CN101212035B - Battery isolating film and method for producing the same - Google Patents
Battery isolating film and method for producing the same Download PDFInfo
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- CN101212035B CN101212035B CN200610170396XA CN200610170396A CN101212035B CN 101212035 B CN101212035 B CN 101212035B CN 200610170396X A CN200610170396X A CN 200610170396XA CN 200610170396 A CN200610170396 A CN 200610170396A CN 101212035 B CN101212035 B CN 101212035B
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Abstract
The invention provides a battery diaphragm. The diaphragm comprises a substrate; the substrate is provided with a via, wherein, the substrate has polyimide; the channel of the via has polyolefin. The battery diaphragm obtained from the embodiment of the invention has an excellent high temperature resistance and burst can not be happened by heating to 400 DEG C; all the heat shrinkage are not more than 1.3 percent at 400 DEG C, which is far less than the heat shrinkage of 5 percent in prior art; the average diameter of pores and porosity all meet the demand of conductivity; a suitable and fine air permeability is provided; the heat shrinkage is also far less than the battery diaphragm in prior art. The battery made by the battery diaphragm provided by the invention has excellent high temperature resistance that unsafe phenomena of explosion, smoking, firing and liquid leaking can not happen even under a high temperature of 150 DEG C.
Description
Technical field
The invention relates to a kind of battery diaphragm and preparation method thereof.
Background technology
Lithium rechargeable battery is with advantages such as its high-energy-density, high voltage, little, in light weight, the memoryless property of volume, obtained huge development over past ten years, become one of main energy sources of communication class electronic product, yet lithium rechargeable battery also exists potential safety hazard.At high temperature, short circuit, cross charge and discharge, vibrate, under the situations such as extruding and bump, battery temperature will be raise, and then initiation inside lithium ion cell material generation chemical reaction, reactions such as thermal decomposition as SEI film on the thermal decomposition of the thermal decomposition of positive electrode, electrolyte and the negative pole, more violent reaction will take place with solvent in the product of above-mentioned reaction, these reactions will discharge a large amount of heat, make that system temperature constantly rises, inner pressure of battery raises, and may cause catching fire, exploding of battery.Therefore, improve the key that lithium ion battery security is the research and development lithium ion battery.
Battery diaphragm plays the effect that stops the direct contact short circuit of both positive and negative polarity in lithium ion battery.In order to improve the fail safe of battery, not only require battery diaphragm can stop the direct contact short circuit of both positive and negative polarity at normal temperatures, also requiring at high temperature simultaneously, this battery diaphragm also can stop the direct contact short circuit of both positive and negative polarity.But battery diaphragm commonly used now as polyethylene, the very difficult integrality that guarantees under the high temperature of polypropylene, often occurs in the safety tests such as stove heat shrinking the problem that causes internal short-circuit, initiation thermal runaway because of battery diaphragm.Therefore, the resistance to elevated temperatures of raising battery diaphragm is to improve the key of lithium rechargeable battery high temperature safe performance.
The fail safe of lithium ion battery is mainly by positive electrode, electrolyte-solvent species and membrane properties decision, yet, the raising of the thermal stability of SEI film is very limited on positive electrode, electrolyte-solvent and the negative pole, therefore, the thermal stability of raising battery diaphragm just becomes the important channel of improving battery security.Under lower temperature (140 ℃), lithium ion battery safety is to realize by the blocking function of barrier film to electric current, because low Tg (less than the 140 ℃) polymer as barrier film will melt between 100-140 ℃, cause micropore canals to be closed, impedance increases sharply and makes the electric current blocking.The polyethylene (PE) commonly used now and the self-closing temperature of polypropylene (PP) barrier film are respectively about 130-140 ℃ and 170 ℃.Under higher temperature, even behind the bore closure of barrier film, because other reasons causes battery temperature to continue to raise, the heat resisting temperature that surpasses barrier film, barrier film will be completely melted, destroy, cause positive pole, negative pole directly to contact and short circuit, thereby cause strong exothermic reaction more, cause that battery catches fire, explodes.Battery diaphragm now commonly used such as PE, PP fusion temperature all are lower than 200 ℃, can't provide safety guarantee under the higher temperature (200-500 ℃) to battery.
Patent CN 1725524A discloses a kind of separator for non-aqueous electrolyte battery that is formed by the micro-porous film of stacked polyolefin layer and refractory layer, and refractory layer is to be that polyamide, polyimides or polyamidoimide more than 180 ℃ forms by fusing point.Though the method can be improved the thermal stability of barrier film, yet, because the base material of barrier film remains polyolefine material, when (180 ℃), polyolefine material melts when temperature surpasses the fusing point of polyolefine material, and the barrier film base material is destroyed, the refractory layer polymer that the huge difference of thermal coefficient of expansion will cause depending on polyolefin substrate comes off thereupon, and the thickness of refractory layer polymer is the 1-4 micron, and cutting resistance is weaker than the thick film (thickness 10-25 micron) of identical material.
