CN102464803A - Porous membrane and preparation method thereof - Google Patents

Porous membrane and preparation method thereof Download PDF

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Publication number
CN102464803A
CN102464803A CN2010105515947A CN201010551594A CN102464803A CN 102464803 A CN102464803 A CN 102464803A CN 2010105515947 A CN2010105515947 A CN 2010105515947A CN 201010551594 A CN201010551594 A CN 201010551594A CN 102464803 A CN102464803 A CN 102464803A
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film
porous
solvent
pvdf
preparing porous
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李翔
孙庆津
唐杰
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Microvast Power Systems Huzhou Co Ltd
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Microvast Power Systems Huzhou Co Ltd
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Priority to CN2010105515947A priority Critical patent/CN102464803A/en
Priority to PCT/CN2010/002200 priority patent/WO2012061963A1/en
Publication of CN102464803A publication Critical patent/CN102464803A/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002Organic membrane manufacture
    • B01D67/0009Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403Manufacturing processes of separators, membranes or diaphragms
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/414Synthetic resins, e.g. thermoplastics or thermosetting resins
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/414Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426Fluorocarbon polymers
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491Porosity
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

The invention provides a preparation method of a porous membrane, comprising the following steps: mixing and dispersing a polymer and solvent to prepare slurry; enabling the slurry to flow out of a narrow break joint to form a membrane in a gel tank; introducing the membrane to an extraction tank to carry out solvent replacement to form the porous membrane; and drying the porous membrane. The preparation method is simple in process, precise in control, low in cost and high process safety. The porous membrane prepared by using the preparation method can be widely applied to primary batteries, secondary batteries, electrochemical containers and the like.

Description

Porous-film and preparation method thereof
Technical field
The present invention relates to a kind of porous-film and method of manufacture thereof.
Background technology
Porous-film is often referred to the film that has certain porosity on the unit surface.
Porous-film adopts non-solvent induction phase conversion method (DIPS) or thermally induced phase separation (TIPS) preparation more.The development of non-solvent induction phase conversion method is morning, technological comparative maturity, and method is also relatively simple, but the film bad mechanical strength that makes, porosity is low.Thermally induced phase separation is to utilize crystallinity and thermoplastic polymer and high boiling point, low-molecular-weight thinner when high temperature, to form the homogeneous phase film-casting liquid, and solid-liquid or liquid-liquid phase separation take place when temperature reduces, and removes thinner afterwards, obtains polymer microporous film.TIPS method more complicated, often needing polymkeric substance and thinner is multicomponent mixture, high temperature and a large amount of extraction solvents, production cost is high.
With the polyolefin resin is that main porous-film can be used for fields such as battery diaphragm, capacitor diaphragm.As one of method of manufacture of this porous-film, generally be to extrude with containing high-molecular weight polyolefin resin heating and melting, stretching makes porous-film.
Barrier film is one of key components of battery, between the positive and negative electrode of battery, is used for isolating positive and negative electrode, avoids internal short-circuit of battery, guarantees that again ion can pass through smoothly simultaneously when discharging and recharging.The barrier film that is used for battery is a kind of electronic insulating film of vesicular structure, has high ionic conduction performance and excellent mechanical intensity, can chemical reaction not take place at the medium-term and long-term stable existence of electrolytic solution.In secondary cell, the quality of membrane properties directly affects the key property of the batteries such as internal resistance, capacity, charging and discharging currents density, cycle life and safety of battery.To lithium-ion secondary cell, membranous cost has occupied the 15-30% of lithium ion battery (especially for the lithium ion power secondary cell of electric vehicle) cost.Therefore, barrier film all plays important effect to the performance and the cost of lithium-ion secondary cell.
The barrier film that just is being widely used in the lithium-ion secondary cell at present is a polyolefins melting tensile membrane; Be mainly Vestolen PP 7052, Vilaterm single-layer septum, or three layers of composite diaphragm of polypropylene, polyethylene/Vestolen PP 7052; Its vesicular structure is generally the stretching communicating pores, and the aperture is greatly between 0.01-1 μ m.And because the restriction of itself polyolefins material; Its environment for use temperature should not be too high; In the Working environment of high current charge-discharge, internal temperature of battery possibly raise rapidly, makes the polyolefins diaphragm closed pore easily even thermal contraction takes place; And then the internal resistance of cell is significantly increased, finally cause battery failure.Therefore, existing polyolefins barrier film is difficult to satisfy lithium ion power secondary cell that big electric current high magnification charges and discharge to membranous requirement.
