CN102986060B - Separator for lithium ion secondary battery and use its lithium rechargeable battery - Google Patents

Separator for lithium ion secondary battery and use its lithium rechargeable battery Download PDF

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Publication number
CN102986060B
CN102986060B CN201180034584.9A CN201180034584A CN102986060B CN 102986060 B CN102986060 B CN 102986060B CN 201180034584 A CN201180034584 A CN 201180034584A CN 102986060 B CN102986060 B CN 102986060B
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separator
ion secondary
secondary battery
lithium ion
fiber
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CN102986060A (en
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松冈昌伸
佐藤友洋
加藤加寿美
笠井誉子
绿川正敏
松田伯志
锻冶裕夫
山本浩和
渡边宏明
佃贵裕
藤田郁夫
兵头建二
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Mitsubishi Paper Mills Ltd
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Mitsubishi Paper Mills Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/429—Natural polymers
    • H01M50/4295—Natural cotton, cellulose or wood
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/429—Natural polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Cell Separators (AREA)
  • Artificial Filaments (AREA)
  • Multicomponent Fibers (AREA)
  • Paper (AREA)

Abstract

The invention provides moisture content low, mechanical strength is strong, internal resistance, internal short-circuit fraction defective, flash-over characteristic particularly under high magnification and deviation thereof, the separator for lithium ion secondary battery of cycle characteristics excellence and use the lithium rechargeable battery of described dividing plate, described separator for lithium ion secondary battery is the solvent-spun cellulose fibre of 0 ~ 250ml by the political reform freedom containing 10 ~ 90 quality %, the Porous sheet material of the synthetic fibers of 10 ~ 90 quality % is formed, described political reform freedom is except using wire diameter to be 0.14mm, aperture is that the 80 order wire nettings of 0.18mm are as sieve plate, sample solution concentration is set to beyond 0.1%, according to JIS? P8121 measures.

Description

Separator for lithium ion secondary battery and use its lithium rechargeable battery
Technical field
The present invention relates to separator for lithium ion secondary battery and use its lithium rechargeable battery.
Background technology
Along with the universal of portable electronic piece machinery in recent years and high performance thereof, expect the secondary cell with high-energy-density.As this battery, the lithium rechargeable battery of organic electrolyte (nonaqueous electrolytic solution) is used to receive publicity.The average voltage of this lithium rechargeable battery is the 3.7V of about 3 times of alkaline secondary cell, reaches high-energy-density, but due to aqueous electrolyte cannot be used as alkaline secondary cell, so use the nonaqueous electrolytic solution with sufficient oxidation-reduction resistance.
As separator for lithium ion secondary battery, the porous film (such as with reference to patent documentation 1) of the film-form using polyolefin to be formed more, but due to guarantor's fluidity of electrolyte low, reduce so there is ionic conductivity, the problem that internal resistance raises.
In addition, as separator for lithium ion secondary battery, propose based on the dividing plate made of paper of the making beating of regenerated celulose fibre (beating) thing (such as with reference to patent documentation 2).In lithium rechargeable battery, even if be mixed into few moisture, also can cause harmful effect to battery behavior, so when dividing plate made of paper high for moisture content is used for dividing plate, the needs dry process for a long time when preparing lithium rechargeable battery.In addition, because diaphragm strength is weak, so there is the problem that dividing plate cannot be made thinning.
In addition, as separator for lithium ion secondary battery, it is also proposed the nonwoven fabrics dividing plate (such as with reference to patent documentation 3 ~ 5) that synthetic fibers are formed, but guarantor's fluidity that these dividing plates exist electrolyte reduces, the problem that internal resistance raises, or due to the compactness of dividing plate not enough, raise so there is internal short-circuit fraction defective, the problem of high-rate characteristics or flash-over characteristic and deviation difference thereof.
In addition, as separator for lithium ion secondary battery, propose the dividing plate (such as with reference to patent documentation 6 ~ 8) formed by fibrillation heat resistant fibre, fibrillating fibre element, nonfibrillated fiber, in this dividing plate, diaphragm strength still has room for improvement.
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 2002-105235 publication
Patent documentation 2: Japanese Patent No. 3661104 publications
Patent documentation 3: Japanese Unexamined Patent Publication 2003-123728 publication
Patent documentation 4: Japanese Unexamined Patent Publication 2007-317675 publication
Patent documentation 5: Japanese Unexamined Patent Publication 2006-19191 publication
Patent documentation 6: International Publication No. 2005/101432 pamphlet
Patent documentation 7: International Publication No. 1996/030954 pamphlet
Patent documentation 8: Japanese Unexamined Patent Publication 2004-146137 publication.
Summary of the invention
Invent problem to be solved
The present invention is in view of above-mentioned actual conditions, there is provided moisture content low, mechanical strength is strong, the separator for lithium ion secondary battery of the flash-over characteristic under internal resistance, internal short-circuit fraction defective, particularly high magnification and deviation thereof, cycle characteristics excellence, and uses the lithium rechargeable battery of this dividing plate.
Solve the means of problem
Furtheing investigate for solving above-mentioned problem, found that following separator for lithium ion secondary battery and lithium rechargeable battery.
(1) separator for lithium ion secondary battery, described separator for lithium ion secondary battery by be the solvent-spun cellulose fibre of 0 ~ 250ml containing the political reform freedom of 10 ~ 90 quality %, the Porous sheet material of the synthetic fibers of 10 ~ 90 quality % formed, described political reform freedom except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm are as sieve plate, sample solution concentration is set to beyond 0.1%, measures according to JISP8121.
(2) separator for lithium ion secondary battery recorded in (1), wherein, the length weighted average fiber length of solvent-spun cellulose fibre is 0.20 ~ 2.00mm.
(3) separator for lithium ion secondary battery recorded in (1) or (2), wherein, solvent-spun cellulose fibre has peak frequency peak in its length weighted fibre distribution of lengths histogram between 0.00 ~ 1.00mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 10%.
(4) separator for lithium ion secondary battery recorded in (3), wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, the slope with the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm is for more than-3.0 and below-0.5.
(5) separator for lithium ion secondary battery recorded in (1) or (2), wherein, solvent-spun cellulose fibre has peak frequency peak in its length weighted fibre distribution of lengths histogram between 0.00 ~ 1.00mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 50%.
(6) separator for lithium ion secondary battery recorded in (5), wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, except peak frequency peak, has peak between 1.50 ~ 3.50mm.
(7) separator for lithium ion secondary battery recorded in (1) or (2), wherein, the length weighted average fiber length of solvent-spun cellulose fibre is 0.50 ~ 1.25mm, and Average curl degree is less than 25.
(8) separator for lithium ion secondary battery recorded in any one of (1) ~ (7), wherein, the political reform freedom of Porous sheet material further containing below 20 quality % is that the fibrillation native cellulose fibre of 0 ~ 400ml forms, described political reform freedom except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm are as sieve plate, sample solution concentration is set to beyond 0.1%, measures according to JISP8121.
(9) separator for lithium ion secondary battery recorded in (1), wherein, Porous sheet material forms containing carboxymethyl cellulose further.
(10) separator for lithium ion secondary battery recorded in (1), wherein, Porous sheet material contains the core-sheath-type heat fusing adhesion fiber be made up of heat fusing adhesion composition and non-heat fusing adhesion composition and forms as at least 1 in synthetic fibers kind.
(11) separator for lithium ion secondary battery recorded in (10), wherein, the core of core-sheath-type heat fusing adhesion fiber is PETG, and sheath portion is polyester copolymer.
(12) separator for lithium ion secondary battery recorded in (10) or (11), wherein, Porous sheet material forms through heat treatment.
(13) separator for lithium ion secondary battery recorded in any one of (1) ~ (12), wherein, the average pore size of Porous sheet material is more than 0.10 μm, and maximum diameter of hole is less than 6.0 μm.
(14) separator for lithium ion secondary battery recorded in any one of (1) ~ (12), wherein, in Porous sheet material, the value that measures according to the method that specifies in JISB7502 (thickness of the sheet material measured by outside micrometer when load is 5N) is 6 ~ 50 μm.
(15) separator for lithium ion secondary battery recorded in any one of (1) ~ (12), wherein, the basic weight of Porous sheet material is 5 ~ 40g/m 2.
(16) separator for lithium ion secondary battery recorded in any one of (1) ~ (15), wherein, the synthetic resin forming synthetic fibers is be selected from least a kind in polyester resin, acrylic resin, polyolefin resin.
(17) separator for lithium ion secondary battery recorded in any one of (1) ~ (16), wherein, the fiber diameter of synthetic fibers is 0.1 ~ 20 μm.
(18) separator for lithium ion secondary battery recorded in (1), wherein, Porous sheet material comprises sandwich construction, and more than at least two layers is contain the layer of solvent-spun cellulose fibre as required composition that political reform freedom is 0 ~ 250ml.
(19) lithium rechargeable battery, described lithium rechargeable battery uses the separator for lithium ion secondary battery recorded in any one of (1) ~ (18) to form.
The effect of invention
Separator for lithium ion secondary battery of the present invention is by containing political reform freedom (Bian Fa Filter water degree) formed into the solvent-spun cellulose fibre of 0 ~ 250ml and the nonwoven fabrics of synthetic fibers.Be that the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers are wound around mutually by political reform freedom, guarantor's fluidity of the electrolyte of separator for lithium ion secondary battery can be made good, thus can internal resistance be reduced, particularly can be made into the article of the flash-over characteristic excellence under high magnification.In addition, due to separator for lithium ion secondary battery can be made fine and close, so the deviation of internal short-circuit fraction defective, flash-over characteristic can be suppressed.In addition, by containing synthetic fibers, the moisture content of dividing plate can be suppressed to be low-level, dry processing time time prepared by battery can be shortened further.
In addition, between synthetic fibers and political reform freedom be that the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers are easy to be wound around, by forming network of fibers, diaphragm strength can be strengthened, dividing plate can be made finer and close and thin, while can reducing internal resistance, the deviation of internal short-circuit fraction defective, flash-over characteristic can be suppressed, cycle characteristics can be made excellent.
Accompanying drawing explanation
The length weighted fibre distribution of lengths histogram of [Fig. 1] solvent-spun cellulose fibre [I].
The length weighted fibre distribution of lengths histogram of [Fig. 2] solvent-spun cellulose fibre [II].
[Fig. 3] illustrates in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre [I] and [II], has the curve of ratio and the figure of near linear of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm.
The length weighted fibre distribution of lengths histogram of [Fig. 4] solvent-spun cellulose fibre [i].
The length weighted fibre distribution of lengths histogram of [Fig. 5] solvent-spun cellulose fibre [ii].
Embodiment
Below the lithium rechargeable battery of separator for lithium ion secondary battery of the present invention (also having the situation being labeled as " dividing plate " below) and this dividing plate of use is described in detail.
Solvent-spun cellulose fibre in the present invention, with as viscose rayon yarn in the past or copper rayon, cellulosic so-called regenerated celulose fibre is again reverted to different after making cellulose temporarily be chemically converted to cellulose derivative, refer to and do not make cellulose generation chemical change and the spinning solution being dissolved in amine oxide carried out in water dry-wet spinning, separate out cellulose and the fiber that obtains, also referred to as " lyocell (Lyocell) fiber ".Compared with solvent-spun cellulose fibre and native cellulose fibre or bacteria cellulose fibre, rayon fiber, due to numberator height ground ordered arrangement on fiber long axes direction, if so apply the mechanical forces such as friction under moisture state, then easy granular, generates thin, long microfibre.Owing to keeping electrolyte securely between this microfibre, so compared with the trickle compound of native cellulose fibre, bacteria cellulose fibre, rayon fiber, the solvent-spun cellulose fibre of granular is excellent in guarantor's fluidity of electrolyte.
In the present invention, political reform freedom is used to be the solvent-spun cellulose fibre of 0 ~ 250ml.The political reform freedom of solvent-spun cellulose fibre is more preferably 0 ~ 200ml, more preferably 0 ~ 160ml.If political reform freedom is higher than 250ml, then the compactness of dividing plate becomes insufficient, and internal short-circuit fraction defective raises.
Political reform freedom in the present invention be except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm as sieve plate, sample solution concentration is set to beyond 0.1%, according to the value that JISP8121 measures.
When solvent-spun cellulose fibre, along with the carrying out of granular, fibre length shortens, if particularly sample solution concentration is rare, then interfibrous winding tails off, thus is difficult to form network of fibers, so solvent-spun cellulose fibre is itself by the hole of sieve plate.In other words, when the solvent-spun cellulose of granular, the assay method by means of JISP8121 cannot measure correct freedom.If illustrate in greater detail, then native cellulose fibre is in progress due to the degree of granular, more be in the state of tiny fibrillation from the dry Mass Cracking of fiber, so be easily wound around via fibrillation between fiber, easy formation network of fibers, on the other sidely be, solvent-spun cellulose fibre is easily parallel to fiber major axis by granular process is split subtly, because the homogeneity by the fibre diameter of root fiber after segmentation is high, so average fiber length becomes shorter, just become between fiber and be more difficult to be wound around, think and be difficult to form network of fibers.Therefore, in the present invention, being measure the correct freedom of solvent-spun cellulose fibre, adopting except using wire diameter is 0.14mm, aperture is 0.18mm 80 order wire nettings as sieve plate, sample solution concentration is set to beyond 0.1%, according to the political reform freedom that JISP8121 measures.
In addition, political reform freedom is that the length weighted average fiber length of the solvent-spun cellulose fibre of 0 ~ 250ml is preferably 0.20 ~ 3.00mm, is more preferably 0.20 ~ 2.00mm, more preferably 0.20 ~ 1.60mm.If length weighted average fiber is shorter in length than 0.20mm, then there is situation about coming off from dividing plate, if be longer than 3.00mm, then fiber likely tangles agglomerating, there is the situation producing uneven thickness.
Fig. 1 and Fig. 2 is the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre.As Fig. 1 and Fig. 2, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, there is peak frequency peak between 0.00 ~ 1.00mm, the ratio with the fiber of more than 1.00mm length weighted fibre length is that the separator for lithium ion secondary battery (3) of more than 10% is owing to being easily wound around between fiber, thus easily form network of fibers, so diaphragm strength strengthens, internal short-circuit rate reduces, preferably.In the reduction of internal short-circuit fraction defective, preferred further have peak frequency peak in length weighted fibre distribution of lengths histogram between 0.30 ~ 0.70mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 12%.Although the ratio with the fiber of more than 1.00mm length weighted fibre length is preferably higher, if about 50%, then enough.
In the length weighted fibre distribution of lengths histogram of the solvent-spun cellulose fibre of separator for lithium ion secondary battery (3), the slope with the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm is that the dividing plate mechanical strength of separator for lithium ion secondary battery (4) more than-3.0 and below-0.5 is high, the deviation of discharge capacity diminishes, further preferably.In separator for lithium ion secondary battery of the present invention (4), the slope with the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm to be more preferably more than-2.5 and below-0.8, more preferably more than-2.0 and below-1.0.When slope is less than-3.0, there is the situation that mechanical strength reduces.In addition, if slope exceedes-0.5, then the deviation that there is discharge capacity becomes large situation.As depicted in figs. 1 and 2, " slope is large " refers to that the length weighted fibre distribution of lengths of solvent-spun cellulose fibre is wide, and " slope is little " refers to that the length weighted fibre distribution of lengths of solvent-spun cellulose fibre is narrow, is the state that length weighted fibre length is more neat.It should be noted that, the slope of the solvent-spun cellulose fibre [I] of Fig. 1 is the slope of the solvent-spun cellulose fibre [II] of-2.9, Fig. 2 is-0.6.
