
Extrusion method can be any one of flat-die method and inflation method.Extrusion temperature is preferably 140~250 DEG C, is squeezed out
Speed is preferably 0.2~15m/ minutes.Film thickness can be adjusted by adjusting the respective extrusion output of polyolefin solution.
Gel-like sheet is formed by being cooled down to obtained extrusion molding body.It is preferred that with 50 DEG C/min or more
Speed is cooled at least gelling temperature.It is preferably cooled to 25 DEG C or less.By cooling, can will be separated by forming a film with solvent
The microfacies of polyolefin immobilize.If cooling velocity is within the above range, crystallinity is maintained at appropriate range, becomes
Gel-like sheet suitable for stretching.As cooling means, can be used with the method for the refrigerant contacts such as cold wind, cooling water, with
The method etc. of chill roll contact, is preferably allowed to cool with being contacted using refrigerant roller after cooling.
(3) first stretching process
Then, obtained gel-like sheet is at least stretched along uniaxial direction.Since gel-like sheet includes film forming
With solvent, therefore can be evenly stretched.Preferably, tentering method, roller method, inflation method or these methods are utilized after the heating
Combination, stretches gel-like sheet with defined multiplying power.Stretching can be to be uniaxially stretched, or it is biaxial stretch-formed, but
It is preferably biaxial stretch-formed.In the case where biaxial stretch-formed, can for simultaneously biaxial drawing, gradually stretch and multistage stretching (for example,
Any one of simultaneously biaxial drawing and the combination gradually stretched).
Stretching ratio (area stretch multiplying power) in this process is preferably 4 times or more, more preferably 16 times or more, especially excellent
It is selected as 25 times or more.In addition, stretching ratio in mechanical direction (MD) and width direction (TD) each other can be identical or not
Together.It should be noted that the stretching ratio in this process refers to, on the basis of the microporous membrane before it will carry out this process,
It will be for the area stretch multiplying power of the microporous membrane before subsequent processing.
The draft temperature of this process is preferably set to the range of the crystal dispersion temperature (Tcd) of polyolefin resin~Tcd+30 DEG C
It is interior, it is more preferably set as in the range of+28 DEG C of crystal dispersion temperature (Tcd)+5 DEG C~crystal dispersion temperature (Tcd), particularly preferably sets
In the range of Tcd+10 DEG C~Tcd+26 DEG C.For example, draft temperature is preferably set as 90~140 DEG C in the case where polyethylene,
More preferably it is set as 100~130 DEG C.Crystal dispersion temperature (Tcd) utilizes the dynamic viscoelastic according to ASTM D4065
Temperature characterisitic measurement and find out.
By above-mentioned stretching, polythene strip interlayer generates cracking, and polyethylene is mutually miniaturize, and forms a large amount of fibrinogens
(fibril).Fibrinogen forms the three-dimensional reticular structure irregularly linked.By stretching, pore while improving mechanical strength
Expand, if but stretched under suitable conditions, it can control through aperture, there is high hole thinner film thickness is made
Gap rate.
Can also as expected physical property, set temperature distribution is on film thickness direction to be stretched, and this makes it possible to obtain machines
The microporous membrane of tool excellent strength.
(4) the film forming removing of solvent
Using cleaning solvent, the removing (cleaning) of film forming solvent is carried out.Since polyolefin phase is mutually sent out with film forming with solvent
It is raw mutually to separate, it is therefore, available to be formed by fibrinogen (it forms fine tridimensional network) if removing film forming solvent
, the multiple aperture plasma membrane in hole (gap) being irregularly connected to three-dimensional.Film forming is removed due to cleaning solvent and using cleaning solvent
Be with the method for solvent it is known, and the description is omitted.
(5) dry
Using heat drying method or aeration drying, it is dried to film forming is removed with the microporous membrane after solvent.Drying temperature
Preferably the crystal dispersion temperature (Tcd) of polyolefin resin is hereinafter, particularly preferably 5 DEG C lower than Tcd or more.Using microporous membrane as
100 mass % (dry mass) are dry to preferably occur in remaining cleaning solvent as 5 mass % hereinafter, more preferably carrying out to remaining
Cleaning solvent is 3 mass % or less.If remaining cleaning solvent is within the above range, the microporous membrane of follow-up phase is being carried out
When stretching process and heat treatment procedure, it is able to maintain the porosity of microporous membrane, permeability is inhibited to deteriorate.
(6) second stretching process
It is preferred that at least being stretched along uniaxial direction to the microporous membrane after drying.It can with while heating above-mentioned same
Sample microporous membrane is stretched using tentering method etc..Stretching can be to be uniaxially stretched, or biaxial stretch-formed.In twin shaft
Any one of in the case where stretching, can be stretched for simultaneously biaxial drawing and gradually.Draft temperature in this process is without spy
It does not limit, it is often preferred that 90~135 DEG C, more preferably 95~130 DEG C.
For the stretching ratio (area stretch multiplying power) that microporous membrane in this process is stretched on uniaxial direction,
In the case where being uniaxially stretched, 1.0~2.0 times are set as in mechanical direction or width direction.In the case where biaxial stretch-formed, area
The lower limit value of stretching ratio is preferably 1.0 times or more, more preferably 1.1 times or more, further preferably 1.2 times or more.The upper limit
Preferably 3.5 times or less of value.1.0~2.0 times are respectively set as in mechanical direction and width direction, in mechanical direction and width direction
Stretching ratio may be the same or different each other.It should be noted that the stretching ratio in this process refers to, with will
On the basis of carrying out the microporous membrane before this process, i.e., by the stretching ratio for the microporous membrane before subsequent processing.