In order to improve the thermostable type of membranous working temperature and lithium-ion secondary cell; It is body material with PET (polyethylene terephthalate) non-woven fabrics that goldschmidt chemical corporation (Degussa) has been developed a kind of, has the barrier film (USP and trademark office's application number 20080245735) of nano ceramics Dipping.This barrier film fusing point is more than 220 ℃, and Heat stability is good can improve the high rate during charging-discharging of lithium ion battery.But; Nano ceramic coat in this barrier film and non-woven fabrics matrix material are because sticking power is relatively poor; In the course of processing of battery, cause barrier film folding line and breakage easily, even the ceramic coating serial problems such as causing defective that comes off, thereby the potential safety hazard in the battery use caused.
In order to solve the non-woven fabrics porous matrix--in the inorganic nano stupalith composite diaphragm, the problem that inorganic coating comes off easily, invention has before proposed on the HMP porous matrix material, to be coated with organic polymer film forming materials such as polyolefins hybrid resin.Related patent U.S. Patent No. is like CN101635341, CN101471432A, CN1670989A etc.This has strengthened the sticking power of porous matrix material and top coat under the prerequisite that guarantees the barrier film thermostability, improved membranous crooked coiling ability.But, in the process of porous matrix material surface coated macromolecule filming material, cause the obstruction in body material hole easily, and there are problems such as thermal-shrinkage differential in different macromolecular material, and then influence the correlated performance of barrier film and battery.
The Asahi-Kasei of Japan and related patent U.S. Patent No. JP2004323820, the US6245272 of Tonen Chemical company disclose a kind of thermic phase disengagement method (TIPS).This method is at high temperature polymkeric substance to be dissolved in high boiling point, the low voc solvent (thinner); Extrude the formation sheet then; Cooling is separated the solution generation on chill roll, adopts two-way stretch equipment that it is carried out vertically and horizontally stretching, obtains to have the film of phase separation structure; Use volatile organic solvent thinner to be extracted, form macromolecule membrane with certain microvoid structure as extraction agent.
Preparing method's (U.S. Pat 5460904) that U.S. Bell Communications Research company announced a kind of membrane for polymer in 1994; The PVDF-HFP multipolymer is dissolved in acetone or N-Methyl pyrrolidone or their mixing solutions; Add a certain amount of softening agent; Can also add gaseous oxidation silicon or aluminum oxide etc. again, process slurry, process certain thickness film with coating machine; Obtain wet film after the solvent evaporated, re-use extraction agent softening agent is extracted after drying makes dry film.The maximum drawback of this method is to need to use a large amount of extraction agents, has increased preparation technology's complexity and cost.
The Tonen Chemical company of Japan discloses a kind of preparation method of micropore polyolefin film in patent US20090286161A1, comprise that (1) is with polyolefin resin and film forming solvent melting mixing; (2) with the solution extrusion molding; (3) cooling extruded thing forms gel film; (4) it is stretched; (5) remove film forming solvent and form microporous membrane; (6) redrawing; The microporous membrane thermoforming that (7) will stretch makes the micropore polyolefin film.This method need pass through cooling gel, remove solvent and twice drawing process, the technology relative complex, and cost is higher, is unfavorable for scale operation.
Summary of the invention
In order to solve the deficiency of said product and preparation method thereof, the present invention provides a kind of preparation method of new porous-film and by the porous-film of this method preparation.
An object of the present invention is to provide a kind of preparation method of porous-film, may further comprise the steps:
A) polymkeric substance and solvent are carried out blending dispersion, make slurry;
B) slurry in a) is flowed out through the narrow shape break joint in the gel groove, form film;
C) with b) in film introduce in the extraction tank and carry out solvent exchange, form porous membrane;
D) porous membrane is carried out drying.
Polymkeric substance is that be selected from can be by the polymkeric substance of the dissolution with solvents of using simultaneously, comprising in fluoropolymer, Rohm tech inc (PMMA), polyacrylonitrile (PAN), polyoxyethylene (PEO), polysulfones (PS), polyethersulfone (PES) and the SE (PVC) one or more.
