JP2005063855A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery capable of improving safety in overcharge without impairing energy density. <P>SOLUTION: This nonaqueous electrolyte secondary battery is provided with: an electrode group 2 composed by rolling a positive electrode 5 and a negative electrode 6 into a flat shape by interlaying a separator 7 so as to set the separator 7 in the outermost circumference; an electrode lead having one end electrically connected to the positive electrode 5 or the negative electrode 6, and the other end extracted from one-side spiral surface of the electrode group 2; and a vessel 1 made of a laminate film for housing the electrode group 2. The battery is characterized by that the inside surface of the vessel 1 is formed of a thermoplastic resin layer of the laminate film; and a heat-resistant insulation layer 11 is formed at least in a part facing to the other-side spiral surface of the electrode group 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

  In recent years, electronic devices such as mobile communication devices, notebook computers, palmtop computers, integrated video cameras, portable CD (MD) players, cordless telephones, etc. have been reduced in size and weight. As a power source, a battery having a small size and a large capacity is particularly demanded.

  Examples of batteries that are widely used as power sources for these electronic devices include primary batteries such as alkaline manganese batteries, and secondary batteries such as nickel cadmium batteries and lead storage batteries. Among these, non-aqueous electrolyte secondary batteries that use lithium composite oxide for the positive electrode and carbonaceous materials that can occlude and release lithium ions for the negative electrode are small and light, have high unit cell voltage, and have high energy density. Is attracting attention.

  In recent years, as a container for storing an electrode group including a positive electrode and a negative electrode as described above, a laminate film obtained by bonding a metal foil such as aluminum and a resin and molded into a bag shape or a cup shape is used. As a result, the weight and size of the nonaqueous electrolyte secondary battery can be further reduced.

  However, the secondary battery having such a configuration is not sufficiently safe at the time of abnormal overcharging due to a failure of the charger or the like. That is, when an electrolyte decomposition reaction occurs due to overcharging, the temperature is increased to block the pores of the separator, thereby suppressing the reaction and ensuring the safety. However, the reaction is completely stopped. It is difficult. Therefore, when the overcharged state continues for a long time, the reaction gradually proceeds and the temperature rises, so that the resin on the inner surface of the laminate film melts and the metal foil is exposed, and with the thermal contraction of the separator The end of the positive electrode or the negative electrode protrudes from the surface of the electrode group, and a short circuit occurs due to contact between the protruding end and the metal foil, and heat is generated.

  In Japanese Patent Laid-Open No. 11-329506, an oxide film 20 is provided between the metal layer 16 of the laminate film and the heat fusion layer 17, so that when the laminate film is welded, the resin layer 17 is thermally melted. And preventing the metal layer 16 from contacting each other.

However, when the oxide film 20 is provided between the metal layer 16 and the heat sealing layer 17, the battery thickness increases with an increase in the thickness of the laminate film, which causes a problem that the energy density of the battery decreases.
JP 11-329506 A (Claims, FIG. 3)

  An object of this invention is to provide the nonaqueous electrolyte secondary battery which can improve the safety | security at the time of an overcharge, without impairing energy density.

The non-aqueous electrolyte secondary battery according to the present invention includes an electrode group in which a positive electrode and a negative electrode are wound in a flat shape so that the outermost periphery becomes a separator with a separator interposed therebetween,
An electrode lead having one end electrically connected to the positive electrode or the negative electrode and the other end drawn from one spiral surface of the electrode group;
A non-aqueous electrolyte secondary battery comprising a laminate film container in which the electrode group is housed,
An inner surface of the container is formed from a thermoplastic resin layer of the laminate film, and a heat-resistant insulating layer is formed at least on a portion of the inner surface facing the other spiral surface of the electrode group. It is characterized by this.

  ADVANTAGE OF THE INVENTION According to this invention, the non-aqueous electrolyte secondary battery of the high energy density excellent in the safety | security at the time of overcharge can be provided.

  A nonaqueous electrolyte secondary battery according to the present invention will be described with reference to FIGS.