(7) it is heat-treated
Furthermore it is possible to be heat-treated to the microporous membrane after drying.By heat treatment, being stabilized, lamella are crystallized
It is homogenized.As heat treatment method, thermal finalization processing and/or hot wire-CVD processing can be used.Thermal finalization, which is handled, to be referred to,
Keep the heat treatment heated while film size constancy.Hot wire-CVD processing refers to, make film in mechanical direction in heating or
The heat treatment being heat-shrinked in width direction.Thermal finalization processing is carried out preferably by stenter mode or roller mode.Heat treatment temperature
It is preferred that in the range of Tcd~Tm of polyolefin resin, more preferably in the range of draft temperature ± 5 DEG C of microporous membrane, especially
It is preferably in the range of the second draft temperature ± 3 DEG C of microporous membrane.
(8) crosslinking Treatment, hydrophilicity-imparting treatment
Alternatively, it is also possible to the microporous membrane further progress crosslinking Treatment and hydrophilicity-imparting treatment after engagement or after stretching.
For example, thus being carried out at crosslinking by irradiating the ionizing radiations such as alpha ray, β ray, gamma-rays, electron beam to microporous membrane
Reason.In the case where irradiating electron beam, electron beam amount is preferably 0.1~100Mrad, and acceleration voltage is preferably 100~300kV.
By crosslinking Treatment, the fusion temperature of microporous membrane rises.In addition, at using monomer grafting, surfactant
Reason, corona discharge etc. carry out hydrophilicity-imparting treatment.Monomer grafting carries out preferably after crosslinking Treatment.
2. porous layer
Porous layer possessed by battery separator of the invention includes vinylidene fluoride-hexafluoropropylene copolymer and carboxymethyl
Sodium cellulosate.Thus, it is possible to simultaneously realize dry when cementability and it is wet when cementability.
[1] biasfluoroethylene-hexafluoropropylene (VdF-HFP) copolymer
The compatibility of vinylidene fluoride-hexafluoropropylene copolymer and nonaqueous electrolytic solution used in the present invention is high, and to non-aqueous
Chemical stability, the physical stability of electrolyte are also high.Therefore, the porous layer containing the copolymer show it is wet when it is viscous
Connecing property is good, and the compatibility with electrolyte can be sufficiently kept when use at high temperature.
Vinylidene fluoride-hexafluoropropylene copolymer has the monomeric unit containing hydrophilic radical.As a result, be present in electrode surface
Active material, the adhesive ingredients in electrode interact, can be bonded securely.
As hydrophilic radical, hydroxyl, carboxyl, carboxylate, sulfonic group and their salt etc. can be enumerated.Especially preferably carboxylic
Base, carboxylate.
In order to import hydrophilic radical in vinylidene fluoride-hexafluoropropylene copolymer, such as the following methods can be given: in inclined fluorine
In the synthesis of ethylene-hexafluoropropylene copolymer, maleic anhydride, maleic acid, maleate, monomethyl maleate etc. are had hydrophilic
The monomer of group is by being copolymerized the method being directed into main chain；Pass through the side that grafting imports monomer in the form of side chain
Method.
The content lower limit value of the monomeric unit containing hydrophilic radical in vinylidene fluoride-hexafluoropropylene copolymer is preferably 0.1
Mole %, more preferably 0.3 mole of %, upper limit value is preferably 5 moles of %, more preferably 4 moles of %.By making containing hydrophilic radical
Monomeric unit content in above-mentioned preferred scope, the hydrophilic radical, with electrode in active material surface or electrode in
It interacts between the hydrophilic site hydrophilic radical of adhesive ingredients, cementability when enabling to have adequately wet.
If the monomeric unit containing hydrophilic radical content be 5 moles of % hereinafter, if can ensure sufficient polymer crystallinity, as a result,
Swellbility in electrolyte will can be inhibited in low-level, cementability when can obtain high wet.In addition, in porous layer
In containing in the case where particle, by making the content of the monomeric unit containing hydrophilic radical in above-mentioned preferred scope, can prevent
Particle falls off.The content of the monomeric unit containing hydrophilic radical in vinylidene fluoride-hexafluoropropylene copolymer can use FT-IR,
NMR, quantitative titration etc. are measured.For example, in the case where carboxyl, FT-IR can be used and on the basis of homopolymer, by C-
The absorption intensity ratio of H stretching vibration and the C=O stretching vibration of carboxyl is found out.
The content lower limit value of hexafluoropropene monomeric unit in vinylidene fluoride-hexafluoropropylene copolymer is preferably 0.3 to rub
You are %, and more preferably 0.5 mole of %, upper limit value is preferably 3 moles of %, more preferably 2.5 moles of %.If hexafluoropropene monomer list
The content of member is lower than 0.3 mole of %, then polymer crystallinity is high, reduces, is thus unable to get sufficiently to the swellbility of electrolyte
It is wet when cementability.In addition, can be excessively swollen to electrolyte if the content of hexafluoropropene is greater than 3 moles of %, cause to moisten
When cementability reduce.
Vinylidene fluoride-hexafluoropropylene copolymer can be obtained using known polymerization.It is following methods: ion is handed over
It changes water, monomethyl maleate, vinylidene and hexafluoropropene to be put into autoclave, suspension polymerisation is carried out, later by polymer syrup
Material dehydration, washing, are then dried, to obtain polymer powder.At this point, methyl fibre can be suitably used as suspending agent
Dimension element, as radical initiator, can be suitably used di-isopropyl peroxydicarbonate etc..
