JP2007134149A - Nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent internal short circuit without installing an insulating coating member in the interior of a nonaqueous electrolyte battery. <P>SOLUTION: In the respective parts with a possibility of internal short circuit such as a part in which the positive electrode end part is opposed to a negative electrode via a separator and a part in which the negative electrode end part is opposed to a positive electrode via the separator, a shut down part is installed on one part of the separator in which the positive electrode end part and the negative electrode end part are neighbored. Then, the shut down part is the part in which density is increased by crushing voids of the separator by heating and pressurizing the separator and a piercing strength is improved, and constituted so that the piercing strength becomes 250 gf and voided fraction becomes 20% or less. This shut down part is installed so as to cover the positive electrode end part and the positive electrode active material coating end part, as well as the negative electrode end part and the negative electrode active material coating end part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nonaqueous electrolyte battery, and more particularly to a nonaqueous electrolyte battery having a configuration capable of preventing a short circuit between a positive electrode and a negative electrode during pressing without using an insulating coating material.

  In recent years, many portable electronic devices such as a camera-integrated VTR (Videotape recorder), a mobile phone, or a laptop computer have appeared, and their size and weight have been reduced. Along with this, the demand for batteries used as power sources for portable electronic devices is growing rapidly, and the battery design is lighter, thinner, and more efficient in the storage space in devices to realize smaller and lighter devices. It is required to use. As a battery satisfying such requirements, a lithium ion battery having a large energy density and output density is most suitable.

  Among them, a battery having a high degree of freedom of shape, a thin and large area sheet type battery, a thin and small area card type battery, and the like are desired. However, in the conventional method using a metal can as an exterior, it is thin. It is difficult to produce a battery. Therefore, it is possible to obtain a battery as described above by producing a thin battery using a film-like exterior material such as an aluminum laminate film.

  Such a battery is produced by laminating a positive electrode and a negative electrode through a separator, covering a wound or zigzag battery element with a laminate film, and sealing the periphery of the battery element. A positive electrode terminal and a negative electrode terminal connected to the negative electrode (hereinafter, appropriately referred to as an electrode terminal unless otherwise specified) are led out of the battery from the sealing portion of the laminate film.

  One method for effectively increasing the battery capacity of such a non-aqueous electrolyte battery is to make the separator thinner and increase the amount of the space active material. However, the thin separator is weak and easily damaged by the pressure that the battery receives from the outside. For this reason, there exists a possibility that a positive electrode and a negative electrode may contact and short-circuit.

  On the other hand, in the case of a non-aqueous electrolyte battery using a gel-like or plastic electrolyte, the electrolyte may not adhere to the electrode, so that electrical contact is insufficient compared to the case where a liquid electrolyte (electrolyte) is used. There is a case. In such a case, the electrode portion that is not in contact with the electrolyte does not contribute to the reaction, and if the electrolyte is not sufficiently in contact, the ion mobility is not sufficient, resulting in a lower battery capacity than originally obtained. . In addition, when the contact of the electrolyte is insufficient, the contact resistance between the electrode and the electrolyte increases, and the internal resistance of the battery increases.

  Therefore, in a non-aqueous electrolyte battery using a gel-like or plastic electrolyte, pressure is applied to the battery element after fabrication so that the electrode and the electrolyte are sufficiently adhered.

  However, by providing such a process, the positive electrode and the negative electrode come into contact with each other and short-circuiting easily occurs. This is because when the pressure is applied from the outside of the battery element, the shape of the electrolyte is deformed, the electrodes are easily brought into contact, the electrode current collector ends and the electrode terminals are warped, and the burrs generated during cutting are pressured. This is to break through the separator.

  In order to solve such a problem, in Patent Document 1 below, insulating coating materials 6a to 6f such as a protective tape whose base material is made of an insulating material as shown in FIG. 1 are provided on the electrode. A battery configuration that prevents the separators 3a and 3b from being damaged and prevents short-circuiting inside the battery is described.

JP 2001-266946 A

  In this battery, a positive electrode 1 having a positive electrode active material layer 1a provided on a positive electrode current collector 1b, a negative electrode 2 having a negative electrode current collector 1b provided on a negative electrode current collector 1b, separators 3a and 3b, A positive electrode terminal 5 a and a negative electrode terminal 5 b are connected to the positive electrode 1 and the negative electrode 2, respectively. The insulating covering materials 6a to 6f are provided in the portion where the electrodes may come into contact with each other at the electrode end portion, the electrode terminal portion, and the portion facing the electrode end portion.