  In the container 1, after a part of the laminate film is molded into a cup shape, the electrode group 2 is stored in the cup-shaped storage portion, and the positive electrode lead 3 and the negative electrode lead 4 electrically connected to the electrode group 2 are externally connected. It can be obtained by applying a heat seal in the state pulled out. The electrode group 2 has a structure in which a laminate including a positive electrode 5, a negative electrode 6, and a separator 7 disposed between the positive electrode 5 and the negative electrode 6 is wound into a flat shape. The outermost periphery of the electrode group 2 is a separator 7. The positive electrode 5 includes a positive electrode current collector 5a and a positive electrode layer 5b formed on the positive electrode current collector 5a. On the other hand, the negative electrode 6 includes a negative electrode current collector 6a and a negative electrode layer 6b formed on the negative electrode current collector 6a. The nonaqueous electrolyte is held in the electrode group 2. The electrode group 2 may not be pressed, but may be pressed to increase the integrated strength of the positive electrode 5, the negative electrode 6 and the separator 7. It is also possible to heat at the time of pressing. The electrode group 2 can contain an adhesive polymer in order to increase the integrated strength of the positive electrode 5, the negative electrode 6 and the separator 7. Examples of the adhesive polymer include polyacrylonitrile (PAN), polyacrylate (PMMA), polyvinylidene fluoride (PVdF), polyvinyl chloride (PVC), and polyethylene oxide (PEO). .

  The laminate film comprises an outer protective layer 8 constituting the outer surface of the container, an inner protective layer 9 made of a thermoplastic resin that forms the inner surface of the container, and a metal layer 10 disposed between the outer protective layer 8 and the inner protective layer 9. including. One end of the positive electrode lead 3 is electrically connected to the positive electrode current collector 5a, and the other end is drawn out from one spiral surface of the electrode group 2 to the outside of the container 1 and serves as a positive electrode terminal. On the other hand, one end of the negative electrode lead 4 is electrically connected to the negative electrode current collector 6 a and the other end is drawn out of the same spiral surface as the positive electrode lead 3 to the outside of the container 1 and serves as a negative electrode terminal.

  As shown in FIG. 2, the heat-resistant insulating layer 11 is formed on the inner surface portion facing the other spiral surface of the electrode group 2 (the spiral surface from which the positive electrode lead 3 and the negative electrode lead 4 are not drawn). .

  According to such a secondary battery, when the overcharged state continues for a long time due to a failure of a charger of a portable device incorporating the secondary battery and the battery temperature rises, the inner protective layer 9 is melted. Although the heat shrinkage of the separator 7 occurs, the heat-resistant insulating layer 11 can maintain insulation between the other spiral surface of the electrode group 2 and the metal layer 10 in the laminate film, so that heat generation due to a short circuit can be prevented and dangers such as ignition Can be avoided. Since the heat-resistant insulating layer 11 is formed only on the inner surface portion facing the spiral surface of the electrode group 2, the formation of the heat-resistant insulating layer 11 does not increase the battery thickness. Since the thickness is only partially increased, the processability of the laminate film is not impaired.

  Furthermore, according to the present invention, even when a thermoplastic resin having a low melting point such as polyethylene is used for the internal protective layer of the laminate film, safety during overcharge can be ensured. It becomes possible to use a solvent having a property.

  In addition, about the spiral surface from which the positive electrode lead 3 and the negative electrode lead 4 of the electrode group 2 are drawn, the space provided between the inner surface of the container is large due to the presence of the positive electrode lead 3 and the negative electrode lead 4. 7 is not easily short-circuited even if the heat shrinkage of 7 and melting of the internal protective layer 9 occur, but in order to obtain higher safety, the spiral surface from which the positive and negative electrode leads 3 and 4 are drawn as shown in FIG. It is desirable to form the heat-resistant insulating layer 11 on the inner surface portion facing the surface.

  Hereinafter, the positive electrode, the negative electrode, the separator, the nonaqueous electrolyte, the laminate film, and the heat resistant insulating layer will be described.

