CN112510318B - Crosslinked resin dispersion separator - Google Patents

Crosslinked resin dispersion separator Download PDF

Info

Publication number
CN112510318B
CN112510318B CN202010393355.7A CN202010393355A CN112510318B CN 112510318 B CN112510318 B CN 112510318B CN 202010393355 A CN202010393355 A CN 202010393355A CN 112510318 B CN112510318 B CN 112510318B
Authority
CN
China
Prior art keywords
storage device
separator
silane
porous body
steps
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202010393355.7A
Other languages
Chinese (zh)
Other versions
CN112510318A (en
Inventor
张珣
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Asahi Kasei Corp
Original Assignee
Asahi Kasei Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Asahi Kasei Corp filed Critical Asahi Kasei Corp
Publication of CN112510318A publication Critical patent/CN112510318A/en
Application granted granted Critical
Publication of CN112510318B publication Critical patent/CN112510318B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
    • 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
    • H01M50/417—Polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C08J9/40—Impregnation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/54—Silicon-containing compounds
    • C08K5/541—Silicon-containing compounds containing oxygen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/52—Separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2351/00—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
    • C08J2351/06—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2423/04—Homopolymers or copolymers of ethene
    • C08J2423/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2451/00—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
    • C08J2451/06—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/06—Properties of polyethylene
    • C08L2207/068—Ultra high molecular weight polyethylene
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Medicinal Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Materials Engineering (AREA)
  • Power Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Mechanical Engineering (AREA)
  • Cell Separators (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a crosslinked resin dispersion separator. Provided is a separator for an electric storage device, or the like, which can ensure high safety (suppression of the internal maximum heat generation rate and ensuring of the voltage reduction time, which are evaluated by a nail penetration test) by combining the shutdown function and the high-temperature film rupture property. A separator for an electric storage device, wherein the mass ratio of silane-grafted modified polypropylene (A) to polyethylene (B) { (A)/(B) } is 2/98 to 80/20.