In the range of not damaging characteristic, vinylidene fluoride-hexafluoropropylene copolymer can be by further polymerizeing containing hydrophilic
Other monomers unit other than the monomeric unit of group and obtain.As other lists other than the monomeric unit containing hydrophilic radical
Body, such as the monomeric units such as tetrafluoroethene, trifluoro-ethylene, trichloro ethylene, ethylene fluoride can be enumerated.
The lower limit value of the weight average molecular weight of vinylidene fluoride-hexafluoropropylene copolymer is preferably 500,000, and more preferably 900,000, on
Limit value is preferably 2,000,000, and more preferably 1,500,000.By making the weight average molecular weight of vinylidene fluoride-hexafluoropropylene copolymer above-mentioned
In preferred scope, the time that copolymer is dissolved in solvent will not become extremely long, can be used in a manner of not reducing productivity.Separately
Outside, when being swollen in the electrolytic solution, it is able to maintain that appropriate gel strength.It should be noted that above-mentioned weight average molecular weight is to utilize
Gel permeation chromatography and the value to be converted with polystyrene.
[2] sodium carboxymethylcellulose
Sodium carboxymethylcellulose is the sodium salt of carboxymethyl cellulose ether, belongs to anionic cellulose ether.Contain carboxymethyl fibre
Cementability keeps effect good when the porous layer of the plain sodium of dimension can show wet.
Sodium carboxymethylcellulose can use known preparation method to obtain.Following methods etc. can be enumerated:
Absorbent cotton and sodium hydroxide alcohol are stirred into quaternization, cotton after alkalization with the mass ratio of 1:1 at 40 DEG C
Etherification reaction is stirred at 70 DEG C by a certain percentage with etherifying agent chloroacetic acid sodium, uses ethyl alcohol again with acetic acid neutralization after reaction
Obtain sodium carboxymethylcellulose after washing, cotton and etherifying agent are preferably in 1:0.6 to 1:0.9 when reaction, and correspondence degree of substitution is 0.6
To 0.9.
From the viewpoint of electrode cementability, the degree of substitution lower limit value of sodium carboxymethylcellulose is preferably 0.6, and upper limit value is excellent
It is selected as 0.9.By controlling degree of substitution, the swellbility to electrolyte is adjusted.Cementability can also be maintained when moistening as a result,.
For the total amount of vinylidene fluoride-hexafluoropropylene copolymer and sodium carboxymethylcellulose, carboxymethyl cellulose
The content lower limit value of sodium is preferably 0.5 mass %, and upper limit value is preferably 10 mass %, more preferably 3 mass %.Particularly, on
Limit value is further preferably lower than 8 mass %.By making it in above-mentioned preferred scope, bonding when can adequately be dried
Property and it is wet when cementability, and it is wet when cementability can effectively be kept in battery use process.By making carboxymethyl
The content of sodium cellulosate is 3 mass % or more, cementability when cementability and drying when more fully can realize wet simultaneously.It is logical
Crossing makes the 8 mass % of content of sodium carboxymethylcellulose hereinafter, being easy to get by vinylidene fluoride-hexafluoropropylene copolymer bring
The effect of cementability when wet.
[3] particle
The porous layer of battery separator of the invention can contain particle.It, can by containing particle in porous layer
The probability that short circuit occurs between positive electrode and negative electrode is reduced, it can be expected that the raising of safety.
As inorganic particulate, calcium carbonate, calcium phosphate, amorphism silica, crystallinity glass particle, kaolinite can be enumerated
Soil, talcum, titanium dioxide, aluminium oxide, silica-alumina composite oxide particle, barium sulfate, calcirm-fluoride, lithium fluoride, boiling
Stone, molybdenum sulfide, mica, boehmite etc..Particularly, from the crystalline growth of vinylidene fluoride-hexafluoropropylene copolymer, cost, obtain
Easy degree from the aspect of, preferably titanium dioxide, aluminium oxide, boehmite.
For the total amount of vinylidene fluoride-hexafluoropropylene copolymer, sodium carboxymethylcellulose and particle, porous layer
In the upper content limit value of particle that contains be preferably 85 mass %, more preferably 80 mass %, further preferably 75 mass %,
Lower limit value is preferably 30 mass %, more preferably 40 mass %, further preferably 50 mass %.By making the content of particle exist
In above-mentioned preferred scope, it is easy to get the good harmony of vapour lock degree.
From the viewpoint of inhibiting particle to fall off, the average grain diameter of particle is preferably the 1.5 of the average pore size of microporous membrane
Times or more and 50 times hereinafter, more preferably 2.0 times or more and 20 times or less.Mean flow pore size according to JISK3832,
ASTMF316-86 is measured, such as using Perm.Porometer (PMI corporation, CFP-1500A), according to dry type (Dry-
Up), the sequence of wet type (Wet-up) is measured.In wet type, to the PMI corporation Galwick (quotient known to surface tension
The name of an article) the micro-porous film that has been sufficiently impregnated applies pressure, the aperture that the conversion pressure penetrated through by air is obtained as
Maximum diameter of hole.For mean flow pore size, according to dry type measure in indicate pressure, flow curve 1/2 slope curve with
The pressure of the point of intersection of the curve of wet type measurement converses aperture.The conversion in pressure and aperture uses following mathematical expressions.
D=C γ/P
In above-mentioned formula, " d (μm) " is the aperture of micro-porous film, and " γ (mN/m) " is the surface tension of liquid, " P (Pa) "
For pressure, " C " is constant.