It should be noted that, " there is the slope of the ratio of the fiber of the every 0.05mm fibre length between 1.00 ~ 2.00mm " as shown in Figure 3, represent the numerical value for the ratio of the fiber of the every 0.05mm length weighted fibre length had between 1.00 ~ 2.00mm, near linear is calculated, the slope of the near linear obtained by least square method.
As separator for lithium ion secondary battery of the present invention (5), preferably in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, between 0.00 ~ 1.00mm, have peak frequency peak, the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 50%.In separator for lithium ion secondary battery (5), Porous sheet material has fine and close structure, and diaphragm strength is strong, and internal short-circuit fraction defective is low, and the deviation of discharge capacity can be made little.
Fig. 4 for have peak frequency peak between 0.00 ~ 1.00mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is the length weighted fibre distribution of lengths histogram of the solvent-spun cellulose fibre of more than 50%.In mechanical strength raising, preferably in length weighted fibre distribution of lengths histogram, have peak frequency peak between 0.30 ~ 0.70mm, the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 55%.Although wish that the ratio of the fiber with more than 1.00mm length weighted fibre length is high, if about 70%, then enough.
In the length weighted fibre distribution of lengths histogram of the solvent-spun cellulose fibre of separator for lithium ion secondary battery (5), as shown in Figure 5, except above-mentioned peak frequency peak, the separator for lithium ion secondary battery (6) between 1.50 ~ 3.50mm with peak strengthens due to mechanical strength, and the deviation of discharge capacity diminishes and preferably.In addition, more preferably between 1.75 ~ 3.25mm, have peak, preferred further have peak between 2.00 ~ 3.00mm.The length weighted fibre at the peak beyond peak frequency peak is shorter in length than 1.50mm, mechanical strength likely reduces.In addition, if more than 3.50mm, then the deviation of discharge capacity likely becomes large.
As separator for lithium ion secondary battery of the present invention (7), the length weighted average fiber length that preferred solvent spins cellulose fibre is 0.50 ~ 1.25mm, and Average curl degree is less than 25.By length weighted average fiber length be 0.50 ~ 1.25mm, Average curl degree be less than 25 solvent-spun cellulose fibre and synthetic fibers be mutually wound around, the electrolyte of separator for lithium ion secondary battery guarantor fluidity can be made good, thus can internal resistance be reduced, the flash-over characteristic under high magnification particularly can be made excellent.In addition, owing to making separator for lithium ion secondary battery fine and close, so the deviation of internal short-circuit fraction defective, flash-over characteristic can be suppressed.In addition, due between synthetic fibers and length weighted average fiber length be 0.50 ~ 1.25mm, Average curl degree be less than 25 solvent-spun cellulose fibre and synthetic fibers be easily wound around, form network of fibers, so can diaphragm strength be strengthened, dividing plate can be made finer and close and thin, while can reducing internal resistance, the deviation of internal short-circuit fraction defective, flash-over characteristic can be suppressed, cycle characteristics can be made excellent.
The Average curl degree of solvent-spun cellulose fibre is more preferably less than 20, and more preferably less than 15.If the Average curl degree of solvent-spun cellulose fibre is greater than 25, then the homogeneity of dividing plate is impaired, there is the situation of the situation of internal short-circuit fraction defective rising or the remitted its fury of dividing plate.It should be noted that, the degree of crook of the numerical value little expression solvent-spun cellulose fibre of Average curl degree is little, and namely closer to linearity, therefore the lower limit of Average curl degree is without particular restriction.
The length weighted fibre length of solvent-spun cellulose fibre of the present invention and length weighted fibre distribution of lengths histogram, length weighted average fiber length, Average curl degree, according to JAPANTAPPI paper pulp test method No.52 " the fibre length test method (the automatic determination method of optics) of paper and slurry ", use KajaaniFiberLabV3.5 (MetsoAutomation Inc.) to measure.
In KajaaniFiberLabV3.5 (MetsoAutomation Inc.), for each fiber by test section, the integrated facticity length (L) of bending fiber and two ends shortest length (l) of bending fiber can be measured.The average fiber length that " length weighted average fiber length " calculates for two ends shortest length (l) measuring bending fiber." Average curl degree " is measure the integrated facticity length (L) of bending fiber and two ends shortest length (l) of bending fiber, by the value that the flexibility calculated by following formula is on average obtained for each fiber.Degree of crook along with fiber becomes large, and " flexibility " becomes large value.
Flexibility=(L/l)-1 (formula 1)
Be the solvent-spun cellulose fibre of 0 ~ 250ml as preparation political reform freedom, political reform freedom is 0 ~ 250ml and length weighted fibre length is the solvent-spun cellulose fibre of 0.20 ~ 2.00mm, political reform freedom is 0 ~ 250ml, length weighted fibre length is 0.50 ~ 1.25mm and Average curl degree is the method for the solvent-spun cellulose fibre of less than 25, can list and use fiberizer (refiner), beater (beater), mill, grinding mechanism, the rotation sword formula homogenizer of shearing force is given by High Rotation Speed sword, the dual drum type brake high speed homogenizer of shearing force is produced between the cylindrical shape inner edge and fixing outside of High Rotation Speed, the ultrasonic disintegrator of granular with the impact of ultrasonic wave generation, make it to be produced at a high speed by small-bore hole by pressure differential fiber suspension being applied at least 20MPa and make it collision and be a significant slowdown and shearing force is applied to fiber, the method of the high-pressure homogenizer of cut-out power etc.Wherein particularly preferably use the method for fiberizer.By adjusting these making beating (beating), kinds of dispersing apparatus, treatment conditions (gap, number of processes etc. between the shape of the sword of fibre concentration, temperature, pressure, revolution, fiberizer, the disk of fiberizer), target political reform freedom, length weighted fibre length and length weighted fibre distribution of lengths, Average curl degree can be reached.
As preparing the method that political reform freedom is 0 ~ 250ml, length weighted fibre length is 0.50 ~ 1.25mm, Average curl degree is the solvent-spun cellulose fibre of less than 25, be suitable for the blade type selecting fiberizer, the rotor of pulverizer, the shape of stator, undertaken pulling an oar, pulverizing as effective means by the above-mentioned device enumerated under the low concentration state that dispersion concentration is below 2.0 quality %.
The political reform freedom that separator for lithium ion secondary battery of the present invention contains 10 ~ 90 quality % is the solvent-spun cellulose fibre of 0 ~ 250ml.The content of this solvent-spun cellulose fibre is more preferably 20 ~ 70 quality %, more preferably 30 ~ 60 quality %.When the containing ratio of this solvent-spun cellulose fibre is less than 10 quality %, guarantor's fluidity of electrolyte is not enough, and internal resistance raises, or the compactness of dividing plate is not enough, and internal short-circuit fraction defective raises.When the containing ratio of this solvent-spun cellulose fibre is more than 90 quality %, the mechanical strength of dividing plate weakens, and the moisture content of dividing plate becomes many.
Separator for lithium ion secondary battery of the present invention contains the synthetic fibers of 10 ~ 90 quality %.The content of synthetic fibers is more preferably 30 ~ 80 quality %, more preferably 40 ~ 70 quality %.When the containing ratio of synthetic fibers is less than 10 quality %, the remitted its fury of dividing plate.When the containing ratio of synthetic fibers is more than 90 quality %, guarantor's fluidity of electrolyte is not enough, and internal resistance raises, or the compactness of dividing plate is not enough, and the deviation of internal short-circuit fraction defective or flash-over characteristic raises.
As separator for lithium ion secondary battery of the present invention (8), the political reform freedom of Porous sheet material preferably containing below 20 quality % is the fibrillation native cellulose fibre of 0 ~ 400ml.The content of fibrillation native cellulose fibre is more preferably below 10 quality %, more preferably below 5 quality %.Fibrillation native cellulose fibre is compared with solvent-spun cellulose fibre, and in 1 fiber, the homogeneity of thickness has the trend of variation, but has interfibrous physical entanglement and the strong feature of hydrogen bonding forces.If the containing ratio of fibrillation native cellulose fibre is more than 20 quality %, then likely because forming film in baffle surface, suppressing ionic conductivity, causing internal resistance rising or flash-over characteristic to reduce.
Fibrillation refers to it is not film-form, but formation mainly has by the threadiness of the part very finely split in the direction parallel with fiber axis, and fibre diameter is the fiber of less than 1 μm at least partially.The length-width ratio of preferred length and width is in the scope of about 20 ~ about 100000.In addition, the flat fibre length of preferred length weighting at the fiber of the scope of 0.10 ~ 2.00mm, the more preferably fiber of 0.1 ~ 1.5mm, the fiber of preferred 0.10 ~ 1.00mm further.
As the method by native cellulose fibre fibrillation, use fiberizer can be listed, beater, mill, grinding mechanism, the rotation sword formula homogenizer of shearing force is given by High Rotation Speed sword, the dual drum type brake high speed homogenizer of shearing force is produced between the cylindrical shape inner edge and fixing outside of High Rotation Speed, the ultrasonic disintegrator of granular with the impact of ultrasonic wave generation, make it to be produced at a high speed by small-bore hole by pressure differential fiber suspension being applied at least 20MPa and make it collision and be a significant slowdown and shearing force is applied to fiber, the method of the high-pressure homogenizer of cut-out power etc.Wherein particularly preferably use the method for high-pressure homogenizer.
As synthetic fibers, the ultimate fibre or composite fibre that are formed by the resin such as polyester, acrylic acid (acryl), polyolefin, full-aromatic polyester, full-aromatic polyester acid amides, polyamide, partially aromatic polyamide, Wholly aromatic polyamide, full aromatic-polyether, full aromatic polycarbonate, polyimides, polyamidoimide (PAI), polyether-ether-ketone (PEEK), polyphenylene sulfide (PPS), polyparaphenylene Ben Bing bis-oxazole (PBO), polybenzimidazoles (PBI), polytetrafluoroethylene (PTFE), ethylene-vinyl alcohol copolymer can be listed.These synthetic fibers be can be used alone or combinationally used by of more than two kinds.In addition, the synthetic fibers various Splittable conjugate fiber segmentation obtained can also be used.Wherein, preferred polyester, acrylic acid, polyolefin, full-aromatic polyester, full-aromatic polyester acid amides, polyamide, partially aromatic polyamide, Wholly aromatic polyamide, further preferred polyester, acrylic acid, polyolefin.If use polyester, acrylic acid, polyolefin, then compared with other synthetic fibers, because the easy uniform winding of solvent-spun cellulose fibre of each fiber and fibrillation forms network configuration, so the flatness on surface is higher, the separator for lithium ion secondary battery of compactness and mechanical strength can be obtained.
The fiber diameter of synthetic fibers is preferably 0.1 ~ 20 μm, is more preferably 0.1 ~ 15 μm, more preferably 0.1 ~ 10 μm.If fiber diameter is less than 0.1 μm, then fiber is meticulous, there is situation about coming off from dividing plate, if fiber diameter is coarser than 20 μm, then there is the situation being difficult to the lower thickness making dividing plate.Fiber diameter is the stereoscan photograph by dividing plate, measures the fibre diameter of the fiber forming dividing plate, the mean value of 100 of Stochastic choice.
The fibre length of synthetic fibers is preferably 0.1 ~ 15mm, is more preferably 0.5 ~ 10mm, more preferably 2 ~ 5mm.If fibre length is shorter than 0.1mm, then likely come off from dividing plate, if be longer than 15mm, then fiber likely tangles agglomerating, there is the situation producing uneven thickness.
Separator for lithium ion secondary battery of the present invention can fiber beyond the fibrillation native cellulose fibre containing political reform freedom to be the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers, political reform freedom be 0 ~ 400ml.Such as, native cellulose fibre, the slurry of native cellulose fibre, the fine strip body formed by synthetic resin, the slurry formed by synthetic resin, the fibril compound formed by synthetic resin, inorfil, political reform freedom can be listed more than the solvent-spun cellulose fibre of 250ml, political reform freedom more than the fibrillation native cellulose fibre etc. of 400ml.
As separator for lithium ion secondary battery of the present invention (9), Porous sheet material is preferably containing carboxymethyl cellulose.When forming separator for lithium ion secondary battery, be containing carboxymethyl cellulose in the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers by making political reform freedom, carboxymethyl cellulose is being adsorbed in these fibers, particularly cellulose fibre, while improving the dispersiveness of fiber, suppress torsion of fibers, improve quality when making dividing plate, mechanical strength strengthens simultaneously.In addition, due to the dehydration property of fiber moderately can be regulated, so become the pore being easy to control dividing plate sheet material, can close to desired pore-size distribution, densification and be formed uniformly dividing plate, therefore can suppress the deviation of internal short-circuit fraction defective, flash-over characteristic.
In addition, due between synthetic fibers and political reform freedom be that the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers are easily wound around, carboxymethyl cellulose makes it to strengthen, formed evenly network of fibers, thus diaphragm strength can be made to strengthen, dividing plate can be made finer and close and thin, while can reducing internal resistance, there is the deviation that can suppress internal short-circuit fraction defective, flash-over characteristic, make the preeminent effect that cycle characteristics is more excellent.
Carboxymethyl cellulose is with timber slurry, cotton linters slurry etc. for raw material, with the cellulose derivative of the Reactive Synthesis such as monochloroacetic acid, is industrially obtained by the known preparation method such as hydrophily method, solvent method.Carboxymethyl cellulose makes the various degree of polymerization by the proterties of used pulp fibres or preparation method, but be the viscosity of the 1 quality % aqueous solution be 5 ~ 16, the scope that 000mPas (0.1N-NaCl solvent, 25 DEG C, Brookfield viscometer), average degree of polymerization are 100 ~ 4,500, mean molecule quantity is 20,000 ~ 1,000,000.Involved in the present invention carboxymethyl cellulose-based upper is carboxylic acid sodium salt or sylvite, if accurate recording, is then sodium carboxymethylcellulose or potassium carboxymethylcellulose, omits the record of sodium or potassium traditionally, be only expressed as carboxymethyl cellulose.Preferably use cheapness in the present invention, easily obtain the sodium salt of the carboxymethyl cellulose of effect of the present invention.
When preparing the cellulose paste containing carboxymethyl cellulose, can list: in the solution obtained making carboxymethyl cellulose be dissolved in solvent (being generally water) in advance, add the method that fiber makes it disperse successively or simultaneously; The fiber of more than a kind is dropped into, the method mixed with the fibre stuff of other other kind prepared in the solution being dissolved with carboxymethyl cellulose in advance; Or add the method etc. of carboxymethyl cellulose to containing in the slurry of more than a kind fiber.Wherein, in the solution being dissolved with carboxymethyl cellulose, preferably prepare the method for fibre stuff.When adding fiber successively or simultaneously and make it disperse in the solution being dissolved with carboxymethyl cellulose in advance, also can add after fiber is made high concentration slurry.
