CN105449140A - Separator and lithium ion secondary battery - Google Patents
Separator and lithium ion secondary battery Download PDFInfo
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- CN105449140A CN105449140A CN201410429341.0A CN201410429341A CN105449140A CN 105449140 A CN105449140 A CN 105449140A CN 201410429341 A CN201410429341 A CN 201410429341A CN 105449140 A CN105449140 A CN 105449140A
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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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E60/10—Energy storage using batteries
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Abstract
The invention provides a separation film and a lithium ion secondary battery. The ratio of the elongation at break in the Transverse Direction (TD) of the separator to the mechanical strength in the Transverse Direction (TD) of the separator is 1-60; the elongation at break in the Transverse Direction (TD) of the isolating film is 150-900%; the separator had a mechanical strength of 10kgf/cm in the Transverse Direction (TD)2～500kgf/cm2. The lithium ion secondary battery includes: a positive plate; a negative plate; the isolating film is spaced between the positive plate and the negative plate; and an electrolyte. The invention can effectively improve the passing rate of the lithium ion secondary battery after being abused by impact, nail penetration, side extrusion and the like, further improve the safety performance of the lithium ion secondary battery, and is particularly suitable for high-capacity batteries and high-energy-density batteries.
Description
Technical field
The present invention relates to cell art, particularly relate to a kind of barrier film and lithium rechargeable battery.
Background technology
Lithium rechargeable battery is since commercialization, due to its have that energy density is high, operating voltage is high, memory-less effect, have extended cycle life, the plurality of advantages such as environmentally safe and be widely used as the power supply of various mobile device, thus enter rapidly the large-scale practical stage.
Along with various portable electric appts multifunction and become more meticulous, the energy density of lithium rechargeable battery is had higher requirement, and the raising of the energy density of lithium rechargeable battery is had higher requirement to its security performance.When lithium rechargeable battery is in use subject to the abuse such as shock, drift bolt, side extruding, positive plate and negative plate can be short-circuited thus a large amount of heat release, when thermal accumlation to a certain extent after, just there is the risk of combustion explosion in lithium rechargeable battery.
In view of this, necessaryly a kind of lithium rechargeable battery with Good Security is provided.
Summary of the invention
In view of Problems existing in background technology, the object of the present invention is to provide a kind of barrier film and lithium rechargeable battery, its can effectively improve lithium rechargeable battery be subject to the abuse such as shock, drift bolt, side extruding after percent of pass, and then increase the security performance of lithium rechargeable battery, and be particularly useful in high-capacity battery and high energy density cells.
To achieve these goals, in a first aspect of the present invention, the invention provides a kind of barrier film, the ratio of the fracture elongation of described barrier film horizontal direction (TD) and the mechanical strength of described barrier film horizontal direction (TD) is 1 ~ 60; The fracture elongation of described barrier film horizontal direction (TD) is 150% ~ 900%; The mechanical strength of described barrier film horizontal direction (TD) is 10kgf/cm
2~ 500kgf/cm
2.
In a second aspect of the present invention, the invention provides a kind of lithium rechargeable battery, it comprises: positive plate; Negative plate; Barrier film, is interval between positive plate and negative plate; And electrolyte.Wherein, described barrier film is barrier film according to a first aspect of the present invention.
Beneficial effect of the present invention is as follows:
1. the fracture elongation of barrier film horizontal direction (TD) of the present invention is high and mechanical strength is low, when being therefore subject to the abuses such as shock, drift bolt, side extruding when the lithium rechargeable battery applying described barrier film, barrier film of the present invention can extend expansion rapidly, therefore can prevent the fragility because of barrier film from tearing the direct contact of the positive/negative plate caused, and then be conducive to protecting lithium rechargeable battery;
2. because safeguard measure of the present invention does not relate to the positive plate of lithium rechargeable battery, negative plate and electrolyte; therefore can not produce large impact to the chemical property of lithium rechargeable battery, therefore technical scheme of the present invention is particularly useful in high-capacity battery and high energy density cells.
Embodiment
The following detailed description of barrier film according to the present invention and lithium rechargeable battery and embodiment, comparative example and test result.
First barrier film is according to a first aspect of the present invention described.