From battery (cell) wind when and core sliding property, particle fall off from the viewpoint of, the average grain diameter of particle is excellent
Be selected as 0.3 μm or more and 1.8 μm hereinafter, more preferably 0.5 μm or more and 1.5 μm hereinafter, further preferably 1.0 μm or more and
3.0 μm or less.The measurement device of laser diffraction mode or dynamic light scattering mode can be used to be measured for the average grain diameter of particle.
For example, passing through particle size distribution device (Nikkiso Company Limited's system, microtrac using ultrasonic probe
HRA) particle being scattered in the aqueous solution mixed with surfactant is measured, it preferably will be in terms of volume conversion from small particles
The value of the partial size (D50) when accumulating 50% is acted as average grain diameter in side.Shape of particle can enumerate ball shape, approximately spherical shape,
It is plate, needle-shaped, but be not particularly limited.
[4] physical property of porous layer
The thickness of every single face porous matter layer of microporous membrane be preferably 0.5 μm or more and 3 μm hereinafter, more preferably 1 μm with
It is lower and 2.5 μm or more, further preferably 1 μm or more and 2 μm or less.If every single side film thickness is 0.5 μm or more, can ensure
When wet cementability and it is dry when cementability.If every single side film thickness be 3 μm hereinafter, if be able to suppress winding volume, be suitable for from now on
The high capacity for the battery that can develop.
The porosity of porous layer is preferably 30% or more and 90% hereinafter, more preferably 40% or more and 70% or less.
It by making the porosity of porous layer in above-mentioned preferred scope, can prevent film resistance from rising, high current can be flowed through, and
It is able to maintain that film-strength.
[5] manufacturing method of battery separator
As shown in Figure 1, the manufacturing method of the battery separator of one embodiment of the present invention successively includes following preparation steps
(a)~(c).
Vinylidene fluoride-hexafluoropropylene copolymer is dissolved in solvent and obtains fluororesin solution by step (a)；
Step (b) adds carboxymethylcellulose sodium solution into fluororesin solution, carries out being mixed to get coating fluid；
Coating fluid is coated on microporous membrane, is impregnated in coagulating bath, then washed and dried by step (c).
(a) process of fluororesin solution is obtained
For solvent, as long as vinylidene fluoride-hexafluoropropylene copolymer can be dissolved, sodium carboxymethylcellulose is molten
Solution is dispersed and is mixed with solidification liquid, is not particularly limited.From the viewpoint of dissolubility, low volatility, solvent is preferred
For n-methyl-2-pyrrolidone.
In the case where the porous layer containing particle is arranged, it is important that the fluororesin that preparation is dispersed with particle in advance is molten
Liquid (also referred to as dispersion liquid).Vinylidene fluoride-hexafluoropropylene copolymer is dissolved in solvent, theretos while stirring and adds
Particle stirs certain time (for example, about 1 hour) with dispersion machine etc., thus carries out pre-dispersed.In turn, via using sand mill,
The process (dispersion step) that paint shaker disperses particle, thus, it is possible to obtain the few fluororesin solution of particles aggregate.
(b) process of coating fluid is obtained
This process is carboxymethylcellulose sodium solution to be added into fluororesin solution and using for example with agitating paddle
Three-one motor is mixed and the process for preparing coating fluid.
Carboxymethylcellulose sodium solution used in this process be sodium carboxymethylcellulose is dissolved or dispersed in solvent and
Obtained solution.The solvent used herein preferably identical solvent with step (a).It is examined from dissolubility, the viewpoint of low volatility
Consider, particularly preferred n-methyl-2-pyrrolidone.
In the case where the porous layer containing particle is arranged, it is important that after making particle be scattered in fluororesin solution
Addition (rear to be added) carboxymethylcellulose sodium solution.It is important that is, being added without sodium carboxymethylcellulose in dispersion step.When
When vinylidene fluoride-hexafluoropropylene copolymer, sodium carboxymethylcellulose and particle are added in solvent simultaneously, thus it is speculated that: because of inclined fluorine
Insoluble in the hydrophilic radical and sodium carboxymethylcellulose contained in ethylene-hexafluoropropylene copolymer, coating fluid start gradually
Thus gelation causes to be unsuitable for industrial application.Further, since the increased influence of viscosity, makes it difficult to carry out porous layer
Thickness becomes 3 μm of film coateds below.The step (a) in manufacturing method through the invention, (b), the gelation of coating fluid
It is suppressed, is able to carry out film coated, the storage stability of coating fluid also improves.
(c) coating fluid is coated on microporous membrane, be impregnated in coagulating bath, then the process washed and dried
This process is as follows: coating fluid being coated on microporous membrane, the microporous membrane after coating is impregnated in solidification liquid, is made
Vinylidene fluoride-hexafluoropropylene copolymer and sodium carboxymethylcellulose mutually separate, and have tridimensional network, coagulate in this state
Gu being washed and dried.Thus obtain having microporous membrane and positioned at microporous membrane surface porous layer battery with every
Film.
The method that coating fluid is coated on microporous membrane can be known method, such as can enumerate dip coating, reverse rollers
Rubbing method, gravure coating process, kiss coating, roller brush method, spray coating method, air knife coating method, Meyer stick rubbing method, pipe scraper for coating method,
Knife coating and die coating method etc., these methods can be used alone or in combination.