Description

Crosslinked resin dispersion separator
Technical Field
The present invention relates to a separator (separator for an electric storage device) or the like obtained by appropriately dispersing silane-grafted modified polypropylene as a crosslinking resin in a predetermined polyethylene.
Background
Microporous membranes are widely used as separation membranes for various substances, permselective separation membranes, separators for separators, etc., and examples of the applications thereof include microfiltration membranes, separators for fuel cells or capacitors, substrates for functional membranes that are filled with functional materials into pores to exert new functions, separators for batteries, etc. Among them, polyolefin microporous films are suitable for use as separators for lithium ion batteries and constituent materials thereof, which are widely used in notebook personal computers, cellular phones, digital cameras, and the like.
In order to ensure battery safety, a separator is required to give consideration to both the start-up of the shutdown (shutdown) function and the increase in the rupture temperature. For example, patent document 1 describes adjusting the high-order physical properties of a polyolefin resin contained in a separator for lithium ion batteries. Patent document 2 describes that the crystallinity and gel fraction region are adjusted to suppress heat generation due to short circuit inside the battery with a shutdown function, and that the performance of preventing rupture of a film (breakdown at 170 ℃ or higher) is ensured even if a high temperature part is locally generated inside the battery cell.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 9-216964
Patent document 2: international publication No. 97/44839
Patent document 3: japanese patent laid-open No. 11-144700
Patent document 4: japanese patent laid-open No. 11-172036
Patent document 5: japanese patent laid-open No. 2001-176884
Patent document 6: japanese patent laid-open No. 2000-319441
Patent document 7: japanese patent application laid-open No. 2017-203145
Disclosure of Invention
Problems to be solved by the invention
In recent years, lithium ion batteries for mobile device mounting or vehicle-mounted use have been increased in output and energy density. Therefore, as the separator to be used, a high-quality product (for example, a small amount of resin aggregates in the separator) is desired. The level of safety of the power storage device is also stricter than ever before, and it is required to have a shutdown function and high-temperature rupture performance higher than those envisaged in patent documents 1 to 7.
In patent document 3, if a master batch catalyst is used in the extrusion step, there is a possibility that the crosslinking reaction of the silane-modified polyethylene proceeds in the extruder, and a resin aggregate is generated in the separator. In addition, in patent document 4, the silane crosslinking reaction may not be sufficiently performed, and it may be difficult to obtain high-temperature rupture resistance.
The heat-resistant resin microporous film described in patent document 7 is obtained by coating a film porous by a dry method with a photopolymerizable coating liquid. In example 5 of patent document 7, a low molecular weight silane coupling agent such as γ -methacryloxypropyl trimethoxysilane is added to the porous membrane. On the other hand, the low-molecular weight silane coupling agent is easily reacted or combined with the plasticizer for making porous in the wet process, and therefore if the low-molecular weight silane coupling agent is used in the wet process, it is expected that the combination of the low-molecular weight silane coupling agent with the resin of the porous film is difficult to occur.
Further, the battery using the separator described in patent documents 3 to 7 has poor cycle characteristics, and there is a concern that the battery safety may be lowered due to the induction of unexpected side reactions in the battery during long-term use.
In view of the above-described problems, an object of the present invention is to provide a separator for an electric storage device that can ensure high safety of the electric storage device (suppression of the internal maximum heat generation rate and ensuring of the voltage reduction time, which are evaluated by a spike test), by combining the shutdown function and the high-temperature film rupture property. Further, the present invention aims to provide a lithium ion secondary battery and an electric storage device including the separator for an electric storage device, and a method for manufacturing the separator for an electric storage device.
Solution for solving the problem
As a result of intensive studies, the present inventors have found that the above problems can be solved by using polyethylene and silane-grafted modified polypropylene as a crosslinking resin in a predetermined ratio, and have completed the present invention. Namely, the present invention is as follows.
[1]
A separator for an electric storage device, wherein the mass ratio of silane-grafted modified polypropylene (A) to polyethylene (B) { (A)/(B) } is 2/98 to 80/20.
[2]
The separator for an electric storage device according to item 1, wherein the rupture temperature measured by thermo-mechanical analysis (TMA) is 170 to 210 ℃.
[3]
A method for manufacturing a separator for an electric storage device,
the method comprises the following steps:
(1) A sheet molding step of extruding the silane-grafted modified polypropylene (A), the ultra-high molecular weight polyethylene (B), and the plasticizer, cooling and solidifying the extruded materials, and molding the extruded materials into a sheet having a mass ratio ((A)/(B)) of 1/99 to 80/20;
(2) A stretching step of stretching the sheet to obtain a stretched product;
(3) A porous body forming step of extracting a plasticizer from the stretched product to form a porous body; the method comprises the steps of,
(4) And a heat treatment step of heat-treating the porous body to obtain a heat-treated porous body.
[4]
According to the method for manufacturing a separator for an electrical storage device of claim 3,
the method also comprises the following steps:
(5) An affinity treatment step of immersing the heat-treated porous body in an organic solvent having amphiphilicity to water and an organic substance to obtain an affinity-treated porous body;
(6) A crosslinking treatment step of bringing the affinity-treated porous body into contact with a mixture containing an organometallic catalyst and water, or immersing the affinity-treated porous body in an alkali solution or an acid solution to form a crosslinked porous body having a silane crosslinked structure; the method comprises the steps of,
(7) And a water washing and drying step of washing and drying the crosslinked porous body.
[5]
A method of manufacturing an electrical storage device,
which comprises the following steps of;
(2-I) a preparation step of preparing an outer case of a laminate or a wound body containing the electrode and the separator for an electric storage device according to claim 1 or 2, and a nonaqueous electrolytic solution; the method comprises the steps of,
(2-II) a liquid injection step of injecting the nonaqueous electrolytic solution into the outer case.
[6]
The method for manufacturing an electric storage device according to claim 5, wherein the silane crosslinking reaction of the silane-grafted modified polyolefin contained in the separator for an electric storage device is started by bringing the separator for an electric storage device into contact with the nonaqueous electrolyte during or after the liquid injection step.
[7]
The method for manufacturing an electrical storage device according to claim 5 or 6, wherein the nonaqueous electrolyte solution contains a fluorine-containing lithium salt.
[8]
The method for manufacturing an electrical storage device according to any one of claims 5 to 7, wherein the nonaqueous electrolyte is an acid solution or an alkali solution.
[9]
The method for manufacturing an electrical storage device according to any one of claim 5 to 8,
the method also comprises the following steps:
(2-III) a terminal connection step of connecting a lead terminal to the electrode in the outer case or the electrode exposed from the outer case; the method comprises the steps of,
(2-IV) a charge/discharge step of performing charge/discharge for at least 1 cycle.
[10]
A lithium ion secondary battery comprising a positive electrode, a negative electrode, the separator for an electrical storage device according to item 1 or 2, and a nonaqueous electrolytic solution.
[11]
An electric storage device comprising a positive electrode, a negative electrode, the separator for an electric storage device according to claim 1 or 2, and a nonaqueous electrolytic solution.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, by combining the shutdown function and the high-temperature rupture resistance of the separator for the power storage device, it is possible to provide the separator for the power storage device that can ensure high safety of the power storage device (suppression of the internal maximum heat generation rate and ensuring of the voltage reduction time, which are evaluated by the spike test). Further, according to the present invention, a lithium ion secondary battery and an electric storage device including the separator for an electric storage device, and a method for manufacturing the separator for an electric storage device can be provided.
Detailed Description
Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described, but the present invention is not limited to this embodiment only. The present invention may be variously modified within a range not departing from the gist thereof. In the present specification, "to" means that the numerical values at both ends thereof are included as the upper limit value and the lower limit value unless otherwise specified. In this specification, the upper limit value and the lower limit value of the numerical range may be arbitrarily combined.
< electric storage device >
The separator for an electric storage device (hereinafter, sometimes simply referred to as "separator") of the present embodiment is used for an electric storage device. The power storage device includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolytic solution. Examples of such a power storage device include: lithium batteries, lithium secondary batteries, lithium ion secondary batteries, sodium ion secondary batteries, magnesium ion secondary batteries, calcium ion secondary batteries, aluminum ion secondary batteries, nickel-hydrogen batteries, nickel-cadmium batteries, electric double layer capacitors, lithium ion capacitors, redox flow batteries, lithium sulfur batteries, lithium air batteries, zinc air batteries, and the like. Among them, from the viewpoint of practical use, lithium batteries, lithium secondary batteries, lithium ion secondary batteries, nickel hydrogen batteries, and lithium ion capacitors are preferable, and lithium batteries and lithium ion secondary batteries are more preferable.
< lithium ion Secondary Battery >
The lithium ion secondary battery is, for example, the following battery: lithium transition metal oxides such as lithium cobalt oxide and lithium cobalt composite oxides are used as the positive electrode, carbon materials such as graphite and black lead are used as the negative electrode, and nonaqueous electrolytic solutions are used.
Examples of the nonaqueous solvent constituting the nonaqueous electrolytic solution include: ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate or a mixed solvent thereof, and the like. Examples of the electrolyte constituting the nonaqueous electrolyte solution include: fluorine-containing lithium salt (LiPF) 6 、LiBF 4 、LiN(SO 2 CF 3 ) 2 、LiSO 3 CF 3 Etc.) or LiBC 4 O 8 Etc. A separator is disposed between the electrodes so that lithium (Li) can move between the electrodes and contact between the electrodes can be avoided.
< separator >
(polyolefin microporous film)
The separator of the present embodiment includes the polyolefin microporous membrane of the present embodiment (hereinafter, sometimes simply referred to as "microporous membrane").
The microporous membrane comprises (A) a silane grafted modified polypropylene and (B) a polyethylene. And the mass ratio of the silane-grafted modified polypropylene to the polyethylene { (A)/(B) } is 2/98 to 80/20. In other words, the mass ratio of the silane-grafted modified polypropylene is 2 to 80 mass% and the mass ratio of the polyethylene is 20 to 98 mass% based on 100% of the total mass of the silane-grafted modified polypropylene and the polyethylene. In this way, a separator of high quality (for example, a separator in which resin aggregates are less) can be realized, and by including such a separator, high safety of the power storage device (suppression of the internal maximum heat generation rate and assurance of the voltage reduction time, which are evaluated by the nail penetration test) can be ensured.