Barrier film according to a first aspect of the present invention, the ratio of the fracture elongation of described barrier film horizontal direction (TD) and the mechanical strength of described barrier film horizontal direction (TD) is 1 ~ 60; The fracture elongation of described barrier film horizontal direction (TD) is 150% ~ 900%; The mechanical strength of described barrier film horizontal direction (TD) is 10kgf/cm
2~ 500kgf/cm
2.
In barrier film described according to a first aspect of the present invention, the calculating of the ratio of the fracture elongation of described barrier film horizontal direction (TD) and the mechanical strength of described barrier film horizontal direction (TD) only relates to the calculating of numerical value.For example, the fracture elongation of described barrier film horizontal direction (TD) is 200%, and the mechanical strength of described barrier film horizontal direction (TD) is 200kgf/cm
2, then the ratio of the fracture elongation of described barrier film horizontal direction (TD) and the mechanical strength of described barrier film horizontal direction (TD) is 1.
In barrier film described according to a first aspect of the present invention; the fracture elongation of described barrier film horizontal direction (TD) is high and mechanical strength is low; when being therefore subject to the abuses such as shock, drift bolt, side extruding when the lithium rechargeable battery applying described barrier film; barrier film of the present invention can extend expansion rapidly; therefore can prevent the fragility because of barrier film from tearing the direct contact of the positive/negative plate caused, and then be conducive to protecting lithium rechargeable battery.In addition; because safeguard measure of the present invention does not relate to the positive plate of lithium rechargeable battery, negative plate and electrolyte; therefore can not produce large impact to the chemical property of lithium rechargeable battery, therefore technical scheme of the present invention is particularly useful in high-capacity battery and high energy density cells.
In barrier film described according to a first aspect of the present invention, the described fracture elongation of barrier film horizontal direction (TD) and the ratio of mechanical strength can be 4 ~ 35; The fracture elongation of described barrier film horizontal direction (TD) can be 250% ~ 600%; The mechanical strength of described barrier film horizontal direction (TD) can be 10kgf/cm
2~ 200kgf/cm
2.Under the above parameters, fracture elongation and the mechanical strength of barrier film are more excellent, and it just can extend expansion rapidly under the effect being subject to less power.
In barrier film described according to a first aspect of the present invention, the ratio of the mechanical strength of described barrier film longitudinal direction (MD) and the fracture elongation of described barrier film longitudinal direction (MD) can be 1 ~ 18; The fracture elongation of described barrier film longitudinal direction (MD) can be 55% ~ 600%; The mechanical strength of described barrier film longitudinal direction (MD) can be 600kgf/cm
2~ 3000kgf/cm
2.
In barrier film described according to a first aspect of the present invention, preferably, the ratio of the mechanical strength of described barrier film longitudinal direction (MD) and the fracture elongation of described barrier film longitudinal direction (MD) can be 1.6 ~ 8; The fracture elongation of described barrier film longitudinal direction (MD) can be 200% ~ 500%; The mechanical strength of described barrier film longitudinal direction (MD) can be 800kgf/cm
2~ 2000kgf/cm
2.
In barrier film described according to a first aspect of the present invention, the calculating of the ratio of the mechanical strength of described barrier film longitudinal direction (MD) and the fracture elongation of described barrier film longitudinal direction (MD) only relates to the calculating of numerical value.For example, the fracture elongation of described barrier film longitudinal direction (MD) is 500%, and the mechanical strength of described barrier film longitudinal direction (MD) is 800kgf/cm
2, then the ratio of the mechanical strength of described barrier film longitudinal direction (MD) and the fracture elongation of described barrier film longitudinal direction (MD) is 1.6.
In barrier film described according to a first aspect of the present invention, the optional at least one in polyolefin, polyimides, polyurethane, PIC of described barrier film.
In barrier film described according to a first aspect of the present invention, the optional at least one in polypropylene (PP), polyethylene (PE) of described polyolefin.
In barrier film described according to a first aspect of the present invention, described barrier film also can comprise flexibilizer.
In barrier film described according to a first aspect of the present invention, described flexibilizer can be selected from ethylene-propylene rubber.
In barrier film described according to a first aspect of the present invention, the surface of described barrier film can be coated with inorganic particulate coatings and/or organic granular coating, has stronger thermal endurance and puncture resistance to make barrier film.