  However, in the case of the battery configuration as in Patent Document 1, by providing several insulating coating materials having a thickness of about several tens of μm, the battery capacity for the insulating coating material is reduced. . In addition, by providing an insulating coating material, a step of about 30 μm is generated at the end of the insulating coating material, a step is generated in the electrode itself, or a stress generated by winding an electrode around the end of the insulating coating material May occur, and the electrode may be bent to reduce the roundness, leading to deterioration of battery characteristics.

  Accordingly, an object of the present invention is to provide a non-aqueous electrolyte battery capable of reducing the thickness of the battery without providing an insulating coating material inside the battery element and preventing a short circuit due to damage to the separator and contact between electrodes. And

  In order to solve the above-described problem, in the present invention, a separator portion adjacent to a portion that may damage the separator, such as a portion where one end portion of the electrode faces the other electrode through the separator, is heated and pressurized. Thus, the puncture strength is improved and a nonaqueous electrolyte battery is produced.

  Note that the shutdown portion provided by heating and pressurizing has a puncture strength of 250 gf or more and a porosity of 20% or less.

  By using such a method, it is possible to improve the separator strength in the portion adjacent to the electrode end portion without providing an insulating coating material.

  According to the present invention, the internal volume of the battery is not wasted, and the battery capacity can be improved. In addition, even when a thin separator is used, the puncture strength can be improved by performing the heating / pressurizing treatment, so that both safety and further improvement in battery capacity can be achieved.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 2 is a schematic diagram showing an example of the configuration of a nonaqueous electrolyte battery to which the present invention is applied. The non-aqueous electrolyte battery 10 is produced by sealing a peripheral portion of the battery element 20 in which the battery element 20 is accommodated in a battery element accommodating portion 18 a that is a recess formed in the laminate film 18. ing. Hereinafter, the configuration of the battery element 20 will be described.

  FIG. 3 shows the appearance of the battery element 20. The battery element 20 is formed by sequentially laminating a strip-like positive electrode 11, a separator 13a, a strip-like negative electrode 12 disposed to face the positive electrode 11, and a separator 13b, and is wound in the longitudinal direction. A gel electrolyte (not shown) is applied to both surfaces of the negative electrode 12. A positive electrode terminal 15a connected to the positive electrode 11 and a negative electrode terminal 15b connected to the negative electrode 12 are led out from the battery element 20, and the positive electrode terminal 15a and the negative electrode terminal 15b have adhesiveness to a laminate film 18 to be packaged later. In order to improve, sealants 16a and 16b made of polyethylene (PE) or the like are disposed.

[Positive electrode]
In the positive electrode 11, a positive electrode active material layer 11 a containing a positive electrode active material is formed on both surfaces of a positive electrode current collector 11 b. As the positive electrode current collector 11b, for example, a metal foil such as an aluminum (Al) foil, a nickel (Ni) foil, or a stainless steel (SUS) foil can be used.

  The positive electrode active material layer 11a includes, for example, a positive electrode active material, a conductive agent, and a binder. Here, the positive electrode active material, the conductive agent, and the binder need only be uniformly dispersed, and the mixing ratio is not limited.

As the positive electrode active material, a metal oxide, a metal sulfide, or a specific polymer can be used depending on the type of the target battery. For example, in the case of constituting a lithium ion battery, Li _x MO ₂ (wherein M represents one or more transition metals, and x varies depending on the charge / discharge state of the battery, and is usually 0.05 or more and 1.10 or less. ) And a composite oxide of lithium and transition metal. As the transition metal constituting the lithium composite oxide, cobalt (Co), Ni, manganese (Mn) or the like is used.

Specific examples of such a lithium composite oxide include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _y Co _1-y O ₂ (0 <y <1). A solid solution in which a part of the transition metal element is substituted with another element can also be used. Examples thereof include LiNi _0.5 Co _0.5 O ₂ and LiNi _0.8 Co _0.2 O ₂ . These lithium composite oxides can generate a high voltage and have an excellent energy density. _{Furthermore, TiS 2, MoS 2, NbSe} 2, V 2 O no lithium metal sulfides such as ₅ or may be used an oxide as the positive electrode active material. These positive electrode active materials may be used alone or in combination of two or more.

  As the conductive agent, for example, a carbon material such as carbon black or graphite is used. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene or the like is used.