CN 1512607A provides a kind of improved perforated membrane, and this perforated membrane contains ethylene-propylene-ethylidene norbornene terpolymer, by three's crosslinked action raising intensity and heat resistance.But because used ultra-high molecular weight polyethylene and norborene to improve cost, and be that the traditional thermoplastic PE/PP of employing is main, percent thermal shrinkage is relatively large.
Present existing battery diaphragm is base material usually with the polyolefine material, because the fusing point of polyolefine material is low, therefore when temperature surpasses polyolefine material, polyolefine material melts, barrier film is destroyed, cause positive pole, negative pole directly to contact and short circuit, thereby cause strong exothermic reaction more, cause that battery catches fire, explodes.
Summary of the invention
The object of the present invention is to provide a kind of good heat resistance, mechanical strength height, battery diaphragm and manufacture method thereof that cyclicity is good.
The invention provides a kind of battery diaphragm, this barrier film comprises base material and the hole that is distributed on the base material, and wherein, described base material contains polyimides, contains polyolefin layer in the hole on the base material.
The invention provides a kind of preparation method of battery diaphragm, this method comprises containing base material, solvent, pore-forming material and polyolefinic solution film forming, removes the pore-forming material then, and wherein, described base material contains polyimides, contains polyolefin layer in the hole on the base material.
Battery diaphragm provided by the invention is owing to adopt novel fire resistant material polyimides as base material, thereby has excellent chemical stability, heat-resisting quantity, excellent permeability, high mechanical properties.The battery diaphragm that obtains in the embodiment of the invention is heated to 400 ℃ of high temperature and does not also break; Battery diaphragm all is not more than 1.2% at 400 ℃ percent thermal shrinkage, 5% percent thermal shrinkage in the prior art; And suitable good air permeability is arranged, and percent thermal shrinkage is also much smaller than battery diaphragm of the prior art.
Embodiment
The invention provides a kind of battery diaphragm, this barrier film comprises base material and the hole that is distributed on the base material, and wherein, described base material contains polyimides, contains polyolefin layer in the hole on the base material.
Among the present invention, described polyimides can be the polymer that contains imide group in the various repetitives, and under the preferable case, described polyimides is the polyimides with following structural formula:
Wherein, R
1And R
2Identical or different, can be various aliphat or aromatic hydrocarbyl, the value of the n of the degree of polymerization is 50～10000.
Polyimides of the present invention can in all sorts of ways and obtain, and for example, can be commercially available, preferred fusing point is at 400-700 ℃ aromatic polyimide, further preferred, fusing point also can obtain by prepared in various methods at 500-600 ℃ aromatic polyimide.For example, can obtain by the condensation reaction between polynary organic carboxyl acid or derivatives thereof and the organic diamine.Described polynary organic carboxyl acid derivative is selected from binary organic acid acid anhydride, the organic acyl chlorides of quaternary, quaternary organic acid esters.Because quaternary organic carboxyl acid, the organic acyl chlorides of quaternary, quaternary organic acid esters and organic diamine can produce micromolecular compound when reacting, bring inconvenience for the preparation of battery diaphragm, therefore, the preferred described polyimides of the present invention is preferably the product of binary organic acid acid anhydride and organic diamine.Described binary organic acid acid anhydride can be various saturated and/or unsaturated binary organic acid acid anhydrides, and described organic diamine can be the various diamines that contain two secondary amino groups.Contain benzene ring structure in preferred described binary organic acid acid anhydride of the present invention and/or the organic diamine, for example, described binary organic acid acid anhydride can be selected from pyromellitic acid anhydride, 3,3 ', 4,4 '-biphenyl tetracarboxylic dianhydride, 2,2 ', 3,3 '-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, 1,2,5,6-naphthalene tetracarboxylic acid dianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride, 1,2,4,5-naphthalene tetracarboxylic acid dianhydride, 1, two (trifluoromethyl)-2,3 of 4-, 5,6-benzene tertacarbonic acid dianhydride, 3,3 ', 4,4 '-benzophenone tetracarboxylic dianhydride, 1,2 ', 3,3 '-benzophenone tetracarboxylic dianhydride, 2,6-dichloronaphtalene-1,4,5, the 8-tetracarboxylic dianhydride, 2,7-dichloronaphtalene-1,4,5, the 8-tetracarboxylic dianhydride, 2,3,6,7-Tetrachloronaphthalene-2,4,5, the 8-tetracarboxylic dianhydride, luxuriant and rich with fragrance-1,8,9, the 10-tetracarboxylic dianhydride, benzene-1,2,3, the 4-tetracarboxylic dianhydride, pyrazine-2,3,5, among the 6-tetracarboxylic dianhydride one or more are preferably equal benzene tertacarbonic acid's dianhydride, 3,3, ' 4,4 '-biphenyl tetracarboxylic dianhydride, 2,2 ', 3,3 '-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, 3,3 ', 4, one or more in 4 '-benzophenone tetracarboxylic dianhydride.