In barrier film described according to a first aspect of the present invention, at least one in the optional self-alumina of the inorganic particle in described inorganic particulate coatings, silicon dioxide, titanium dioxide, ceria, calcium carbonate, calcium oxide, zinc oxide, magnesium oxide, Cerium titanate, calcium titanate, barium titanate, lithium phosphate, titanium phosphate lithium, titanium phosphate aluminium lithium, lithium nitride, lanthanium titanate lithium; The optional at least one in Kynoar, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyimides, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, acrylic-styrene copolymer, dimethyl silicone polymer, Sodium Polyacrylate, sodium carboxymethylcellulose of organic granular in described organic granular coating.
Secondly lithium rechargeable battery is according to a second aspect of the present invention described.
Lithium rechargeable battery according to a second aspect of the present invention, comprising: positive plate; Negative plate; Barrier film, is interval between positive plate and negative plate; And electrolyte.Wherein, described barrier film is barrier film according to a first aspect of the present invention.
Following explanation is according to the embodiment of barrier film of the present invention and lithium rechargeable battery and comparative example.
Embodiment 1
1. the preparation of the negative plate of lithium rechargeable battery
Solvent deionized water and thickener sodium carboxymethylcellulose (CMC) are joined in mixer grinder, makes it dissolve under vacuum conditions completely, obtain aqueous high molecular solution; Joined by conductive agent conductive black in the aqueous high molecular solution dissolved, it is less than 5 μm that rapid stirring is ground to fineness again; Add negative electrode active material Delanium more afterwards, and slowly stir under vacuum; Add binding agent butadiene-styrene latex more afterwards, and slowly stir at vacuum condition; Afterwards with 150 order stainless steel sift net filtrations i.e. obtained cathode size, wherein, the solids content of cathode size is 67%; Cathode size is uniformly coated on the two sides that thickness is the copper foil of affluxion body of 8 μm subsequently, after drying, obtains cathode membrane, then use roll squeezer compacting, last cut-parts, soldering polar ear, namely obtain the negative plate of lithium rechargeable battery.Wherein, the mass ratio of negative electrode active material, conductive agent, binding agent, thickener is 94.5:1.5:2:2.
2. the preparation of the positive plate of lithium rechargeable battery
Solvent N-methyl pyrilidone (NMP) and binding agent Kynoar (PVDF) are joined in mixer grinder, makes it dissolve under vacuum conditions completely, obtain oiliness PVDF solution; Joined by conductive agent conductive black in the oiliness PVDF solution dissolved, it is less than 5 μm that rapid stirring is ground to fineness again; Add positive active material cobalt acid lithium (LiCoO afterwards again
2), and stir under vacuum; Afterwards with 200 order stainless steel sift net filtrations i.e. obtained anode sizing agent, wherein, the solids content of anode sizing agent is 41%; Anode sizing agent is uniformly coated on the two sides that thickness is the current collector aluminum foil of 12 μm subsequently, then with roll squeezer by compacting, last cut-parts, soldering polar ear, namely obtain the positive plate of lithium rechargeable battery.Wherein, the mass ratio of positive active material, binding agent, conductive agent is 92:4:4.
3. the preparation of the electrolyte of lithium rechargeable battery
By ethylene carbonate (EC), propene carbonate (PC) and dimethyl carbonate (DMC) by volume 3:3:4 be mixed with non-aqueous organic solvent, then add lithium hexafluoro phosphate (LiPF
6) as lithium salts, and make LiPF
6concentration be 1M, obtain the electrolyte of lithium rechargeable battery after stirring.