  The above-described positive electrode active material, binder, and conductive agent are uniformly mixed to form a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent to form a slurry. Next, the slurry is uniformly applied on the positive electrode current collector by a doctor blade method or the like, and then dried at a high temperature to drive off the solvent, thereby forming the positive electrode active material layer 11a. In addition, as a solvent, N-methylpyrrolidone etc. are used, for example.

  The positive electrode 11 has a positive electrode terminal 15a connected to one end of the positive electrode current collector 11b by spot welding or ultrasonic welding. The positive electrode terminal 15a is preferably a metal foil or a mesh-like one, but there is no problem even if it is not metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material of the positive electrode terminal 15a include aluminum.

[Negative electrode]
The negative electrode 12 is obtained by forming a negative electrode active material layer 11a containing a negative electrode active material on both surfaces of a negative electrode current collector 12b. The negative electrode current collector 12b is made of a metal foil such as a copper (Cu) foil, a nickel foil, or a stainless steel foil.

  The negative electrode active material layer 11a includes, for example, a negative electrode active material, a conductive agent if necessary, and a binder. These are uniformly mixed to form a negative electrode mixture, and this negative electrode mixture is dispersed in a solvent to form a slurry. Next, the slurry is uniformly applied on the negative electrode current collector by a doctor blade method or the like, dried at a high temperature, and the solvent is blown off to form a negative electrode active material layer. Here, the mixing ratio of the negative electrode active material, the conductive agent, the binder, and the solvent is not limited as in the positive electrode active material.

As the negative electrode active material, lithium metal, a lithium alloy, a carbon material that can be doped / undoped with lithium, or a composite material of a metal material and a carbon material is used. Specific examples of the carbon material that can be doped / undoped with lithium include graphite, non-graphitizable carbon, and graphitizable carbon. More specifically, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke), graphites, glassy carbons, organic polymer compound fired bodies (phenolic resin, furan resin, etc.) at an appropriate temperature. Carbon materials such as those obtained by firing and carbonization), carbon fibers, activated carbon, and the like can be used. Furthermore, as a material that can be doped / undoped with lithium, polymers such as polyacetylene and polypyrrole, and oxides such as SnO ₂ can be used.

  In addition, various types of metals can be used as materials capable of alloying lithium, but metallic lithium alone or alloys thereof are often used. When metallic lithium is used, it is not always necessary to use powder as a coating film with a binder, and a method of pressure bonding a rolled lithium metal foil to a current collector may be used.

  As the binder, for example, polyvinylidene fluoride, styrene butadiene rubber or the like is used. Moreover, as a solvent, N-methylpyrrolidone, methyl ethyl ketone, etc. are used, for example.

  The above-described negative electrode active material, binder, and conductive agent are uniformly mixed to form a negative electrode mixture, which is dispersed in a solvent to form a slurry. Subsequently, after apply | coating uniformly on a negative electrode electrical power collector by the method similar to a positive electrode, the negative electrode active material layer 12a is formed by drying at high temperature and flying a solvent.

  Similarly to the positive electrode 11, the negative electrode 12 has a negative electrode terminal 15b connected to one end of the negative electrode current collector by spot welding or ultrasonic welding, and the negative electrode terminal 15b is electrochemically and chemically stable. There is no problem even if it is not metal as long as it can conduct electricity. Examples of the material of the negative electrode terminal 15b include copper and nickel.

  The positive electrode terminal 15a and the negative electrode terminal 15b are preferably derived from the same direction, but there is no problem regardless of the direction from which the positive terminal 15a and the negative electrode terminal 15b are derived as long as no short circuit occurs. Moreover, the connection location of the positive electrode terminal 15a and the negative electrode terminal 15b is not limited to the above example as long as electrical contact is established, and the attachment location and the attachment method are not limited to the above example.

[Electrolytes]
As the electrolyte, an electrolyte salt and an organic solvent that are generally used in lithium ion batteries can be used. In addition to an electrolyte having a gel form and plasticity, an electrolyte can also be used.

  Specific examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, ethyl propyl carbonate, or hydrogen of these carbonic acid esters to halogen. Examples include substituted solvents. One of these solvents may be used alone, or a plurality of these solvents may be mixed with a predetermined composition.

Moreover, as lithium salt, it is possible to use the material used for normal battery electrolyte solution. Specifically, LiCl, LiBr, LiI, LiClO ₃ , LiClO ₄ , LiBF ₄ , LiPF ₆ , LiNO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiAlCl ₄ , LiSiF _{6 and the} like can be mentioned, but LiPF ₆ and LiBF ₄ are preferable from the viewpoint of oxidation stability. These lithium salts may be used alone or in combination of two or more. There is no problem as long as the lithium salt can be dissolved in the above solvent, but the lithium ion concentration is 0.4 mol / kg or more and 2.0 mol / kg or less with respect to the non-aqueous solvent. Preferably there is.