Described organic diamine is selected from 4; 4 '-diaminodiphenyl ether; 4; 4 '-diaminobenzophenone; 3; 3 '-dimethyl-4,4 '-diaminobenzophenone; 3,3 '-two chloro-4; 4 '-diaminobenzophenone; m-phenylene diamine (MPD); p-phenylenediamine (PPD); 4 '-di-2-ethylhexylphosphine oxide (neighbour-chloroaniline); 3; 3 '-dichloro diphenylamine; 3,3 '-sulfonyl diphenylamines; 1, the 5-diaminonaphthalene; 2; 2 '-two (4-amino-phenols); 4; 4 '-benzidine; 4,4 '-methylene dianiline (MDA); 4,4 '-sulfenyl diphenylamines; 4; 4 '-isopropylidene diphenylamines; 3; 3 '-dimethylbenzidine; 3,3 '-dimethoxy benzidine; 3,3 '-dicarboxylate biphenyl amine; 2; the 4-diaminotoluene; 2; the 5-diaminotoluene; 2,4-diaminourea-5-chlorotoluene; 2, one or more in 4-diaminourea-6-chlorotoluene; be preferably 4; 4 '-diaminodiphenyl ether (ODA); 4,4 '-diaminobenzophenone; p-phenylenediamine (PPD); 4, one or more in 4 '-benzidine.
Among the present invention, described polyolefin layer is made up of at 100-130 ℃ polyolefin vitrification point, and described polyolefin can be selected from polyethylene and/or polypropylene, and preferred molecular weight is the polyethylene of 80000-150000.The effect in inaccessible barrier film duct is played in the adding of polyolefin layer, and when temperature surpassed 130 ℃, polyolefin layer melted, inaccessible duct is opened circuit battery, and temperature can not continue to rise, after treating that temperature descends, polyolefin layer solidifies, and recover in the duct, and barrier film recovers normal condition, guarantee that by this structure barrier film can not melt because of temperature is too high, avoided positive pole, negative pole directly to contact and short circuit, thereby caused strong exothermic reaction more, caused that battery catches fire, explodes.
Among the present invention, there is no particular limitation to the density in the thickness of barrier film, the size that is distributed in the hole on the base material and hole for described battery diaphragm, as long as can satisfy the requirement of lithium rechargeable battery to battery diaphragm.Under the preferable case, the average diameter in described hole is preferably the 0.01-0.5 micron, more preferably the 0.03-0.3 micron; Described porosity is preferably 30-60 volume %, more preferably 40-50 volume %; The thickness of described barrier film is the 12-30 micron, more preferably the 15-24 micron.
The preparation method of battery diaphragm provided by the invention comprises and will contain the solution film forming of base material, solvent, pore-forming material, remove the pore-forming material, obtain perforated membrane, then polyolefin solution is coated on the perforated membrane and under vacuum, heats, the cooling phase-splitting, wherein, described base material contains polyimides, contains polyolefin layer in the hole on the base material.
There is no particular limitation to polyimides, pore-forming material, solvent and polyolefinic feeding quantity in the present invention, specifically according to the size decision in required hole density of battery diaphragm and hole.Under the preferable case, the weight ratio of described polyimides and pore-forming material is 100: 20-60, more preferably 100: 40-50, the weight ratio of described polyimides and solvent is 8-15: 100,9-12 more preferably: 100, described polyimides and polyolefinic weight ratio are 100: 5-50, further preferred weight ratio is 100: 10-30.
The polyimides that the present invention selects for use is a fusing point at 400-700 ℃ aromatic polyimide, and preferred fusing point also can obtain by the condensation reaction between polynary organic carboxyl acid or derivatives thereof and the organic diamine at 500-600 ℃ aromatic polyimide.