4. the preparation of the barrier film of lithium rechargeable battery
(1) be the HOPP (PP) of 3.0g/10min by melt index, ethylene-propylene rubber, phthalic acid ester, talcum, tetrabromobutane add in batch mixer to stir and obtain mixture, wherein, mixing speed is 3000rpm, mixing time is 40min, and the quality of ethylene-propylene rubber is 3% of the quality of HOPP (PP);
(2) mixture of gained is joined in single screw extrusion machine, and at 215 DEG C, fusion plastification is even, obtains melt;
(3) extruded from die head by the melt of gained and obtain slab, enter curtain coating operation subsequently, obtain the intermediate membrane that thickness is 16 μm, wherein, die head temperature is 200 DEG C, and casting temperature is 65 DEG C;
(4) intermediate membrane of gained is put into constant temperature oven and carry out annealing in process, wherein, the temperature of baking oven is 140 DEG C, and annealing time is 11h;
(5) intermediate membrane after annealing is carried out longitudinally (MD) stretching of two steps, wherein, cold drawn temperature is 25 DEG C, and cold drawn multiplying power is 35%, hot-drawn temperature 140 DEG C, hot-drawn multiplying power 120%;
(6) carry out a step laterally (TD) stretching again to the barrier film after longitudinal stretching, wherein, hot-drawn temperature is 140 DEG C, and hot-drawn multiplying power is 100%;
(7) finally carry out thermal finalization to barrier film, complete the preparation of barrier film, heat setting temperature is 130 DEG C, and heat-setting time is 25s.
5. the preparation of lithium rechargeable battery
Above-mentioned positive plate, barrier film, negative plate are wound into battery core, then this battery core is placed in aluminium plastic packaging bag, inject above-mentioned electrolyte, through encapsulating, changing into, the operation such as capacity, obtain length and width, the thick rectangle flexible packing lithium ion secondary battery being respectively 135mm, 80mm, 3.2mm, wherein, the capacity of lithium rechargeable battery is 5000mAh, and voltage is 4.4V.
Embodiment 2
Method according to embodiment 1 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) ethylene-propylene rubber is not added;
(5) cold drawn multiplying power is 30%;
(6) hot-drawn temperature is 135 DEG C, and hot-drawn multiplying power is 80%.
Embodiment 3
Method according to embodiment 1 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(6) hot-drawn temperature is 130 DEG C, and hot-drawn multiplying power is 50%.
Embodiment 4
Method according to embodiment 1 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) be the high density polyethylene (HDPE) (PE) of 0.8g/10min by melt index, phthalic acid ester, talcum, tetrabromobutane add in batch mixer to stir and obtain mixture, and wherein, mixing speed is 3000rpm, and mixing time is 40min;
(2) mixture of gained is joined in single screw extrusion machine, and at 210 DEG C, fusion plastification is even, obtains melt;
(4) oven temperature is 120 DEG C, and annealing time is 9h;
(5) cold drawn multiplying power 25%, hot-drawn temperature 120 DEG C, hot-drawn multiplying power 125%;
(6) hot-drawn temperature is 110 DEG C, and hot-drawn multiplying power is 30%;
(7) heat setting temperature is 120 DEG C.
Embodiment 5
Method according to embodiment 4 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
Behind completing steps (1)-(7), be coated with one deck inorganic ceramic grain coating to the barrier film after thermal finalization, coating thickness is 4 μm.
Embodiment 6
Method according to embodiment 4 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) be the high density polyethylene (HDPE) (PE) of 0.8g/10min by melt index, ethylene-propylene rubber, phthalic acid ester, talcum, tetrabromobutane add in batch mixer to stir and obtain mixture, wherein, mixing speed is 3000rpm, mixing time is 40min, and the quality of ethylene-propylene rubber is 5% of the quality of high density polyethylene (HDPE) (PE);
(4) annealing time is 11h;
(5) cold drawn multiplying power 35%;
(6) again cross directional stretch is not carried out to the barrier film after longitudinal stretching, namely do not perform step (6).
Embodiment 7
Method according to embodiment 6 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(5) hot-drawn multiplying power 130%.
Embodiment 8
Method according to embodiment 6 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) quality of ethylene-propylene rubber is 7% of the quality of high density polyethylene (HDPE) (PE);
(4) annealing time is 9h;
(5) hot-drawn multiplying power 130%.
Embodiment 9
Method according to embodiment 8 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(5) cold drawn multiplying power is 30%, and hot-drawn multiplying power is 140%.
Embodiment 10
Method according to embodiment 9 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(6) hot-drawn temperature is 120 DEG C, and hot-drawn multiplying power is 95%.
Embodiment 11
Method according to embodiment 10 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) quality of ethylene-propylene rubber is 10% of the quality of high density polyethylene (HDPE) (PE);
(4) annealing time is 8h;
(5) cold drawn multiplying power is 20%, and hot-drawn multiplying power is 145%;
(6) hot-drawn multiplying power be 100%.