  In the case of using a gel electrolyte, the above-described electrolytic solution is gelled with a matrix polymer. The matrix polymer only needs to be compatible with a nonaqueous electrolytic solution in which the electrolyte salt is dissolved in the nonaqueous solvent and can be gelled. Examples of such a matrix polymer include a polymer containing polyvinylidene fluoride, polyethylene oxide, polypropylene oxide, polyacrylonitrile, and polymethacrylonitrile in repeating units. Such a polymer may be used individually by 1 type, and may mix and use 2 or more types.

Among them, particularly preferred as the matrix polymer is polyvinylidene fluoride or a copolymer in which hexafluoropropylene is introduced at a ratio of 7.5% or less to polyvinylidene fluoride. Such polymers have a number average molecular weight in the range of 5.0 × 10 ⁵ to 7.0 × 10 ⁵ (500,000 to 700,000) or a weight average molecular weight of 2.1 × 10 ⁵ to 3. The range is 1 × 10 ⁵ (210,000-310,000), and the intrinsic viscosity is in the range of 1.7 to 2.1.

[Separator]
The separator 13 is composed of, for example, a porous film made of a polyolefin-based material such as polyethylene (PE) or polypropylene (PP), or a porous film made of an inorganic material such as a ceramic nonwoven fabric. The porous film may be laminated. Among these, polyethylene and polypropylene porous films are the most effective.

  At this time, the thickness of the separator is preferably 1 to 9 μm. If the thickness of the separator is less than 1 μm, the mechanical strength of the film will decrease, and as will be described later, sufficient puncture strength cannot be obtained even if the separator is heated and pressurized, causing a short circuit inside the battery. End up. Further, when the thickness exceeds 10 μm, the capacity deterioration after 100 cycles becomes significant. In addition, the active material filling amount is reduced to lower the battery capacity, and the ionic conductivity is reduced to deteriorate the current characteristics.

[Production of battery]
The gel electrolyte solution prepared as described above is uniformly applied to the positive electrode 11 and the negative electrode 12 and impregnated in the positive electrode active material layer and the negative electrode active material layer, and then stored at room temperature or subjected to a drying process. A state electrolyte layer is formed. Next, using the positive electrode 11 and the negative electrode 12 on which the gel electrolyte layer is formed, the positive electrode 11, the separator 13 a, the negative electrode 12, and the separator 13 b are stacked and wound in this order to form the battery element 20.

  At this time, in the battery element 20 after being wound, the end portion of either the positive electrode or the negative electrode is opposed to the other electrode through the separator, and is adjacent to the electrode end portion in a portion where there is a possibility of contact. A part of the separator to be heated is subjected to heat and pressure treatment to crush the pores of the separator to increase the density, thereby improving the piercing strength. In this specification, performing such a heating / pressurizing process on the separator to improve the separator strength is referred to as shutdown.

  FIG. 4 shows a state when the battery element is wound. Reference numeral 21 is an element winding part, and reference numeral 22 is a separator heat treatment part. In the element winding unit 21, the positive electrode 11, the separator 13 a, the negative electrode 12, and the separator 13 b are stacked and wound using the winding core 23. Moreover, in the separator heat processing part 22, the separator of a desired part is shut down by heating while applying pressure from above and below the separator.

  The shutdown portion has a piercing strength of 250 gf or more and a porosity of the shutdown portion of 20% or less. Regardless of the thickness of the separator, safety is ensured by configuring the shutdown portion so that the piercing strength is 250 gf or more and the porosity is 20% or less. In addition, the shutdown position of the separator can be provided other than the separator portion adjacent to the electrode end portion, if necessary.

  FIG. 5 shows a cross section of the battery element 20 thus manufactured. A portion indicated by reference numerals 17a to 17d is a shutdown portion. In addition, when not specifically limited, it calls the shutdown part 17 suitably. Moreover, although the gel electrolyte is apply | coated to both surfaces of the positive electrode 11 and the negative electrode 12, it is not illustrated in FIG.

  As shown in FIG. 5, in the battery element 20 after winding, the shutdown portions 17a and 17b and the shutdown portions 17c and 17d of the separators 13a and 13b are connected to the end of the positive electrode 11 and the negative electrode 12 which may damage the separator. It arrange | positions so that each edge part may be covered.