In addition, when adding carboxymethyl cellulose in fibre stuff, preferred interpolation is dissolved with the solution of carboxymethyl cellulose in advance.Now, if the excessive concentration of carboxymethyl cellulose, then because viscosity is high, the diffusion in fibre stuff is deteriorated, so the concentration of carboxymethyl cellulose is preferably 0.5 ~ 5 quality %, is more preferably 0.5 ~ 3 quality %.In addition, when dissolving carboxymethyl cellulose, in the scope of carboxymethyl cellulose stabilizing dissolved, the organic solvent (such as methyl alcohol, ethanol etc.) of compatibility can be had as required with the mixing of the ratio of 10 ~ 30 quality % and glassware for drinking water relative to water.In addition, also can in the stable scope of carboxymethyl cellulose, other materials such as electrolyte such as mixing saltcake.
Carboxymethyl cellulose is owing to especially playing effect to the dispersion of the cellulosic fibres such as solvent-spun cellulose fibre or fibrillation native cellulose fibre, so when adding in preparation when adding carboxymethyl cellulose in advance in fibre stuff preparation liquid or at fibre stuff, also preferably at least use with cellulosic fibre.
Relative to the whole fiber qualities used in separator for lithium ion secondary battery of the present invention, the adding rate of carboxymethyl cellulose is preferably 0.5 ~ 2.0 quality %, more preferably 0.8 ~ 1.5 quality %.If the adding rate of carboxymethyl cellulose is less than 0.5 quality %, then there is the situation not observing the raising effect of quality etc., otherwise, if the adding rate of carboxymethyl cellulose is more than 2.0 quality %, then due to the cause of the water-retaining property of carboxymethyl cellulose, there is the situation of the drying process needing the longer time, or the moisture content of separator for lithium ion secondary battery raises, and causes dysgenic situation to battery behavior.In addition, owing to reducing drainability (Filter water-based), so the situation of reducing of the productivity when there is copy paper.
As mentioned above, carboxymethyl cellulose can make the Reactive Synthesis such as slurry raw material and monochloroacetic acid, but the carboxyl of polarity makes cellulose solubilising, easily chemical reaction occurs.Now, monochloroacetic acid etc. represent with " degree of etherification falling " relative to cellulosic Drug delivery rate.Carboxymethyl cellulose is adsorbed in fiber involved in the present invention, particularly cellulosic fibre, can improve the dispersiveness of fiber, but the high side of the degree of etherification falling of carboxymethyl cellulose improve further fiber dispersiveness and preferably.The degree of etherification falling of carboxymethyl cellulose is preferably more than 0.5, is more preferably more than 0.7.
As separator for lithium ion secondary battery of the present invention (10), as at least 1 in synthetic fibers kind, preferably containing the core-sheath-type heat fusing adhesion fiber that core is equipped with non-heat bonding composition, sheath portion is equipped with heat bonding composition.By containing core-sheath-type heat fusing adhesion fiber, core-sheath-type heat fusing adhesion fiber can be relied on to make between fiber bonding, thus the self-discharge occurred when can suppress long-term preservation under the state of high-voltage charge, so the dividing plate of voltage sustainment rate excellent can be obtained.In addition, by core-sheath-type heat fusing adhesion fiber, also can by between synthetic fibers and political reform freedom be the solvent-spun cellulose fibre of 0 ~ 250ml and the winding of synthetic fibers or by network of fibers heat bonding when not damaging porous structure that the hydrogen bond between solvent-spun cellulose is formed, strengthen diaphragm strength further.
As heat fusing adhesion fiber, the fiber (ultimate fibre) etc. that can list core-sheath-type, core shift type, Splittable, side by side type, fabric of island-in-sea type, tangerine lobe type, multiple bimetal type (multiple バ イ メ タ Le type) composite fibre or be formed by single component, core-sheath-type heat fusing adhesion fiber is due to while the fiber shape maintaining core, only make that sheath portion is softening, melting or damp and hot dissolving, make hot adhesion between fiber, so do not damage the porous structure of dividing plate and make between fiber bonding, be thus applicable to.By heating or damp and hot heating, core-sheath-type heat fusing is adhered, and the sheath portion of fiber is softening, melting or damp and hot dissolving, make heat bonding between fiber, thus the self-discharge occurred when can suppress long-term preservation under the state of high-voltage charge, so the dividing plate of voltage sustainment rate excellent can be obtained.
The resinous principle of the core and sheath portion that form core-sheath-type heat fusing adhesion fiber without particular restriction, as long as the resin for having fiber-forming ability.Such as, as the combination in core/sheath portion, PETG/polyester copolymer, PETG/polyethylene, PETG/polypropylene, PETG/ethylene-propylene copolymer, PETG/ethylene-vinyl alcohol copolymer, polypropylene, polyethylene, high-melting-point PLA/low melting point PLA etc. can be listed.Prepare from the view point of easily carrying out nonwoven fabrics, the fusing point of the resinous principle of preferred core, softening point or damp and hot solution temperature than the fusing point of the resinous principle in sheath portion or softening point high more than 20 DEG C.
As the core-sheath-type heat fusing adhesion fiber used in lithium rechargeable battery dividing plate of the present invention, core: PETG/sheath portion: the combination of polyester copolymer is because diaphragm strength raises further preferably.As the polyester copolymer used in sheath portion, preferred PETG be selected from the one kind or two or more compound copolymerization of M-phthalic acid, decanedioic acid, adipic acid, diethylene glycol (ジ エ チ Le グ リ コ ー Le), BDO etc. and the polyester copolymer that obtains.
The preferred fiber number of core-sheath-type heat fusing adhesion fiber is 0.007 ~ 1.7dtex, is more preferably 0.02 ~ 1.1dtex, more preferably 0.05 ~ 0.5dtex.When fiber number is less than 0.007dtex, there is meticulous and situation that is that come off from dividing plate, when fiber number is more than 1.7dtex, exists and become difficult and is wound around with the solvent-spun cellulose fibre of fibrillation, thus the situation of the compactness of necessity cannot be guaranteed.
The fibre length of core-sheath-type heat fusing adhesion fiber is preferably 0.1 ~ 15mm, is more preferably 0.5 ~ 10mm, more preferably 2 ~ 5mm.If fibre length is shorter than 0.1mm, then likely come off from dividing plate, if be longer than 15mm, then fiber likely tangles agglomerating, there is the situation producing uneven thickness.
In core-sheath-type heat fusing adhesion fiber separator for lithium ion secondary battery of the present invention, the containing ratio of core-sheath-type heat fusing adhesion fiber is preferably 5 ~ 40 quality %, is more preferably 8 ~ 30 quality %, more preferably 10 ~ 20 quality %.If containing ratio is less than 5 quality %, then there are the voltage sustainment rate characteristic of dividing plate or the anxiety of mechanical strength deficiency.If more than 40 quality %, then because forming film in baffle surface, suppress ionic conductivity, thus likely cause internal resistance rising or flash-over characteristic to reduce.
Separator for lithium ion secondary battery of the present invention is by using cylinder paper machine, fourdrinier paper machine, short net paper machine, apsacline paper machine, preparing from combining the damp process that compound paper machine etc. that is of the same race or xenogenesis paper machine carries out wet type copy paper among them.In raw material slurry, except fibrous raw material, be suitable for as required adding dispersant, thickener, inorganic filler, organic filler, defoamer etc., raw material slurry made the solid component concentration of about 5 ~ 0.001 quality %.This raw material slurry is diluted to normal concentration further, carries out copy paper.The separator for lithium ion secondary battery that copy paper obtains implements press polish (calender) process, hot calendered process, heat treatment etc. as required.
In addition, if carry out to blending core-sheath-type heat fusing adhesion fiber the separator for lithium ion secondary battery that copy paper obtains to implement heat treatment, then mechanical strength raises further, thus preferably.As heat treatment method, can list and use the heater such as air drier, warm-up mill, infrared ray (IR) heater, carry out heat treated continuously or while pressurization, carry out the method for heat treated.As heat treatment temperature, be preferably set to more than the adhesion sheath portion melting of fiber of core-sheath-type heat fusing or softening temperature, and the core of not enough core-sheath-type heat fusing adhesion fiber and fibers melt contained by other, the softening or temperature of decomposing.
The thickness of separator for lithium ion secondary battery of the present invention is preferably 6 ~ 50 μm, is more preferably 8 ~ 45 μm, more preferably 10 ~ 40 μm.If less than 6 μm, then exist and can not get enough mechanical strengths, or the insulating properties deficiency between positive pole and negative pole, the deviation of internal short-circuit fraction defective, flash-over characteristic raises, or the situation of capacity dimension holdup or cycle characteristics variation.If be thicker than 50 μm, then the situation that the internal resistance that there is lithium rechargeable battery raises or the situation that flash-over characteristic reduces.It should be noted that, the thickness of dividing plate of the present invention refers to the value measured according to the method specified in JISB7502, by value that outside micrometer measures when namely load is 5N.
In separator for lithium ion secondary battery of the present invention, preferred average pore size is more than 0.10 μm, and maximum diameter of hole is less than 6.0 μm.Be that the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers are wound around mutually by political reform freedom, this aperture can be reached.If average pore size is less than 0.10 μm, then the situation that the internal resistance that there is lithium rechargeable battery raises or the situation that flash-over characteristic reduces.If maximum diameter of hole is more than 6 μm, then the deviation of the internal short-circuit fraction defective or flash-over characteristic that there is lithium rechargeable battery becomes large situation.More preferably average pore size is more than 0.10 μm, and maximum diameter of hole is less than 4.0 μm, and preferably minimum-value aperture is more than 0.15 μm further, and maximum diameter of hole is less than 3.0 μm.
The basic weight of separator for lithium ion secondary battery of the present invention is preferably 5 ~ 40g/m 2, be more preferably 7 ~ 30g/m 2, more preferably 10 ~ 20g/m 2.If less than 5g/m 2, then there is the situation that can not get enough mechanical strengths, or the insulating properties deficiency between positive pole and negative pole, the situation of the deviation rising of internal short-circuit fraction defective or flash-over characteristic.If more than 40g/m 2, then the situation that the internal resistance that there is lithium rechargeable battery raises or the situation that flash-over characteristic reduces.
The layer composition of separator for lithium ion secondary battery of the present invention is without particular determination, can be the sandwich construction of single layer structure or two layers, three layers and so on, but produce from the view point of suppression micropore (pin hole), the sandwich construction of more preferably two layers, three layers and so on.In the case of the multi-layer structure, the laminating method of each layer without particular restriction, but owing to there is not the stripping of interlayer, so the compound copy paper method based on damp process compatibly can be adopted.Based on the compound copy paper method of damp process for fiber dispersion is made uniform copy paper slurry in water, this copy paper slurry paper machine of the forming net (wire) such as cylinder, fourdrinier wire, tilting at least with more than 2 is obtained fibroreticulate method.In addition, such as, when the two-layer structure be made up of top layer, nexine, each layer can be identical blending composition, also can be different, but preferably at least each layer is contain the layer of solvent-spun cellulose fibre as required composition that political reform freedom is 0 ~ 250ml.If exist not containing the layer that political reform freedom is the solvent-spun cellulose fibre of 0 ~ 250ml, then there is the peel strength of interlayer poor, can not get enough mechanical strengths, or guarantor's fluidity of electrolyte is not enough, internal resistance raises, or the compactness of dividing plate is not enough, the situation that internal short-circuit fraction defective raises.
As the negative electrode active material of lithium rechargeable battery, can use: the material with carbon element such as graphite or coke, lithium metal, be selected from the alloy of aluminium, silica, tin, nickel, more than a kind plumbous metal and lithium, SiO, SnO, Fe 2o 3, WO 2, Nb 2o 5, Li 4/3ti 5/3o 4deng metal oxide, Li 0.4the nitride such as CoN.As positive active material, cobalt acid lithium, LiMn2O4, lithium nickelate, lithium titanate, Li, Ni, Mn oxide, LiFePO4 can be used.LiFePO4 also may further be and the compound of more than a kind metal being selected from manganese, chromium, cobalt, copper, nickel, vanadium, molybdenum, titanium, zinc, aluminium, gallium, magnesium, boron, niobium.
Can be used in the electrolyte of lithium rechargeable battery in propylene glycol carbonate, ethylene carbonate ester, dimethyl carbonate, diethyl carbonate, dimethoxy-ethane, dimethoxymethane, their organic solvent such as mixed solvent and dissolve lithium salts and the electrolyte obtained.As lithium salts, lithium lithium phosphate (LiPF can be listed 6) or tetrafluoride lithium borate (LiBF 4) etc.As solid electrolyte, can be used in and dissolve lithium salts in polyethylene glycol or derivatives thereof, polymethacrylate derivative, polysiloxanes or derivatives thereof, Kynoar isogel shaped polymer and the solid electrolyte obtained.
Embodiment
Illustrate in greater detail the present invention by the following examples, but the present invention is not limited to embodiment.It should be noted that, as long as the part in embodiment or percentage are without specified otherwise, be then all benchmark with quality.
" embodiment 1 ~ 24, comparative example 1 ~ 10 "
< fiber A1>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, is that the solvent-spun cellulose fibre of 0ml is as fiber A1 using political reform freedom.
< fiber A2>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, is that the solvent-spun cellulose fibre of 120ml is as fiber A2 using political reform freedom.
< fiber A3>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, is that the solvent-spun cellulose fibre of 250ml is as fiber A3 using political reform freedom.
< fiber A4>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, is that the solvent-spun cellulose fibre of 260ml is as fiber A4 using political reform freedom.
< fiber A5>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, is that the solvent-spun cellulose fibre of 350ml is as fiber A5 using political reform freedom.
< synthetic fibers B1>
Be 3 μm using fiber diameter, fibre length is that the pet fiber of 3mm is as synthetic fibers B1.
< synthetic fibers B2>
Be 5 μm using fiber diameter, fibre length is that the acrylic fiber of 3mm is as synthetic fibers B2.
< synthetic fibers B3>
Be 4 μm using fiber diameter, fibre length is that the polypropylene fibre of 3mm is as synthetic fibers B3.
< synthetic fibers B4>
Be 10 μm using fiber diameter, fibre length be the core of 5mm is PETG (fusing point 253 DEG C), sheath portion is that the polyesters core-sheath-type heat fusing adhesion fiber of polyethyleneterephthalate-isophthalic copolymers (softening point 75 DEG C) is as synthetic fibers B4.
< synthetic fibers B5>
Be 20 μm using fiber diameter, fibre length is that the pet fiber of 5mm is as synthetic fibers B5.
< synthetic fibers B6>
Be 22 μm using fiber diameter, fibre length is that the pet fiber of 5mm is as synthetic fibers B6.
< synthetic fibers B7>
Be 0.1 μm using fiber diameter, fibre length is that the pet fiber of 2mm is as synthetic fibers B7.
< synthetic fibers B8>
Be 0.08 μm using fiber diameter, fibre length is that the pet fiber of 2mm is as synthetic fibers B8.
< fibrillation native cellulose fibre C1>
Use high-pressure homogenizer process cotton linters, preparation political reform freedom is the fibrillation native cellulose fibre C1 of 0ml.
< fibrillation native cellulose fibre C2>
Use high-pressure homogenizer process cotton linters, preparation political reform freedom is the fibrillation native cellulose fibre C2 of 270ml.
< fibrillation native cellulose fibre C3>
Use high-pressure homogenizer process cotton linters, preparation political reform freedom is the fibrillation native cellulose fibre C3 of 400ml.
< fibrillation native cellulose fibre C4>
Use high-pressure homogenizer process cotton linters, preparation political reform freedom is the fibrillation native cellulose fibre C4 of 500ml.