Fluoropolymer is selected from pvdf (PVDF) and contains in the multipolymer of pvdf one or both.Wherein, the multipolymer that contains pvdf is selected from one or both in pvdf-R 1216 (PVDF-HFP) and pvdf-trifluorochloroethylene (PVDF-CTFE) multipolymer.
It is the organic solvent more than 150 ℃ that solvent is selected from boiling point.Organic solvent can be N-Methyl pyrrolidone (NMP), DMAC N,N (DMAC), N, one or more in dinethylformamide (DMF), methyl-sulphoxide (DMSO) and the triethyl phosphate (TEP).Preferably, organic solvent is N-Methyl pyrrolidone (NMP).
Above-mentioned in step a), the quality proportioning of solvent and polymkeric substance becomes performances such as film toughness and pore structure to have very important influence to final.In addition, the quality proportioning of solvent and polymkeric substance has also determined the viscosity of slurry, and then influences follow-up operation steps and film-forming process.According to the embodiment of the present invention, the mass ratio of solvent and polymkeric substance is 1~4, is preferably 1.5~3.In dispersion process, can also continue to add solvent to regulate the high molecular polymer slurry viscosity and to become pore structure.
The material of preparation slurry can also comprise inorganic salt in the step a).In part embodiment of the present invention, through adding inorganic salt, can improve the formation of finger-like pore in film process to a certain extent, make pore-forming more even distribution and regular.Employed inorganic salt are for can be dissolved in the inorganic salt that boiling point is an organic solvent more than 150 ℃.In an embodiment of the present invention, preferred inorganic salt are lithium chloride (LiCl).The quality proportioning of inorganic salt and solvent is that mass ratio is 0.005~0.1, is preferably 0.01~0.05.
In the step a), polymkeric substance and solvent and inorganic salt are carried out thorough mixing,, need dispersion temperature be controlled in certain scope in order to reach the better mixing dispersion effect.According to the concrete polymkeric substance and the different in kind of solvent, the TR of blending dispersion process is 50-150 ℃, is preferably 60-100 ℃.
Step a) comprises carries out blending dispersion with polymkeric substance and solvent and inorganic salt through multiple screw extruder, forms slurry.Blending dispersion also can adopt mixing and dispersing device commonly used in any industry, because the higher institute of polymer content of the present invention causes slurry viscosity higher, therefore adopts the multiscrew machine, carries out blending dispersion such as dual-screw-stem machine, three screw rod machines.Simultaneously, can be with the Melt Pump use of connecting with multiple screw extruder.Through method and accurate material proportion and the temperature control mentioned in a) in above-mentioned steps, the present invention has realized the slurry film-forming process of higher polymer content.
Above-mentioned steps b) in, comprises slurry is flowed out with mouth mould mode through the narrow shape break joint.Then fluid is introduced and be equipped with in the gel groove of coagulant liquid, also realize being separated of polymkeric substance and solvent simultaneously, form porous membrane through coagulant liquid gel film forming.Coagulant liquid is selected from any liquid that can make the polymeric film gel.According to the embodiment of the present invention, coagulant liquid is a water.The temperature of coagulant liquid can be controlled its temperature at 20-95 ℃ according to the size in required film forming caudacoria surface micro aperture.
Above-mentioned steps c) in, film gets into repeatedly washing in the extraction tank that extraction liquid is housed through take off roll.According to the embodiment of the present invention, extraction liquid is a water.
Above-mentioned steps b) and c), coagulant liquid and extraction liquid are water, and this is one of characteristics of the present invention.On the one hand, owing to make water, preparation cost is low; On the other hand, the feature of environmental protection in the production process and security are greatly improved.
Above-mentioned steps d) in, gets into drying oven through take off roll,, make porous-film of the present invention through after the thorough drying through the wet thin of extraction.
At step b), c) or d) in, can stretch to said film or porous diaphragm.It is between 1.03 to 1.30 that stretch ratio is controlled at.
According to the embodiment of the present invention, further comprise step b) and c) in the step that reclaims of the solvent of coagulant liquid, extraction liquid.The separating technology of mixing liquid can adopt the conventional solvent separation method to carry out like technologies such as distillations.If contain the embodiment of inorganic salt, also comprise the step that reclaims inorganic salt.