  The shutdown portion 17 has sufficiently stronger strength than other separator portions that are not subjected to shutdown processing, and can prevent a short circuit inside the battery without using a conventionally used insulating coating material.

  Further, it is desirable that the shutdown portion 17 is configured to cover the end portions of the positive electrode active material layer 11a and the negative electrode active material layer 12a. The active material application end portion is more likely to rise or have protrusions than the central portion when the active material layer is formed, but the active material slurry before drying has a high viscosity and is often not smoothed by the leveling of the active material itself. For this reason, the active material application end part after drying may become an edge shape which may damage the separator, and it is as dangerous as the burr at the electrode end part. For this reason, the safety | security can be improved more by arrange | positioning the shutdown part 17 also in the part facing an active material application | coating edge part.

  The battery element 20 thus produced is covered with a laminate film 18 as shown in FIG. 2, and the periphery of the battery element 20 is sealed to produce the nonaqueous electrolyte battery 10. Since this non-aqueous electrolyte battery 10 does not use an insulating coating material inside the battery, the volume efficiency can be improved and the same safety as that of a conventional battery can be maintained.

  Hereinafter, the present invention will be specifically described with reference to examples.

(1) Puncture strength and porosity of the shutdown portion First, the puncture strength and porosity of the shutdown portion that can ensure safety are measured.

(I) Measurement of puncture strength In the battery element after winding, like the battery element shown in FIG. 5, the shutdown part is arranged at the part where one electrode end part faces the other electrode through the separator. Thus, a battery element is produced. At this time, the battery element is manufactured by setting the puncture strength of the shutdown portion to 150 gf, 200 gf, 250 gf, 300 gf, 350 gf, and 400 gf. A pressure was applied from the outside of the battery element in order to bring the gel electrolyte and the electrode into sufficient contact with each other, and then a non-aqueous electrolyte battery was produced by covering with a laminate film.

  1000 such nonaqueous electrolyte batteries were pierced for each strength, and the occurrence rate of internal short circuit was measured. Each of the batteries as described above was charged, and the battery that could not be charged was a battery in which an internal short circuit occurred.

  FIG. 6 shows the measurement results of (i). As can be seen from FIG. 6, when the puncture strength of the shutdown portion is 200 gf or less, the internal short-circuit occurrence rate exceeds 90%, whereas when the puncture strength of the shutdown portion is 250 gf or more, the internal short-circuit occurrence rate is approximately 0%. It was found that sufficient safety can be secured.

(Ii) Porosity measurement A non-aqueous electrolyte battery was prepared in the same manner as in (i) Puncture strength measurement except that the porosity of the shutdown portion was 5%, 10%, 20%, and 25%. The incidence of internal short circuit was measured.

  FIG. 7 shows the measurement results of (ii). As can be seen from FIG. 7, when the porosity of the shutdown portion is 25%, the internal short-circuit occurrence rate exceeds 90%, whereas when the porosity of the shutdown portion is 20% or less, the internal short-circuit occurrence rate is approximately It became 0%, and it turned out that sufficient safety can be secured.

(2) Measurement of battery performance Next, the separator thickness and the arrangement position of the shutdown portion are respectively changed to produce a nonaqueous electrolyte battery, and the battery performance is confirmed. First, a battery element is produced.

[Production of positive electrode]
A positive electrode mixture was prepared by uniformly mixing 92% by weight of lithium cobaltate (LiCoO ₂ ), 3% by weight of powdered polyvinylidene fluoride and 5% by weight of powdered graphite, and this was dispersed in N-methylpyrrolidone. To make a slurry. This slurry was uniformly applied to both surfaces of an Al foil serving as a positive electrode current collector, and dried under reduced pressure at 100 ° C. for 24 hours to form a positive electrode active material layer.

  Next, this was pressure-formed by a roll press machine to obtain a positive electrode sheet. The positive electrode sheet was cut into a strip shape to form a positive electrode, and an Al ribbon lead having a width of 3 mm was welded to an uncoated portion of the active material.

[Production of negative electrode]
A negative electrode mixture was prepared by uniformly mixing 91% by weight of artificial graphite and 9% by weight of powdered polyvinylidene fluoride, and dispersed in N-methylpyrrolidone to obtain a slurry. Next, this slurry was uniformly applied on both surfaces of a copper foil serving as a negative electrode current collector, and dried under reduced pressure at 120 ° C. for 24 hours to form a negative electrode active material layer.