< fiber D1>
Using the contraposition system Wholly aromatic polyamide that fiberizer process fiber diameter is 10 μm, fibre length is 3mm, is that the fibrillation contraposition system fully aromatic polyamide fiber of 500ml is as fiber D1 using political reform freedom.
< fiber E1>
Be that the flaxen fiber of 7 μm is as fiber E1 using fiber diameter.
[table 1]
In Table 1, " kind " of synthetic fibers and other fiber is as follows:
" PET ": pet fiber
" AA ": acrylic fiber
" PP ": polypropylene fibre
" PET/PEs-C ": Polyester core-sheath-type heat fusing adhesion fiber
" PA ": fibrillation contraposition system fully aromatic polyamide fiber.
Embodiment 1 ~ 24 and comparative example 1 ~ 10
< dividing plate >
According to raw material as shown in table 1 and content, preparation copy paper slurry, uses cylinder paper machine to carry out wet type copy paper, the dividing plate of preparation embodiment 1 ~ 24 and comparative example 1 ~ 9.Thickness is by room temperature carrying out press polish process to adjust.In addition, using the dividing plate of porous polyethylene film (thickness 22 μm, porosity 40%) as comparative example 10.
< lithium rechargeable battery A>
[preparation of negative pole 1]
Mix the Kynoar of the native graphite of 97 quality %, 3 quality %, the slurry that they are scattered in METHYLPYRROLIDONE and obtain by preparation, coating thickness is after the two sides of the Copper Foil of 15 μm is rolled, in 150 DEG C of vacuumizes 2 hours, prepare the lithium ion secondary battery cathode that thickness is 100 μm, it can be used as negative pole 1.
[preparation of positive pole 1]
Mix the LiMn of 95 quality % 2o 4, the acetylene black of 2 quality %, the Kynoar of 3 quality %, the slurry that they are scattered in METHYLPYRROLIDONE and obtain by preparation, coating thickness is after the two sides of the aluminium foil of 20 μm is rolled, in 150 DEG C of vacuumizes 2 hours, prepare the lithium ion secondary battery anode that thickness is 100 μm, it can be used as positive pole 1.
[preparation of lithium rechargeable battery A]
Winding negative pole 1 and positive pole 1, make the dividing plate of embodiment 1 ~ 24 and comparative example 1 ~ 7,9 respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 150 DEG C of vacuumizes 10 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, the lithium rechargeable battery A of preparation embodiment 1 ~ 24 and comparative example 1 ~ 7,9.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
Winding negative pole 1 and positive pole 1, make the dividing plate of comparative example 8 respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 110 DEG C of vacuumizes 24 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, prepares the lithium rechargeable battery A of comparative example 8.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
In addition, winding negative pole 1 and positive pole 1, make the dividing plate of comparative example 10 between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 80 DEG C of vacuumizes 10 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, prepares the lithium rechargeable battery A of comparative example 10.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
< lithium rechargeable battery B>
[preparation of negative pole 2]
Mix the carbonaceous mesophase spherules of 81 quality %, the acetylene black of 14 quality %, the polytetrafluoroethylene of 5 quality %, the slurry that they are scattered in METHYLPYRROLIDONE and obtain by preparation, coating thickness is after the two sides of the Copper Foil of 15 μm is rolled, in 150 DEG C of vacuumizes 2 hours, prepare the lithium ion secondary battery cathode that thickness is 100 μm, it can be used as negative pole 2.
[preparation of positive pole 2]
Mix the LiMn of 95 quality % 2o 4, the acetylene black of 2 quality %, the polytetrafluoroethylene of 3 quality %, the slurry that they are scattered in METHYLPYRROLIDONE and obtain by preparation, coating thickness is after the two sides of the aluminium foil of 20 μm is rolled, in 150 DEG C of vacuumizes 2 hours, prepare the lithium ion secondary battery anode that thickness is 100 μm, it can be used as positive pole 2.
[preparation of lithium rechargeable battery B]
According to the order laminating of the dividing plate of embodiment 1 ~ 24 and comparative example 1 ~ 7,9, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 140 DEG C of vacuumizes 10 hours, they are let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery B (battery capacity=30mAh equivalent).
According to the order laminating of the dividing plate of comparative example 8, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 110 DEG C of vacuumizes 24 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery B (battery capacity=30mAh equivalent).
According to the order laminating of the dividing plate of comparative example 10, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 80 DEG C of vacuumizes 15 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery B (battery capacity=30mAh equivalent).
For dividing plate and the lithium rechargeable battery of embodiment and comparative example, carry out following evaluation, the results are shown in table 2 and table 3.
[basic weight]
Basic weight is measured according to JISP8124.
[thickness]
According to the method specified in JISB7502, by outside micrometer when namely load is 5N, measure thickness.
[pore size determination]
For prepared dividing plate, use PMI Inc., trade name: パ ー system Port ロ メ ー タ ー (Perm-Porometer) CFP-1500A, measure according to JISK3832, ASTMF316-86, ASTME1294-89, measure the maximum diameter of hole of each base material, average pore size.
[dividing plate moisture content]
Be determined at that temperature is 20 DEG C, humidity is after the sample mass of the dividing plate placing 2 under the condition of 55%, in 105 DEG C of dryings 4 hours.Then, after letting cool in desiccator, obtain loss on drying by quality measurement, calculate dividing plate moisture content according to following formula.
Dividing plate moisture content (%)=(loss on drying (g)/sample mass (g)) × 100
[diaphragm strength]
The metal needle of to be the diameter of the circle of 1.6 with curvature by front end be 1mm is installed on desk-top Material Testing Machine (Co., Ltd. オ リ エ Application テ ッ Network (OrientecCo., LTD.) make, trade name: STA-1150), at right angles drop to the constant speed of 1mm/s relative to sample face and run through.Measure peak load (g) now, it can be used as diaphragm strength.
[table 2]
[internal resistance]
Under 1C, each 100 chargings of the lithium rechargeable battery A of embodiment and comparative example, after 30 minutes, are measured to internal resistance, calculate each mean value under the interchange of 1kHz.
[internal short-circuit fraction defective]
Use each 100 of the lithium rechargeable battery A of embodiment and comparative example, calculate charging/discharging voltage scope be 2.8 ~ 4.2V, charging and discharging currents determines the internal short-circuit fraction defective of electric 500 circulation times of current charge-discharge repeatedly under being 1C.
[C multiplying power discharging test (discharge capacity)]
Use each 50 of the lithium rechargeable battery B of embodiment and comparative example, carry out 3 circulations aging (ageing) under 1C after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), each mean value of discharge capacity when calculating 0.2C and 5C.
[C multiplying power discharging test (deviation of discharge capacity)]
Use each 50 of the lithium rechargeable battery B of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), according to discharge capacity during following standard evaluation 0.2C and 5C.
◎: the difference of discharge capacity is less than 1.0% relative to mean value.
Zero: the difference of discharge capacity relative to mean value more than 1.0% and be less than 2.5%.
△: the difference of discharge capacity relative to mean value more than 2.5% and be less than 5.0%.
×: the difference of discharge capacity relative to mean value more than 5.0%.
[cycle characteristics (the capacity dimension holdup after 100 circulations)]
Use each 20 of the lithium rechargeable battery B of embodiment and comparative example, carry out constant-current constant-voltage charging (1/10C cut-out) under 1C, 4.2V after, under the condition of 1C, carry out constant-current discharge test (2.8V cut-out), calculate the mean value of the capacity dimension holdup after 100 circulations (circulate for 100 times rear/1 circulation volume).
[table 3]
As shown in table 2, the separator for lithium ion secondary battery of embodiment 1 ~ 24 due to the political reform freedom containing 10 ~ 90 quality % be the solvent-spun cellulose fibre of 0 ~ 250ml, the synthetic fibers of 10 ~ 90 quality %, so moisture content is low, mechanical strength is strong, excellent.
That is, the separator for lithium ion secondary battery of embodiment 1 ~ 24 is due to the synthetic fibers containing 10 ~ 90 quality %, so compare with the dividing plate made of paper be made up of with flaxen fiber solvent-spun cellulose of comparative example 8, moisture content can be suppressed in low-level.In addition, owing to being easily wound around between fiber, easily network of fibers is formed, so the intensity enhancing of dividing plate.On the other hand, the separator for lithium ion secondary battery of comparative example 1 due to the political reform freedom in dividing plate be that the containing ratio of the solvent-spun cellulose fibre of 0 ~ 250ml is more than 90 quality %, the synthetic fibers contained in dividing plate are less than 10 quality %, so moisture content is high, diaphragm strength weakens.The separator for lithium ion secondary battery of comparative example 4 is less than 10 quality %, so diaphragm strength weakens due to the containing ratio of the synthetic fibers in dividing plate.Although the separator for lithium ion secondary battery of comparative example 9 is containing fibrillation heat resistant fibre, because the political reform freedom of solvent-spun cellulose fibre is more than 250ml, so diaphragm strength weakens.
As shown in table 3, the lithium rechargeable battery of embodiment 1 ~ 24 due to use by the political reform freedom containing 10 ~ 90 quality % be the solvent-spun cellulose fibre of 0 ~ 250ml, the dividing plate that formed of the Porous sheet material of the synthetic fibers of 10 ~ 90 quality %, so internal resistance, flash-over characteristic under internal short-circuit fraction defective, particularly high magnification and deviation, cycle characteristics excellence.
Namely, the lithium rechargeable battery of embodiment 1 ~ 24 due to the political reform freedom that dividing plate contains 10 ~ 90 quality % be the solvent-spun cellulose fibre of 0 ~ 250ml, so guarantor's fluidity of electrolyte is good, ionic conductivity can be made good, therefore, while low internal resistance is shown, the flash-over characteristic particularly under high magnification, cycle characteristics are excellent.On the other hand, the lithium rechargeable battery of comparative example 2 and 3 is less than 10 quality % due to the containing ratio that political reform freedom is the solvent-spun cellulose fibre of 0 ~ 250ml, the lithium rechargeable battery of comparative example 6,7,10 is the solvent-spun cellulose fibre of 0 ~ 250ml because dividing plate does not contain political reform freedom, so guarantor's fluidity of electrolyte is poor, internal resistance illustrates high numerical value.
The lithium rechargeable battery of embodiment 1 ~ 24 due to the political reform freedom containing 10 ~ 90 quality % in dividing plate be the solvent-spun cellulose fibre of 0 ~ 250ml, so dividing plate can be made fine and close, therefore the deviation of internal short-circuit fraction defective, discharge capacity is low, excellent.On the other hand, the lithium rechargeable battery of comparative example 2,3 is less than 10 quality % due to the containing ratio that the political reform freedom in dividing plate is the solvent-spun cellulose fibre of 0 ~ 250ml, the compactness of dividing plate is not enough, so the deviation of internal short-circuit fraction defective, discharge capacity raises.The lithium rechargeable battery of comparative example 5 is greater than 0 ~ 250ml due to the political reform freedom of the solvent-spun cellulose fibre in dividing plate, and the compactness of dividing plate is not enough, so internal short-circuit fraction defective slightly raises.The lithium rechargeable battery of comparative example 6,7 is the solvent-spun cellulose fibre of 0 ~ 250ml because dividing plate does not contain political reform freedom, so the compactness of dividing plate is not enough, the deviation of internal short-circuit fraction defective, discharge capacity raises.Use the internal resistance of the lithium rechargeable battery of the comparative example 10 of porous polyethylene film high, powerful discharge capacity is poor.
The political reform freedom of lithium rechargeable battery containing 5 quality % in dividing plate of embodiment 8 is the fibrillation native cellulose fibre of 0 ~ 400ml.The political reform freedom of lithium rechargeable battery containing 10 quality % in dividing plate of embodiment 9 ~ 12 is the fibrillation native cellulose fibre of 0 ~ 400ml.The political reform freedom of lithium rechargeable battery containing 20 quality % in dividing plate of embodiment 13 is the fibrillation native cellulose fibre of 0 ~ 400ml.Therefore, dividing plate can be made finer and close and thin, compared with the lithium rechargeable battery of embodiment 1 ~ 7,15 ~ 18, the internal resistance of lithium-ion secondary battery of embodiment 8 ~ 13 is low, and powerful discharge capacity illustrates high numerical value.
The lithium rechargeable battery of embodiment 9 ~ 12 is used in the dividing plate of fibrillation native cellulose fibre C1 ~ C4 that blending under same basic weight, same thickness has respective political reform freedom different.Blending is used to have political reform freedom to be greater than the compactness of lithium rechargeable battery when making the lower thickness of dividing plate of the embodiment 12 of the dividing plate of the fibrillation native cellulose fibre C4 of 400ml slightly not enough, have political reform freedom to be compared with the lithium rechargeable battery of the embodiment 9 ~ 11 of the dividing plate of the fibrillation native cellulose fibre C1 ~ C3 of 0 ~ 400ml with use blending, internal short-circuit fraction defective slightly raises.
The lithium rechargeable battery of embodiment 14 due to the political reform freedom in dividing plate be that the containing ratio of the fibrillation native cellulose fibre of 0 ~ 400ml is more than 20 quality %, so dividing plate becomes too fine and close slightly, ionic conductivity is slightly deteriorated, compared with the lithium rechargeable battery of embodiment 1 ~ 13,15 ~ 17,19,20, internal resistance illustrates slightly high numerical value, and powerful discharge capacity illustrates lower slightly numerical value.
The lithium rechargeable battery of embodiment 18 due to basic weight bigger, the thickness of dividing plate is slightly thick, and average pore size is smaller, so compared with the lithium rechargeable battery of embodiment 1 ~ 13,15 ~ 17,19,20, internal resistance illustrates slightly high numerical value, and powerful discharge capacity illustrates lower slightly numerical value.
The lithium rechargeable battery of embodiment 20 due to basic weight smaller, the thickness of dividing plate is slightly thin, and maximum diameter of hole is bigger, so compared with the lithium rechargeable battery of embodiment 1 ~ 11,13 ~ 19, the deviation of internal short-circuit fraction defective, discharge capacity slightly raises.
The lithium rechargeable battery of embodiment 22 due to the fiber diameter of used synthetic fibers slightly thick, so compared with the lithium rechargeable battery of embodiment 21, diaphragm strength is slightly weak, and the deviation of discharge capacity slightly raises.
The lithium rechargeable battery of embodiment 24 due to the fiber diameter of used synthetic fibers slightly thin, so compared with the lithium rechargeable battery of embodiment 23, diaphragm strength is slightly weak, and cycle characteristics is slightly poor.
" embodiment 25 ~ 59, comparative example 11 ~ 18 "
< solvent-spun cellulose fibre >
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, and preparation has the solvent-spun cellulose fibre of the physical property of table 4 and table 5.
The physics value > of < solvent-spun cellulose fibre
For the solvent-spun cellulose fibre prepared according to said method, to represent as follows
(1) there is the ratio of the fiber of more than 1.00mm length weighted fibre length: " proportion of fibers of more than 1.00mm "
(2) the length weighted fibre length at the peak frequency peak in length weighted fibre distribution of lengths histogram: " fibre length at peak frequency peak "
(3) in length weighted fibre distribution of lengths histogram, there is the slope of the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm: " slope of ratio "
(4) length weighted average fiber length: " average fiber length "
(5) except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm as sieve plate, sample solution concentration is set to beyond 0.1 quality %, the freedom according to JISP8121 measures: " political reform freedom ",
Be illustrated in table 4.