Another object of the present invention provides a kind of porous-film, comprises the film with vesicular structure by polymer formation, and said vesicular structure is the three dimensional network pore structure that connects each other.
Polymkeric substance is that be selected from can be by the polymkeric substance of the dissolution with solvents of using simultaneously, comprising in fluoropolymer, Rohm tech inc (PMMA), polyacrylonitrile (PAN), polyoxyethylene (PEO), polysulfones (PS), polyethersulfone (PES) and the SE (PVC) one or more.
Fluoropolymer is selected from pvdf (PVDF) and contains in the multipolymer of pvdf one or both.Wherein, the multipolymer that contains pvdf is selected from one or both in pvdf-R 1216 (PVDF-HFP) and pvdf-trifluorochloroethylene (PVDF-CTFE) multipolymer.
The thickness of said porous-film is 10-400 μ m, preferred 20-100 μ m.
The porosity of said porous-film is 30-80%, preferred 50-70%.
The aperture of said porous-film is 0.01-5 μ m, preferred 0.01-2 μ m.
Porous-film provided by the invention can be widely used in industry and civilian purposes such as primary cell (like alkaline cell), secondary cell (comprising lithium ion battery, polymer Li-ion battery, electrochemical capacitor, nickel metal hydride battery etc.).
Method for preparing porous film provided by the invention all has strict restriction to solvent and inorganic salt usage quantity, kind and performance, and the boiling point of solvent is higher, and requires inorganic salt can be dissolved in the employed solvent, and slurry disperses process temperature control accurately.And in the film process of porous membrane, can only use a kind of organic solvent and a kind of inorganic salt, need not use any second kind of organic solvent, softening agent or other auxiliary agents, not introduce other organic solvents and component.This method can realize the slurry film-forming process of higher polymer solids level, thereby the usage quantity that makes solvent is than the obvious minimizing of other technologies.Water has been simplified follow-up organic solvent and mixed solution process for separating and recovering as unique coagulant liquid and extraction liquid, makes solvent and inorganic salt obtain efficient recovery and utilizes, has reduced the pollution of trade waste to environment.The whole process of preparation step is simple, cost is low, safe.
Porous-film provided by the invention; Be used for lithium ion secondary battery membrane in an embodiment; Make that the performance of battery is improved significantly, include but not limited to effectively reduce battery internal resistance, improve battery and in groups the back power brick safety performance and big electric current high-rate charge-discharge capability, very significantly prolonged the cycle life of battery.
Usually, the barrier film through traditional drawing process preparation forms the clear opening structure easily.Under the identical situation of other conditions, the barrier film that generally has clear opening has bigger air penetrability than having the three dimensional network pore structure barrier film that communicates with each other.Method for preparing porous film provided by the invention, prepared barrier film but has higher air penetrability.According to the embodiment of the present invention, membranous air penetrability is 20-500S/100CC, preferred 30-300S/100CC.
On the other hand, the lithium ion secondary battery membrane that uses as power cell needs big porosity to help improving the electrolytic solution liquid absorption, for the conduction of lithium ion more hyperchannel and path is provided simultaneously.Porous-film provided by the invention can also significantly improve membranous porosity, and has good electrolytic solution imbibition wettability, makes battery have lower internal resistance and higher ionic conductivity.
Description of drawings
Fig. 1 is the membrane surface SEM figure of the embodiment of the invention 1 preparation.
Fig. 2 is the barrier film xsect SEM figure of the embodiment of the invention 1 preparation.
The flexible packing lithium ion secondary battery of Fig. 3 for using the embodiment of the invention 1 barrier film to make carries out the 5C charging, the loop test comparison diagram of 15C discharge.
The flexible packing lithium ion secondary battery of Fig. 4 for using the embodiment of the invention 1 barrier film to make carries out the 5C charging, the cycle life test pattern of 20C discharge.
The flexible packing lithium ion secondary battery group of Fig. 5 for using the embodiment of the invention 1 barrier film to make carried out the 6C charging, the loop test comparison diagram of 10C discharge.
Embodiment
Below be to specify membranous making method provided by the invention and performance comparison.