  Next, this was pressure-formed by a roll press machine to obtain a negative electrode sheet, the negative electrode sheet was cut into a strip shape to form a negative electrode, and a Ni ribbon lead having a width of 3 mm was welded to an uncoated portion of the substance.

[Preparation of gel electrolyte]
A polyvinylidene fluoride copolymerized with 6.9% of hexafluoropropylene, a non-aqueous electrolyte, and dimethyl carbonate (DMC) as a diluting solvent are mixed, stirred and dissolved to obtain a sol electrolyte solution. Obtained. The electrolyte was prepared by mixing ethylene carbonate and propylene carbonate in a weight ratio of 6: 4 and dissolving 0.8 mol / kg LiPF ₆ and 0.2 mol / kg LiBF ₄ . The mixing ratio was a weight ratio of polyvinylidene fluoride: electrolyte: DMC = 1: 6: 12. Next, the obtained sol-form electrolyte solution was uniformly applied to both surfaces of the positive electrode and the negative electrode. Subsequently, after drying at 50 degreeC for 3 minute (s), the solvent was removed and the gel electrolyte layer was formed on both surfaces of the positive electrode and the negative electrode.

  Subsequently, a battery is obtained by laminating a belt-like positive electrode having a gel electrolyte layer formed on both sides and a belt-like negative electrode having a gel electrolyte layer formed on both surfaces via a separator and winding in a longitudinal direction. A device was prepared and packaged with a laminate film to obtain a nonaqueous electrolyte battery. At this time, either a separator having a shutdown portion with a puncture strength of 250 gf or more and a porosity of 20% or less or a separator without a shutdown portion was used, and a protective tape was used in combination when a separator without a shutdown portion was used. Moreover, the battery element was produced by changing the position of the shutdown portion or the protective tape and the thickness of the separator.

  At this time, the arrangement position of the shutdown part or the protective tape is set as A to D and A ′ to D ′ below.

  First, when a separator provided with a shutdown portion is used, A when the shutdown portions 17a, 17b, 17c, and 17d shown in FIG. 5 are all provided, B when no shutdown portion is provided, and the shutdown portions 17a and 17b. Only C is provided, and D is provided only shutdown portions 17c and 17d.

  Further, when a separator without a shutdown portion and a protective tape are used in combination, A ′ is used when all of the protective tapes 6a, 6b, 6c, 6d, 6e, and 6f shown in FIG. 1 are provided, and no protective tape is provided. B ′, when the protective tapes 6a and 6d are provided only at the electrode ends facing the other electrodes via the separator, the electrode ends facing the protective tape at C ′ and C ′ are opposed via the separator. The case where the protective tapes 6b, 6c, 6e, and 6f are provided only in the portion is D ′.

<Example 1>
A battery element was fabricated using a 1 μm thick separator having a shutdown portion, with the location of the shutdown portion being A.

<Example 2>
A battery element was produced in the same manner as in Example 1 except that the separator thickness was 5 μm.

<Example 3>
A battery element was produced in the same manner as in Example 1 except that the separator thickness was 9 μm.

<Comparative Example 1>
A battery element was produced in the same manner as in Example 1 except that the separator thickness was 0.7 μm.

<Comparative example 2>
A battery element was produced in the same manner as in Example 1 except that the separator thickness was 12 μm.

<Comparative Example 3>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was B and the separator thickness was 0.7 μm.

<Comparative example 4>
A battery element was produced in the same manner as in Example 1 except that the position of the shutdown portion was set to B.

<Comparative Example 5>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was B and the separator thickness was 5 μm.

<Comparative Example 6>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was B and the separator thickness was 9 μm.

<Comparative Example 7>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was B and the separator thickness was 12 μm.

<Comparative Example 8>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was C and the separator thickness was 0.7 μm.

<Comparative Example 9>
A battery element was produced in the same manner as in Example 1 except that the arrangement position of the shutdown portion was C.

<Comparative Example 10>
A battery element was produced in the same manner as in Example 1 except that the position of the shutdown portion was C and the separator thickness was 5 μm.

<Comparative Example 11>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was C and the separator thickness was 9 μm.

<Comparative Example 12>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was C and the separator thickness was 12 μm.

<Comparative Example 13>
A battery element was produced in the same manner as in Example 1 except that the position of the shutdown portion was D and the separator thickness was 0.7 μm.