In this regard, in the microporous membrane, the silane-grafted polypropylene has a silane crosslinked structure (gelled structure), and thus can exhibit high-temperature rupture resistance. This is presumably because the polypropylene dispersed in the polyethylene is suitably connected by a silane crosslinked structure, and as a result, the morphology of the whole film changes, and even if the melting point of the polyethylene is exceeded (for example, about 130 to 140 ℃) and the melting point of the polypropylene is in the vicinity of or exceeds the melting point (for example, about 170 ℃), the film shape can be maintained. Therefore, from the viewpoint of securing high-temperature film breakage resistance, the mass ratio of the silane-grafted modified polypropylene is preferably 2.5 mass% or more, more preferably 3 mass% or more, based on 100% by mass of the total mass of the silane-grafted modified polypropylene and the polyethylene. In other words, the mass ratio of the polyethylene is preferably 97.5 mass% or less, more preferably 97 mass% or less.
On the other hand, when the microporous membrane contains polyethylene, the microporous membrane can be heat-set at a high temperature while suppressing clogging of pores of the obtained microporous membrane. Therefore, from the viewpoint of forming a dense and uniform porous structure, the mass ratio of polyethylene is preferably 20.5 mass% or more, more preferably 21 mass% or more, based on 100% by mass of the total mass of silane-grafted modified polypropylene and polyethylene. In other words, the mass ratio of the silane-grafted modified polypropylene is preferably 98.5 mass% or less, more preferably 98 mass% or less.
The weight average molecular weight of the whole microporous membrane is preferably 100,000 or more and 1,200,000 or less, more preferably 150,000 or more and 800,000 or less.
The total mass of the silane-grafted polypropylene and the polyethylene is preferably 50 mass% or more, more preferably 65 mass% or more, still more preferably 80 mass% or more, and particularly preferably 95 mass% or more, based on 100 mass% of the total of the microporous film, from the viewpoint of reliably exerting the operational effects of the present invention.
The microporous membrane may contain an organometallic-containing catalyst (dehydration condensation catalyst); a plasticizer; metal soaps such as calcium stearate and zinc stearate; an ultraviolet absorber; a light stabilizer; an antistatic agent; an antifogging agent; a coloring pigment; and the like.
((A) silane grafted modified Polypropylene)
The silane-grafted modified polypropylene is composed of a main chain of polyolefin and an alkoxysilyl group grafted to the main chain. It is presumed that the alkoxysilyl group is converted into a silanol group by a hydrolysis reaction based on water, and a crosslinking reaction occurs to form a siloxane bond (see the following formula; the ratio of the structure change from the T0 structure to the T1 structure, the T2 structure or the T3 structure is arbitrary). The alkoxide substituted with an alkoxysilyl group includes: methoxide, ethoxide, butoxide, and the like. For example, in the following formula, R may be: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, and the like.
In silane grafted modified polypropylene, the backbone is covalently linked to the grafts. The structure for forming the covalent bond is not particularly limited, and examples thereof include an alkyl group, an ether, a glycol, and an ester. The silicon-grafted polypropylene preferably has a silicon to carbon ratio (Si/C) of 0.2 to 1.8%, more preferably 0.5 to 1.7%, at the stage before the crosslinking reaction.
The density of the preferable silane grafted modified polypropylene is 0.82-0.96 g/cm 3 And a Melt Flow Rate (MFR) at 230 ℃ of 0.5 to 25g/min.
The polypropylene constituting the silane-grafted modified polypropylene may be composed of 1 kind of propylene alone or 2 or more kinds of propylene. More than 2 kinds of silane-grafted modified polypropylene composed of different propenes may be used in combination.
Further, as the polypropylene constituting the silane-grafted modified polypropylene, a homopolymer of propylene is preferable.
In view of the process for producing a separator according to the present embodiment, the silane-grafted modified polypropylene has a silanol-containing unit content of 10% or less, preferably 5% or less, and more preferably 2% or less, based on the modified amount of all ethylene units in the main chain, at a stage before the crosslinking treatment step described later. The density of the preferable silane grafted modified polypropylene is 0.90-0.96 g/cm 3 And a Melt Flow Rate (MFR) at 190 ℃ of 0.2 to 5 g/min.
The crosslinking reaction is promoted using an organometallic-containing catalyst. In the present specification, a material obtained by adding an organometallic catalyst to a resin containing silane-grafted modified polypropylene in advance before a sheet forming step (for example, a kneading step performed as needed) is referred to as a masterbatch resin.
((B) polyethylene)
As the polyethylene, 1 kind of polyethylene alone may be used, or 2 or more kinds of polyethylene may be used in combination.
As polyethylene, a homopolymer of ethylene is preferable. However, if 50 mass% or less or 45 mass% or less with respect to the total mass of ethylene constituting the polyethylene, a monomer other than ethylene (other monomer) may be contained. Examples of the other monomer include: propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, norbornene and the like.
(optional layer)
The microporous membrane may be used as a separator itself, or a microporous membrane having a functional layer on at least one side thereof may be used as a separator. Examples of the functional layer include an inorganic porous layer containing inorganic particles and a binder, an adhesive layer containing a thermoplastic polymer, and the like, but are not limited thereto.
< thermo-mechanical analysis (TMA) >)
From the viewpoint of reliably ensuring the high-temperature rupture resistance of the separator and reliably ensuring the safety of the power storage device, the rupture temperature of the separator measured by TMA is preferably 170 to 210 ℃. As described above, in the present embodiment, the silane-crosslinked polypropylene is suitably dispersed in the polyethylene, and as a result, the morphology of the entire film is changed, and the film shape can be maintained even at a temperature near or exceeding the melting point of the polyethylene (170 to 210 ℃).
In general, even when the power storage device generates heat due to an unexpected runaway reaction, the separator melts (fuse) at a low temperature (for example, 150 ℃ or lower), and the movement of Li ions is stopped early, and the discharge inside or outside the power storage device accompanies the movement. Then, the entire power storage device is cooled by natural cooling by the outside air or the refrigerant of the power storage device, whereby it is expected to prevent ignition of the nonaqueous electrolytic solution or decomposition and heat generation reaction of the electrolyte, and safety is ensured. However, even if the runaway reaction occurring in the power storage device is not stopped by melting, but continues to generate heat, the separator of the present embodiment can suppress melting rupture at a high temperature of 170 to 210 ℃.
The membrane rupture temperature measured by TMA can be obtained by the method described in the examples, and can be controlled by changing the composition of the microporous membrane.
< Property of separator >
Hereinafter, although the characteristics of the microporous membrane are described, in the case where the microporous membrane itself is used as a separator, the characteristics of the microporous membrane can be interpreted as the characteristics of the separator.
The porosity of the microporous membrane is preferably 20% or more, more preferably 30% or more, and further preferably 32% or more or 35% or more. When the porosity is 20% or more, the following property to rapid movement of lithium (Li) ions tends to be further improved. On the other hand, the porosity is preferably 90% or less, more preferably 80% or less, and still more preferably 50% or less. When the porosity is 90% or less, the film strength tends to be further improved, and self-discharge tends to be further suppressed. The porosity can be measured by the method described in the examples, and can be controlled by changing the stretching ratio of the microporous membrane.
The air permeability of the microporous membrane is preferably 1sec/100cm 3 The above is more preferably 50sec/100cm 3 The above is more preferably 55sec/100cm 3 The above is more preferably 70sec/100cm 3 Above, 90sec/100cm 3 The above. By making the air permeability 1sec/100cm 3 As described above, the balance between the film thickness and the porosity and the average pore diameter tends to be further improved. Further, the air permeability is preferably 400sec/100cm 3 Hereinafter, it is more preferably 300sec/100cm 3 Hereinafter, 270sec/100cm is more preferable 3 The following is given. By making the air permeability 400sec/100cm 3 Hereinafter, the ion permeability tends to be further improved. The air permeability can be measured by the method described in the examples, and can be controlled by changing the stretching temperature and/or the stretching ratio of the microporous film.
The film thickness of the microporous film is preferably 1.0 μm or more, more preferably 2.0 μm or more, still more preferably 3.0 μm or more, 4.0 μm or more, or 4.5 μm or more. When the film thickness is 1.0 μm or more, the film strength tends to be further improved. On the other hand, the film thickness is preferably 500 μm or less, more preferably 100 μm or less, further preferably 80 μm or less, 22 μm or less, or 19 μm or less. When the film thickness is 500 μm or less, ion permeability tends to be further improved. The film thickness can be measured by the method described in the examples, and can be controlled by changing the stretching ratio of the microporous film.
When a microporous film is used as a separator for a lithium ion secondary battery or a constituent material thereof, the film thickness of the microporous film is preferably 25 μm or less, more preferably 22 μm or less or 20 μm or less, further preferably 18 μm or less, particularly preferably 16 μm or less. When the film thickness is 25 μm or less, permeability tends to be further improved. In this case, the lower limit of the film thickness may be 1.0 μm or more, 3.0 μm or more, 3.5 μm or more, or 4.0 μm or more.
< method for producing separator >
The method for manufacturing the separator comprises the following steps:
(1) A sheet forming step;
(2) A stretching step;
(3) A porous body forming step; the method comprises the steps of,
(4) And (3) a heat treatment process.
The method for producing the separator may include a kneading step before the sheet forming step (1) and/or a winding step after the heat treatment step (4), as desired.
(kneading step)
The kneading step is a step of kneading a polyolefin composition comprising silane-grafted modified polypropylene and ultrahigh molecular weight polyethylene (UHMWPE: ultra High Molecular Weight Poly Ethylene) to obtain a kneaded product. The polyolefin composition may comprise an organometallic-containing catalyst; a plasticizer; metal soaps such as calcium stearate and zinc stearate; an ultraviolet absorber; a light stabilizer; an antistatic agent; an antifogging agent; a coloring pigment; and the like.
(1) sheet Forming step (extrusion step)
The sheet molding step is a step of extruding a mixture of the obtained kneaded product and a plasticizer (i.e., a mixture of silane-grafted modified polypropylene, UHMWPE, and a plasticizer), cooling, solidifying, and molding into a sheet. The extrusion of the mixture may use a known extruder. The molding method is not particularly limited, and examples thereof include a method of solidifying a melt obtained by melt kneading and extrusion by compression cooling. The cooling method includes: a method of directly contacting a cooling medium such as cold air or cooling water, a method of contacting a roll or a press cooled with a refrigerant, and the like. Among them, the method of contacting the roller or the press cooled with the refrigerant is preferable in view of excellent film thickness controllability.