Therefore, the preparation method of battery diaphragm provided by the invention can also realize by following manner: polynary organic carboxyl acid or derivatives thereof, organic diamine, pore-forming material are contacted with solvent, obtain the solution of homogeneous, then with solution film forming, remove the pore-forming material then, described polynary organic carboxyl acid or derivatives thereof is quaternary organic carboxyl acid, the organic acyl chlorides of quaternary, quaternary organic acid esters or binary organic acid acid anhydride.The mol ratio of described polynary organic carboxyl acid or derivatives thereof and organic diamine is 0.99-1.05: 1,1.00-1.02 more preferably: 1, the total amount of described polynary organic carboxyl acid or derivatives thereof and organic diamine and the weight ratio of pore-forming material are 100: 20-60, be preferably 100: 30-50, the weight ratio of described solvent and polynary organic carboxyl acid or derivatives thereof and organic diamine polyimides is 100: 8-15 is preferably 100: 9-12.The temperature that described polynary organic carboxyl acid or derivatives thereof, organic diamine, pore-forming material contact with solvent is 0-90 ℃, and the time of contact is 4-24 hour.
Described binary organic acid acid anhydride can be selected from pyromellitic acid anhydride, 3,3 ', 4,4 '-biphenyl tetracarboxylic dianhydride, 2,2 ', 3,3 '-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, 1,2,5,6-naphthalene tetracarboxylic acid dianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride, 1,2,4,5-naphthalene tetracarboxylic acid dianhydride, 1, two (trifluoromethyl)-2 of 4-, 3,5,6-benzene tertacarbonic acid dianhydride, 3,3 ', 4,4 '-benzophenone tetracarboxylic dianhydride, 1,2 ', 3,3 '-benzophenone tetracarboxylic dianhydride, 2,6-dichloronaphtalene-1,4,5, the 8-tetracarboxylic dianhydride, 2,7-dichloronaphtalene-1,4,5, the 8-tetracarboxylic dianhydride, 2,3,6,7-Tetrachloronaphthalene-2,4,5, the 8-tetracarboxylic dianhydride, luxuriant and rich with fragrance-1,8,9, the 10-tetracarboxylic dianhydride, benzene-1,2,3, the 4-tetracarboxylic dianhydride, pyrazine-2,3,5, among the 6-tetracarboxylic dianhydride one or more are preferably equal benzene tertacarbonic acid's dianhydride, 3,3, ' 4,4 '-biphenyl tetracarboxylic dianhydride, 2,2 ', 3,3 '-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, 3,3 ', 4, one or more in 4 '-benzophenone tetracarboxylic dianhydride.
Described organic diamine is selected from 4; 4 '-diaminodiphenyl ether; 4; 4 '-diaminobenzophenone; 3; 3 '-dimethyl-4,4 '-diaminobenzophenone; 3,3 '-two chloro-4; 4 '-diaminobenzophenone; m-phenylene diamine (MPD); p-phenylenediamine (PPD); 4 '-di-2-ethylhexylphosphine oxide (neighbour-chloroaniline); 3; 3 '-dichloro diphenylamine; 3,3 '-sulfonyl diphenylamines; 1, the 5-diaminonaphthalene; 2; 2 '-two (4-amino-phenols); 4; 4 '-benzidine; 4,4 '-methylene dianiline (MDA); 4,4 '-sulfenyl diphenylamines; 4; 4 '-isopropylidene diphenylamines; 3; 3 '-dimethylbenzidine; 3,3 '-dimethoxy benzidine; 3,3 '-dicarboxylate biphenyl amine; 2; the 4-diaminotoluene; 2; the 5-diaminotoluene; 2,4-diaminourea-5-chlorotoluene; 2, one or more in 4-diaminourea-6-chlorotoluene; be preferably 4; 4 '-diaminodiphenyl ether (ODA); 4,4 '-diaminobenzophenone; p-phenylenediamine (PPD); 4, one or more in 4 '-benzidine.
The reaction condition of described binary organic acid acid anhydride and organic diamine and method of operation have been conventionally known to one of skill in the art, do not repeat them here.
Among the present invention, described pore-forming material can be various inorganic crystal whiskers, and inorganic crystal whisker is selected from one or more in calcium sulfate crystal whiskers, potassium titanate crystal whisker, aluminium borate whisker, magnesium borate crystal whisker, alkali magnesium sulfate crystal whisker, magnesium hydroxide crystal whisker, Kocide SD whisker, silica whisker, alumina whisker, magnesia crystal whisker and the ZnOw.
Described solvent can be the various solvents that can dissolve base material and pore-forming material simultaneously and be easy to volatilize and remove.Among the present invention, described solvent can be to be various strong polarity nonionic solvent commonly used, be preferably N-2-methyl pyrrolidone (NMP), N, N-dimethylacetylamide (DMAC), N, in dinethylformamide (DMF), dimethyl sulfoxide (DMSO) (DMSO), m-cresol, oxolane, the methyl alcohol one or more, more preferably one or more among NMP, DMAC, the DMF.