<Comparative example 14>
A battery element was produced in the same manner as in Example 1 except that the position of the shutdown portion was D.

<Comparative Example 15>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was D and the separator thickness was 5 μm.

<Comparative Example 16>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was D and the separator thickness was 9 μm.

<Comparative Example 17>
A battery element was fabricated in the same manner as in Example 1 except that the position of the shutdown portion was D and the separator thickness was 12 μm.

<Comparative Example 18>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at A ′, and the separator thickness was 0.7 μm.

<Comparative Example 19>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used and the position of the protective tape was changed to A ′.

<Comparative Example 20>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at A ′, and the separator thickness was 5 μm.

<Comparative Example 21>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at A ′, and the separator thickness was 9 μm.

<Comparative Example 22>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at A ′, and the separator thickness was 12 μm.

<Comparative Example 23>
A battery element was fabricated in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at B ′, and the separator thickness was 0.7 μm.

<Comparative Example 24>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used and the position of the protective tape was changed to B ′.

<Comparative Example 25>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used and the protective tape was disposed at a B ′ separator thickness of 5 μm.

<Comparative Example 26>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used and the protective tape was disposed at a B ′ separator thickness of 9 μm.

<Comparative Example 27>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used and the protective tape was disposed at a B ′ separator thickness of 12 μm.

<Comparative example 28>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at C ′, and the separator thickness was 0.7 μm.

<Comparative Example 29>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used and the position of the protective tape was changed to C ′.

<Comparative Example 30>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at C ′, and the separator thickness was 5 μm.

<Comparative Example 31>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at C ′, and the separator thickness was 9 μm.

<Comparative Example 32>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at C ′, and the separator thickness was 12 μm.

<Comparative Example 33>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at D ′, and the separator thickness was 0.7 μm.

<Comparative Example 34>
A battery element was produced in the same manner as in Example 1 except that the separator without the shutdown portion was used and the protective tape was placed at D ′.

<Comparative Example 35>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at D ′, and the separator thickness was 5 μm.

<Comparative Example 36>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at D ′, and the separator thickness was 9 μm.

<Comparative Example 37>
A battery element was produced in the same manner as in Example 1 except that a separator without a shutdown portion was used, the protective tape was placed at D ′, and the separator thickness was 12 μm.

  Next, in order to sufficiently adhere the gel electrolyte to the electrode, pressure was applied from the outside of the battery element, and then it was covered with a laminate film to obtain a nonaqueous electrolyte battery.

(Iii) Measurement of internal short circuit occurrence rate 1000 batteries were prepared for each of the examples and comparative examples, and the internal short circuit occurrence rate was measured. The batteries were charged for each of the examples and comparative examples, and the batteries that could not be charged were those in which an internal short circuit occurred.

  Table 1 below shows the measurement results.

  As can be seen from Comparative Example 1, when the separator thickness is 0.7 μm, the internal short-circuit occurrence rate is high even if the shutdown part is arranged in all parts. In addition, when the separator thickness is 1 μm or more, it can be understood that the internal short circuit of the battery can be prevented as in the case of using the insulating tape if the shutdown portion is arranged in all the portions.

(IV) Measurement of Battery Thickness Each of Example 1 to Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 18 to Comparative Example 22 in which the shutdown part and the protective tape are arranged in all parts are 1000 The battery thickness was measured one by one, and the average of the battery thickness was determined.

  Table 2 below shows the measurement results.

  Further, the battery thicknesses of Example 1 and Comparative Example 19, Example 2 and Comparative Example 20, Example 3 and Comparative Example 21, Comparative Example 1 and Comparative Example 18, Comparative Example 2 and Comparative Example 22 having the same separator thickness were used. The battery thickness reduction rate was measured.

  Table 3 below shows the measurement results.

  Here, in Comparative Example 1 and Comparative Example 18 in which the separator thickness was 0.7 μm, internal short circuit occurred frequently, and the battery could not be manufactured.

  From the above results, it can be seen that the battery provided with the shutdown portion can reduce the battery thickness by about 2% as compared with the battery using the conventional protective tape.

(V) Measurement of battery capacity deterioration rate For each battery used in the above measurement (iV), charging was performed at a constant voltage and a constant current for 3 hours at a charging voltage of 4.2 V and a charging current of 700 mA, and then discharging at 1 C was performed. The discharge was terminated when the voltage reached 3.0 V, and the battery capacity at this time was measured. Next, after repeating this charge / discharge cycle 100 cycles, the battery capacity was measured again, and the battery capacity deterioration rate [%] was measured by the following formula.