1) Positive electrode The positive electrode includes a current collector and a positive electrode layer that is supported on the current collector and includes an active material. The positive electrode layer may be formed on both surfaces of the current collector as shown in FIGS. 1 to 3 described above, or may be formed only on one surface of the current collector.

  The positive electrode layer includes a positive electrode active material, a binder, and a conductive agent.

Examples of the positive electrode active material include various oxides such as manganese dioxide, lithium manganese composite oxide, lithium-containing nickel oxide, lithium-containing cobalt oxide, lithium-containing nickel cobalt oxide, lithium-containing iron oxide, and lithium. Examples thereof include vanadium oxide and chalcogen compounds such as titanium disulfide and molybdenum disulfide. Among them, when a lithium-containing cobalt oxide (for example, LiCoO ₂ ), a lithium-containing nickel cobalt oxide (for example, LiNi _0.8 Co _0.2 O ₂ ), or a lithium manganese composite oxide (for example, LiMn ₂ O ₄ , LiMnO ₂ ) is used. This is preferable because a high voltage can be obtained. As the positive electrode active material, one kind of oxide may be used alone, or two or more kinds of oxides may be mixed and used.

  Examples of the conductive agent include acetylene black, carbon black, and graphite.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyether sulfone, ethylene-propylene-diene copolymer (EPDM), and styrene-butadiene rubber (SBR). Can be used.

  The mixing ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.

  As the current collector, a conductive substrate having a porous structure or a non-porous conductive substrate can be used. These conductive substrates can be formed from, for example, aluminum, stainless steel, or nickel.

  The positive electrode is produced, for example, by suspending a conductive agent and a binder in an appropriate solvent in a positive electrode active material, applying the suspension to a current collector, and drying to form a thin plate.

2) Negative electrode The negative electrode includes a current collector and a negative electrode layer carried on the current collector. The negative electrode layer may be formed on both sides of the current collector as shown in FIGS. 1 to 3 described above, but may be formed only on one side of the current collector.

  The negative electrode layer includes a negative electrode active material that absorbs and releases lithium ions and a binder.

Examples of the negative electrode active material include graphite materials, carbonaceous materials such as graphite, coke, carbon fiber, spherical carbon, pyrolytic gas phase carbonaceous material, and resin fired body; thermosetting resin, isotropic pitch, mesophase Graphite material obtained by subjecting pitch-based carbon, mesophase pitch-based carbon fiber, mesophase microspheres, etc. (especially mesophase pitch-based carbon fiber is preferable because of its high capacity and charge / discharge cycle characteristics) to 500-3000 ° C. Or a carbonaceous material; a chalcogen compound such as titanium disulfide, molybdenum disulfide, or niobium selenide; a light metal such as aluminum, an aluminum alloy, a magnesium alloy, lithium, or a lithium alloy; Among them, it is preferable to use a graphite material having a graphite crystal having a (002) plane spacing _d002 of 0.34 nm or less. A nonaqueous electrolyte secondary battery provided with a negative electrode containing such a graphite material as a negative electrode active material can greatly improve battery capacity and large current discharge characteristics. More preferably, the surface interval _d002 is 0.337 nm or less.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and the like. Can be used.

  The blending ratio of the negative electrode active material and the binder is preferably in the range of 90 to 98% by weight of the carbonaceous material and 2 to 20% by weight of the binder.

  As the current collector, a conductive substrate having a porous structure or a non-porous conductive substrate can be used. These conductive substrates can be formed from, for example, copper, stainless steel, or nickel.

  The negative electrode is prepared by, for example, kneading a negative electrode active material and a binder in the presence of a solvent, applying the obtained suspension to a current collector, drying it, and then pressing it once at a desired pressure or 2 It is produced by multi-stage pressing ˜5 times.