Among the present invention, the method for described film forming can adopt conventional method such as dried film build method and wet film build method.For example, can be by solution be smeared into desired thickness.Described smearing can be realized by the whole bag of tricks, for example can use spreader.The same with conventional film build method, solution smeared into desired thickness after, again solvent is removed, obtain non-porous film, the pore-forming material in the non-porous film is removed promptly got battery diaphragm of the present invention then.
Among the present invention, describedly remove the method desolvate and concrete operations for conventionally known to one of skill in the art, the preferred method of heating that adopts is removed solvent, and the temperature of heating is decided on the boiling point of solvent.
The method of described film forming can adopt conventional method such as dried film build method and wet film build method.For example, can be by solution be smeared into desired thickness.Described smearing can be realized by the whole bag of tricks, for example can use spreader.The same with conventional film build method, solution smeared into desired thickness after, obtain non-porous film, then the pore-forming material in the non-porous film is removed, obtain polyimide porous membrane.
When adopting binary organic acid acid anhydride and organic diamine to be the feedstock production polyimide base material, the preparation method of battery diaphragm of the present invention comprises that also the non-porous film that will remove behind the solvent carried out imidization reaction earlier before removing the pore-forming material, be converted into polyimides with polyamic acid.The reaction temperature of described imidizate is 270-350 ℃, and the reaction time is preferably 1-5 hour.Can directly heat up and also can adopt program mode to heat up to raise the temperature to 270-350 ℃, the present invention preferably adopts with 4-8 ℃/minute heating rate temperature programming to 270-350 ℃, so that the abundant imidizate of polyamic acid generates required polyimides.
Among the present invention, the pore-forming material is removed in the mode that adds solvent, and described solvent is selected from one or more in the acid solution of water and/or organic solvent, or in the alkaline solution of water and/or organic solvent one or more.For example, acid solution can be selected from one or more in hydrochloric acid solution, sulfuric acid solution, the salpeter solution, and alkaline solution can be selected from NaOH and/or potassium hydroxide solution.
Describedly remove the method desolvate and concrete operations for conventionally known to one of skill in the art, the preferred method of heating that adopts is removed solvent, and the temperature of heating is decided on the boiling point of solvent.Among the present invention, removing the temperature of desolvating is the temperature of removing that is lower than the boiling temperature of solvent and is lower than the pore-forming material, more is lower than the vitrification point of base material.
Among the present invention, barrier film forms after soaking the suction polyolefin by polyimide porous membrane, the described polyolefin of stating is made up of at 100-130 ℃ polyolefin vitrification point, is not particularly limited for the method for soaking suction, for example, coating is as the vistanex solution of fuse function on the polyimides micro-porous film, then this composite diaphragm is heated under vacuum, heating-up temperature is 120-180 ℃, and be 4-12 hour heating time, the polyolefin of molten state is entered among the duct, the cooling phase-splitting.
The following examples will the invention will be further described.
Embodiment 1
Present embodiment is used to illustrate battery diaphragm provided by the invention and preparation method thereof.
The pyromellitic acid anhydride (PMDA, the imperial desertification worker of Su sun Co., Ltd) and the 2450 weight portion diaminodiphenyl ethers (ODA, Shanghai test-run a machine three factories) of 2500 weight portions are synthesized polyamic acid solution; Again the magnesium hydroxide crystal whisker of the polyamic acid of 4950 weight portions and 1900 weight portions (M-HOW, this digests Co., Ltd Yingkou prestige) at the N of 49500 weight portions, is mixed in the N-dimethylacetylamide (DMAC, Shanghai Jingwei Chemical Co., Ltd.).Be coated on glass filming then, obtain thickness and be 0.4 millimeter sheet material, with this sheet material under 90 ℃, handle and removed solvent in 5 hours, with 6 ℃/minute heating rate temperature programmings to 320 ℃, heated 3 hours, carry out imidizate, obtain the polyimide film of inorganic hybridization, the thickness of this perforated membrane is 15 microns.
It is in 2 the aqueous hydrochloric acid solution 4 hours that this hybrid film is immersed pH, takes out film, washes repeatedly with appropriate amount of deionized water, occurs to there being chloride ion, and drying obtains polyimide porous membrane.
Molecular weight with 30 weight portions under vacuum (90Pa, 160 ℃) state is 100000, and vitrification point is 120 ℃ a polyethylene, inject the polyimide porous membrane of 100 weight portions, heat degasification in 6 hours, naturally cool to room temperature again, obtain battery diaphragm of the present invention thus.
Embodiment 2
Present embodiment is used to illustrate battery diaphragm provided by the invention and preparation method thereof.