Embodiment 1
Pvdf (PVDF) material 10kg, N-Methyl pyrrolidone (NMP) solvent 20kg are mixed, and controlled temperature disperses in dual-screw-stem machine for 90 ℃, through Melt Pump, extrudes at the mouth die head, gets into gel formation film in the water.Then, above-mentioned packaging film feeding is got in the extraction tank, water extracts solvent, thereby forms the film of vesicular structure.At last, through warm air drying, cutting into width afterwards is 125mm with above-mentioned porous membrane, and thickness is 22 μ m, destatics the back and accomplishes rolling.Recording air penetrability is 150 seconds/100CC.
Embodiment 2
Polysulfones (PS) material 10kg, N-Methyl pyrrolidone (NMP) solvent 25kg, lithium chloride (LiCl) 0.3kg are mixed, and controlled temperature disperses in dual-screw-stem machine for 100 ℃, through Melt Pump, extrudes at the mouth die head, gets into gel formation film in the water.Then, above-mentioned packaging film feeding is got in the extraction tank, water extracts solvent and inorganic salt, thereby forms the film of vesicular structure.At last, through warm air drying, cutting into width afterwards is 125mm with above-mentioned porous membrane, and thickness is 30 μ m, destatics the back and accomplishes rolling.Recording air penetrability is 120 seconds/100CC.
Embodiment 3
Pvdf (PVDF) material 10kg, triethyl phosphate (TEP) solvent 30kg are mixed, and controlled temperature disperses in dual-screw-stem machine for 90 ℃, through Melt Pump, extrudes at the mouth die head, gets into gel formation film in the water.Then, above-mentioned packaging film feeding is got in the extraction tank, water extracts solvent, thereby forms the film of vesicular structure.At last, through warm air drying, cutting into width afterwards is 125mm with above-mentioned porous membrane, and thickness is 22 μ m, destatics the back and accomplishes rolling.Recording air penetrability is 150 seconds/100CC.
Embodiment 4
Make barrier film according to the method among the embodiment 1, different is to change pvdf (PVDF) into pvdf-R 1216 (PVDF-HFP).
Embodiment 5
Make barrier film according to the method among the embodiment 1, different is to change pvdf (PVDF) into pvdf-trifluorochloroethylene (PVDF-CTFE).
Embodiment 6 preparation soft packaging lamination lithium-ion secondary celies.
Make multiplying power power-type lithium ion secondary cell according to known technology, wherein positive electrode material uses LiFePO 4, and negative material uses graphite, and electrolytic solution uses the carbonate solution of 1M lithium hexafluoro phosphate.The barrier film that barrier film uses embodiment 1 scheme to make.The sub-cell container of above-mentioned flexible-packaged lithium is 2.4Ah, and 1KHz exchanges internal resistance and is measured as 2.58m Ω.
Comparative Examples 1
Make soft packaging lamination lithium-ion secondary cell according to the method among the embodiment 6, different is to change barrier film into three layers of commodity barrier film of 20 μ m, PP/PE/PP that market is bought.The sub-secondary battery capacity of above-mentioned flexible-packaged lithium is 2.4Ah, and 1KHz exchanges internal resistance and is measured as 4.33m Ω.
Barrier film and flexible packing lithium ion battery performance test:
(1) membranous fundamental property and three layers of commodity barrier film of PP/PE/PP of embodiment 1 being made carry out the physicals contrast.
(2) flexible packing lithium ion secondary battery test: the flexible packing lithium ion secondary battery of making in embodiment 4 and the Comparative Examples 1 is carried out big electric current high-rate charge-discharge capability test.Wherein charging current is 5C (12.5A), and discharging current is 15C (37.5A).
(3) the big electric current high-rate charge-discharge capability of flexible packing lithium ion secondary battery cycle life test.Wherein charging current is 5C (12.5A), and discharging current is 20C (50A).
(4) 3 cells of flexible packing lithium ion secondary battery compose in parallel power brick, do not add any holding circuit.Carry out big electric current high-rate charge-discharge capability test.Wherein charging current is 6C (50A), and discharging current is 10C (75A).
Test result:
(1) table 1 carries out the physicals contrast for membranous fundamental property and three layers of commodity barrier film of PP/PE/PP that embodiment 1 makes.