  Battery capacity deterioration rate [%] = {(battery capacity at the first cycle) − (battery capacity at the 100th cycle)} / (battery capacity at the first cycle) × 100

  Table 4 below shows the measurement results.

  Here, as in the measurement (iV), when the separator thickness was 0.7 μm, internal short circuit occurred frequently, and the battery could not be manufactured.

  From the above results, it can be seen that when the separator thickness is 12 μm, the battery capacity is greatly deteriorated regardless of the use of the shutdown separator and the protective tape.

  Thus, from the above measurements (iii) to (V), by using a separator having a thickness of 1 μm or more and 9 μm or less having a shutdown portion with a puncture strength of 250 gf or more and a porosity of 20% or less. It can be seen that a high-quality non-aqueous electrolyte battery that prevents a short circuit inside the battery, can be reduced in thickness, and suppresses deterioration of the battery capacity can be produced.

  Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. .

  For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

  In addition, pressure inside the battery, such as external pressure required in the manufacturing process and battery temperature rise, may increase the pressure inside the battery, and breakage of the separator due to the electrode end or active material application end, electrode contact, etc. Any battery can achieve the effect by applying the present invention. The battery element is not limited to a wound type, and can be used in any case such as a bent type in which an electrode is bent. Moreover, it is not restricted to a secondary battery, If it is a battery which has the above structures, it can be applied also to a primary battery.

  In addition, this time, the method of pressurizing and heating the separator was used for shutting down the separator. However, if the shutdown portion can be provided so that the puncture strength of the shutdown portion is 250 gf or more and the porosity is 20% or less. It is not limited to the method.

It is sectional drawing of the battery element using a protective tape like the past. It is a schematic diagram which shows an example of a structure of the nonaqueous electrolyte battery to which this invention is applied. It is a schematic diagram which shows an example of a structure of the battery element of the nonaqueous electrolyte battery to which this invention is applied. It is a schematic diagram which shows an example of the winding process of the battery element of the nonaqueous electrolyte battery to which this invention is applied. It is sectional drawing of the battery element of the nonaqueous electrolyte battery to which this invention is applied. It is a graph which shows the relationship between the puncture intensity | strength of the shutdown part of a separator, and a battery internal short circuit incidence. It is a graph which shows the relationship between the porosity of the shutdown part of a separator, and a battery internal short circuit incidence.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 ... Positive electrode 1a, 11a Positive electrode active material layer 1b, 11b ... Positive electrode collector 2,12 ... Negative electrode 2a, 12a ... Negative electrode active material layer 2b, 12b ... Negative electrode current collector Body 3a, 3b, 13a, 13b ... Separator 5a, 15a ... Positive electrode terminal 5b, 15b ... Negative electrode terminal 6a, 6b, 6c, 6d, 6e, 6f ... Insulating coating material 10 ... Nonaqueous electrolyte battery 16a, 16b ... sealant 17a, 17b, 17c, 17d ... shutdown part 18 ... laminate film 18a ... battery element housing part 20 ... battery element 21 ... element winding Part 22 ... Separator heat treatment part 23 ... Core

Claims (6)

A non-aqueous electrolyte having a battery element in which a positive electrode in which a positive electrode active material is applied on a positive electrode current collector and a negative electrode in which a negative electrode active material is applied on a negative electrode current collector are stacked and wound via a separator In batteries,
In a portion where the end portion of one of the electrodes faces the other electrode through the separator, a shutdown portion in which the separator is shut down is provided on the separator adjacent to the end portion of the one electrode. Non-aqueous electrolyte battery. In the portion where the end of the positive electrode faces the negative electrode through the separator, the shutdown portion is provided on the separator,
In the portion where the end of the negative electrode faces the positive electrode via the separator, the shutdown portion is provided on the separator,
The nonaqueous electrolyte battery according to claim 1, wherein a coating end portion of the positive electrode active material and the negative electrode active material is covered.   The nonaqueous electrolyte battery according to claim 1, wherein a gel-like or plastic electrolyte is applied to both surfaces of the positive electrode and the negative electrode.   The nonaqueous electrolyte battery according to claim 1, wherein the separator is made of polyethylene.   The nonaqueous electrolyte battery according to claim 1, wherein the separator has a thickness of 1 μm to 9 μm.   2. The nonaqueous electrolyte battery according to claim 1, wherein the puncture strength of the shutdown portion is 250 gf or more and the porosity is 20% or less.

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