The mass ratio of (A) silane grafted modified polypropylene to (B) UHMWPE in the sheet is 2/98-80/20. In this way, a separator of high quality (for example, a separator in which resin aggregates are less) can be realized, and by including such a separator, high safety of the power storage device (suppression of the internal maximum heat generation rate and assurance of the voltage reduction time, which are evaluated by the nail penetration test) can be ensured.
Herein, UHMWPE refers to polyethylene having a weight average molecular weight of 100,000 or more. More than 2 kinds of UHMWPE having different weight average molecular weights may be used in combination.
As UHMWPE, a homopolymer of ethylene is preferred. However, if 50 mass% or less or 45 mass% or less with respect to the total mass of ethylene constituting the UHMWPE, a monomer other than ethylene (other monomer) may be contained. Examples of the other monomer include: propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, norbornene and the like.
The silane-grafted modified polypropylene is preferably not a masterbatch resin in the sheet forming step from the viewpoint of ensuring low-temperature shutdown properties at 150 ℃ or less, suppressing thermal runaway at the time of failure of the power storage device while having film breakage resistance at 170 to 210 ℃ to improve safety.
The plasticizer is not particularly limited, and examples thereof include organic compounds which can form a uniform solution with polyolefin at a temperature of not more than the boiling point. More specifically, there can be mentioned: decalin, xylene, dioctyl phthalate, dibutyl phthalate, stearyl alcohol, oleyl alcohol, decyl alcohol, nonanol, diphenyl ether, n-decane, n-dodecane, paraffin oil, etc. Of these, paraffin oil and dioctyl phthalate are preferable. The plasticizer may be used alone or in combination of 1 or more than 2. The proportion of the plasticizer is not particularly limited, but is preferably 20 mass% or more in terms of the porosity of the resulting microporous film, and is preferably 90 mass% or less in terms of the viscosity at the time of melt kneading, relative to 100 mass% of the sum of the silane-grafted modified polypropylene and the UHMWPE.
((2) stretching step)
The stretching step is a step of stretching the sheet obtained in the sheet forming step to obtain a stretched product. The sheet stretching method includes: MD uniaxial stretching by a roller stretcher, TD uniaxial stretching by a stenter, sequential biaxial stretching by a combination of a roller stretcher and a stenter or a stenter and a stenter, simultaneous biaxial stretching by a simultaneous biaxial stenter or inflation forming, and the like. From the viewpoint of obtaining a more uniform film, simultaneous biaxial stretching is preferable. MD refers to the machine direction of the film, and TD refers to the width direction, i.e., the direction perpendicular to the MD.
The total surface magnification is preferably 8 times or more, more preferably 15 times or more, and even more preferably 20 times or more or 30 times or more, from the viewpoint of uniformity of film thickness, tensile elongation, and balance of porosity and average pore diameter. When the total surface magnification is 8 times or more, a sheet having high strength and good thickness distribution tends to be easily obtained. The surface magnification may be 250 times or less from the viewpoint of preventing breakage or the like.
((3) porous body Forming step (extraction step))
The porous body forming step is a step of extracting a plasticizer from the stretched product obtained in the stretching step to form a porous body. The extraction method of the plasticizer is not particularly limited, and examples thereof include: a method of immersing the stretched product in the extraction solvent, a method of spraying the extraction solvent on the stretched product, and the like. The extraction solvent is not particularly limited, and is preferably, for example, a poor solvent for polyolefin and a good solvent for plasticizer, and a solvent having a boiling point lower than the melting point of polyolefin. The extraction solvent is not particularly limited, and examples thereof include: hydrocarbons such as n-hexane and cyclohexane; halogenated hydrocarbons such as methylene chloride, 1-trichloroethane and fluorocarbons; alcohols such as ethanol and isopropanol; ketones such as acetone and 2-butanone; alkaline water, and the like. The extraction solvent may be used alone or in combination of 1 or more than 2.
((4) Heat treatment step)
The heat treatment step is a step of heat-treating the porous body obtained in the porous body formation step to obtain a heat-treated porous body. The heat treatment method is not particularly limited, and examples thereof include a heat setting method in which stretching and relaxation operations are performed by a stenter or a roll stretcher. The relaxation operation refers to a shrinking operation performed at a prescribed temperature and relaxation rate along the MD and/or TD of the film. The relaxation rate is a value obtained by dividing the MD size of the film after the relaxation operation by the MD size of the film before the operation; or a value obtained by dividing the TD size after the relaxation operation by the TD size of the film before the operation; or when both MD and TD are relaxed, the value obtained by multiplying the relaxation rate of MD by the relaxation rate of TD is referred to.
In the production method 1, it is preferable to stretch and relax the porous body in the TD of the porous body from the viewpoint of obtaining a heat-treated porous body suitable for the subsequent affinity treatment step and crosslinking treatment step.
< method for producing 1 >
Hereinafter, a 1 st manufacturing method for manufacturing the power storage device will be described.
First, the method for manufacturing the separator used in the power storage device preferably further includes the following steps in addition to the steps (1) to (4):
(5) An affinity processing step;
(6) A crosslinking treatment step; the method comprises the steps of,
(7) A water washing and drying process, wherein in the water washing and drying process,
if desired, a winding process may be included after the process (7).
((5) affinity treatment step)
The affinity treatment step is a step of immersing the heat-treated porous body obtained in the heat treatment step in an organic solvent having amphiphilicity to water and an organic substance to obtain an affinity-treated porous body. Specifically, the method is a step of immersing the heat-treated porous body in an organic solvent having amphipathy to water and organic substances to obtain an affinity-treated porous body in order to improve wettability between water and polyolefin. In this embodiment, since the organic solvent having amphipathy is disposed inside the affinity-treated porous body (affinity-treated porous body), affinity with the liquid can be increased. In this way, for example, in the crosslinking treatment step, the affinity with a material or a catalyst that promotes the crosslinking reaction may be increased. The organic solvent to be used is not particularly limited, and examples thereof include: alcohols, acetone, ethylene carbonate, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and the like. The method of impregnation is not particularly limited, and examples thereof include: a method of immersing the heat-treated porous body in an organic solvent, a method of spraying the heat-treated porous body with an organic solvent, and the like.
((6) crosslinking treatment step)
The crosslinking treatment step is a step of bringing the affinity-treated porous body obtained in the affinity treatment step into contact with a mixture containing an organometallic catalyst and water, or immersing the affinity-treated porous body in an alkali solution or an acid solution, thereby forming a crosslinked porous body having a silane crosslinked structure. That is, the crosslinking treatment step is a step of subjecting the alkoxysilyl groups contained in the obtained affinity-treated porous body to a silane dehydration condensation reaction (crosslinking reaction) to form siloxane bonds.
In many cases, a conventional molded article such as a hot water pipe is fed with a Sn-based catalyst in an extruder during an extrusion step. However, in the process for producing a separator for an electric storage device, if silane crosslinking is promoted in an extruder in a sheet forming step, a gelled portion may cause production failure, and it is difficult to stretch a silane-crosslinked polyolefin in a subsequent stretching step. Therefore, in the production method 1, the silane crosslinking treatment is performed after the stretching step, the heat treatment step, and the affinity treatment step. The silane crosslinked portion thus obtained ensures heat resistance, shape retention and film breakage resistance of the separator.
The metal containing the organometallic catalyst may be, for example, at least 1 selected from the group consisting of scandium, vanadium, copper, zinc, zirconium, palladium, gallium, tin, titanium, iron, nickel, and lead, and among them, tin, zinc, or palladium is preferable, and tin or zinc is more preferable. Examples of the organotin complex that can be used as the catalyst include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, and the like.
The alkali solution has a pH exceeding 7 and may contain, for example, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkali metal phosphates, ammonia, amine compounds, and the like. Among these, alkali metal hydroxides or alkaline earth metal hydroxides are preferable from the viewpoints of safety of the power storage device and silane crosslinkability, alkali metal hydroxides are more preferable, and sodium hydroxide is further preferable.
The acid solution has a pH of less than 7 and may comprise, for example, inorganic acids, organic acids, and the like. Preferred acids are hydrochloric acid, sulfuric acid, carboxylic acids or phosphoric acids.
The crosslinking treatment step is preferably performed by immersing the affinity-treated porous body in an alkali solution or an acid solution, in order to suppress a thermal runaway reaction at the time of destruction of the power storage device and to improve safety.
In the case of immersing the affinity-treated porous body in an alkaline solution, the temperature of the alkaline solution is preferably 20 to 100℃and/or the pH of the alkaline solution is preferably 8 to 14, from the viewpoint of further improving the safety. The reagent used for pH adjustment is not particularly limited, and examples thereof include alkali metal hydroxides and alkaline earth metal hydroxides. From the same point of view, the aqueous alkali preferably does not contain amine compounds such as ethylamine, dibutylamine, hexylamine, pyridine, and the like.
In the case of immersing the affinity-treated porous body in an acid solution, although it is not desirable to carry out a constraint in theory, it is presumed that the acid exerts a catalytic action that promotes formation of si—o bonds of the silane-crosslinked polyolefin, rather than cleaving si—o bonds of the silane-crosslinked polyolefin.
In the case of bringing the affinity-treated porous body into contact with a mixture containing an organometallic catalyst and water, the content of scandium, vanadium, copper, zinc, zirconium, palladium, gallium, tin, titanium, iron, nickel or lead in the final microporous membrane is preferably adjusted to a range of 0.10ppm to 200ppm in terms of total amount in terms of atoms, from the viewpoint of controlling the amorphous portion of the affinity-treated porous body and securing safety. In particular, the zinc or tin content of the microporous membrane is more preferably adjusted to a range of 0.10ppm to 200ppm in terms of total amount in atomic terms. The scandium, vanadium, copper, zinc, zirconium, palladium, gallium, tin, titanium, iron, nickel, or lead content of the microporous membrane can be adjusted by, for example, a water washing and drying step described later. With such a metal-containing amount in the limited range, decomposition of the crosslinked structure of the film can be suppressed, whereby safety is easily ensured and the battery cycle characteristics tend to exhibit good performance. If the metal is excessively contained in the separator, there is a possibility that eluted ions may intrude into the positive electrode, and the structure of the Li-stored metal cluster may be changed, so that an electrical defect point may be generated in the positive electrode as a whole, and the cycle performance may be deteriorated.
((7) Water washing drying Process)