Solidification liquid is preferably water, preferably comprising 1 mass % or more and 20 mass % good solvents below (it is to inclined fluorine
Good solvent for ethylene-hexafluoropropylene copolymer and sodium carboxymethylcellulose) aqueous solution, more preferably include 5 mass %
Above and the aqueous solution of 15 mass % above-mentioned good solvent below.As good solvent, n-methyl-2-pyrrolidone, N can be enumerated,
Dinethylformamide, n,N-dimethylacetamide.Dip time in coagulating bath is preferably 8 seconds or more.The upper limit does not limit
System, when being 10 seconds, that is, abundant.
Water can be used in cleaning.Such as 100 DEG C of hot winds below can be used in drying.
Battery separator of the invention can be used as nickel-hydrogen cell, nickel-cadmium cell, nickel-zinc cell, silver-zinc battery, lithium from
The battery separator of the secondary cells such as sub- secondary cell, lighium polymer secondary battery, lithium-sulfur cell etc. uses.Particularly preferably make
It is used for the diaphragm of lithium ion secondary battery.
[6] physical property of battery separator
Battery separator it is wet when cementability can by it is wet when bending strength evaluated, bending strength is when wet
14N or more.The upper limit value of bending strength is not particularly limited when wet, when being 30N, that is, abundant.Bending strength when by making wet
In above-mentioned preferred scope, the part for being able to suppress the interface of diaphragm and electrode is free, is able to suppress battery internal resistance
Increase, inhibit the reduction of battery behavior.
When the drying of battery separator cementability can by it is dry when bending strength evaluated, bending strength when dry
Lower limit value is preferably 7N or more, more preferably 9N or more.The upper limit value of bending strength is not particularly limited when dry, when being 30N
I.e. sufficiently.Bending strength is easy to inhibit the flexure of rolled electrode bodies, deformation in above-mentioned preferred scope when by making dry.
From it is dry when cementability and it is wet when cementability harmony from the viewpoint of, preferred battery diaphragm it is wet when
Bending strength is 7N or more when bending strength is 14N or more and dries.
Embodiment described below is specifically described, but the present invention is not by any restrictions of these embodiments.It needs
Bright, the measured value in embodiment is the value measured using following methods.
1. bending strength when wet
Typically, has the Porous comprising fluororesin using the adhesive of fluororesin in anode and on diaphragm
In the case where layer, by the mutual phase counterdiffusion of fluororesin, it is easy to ensure that cementability.On the other hand, fluorine removal tree is used in cathode
Adhesive other than rouge, it is difficult to the diffusion of fluororesin occur, therefore compared with anode, cathode is difficult to obtain bonding with diaphragm
Property.Therefore, in this measurement, bending strength as described below is evaluated into the cementability between diaphragm and cathode as index.
(1) production of cathode
Aqueous solution comprising 1.5 mass parts carboxymethyl celluloses is added into the artificial graphite of 96.5 mass parts, is carried out
Mixing, and then the styrene butadiene latices of 2 mass parts as solid state component are added, it is mixed, is made containing cathode agent
Slurry.The slurry containing cathode agent is uniformly coated on two of the negative electrode collector formed by copper foil with a thickness of 8 μm
It on face, is dried to form negative electrode layer, compression forming is carried out by roll squeezer later, makes the density of the negative electrode layer in addition to collector
For 1.5g/cm3, cathode is thus made.
(2) the test production of coiling body
To manufactured cathode (mechanical direction 161mm × width direction 30mm) and Examples and Comparative Examples in the above described manner
In the overlapping of manufactured diaphragm (mechanical direction 160mm × width direction 34mm), by metal plate, (length 300mm, width are
25mm, with a thickness of 1mm) it is used as core, diaphragm and cathode are wound in such a way that diaphragm becomes inside, metal plate is extracted out, is tried
It tests and uses coiling body.Test is length about 34mm × width about 28mm with coiling body.
(3) measuring method of bending strength when moistening
It is placed on the laminated film (length 110mm, width 65mm, with a thickness of 0.12mm) formed by aluminium and polypropylene
Test coiling body, is made the bag-shaped of openings at one side for the both sides welding of laminated film for laminated film doubling along its length.?
In the solvent that ethylene carbonate and methyl ethyl carbonate are obtained by mixing with volume ratio 3: 7, dissolved with the ratio of 1mol/L
LiPF6 is to obtain electrolyte, in glove box, injects 500 μ L electrolyte to be impregnated with test coiling body, later from opening portion
With vacuum closing apparatus by the sealing on one side of opening portion.
Then, the test coiling body into laminated film is enclosed with 2 gaskets (thickness 1mm, 5cm × 5cm) clamping, used
Precision heating pressurizing device (Xindong Industry Co's system, CYPT-10) is pressurizeed 2 minutes under conditions of 98 DEG C, 0.6MPa, in
It is placed at room temperature for cooling.For enclosing to the test coiling body of laminated film after pressurization, universal testing machine (Co., Ltd. island is used
Saliva makes made, AGS-J) bending strength when measuring wet as the schematic diagram of Fig. 1.It records in detailed below.
For 2 aluminum L shape angle sections (angle) 4 (thickness 1mm, 10mm × 10mm, length 5cm), upward with 90 ° of parts
Mode end pendulum is configured together in parallel, using 90 ° of parts as fulcrum and by distance between the fulcrum as in a manner of 15mm
It is fixed.Test is set to use the midpoint on the side (about 28mm) of the width direction of coiling body and the branch as 2 aluminum L shape angle sections
It is overlapped at the 7.5mm of the centre of distance between point, test volume is configured in a manner of not exposing from the side of the length direction of L shape angle section
Around body.