3) Separator As this separator, a microporous film, a woven fabric, a non-woven fabric, a laminate of the same material or different materials among these can be used. In particular, the microporous membrane causes a so-called shutdown phenomenon in which the resin constituting the separator plastically deforms and closes the fine pores when the temperature of the electrode group rises abnormally due to heat generated by overcharging, etc., and the flow of lithium ions Is prevented, and further overheating is prevented, and the overcharge state can be safely terminated, which is preferable. Examples of the material for forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-butene copolymer. As a material for forming the separator, one type or two or more types selected from the types described above can be used.

4) Non-aqueous electrolyte The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte (for example, lithium salt) dissolved in the non-aqueous solvent. The form of the non-aqueous electrolyte can be liquid (non-aqueous electrolyte) or gel.

  Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone ( γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. The non-aqueous solvent may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoromethane. A lithium salt such as lithium sulfonate (LiCF ₃ SO ₃ ) can be given. The electrolytes may be used alone or in combination of two or more. The amount of the electrolyte dissolved in the non-aqueous solvent is preferably 0.2 mol / l to 2 mol / l.

  The non-aqueous solvent can contain at least one kind of halogenated toluene selected from the group consisting of toluene chloride (CT) and orthofluorinated toluene (o-FT). Toluene halide is added to make the shutdown of the separator more reliable.

  The non-aqueous solvent may contain a surfactant such as trioctyl phosphate (TOP) in order to improve the wettability with the separator. The addition amount of the surfactant is preferably 3% or less, and more preferably in the range of 0.1 to 1%.

  In the non-aqueous solvent, the following solvents can be contained as subcomponents.

  Examples of the auxiliary component include vinylene carbonate, vinyl ethylene carbonate, phenyl ethylene carbonate, γ-valerolactone, methyl propionate, ethyl propionate, 2-methylfuran, furan, thiophene, catechol carbonate, ethylene sulfite, and 12-crown. -4, tetraethylene glycol dimethyl ether and the like.

  The amount of the non-aqueous electrolyte is preferably 0.2 to 0.6 g per 100 mAh of battery unit capacity. A more preferable range of the amount of the nonaqueous electrolytic solution is 0.25 to 0.55 g / 100 mAh.

5) Laminate film The internal protective layer may be formed of a thermoplastic resin layer as shown in FIG. 1 described above, but a multilayer structure comprising a thermoplastic resin layer constituting the inner surface of the container and other types of resin layers. It may also have.

  A thermoplastic resin layer can be formed from polyolefin resin, such as polyethylene and a polypropylene, for example. Among them, polyethylene is most suitable when a non-aqueous electrolyte containing halogenated toluene is used because it has high corrosion resistance against halogenated toluene.

  The metal layer can be formed from, for example, aluminum or an aluminum alloy.

  The external protective layer can be formed from, for example, a polyolefin resin such as polyethylene or polypropylene, or polyethylene terephthalate.

  In FIG. 1 described above, an example in which a laminate film composed of an external protective layer, a metal layer, and an internal protective layer is used has been described.

6) Heat-resistant insulating layer The heat-resistant insulating layer can be formed, for example, by attaching a resin tape made of a resin such as polyimide or polyethylene terephthalate to the inner surface of the laminate film. The heat resistant temperature of the resin tape is preferably 150 ° C. or higher.

The heat-resistant insulating layer is formed by applying and drying paint on the inner surface of the laminate film, in which an inorganic filler such as Al ₂ O ₃ (heat-resistant insulating material) is dissolved in a solvent together with a binder such as polyvinylidene fluoride (PVdF). I can do it. As a method of application, a general application method such as spraying can be used.

  Among these, application of a heat-resistant insulating material is preferable because it becomes easy to form a heat-resistant insulating layer after the laminate film is formed into a cup shape.