Embodiment 12
Method according to embodiment 10 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(4) annealing time is 11h;
(5) cold drawn multiplying power is 20%, and hot-drawn multiplying power is 110%;
(6) hot-drawn temperature is 110 DEG C, and hot-drawn multiplying power is 30%.
Embodiment 13
Method according to embodiment 12 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(6) hot-drawn temperature is 120 DEG C, and hot-drawn multiplying power is 100%.
Embodiment 14
Method according to embodiment 12 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(4) annealing time is 9h;
(5) hot-drawn temperature is 110 DEG C.
Embodiment 15
Method according to embodiment 14 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) quality of ethylene-propylene rubber is 10% of the quality of high density polyethylene (HDPE) (PE);
(5) hot-drawn multiplying power be 85%.
Embodiment 16
Method according to embodiment 12 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(4) annealing time is 12h;
(5) hot-drawn multiplying power be 130%;
(6) hot-drawn temperature is 120 DEG C, and hot-drawn multiplying power is 100%.
Embodiment 17
Method according to embodiment 16 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) quality of ethylene-propylene rubber is 10% of the quality of high density polyethylene (HDPE) (PE);
(5) hot-drawn multiplying power be 155%.
Comparative example 1
Method according to embodiment 1 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(1) ethylene-propylene rubber is not added;
(4) annealing time is 12h;
(5) cold drawn multiplying power is 45%;
(6) hot-drawn multiplying power be 140%.
Comparative example 2
Method according to embodiment 4 prepares lithium rechargeable battery, except following difference:
4. the preparation of the barrier film of lithium rechargeable battery
(4) annealing time is 12h;
(5) cold drawn multiplying power is 45%, and hot-drawn multiplying power is 115%;
(6) hot-drawn temperature is 120 DEG C, and hot-drawn multiplying power is 140%.
Following explanation is according to the test process of barrier film of the present invention and lithium rechargeable battery and test result.
(1) fracture elongation of barrier film and mechanical strength test
Tensile test is carried out to the barrier film of comparative example 1-2 and embodiment 1-17, often organize and get 20 barrier films, wherein test fracture elongation and the mechanical strength of barrier film horizontal direction (TD) for 10, the fracture elongation of other 10 tests barrier film longitudinal direction (MD) and mechanical strength.Test process is as follows: first by barrier film, transversely direction (TD) is cut into the wide 14.5mm of being, length is the sample of 50mm, adopt high ferro puller system with the constant rate of speed stretching barrier film of 50mm/min, tensile elongation when record barrier film horizontal direction (TD) ruptures and mechanical strength, can obtain fracture elongation and the mechanical strength of barrier film horizontal direction (TD); By barrier film, (MD) is cut into the wide 14.5mm of being along the longitudinal direction, length is the sample of 50mm afterwards, adopt high ferro puller system with the constant rate of speed stretching barrier film of 50mm/min, tensile elongation when record barrier film longitudinal direction (MD) ruptures and mechanical strength, can obtain fracture elongation and the mechanical strength of barrier film longitudinal direction (MD).
(2) impact test of lithium rechargeable battery
At 25 DEG C, with 0.5C multiplying power constant current charge to 4.4V, constant voltage charge is to 0.05C afterwards.Adopt UL1642 testing standard, weight quality is 9.8kg, iron staff diameter is 15.8mm, height of drop is 61 ± 2.5cm, impact test is carried out to the lithium rechargeable battery of comparative example 1-2 and embodiment 1-17, often organize test 100 lithium rechargeable batteries, calculate the percent of pass of the impact test of lithium rechargeable battery.
(3) the drift bolt test of lithium rechargeable battery
At 25 DEG C, with 0.5C multiplying power constant current charge to 4.4V, constant voltage charge is to 0.05C afterwards.Carry out drift bolt test to the lithium rechargeable battery of comparative example 1-2 and embodiment 1-17, wherein, drift bolt speed is 100mm/s, thickness 2.5mm, often organizes test 100 lithium rechargeable batteries, calculates the percent of pass of the drift bolt test of lithium rechargeable battery.