The bibenzene tetracarboxylic dianhydride (the imperial desertification worker of Su sun Co., Ltd) and the 2500 weight portion diaminobenzophenones (Shanghai test-run a machine three factories) of 2500 weight portions are synthesized polyamic acid solution; Again the alkali magnesium sulfate crystal whisker of the polyamic acid of 5000 weight portions and 2000 weight portions (this digests Co., Ltd Yingkou prestige) is mixed in the N-2-of 42000 weight portions dimethyl pyrrolidone (Shanghai Jingwei Chemical Co., Ltd.).Be coated on glass filming then, obtain thickness and be 0.4 millimeter sheet material, with this sheet material under 90 ℃, handle and removed solvent in 5 hours, with 7 ℃/minute heating rate temperature programmings to 310 ℃, heated 3 hours, carry out imidizate, obtain the polyimide film of inorganic hybridization, the thickness of this perforated membrane is 15 microns.
It is in 2 the aqueous sulfuric acid 4 hours that this hybrid film is immersed pH value, takes out film, washes repeatedly with appropriate amount of deionized water, and to there being the chloride ion appearance, drying obtains polyimide porous membrane.
Molecular weight with 20 weight portions under vacuum (90Pa, 150 ℃ under) state is 100000, and vitrification point is 120 ℃ a polyethylene, inject the polyimide porous membrane of 100 weight portions, heat degasification in 6 hours, naturally cool to room temperature again, obtain battery diaphragm of the present invention thus.
Embodiment 3
Present embodiment is used to illustrate battery diaphragm provided by the invention and preparation method thereof.
Benzophenone tetracarboxylic acid dianhydride (the imperial desertification worker of Su sun Co., Ltd) and 2500 weight portion p-phenylenediamine (PPD) (Shanghai test-run a machine three factories) with 2500 weight portions synthesize polyamic acid solution; Again the ZnOw of the polyamic acid solution of 5000 weight portions and 1800 weight portions (this digests Co., Ltd Yingkou prestige) is mixed in the dimethyl sulfoxide (DMSO) (Shanghai Jingwei Chemical Co., Ltd.) of 47000 weight portions.Be coated on glass filming then, obtain thickness and be 0.4 millimeter sheet material, with this sheet material under 90 ℃, handle and removed solvent in 5 hours, with 5 ℃/minute heating rate temperature programmings to 330 ℃, heat and carried out imidizate in 2 hours, obtain the polyimide film of inorganic hybridization, the thickness of this perforated membrane is 15 microns.
It is in 2 the aqueous solution of nitric acid 4 hours that this hybrid film is immersed pH, takes out film, washes repeatedly with proper amount of deionized water, occurs to there being chloride ion, and drying obtains polyimide porous membrane.
At vacuum (90Pa, under 150 ℃) molecular weight with 25 weight portions under the state is 100000, vitrification point is the polyimide porous membrane that 120 ℃ polyethylene solution injects 100 weight portions, heats degasification in 6 hours, naturally cool to room temperature again, obtain battery diaphragm of the present invention thus.
Comparative Examples 1
Prepare battery diaphragm according to CN 1512607A embodiment 1 described method, the thickness of barrier film is 16 microns.
Embodiment 4-6
Adopt following method to measure the porosity of the battery diaphragm that embodiment 1-3 makes, average diameter, air permeability, thickness, closed temperature/melt temperature, thermal endurance and the heat-shrinkable in hole respectively, measurement result is as shown in table 1 below.
Porosity: adopt the method for testing test of this area routine: the square sample of downcutting certain-length from microporous barrier, measure its volume (cubic centimetre) and weight (gram), calculate by following formula: porosity (%)=100 * (1-weight/(resin density * volume))
The average diameter in hole: determine according to the pore diameter distribution curve that the BJH method obtains by the ammonia absorption/desorption type specific area/distribution of pores tester ASAP2010 that makes by Shimadzu Corp.
Thickness: directly measure with hand formula THICKNESS GAUGE FOR THE MEASUREMENT OF THIN FOILS (model C H-1-S, Shanghai six water chestnut instrument plants).
Closed temperature/melt temperature: measure with the gas permeability device.In the gas permeability test process, keep inlet pressure constant, the barrier film temperature that slowly raises (less than 1 ℃/minute), the transmission rates of measurement gas.Temperature when almost not having gas permeation is exactly the closed temperature of barrier film.
Air permeability: measure according to JIS P8117.
Heat-shrinkable: with lateral length is L
0The battery diaphragm nature be placed in the baking oven of 150 ℃ and 400 ℃ and kept respectively 1 hour, measure lateral length L then
1, then
Thermal endurance: adopt the thermal endurance of the described heat-resisting membrane ruptures method test battery barrier film of CN 1512607A, the heating rate of different is battery is 10 ℃/minute, is warming up to 400 ℃.