  The thickness of the heat-resistant insulating layer is desirably in the range of 10 to 50 μm. This is because if the thickness of the heat-resistant insulating layer is less than 10 μm, the insulation between the laminate film and the electrode group may be insufficient, and it is preferable to increase the thickness of the heat-resistant insulating layer in order to improve the insulating property. This is because if the thickness of the heat-resistant insulating layer exceeds 50 μm, the energy density of the battery may be greatly affected.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Example 1)
<Preparation of positive electrode>
First, 90% by weight of lithium cobalt oxide (Li _x CoO ₂ ; X is 0 <X ≦ 1) powder, 5% by weight of acetylene black, and 5% by weight of polyvinylidene fluoride (PVdF) dimethylformamide (DMF) solution was added and mixed to prepare a slurry. The slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 μm, then dried and pressed to produce a positive electrode having a structure in which the positive electrode layer was supported on both sides of the current collector. The thickness of the positive electrode layer was 60 μm per side.

<Production of negative electrode>
As a carbonaceous material, 95% by weight of powder of mesophase pitch-based carbon fiber (having a (002) plane interval (d ₀₀₂ ) of 0.336 nm determined by powder X-ray diffraction) heat-treated at 3000 ° C. and polyvinylidene fluoride ( (PVdF) 5% by weight dimethylformamide (DMF) solution was mixed to prepare a slurry. The slurry was applied to both surfaces of a current collector made of a copper foil having a thickness of 12 μm, dried, and pressed to prepare a negative electrode having a structure in which the negative electrode layer was supported on the current collector. The thickness of the negative electrode layer was 55 μm per side.

The surface spacing d ₀₀₂ of (002) plane of the carbonaceous material were respectively determined by the powder X-ray diffraction spectrum half width midpoint method. At this time, scattering correction such as Lorentz scattering was not performed.

<Separator>
A separator made of a microporous polyethylene film having a thickness of 25 μm and a porosity of 45% was prepared.

<Production of electrode group>
After the positive electrode lead made of a strip-shaped aluminum foil (thickness 100 μm) is ultrasonically welded to the positive electrode current collector, and the negative electrode lead made of a strip-shaped nickel foil (thickness 100 μm) is ultrasonically welded The positive electrode and the negative electrode were spirally wound with the separator interposed therebetween so that the outermost periphery became the separator, thereby preparing an electrode group. The electrode group was formed into a flat shape by applying pressure with a press while heating.

<Preparation of heat-resistant insulating layer>
A 100 μm thick laminated film with both sides of an aluminum foil covered with polyethylene is formed into a rectangular cup shape by a press machine, and then a 30 μm thick polyimide tape is applied to the inner surface of each of the spiral surfaces of the electrode group. A heat-resistant insulating layer was formed. The electrode group was housed in the obtained container so that both spiral surfaces face the heat-resistant insulating layer.

  Next, the electrode group in the container was vacuum dried at 80 ° C. for 12 hours to remove moisture contained in the electrode group and the laminate film.

<Preparation of non-aqueous electrolyte>
A nonaqueous solvent was prepared by mixing ethylene carbonate (EC), γ-butyrolactone (GBL), and orthochlorotoluene so that the weight ratio (EC: GBL: o-CT) was 35: 60: 5. Lithium tetrafluoroborate (LiBF ₄ ) was dissolved in the obtained non-aqueous solvent so that its concentration was 1.5 mol / L to prepare a non-aqueous electrolyte.

  After injecting the non-aqueous electrolyte into the electrode group in the container so that the amount per battery capacity 1Ah is 4.8 g and sealing by heat sealing, the structure shown in FIGS. A nonaqueous electrolyte secondary battery having a thickness of 3.6 mm, a width of 35 mm, a height of 62 mm, and a nominal capacity of 0.65 Ah was assembled.

  The following treatment was applied to the non-aqueous electrolyte secondary battery as an initial charge / discharge process. First, constant current / constant voltage charging was performed for 15 hours at room temperature to 4.2 V at 0.2C. Then, it discharged to 3.0V at 0.2C at room temperature, and manufactured the nonaqueous electrolyte secondary battery.

  Here, 1C is a current value necessary for discharging the nominal capacity (Ah) in one hour. Therefore, 0.2 C is a current value necessary for discharging the nominal capacity (Ah) in 5 hours.