Then, use the side (about 34mm) of the length direction of coiling body not from the aluminum L shape angle section 3 as pressure head using test
It mode that the side of the length direction of (with a thickness of 1mm, 10mm × 10mm, length 4cm) is exposed and is set in parallel, makes aluminum
90 ° of parts of L shape angle section 3 are overlapped with the midpoint on the side of the width direction of test coiling body, in such a way that 90 ° of parts are directed downwardly,
Aluminum L shape angle section 3 is fixed on to the load cell of universal testing machine (capacity of load cell is 50N).For in 0.5mm/min
Load speed under measured value at 0.5mm stroke (stroke) of test load when becoming 0.05N, by 3 tests with winding
The average value of body is as bending strength when moistening.
2. bending strength when dry
(1) production of cathode
Using with above-mentioned 1. it is wet when the same cathode of bending strength.
(2) the test production of coiling body
Using with above-mentioned 1. it is wet when the same test coiling body of bending strength.
(3) measuring method of bending strength when dry
The test coiling body being ready for is clamped using 2 gaskets (thickness 1mm, 5cm × 5cm), is added using precision heating
Pressure device (Xindong Industry Co's system, CYPT-10) pressurizes 2 minutes under conditions of 90 DEG C, 0.6MPa, cold in being placed at room temperature for
But.For the test coiling body after pressurization, as shown in Fig. 2, in the same manner as the measuring method of bending strength when above-mentioned 1. is wet
Configuration, using universal testing machine (Shimadzu Scisakusho Ltd's system, AGS-J) and by the following conditions to 3 test coiling bodies
It is measured, using the average value of maximum test force as bending strength when drying.
Distance between the fulcrum: 15mm
Maximum range: 50N
Load speed: 0.5mm/min
3. powder falling is evaluated
In such a way that porous layer becomes surface, by diaphragm corrugationless, it is flatly fixed to plummet with handles (1143g)
Bottom surface (floor space be 5.5cm × 6cm).Keep plummet past on drawing paper (Daio Seishi KK's system, C-55, black)
10 20cm distance movements are carried out again, and the amount for being then transferred to drawing paper to porous layer confirms.At any selection 10
The range of 5mm × 5mm measures the number of 150 μm or more of film cast using optical microscopy, and powder falling is with de-
The number meter of junk is evaluated as follows.
Good: film cast at 10 adds up to 50 or less.
Bad: film cast at 10 adds up to 51 or more.
4. film thickness
Using contact film thickness gauge (M Co., Ltd. itsutoyo system " Litematic " (registered trademark) series318),
Using superhard spherical surface measure son, load be 0.01N under conditions of measure 20 points, using the average value of obtained measured value as
Film thickness.
5. bonding force holding capacity (expansion rate) when wet
Using film thickness gauge under film thickness test condition distinguish test loop before cell thickness R1 and circulation 1000 weeks after thickness
R2 calculates bonding force holding capacity, that is, expansion rate when expansion rate represents wet: expansion rate=(R2-R1)/R1 by lower section formula.
Embodiment
Embodiment 1
[biasfluoroethylene-hexafluoropropylene (VdF-HFP) copolymer]
Using vinylidene, hexafluoropropene and monomethyl maleate as starting material, inclined fluorine is synthesized using suspension polymerization
Ethylene-hexafluoropropylene copolymer (a).It is measured by NMR, the weight of the vinylidene fluoride-hexafluoropropylene copolymer confirmed is equal
Molecular weight is 1,500,000, vinylidene fluoride monomers unit/hexafluoropropene monomeric unit/monomethyl maleate monomeric unit molar ratio
For 98.5/1.0/0.5.
[sodium carboxymethylcellulose]
Absorbent cotton and sodium hydroxide alcohol are stirred into quaternization, cotton after alkalization with the mass ratio of 1:1 at 40 DEG C
Etherification reaction is stirred at 70 DEG C by a certain percentage with etherifying agent chloroacetic acid sodium, uses ethyl alcohol again with acetic acid neutralization after reaction
Sodium carboxymethylcellulose is obtained after washing, cotton and etherifying agent are 1:0.8, and acquired sodium carboxymethylcellulose degree of substitution is 0.8.
[production of battery separator]
28.5 mass parts vinylidene fluoride-hexafluoropropylene copolymers (a) and 641 mass parts NMP are mixed, uses divide on one side later
Dissipate machine stirring, 70 mass parts aluminium oxide particles (1.1 μm of average grain diameter) be added on one side as inorganic particulate, with dispersion machine with
2000rpm is stirred 1 hour in advance.Then, using Dyno-Mill (SHINMARU ENTERPRISES CORPORATION Dyno-
Mill MultiLab (1.46L container, filling rate 80%, alumina bead)), in the peripheral speed condition of the flow of 11kg/h, 10m/s
Lower processing 3 times, obtains dispersion liquid.Carboxymethylcellulose sodium solution is mixed in dispersion liquid, uses the Three- for having agitating paddle
For One Motor with 500rpm stirring 30 minutes, it was 13 mass %, aluminium oxide particles that solid component concentration, which is obtained by filtration:
Copolymer (a): the coating fluid that the mass ratio of sodium carboxymethylcellulose is 70: 28.5: 1.5.Using dip coating in thickness
The two sides applied coating solution for the microporous polyethylene film that degree is 7 μm, then it is allowed to dipping in aqueous solution, it is cleaned with pure water,
Then in 50 DEG C of dryings, 11 μm of thickness of battery separator is obtained.
Embodiment 2
Use becomes 13 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a) with solid component concentration:
The mass ratio of sodium carboxymethylcellulose as 70: 29.2: 0.8 the coating fluid that is prepared of mode, in addition to this with embodiment 1
It operates in the same way, obtains battery separator.For obtained battery separator, powder falling evaluation is carried out, result is good.