Table 1
Embodiment 1 preparation barrier film Commodity PP/PE/PP barrier film
Material The PVDF individual layer Three layers of PP/PE/PP are compound
Thickness ?22μm 20μm
Internal structure Three-dimensional mesh Stretchable holes
Air penetrability * 150 seconds/100CC 400-500 second/100CC
Porosity ?60% 43%
The aperture ?0.1-1.0μm 0.1-0.2μm
*: the TP that adopts ASTM D 737-2004 textile fibres air penetrability
Show that according to test result barrier film porosity and the vesicular structure of embodiment 1 is good among the present invention, improved the transmissibility of ion in barrier film significantly, for the big electric current high power charging-discharging of lithium-ion secondary cell provides guarantee.
(2) as shown in Figure 3, Fig. 3 carries out the 5C charging for flexible packing lithium ion secondary battery, the loop test comparison diagram of 15C discharge.The result shows that the battery made from barrier film of the present invention charges at 5C, and 15C discharge-rate test performance is good, and capacity attenuation is slow after 300 circulations, still remains on more than 80% of initial capacity.Performance obviously is better than the battery that Comparative Examples 1 barrier film is made.
(3) as shown in Figure 4, Fig. 4 is the flexible-packed battery that the embodiment of the invention 1 barrier film is made, and carries out the 5C charging, the cycle life test pattern of 20C discharge.The result shows that the battery made from barrier film of the present invention charges at 5C, and 20C discharge-rate test performance is good, and 1000 times circulation back capacity attenuation is slow, still remains on more than 80% of initial capacity.Significantly improved the cycle life performance of lithium-ion secondary cell.
(4) as shown in Figure 5, Fig. 5 composes in parallel power brick for 3 cells of flexible packing lithium ion secondary battery, carries out big electric current high-rate charge-discharge capability test pattern.The result shows the battery that barrier film of the present invention is made, compose in parallel power brick after, in the 6C charging, 10C discharge-rate test performance is good, capacity attenuation is slow after 1000 circulations, still remains on more than 80% of initial capacity.Performance obviously is better than the batteries in parallel connection bag that Comparative Examples 1 barrier film is made.

Claims (37)

1. method for preparing porous-film comprises:
A) polymkeric substance and solvent are carried out blending dispersion, make slurry;
B) slurry in a) is flowed out through the narrow shape break joint in the gel groove, form film;
C) with b) in film introduce in the extraction tank and carry out solvent exchange, form porous membrane;
D) porous membrane is carried out drying.
2. the method for preparing porous-film as claimed in claim 1; It is characterized in that; Said polymkeric substance is selected from can be by the polymkeric substance of the dissolution with solvents of using simultaneously, comprises in fluoropolymer, Rohm tech inc (PMMA), polyacrylonitrile (PAN), polyoxyethylene (PEO), polysulfones (PS), polyethersulfone (PES) and the SE (PVC) one or more.
3. the method for preparing porous-film as claimed in claim 2 is characterized in that, fluoropolymer is selected from pvdf (PVDF) and contains in the multipolymer of pvdf one or both.
4. the method for preparing porous-film as claimed in claim 3 is characterized in that, the multipolymer that contains pvdf is selected from one or both in pvdf-R 1216 (PVDF-HFP) and pvdf-trifluorochloroethylene (PVDF-CTFE) multipolymer.
5. the method for preparing porous-film as claimed in claim 1 is characterized in that, it is the organic solvent more than 150 ℃ that said solvent is selected from boiling point.
6. the method for preparing porous-film as claimed in claim 5; It is characterized in that; Said organic solvent is selected from N-Methyl pyrrolidone (NMP), DMAC N,N (DMAC), N, one or more in dinethylformamide (DMF), methyl-sulphoxide (DMSO) and the triethyl phosphate (TEP).
7. the method for preparing porous-film as claimed in claim 6 is characterized in that, said organic solvent is N-Methyl pyrrolidone (NMP).
8. the method for preparing porous-film as claimed in claim 1 is characterized in that, the mass ratio of solvent and polymkeric substance is 1~4.
9. the method for preparing porous-film as claimed in claim 8 is characterized in that, the mass ratio of solvent and polymkeric substance is 1.5~3.
10. the method for preparing porous-film as claimed in claim 1 is characterized in that, a) step comprises inorganic salt and polymkeric substance and solvent are carried out blending dispersion, makes slurry.
11. the method for preparing porous-film as claimed in claim 10 is characterized in that said inorganic salt are for can be dissolved in the inorganic salt that boiling point is an organic solvent more than 150 ℃.