[table 4]
For the solvent-spun cellulose fibre prepared according to said method, to represent as follows
(1) there is the ratio of the fiber of more than 1.00mm length weighted fibre length: " proportion of fibers of more than 1.00mm "
(2) the length weighted fibre length at the peak frequency peak in length weighted fibre distribution of lengths histogram: " fibre length at peak frequency peak "
(3) the length weighted fibre length at the peak beyond peak frequency peak: " fibre length at the 2nd peak "
(4) length weighted average fiber length: " average fiber length "
(5) except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm as sieve plate, sample solution concentration is set to beyond 0.1 quality %, the freedom according to JISP8121 measures: " political reform freedom ",
Be illustrated in table 5.
[table 5]
< fibrillation native cellulose fibre >
Use high-pressure homogenizer process cotton linters, preparation political reform freedom is the fibrillation native cellulose fibre of 0ml, 270ml, 400ml, 500ml.
< dividing plate >
Raw material according to table 6 and table 7 and content, preparation copy paper slurry, uses cylinder paper machine to carry out wet type copy paper, the dividing plate of preparation embodiment and comparative example.Thickness is by room temperature carrying out press polish process to adjust.
[table 6]
[table 7]
In table 6 and table 7, " kind " of synthetic fibers 1 ~ 3 is as follows:
" PET ": PETG
" AA ": acrylic fiber
" PP ": polypropylene fibre
" NY ": nylon 66 fiber
" PET-B1 ": the pet fiber that do not stretch (fusing point 130 DEG C).
< lithium rechargeable battery C>
Winding negative pole 1 and positive pole 1, make the dividing plate of embodiment and comparative example respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 110 DEG C of vacuumizes 15 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, the lithium rechargeable battery C of preparation embodiment and comparative example.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
< lithium rechargeable battery D>
According to the order laminating of the dividing plate of embodiment and comparative example, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 110 DEG C of vacuumizes 15 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery D (battery capacity=30mAh equivalent).
For dividing plate and the lithium rechargeable battery of embodiment and comparative example, carry out the evaluation of deviation of basic weight, thickness, maximum diameter of hole, average pore size, diaphragm strength, internal short-circuit fraction defective, 5C discharge capacity, capacity dimension holdup, discharge capacity, the results are shown in table 8.
[protecting liquid rate]
After the dividing plate being cut into the square embodiment of 10cm and comparative example is flooded 1 minute in propylene carbonate, vertically suspend in midair, keep 15 minutes.
Protect liquid rate (%)=(impregnated in the partition quality of partition quality/maintenance after 15 minutes before propylene carbonate) × 100
Calculate by this and protect liquid rate, evaluate according to following standard.
◎: protecting liquid rate is more than 200%.
Zero: protect liquid rate and be more than 150% and less than 200%.
△: protect liquid rate and be more than 50% and less than 150%.
×: protect liquid rate less than 50%.
[internal short-circuit fraction defective]
Use each 100 of the lithium rechargeable battery C of embodiment and comparative example, calculate charging/discharging voltage scope be 2.8 ~ 4.2V, charging and discharging currents determines the internal short-circuit fraction defective of electric 100 circulation times of current charge-discharge repeatedly under being 1C.
[C multiplying power discharging test (discharge capacity) (deviation of discharge capacity)]
Use each 50 of the lithium rechargeable battery D of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, under 5C, carry out constant-current discharge test (2.8V cut-out), calculate the mean value of discharge capacity.In addition, calculate the deviation of discharge capacity, evaluate according to following standard.
(deviation of discharge capacity)
◎: the difference of discharge capacity is less than 1.0% relative to mean value.
Zero: the difference of discharge capacity relative to mean value more than 1.0% and be less than 2.5%.
△: the difference of discharge capacity relative to mean value more than 2.5% and be less than 5.0%.
×: the difference of discharge capacity relative to mean value more than 5.0%.
[cycle characteristics (the capacity dimension holdup after 100 circulations)]
Use each 10 of the lithium rechargeable battery C of embodiment and comparative example, carry out constant-current constant-voltage charging (1/10C cut-out) under 1C, 4.2V after, under the condition of 1C, carry out constant-current discharge test (2.8V cut-out).Calculate the mean value of the capacity dimension holdup after 100 circulations (circulate for 100 times rear/1 circulation volume).
[table 8]
As shown in table 8, the separator for lithium ion secondary battery of embodiment 26 ~ 59 is 0 ~ 250ml and length weighted average fiber length is the solvent-spun cellulose fibre of 0.20 ~ 2.00mm, the synthetic fibers of 10 ~ 90 quality % due to the political reform freedom containing 10 ~ 90 quality %, so be easily wound around between fiber, easy formation network of fibers, therefore liquid rate is protected high, the intensity enhancing of dividing plate.In addition, the lithium rechargeable battery of embodiment 26 ~ 59 is owing to using the political reform freedom containing 10 ~ 90 quality % to be 0 ~ 250ml and length weighted average fiber length is the dividing plate of the solvent-spun cellulose fibre of 0.20 ~ 2.00mm, the synthetic fibers of 10 ~ 90 quality %, so the electrolyte guarantor liquid rate of dividing plate is high, ionic conductivity can be made good, and the flash-over characteristic therefore particularly under high magnification, cycle characteristics are excellent.In addition, due to dividing plate can be made fine and close, so the deviation of internal short-circuit fraction defective, discharge capacity is low, excellent.
On the other hand, the separator for lithium ion secondary battery of embodiment 25 is shorter than 0.20mm, so diaphragm strength slightly weakens due to the average fiber length of the solvent-spun cellulose fibre in dividing plate.The separator for lithium ion secondary battery of embodiment 25 is shorter than 0.20mm due to the weight averaged fiber length of the solvent-spun cellulose fibre in dividing plate, so be difficult between fiber be wound around, become and be difficult to form network of fibers, therefore the deviation of internal short-circuit fraction defective, discharge capacity is slightly high.
The separator for lithium ion secondary battery of comparative example 11 and 12 is because the political reform freedom of the solvent-spun cellulose fibre in dividing plate is more than 250ml, average fiber length is more than 2.00mm, so the compactness of dividing plate is not enough, the internal short-circuit fraction defective of the lithium rechargeable battery of comparative example 11 and 12, the deviation of discharge capacity raise.The separator for lithium ion secondary battery of comparative example 13 ~ 16, due to not containing solvent-spun cellulose fibre, reduces so protect liquid rate.In addition, the lithium rechargeable battery of comparative example 13 ~ 16 is owing to using the dividing plate not containing solvent-spun cellulose fibre, so the compactness of dividing plate is not enough, internal short-circuit fraction defective raises.The lithium rechargeable battery of comparative example 17 is owing to forming containing the synthetic fibers more than 90 quality %, so can not get enough compactness, internal short-circuit fraction defective is high, protects liquid rate and reduces.The lithium rechargeable battery of comparative example 18 because the containing ratio of synthetic fibers is less than 10 quality %, so diaphragm strength weakens.
If comparing embodiment 26 ~ 39, then embodiment 36 and 39 lithium rechargeable battery due in the fiber length distribution histogram of solvent-spun cellulose fibre peak frequency peak be longer than 0.00 ~ 1.00mm, so the compactness of dividing plate is not enough, compared with embodiment 26 ~ 35, internal short-circuit fraction defective slightly raises, and the deviation of discharge capacity becomes large.The lithium rechargeable battery of embodiment 37 and 38 owing to having the ratio of the fiber of more than 1.00mm fibre length less than 10% in the fiber length distribution histogram of solvent-spun cellulose fibre, so diaphragm strength slightly weakens, compared with embodiment 26 ~ 35,5C discharge capacity slightly reduces.
If comparing embodiment 26 ~ 35, then the lithium rechargeable battery of embodiment 26 ~ 29,31 ~ 34 is because the slope in the fiber length distribution histogram of solvent-spun cellulose fibre with the ratio of the fiber of the every 0.05mm fibre length between 1.00 ~ 2.00mm is for more than-3.0 and below-0.5, so diaphragm strength is high, the deviation of discharge capacity diminishes.The lithium rechargeable battery of embodiment 30 owing to having the slope of the ratio of the fiber of the every 0.05mm fibre length between 1.00 ~ 2.00mm for below-3.0 in the fiber length distribution histogram of solvent-spun cellulose fibre, so compared with embodiment 26 ~ 29,31 ~ 34, diaphragm strength is lower slightly, and the deviation of discharge capacity becomes large.Slope exceedes the lithium rechargeable battery of the embodiment 35 of-0.5 compared with embodiment 26 ~ 29,31 ~ 34, and the deviation of discharge capacity becomes large.
If comparing embodiment 40 ~ 50, then the lithium rechargeable battery of embodiment 40 ~ 48 is more than 50% owing to having peak frequency peak between 0.00 ~ 1.00mm in the fiber length distribution histogram of solvent-spun cellulose fibre, having the ratio of the fiber of more than 1.00mm fibre length, so have fine and close structure, diaphragm strength is strong, internal short-circuit fraction defective is low, and the deviation of discharge capacity diminishes.The lithium rechargeable battery of embodiment 49 due in the fiber length distribution histogram of solvent-spun cellulose fibre peak frequency peak be longer than 0.00 ~ 1.00mm, so internal short-circuit rate is slightly poor.The lithium rechargeable battery of embodiment 50 due in the fiber length distribution histogram of solvent-spun cellulose fibre, there is between 0.00 ~ 1.00mm peak frequency peak but the ratio with the fiber of more than 1.00mm fibre length less than 50%, so compared with embodiment 40 ~ 48, diaphragm strength weakens.
If comparing embodiment 40 ~ 48, then embodiment 40 ~ 42,44 ~ 47 lithium rechargeable battery due in the fiber length distribution histogram of solvent-spun cellulose fibre except peak frequency peak with except between 1.50 ~ 3.50mm, there is peak, so more easily form network of fibers, therefore diaphragm strength is strong, internal short-circuit fraction defective is low, and the deviation of discharge capacity diminishes.The lithium rechargeable battery of embodiment 43 is less than 1.50mm due to the peak beyond peak frequency peak in the fiber length distribution histogram of solvent-spun cellulose fibre, so compared with embodiment 40 ~ 42,44 ~ 47, diaphragm strength is slightly weak, and the deviation of discharge capacity slightly becomes large.The lithium rechargeable battery of embodiment 48 is greater than 3.50mm due to the peak beyond peak frequency peak in the fiber length distribution histogram of solvent-spun cellulose fibre, so compared with embodiment 40 ~ 42,44 ~ 47, internal short-circuit fraction defective is slightly high, and the deviation of discharge capacity slightly becomes large.
The lithium rechargeable battery of embodiment 26 ~ 54 due to the political reform freedom containing below 20 quality % in dividing plate be the fibrillation native cellulose fibre of 0 ~ 400ml, so dividing plate can be made finer and close, with embodiment 58 with 59 lithium rechargeable battery compare, internal short-circuit fraction defective reduce.The lithium rechargeable battery of embodiment 55 is the dividing plate of fibrillation native cellulose fibre more than 20 quality % of 0 ~ 400ml owing to using political reform freedom, so dividing plate becomes too fine and close slightly, ionic conductivity is slightly deteriorated, and powerful discharge capacity and the capacity dimension holdup after circulating for 100 times illustrate lower slightly numerical value.The lithium rechargeable battery of embodiment 56 is greater than 400ml due to the political reform freedom of fibrillation native cellulose fibre, so the compactness of dividing plate slightly declines, compares with 53 with embodiment 40, and diaphragm strength reduces.
" embodiment 60 ~ 88, comparative example 19 ~ 21 "
< solvent-spun cellulose fibre >
Be 10 μm by fiber diameter, fibre length is after the beating consistency dispersion recorded with table 9 of the untreated solvent-spun cellulose fibre of 4mm, change the processing time with Xiang Chuan ironworker society dual disc fiberizer, carry out making beating and process.The length weighted average fiber length of various treated solvent-spun cellulose fibre and average crimpness are illustrated in table 9.
[table 9]
< fibrillation native cellulose fibre >
By special for eastern nation パ Le プ society (TOHOTOKUSHUPULPCo.LTD.) cotton pulp processed, change number of processes with high-pressure homogenizer, make the fibrillation native cellulose fibre of the length weighted average fiber length that table 10 is recorded.
[table 10]
< dividing plate >
According to raw material as shown in table 11 and content, preparation copy paper slurry, uses cylinder paper machine to carry out wet type copy paper, the dividing plate of preparation embodiment 60 ~ 88 and comparative example 19 ~ 21.Thickness is by room temperature carrying out press polish process to adjust.
[table 11]
In table 11, " kind " of synthetic fibers is as follows:
" PET ": pet fiber
" AA ": acrylic fiber
" PP ": polypropylene fibre
" PET/PEs-C ": polyesters core-sheath-type heat fusing adhesion fiber.
< lithium rechargeable battery E>
Winding negative pole 1 and positive pole 1, make the dividing plate of embodiment 60 ~ 88 and comparative example 19 ~ 21 respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 150 DEG C of vacuumizes 10 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, the lithium rechargeable battery E of preparation embodiment 60 ~ 88 and comparative example 19 ~ 21.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
< lithium rechargeable battery F>
According to the order laminating of the dividing plate of embodiment and comparative example, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 110 DEG C of vacuumizes 15 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery F (battery capacity=30mAh equivalent).
For dividing plate and the lithium rechargeable battery of embodiment and comparative example, carry out basic weight, thickness, dividing plate moisture content, diaphragm strength, maximum diameter of hole, average pore size, internal resistance, internal short-circuit fraction defective, discharge capacity, the deviation of discharge capacity, the evaluation of capacity dimension holdup, the results are shown in table 11 and table 12.
[internal resistance]
Under 1C, each 100 chargings of the lithium rechargeable battery E of embodiment and comparative example, after 30 minutes, are measured to internal resistance, calculate each mean value under the interchange of 1kHz.
[internal short-circuit fraction defective]
Use each 100 of the lithium rechargeable battery E of embodiment and comparative example, calculate charging/discharging voltage scope be 2.8 ~ 4.2V, charging and discharging currents determines the internal short-circuit fraction defective of electric 500 circulation times of current charge-discharge repeatedly under being 1C.
[C multiplying power discharging test (discharge capacity)]
Use each 50 of the lithium rechargeable battery F of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), each mean value of discharge capacity when calculating 0.2C and 5C.
[C multiplying power discharging test (deviation of discharge capacity)]
Use each 50 of the lithium rechargeable battery F of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), according to discharge capacity during following standard evaluation 0.2C and 5C.
◎: the difference of discharge capacity is less than 1.0% relative to mean value.
Zero: the difference of discharge capacity relative to mean value more than 1.0% and be less than 2.5%.
△: the difference of discharge capacity relative to mean value more than 2.5% and be less than 5.0%.
×: the difference of discharge capacity relative to mean value more than 5.0%.
[cycle characteristics (the capacity dimension holdup after 100 circulations)]
Use each 20 of the lithium rechargeable battery F of embodiment and comparative example, carry out constant-current constant-voltage charging (1/10C cut-out) under 1C, 4.2V after, under the condition of 1C, carry out constant-current discharge test (2.8V cut-out), calculate the mean value of the capacity dimension holdup after 100 circulations (circulate for 100 times rear/1 circulation volume).