The water-washing and drying step is a step of washing and drying the crosslinked porous body obtained in the crosslinking step. The preferable conditions of the washing and drying step are a water temperature of 20 to 100℃and/or a pH of 6 to 8. For example, the inside of the crosslinked porous body may be replaced with water having a pH of 6 to 8 at a temperature of 20 to 100℃and then dried. The drying method is not particularly limited, and examples thereof include conveying with a heating roller, blowing hot air, and drying by heating with an infrared heater. The microporous membrane can be obtained by a water washing and drying process.
(winding step)
The winding step is a step of slitting and winding the microporous membrane obtained in the above-described washing and drying step on a predetermined core as needed. As described above, the microporous film may be used as a separator by itself, or may be used as a separator having a functional layer on at least one side thereof.
When the winding step is performed after the heat treatment step, the winding step is regarded as a step of cutting and winding the heat-treated porous body obtained in the heat treatment step, if necessary, onto a predetermined core.
The method for manufacturing the power storage device using the separator may include, for example, the following steps;
(1-I) a step of laminating and/or winding the positive electrode, the separator obtained in the 1 st production method, and the negative electrode to obtain a laminate or a wound body;
(1-II) a step of incorporating the laminate or the wound body into an outer case;
(1-III) a step of injecting a nonaqueous electrolytic solution into the outer case; the method comprises the steps of,
(1-IV) connecting lead terminals to the positive electrode and the negative electrode.
The steps (1-I) to (1-IV) may be performed by a method known in the art, except that the separator is used. The above-described electrode and nonaqueous electrolyte solution may be used in the steps (1-I) to (1-IV), and positive electrode, negative electrode, nonaqueous electrolyte solution, outer case and charge/discharge device known in the art may be used.
< method for producing 2 >
Hereinafter, a 2 nd manufacturing method for manufacturing the power storage device will be described.
First, in the production method 2, the heat-treated porous body obtained through the steps (1) to (4) may be prepared and used as a separator.
The method for manufacturing the power storage device using the separator includes the following steps;
(2-I) a preparation step of preparing an outer case of a laminate or a wound body containing an electrode and a separator, and a nonaqueous electrolytic solution;
(2-II) a liquid injection step of injecting a nonaqueous electrolyte into the outer casing;
(2-III) a terminal connection step of connecting lead terminals to the electrodes in the outer case or the electrodes exposed from the outer case, as desired; the method comprises the steps of,
(2-IV) a charging/discharging step, as desired, of at least 1 cycle.
The steps (2-I) to (2-IV) may be performed by a method known in the art, except that a separator (the heat-treated porous body obtained through the steps (1) to (4)) is used. In the steps (2-I) to (2-IV), the above-described electrode and nonaqueous electrolyte solution may be used, and a positive electrode, a negative electrode, a nonaqueous electrolyte solution, an outer case, and a charge/discharge device known in the art may be used.
In the 2 nd production method, the separator is preferably brought into contact with a nonaqueous electrolyte in the step (2-II) or after the step (2-II), and the silane crosslinking reaction of the silane-grafted modified polypropylene is started. In addition, from the viewpoint of reliably carrying out the silane crosslinking reaction of the separator, the steps (2-III) and (2-IV) are preferably carried out. It is considered that the silane crosslinking reaction is effected by causing a substance that catalyzes the silane crosslinking reaction to be generated in the nonaqueous electrolytic solution or on the surface of the electrode by charge-discharge cycles.
Although not wishing to be bound by theory, it is assumed that the silane grafting portion is converted into silanol by a minute amount of moisture (moisture contained in an electrode, a separator, an electrolyte, or the like) contained in the power storage device, and a crosslinking reaction proceeds to change into siloxane bond. Further, it is considered that, when the nonaqueous electrolytic solution (or the electrolyte in the nonaqueous electrolytic solution) is brought into contact with the electrode, that is, substances which catalyze the silane crosslinking reaction are generated in the nonaqueous electrolytic solution or on the surface of the electrode, they dissolve in the nonaqueous electrolytic solution, uniformly swell and diffuse into amorphous portions in the polyolefin in which the silane grafted portions exist, and thus uniformly promote the crosslinking reaction of the separator-containing laminate or the wound body. The material that catalyzes the silane crosslinking reaction may be an acid solution (e.g., pH<7 inorganic or organic acid, etc.), alkali solution (e.g., pH>7, etc.) or film form, the electrolyte contains LiPF 6 In the case of (C) may be a material consisting of LiPF 6 Hydrogen Fluoride (HF) generated by reaction with moisture or fluorine-containing organic matter derived from HF. Here, HF or a fluorine-containing organic corresponds to the chemical substance generated in the battery of the present embodiment.
As the nonaqueous electrolyte, the above-mentioned substances can be used as the nonaqueous electrolyte usable for the lithium ion secondary battery, and LiPF is preferable from the viewpoint of promoting the crosslinking reaction of the separator, for example 6 、LiN(SO 2 CF 3 ) 2 Or LiSO 3 CF 3 。
By using the separator (the heat-treated porous body obtained through the steps (1) to (4)) above, it is possible to provide an electricity storage device assembly kit. The power storage device assembly kit includes, for example, the following 2 elements:
(2-a) an outer case accommodating the laminate or the wound body of the separator and the negative electrode obtained in the positive electrode and the 2 nd production method; the method comprises the steps of,
(2-b) a container for containing a nonaqueous electrolytic solution.
When the electricity storage device assembly kit is used, the laminate or the wound body of the element (2-a) is brought into contact with the nonaqueous electrolyte solution of the element (2-b) in the outer case, and the silane crosslinking reaction is performed in situ, whereby an electricity storage device that is compatible with both safety and output can be formed.
The power storage device assembly kit may include, as an accessory (or element (2-c)) in view of promoting the crosslinking reaction of the separator, another container that accommodates a catalyst for crosslinking the alkoxysilyl groups to siloxane bonds, for example, the above-described mixture containing the organometallic catalyst and water, an acid solution, an alkali solution, or the like.
The power storage device may be manufactured using the power storage device assembly kit described above. As a method for manufacturing an electric storage device using an electric storage device assembly kit, for example, the following steps may be included:
(2-a) preparing the power storage device assembly kit;
(2-B) a step of starting a silane crosslinking reaction of the silane-grafted modified polyolefin by bringing a separator (i.e., a heat-treated porous body obtained through the above steps (1) to (4)) in an electricity storage device assembly kit into contact with a nonaqueous electrolyte;
(2-C) a step of connecting lead terminals to the positive electrode and the negative electrode in the power storage device assembly kit, as desired;
(2-D) optionally performing charge/discharge for at least 1 cycle.
In the steps (2-a) to (2-D), the positive electrode, the negative electrode, the nonaqueous electrolytic solution, and the outer case may be any of those described above or those known in the art. From the viewpoint of reliably carrying out the silane crosslinking reaction of the separator, the (2-C) step and the (2-D) step are preferably carried out.
In the production method 2, the silane-grafted modified polyolefin is crosslinked upon contact with a nonaqueous electrolyte. Therefore, the silane crosslinking reaction is initiated after the production of the power storage device while being suitable for the conventional production process of the power storage device, and the safety of the power storage device can be improved.
Examples
Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples. The physical properties in the examples were measured as follows.
(1) Weight average molecular weight
Calibration curves were prepared using standard polystyrene measured under the following conditions using ALC/GPC 150C (trademark) manufactured by Waters corporation. In addition, the chromatogram was measured under the same conditions for each of the following polymers, and the weight average molecular weight of each polymer was calculated based on the calibration curve as follows.
Chromatographic column: cao Zhizao GMH from Kagakudong 6 HT (trademark) 2 root +GMH 6 HTL (trademark) 2
Mobile phase: o-dichlorobenzene
A detector: differential refractometer
Flow rate: 1.0ml/min
Column temperature: 140 DEG C
Sample concentration: 0.1wt%
(weight average molecular weight)
The weight average molecular weight was calculated by multiplying each molecular weight component in the obtained calibration curve by 0.43 (Q factor of polyethylene/Q factor of polystyrene=17.7/41.3) to obtain a molecular weight distribution curve in terms of polyethylene.
(weight average molecular weight of resin composition)
The weight average molecular weight was calculated in the same manner as in the case of polyethylene except that the Q factor value of the polyolefin having the largest mass fraction was used.
(2) Melt Flow Rate (MFR) (g/10 min)
The weight of the resin extruded at 230℃under a load of 2.16kg for 10 minutes was determined as an MFR value using a MELT flow rate measuring machine (MELT INDEXER F-F01) manufactured by Toyo Seisakusho Co.
(3) Film thickness (mum)
The film thickness of the microporous film was measured at room temperature of 23.+ -. 2 ℃ and relative humidity of 60% using a micro thickness gauge, KBM (trademark) manufactured by Toyo Seisakusho Co. Specifically, the film thickness at 5 points was measured at substantially equal intervals along the entire width in the TD direction, and the average value of these was obtained.
(4) Porosity (%)
A10 cm×10cm square sample was cut from the microporous membrane to determine the volume (cm) 3 ) And mass (g), based on these sum densities (g/cm 3 ) The porosity was calculated using the following formula. The density of the mixed composition is calculated and obtained from the respective densities and mixing ratios of the raw materials used.
Porosity (%) = (volume-mass/density of the mixed composition)/volume×100
(5) Air permeability and air permeability rise (sec/100 cm) 3 )
The air permeability of the microporous membrane was measured according to JIS P-8117 (2009) by using a GURLEY type air permeability meter, G-B2 (trademark) manufactured by Toyo Seisakusho Co.
(6) Quantification of resin agglomerates in separators
The resin aggregate in the separator is defined as an opaque region having an area of 100 μm or more in length by 100 μm or more in width when the separator obtained in examples and comparative examples described later is observed with a transmission type optical microscope. In observation based on a transmission-type optical microscope, measurement was made every 1000m 2 Number of resin agglomerates of the separator area.
(7) Rupture temperature (. Degree. C.) measured by TMA
The temperature at the moment when the load was completely released was determined as the TMA rupture temperature (rupture temperature measured by TMA) by changing the ambient temperature between 25 and 250 ℃ using a constant length mode of TMA50 (trademark) manufactured by shimadzu corporation.
Specifically, when measuring the MD direction, a microporous membrane having TD 3mm and MD 13mm was taken, both ends of the MD were clamped with a dedicated probe so that the clamp pitch was 10mm, a load of 1.0g was initially applied, the temperature of a furnace mounted on the test piece was raised, and the temperature at which the load was 0g was used as TMA membrane rupture temperature. In the measurement of the TD direction, a microporous film having a TD of 13mm and a MD of 3mm was obtained, and the same procedure as described above was carried out.
(8) Battery failure safety test (spike test)