Comparative Examples 2
According to the described method of embodiment 4-6, the porosity of the battery diaphragm that mensuration Comparative Examples 1 makes, average diameter, air permeability, thickness, closed temperature/melt temperature, thermal endurance and the heat-shrinkable in hole, measurement result is as shown in table 1 below.
Table 1
| The embodiment numbering | Embodiment 4 | Embodiment 5 | Embodiment 6 | Comparative Examples 2 |
| Thickness (micron) | 15 | 15 | 15 | 16 |
| The average diameter in hole (micron) | 0.305 | 0.298 | 0.302 | 0.246 |
| Porosity (volume %) | 50 | 48 | 47 | 48 |
| Air permeability (second/100cc) | 420 | 400 | 370 | 350 |
| Percent thermal shrinkage (400 ℃, %) | 1.2 | 1.2 | 1.2 | 5 |
| Barrier film thermal fracture (400 ℃) | Crack-free | Crack-free | Crack-free | Break |
The result who from last table 1, provides as can be seen, the battery diaphragm resistance to elevated temperatures excellence that obtains in the embodiment of the invention is heated to 400 ℃ of high temperature and does not also break; All be not more than 1.3% at 400 ℃ percent thermal shrinkages, percent thermal shrinkage much smaller than of the prior art 5%; The average diameter in hole and porosity all satisfy the conductance requirement, and suitable good air permeability is arranged, and percent thermal shrinkage is also much smaller than battery diaphragm of the prior art.
Embodiment 7-9
Make the LP043450 size battery with the battery diaphragm that embodiment 1-3 makes, above-mentioned battery is carried out the high-temperature behavior test, described high-temperature behavior test is the test of 150 ℃ of stove heat, the method of 150 ℃ of stove heat test is charged to 100% Charging state for above-mentioned battery is carried out 1C, be placed in the baking oven, oven temperature is elevated to 150 ℃ with 5 ℃/minute from room temperature, and wherein cell voltage falls greater than 0.2 volt and is considered as short circuit.Test result is as shown in table 2.
Comparative Examples 3
According to the described method of embodiment 7-9, make the LP043450 size battery with the battery diaphragm that Comparative Examples 1 makes, carry out the high-temperature behavior test, the result is as shown in table 2.
Table 2
| The barrier film source | Short-circuit conditions | The thermal runaway situation |
| Embodiment 1 | Not short circuit | Do not explode, smolder, catch fire, leakage |
| Embodiment 2 | Not short circuit | Do not explode, smolder, catch fire, leakage |
| Embodiment 3 | Not short circuit | Do not explode, smolder, catch fire, leakage |
| Comparative Examples 1 | Short circuit | Blast |
From the result of last table 2 as can be seen, the battery that makes with battery diaphragm provided by the invention has outstanding high temperature resistance, even also do not blast under 150 ℃ of high temperature, smolder, catch fire, dangerous phenomenon such as leakage.
Claims (15)
1. battery diaphragm, this barrier film is made of the polyolefin layer that the duct of base material with through hole and described through hole contains, described base material is made of polyimides, described polyolefinic vitrification point is 100-130 ℃, the diameter of described through hole is the 0.01-0.5 micron, porosity is 30-60 volume %, and the thickness of barrier film is the 12-30 micron.
2. battery diaphragm according to claim 1, wherein, described polyimides and polyolefinic weight ratio are 100: 5-50.
3. battery diaphragm according to claim 1 and 2, wherein, described polyimides is the polyimides with following structural formula:
Wherein, R
1And R
2Identical or different, be selected from aliphat or aromatic hydrocarbyl, the value of n is 50～10000.
4. battery diaphragm according to claim 1 and 2, wherein, the fusing point of described polyimides is 400-700 ℃.
5. the preparation method of a battery diaphragm, this method comprises and will contain the solution film forming of base material, solvent, pore-forming material, remove the pore-forming material, obtain perforated membrane, then polyolefin solution is coated on the perforated membrane and under vacuum, heats, it is characterized in that, described base material is made of polyimides, contain polyolefin layer in the through hole on the base material, described polyolefinic vitrification point is 100-130 ℃, the diameter of described through hole is the 0.01-0.5 micron, and porosity is 30-60 volume %, and the thickness of barrier film is the 12-30 micron.
6. method according to claim 5 wherein, is coated on polyolefin solution on the perforated membrane and heats under vacuum, and the temperature of heating is 120-180 ℃, and the time of heating is 4-12 hour.
7. method according to claim 5, wherein, the weight ratio of described polyimides and pore-forming material is 100: 20-60, the weight ratio of described polyimides and solvent is 8-15: 100, described polyimides and polyolefinic weight ratio are 100: 5-50.