[table 12]
As shown in table 11, the separator for lithium ion secondary battery of embodiment 60 ~ 86 due to the length weighted average fiber length containing 10 ~ 90 quality % be 0.50 ~ 1.25mm, Average curl degree is the solvent-spun cellulose fibre of less than 25, the synthetic fibers of 10 ~ 90 quality %, so moisture content is low, mechanical strength is strong, excellent.
By embodiment 61,69 ~ 71 and comparative example 20,21 are compared, the length weighted average fiber length of cause containing 10 ~ 90 quality % is 0.50 ~ 1.25mm, Average curl degree is the solvent-spun cellulose fibre of less than 25, the synthetic fibers of 10 ~ 90 quality %, can suppress the moisture content of dividing plate in low-level.In addition, owing to making easily to be wound around between fiber, easily form network of fibers, so the intensity enhancing of dividing plate.
By comparing known by embodiment 60 ~ 65 and embodiment 87,88, because the length weighted average fiber length of solvent-spun cellulose fibre is 0.50 ~ 1.25mm, making easily to be wound around between fiber, easily forming network of fibers, diaphragm strength strengthens.When the length weighted average fiber curtailment 0.50mm of solvent-spun cellulose fibre (embodiment 87), when preparing dividing plate, fiber becomes and easily comes off from the forming net of paper machine, and the intensity of dividing plate slightly difficulty manifests.In the length weighted average fiber length of solvent-spun cellulose fibre more than in the situation (embodiment 88) of 1.25mm, become the mass uniformity being easy to damage dividing plate, the intensity of dividing plate slightly diminishes, and the maximum diameter of hole of dividing plate slightly becomes large.
By comparing known by embodiment 61,66 ~ 68 and comparative example 19, because the Average curl degree of solvent-spun cellulose fibre is less than 25, is easily wound around, easily forms network of fibers between fiber, the maximum diameter of hole of dividing plate is also adjusted to little value.
As shown in table 12, the lithium rechargeable battery of embodiment 60 ~ 86 due to use by the length weighted average fiber length containing 10 ~ 90 quality % be 0.50 ~ 1.25mm, Average curl degree is the solvent-spun cellulose fibre of less than 25, the dividing plate that the Porous sheet material of the synthetic fibers of 10 ~ 90 quality % is formed, so internal resistance, flash-over characteristic under internal short-circuit fraction defective, particularly high magnification and deviation thereof, cycle characteristics are excellent.
Namely, the lithium rechargeable battery of embodiment 60 ~ 86 due to the length weighted average fiber length containing 10 ~ 90 quality % be 0.50 ~ 1.25mm, Average curl degree is the solvent-spun cellulose fibre of less than 25, so guarantor's fluidity of electrolyte is good, ionic conductivity can be made good, therefore, while low internal resistance is shown, the flash-over characteristic particularly under high magnification, cycle characteristics are excellent.On the other hand, the lithium rechargeable battery of comparative example 20 due to length weighted average fiber length be 0.50 ~ 1.25mm, Average curl degree is that the containing ratio of the solvent-spun cellulose fibre of less than 25 is less than 10 quality %, so guarantor's fluidity of electrolyte is poor, internal resistance illustrates high numerical value.The lithium rechargeable battery of comparative example 19 is greater than 25 due to the Average curl degree of solvent-spun cellulose fibre, so the mass uniformity of dividing plate is impaired, the deviation of internal short-circuit fraction defective, discharge capacity raises.
The political reform freedom of lithium rechargeable battery containing 10 quality % in dividing plate of embodiment 80 ~ 83 is the fibrillation native cellulose fibre of 0 ~ 400ml.Like this, by making in dividing plate containing the fibrillation native cellulose that political reform freedom is 0 ~ 400ml, the intensity of dividing plate can be improved, make dividing plate thinner, compared with the lithium rechargeable battery of embodiment 61,79,84, the internal resistance of lithium-ion secondary battery of embodiment 80 ~ 83 is low, and powerful discharge capacity illustrates high numerical value.
The lithium rechargeable battery of embodiment 86 due in dividing plate length weighted average fiber length be that the containing ratio of the fibrillation native cellulose fibre of 0.20 ~ 1.00mm is more than 20 quality %, so dividing plate becomes too fine and close slightly, average pore size also diminishes, ionic conductivity is slightly deteriorated, compared with the lithium rechargeable battery of embodiment 81, embodiment 85, internal resistance illustrates slightly high numerical value, and powerful discharge capacity illustrates lower slightly numerical value.
According to the comparison of embodiment 60 ~ 65,69 ~ 71, the lithium rechargeable battery of embodiment 64,65,69 is greater than 6.0 μm due to maximum diameter of hole, so compared with the lithium rechargeable battery of embodiment 60 ~ 63,70 ~ 71, the deviation of internal short-circuit fraction defective, discharge capacity slightly raises.
The lithium rechargeable battery of embodiment 76 due to the fiber diameter of used synthetic fibers slightly thick, so compared with the lithium rechargeable battery of embodiment 75, diaphragm strength is slightly weak, and the deviation of discharge capacity slightly raises.
The lithium rechargeable battery of embodiment 78 due to the fiber diameter of used synthetic fibers slightly thin, so compared with the lithium rechargeable battery of embodiment 77, diaphragm strength is slightly weak, and cycle characteristics is slightly poor.
" embodiment 89 ~ 103, comparative example 22 ~ 23 "
< carboxymethyl cellulose (CMC1) >
Be that the carboxymethyl cellulose (the first industrial pharmaceutical society system, trade name: セ ロ ゲ Application (registered trade mark) (CELLOGEN) PL-15) of 0.5 is as CMC1 by degree of etherification falling.
< carboxymethyl cellulose (CMC2) >
Be carboxymethyl cellulose (Co., Ltd.'s Daicel (ダ イ セ Le chemical industry society) system, the trade name: 1205) as CMC2 of 0.7 by degree of etherification falling.
<CDS (cationic starch class paper strengthening agent) >
By cationic starch class paper strengthening agent (starlight PMC society system, trade name: DD4280) as CDS.
<GGS (guar gum paper strengthening agent) >
By guar gum paper strengthening agent (メ イ ホ ー Le ケ ミ カ Le (MeyhallChemical) society system, trade name: メ イ プ ロ イ De (MEYPROID) 2066) as GGS.
[table 13]
In table 13, " kind " of synthetic fibers is as follows:
" PET ": pet fiber.
< dividing plate >
According to raw material as shown in table 13 and blending amount (with whole fibre weight for benchmark), preparation copy paper slurry, uses cylinder paper machine to carry out wet type copy paper, the dividing plate of preparation embodiment 89 ~ 103 and comparative example 22 ~ 23.Thickness is by room temperature carrying out press polish process to adjust.
< lithium rechargeable battery G>
Winding negative pole 1 and positive pole 1, make the dividing plate of embodiment 89 ~ 103 and comparative example 22 ~ 23 respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 150 DEG C of vacuumizes 10 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, the lithium rechargeable battery G of preparation embodiment 89 ~ 103 and comparative example 22 ~ 23.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester (EC) of 30 quality %, the diethyl carbonate (DEC) of 70 quality % makes it reach 1.2M and the electrolyte obtained.
< lithium rechargeable battery H>
According to the order laminating of the dividing plate of embodiment 89 ~ 103 and comparative example 22 ~ 23, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 140 DEG C of vacuumizes 10 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery H (battery capacity=30mAh equivalent).
For dividing plate and the lithium rechargeable battery of embodiment and comparative example, carry out basic weight, thickness, maximum diameter of hole, average pore size, dividing plate moisture content, diaphragm strength, internal resistance, internal short-circuit fraction defective, discharge capacity, the deviation of discharge capacity, the evaluation of capacity dimension holdup, the results are shown in table 14.
[internal resistance]
Under 1C, each 100 chargings of the lithium rechargeable battery G of embodiment and comparative example, after 30 minutes, are measured to internal resistance, calculate each mean value under the interchange of 1kHz.
[internal short-circuit fraction defective]
Use each 100 of the lithium rechargeable battery G of embodiment and comparative example, calculate charging/discharging voltage scope be 2.8 ~ 4.2V, charging and discharging currents determines the internal short-circuit fraction defective of electric 500 circulation times of current charge-discharge repeatedly under being 1C.
[C multiplying power discharging test (discharge capacity)]
Use each 50 of the lithium rechargeable battery H of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), each mean value of discharge capacity when calculating 0.2C and 5C.
[C multiplying power discharging test (deviation of discharge capacity)]
Use each 50 of the lithium rechargeable battery H of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), according to discharge capacity during following standard evaluation 0.2C and 5C.
◎: the difference of discharge capacity is less than 1.0% relative to mean value.
Zero: the difference of discharge capacity relative to mean value more than 1.0% and be less than 2.5%.
△: the difference of discharge capacity relative to mean value more than 2.5% and be less than 5.0%.
×: the difference of discharge capacity relative to mean value more than 5.0%.
[cycle characteristics (the capacity dimension holdup after 100 circulations)]
Use each 20 of the lithium rechargeable battery H of embodiment and comparative example, carry out constant-current constant-voltage charging (1/10C cut-out) under 1C, 4.2V after, under the condition of 1C, carry out constant-current discharge test (2.8V cut-out), calculate the mean value of the capacity dimension holdup after 100 circulations (circulate for 100 times rear/1 circulation volume).
[table 14]
As shown in table 14, the separator for lithium ion secondary battery of embodiment 89 due to the political reform freedom of the 10 quality % containing whole fiber be the synthetic fibers of solvent-spun cellulose fibre, all 90 quality % of fiber of 0ml, and the degree of etherification falling containing 1 quality % is the carboxymethyl cellulose of 0.5, so compared with the embodiment 1 of the table 1 not containing carboxymethyl cellulose, diaphragm strength is excellent.
The separator for lithium ion secondary battery of embodiment 90 due to the political reform freedom of the 50 quality % containing whole fiber be the synthetic fibers of 120ml solvent-spun cellulose fibre, all 50 quality % of fiber, and the degree of etherification falling containing 1 quality % is the carboxymethyl cellulose of 0.5, so maximum diameter of hole diminishes, visible internal resistance and internal short-circuit fraction defective reduce, in addition the deviation of discharge capacity improves, compared with the embodiment 3 of the table 1 not containing carboxymethyl cellulose, diaphragm strength is excellent.
The separator for lithium ion secondary battery of embodiment 91 due to the political reform freedom of the 90 quality % containing whole fiber be the synthetic fibers of solvent-spun cellulose fibre, all 10 quality % of fiber of 250ml, and the degree of etherification falling containing 1 quality % is the carboxymethyl cellulose of 0.5, so aperture same with embodiment 90 and internal resistance improve, compared with the embodiment 3 of the table 1 not containing carboxymethyl cellulose, diaphragm strength is excellent.
The separator for lithium ion secondary battery of embodiment 92 due to the political reform freedom of the 50 quality % containing whole fiber be the synthetic fibers of solvent-spun cellulose fibre, all 50 quality % of fiber of 120ml, and the degree of etherification falling containing 1 quality % is the carboxymethyl cellulose of 0.7, so compared with embodiment 90, aperture and diaphragm strength improve further.In addition, the separator for lithium ion secondary battery of known embodiment 92 due to the degree of etherification falling containing 1 quality % be the carboxymethyl cellulose of 0.7, so with respectively compare known containing the cationic starch class paper strengthening agent of 1 quality % or the embodiment 102 of guar gum paper strengthening agent with the separator for lithium ion secondary battery of embodiment 103, not only diaphragm strength is more excellent, the discharge capacity under high magnification and the deviation of discharge capacity also excellent.
The political reform freedom that the separator for lithium ion secondary battery of embodiment 93 ~ 96 contains 50 quality % of whole fiber is the synthetic fibers of solvent-spun cellulose fibre, all 50 quality % of fiber of 120ml, and be the carboxymethyl cellulose of 0.5 containing degree of etherification falling, dividing plate moisture content, diaphragm strength and battery behavior etc. can be satisfactory.But as embodiment 93, if the content of carboxymethyl cellulose is 0.2 quality % relative to whole fiber quality, then improved texture effect during copy paper is little, there is diaphragm strength and slightly reduces, the trend that aperture also slightly increases.In addition, as embodiment 96, if the content of carboxymethyl cellulose is 3.0 quality % relative to whole fiber quality, then because each dividing plate performance culminates, so be on a sticky wicket in cost, meanwhile, because dehydration property during copy paper is not enough, so be also not satisfied result in production efficiency.
The political reform freedom of 45 ~ 25 quality %s of separator for lithium ion secondary battery containing whole fiber in dividing plate of embodiment 97 ~ 101 is the synthetic fibers of solvent-spun cellulose fibre, all 50 quality % of fiber of 120ml, contain the carboxymethyl cellulose of 1.0 quality % relative to whole fiber quality, the political reform freedom of 5 ~ 25 quality % in addition containing whole fiber is the fibrillation native cellulose fibre of 0 ~ 400ml.Therefore, even if be low basic weight, also high diaphragm strength can be presented, dividing plate can be made thus finer and close and thin, therefore, compared with the separator for lithium ion secondary battery of embodiment 90, the separator for lithium ion secondary battery internal resistance of embodiment 97 ~ 101 is low, and powerful discharge capacity illustrates high numerical value.The lithium rechargeable battery of embodiment 100 due to the political reform freedom in dividing plate be the 20 quality %s of containing ratio more than whole fiber of the fibrillation native cellulose fibre of 0 ~ 400ml, so dividing plate becomes too fine and close slightly, ionic conductivity is slightly deteriorated, compared with the lithium rechargeable battery of embodiment 97 ~ 99, internal resistance illustrates slightly high numerical value, and powerful discharge capacity illustrates lower slightly numerical value.
The political reform freedom of the 40 quality %s of separator for lithium ion secondary battery containing whole fiber in dividing plate of embodiment 101 is the synthetic fibers of solvent-spun cellulose fibre, all 50 quality % of fiber of 120ml, and be the carboxymethyl cellulose of 0.7 relative to the degree of etherification falling that whole fiber quality contains 1.0% quality, the political reform freedom of the 10 quality % in addition containing whole fiber is the fibrillation native cellulose fibre of 270ml.Therefore, compared with embodiment 98, maximum diameter of hole diminishes, and diaphragm strength also increases.
Although the separator for lithium ion secondary battery of comparative example 22 contains carboxymethyl cellulose in dividing plate, but due to the 90 quality %s of containing ratio more than whole fiber that the political reform freedom in dividing plate is the solvent-spun cellulose fibre of 0 ~ 250ml, synthetic fibers are less than 10 quality % of whole fiber, so moisture content is high, diaphragm strength weakens.Although the separator for lithium ion secondary battery of comparative example 23 contains carboxymethyl cellulose in dividing plate, but because the containing ratio that is the solvent-spun cellulose fibre of 0 ~ 250ml of the political reform freedom in dividing plate is less than 10 quality % of whole fiber, synthetic fibers are more than 90 quality % of whole fiber, so maximum diameter of hole becomes large, internal short-circuit fraction defective extremely increases.
" embodiment 104 ~ 126, comparative example 24 ~ 31 "
< heat fusing adhesion fiber M1>
Be 0.5dtex using fiber number, fibre length be the core of 5mm is PETG (fusing point 253 DEG C), sheath portion is that the polyesters core-sheath-type heat fusing adhesion fiber of polyethyleneterephthalate-isophthalic copolymers (softening point 75 DEG C) is as heat fusing adhesion fiber M1.