The battery failure safety test is a test in which an iron nail is driven at a speed of 20mm/sec and penetrated to induce an internal short circuit in a battery charged to 4.5V. In this test, the phenomenon at the time of internal short circuit can be clarified by measuring the time-varying behavior of the voltage decrease of the battery caused by the internal short circuit and the behavior of the surface temperature increase of the battery caused by the internal short circuit. In addition, rapid heat generation of the battery may occur due to insufficient shutdown function of the separator at the time of internal short circuit and rupture of the membrane at low temperature, and accordingly, the nonaqueous electrolytic solution may catch fire, and the battery may smoke and/or explode.
(production of a Battery used in a Battery failure safety test)
a. Manufacturing of positive electrode
LiCoO as lithium cobalt composite oxide to be used as positive electrode active material 2 92.2 mass% of each of flake graphite and acetylene black as a conductive material, 2.3 mass% and polyvinylidene fluoride (PVDF) 3.2 mass% as a binder were dispersed in N-methylpyrrolidone (NMP) to prepare a slurry. The slurry was applied to one surface of an aluminum foil having a thickness of 20 μm constituting a positive electrode current collector by a die coater, dried at 130℃for 3 minutes, and then compression molded by a roll press. At this time, the coating amount of the active material of the positive electrode was adjusted to 250g/m 2 The volume density of the active substance is regulated to 3.00g/cm 3 。
b. Fabrication of negative electrode
96.9 mass% of artificial graphite as a negative electrode active material, 1.4 mass% of ammonium salt of carboxymethyl cellulose as a binder, and 1.7 mass% of styrene-butadiene copolymer latex were dispersed in purified water to prepare a slurry. The slurry was applied to one surface of a copper foil having a thickness of 12 μm constituting a negative electrode current collector by a die coater, dried at 120℃for 3 minutes, and then compression molded by a roll press. At this time, the coating amount of the active material of the negative electrode was adjusted to 106g/m 2 The volume density of the active substance is regulated to be 1.35g/cm 3 。
c. Preparation of nonaqueous electrolyte
In carbonic acidEthylene: methylethyl carbonate=1: 2 (volume ratio) of LiPF as a solute dissolved in a mixed solvent 6 So that the concentration reaches 1.0 mol/L.
d. Battery assembly
The separator was cut into TD 60mm and MD 1000mm, and the separator was repeatedly folded, and positive electrodes and negative electrodes (12 positive electrodes and 13 negative electrodes) were alternately laminated between the separators. The positive electrode used was a positive electrode having an area of 30mm×50mm, and the negative electrode used was a negative electrode having an area of 32mm×52 mm. The repeatedly folded laminate is put into a laminate bag, and then the nonaqueous electrolyte obtained in the above c is injected and sealed. After 1 day of standing at room temperature, the battery was charged to a battery voltage of 4.2V at a current value of 3mA (0.5C) in an atmosphere of 25℃and, after that, the current value was reduced from 3mA so as to be maintained at 4.2V, and the initial charge after the battery was produced for a total of 6 hours was performed by this method. Then, the battery was discharged to a battery voltage of 3.0V at a current value of 3mA (0.5C).
(maximum heating speed)
After the iron nails were inserted into the obtained battery, the maximum heat generation rate was determined from a temperature change chart obtained by measuring the surface temperature of the battery for 300 seconds using a thermocouple, and the rate at which the temperature increase change was maximum every 1 sec.
(time to decrease voltage)
After the iron nail was passed through the resulting battery, the time required for the voltage to decrease from 4.5V to 3V was determined as the voltage decrease time (time to decrease to 3V).
(9) Cycle characteristic evaluation and method for manufacturing battery thereof
The battery for cycle characteristic evaluation was fabricated according to the same method as the method a.about.c. for producing a battery used in the battery failure safety test of item "(8) above, but according to the following d..
The charge and discharge of the resulting battery were carried out for 100 cycles in an atmosphere at 60 ℃. Charging was performed by charging to a battery voltage of 4.2V at a current value of 6.0mA (1.0C), and after that, the current value was reduced from 6.0mA so as to maintain 4.2V, and charging was performed for a total of 3 hours. The discharge was discharged to a battery voltage of 3.0V at a current value of 6.0mA (1.0C). The capacity retention rate was calculated from the discharge capacity of the 100 th cycle and the discharge capacity of the 1 st cycle. The case where the capacity retention rate was high was evaluated as having good cycle characteristics.
d. Battery assembly
The separator was cut into a circular shape having a diameter of 18mm, the positive electrode and the negative electrode were cut into a circular shape having a diameter of 16mm, and the positive electrode, the separator, and the negative electrode were stacked in this order so that the positive electrode and the negative electrode face each other, and were housed in a stainless steel metal container with a lid. The container is insulated from the lid, the container is in contact with the copper foil of the negative electrode, and the lid is in contact with the aluminum foil of the positive electrode. The nonaqueous electrolyte obtained in c.of the above item "(8) battery failure safety test" was injected into the container, and the container was sealed. After 1 day of standing at room temperature, the battery was charged to a battery voltage of 4.2V at a current value of 3mA (0.5C) in an atmosphere of 25℃and, after that, the current value was reduced from 3mA by 4.2V, and the initial charge after the battery was fabricated for a total of 6 hours was performed by this method. Then, the battery was discharged to a battery voltage of 3.0V at a current value of 3mA (0.5C).
(10) Extrusion stability
The state of the extruded polyolefin composition was observed during the extrusion step, and evaluated according to the following criteria.
(good): the extruder current value was within + -0.5A at an average value of 300 seconds.
X (bad): the extruder current value varied by + -more than 0.5A at an average value of 300 seconds.
Example 1
< method for producing silane-grafted modified Polypropylene >
The raw material polyolefin used in the silane-grafted modified polypropylene has a viscosity average molecular weight (Mv) of 10 to 100 tens of thousands, a weight average molecular weight (Mw) of 3 to 92 tens of thousands, preferably 1 to 15 tens of thousands, and may be propylene or butene copolymerized alpha-olefin. While the raw polyolefin was melt-kneaded by an extruder, an organic peroxide (di-t-butyl peroxide) was added to generate radicals in the alpha-olefin polymer chain, and then trimethoxy alkoxy substituted vinyl silane was injected, and an alkoxysilyl group was introduced into the alpha-olefin polymer by an addition reaction to form a silane-grafted structure.
In addition, an antioxidant (pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ]) is added in an appropriate amount to control the radical concentration in the system, thereby suppressing chain reaction (gelation) in the alpha olefin. The obtained silane-grafted polyolefin molten resin was cooled in water, and after pellet processing, it was dried by heating at 80℃for 2 days to remove water or unreacted trimethoxy alkoxy substituted vinyl silane. The residual concentration of the unreacted trimethoxyalkoxy substituted vinyl silane pellets was about 1500ppm or less.
The silane-grafted modified polyolefin obtained by the above production method is hereinafter or in table 1 denoted as "silane-grafted modified polypropylene".
< preparation of microporous Membrane (Single layer) >)
Polyethylene (UHMWPE) of a homopolymer having a weight average molecular weight of 1,000,000 and the above silane-grafted modified polypropylene were blended as polyethylene: silane grafted modified polypropylene = 95:5 (mass%) of pentaerythritol-tetrakis- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate was added as an antioxidant]1 mass% and dry-blended using a drum mixer, thereby obtaining a mixture. The resulting mixture was fed from a feeder to a twin-screw extruder under a nitrogen atmosphere. Further, liquid paraffin (kinematic viscosity at 37.78 ℃ C. 7.59X10) -5 m 2 S) are injected into the extruder barrel.
The mixture and liquid paraffin were melt-kneaded in an extruder, and a feeder and a pump were adjusted so that the liquid paraffin accounted for 70% by mass (i.e., the polymer concentration was 30% by mass) in the extruded polyolefin composition. The melt kneading conditions were a set temperature of 230 ℃, a screw speed of 240rpm and a discharge amount of 18kg/h.
Next, the melt-kneaded product was extruded through a T die onto a cooling roll having a surface temperature controlled to 25℃and was cast, whereby a gel sheet (sheet) having a green film thickness of 1300. Mu.m was obtained.
(stretching step)
Then, the gel sheet was guided to a simultaneous biaxial stenter and biaxially stretched to obtain a stretched product. The stretching conditions were set to be 7.0 times MD magnification, 6.0 times TD magnification (i.e., 7X 6 times), and biaxial stretching temperature was set to 124 ℃.
(porous body Forming step)
Next, the stretched gel sheet was guided to a dichloromethane tank, immersed in dichloromethane sufficiently to extract and remove liquid paraffin, and then dried to remove dichloromethane, thereby obtaining a porous body.
(Heat treatment step)
Next, the porous body was guided to a TD stenter for heat setting, heat-set at a heat setting temperature of 131 ℃ and a stretching ratio of 1.8 times, and then subjected to a relaxation operation to TD of 1.7 times. Thus, a heat-treated porous body was obtained.
(affinity treatment step)
Next, the heat-treated porous body was introduced into an ethanol bath (affinity treatment tank), immersed and left for 60 seconds, and affinity treatment was performed on the heat-treated porous body to obtain an affinity-treated porous body.
(crosslinking treatment Process)
Then, the affinity-treated porous body was introduced into a 25% aqueous caustic soda solution (crosslinking treatment tank), immersed and left for 60 seconds, and the affinity-treated porous body was crosslinked to obtain a crosslinked porous body.
(washing and drying Process)
Next, the crosslinked porous body was introduced into water (water washing treatment tank), immersed and left for 60 seconds, and the crosslinked porous body was washed with water. This was guided to a conveyor dryer and dried at 120℃for 60 seconds to obtain a microporous membrane.
Then, the end portions of the obtained microporous film were cut, and the microporous film was wound into a master roll having a width of 1,100mm and a length of 5,000 m.
Examples 2 to 5 and comparative examples 1 to 3
A microporous membrane was produced in the same manner as in example 1, except that the conditions were changed as described in table 1.
The microporous films obtained in the examples and comparative examples were used for the evaluation. The evaluation results are shown in Table 1.
TABLE 1
/>
The silane-grafted modified polypropylene (a) in example 1 was: a polypropylene having a viscosity average molecular weight of 20,000 was used as a raw material, and a density of 0.91g/cm was obtained in a modification reaction based on trimethoxyalkoxy substituted vinylsilane 3 And a Melt Flow Rate (MFR) of 18.0g/min at 230 ℃.
In table 1, "resin composition" represents a mass ratio of 100 mass% with respect to the sum of the silane-grafted modified polypropylene (a) and the polyethylene (UHMWPE) (B).
Further, "mode" means a method of a silane crosslinking reaction, and is thus classified as a mode based on alkali treatment or acid treatment in the table.
The "time point of the crosslinking reaction" means whether the silane crosslinking reaction is performed in the crosslinking treatment step (6) or the step (2-IV) in the production method (2) (particularly, whether the silane crosslinking reaction is performed during the initial 1 st cycle charge/discharge of the power storage device).
The "reagent" means a reagent used in the crosslinking treatment step (6) described above, except for example 5 and comparative example 3. In example 4, a 10% hydrochloric acid solution was used as a reagent instead of the 25% caustic soda aqueous solution in example 1.
The "temperature" means the temperature in the step described in the time point of the crosslinking reaction.
The "pH of the crosslinking treatment tank" and "pH of the washing treatment tank" mean the pH in each tank, and for example, "7 to 12" means that the pH has a wide distribution from the vicinity of the inlet to the vicinity of the outlet of the tank.