Embodiment 3
Use becomes 13 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a) with solid component concentration:
The mass ratio of sodium carboxymethylcellulose as 70: 28.2: 1.8 the coating fluid that is prepared of mode, in addition to this with embodiment 1
It operates in the same way, obtains battery separator.
Embodiment 4
Use becomes 13 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a) with solid component concentration:
The mass ratio of sodium carboxymethylcellulose as 70: 27.5: 2.5 the coating fluid that is prepared of mode, in addition to this with embodiment 1
It operates in the same way, obtains battery separator.
Embodiment 5
Use becomes 12 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a) with solid component concentration:
The mass ratio of sodium carboxymethylcellulose as 65: 33.7: 1.3 the coating fluid that is prepared of mode, in addition to this with embodiment 1
It operates in the same way, obtains battery separator.
Embodiment 6
Use becomes 18 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a) with solid component concentration:
The mass ratio of sodium carboxymethylcellulose as 85: 13.4: 0.6 the coating fluid that is prepared of mode, in addition to this with embodiment 1
It operates in the same way, obtains battery separator.
Embodiment 7
Use boehmite (average grain diameter be 2.3 μm) as inorganic particulate and the coating fluid for preparing, in addition to this with implementation
Example 2 operates in the same way, and obtains battery separator.
Embodiment 8
Use titanium dioxide (average grain diameter be 1 μm) as inorganic particulate and the coating fluid for preparing, in addition to this with implementation
Example 2 operates in the same way, and obtains battery separator.
Embodiment 9
Make battery separator with a thickness of 10 μm, operate similarly to Example 2 in addition to this, obtain battery separator.
Comparative example 1
Use becomes 13 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a) with solid component concentration
Mass ratio as 70: 30 coating fluid that is prepared of mode, operate similarly with example 1 in addition to this, obtain battery
Use diaphragm.For obtained battery separator, powder falling evaluation is carried out, result is bad.
Comparative example 2
Inclined fluorine is replaced using PVdF homopolymer (Co., Ltd.'s Kureha system, KF#7300 (molecular weight is by 1,000,000 or more))
Ethylene-hexafluoropropylene copolymer prepares coating fluid, and the coating fluid obtained using this is operated similarly to Example 2 in addition to this,
Obtain battery separator.
Comparative example 3
Vinylidene fluoride-hexafluoropropylene copolymer (the b) (Arkema that content using hexafluoropropene monomer is 4.5 moles of %
50 ten thousand) Co. Ltd. system, kynar2801 (molar ratio of VdF/HFP is 95.5/4.5, and molecular weight is lower than) replace inclined fluorine second
Alkene-hexafluoropropylene copolymer (a) prepares coating fluid, and the coating fluid obtained using this is grasped similarly to Example 2 in addition to this
Make, obtains battery separator.
Comparative example 4
Using solid component concentration be 5 mass % CRV (Shin-Etsu Chemial Co., Ltd's system, cyano ethyl PVA) and
The solution of n-methyl-2-pyrrolidone replaces the carboxymethylcellulose sodium solution of embodiment 2 to prepare coating fluid, is obtained using this
Coating fluid, operate similarly to Example 2 in addition to this, obtain battery separator.
Comparative example 5
Become 25 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a): carboxylic first with solid component concentration
The mass ratio of base sodium cellulosate prepares coating fluid as 90: 9.1: 0.9 mode, operates similarly to Example 2 in addition to this,
Obtain battery separator.
Comparative example 6
Become 13 mass %, aluminium oxide particles: vinylidene fluoride-hexafluoropropylene copolymer (a): carboxylic first with solid component concentration
The mass ratio of base sodium cellulosate becomes 70: 27.2: 2.8 mode, while mixed inorganic particle, biasfluoroethylene-hexafluoropropylene are total
Polymers (a), sodium carboxymethylcellulose, n-methyl-2-pyrrolidone carry out dispersion and prepare coating fluid, but the viscosity of coating fluid increases
Add, microporous polyethylene film can not be coated on.
Comparative example 7
Make battery separator with a thickness of 9 μm, operate similarly to Example 2 in addition to this, obtain battery separator.
Comparative example 8
In such a way that the solid component concentration of vinylidene fluoride-hexafluoropropylene copolymer becomes 5 mass %, N- methyl-is used
2-Pyrrolidone prepares coating fluid, the coating fluid obtained using this, and make battery separator with a thickness of 9.5 μm, in addition to this
It operates similarly with example 1, obtains battery separator.
The characteristic of battery separator obtained in Examples 1 to 9, comparative example 1~8 is shown in table 1.
The content (quality %) of sodium carboxymethylcellulose indicates that sodium carboxymethylcellulose is fine relative to fluororesin and carboxymethyl
Tie up the quality % of the gross mass of plain sodium." rear to be added " in coating material preparation indicates in the fluororesin solution for being dispersed with particle
Carboxymethylcellulose sodium solution is added." being added simultaneously " indicates while fluororesin solution, carboxymethylcellulose sodium solution, grain is added
Son carries out decentralized processing.
Table 1
In conclusion the diaphragm has microporous membrane and sets the present invention provides a kind of diaphragm for non-water system secondary battery
It is placed in the porous layer of at least one side of the microporous membrane.Porous layer includes vinylidene fluoride-hexafluoropropylene copolymer and carboxylic first
Base sodium cellulosate, when vinylidene fluoride-hexafluoropropylene copolymer provides dry cementability and it is wet when cementability, carboxymethyl cellulose
Sodium effectively can inhibit porous layer to be excessively swollen, and cementability will not occur apparent with the recycling of battery when guaranteeing wet
Deteriorate, to guarantee the excellent performance of battery.