< heat fusing adhesion fiber M2>
Be 1.1dtex using fiber number, fibre length be the core of 5mm is PETG (fusing point 253 DEG C), sheath portion is that the polyesters core-sheath-type heat fusing adhesion fiber of polyethyleneterephthalate-isophthalic copolymers (softening point 75 DEG C) is as heat fusing adhesion fiber M2.
< heat fusing adhesion fiber M3>
Be 0.8dtex using fiber number, fibre length be the core of 5mm is polypropylene (fusing point 165 DEG C), sheath portion is that the TPO core-sheath-type heat fusing adhesion fiber of high density polyethylene (HDPE) (fusing point 135 DEG C) is as heat fusing adhesion fiber M3.
< heat fusing adhesion fiber M4>
Be 1.1dtex using fiber number, fibre length be the core of 5mm is PETG (fusing point 253 DEG C), sheath portion is that the polyester/ethylene-vinyl alcohol-based core-sheath-type heat fusing adhesion fiber of ethylene-vinyl alcohol copolymer (damp and hot melt temperature 100 DEG C) is as heat fusing adhesion fiber M4.
< heat fusing adhesion fiber M5>
Be 1.1detx using fiber number, fibre length is that the pet fiber that do not stretch (fusing point 130 DEG C) of 5mm is as heat fusing adhesion fiber M5.
< heat fusing adhesion fiber M6>
Be 0.5dtex using fiber number, fibre length is that the pet fiber that do not stretch (hot pressing melt temperature 200 DEG C) of 5mm is as heat fusing adhesion fiber M6.
< heat fusing adhesion fiber M7>
Be 0.8dtex using fiber number, fibre length is that the vinal (damp and hot melt temperature 100 DEG C) of 5mm is as heat fusing adhesion fiber M7.
< heat fusing adhesion fiber M8>
Be 2.2dtex using fiber number, fibre length is that the Splittable conjugate fiber (16 segmentation) formed by polypropylene (fusing point 165 DEG C) and ethylene-vinyl alcohol copolymer (damp and hot melt temperature 100 DEG C) of 5mm is as heat fusing adhesion fiber M8.
According to raw material as shown in Table 15 and content, preparation concentration is 0.1% manufacture paper with pulp and use slurry.
[table 15]
In table 15, " kind " of synthetic fibers, heat fusing adhesion fiber and other fiber is as follows:
" PET ": pet fiber
" AA ": acrylic fiber
" PP ": polypropylene fibre
" PET/PEs-C ": polyesters core-sheath-type heat fusing adhesion fiber
" PP/PE ": TPO core-sheath-type heat fusing adhesion fiber
" PET/EvOH ": polyester/ethylene-vinyl alcohol-based core-sheath-type heat fusing adhesion fiber
" PET-B1 ": the pet fiber that do not stretch (fusing point 130 DEG C)
" PET-B2 ": the pet fiber that do not stretch (hot pressing melt temperature 200 DEG C)
" PVA ": vinal
" PP-EvOH ": polypropylene/ethylene-vinyl alcohol Splittable heat fusing adhesion fiber
" PA ": fibrillation contraposition system Wholly aromatic polyamide fiber.
< dividing plate >
Embodiment 104 ~ 119
Employing utilizes the damp process of cylinder paper machine to copy processing processed and manufactures paper with pulp with slurry 1 ~ 16, make heat fusing adhesion fiber heat bonding, prepare nonwoven fabrics by the cylinder dryers of 140 DEG C.Then, supercalendering process is carried out, as the separator for lithium ion secondary battery of embodiment 104 ~ 119.
Embodiment 120,121
Employing utilizes the damp process of cylinder paper machine to copy processing processed and manufactures paper with pulp with slurry 17,18, make heat fusing adhesion fiber heat bonding, prepare nonwoven fabrics by the cylinder dryers of 140 DEG C.Then, make nonwoven fabrics with the speed of 20m/min and be heated to hot-rolling that the diameter of 200 DEG C is 1.2m and contact and heat-treat.Then, supercalendering process is carried out, as the separator for lithium ion secondary battery of embodiment 120,121.
(embodiment 122 ~ 124, comparative example 24 ~ 29)
Employing utilizes the damp process of cylinder paper machine to copy processing processed and manufactures paper with pulp with slurry 19 ~ 27, make heat fusing adhesion fiber heat bonding, prepare nonwoven fabrics by the cylinder dryers of 140 DEG C.Then, supercalendering process is carried out, as the separator for lithium ion secondary battery of embodiment 122 ~ 124, comparative example 24 ~ 29.
(embodiment 125)
Employing utilizes the damp process of cylinder paper machine to copy processing processed and manufactures paper with pulp with slurry 28, carries out drying, prepare nonwoven fabrics by the cylinder dryers of 140 DEG C.Then, use and be heated to the hot-rolling that the diameter of 200 DEG C is 1.2m, under the speed of the pressure of 2MPa, 10m/min, carry out pressurized heat process, heat fusing is adhered fiber heat bonding, as the separator for lithium ion secondary battery of embodiment 125.
(embodiment 126, comparative example 30,31)
Employing utilizes the damp process of cylinder paper machine to copy processing processed and manufactures paper with pulp with slurry 29 ~ 31, carries out drying, prepare nonwoven fabrics by the cylinder dryers of 140 DEG C.Then, supercalendering process is carried out, as the separator for lithium ion secondary battery of embodiment 126, comparative example 30,31.
< lithium rechargeable battery I>
Winding negative pole 1 and positive pole 1, make the dividing plate of embodiment 104 ~ 126 and comparative example 24 ~ 31 respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 110 DEG C of vacuumizes 24 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, the lithium rechargeable battery I of preparation embodiment 102 ~ 124 and comparative example 24 ~ 31.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
< lithium rechargeable battery J>
According to the order laminating of the dividing plate of embodiment and comparative example, positive pole 2, negative pole 2, wire is led to outside, prepares battery main body part.Then, by battery main body part in 110 DEG C of vacuumizes 15 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery J (battery capacity=30mAh equivalent).
For dividing plate and the lithium rechargeable battery of embodiment and comparative example, carry out the evaluation of basic weight, thickness, maximum diameter of hole, average pore size, dividing plate moisture content, diaphragm strength, internal resistance, internal short-circuit fraction defective, discharge capacity, the deviation of discharge capacity, capacity dimension holdup, voltage sustainment rate, the results are shown in table 16 and table 17.
[table 16]
[internal resistance]
Under 1C, each 100 chargings of the lithium rechargeable battery I of embodiment and comparative example, after 30 minutes, are measured to internal resistance, calculate each mean value under the interchange of 1kHz.
[internal short-circuit fraction defective]
Use each 100 of the lithium rechargeable battery I of embodiment and comparative example, calculate charging/discharging voltage scope be 2.8 ~ 4.2V, charging and discharging currents determines the internal short-circuit fraction defective of electric 500 circulation times of current charge-discharge repeatedly under being 1C.
[C multiplying power discharging test (discharge capacity)]
Use each 50 of the lithium rechargeable battery J of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), each mean value of discharge capacity when calculating 0.2C and 5C.
[C multiplying power discharging test (deviation of discharge capacity)]
Use each 50 of the lithium rechargeable battery J of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), according to discharge capacity during following standard evaluation 0.2C and 5C.
◎: the difference of discharge capacity is less than 1.0% relative to mean value.
Zero: the difference of discharge capacity relative to mean value more than 1.0% and be less than 2.5%.
△: the difference of discharge capacity relative to mean value more than 2.5% and be less than 5.0%.
×: the difference of discharge capacity relative to mean value more than 5.0%.
[cycle characteristics (the capacity dimension holdup after 100 circulations)]
Use lithium rechargeable battery J20 of embodiment and comparative example, carry out constant-current constant-voltage charging (1/10C cut-out) under 1C, 4.2V after, under the condition of 1C, carry out constant-current discharge test (2.8V cut-out), calculate the mean value of the capacity dimension holdup after 100 circulations (circulate for 100 times rear/1 circulation volume).
[voltage sustainment rate]
Use lithium rechargeable battery J50 of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 0.2C, 4.2V, for such lithium rechargeable battery, preserve in the thermostat being set as 60 DEG C after 30 days, measure the voltage of lithium rechargeable battery, calculate the mean value of the voltage sustainment rate before and after preserving.According to following standard evaluation voltage sustainment rate.
Zero: voltage sustainment rate is more than 95%.
△: voltage sustainment rate is less than 95% and be more than 90%.
×: voltage sustainment rate is less than 90%.
[table 17]
Shown in table 16, the separator for lithium ion secondary battery of embodiment 104 ~ 121 due to the political reform freedom containing 10 ~ 90 quality % be the solvent-spun cellulose fibre of 0 ~ 250ml, the synthetic fibers of 10 ~ 90 quality %, so moisture content is low, because the core-sheath-type heat fusing formed containing composition of being adhered by heat fusing adhesion composition and non-heat fusing adheres fiber as at least 1 in synthetic fibers kind, so diaphragm strength is strong, excellent.
That is, the separator for lithium ion secondary battery of embodiment 104 ~ 121 is due to the synthetic fibers containing 10 ~ 90 quality %, so compare with the dividing plate made of paper be made up of with flaxen fiber solvent-spun cellulose fibre of comparative example 31, moisture content can be suppressed in low-level.In addition, owing to being easily wound network of fibers between fiber, by core-sheath-type heat fusing adhesion fiber by its heat bonding securely, so diaphragm strength strengthens.
In addition, relatively more visible by embodiment 110 and 111,112, if use core be PETG, the sheath portion core-sheath-type heat fusing adhesion fiber that is polyester copolymer, then diaphragm strength has the trend of enhancing.The trend that the separator for lithium ion secondary battery vision intensity implementing the embodiment 120 and 121 of Overheating Treatment strengthens further.The separator for lithium ion secondary battery of embodiment 122 ~ 125 owing to using the heat fusing adhesion fiber beyond core-sheath-type, the separator for lithium ion secondary battery of embodiment 124 due to not containing core-sheath-type heat fusing adhesion fiber, so diaphragm strength slightly weakens.
On the other hand, the separator for lithium ion secondary battery of comparative example 24 and 25 due to the political reform freedom in dividing plate be that the containing ratio of the solvent-spun cellulose fibre of 0 ~ 250ml is more than 90 quality %, the synthetic fibers contained in dividing plate are less than 10 quality %, so moisture content is high, diaphragm strength weakens.The separator for lithium ion secondary battery of comparative example 31 is less than 10 quality %, so diaphragm strength weakens due to the containing ratio of the synthetic fibers in dividing plate.
Shown in table 17, the lithium rechargeable battery of embodiment 104 ~ 121 is the solvent-spun cellulose fibre of 0 ~ 250ml, the synthetic fibers of 10 ~ 90 quality % owing to using by the political reform freedom containing 10 ~ 90 quality %, to adhere the dividing plate that fiber formed as the Porous sheet material of at least 1 in synthetic fibers kind containing adhere core-sheath-type heat fusing that composition forms of adhered by heat fusing composition and non-heat fusing, so internal resistance, flash-over characteristic under internal short-circuit fraction defective, particularly high magnification and deviation, cycle characteristics, voltage sustainment rate excellent.
Namely, the lithium rechargeable battery of embodiment 104 ~ 121 due to the political reform freedom that dividing plate contains 10 ~ 90 quality % be the solvent-spun cellulose fibre of 0 ~ 250ml, so guarantor's fluidity of electrolyte is good, ionic conductivity can be made good, therefore, while low internal resistance is shown, the flash-over characteristic particularly under high magnification, cycle characteristics are excellent.On the other hand, the lithium rechargeable battery of comparative example 26 and 27 is less than 10 quality % due to the containing ratio that political reform freedom is the solvent-spun cellulose fibre of 0 ~ 250ml, the lithium rechargeable battery of comparative example 28 is the solvent-spun cellulose fibre of 0 ~ 250ml because dividing plate does not contain political reform freedom, so guarantor's fluidity of electrolyte is poor, internal resistance illustrates high numerical value.
The lithium rechargeable battery of embodiment 104 ~ 121 due to the political reform freedom containing 10 ~ 90 quality % in dividing plate be the solvent-spun cellulose fibre of 0 ~ 250ml, so dividing plate can be made fine and close, therefore the deviation of internal short-circuit fraction defective, discharge capacity is low, excellent.On the other hand, the lithium rechargeable battery of comparative example 26 and 27 is less than 10 quality % due to the containing ratio that the political reform freedom in dividing plate is the solvent-spun cellulose fibre of 0 ~ 250ml, the compactness of dividing plate is not enough, so the deviation of internal short-circuit fraction defective, discharge capacity raises.The lithium rechargeable battery of comparative example 28 is the solvent-spun cellulose fibre of 0 ~ 250ml because dividing plate does not contain political reform freedom, so the compactness of dividing plate is not enough, the deviation of internal short-circuit fraction defective, discharge capacity raises.The lithium rechargeable battery of comparative example 29 is greater than 0 ~ 250ml due to the political reform freedom of the solvent-spun cellulose fibre in dividing plate, and the compactness of dividing plate is not enough, so the deviation of internal short-circuit fraction defective, discharge capacity slightly raises.
The lithium rechargeable battery of embodiment 104 ~ 121 is due to the synthetic fibers containing 10 ~ 90 quality %, as at least 1 in synthetic fibers kind, containing the core-sheath-type heat fusing adhesion fiber that composition of being adhered by heat fusing adhesion composition and non-heat fusing is formed, do not damage the compact texture of network of fibers and make heat bonding between fiber, so while the internal resistance that maintenance is low, illustrate high voltage sustainment rate.On the other hand, the lithium rechargeable battery of embodiment 122 ~ 125 owing to using the heat fusing adhesion fiber beyond core-sheath-type heat fusing adhesion fiber in dividing plate, so when heat bonding heat fusing adhesion fiber form-deprivation, thus local suppresses the Porous of dividing plate, therefore the value of internal resistance is slightly high, and powerful discharge capacity illustrates lower slightly numerical value.The lithium rechargeable battery of embodiment 126 due in dividing plate containing core-sheath-type heat fusing adhesion fiber, so cause voltage sustainment rate that the result of lower slightly numerical value is shown.
" embodiment 127 ~ 132, comparative example 32 ~ 34 "
< fiber A18>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 4mm, is that the solvent-spun cellulose fibre of 125ml is as fiber A18 using political reform freedom.
< fiber A19>
Use fiberizer, process fiber diameter is 10 μm, fibre length is the solvent-spun cellulose fibre of 10mm, is 2.5 μm, fibre length is that the solvent-spun cellulose fibre of 6mm is as fiber A19 using fibre diameter.
< synthetic fibers B9>
Be 2.5 μm using fibre diameter, fibre length is that the pet fiber of 6mm is as synthetic fibers B9.
[table 18]
< dividing plate >
According to raw material shown in table 18 and content, preparation copy paper slurry, uses cylinder paper machine to carry out wet type copy paper, the dividing plate of preparation embodiment 127 ~ 132 and comparative example 32 ~ 34.Thickness is by room temperature carrying out press polish process to adjust.