Claims (10)

1. A separator for an electric storage device, wherein the mass ratio of silane-grafted modified polypropylene (A) to polyethylene (B), i.e., (A)/(B), is 2/98 to 5/95, and the rupture temperature as measured by thermo-mechanical analysis (TMA) is 170 to 210 ℃,
The density of the silane grafted modified polypropylene (A) is 0.82-0.96 g/cm 3 And a Melt Flow Rate (MFR) at 230 ℃ of 0.5 to 25g/min.
2. A method for manufacturing a separator for an electric storage device, comprising the steps of:
(1) A sheet molding step of extruding a silane-grafted modified polypropylene (A), an ultra-high molecular weight polyethylene (B), and a plasticizer, cooling and solidifying the extruded materials, and molding the extruded materials into a sheet having a mass ratio of (A)/(B) of 1/99 to 5/95;
(2) A stretching step of stretching the sheet to obtain a stretched product;
(3) A porous body forming step of extracting a plasticizer from the stretched material to form a porous body; the method comprises the steps of,
(4) A heat treatment step of heat-treating the porous body to obtain a heat-treated porous body,
the density of the silane grafted modified polypropylene (A) is 0.82-0.96 g/cm 3 And a Melt Flow Rate (MFR) at 230 ℃ of 0.5 to 25g/min.
3. The method for manufacturing a separator for an electric storage device according to claim 2, further comprising the steps of:
(5) An affinity treatment step of immersing the heat-treated porous body in an organic solvent having amphiphilicity to water and an organic substance to obtain an affinity-treated porous body;
(6) A crosslinking treatment step of bringing the affinity-treated porous body into contact with a mixture containing an organometallic catalyst and water, or immersing the affinity-treated porous body in an alkali solution or an acid solution to form a crosslinked porous body having a silane crosslinked structure; the method comprises the steps of,
(7) And a water washing and drying step of washing and drying the crosslinked porous body.
4. A method for manufacturing an electric storage device includes the following steps;
(2-I) a preparation step of preparing an outer case of a laminate or a wound body containing an electrode and the separator for an electric storage device according to claim 1, and a nonaqueous electrolytic solution; the method comprises the steps of,
(2-II) a liquid injection step of injecting the nonaqueous electrolytic solution into the outer case.
5. The method for producing an electrical storage device according to claim 4, wherein a silane crosslinking reaction of a silane-grafted modified polyolefin contained in the electrical storage device separator is started by bringing the electrical storage device separator into contact with the nonaqueous electrolytic solution during or after the liquid injection step.
6. The method for manufacturing an electrical storage device according to claim 4, wherein the nonaqueous electrolytic solution contains a fluorine-containing lithium salt.
7. The method for manufacturing an electrical storage device according to claim 4, wherein the nonaqueous electrolytic solution is an acid solution or an alkali solution.
8. The method for manufacturing an electrical storage device according to claim 4, further comprising the steps of:
(2-III) a terminal connection step of connecting a lead terminal to the electrode in the outer case or the electrode exposed from the outer case; the method comprises the steps of,
(2-IV) a charge/discharge step of performing charge/discharge for at least 1 cycle.
9. A lithium ion secondary battery comprising a positive electrode, a negative electrode, the separator for an electrical storage device according to claim 1, and a nonaqueous electrolytic solution.
10. An electric storage device comprising a positive electrode, a negative electrode, the separator for an electric storage device according to claim 1, and a nonaqueous electrolytic solution.
CN202010393355.7A 2019-08-26 2020-05-11 Crosslinked resin dispersion separator Active CN112510318B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019-153776 2019-08-26
JP2019153776 2019-08-26