The above-described embodiments merely illustrate the principles and effects of the present invention, and is not intended to limit the present invention.It is any ripe
The personage for knowing this technology all without departing from the spirit and scope of the present invention, carries out modifications and changes to above-described embodiment.Cause
This, institute is complete without departing from the spirit and technical ideas disclosed in the present invention by those of ordinary skill in the art such as
At all equivalent modifications or change, should be covered by the claims of the present invention.
Claims (16)
1. a kind of diaphragm for non-water system secondary battery, which is characterized in that the diaphragm includes at least microporous membrane and is set to institute
State the porous layer of a microporous membrane at least side surface；
Wherein, the porous layer includes vinylidene fluoride-hexafluoropropylene copolymer and sodium carboxymethylcellulose, the inclined fluorine second
Alkene-hexafluoropropylene copolymer has monomeric unit and hexafluoropropene monomeric unit containing hydrophilic radical.
2. diaphragm for non-water system secondary battery according to claim 1, it is characterised in that: the monomer containing hydrophilic radical
Unit is in the molar content in the vinylidene fluoride-hexafluoropropylene copolymer between 0.1 mole of % to 5 moles of %.
3. diaphragm for non-water system secondary battery according to claim 1, it is characterised in that: the monomer containing hydrophilic radical
Unit includes maleic anhydride monomer units, maleic acid monomer units, maleate monomer unit, monomethyl maleate monomeric unit
One of or it is a variety of.
4. diaphragm for non-water system secondary battery according to claim 1, it is characterised in that: the hexafluoropropene monomeric unit
In the molar content in the vinylidene fluoride-hexafluoropropylene copolymer between 0.3 mole of % to 3 moles of %.
5. diaphragm for non-water system secondary battery according to claim 1, it is characterised in that: the vinylidene-hexafluoro third
The matter average molecular weight of alkene copolymer is between 500,000~2,000,000.
6. diaphragm for non-water system secondary battery according to claim 1, it is characterised in that: press the vinylidene-hexafluoro
The gross mass meter of propylene copolymer and the sodium carboxymethylcellulose, the content of the sodium carboxymethylcellulose is between 0.5 matter
% is measured between 10 mass %.
7. diaphragm for non-water system secondary battery according to claim 1, it is characterised in that: the porous layer also includes
Particle.
8. diaphragm for non-water system secondary battery according to claim 7, it is characterised in that: press the vinylidene-hexafluoro
The gross mass meter of propylene copolymer, the sodium carboxymethylcellulose and the particle, the content of the particle is between 20 mass %
To between 85 mass %.
9. diaphragm for non-water system secondary battery according to claim 7, it is characterised in that: the particle include aluminium oxide,
One of titanium dioxide and boehmite are a variety of.
10. diaphragm for non-water system secondary battery according to claim 7, it is characterised in that: the average grain diameter of the particle is situated between
Between 0.3 μm~3.0 μm.
11. according to right want 1 described in diaphragm for non-water system secondary battery, it is characterised in that: the porous layer of every single side
Thickness between 0.5 μm~4 μm.
12. according to right want 1 described in diaphragm for non-water system secondary battery, it is characterised in that: the diaphragm it is wet when be bent
Intensity in 14N or more, the drying of the diaphragm bending strength in 7N or more.
13. according to right want 1 described in diaphragm for non-water system secondary battery, it is characterised in that: the microporous membrane includes polyene
Hydrocarbon microporous membrane.
14. a kind of preparation method of diaphragm for non-water system secondary battery, which is characterized in that the preparation method includes at least:
(a) vinylidene fluoride-hexafluoropropylene copolymer is dissolved in solvent, obtains fluororesin solution；
(b) carboxymethylcellulose sodium solution is added in the fluororesin solution, is mixed to get coating fluid；
(c) microporous membrane is provided, the coating fluid is coated on to an at least side surface for the microporous membrane, then be impregnated in solidification
It in bath, cleaned, dried later, obtain the diaphragm.
15. according to right want 14 described in diaphragm for non-water system secondary battery preparation method, it is characterised in that: the inclined fluorine second
Alkene-hexafluoropropylene copolymer preparation method includes: by ion exchange water, the monomer containing hydrophilic radical, vinylidene and hexafluoro
Propylene is put into autoclave, carries out suspension polymerisation, is obtained polymer paste, is later dehydrated the polymer paste, water
It washes and dries, to obtain vinylidene fluoride-hexafluoropropylene copolymer.
16. according to right want 14 described in diaphragm for non-water system secondary battery preparation method, it is characterised in that: in step (a),
Vinylidene fluoride-hexafluoropropylene copolymer is dissolved in solvent and is stirred, particle is added in stirring while, obtains being dispersed with particle
Fluororesin solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811203510.3A CN109546059A (en) | 2018-10-16 | 2018-10-16 | A kind of diaphragm for non-water system secondary battery and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811203510.3A CN109546059A (en) | 2018-10-16 | 2018-10-16 | A kind of diaphragm for non-water system secondary battery and preparation method thereof |
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| CN113597683A (en) * | 2020-09-30 | 2021-11-02 | 宁德新能源科技有限公司 | Electrode assembly, battery and preparation method of electrode assembly |
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| CN113597683A (en) * | 2020-09-30 | 2021-11-02 | 宁德新能源科技有限公司 | Electrode assembly, battery and preparation method of electrode assembly |
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