(4) the side extruding test of lithium rechargeable battery
At 25 DEG C, with 0.5C multiplying power constant current charge to 4.4V, constant voltage charge is to 0.05C afterwards.Adopt UL1642 testing standard, side extruding force is 13kN.Side extruding test is carried out to the lithium rechargeable battery of comparative example 1-2 and embodiment 1-17, often organizes test 100 lithium rechargeable batteries, calculate the percent of pass of the side extruding test of lithium rechargeable battery.
Table 1 provides parameter and the performance test results of embodiment 1-17 and comparative example 1-2.
As can be seen from Table 1, the ratio of the fracture elongation of the barrier film horizontal direction (TD) of embodiments of the invention 1-17 and the mechanical strength of barrier film horizontal direction (TD) is far above comparative example 1-2, and then the percent of pass of lithium rechargeable battery impact test is all higher.This is because the fracture elongation of barrier film horizontal direction (TD) of the present invention is high and mechanical strength is low; therefore when lithium rechargeable battery is subject to clashing into; barrier film of the present invention can extend expansion rapidly; therefore can prevent the fragility because of barrier film from tearing the direct contact of the positive/negative plate caused, and then be conducive to protecting lithium rechargeable battery.And increase along with the ratio of the fracture elongation of barrier film horizontal direction (TD) and the mechanical strength of barrier film horizontal direction (TD), the percent of pass of lithium rechargeable battery impact test increases.And the present invention adds flexibilizer ethylene-propylene rubber in the preparation process of barrier film, it can increase the ductility of barrier film to a certain extent, and then increases the percent of pass of lithium rechargeable battery impact test.
When the ratio of the mechanical strength of barrier film longitudinal direction (MD) and the fracture elongation of barrier film longitudinal direction (MD) is lower (with reference to embodiment 12-16); now; when lithium rechargeable battery is subject to side extruding; the ductility of barrier film longitudinal direction (MD) excellence can make it extend expansion rapidly; therefore can prevent the fragility because of barrier film from tearing the direct contact of the positive/negative plate caused, and then be conducive to protecting lithium rechargeable battery.
When the ratio of the fracture elongation of barrier film horizontal direction (TD) and the mechanical strength of barrier film horizontal direction (TD) is too high, correspondingly, the mechanical strength of barrier film horizontal direction (TD) is lower (with reference to embodiment 6-9), therefore the puncture-resistant ability of barrier film can reduce, and is unfavorable for that lithium rechargeable battery is tested by drift bolt.But when barrier film horizontal direction (TD) and longitudinal direction (MD) have high fracture elongation simultaneously (with reference to embodiment 12, embodiment 14, embodiment 15), namely the ratio of the fracture elongation of barrier film horizontal direction (TD) and the mechanical strength of barrier film horizontal direction (TD) is higher, the ratio of the mechanical strength of barrier film longitudinal direction (MD) and the fracture elongation of barrier film longitudinal direction (MD) is lower simultaneously, now, when being subject to the needle-like foreign matter impacts such as nail when lithium rechargeable battery, the ductility of barrier film longitudinal direction (MD) and horizontal direction (TD) excellence can stop the needle-like foreign matters such as nail to puncture barrier film, and barrier film also can wrap the tip of nail, prevent its contact positive/negative plate, and then be conducive to protecting lithium rechargeable battery.When barrier film horizontal direction (TD) and longitudinal direction (MD) have high fracture elongation simultaneously (with reference to embodiment 12, embodiment 14, embodiment 15), namely the ratio of the fracture elongation of barrier film horizontal direction (TD) and the mechanical strength of barrier film horizontal direction (TD) is higher, when the ratio of the mechanical strength of barrier film longitudinal direction (MD) and the fracture elongation of barrier film longitudinal direction (MD) is lower simultaneously, the percent of pass of lithium rechargeable battery impact test and side extruding test all can improve.
It can also be seen that from the contrast of embodiment 4 and embodiment 5, embodiment 5 is coated with one deck inorganic ceramic grain coating on the surface of barrier film, can increase thermal endurance and the paracentesis resistance of barrier film, and the percent of pass of therefore lithium rechargeable battery drift bolt test increases.
In sum, when the ratio of the fracture elongation of barrier film horizontal direction (TD) of the present invention and the mechanical strength of barrier film horizontal direction (TD) is higher, is conducive to lithium rechargeable battery and passes through impact test.When the ratio of the mechanical strength of barrier film longitudinal direction (MD) of the present invention and the fracture elongation of barrier film longitudinal direction (MD) is lower, be conducive to lithium rechargeable battery by side extruding test.In addition, if the ratio of the fracture elongation of barrier film horizontal direction (TD) of the present invention and the mechanical strength of barrier film horizontal direction (TD) is higher, the ratio of the mechanical strength of barrier film longitudinal direction (MD) and the fracture elongation of barrier film longitudinal direction (MD) is also lower simultaneously, and the percent of pass of the test of lithium rechargeable battery impact test, drift bolt and side extruding test is all higher.
Claims (10)
1. a barrier film, is characterized in that,
The ratio of the fracture elongation of described barrier film horizontal direction (TD) and the mechanical strength of described barrier film horizontal direction (TD) is 1 ~ 60;
The fracture elongation of described barrier film horizontal direction (TD) is 150% ~ 900%;
The mechanical strength of described barrier film horizontal direction (TD) is 10kgf/cm
2~ 500kgf/cm
2.
2. barrier film according to claim 1, is characterized in that,
The ratio of the fracture elongation of described barrier film horizontal direction (TD) and the mechanical strength of described barrier film horizontal direction (TD) is 4 ~ 35;
The fracture elongation of described barrier film horizontal direction (TD) is 250% ~ 600%;
The mechanical strength of described barrier film horizontal direction (TD) is 10kgf/cm
2~ 200kgf/cm
2.
3. barrier film according to claim 1, is characterized in that,
The ratio of the mechanical strength of described barrier film longitudinal direction (MD) and the fracture elongation of described barrier film longitudinal direction (MD) is 1 ~ 18;
The fracture elongation of described barrier film longitudinal direction (MD) is 55 ~ 600%;
The mechanical strength of described barrier film longitudinal direction (MD) is 600kgf/cm
2~ 3000kgf/cm
2.
4. barrier film according to claim 3, is characterized in that,
The mechanical strength of described barrier film longitudinal direction (MD) and the fracture elongation of described barrier film longitudinal direction (MD) ratio be 1.6 ~ 8;
The fracture elongation of described barrier film longitudinal direction (MD) is 200% ~ 500%;
The mechanical strength of described barrier film longitudinal direction (MD) is 800kgf/cm
2~ 2000kgf/cm
2.
5. barrier film according to claim 1, is characterized in that, described barrier film is selected from least one in polyolefin, polyimides, polyurethane, PIC.
6. barrier film according to claim 5, is characterized in that, described polyolefin is selected from least one in polypropylene (PP), polyethylene (PE).
7. barrier film according to claim 1, is characterized in that, described barrier film also comprises flexibilizer.
8. barrier film according to claim 1, is characterized in that, the surface of described barrier film is coated with inorganic particulate coatings and/or organic granular coating.
9. barrier film according to claim 8, is characterized in that,
Inorganic particle in described inorganic particulate coatings is selected from least one in aluminium oxide, silicon dioxide, titanium dioxide, ceria, calcium carbonate, calcium oxide, zinc oxide, magnesium oxide, Cerium titanate, calcium titanate, barium titanate, lithium phosphate, titanium phosphate lithium, titanium phosphate aluminium lithium, lithium nitride, lanthanium titanate lithium;
Organic granular in described organic granular coating is selected from least one in Kynoar, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyimides, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, acrylic-styrene copolymer, dimethyl silicone polymer, Sodium Polyacrylate, sodium carboxymethylcellulose.
10. a lithium rechargeable battery, comprising:
Positive plate;
Negative plate;
Barrier film, is interval between positive plate and negative plate; And
Electrolyte;
It is characterized in that,
Described barrier film is the barrier film according to any one of claim 1-9.
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| CN201410429341.0A CN105449140A (en) | 2014-08-27 | 2014-08-27 | Separator and lithium ion secondary battery |
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| CN201410429341.0A CN105449140A (en) | 2014-08-27 | 2014-08-27 | Separator and lithium ion secondary battery |
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| CN105449140A true CN105449140A (en) | 2016-03-30 |
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| CN201410429341.0A Pending CN105449140A (en) | 2014-08-27 | 2014-08-27 | Separator and lithium ion secondary battery |
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