(Example 2)
A 100 μm thick laminated film with both sides of aluminum foil covered with polyethylene is formed into a rectangular cup shape with a press machine, and then Al ₂ O ₃ and PVdF are weighted on the inner surface facing both spiral surfaces of the electrode group. A non-aqueous electrolyte was applied in the same manner as in Example 1 except that a paint dissolved in n-methylpyrrolidone was applied by spray so as to have a ratio of 40:60 and then dried to form a heat-resistant insulating layer having a thickness of 10 μm. A secondary battery was manufactured.

(Comparative Example 1)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the heat resistant insulating layer was not formed on the laminate film.

(Comparative Example 2)
The same kind of paint as described in Example 2 was applied to one surface of the aluminum foil and dried to form a heat-resistant insulating film having a thickness of 10 μm. A laminate film having a thickness of 110 μm was produced by forming polyethylene layers on both sides of the aluminum foil. A nonaqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 except that this laminate film was used without forming a heat-resistant insulating layer.

  An overcharge test was performed on 10 pieces of each of the obtained nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 and 2. The overcharge test method records the number of non-aqueous electrolyte secondary batteries that continue to be charged at a current value of 3 C, and then generate abnormal heat generation or ignition. The test results are shown in Table 1 below.

The weight energy density of each secondary battery is also shown in Table 1 below.

  As is clear from Table 1, the secondary batteries of Examples 1 and 2 using a container in which a heat-resistant insulating layer is formed on the inner surface facing the spiral surface from which the positive and negative electrode leads are not drawn out are the heat-resistant insulating layer. It can be understood that the abnormal heat generation and ignition at the time of overcharge were eliminated while realizing the energy density equivalent to that in the case of using the container in which no is formed (Comparative Example 1).

  On the other hand, in the secondary battery of Comparative Example 1 using a container in which the heat-resistant insulating layer was not formed, abnormal heat generation or ignition occurred in half of the ten batteries. On the other hand, the secondary battery of Comparative Example 2 in which a heat-resistant insulating film was formed between the metal layer of the laminate film and the thermoplastic resin layer had no abnormal heat generation or ignition during overcharge, but the energy density was implemented. It was low compared with Examples 1-2.

  The present invention is not limited to the above-described embodiments, and can be similarly applied to combinations of other types of positive electrode, negative electrode, separator, and electrolyte.

The perspective view which shows the thin lithium ion secondary battery which is one Embodiment of the nonaqueous electrolyte secondary battery concerning this invention. The fragmentary sectional view which shows the spiral surface from which the electrode lead is not pulled out among the cross sections which cut | disconnected the thin lithium ion secondary battery of FIG. 1 along the long side direction. The fragmentary sectional view which shows the spiral surface from which the electrode lead is pulled out among the cross sections which cut | disconnected the thin lithium ion secondary battery of FIG. 1 along the long side direction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Electrode group, 3 ... Positive electrode lead, 4 ... Negative electrode lead, 5 ... Positive electrode, 5a ... Positive electrode collector, 5b ... Positive electrode layer, 6 ... Negative electrode, 6a ... Negative electrode collector, 6b ... Negative electrode layer , 7 ... separator, 8 ... external protective layer, 9 ... internal protective layer, 10 ... metal layer, 11 ... heat-resistant insulating layer.

Claims (3)

A group of electrodes wound in a flat shape so that the outermost periphery becomes a separator with a separator interposed between a positive electrode and a negative electrode;
An electrode lead having one end electrically connected to the positive electrode or the negative electrode and the other end drawn from one spiral surface of the electrode group;
A non-aqueous electrolyte secondary battery comprising a laminate film container in which the electrode group is housed,
An inner surface of the container is formed from a thermoplastic resin layer of the laminate film, and a heat-resistant insulating layer is formed at least on a portion of the inner surface facing the other spiral surface of the electrode group. A non-aqueous electrolyte secondary battery.   The nonaqueous electrolyte secondary battery according to claim 1, wherein a thickness of the heat resistant insulating layer is in a range of 10 to 50 μm.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the heat-resistant insulating layer is a heat-resistant resin tape or is formed by coating with a heat-resistant insulating material.

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