< lithium rechargeable battery K>
Winding negative pole 1 and positive pole 1, make the dividing plate of embodiment and comparative example respectively between electrode, be accommodated in the cylindrical vessel of aluminum alloy, carry out the welding of wire body.Then, by each cylindrical vessel in 110 DEG C of vacuumizes 15 hours.They let cool in vacuum to room temperature, inject electrolyte, plug is tight, the lithium rechargeable battery K of preparation embodiment and comparative example.Electrolyte uses LiPF 6being dissolved in the mixed solvent be made up of the ethylene carbonate ester of 30 quality %, the diethyl carbonate of 70 quality % makes it reach 1.2M and the electrolyte obtained.
< lithium rechargeable battery L>
According to the order laminating of the dividing plate of embodiment 127 ~ 132 and comparative example 33 ~ 34, positive pole 2, negative pole 2, make A layer become negative side, B layer becomes side of the positive electrode, and wire is led to outside, prepares battery main body part.Then, by battery main body part in 140 DEG C of vacuumizes 10 hours, it is let cool to room temperature in vacuum, insert in the laminated film of aluminium, inject appropriate by 1M-LiPF 6after the electrolyte that/EC+DEC (3:7vol%) is formed carries out vacuum impregnation, remove remaining electrolyte, airtight, prepare lithium rechargeable battery L (battery capacity=30mAh equivalent).
For dividing plate and the lithium rechargeable battery of embodiment and comparative example, carry out basic weight, thickness, maximum diameter of hole, average pore size, dividing plate moisture content, diaphragm strength, internal resistance, internal short-circuit fraction defective, discharge capacity, the deviation of discharge capacity, the evaluation of capacity dimension holdup, the results are shown in table 19.
[internal resistance]
Under 1C, each 100 chargings of the lithium rechargeable battery K of embodiment and comparative example, after 30 minutes, are measured to internal resistance, calculate each mean value under the interchange of 1kHz.
[internal short-circuit fraction defective]
Use each 100 of the lithium rechargeable battery K of embodiment and comparative example, calculate charging/discharging voltage scope be 2.8 ~ 4.2V, charging and discharging currents determines the internal short-circuit fraction defective of electric 500 circulation times of current charge-discharge repeatedly under being 1C.
[C multiplying power discharging test (discharge capacity)]
Use each 50 of the lithium rechargeable battery L of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), each mean value of discharge capacity when calculating 0.2C and 5C.
[C multiplying power discharging test (deviation of discharge capacity)]
Use each 50 of the lithium rechargeable battery L of embodiment and comparative example, carry out under 1C 3 times circulation aging after, constant-current constant-voltage charging (1/10C cut-out) is carried out under 1C, 4.2V, then current value is become 0.2C, 0.5C, 1C, 3C, 5C, carry out constant-current discharge test (2.8V cut-out), according to discharge capacity during following standard evaluation 0.2C and 5C.
◎: the difference of discharge capacity is less than 1.0% relative to mean value.
Zero: the difference of discharge capacity relative to mean value more than 1.0% and be less than 2.5%.
△: the difference of discharge capacity relative to mean value more than 2.5% and be less than 5.0%.
×: the difference of discharge capacity relative to mean value more than 5.0%.
[cycle characteristics (the capacity dimension holdup after 100 circulations)]
Use lithium rechargeable battery L20 of embodiment and comparative example, carry out constant-current constant-voltage charging (1/10C cut-out) under 1C, 4.2V after, under the condition of 1C, carry out constant-current discharge test (2.8V cut-out), calculate the mean value of the capacity dimension holdup after 100 circulations (circulate for 100 times rear/1 circulation volume).
[table 19]
Shown in table 19, if embodiment 127 and embodiment 132 are compared, then the separator for lithium ion secondary battery of embodiment 127 is two-layer structure, political reform freedom due to the 60 quality % containing whole fiber in each layer is the synthetic fibers of solvent-spun cellulose fibre, all 40 quality % of fiber of 125ml, so 5C discharge capacity and capacity dimension holdup excellence.
The separator for lithium ion secondary battery of embodiment 128 is two-layer structure, the political reform freedom containing 6 quality % of whole fiber due to A layer is the synthetic fibers of solvent-spun cellulose fibre, all 40 quality % of fiber of 125ml, the political reform freedom that B layer contains 100 quality % of whole fiber is the solvent-spun cellulose fibre of 125ml, so compared with embodiment 125, although diaphragm strength is slightly poor, but maximum diameter of hole diminishes, internal resistance slightly improves.
The separator for lithium ion secondary battery of embodiment 129 is two-layer structure, the political reform freedom containing 60 quality % of whole fiber due to A layer is the synthetic fibers of solvent-spun cellulose fibre, all 40 quality % of fiber of 125ml, the political reform freedom that B layer contains 90 quality % of whole fiber is the synthetic fibers of solvent-spun cellulose fibre, all 40% quality of fiber of 125ml, so compared with embodiment 125, although diaphragm strength is slightly poor, but maximum diameter of hole diminishes, internal resistance slightly improves.
The separator for lithium ion secondary battery of embodiment 130 is two-layer structure, the political reform freedom containing 60 quality % of whole fiber due to A layer is the synthetic fibers of solvent-spun cellulose fibre, all 40 quality % of fiber of 125ml, the political reform freedom that B layer contains 10 quality % of whole fiber is the synthetic fibers of solvent-spun cellulose fibre, all 90 quality % of fiber of 125ml, so compared with embodiment 125, although diaphragm strength slightly improves, 5C discharge capacity and capacity dimension holdup slightly poor.
The separator for lithium ion secondary battery of embodiment 131 is two-layer structure, the political reform freedom containing 60 quality % of whole fiber due to A layer is the synthetic fibers of solvent-spun cellulose fibre, all 40 quality % of fiber of 125ml, B layer contains the synthetic fibers of 100 quality % of whole fiber, so compared with embodiment 125, although diaphragm strength slightly improves, 5C discharge capacity and capacity dimension holdup slightly poor.
Although the separator for lithium ion secondary battery of comparative example 32 is two-layer structure, but due to the 90 quality %s of containing ratio more than whole fiber that the political reform freedom in dividing plate is the solvent-spun cellulose fibre of 0 ~ 250ml, synthetic fibers are less than 10 quality % of whole fiber, so moisture content is high, diaphragm strength weakens.Although the separator for lithium ion secondary battery of comparative example 33 is two-layer structure, but because the containing ratio that is the solvent-spun cellulose fibre of 0 ~ 250ml of the political reform freedom in dividing plate is less than 10 quality % of whole fiber, synthetic fibers are more than 90 quality % of whole fiber, so maximum diameter of hole becomes large, internal short-circuit fraction defective extremely increases.Although the separator for lithium ion secondary battery of comparative example 34 is two-layer structure, but the solvent-spun cellulose fibre that fibre diameter is 2.5 μm owing to using, fibre length is 6mm, so internal short-circuit fraction defective extremely increases, the discharge capacity under high magnification is non-constant also.
Utilizability in industry
As practical application example of the present invention, separator for lithium ion secondary battery, lithium ion polymer secondary cell dividing plate are suitable.

Claims (43)

1. separator for lithium ion secondary battery, described separator for lithium ion secondary battery by be the solvent-spun cellulose fibre of 0 ~ 250ml containing the political reform freedom of 10 ~ 90 quality %, the Porous sheet material of the synthetic fibers of 10 ~ 90 quality % formed, be that the solvent-spun cellulose fibre of 0 ~ 250ml and synthetic fibers are wound network of fibers mutually by political reform freedom, described political reform freedom except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm are as sieve plate, sample solution concentration is set to beyond 0.1%, measures according to JISP8121.
2. the separator for lithium ion secondary battery of claim 1, wherein, the political reform freedom of solvent-spun cellulose fibre is 0 ~ 200ml.
3. the separator for lithium ion secondary battery of claim 1, wherein, the political reform freedom of solvent-spun cellulose fibre is 0 ~ 160ml.
4. the separator for lithium ion secondary battery any one of claim 1 ~ 3, described separator for lithium ion secondary battery is formed by the Porous sheet material containing the solvent-spun cellulose fibre of 20 ~ 70 quality %, the synthetic fibers of 30 ~ 80 quality %.
5. the separator for lithium ion secondary battery of claim 4, described separator for lithium ion secondary battery is formed by the Porous sheet material containing the solvent-spun cellulose fibre of 30 ~ 60 quality %, the synthetic fibers of 40 ~ 70 quality %.
6. the separator for lithium ion secondary battery any one of claim 1 ~ 3, wherein, the length weighted average fiber length of solvent-spun cellulose fibre is 0.20 ~ 3.00mm.
7. the separator for lithium ion secondary battery of claim 6, wherein, the length weighted average fiber length of solvent-spun cellulose fibre is 0.20 ~ 2.00mm.
8. the separator for lithium ion secondary battery of claim 6, wherein, the length weighted average fiber length of solvent-spun cellulose fibre is 0.20 ~ 1.60mm.
9. the separator for lithium ion secondary battery any one of claim 1 ~ 3, wherein, solvent-spun cellulose fibre has peak frequency peak in its length weighted fibre distribution of lengths histogram between 0.00 ~ 1.00mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 10%.
10. the separator for lithium ion secondary battery of claim 9, wherein, solvent-spun cellulose fibre has peak frequency peak in its length weighted fibre distribution of lengths histogram between 0.30 ~ 0.70mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 12%.
The separator for lithium ion secondary battery of 11. claims 9, wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, the slope with the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm is for more than-3.0 and below-0.5.
The separator for lithium ion secondary battery of 12. claims 11, wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, the slope with the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm is for more than-2.5 and below-0.8.
The separator for lithium ion secondary battery of 13. claims 11, wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, the slope with the ratio of the fiber of the every 0.05mm length weighted fibre length between 1.00 ~ 2.00mm is for more than-2.0 and below-1.0.
Separator for lithium ion secondary battery any one of 14. claims 1 ~ 3, wherein, solvent-spun cellulose fibre has peak frequency peak in its length weighted fibre distribution of lengths histogram between 0.00 ~ 1.00mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 50%.
The separator for lithium ion secondary battery of 15. claims 14, wherein, solvent-spun cellulose fibre has peak frequency peak in its length weighted fibre distribution of lengths histogram between 0.30 ~ 0.70mm, and the ratio with the fiber of more than 1.00mm length weighted fibre length is more than 55%.
The separator for lithium ion secondary battery of 16. claims 14, wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, except peak frequency peak, has peak between 1.50 ~ 3.50mm.
The separator for lithium ion secondary battery of 17. claims 16, wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, except peak frequency peak, has peak between 1.75 ~ 3.25mm.
The separator for lithium ion secondary battery of 18. claims 16, wherein, in the length weighted fibre distribution of lengths histogram of solvent-spun cellulose fibre, except peak frequency peak, has peak between 2.00 ~ 3.00mm.
Separator for lithium ion secondary battery any one of 19. claims 1 ~ 3, wherein, the length weighted average fiber length of solvent-spun cellulose fibre is 0.50 ~ 1.25mm, and Average curl degree is less than 25.
The separator for lithium ion secondary battery of 20. claims 19, wherein, the Average curl degree of solvent-spun cellulose fibre is less than 20.
The separator for lithium ion secondary battery of 21. claims 19, wherein, the Average curl degree of solvent-spun cellulose fibre is less than 15.
Separator for lithium ion secondary battery any one of 22. claims 1 ~ 3, wherein, the political reform freedom of Porous sheet material further containing below 20 quality % is that the fibrillation native cellulose fibre of 0 ~ 400ml forms, described political reform freedom except using that wire diameter is 0.14mm, the aperture 80 order wire nettings that are 0.18mm are as sieve plate, sample solution concentration is set to beyond 0.1%, measures according to JISP8121.
The separator for lithium ion secondary battery of 23. claims 22, its fibrillation native cellulose fibre containing below 10 quality % forms.
The separator for lithium ion secondary battery of 24. claims 22, its fibrillation native cellulose fibre containing below 5 quality % forms.
The separator for lithium ion secondary battery of 25. claims 1, wherein, Porous sheet material forms containing carboxymethyl cellulose further.
The separator for lithium ion secondary battery of 26. claims 1, wherein, Porous sheet material contains the core-sheath-type heat fusing adhesion fiber be made up of heat fusing adhesion composition and non-heat fusing adhesion composition and forms as at least 1 in synthetic fibers kind.
The separator for lithium ion secondary battery of 27. claims 26, wherein, the core of core-sheath-type heat fusing adhesion fiber is PETG, and sheath portion is polyester copolymer.
The separator for lithium ion secondary battery of 28. claims 26 or 27, wherein, Porous sheet material forms through heat treatment.
Separator for lithium ion secondary battery any one of 29. claims 1 ~ 3, wherein, the average pore size of Porous sheet material is more than 0.10 μm, and maximum diameter of hole is less than 6.0 μm.
The separator for lithium ion secondary battery of 30. claims 29, wherein, the average pore size of Porous sheet material is more than 0.10 μm, and maximum diameter of hole is less than 4.0 μm.
The separator for lithium ion secondary battery of 31. claims 29, wherein, the minimum-value aperture of Porous sheet material is more than 0.15 μm, and maximum diameter of hole is less than 3.0 μm.
Separator for lithium ion secondary battery any one of 32. claims 1 ~ 3, wherein, in Porous sheet material, according to the value that the method that specifies in JISB7502 measures, the thickness of the sheet material measured by outside micrometer when namely load is 5N is 6 ~ 50 μm.
The separator for lithium ion secondary battery of 33. claims 32, wherein, in Porous sheet material, according to the value that the method that specifies in JISB7502 measures, the thickness of the sheet material measured by outside micrometer when namely load is 5N is 8 ~ 45 μm.
The separator for lithium ion secondary battery of 34. claims 32, wherein, in Porous sheet material, according to the value that the method that specifies in JISB7502 measures, the thickness of the sheet material measured by outside micrometer when namely load is 5N is 10 ~ 40 μm.
Separator for lithium ion secondary battery any one of 35. claims 1 ~ 3, wherein, the basic weight of Porous sheet material is 5 ~ 40g/m 2.
The separator for lithium ion secondary battery of 36. claims 35, wherein, the basic weight of Porous sheet material is 7 ~ 30g/m 2.
The separator for lithium ion secondary battery of 37. claims 35, wherein, the basic weight of Porous sheet material is 10 ~ 20g/m 2.
Separator for lithium ion secondary battery any one of 38. claims 1 ~ 3, wherein, the synthetic resin forming synthetic fibers is be selected from least a kind in polyester resin, acrylic resin, polyolefin resin.
Separator for lithium ion secondary battery any one of 39. claims 1 ~ 3, wherein, the fiber diameter of synthetic fibers is 0.1 ~ 20 μm.
The separator for lithium ion secondary battery of 40. claims 39, wherein, the fiber diameter of synthetic fibers is 0.1 ~ 15 μm.
The separator for lithium ion secondary battery of 41. claims 39, wherein, the fiber diameter of synthetic fibers is 0.1 ~ 10 μm.
The separator for lithium ion secondary battery of 42. claims 1, wherein, Porous sheet material comprises sandwich construction, and more than two layers is contain the layer of solvent-spun cellulose fibre as required composition that political reform freedom is 0 ~ 250ml.
43. lithium rechargeable batteries, described lithium rechargeable battery uses the separator for lithium ion secondary battery any one of claim 1 ~ 42 to form.
CN201180034584.9A 2010-07-14 2011-07-08 Separator for lithium ion secondary battery and use its lithium rechargeable battery Active CN102986060B (en)

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