12. the method for preparing porous-film as claimed in claim 11 is characterized in that, said inorganic salt are lithium chloride (LiCl).
13. the method for preparing porous-film as claimed in claim 12 is characterized in that, the mass ratio of inorganic salt and solvent is 0.005~0.1.
14. the method for preparing porous-film as claimed in claim 13 is characterized in that, the mass ratio of inorganic salt and solvent is 0.01~0.05.
15. the method for preparing porous-film as claimed in claim 14 is characterized in that, the temperature that polymkeric substance and solvent and inorganic salt carry out blending dispersion is 50-150 ℃.
16. the method for preparing porous-film as claimed in claim 15 is characterized in that, the temperature that polymkeric substance and solvent and inorganic salt carry out blending dispersion is 60-100 ℃.
17. the method for preparing porous-film as claimed in claim 16 is characterized in that, step a) comprises carries out blending dispersion with polymkeric substance and solvent and inorganic salt through multiple screw extruder, forms slurry.
18. the method for preparing porous-film as claimed in claim 17 is characterized in that, step b) comprises slurry through port mould mode is flowed out.
19. the method for preparing porous-film as claimed in claim 18 is characterized in that, step b) comprises fluid introduced in the gel groove and forms porous membrane.
20. the method for preparing porous-film as claimed in claim 1 is characterized in that, the coagulant liquid in the step b) in the gel groove is a water.
21. the method for preparing porous-film as claimed in claim 20 is characterized in that, the temperature of coagulant liquid is 20-95 ℃ in the gel groove.
22. the method for preparing porous-film as claimed in claim 1 is characterized in that, the extraction liquid in the step c) in the extraction tank is a water.
23. the method for preparing porous-film as claimed in claim 1 is characterized in that, at step b), c) or d) in said film or porous-film are stretched.
24. the method for preparing porous-film as claimed in claim 23 is characterized in that, it is 1: 1.03 to 1: 1.3 that film or porous-film are carried out the tensile stretch ratio.
25., also further comprise the step that reclaims solvent coagulant liquid and the extraction liquid after using like the arbitrary described method for preparing porous-film of claim 1~24.
26. the method for preparing porous-film as claimed in claim 25 is characterized in that, the method that reclaims solvent is for adopting distil process with water and separated from solvent.
27., also further comprise the step that reclaims inorganic salt coagulant liquid and the extraction liquid after using like the arbitrary described method for preparing porous-film of claim 9~12.
28. a porous-film comprises by the film with vesicular structure of polymer formation, it is characterized in that, said vesicular structure is the three dimensional network pore structure that connects each other.
29. porous-film as claimed in claim 28; It is characterized in that; Said polymkeric substance is selected from can be by the polymkeric substance of the dissolution with solvents of using simultaneously, comprises in fluoropolymer, Rohm tech inc (PMMA), polyacrylonitrile (PAN), polyoxyethylene (PEO), polysulfones (PS), polyethersulfone (PES) and the SE (PVC) one or more.
30. porous-film as claimed in claim 29 is characterized in that, said fluoropolymer is selected from pvdf (PVDF) and contains in the multipolymer of pvdf one or both.
31. the method for preparing porous-film as claimed in claim 30 is characterized in that, the multipolymer that contains pvdf is selected from one or both in pvdf-R 1216 (PVDF-HFP) and pvdf-trifluorochloroethylene (PVDF-CTFE) multipolymer.
32., it is characterized in that the thickness of porous-film is 10~400 μ m like the arbitrary described porous-film of claim 28~31.
33. porous-film as claimed in claim 32 is characterized in that, the thickness of porous-film is 20~100 μ m.
34., it is characterized in that the aperture of porous-film is 0.01~5 μ m like the arbitrary described porous-film of claim 28~31.
35. porous-film as claimed in claim 34 is characterized in that, the aperture of porous-film is 0.01~2 μ m.
36., it is characterized in that the porosity of porous-film is 30~80% like the arbitrary described porous-film of claim 28~31.
37. porous-film as claimed in claim 36 is characterized in that, the porosity of porous-film is 50~70%.
CN2010105515947A 2010-11-13 2010-11-13 Porous membrane and preparation method thereof Pending CN102464803A (en)

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