8. method according to claim 5, wherein, described polyimides is the polyimides with following structural formula:
Wherein, R
1And R
2Identical or different, be selected from aliphat or aromatic hydrocarbyl, the value of n is 50～10000.
9. method according to claim 5, wherein, the fusing point of described polyimides is 400-700 ℃.
10. method according to claim 5, wherein, this method comprises polynary organic carboxyl acid or derivatives thereof, organic diamine, pore-forming material is contacted with solvent, obtain the solution of homogeneous, then with solution film forming, remove the pore-forming material then, described polynary organic carboxyl acid or derivatives thereof is quaternary organic carboxyl acid, the organic acyl chlorides of quaternary, quaternary organic acid esters or binary organic acid acid anhydride.
11. method according to claim 10, wherein, the mol ratio of described polynary organic carboxyl acid or derivatives thereof and organic diamine is 0.99-1.05: 1, the total amount of described polynary organic carboxyl acid or derivatives thereof and organic diamine and the weight ratio of pore-forming material are 100: 20-60, the weight ratio of described solvent and polynary organic carboxyl acid or derivatives thereof and organic diamine polyimides is 100: 8-15.
12. according to claim 5 or 11 described methods, wherein, described solvent is selected from N-2-methyl pyrrolidone, N, N-dimethylacetylamide, N, one or more in dinethylformamide, dimethyl sulfoxide (DMSO), m-cresol, oxolane, the methyl alcohol.
13. method according to claim 10, wherein, the temperature that polynary organic carboxyl acid or derivatives thereof, organic diamine, pore-forming material are contacted with solvent is 0-90 ℃, and the time of contact is 4-24 hour.
14. method according to claim 10, wherein, this method will heat 1-5 hour down at 270-350 ℃ except that the film after desolvating before also being included in and removing the pore-forming material.
15. method according to claim 5, wherein, described pore-forming material is an inorganic crystal whisker, inorganic crystal whisker is selected from one or more in calcium sulfate crystal whiskers, potassium titanate crystal whisker, aluminium borate whisker, magnesium borate crystal whisker, alkali magnesium sulfate crystal whisker, magnesium hydroxide crystal whisker, Kocide SD whisker, silica whisker, alumina whisker, magnesia crystal whisker and the ZnOw, the pore-forming material is removed in the mode that adds solvent, described solvent is selected from one or more in the acid solution of water and/or organic solvent, or in the alkaline solution of water and/or organic solvent one or more.
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| CN101638490B (en) * | 2008-07-31 | 2012-09-12 | 比亚迪股份有限公司 | Polyimide porous membrane and preparation method and lithium ion battery thereof |
| CN101456967B (en) * | 2009-01-05 | 2011-10-12 | 中国工程物理研究院化工材料研究所 | Method for preparing thermoplastic polyimide porous material |
| US20110143217A1 (en) * | 2009-12-15 | 2011-06-16 | E. I. Du Pont De Nemours And Company | Electrochemical cell comprising a separator comprising a nanoweb consisting essentially of nanofibers of fully aromatic polyimide |
| JP2011243558A (en) * | 2010-04-22 | 2011-12-01 | Hitachi Maxell Energy Ltd | Lithium secondary battery positive electrode and lithium secondary battery |
| TWI524581B (en) | 2011-04-08 | 2016-03-01 | Teijin Ltd | Non-aqueous secondary battery separator and non-aqueous secondary battery |
| WO2012156903A1 (en) * | 2011-05-19 | 2012-11-22 | Basf Se | Electrochemical cells comprising polyimides |
| JP5922665B2 (en) * | 2011-09-29 | 2016-05-24 | 日立マクセル株式会社 | Lithium secondary battery |
| CN105489819A (en) * | 2016-02-01 | 2016-04-13 | 华东理工大学 | Lithium ion battery ceramic diaphragm paste |
| CN108303442B (en) * | 2017-12-18 | 2020-08-14 | 合肥国轩高科动力能源有限公司 | Diaphragm closed pore temperature testing method |
| CN108172743A (en) * | 2017-12-27 | 2018-06-15 | 桂林电器科学研究院有限公司 | Polyimides lithium battery diaphragm and preparation method thereof |
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| CN110635090B (en) * | 2019-09-27 | 2022-04-29 | 宁德卓高新材料科技有限公司 | Preparation method of high-heat-resistance vinylidene fluoride polymer mixed coating diaphragm |
| CN112952284B (en) * | 2019-12-11 | 2023-05-02 | 惠州比亚迪电池有限公司 | Lithium ion battery diaphragm, preparation method thereof and lithium ion battery |
| CN112838330B (en) * | 2021-01-08 | 2022-02-18 | 厦门大学 | High-temperature-resistant modified diaphragm and preparation method thereof |
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