Publications (2)

Publication Number Publication Date
CN112510318A CN112510318A (en) 2021-03-16
CN112510318B true CN112510318B (en) 2023-12-08

Family

ID=74716834

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010393355.7A Active CN112510318B (en) 2019-08-26 2020-05-11 Crosslinked resin dispersion separator

Country Status (3)

Country Link
JP (1) JP2021036515A (en)
KR (1) KR102371349B1 (en)
CN (1) CN112510318B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4239721A4 (en) * 2020-10-30 2024-06-05 Asahi Kasei Kabushiki Kaisha Siloxane dispersed crosslinked separator

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09216964A (en) * 1996-02-09 1997-08-19 Nitto Denko Corp Porous film, and separator for cell and cell using the same
JP2001176484A (en) * 1999-12-15 2001-06-29 Nitto Denko Corp Porous film
JP2011111484A (en) * 2009-11-25 2011-06-09 Asahi Kasei E-Materials Corp Polyolefin-made microporous film
CN102791485A (en) * 2010-03-18 2012-11-21 三菱树脂株式会社 Porous polyolefin resin film and separator for battery
WO2013047600A1 (en) * 2011-09-26 2013-04-04 旭化成イーマテリアルズ株式会社 Microporous membrane
JP2013119583A (en) * 2011-12-07 2013-06-17 Mitsubishi Chemicals Corp Silane-grafted polyolefin, and silane-crosslinked polyolefin resin
KR20130075790A (en) * 2008-12-19 2013-07-05 아사히 가세이 이-매터리얼즈 가부시키가이샤 Polyolefin micro-porous membrane and lithium ion secondary battery separator
KR20160129580A (en) * 2015-04-30 2016-11-09 주식회사 엘지화학 Manufacturing method of separator and separator manufactured by the same method
CN106920912A (en) * 2017-04-14 2017-07-04 上海恩捷新材料科技股份有限公司 A kind of preparation method of lithium ion battery barrier film
JP2017203145A (en) * 2016-05-13 2017-11-16 積水化学工業株式会社 Heat-resistant synthetic resin microporous film and separator for battery
KR101955911B1 (en) * 2018-08-23 2019-03-12 더블유스코프코리아 주식회사 A separator and a method for manufacturing the same

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997044839A1 (en) 1996-05-22 1997-11-27 Kureha Chemical Industry Co., Ltd. Porous film and separator for batteries comprising porous film
JPH11144700A (en) 1997-11-06 1999-05-28 Kureha Chem Ind Co Ltd Porous membrane, battery separator comprising porous membrane, and manufacture thereof
JPH11172036A (en) 1997-12-10 1999-06-29 Kureha Chem Ind Co Ltd Porous film, battery separator comprising porous film, and its production
JP2000319441A (en) 1999-05-12 2000-11-21 Toray Ind Inc Production of microporous resin film
DE102011109506B4 (en) * 2011-08-05 2019-12-05 Audi Ag Refrigerant circulation

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09216964A (en) * 1996-02-09 1997-08-19 Nitto Denko Corp Porous film, and separator for cell and cell using the same
JP2001176484A (en) * 1999-12-15 2001-06-29 Nitto Denko Corp Porous film
KR20130075790A (en) * 2008-12-19 2013-07-05 아사히 가세이 이-매터리얼즈 가부시키가이샤 Polyolefin micro-porous membrane and lithium ion secondary battery separator
JP2011111484A (en) * 2009-11-25 2011-06-09 Asahi Kasei E-Materials Corp Polyolefin-made microporous film
CN102791485A (en) * 2010-03-18 2012-11-21 三菱树脂株式会社 Porous polyolefin resin film and separator for battery
WO2013047600A1 (en) * 2011-09-26 2013-04-04 旭化成イーマテリアルズ株式会社 Microporous membrane
JP2013119583A (en) * 2011-12-07 2013-06-17 Mitsubishi Chemicals Corp Silane-grafted polyolefin, and silane-crosslinked polyolefin resin
KR20160129580A (en) * 2015-04-30 2016-11-09 주식회사 엘지화학 Manufacturing method of separator and separator manufactured by the same method
JP2017203145A (en) * 2016-05-13 2017-11-16 積水化学工業株式会社 Heat-resistant synthetic resin microporous film and separator for battery
CN106920912A (en) * 2017-04-14 2017-07-04 上海恩捷新材料科技股份有限公司 A kind of preparation method of lithium ion battery barrier film
KR101955911B1 (en) * 2018-08-23 2019-03-12 더블유스코프코리아 주식회사 A separator and a method for manufacturing the same

Also Published As

Publication number Publication date
KR20210024953A (en) 2021-03-08
CN112510318A (en) 2021-03-16
JP2021036515A (en) 2021-03-04
KR102371349B1 (en) 2022-03-07

Similar Documents

Publication Publication Date Title
CN111602265B (en) Separator for lithium ion battery
US8003261B2 (en) Polyolefin microporous membrane
CN111630687B (en) Lithium ion battery using cross-linked separator
JP7461381B2 (en) Inorganic coating layer crosslinked separator
CN112510318B (en) Crosslinked resin dispersion separator
JP7160621B2 (en) Trace metal cross-linked separator
KR100970021B1 (en) Porous film, battery separator comprising the film, and non-aqueous electrolyte battery using the separator
JP6277225B2 (en) Storage device separator
CN112500624B (en) Separator using silane crosslinked polyolefin hybrid resin
JP2023528717A (en) Compositions, articles, devices containing silicone, and methods for making them
CN114424398A (en) Crosslinked separator for lithium secondary battery comprising crosslinked polyolefin and method for producing same
JP7498571B2 (en) Microporous membrane for power storage devices
JP7462461B2 (en) Polyolefin laminated microporous membrane
CN115172985B (en) Method for manufacturing separator for power storage device
EP4329074A1 (en) Method for manufacturing separator containing cross-linked structure for lithium secondary battery, separator containing cross-linked structure for lithium secondary battery manufactured using same, and lithium secondary battery comprising same
EP4372893A1 (en) Method for manufacturing lithium secondary battery separator having cross-linked structure, lithium secondary battery separator having cross-linked structure, manufactured thereby, and lithium secondary battery comprising same
JP2022047639A (en) Polyolefin microporous film, separator for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery
TW200830616A (en) Electrode assembly and non-aqueous electrolyte battery

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant