JP2012195314A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which increases in internal resistance when an abnormality occurs.SOLUTION: In the nonaqueous electrolyte secondary battery, at least one of the surface and the interior of at least one layer selected from the group consisting of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, contains a gas generating agent, the electrolyte layer includes a separator and an electrolytic solution, and a sealing portion is disposed at least around the positive electrode active material layer and the negative electrode active material layer. When the temperature of the secondary battery reaches a temperature equal to or higher than 60°C and lower than 300°C, the gas generating agent generates a gas.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a non-aqueous electrolyte secondary battery whose internal resistance increases when an abnormality occurs.

  Non-aqueous electrolyte secondary batteries are widely used as power sources for various electronic devices and mobile objects. However, the non-aqueous electrolyte secondary battery may generate heat due to internal defects or external factors.

  Patent Document 1 discloses a secondary battery in which a compound that generates gas at 300 to 600 ° C. (hereinafter referred to as “gas generating agent”) is added to a negative electrode or a separator in order to suppress thermal runaway due to self-heating. Has been.

JP 200526080 A

  According to Patent Document 1, a gas generating agent is used in order to prevent the molten positive electrode from coming into contact with the negative electrode. However, even if the contact between the molten positive electrode and the negative electrode is suppressed, the battery temperature may continue to rise and thermal runaway may proceed unless the internal resistance is increased. If the thermal runaway progresses, the battery will explode and the electrolyte may splatter or ignite, causing damage to external equipment or a fire.

  Furthermore, according to Patent Document 1, if the gas generating agent is thermally decomposed at a temperature lower than 300 ° C., the normal use of the battery is adversely affected. However, even if the temperature is less than 300 ° C., the amount of current that can flow is increased as the temperature rises. Therefore, if the internal resistance of the secondary battery does not increase, the secondary battery is transferred to an external device. An overcurrent may flow and damage an external device that is more expensive than the secondary battery. Further, depending on the structure of the nonaqueous electrolyte secondary battery, the temperature of the thermal runaway may be reached even at a temperature lower than 300 ° C.

  When there is a risk of causing thermal runaway or overcharge, it is desirable to prioritize suppression of fire and damage to external equipment over battery function. Therefore, an object of the present invention is to provide a non-aqueous electrolyte secondary battery in which internal resistance increases when an abnormality occurs and thermal runaway and overcharge can be suppressed.

  In view of the above problems, the present inventors have conducted extensive research, and as a result, the surface of at least one layer selected from the group consisting of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer of a nonaqueous electrolyte secondary battery. Alternatively, by including a gas generating agent inside, when the temperature of the nonaqueous electrolyte secondary battery rises, gas is generated from the gas generating agent, and the gas is a positive electrode active material layer, a separator, a negative electrode active material layer, etc. Of the secondary battery by increasing or decreasing the internal resistance of the secondary battery by narrowing or blocking the movement path of ions traveling between the positive electrode active material layer and the negative electrode active material layer. It has been found that further temperature rise and generation of overcurrent are suppressed, and the present invention has been completed.

  That is, the present invention includes a gas generating agent on the surface or inside of at least one layer selected from the group consisting of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, and the electrolyte layer includes a separator and an electrolyte solution. In addition, a seal is disposed at least around the positive electrode active material layer and the negative electrode active material layer, and gas is generated from the gas generating agent when the temperature of the secondary battery reaches 60 ° C. or higher and lower than 300 ° C. This is a non-aqueous electrolyte secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, internal resistance increases at the time of abnormality occurrence, and the nonaqueous electrolyte secondary battery which can suppress a thermal runaway and an overcurrent can be provided.

It is the cross-sectional schematic of the single battery layer pinched | interposed into a pair of electrical power collector. It is the cross-sectional schematic which shows the example of arrangement | positioning of a seal part, A shows the example by which the seal part between collectors is arrange | positioned, B shows the example by which the seal part was arrange | positioned between an electrical power collector and an electrolyte layer. Show. 1 is a schematic cross-sectional view showing an example of a bipolar nonaqueous electrolyte secondary battery. 1 is a schematic cross-sectional view showing an example of a non-bipolar non-aqueous electrolyte secondary battery. 1 is a partial cross-sectional schematic view of a wound nonaqueous electrolyte secondary battery according to an embodiment of the present invention. 1 is a partial cross-sectional schematic view of a multilayer nonaqueous electrolyte secondary battery according to an embodiment of the present invention.

  The first of the present invention includes a gas generating agent on the surface or inside of at least one layer selected from the group consisting of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, and the temperature of the secondary battery is 60 ° C. or higher. The non-aqueous electrolyte secondary battery is characterized in that gas is generated from the gas generating agent when the temperature reaches less than 300 ° C.

  When a gas is generated from a gas generating agent contained in the surface or inside of at least one layer selected from the group consisting of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, the gas narrows the ion migration path or Blocking causes a decrease in the amount of ion movement or stop of movement. Accordingly, the internal resistance of the secondary battery increases, and the operation of the secondary battery is suppressed or stopped, and overcurrent or thermal runaway can be suppressed.

  Hereinafter, the nonaqueous electrolyte secondary battery components of the present invention will be described in detail.

[Negative electrode active material layer]
The negative electrode active material layer includes a negative electrode active material that releases ions during discharge and can store ions during charge. Examples of the negative electrode active material include a metal oxide such as TiO, Ti ₂ O ₃ , TiO ₂ , or SnO ₂ , and a composite of lithium and a transition metal such as Li _4/3 Ti _5/3 O ₄ or Li ₇ MnN. Preferred examples include oxides, Li—Pb alloys, Li—Al alloys, Li, or carbon materials such as natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, or hard carbon. Can be used alone or in admixture of two or more.

  The negative electrode active material layer can contain a conductive additive, a binder, an electrolyte, or the like depending on the purpose. Examples of the conductive aid include acetylene black, carbon black, or graphite. Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride (hereinafter also referred to as “PVdF”), and the like. Details of the electrolyte are described in the section of the electrolyte layer described later.

  In the present invention, the negative electrode active material layer can contain a gas generating agent. The gas generating agent can be disposed on the surface of the negative electrode active material layer or inside the negative electrode active material layer. Details of the gas generating agent will be described later in the section of the gas generating agent.

[Positive electrode active material layer]
The positive electrode active material layer includes a positive electrode active material that can occlude ions during discharge and release ions during charge. Preferred examples of the positive electrode active material include composite oxides of lithium and transition metals, transition metal oxides, transition metal sulfides, PbO ₂ , AgO, or NiOOH. These may be used alone or in combination of two or more. Even it can be used.

Examples of the composite oxide of lithium and transition metal include Li-Mn based composite oxides such as LiMnO ₂ and LiMn ₂ O ₄ , Li—Co based composite oxides such as LiCoO _2, and Li— such as LiNiO _2. Preferable examples include Ni-based composite oxides, Li—Fe-based composite oxides such as LiFeO ₂ , composite phosphate compounds of lithium and transition metals such as LiFePO ₄ , and composite sulfate compounds of lithium and transition metals. Preferred examples of the transition metal oxide include V ₂ O ₅ , MnO ₂ , V ₂ MoO ₈ , and MoO ₃ . Preferred examples of the transition metal sulfide include TiS _{2 and} MoS ₂ . These positive electrode active materials can be used alone or in admixture of two or more.

  The positive electrode active material layer can contain the above-described conductive additive, the above-mentioned binder, the electrolyte described later, or the like depending on the purpose.

  In the present invention, the positive electrode active material layer may contain a gas generating agent. The gas generating agent can be disposed on the surface of the positive electrode active material layer or inside the positive electrode active material layer. Details of the gas generating agent will be described later in the section of the gas generating agent.

  The positive electrode active material layer and the negative electrode active material layer may contain other materials if necessary. For example, an ion conductive polymer may be included. When an ion conductive polymer is included, a polymerization initiator for polymerizing the polymer may be included.

  Examples of the ion conductive polymer include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers. Here, the polymer may be the same as or different from the ion conductive polymer used in the electrolyte layer of the nonaqueous electrolyte secondary battery of the present invention described later, but is preferably the same.

  The polymerization initiator is added to act on the crosslinkable group of the ion conductive polymer to advance the crosslinking reaction. Depending on the external factor for acting as an initiator, it is classified into a photopolymerization initiator, a thermal polymerization initiator and the like. Examples of the polymerization initiator include azobisisobutyronitrile (AIBN), which is a thermal polymerization initiator, and benzyl dimethyl ketal (BDK), which is a photopolymerization initiator.

[Electrolyte layer]
The electrolyte layer electrically insulates the positive electrode active material layer and the negative electrode active material layer, passes ions flowing from the negative electrode active material layer to the positive electrode active material layer during discharging, and charges from the positive electrode active material layer to the negative electrode active material during charging. Pass ions flowing through the layer.

  In the present invention, the electrolyte layer may contain a gas generating agent. The gas generating agent can be disposed on the surface of the electrolyte layer or inside the electrolyte layer. Details of the gas generating agent will be described later in the section of the gas generating agent.

  The electrolyte layer can be classified according to its form into one comprising an electrolytic solution, one comprising a gel electrolyte, or one comprising an intrinsic polymer electrolyte. These details are described below.

[Electrolyte]
The electrolytic solution is a liquid electrolyte, and an electrolytic solution in which a supporting salt is dissolved in a nonaqueous solvent can be used.

  The non-aqueous solvent is not particularly limited, and specific examples thereof include, for example, cyclic carbonates such as propylene carbonate (hereinafter also referred to as “PC”) or ethylene carbonate (hereinafter also referred to as “EC”). Chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, or diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, 1,3- Ethers such as dioxolane or diethyl ether; Lactones such as γ-butyrolactone; Nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; Esters such as methyl acetate and methyl formate Sulfolane; dimethyl sulfoxide; and the like or 3-methyl-1,3-oxazolidin-2-one can be cited preferably, it may be used by alone or in combination with one another.

The supporting salt is not particularly limited, and specific examples thereof include, for example, LiBF ₄ , LiPF ₆ , LiClO ₄ , Li (C ₂ F ₅ SO ₂ ) ₂ N, LiN (SO ₂ CF ₃ ) ₂ , or _{LiN (SO 2 C 2 F 5} ) 2 and the like preferably, it can be used even alone or in combination with one.

  In the case of using an electrolytic solution, it is preferable that a separator be disposed between the positive electrode active material layer and the negative electrode active material layer so that the electrolyte solution and the separator are combined to form an electrolyte layer.

  Although it does not specifically limit as a separator, It is preferable that a thermosetting resin, ceramics, or a thermoplastic resin is included, More preferably, a thermosetting resin or ceramics is included. When the gas is generated, it is preferable that the separator is in a solid state because the gas is easily retained between the electrolyte layer and the positive electrode active material layer or the negative electrode active material layer.

  It is preferable to use a thermosetting resin as the separator because the separator does not melt even when the nonaqueous electrolyte secondary battery becomes high temperature. Although it does not specifically limit as a thermosetting resin, A polyimide, a phenol resin, an epoxy resin, a cellulose, a urea resin, or a melamine resin etc. are mentioned.

It is preferable to use ceramics as the separator because the separator does not melt even when the nonaqueous electrolyte secondary battery becomes high temperature. No particular limitation is imposed on the _{ceramic, Al 2 O 3, ZrO 2} , MgO, BeO, oxide ceramics such as ThO _2, or UO ₂ or _Si 3 _N 4, SiC or non-oxide ceramics such as BN,, Etc.

  Although it does not specifically limit as a thermoplastic resin, Polyolefin, polyamide, or a polyamideimide etc. are mentioned. When a thermoplastic resin is used, the melting point is preferably 300 ° C. or higher, more preferably 500 ° C. or higher. Moreover, although an upper limit is not specifically limited, Preferably it is 1000 degrees C or less.

[Gel electrolyte]
The gel electrolyte is a gel electrolyte in which an electrolytic solution is held in a polymer skeleton in which a three-dimensional network structure is formed by interaction between molecular chains such as chemical bonding, crystallization, or molecular entanglement.

  As the electrolytic solution, those described in the above-mentioned section of the electrolytic solution can be used.

  As the polymer serving as the skeleton, a polymer electrolyte may be used, or a polymer having no ion conductivity may be used. Examples of the polymer electrolyte include an intrinsic polymer electrolyte described later. The polymer not having ion conductivity is not particularly limited, but specific examples thereof include, for example, PVdF, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, copolymers thereof, and alloys thereof. Can be mentioned.

  When a thermoplastic polymer is used, the melting point is preferably 300 ° C. or higher, more preferably 500 ° C. or higher. Moreover, although the upper limit of melting | fusing point is not specifically limited, Preferably it is 1000 degrees C or less. When the gas is generated, it is preferable that the polymer portion is in a solid state because the gas is easily retained between the electrolyte layer and the positive electrode active material layer or the negative electrode active material layer.

[Intrinsic polymer electrolyte]
The intrinsic polymer electrolyte is a solid electrolyte and is distinguished from a gel electrolyte containing an electrolytic solution. When an intrinsic polymer electrolyte is used as the constituent material of the electrolyte layer, since the intrinsic polymer electrolyte does not allow gas to pass through, the gas generated from the gas generating agent remains at the interface between the electrolyte layer and the positive electrode active material layer or the negative electrode active material layer. It is preferable because the effects of the present invention can be exhibited with a small amount of a gas generating agent, and the effects of the present invention can be exhibited in a shorter time.

  The polymer constituting the intrinsic polymer electrolyte is not particularly limited, but specific examples thereof include preferably polyethylene oxide or polypropylene oxide.

  When a thermoplastic material is used as the intrinsic polymer electrolyte, the melting point is preferably 300 to 1000 ° C, more preferably 500 to 1000 ° C. It is preferable that the intrinsic polymer electrolyte is in a solid state at the time of gas generation because gas can be easily retained between the electrolyte layer and the positive electrode active material layer or the negative electrode active material layer.

  In order to improve ionic conductivity, an electrolyte layer may be obtained by adding a supporting salt to an intrinsic polymer electrolyte, or an ionic dissociation group such as a carboxyl group, a phosphate group, a sulfonate group, or a siloxylamine group. May be used as the electrolyte layer. The supporting salt is as described in the above-mentioned section of the electrolytic solution.

  In addition, the electrolyte layer of the present invention may contain a gas generating agent. The gas generating agent can be disposed inside the electrolyte layer or on the surface of the electrolyte layer. Details of the gas generating agent will be described in the section of the gas generating agent described later. Furthermore, the electrolyte layer of the present invention may contain other elements such as resin and ceramics depending on the purpose.

[Gas generating agent]
FIG. 1 shows a single battery layer 10 of a nonaqueous electrolyte secondary battery sandwiched between a pair of current collectors 140. As described above, charging and discharging are performed by ions moving back and forth between the positive electrode active material layer 120 and the negative electrode active material layer 130. However, if ions continue to move when an abnormality occurs, thermal runaway or overcurrent may occur. May flow to external devices.

  When the electrolyte layer 110 includes an electrolyte solution and a separator, the electrolyte solution has permeated into the positive electrode active material layer 120, the separator, and the negative electrode active material layer 130, and ions move in the electrolyte solution. In the present invention, when an abnormality occurs, gas is generated from a gas generating agent (not shown), and the gas enters the pores of the positive electrode active material layer 120, the separator, or the negative electrode active material layer 130, so that the ion movement path is Can be narrowed or blocked. Further, depending on the amount of gas generated, the structure of each layer, etc., gas is accumulated on the contact surface between the separator and the positive electrode active material layer 120 or the negative electrode active material layer 130, and a part or the whole of the interface between these layers is peeled off, It is also possible to narrow or block the ion movement path.

  Further, when the electrolyte layer 110 is made of a gel electrolyte or an intrinsic polymer electrolyte, in the present invention, when an abnormality occurs, gas is generated from a gas generating agent (not shown), and the electrolyte layer 110 and the positive electrode active material layer 120 or the negative electrode active material. Since gas accumulates on the contact surface with the layer 130, a part or the whole of the interface between these layers is peeled off, and the movement of ions is suppressed.

  In the present invention, a substance that generates gas when the temperature of the nonaqueous electrolyte secondary battery reaches 60 ° C. or higher and lower than 300 ° C. is used as the gas generating agent. More preferably, the gas generating agent generates gas at 60 ° C. or higher and 250 ° C. or lower. When the upper limit temperature or storage upper limit temperature of the secondary battery is 60 ° C. or higher and lower than 300 ° C., a substance that generates gas when the temperature rises above the use temperature or storage temperature of the secondary battery is used. In the latter case, it is preferable to use a substance that generates gas when the use upper limit temperature or storage upper limit temperature rises by 10 ° C. or more and 100 ° C. or less. When the use upper limit temperature or storage upper limit temperature rises by 30 ° C. or more and 80 ° C. or less It is more preferable to use a substance that generates gas.

  The gas generated from the gas generating agent preferably contains nitrogen or carbon dioxide. These have very low activity and high safety. The concentration of nitrogen or carbon dioxide in the generated gas is preferably 20 to 100% by volume, more preferably 50 to 100% by volume, and still more preferably 100% by volume. Components other than nitrogen or carbon dioxide vary depending on the gas generating agent.

  Specifically, the gas generating agent is at least one selected from the group consisting of an azide compound, an azo compound, a sulfonyl hydrazide compound, a hydrazine compound, a nitroso compound, a semicarbazide compound, a tetrazole compound, a bicarbonate, and a carbonate. A compound is preferred.

  Examples of the azide compound include sodium azide, calcium azide, lead azide and the like. Examples of the azo compound include azodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate, and the like. Examples of the sulfonyl hydrazide compound include p-toluenesulfonyl hydrazide and p, p'-oxybisbenzenesulfonyl hydrazide. Examples of the hydrazine compound include monomethyl hydrazine. Examples of the nitroso compound include N, N′-dinitrosopentamethylenetetramine, N, N′-dinitroso-N, N′-dimethylterephthalamide and the like. Examples of the semicarbazide compound include p-toluenesulfonyl semicarbazide. Examples of the tetrazole compound include 1H-tetrazole and 5-aminotetrazole. Examples of the bicarbonate include sodium bicarbonate and ammonium bicarbonate. Examples of the carbonate include sodium hydrogen carbonate, ammonium hydrogen carbonate, dimethyl carbonate, and ammonium carbonate. More preferably, the gas generating agent is sodium azide, lead azide, 1H-tetrazole, 5-aminotetrazole, sodium bicarbonate, or dimethyl carbonate. Table 1 below shows the gas generation temperature and generated gas of these gas generating agents.

  The gas generating agent may be included in the capsule. When the gas generating agent is placed in a lump in the nonaqueous electrolyte secondary battery, if the gas generating agent is a powder, liquid, or a brittle substance, the gas generating agent is included in the capsule, The handling of the gas generating agent can be facilitated. However, in the present invention, the form of the gas generating agent is not limited to this. For example, the gas generating agent is arranged so as to be mixed with the components of the nonaqueous electrolyte secondary battery in a powder or liquid state without using a capsule. Also good.

  The material of the capsule is not particularly limited, and specific examples thereof include, for example, polyethylene, polypropylene, vinyl chloride, acrylic resin, nylon (registered trademark), polycarbonate, fluororesin, silicone, styrene rubber, or JP-A-2006. -2134 and the like.

  The gas generating agent may be contained on the surface or inside of at least one layer selected from the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer, and more preferably contained on the surface or inside of the electrolyte layer. .

  The addition amount of the gas generating agent can be appropriately determined depending on the type of the gas generating agent or the target gas generating amount. In the present invention, the amount of gas generated is not particularly limited, but when the gas is generated, the separation distance between the electrolyte layer and the positive electrode active material layer or the negative electrode active material layer may be 0.05 mm to 1 cm. The amount is preferably 0.1 to 5 mm.

  Moreover, when using a separator and electrolyte solution as an electrolyte layer, it is preferable that the addition amount of a gas generating agent is an amount which produces | generates 120-1000 volume% of gas of the void | hole amount of a single cell layer.

[Current collector]
The material of the current collector is not particularly limited, but specific examples include, for example, preferably aluminum, titanium, copper, nickel, silver, or stainless steel, which may be used in a single layer structure. Alternatively, a multilayer structure composed of different kinds of layers may be used, or a clad material coated with these layers may be used. The above materials are excellent in corrosion resistance, conductivity, workability, and the like.

[Seal part]
The nonaqueous electrolyte secondary battery of the present invention may further include a seal portion. The seal part suppresses the gas generated from the gas generating agent from leaking into the gap between the battery element made of the current collector, the positive electrode active material layer, the electrolyte layer, and the negative electrode active material and the exterior enclosing the battery element. To do.

  An arrangement example of the seal portion 250 is shown in A and B of FIG. In the present invention, as shown in FIG. 2A, the seal portion 250 may be disposed between the current collectors 240 so as to surround the single cell layer 20, or as shown in FIG. A seal portion 250 may be disposed between the current collector 240 and the electrolyte layer 210 so as to surround the material layer 220 and the negative electrode active material layer 230, respectively.

  The material of the seal portion is not particularly limited as long as it has an insulating property, but a specific example includes a modified polyolefin.

[Others]
A general separator has high water repellency, and there is a problem that even when a gas generating agent is dissolved and impregnated in a solution, it does not get wet. In this case, impregnation is possible by adding a surfactant. Examples of the surfactant that can be used in this case include tris (2-ethylhexyl) phosphoric acid.

  Depending on the size of the current collector used, a lead or tab may be attached to the current collector. The material of the lead or tab is not particularly limited, and a conventionally known material can be used.

[Construction]
When a plurality of single battery layers are included, the nonaqueous electrolyte secondary battery can take two types of structures, a bipolar type and a non-bipolar type, depending on the arrangement form of the positive electrode active material layer and the negative electrode active material layer. FIG. 3 illustrates a schematic cross-sectional view of a bipolar non-aqueous electrolyte secondary battery, and FIG. 4 illustrates a schematic cross-sectional view of a non-bipolar non-aqueous electrolyte secondary battery. 3, reference numeral 310 indicates an electrolyte layer, reference numeral 320 indicates a positive electrode active material layer, reference numeral 330 indicates a negative electrode active material layer, reference numeral 340 indicates a current collector, and reference numeral 341 indicates a positive electrode side outermost layer current collector. The reference numeral 342 indicates a negative electrode outermost layer current collector, the reference numeral 371 indicates a positive electrode tab, the reference numeral 372 indicates a negative electrode tab, the reference numeral 350 indicates a seal portion, the reference numeral 360 indicates an exterior, and the reference numeral 30 Indicates a cell layer. In FIG. 4, reference numeral 410 indicates an electrolyte layer, reference numeral 420 indicates a positive electrode active material layer, reference numeral 430 indicates a negative electrode active material layer, reference numeral 440 indicates a current collector, reference numeral 442 indicates a lead, and reference numeral 444 indicates A tab is shown and the code | symbol 40 shows a cell layer. 3 and 4 are merely examples, and the thickness, size, ratio, number of layers, and the like of each battery element are not limited to these drawings.

  When the current collector 340 and the end current collector 341 in FIG. 3 and the current collector 440, the lead 420, and the tab 444 in FIG. 4 are seen, the bipolar nonaqueous electrolyte secondary battery (see FIG. 3) is stacked. In contrast to the structure in which power is extracted from the end of the structure, the non-bipolar nonaqueous electrolyte secondary battery (see FIG. 4) has a structure in which power is extracted from each end battery layer. Therefore, further effects can be obtained by applying the present invention to a bipolar secondary battery.

  Then, the manufacturing method of the nonaqueous electrolyte secondary battery of this invention is demonstrated.

  The positive electrode and the negative electrode used in the nonaqueous electrolyte secondary battery of the present invention can be produced by a conventionally known method. For example, an active material slurry is prepared by adding an active material to a solvent (active material Slurry preparation step), coating the active material slurry on the surface of the current collector and drying to form a coating film (coating film forming step), and laminating the laminate prepared through the coating film forming step It can be manufactured by pressing (pressing process). When an ion conductive polymer is added to the active material slurry and a polymerization initiator is further added for the purpose of crosslinking the ion conductive polymer, it is simultaneously with drying in the coating film forming process, or before or after the drying. A polymerization treatment may be performed (polymerization step).

  When the gas generating agent is included in the positive electrode active material layer and / or the negative electrode active material layer, the gas generating agent is preferably applied to the active material slurry so as to have a concentration of 0.01 to 10% by mass. Alternatively, after preparing the battery element described later, a solution containing the gas generating agent is directly dropped onto the positive electrode active material layer or the negative electrode active material layer so that the gas generating agent has a desired amount. Also good.

  When the gas generating agent is contained in the positive electrode active material layer and / or the negative electrode active material layer using the microcapsules containing the gas generating agent as described above, the microcapsules containing the gas generating agent are added to the active material slurry. Alternatively, it may be applied at a concentration of 0.01 to 10% by mass.

The manufacturing method of the microcapsule containing the gas generating agent is not particularly limited, and a conventionally known method can be used. Specific examples thereof include, for example, (1) a dispersion stabilizer such as colloidal silica, water, and an auxiliary stabilizer such as polyvinylpyrrolidone as necessary, which is a production method described in JP-A-2006-2134. (2) an oxygen permeability coefficient of a film having a thickness of 30 to 35 μm made of a homopolymer having a weight average molecular weight of 10,000 to 100,000, such as acrylonitrile, methacrylonitrile, or vinylidene chloride; 0.0 × 10 ⁻¹² cc · cm / cm ² · sec · cm Hg or less, a high gas barrier monomer, 3 to 8 carbon atoms having a carboxyl group such as acrylic acid or methacrylic acid and having a radical polymerizable unsaturated bond Radical polymerizable unsaturated carboxylic acid monomer, dipentaerythritol hexaacrylate and other crosslinking agents A step of dispersing an oily mixture containing a polymerization initiator such as benzoyl and a gas generating agent such as dimethyl carbonate in an aqueous medium; (3) adding a cationic compound such as sodium hydroxide or zinc chloride to the carboxyl A step of reacting a group with a cationic compound; and (4) a step of polymerizing a monomer by pressurizing and heating a reaction vessel.

  The positive electrode and the negative electrode produced as described above are arranged so as to face each other with the electrolyte layer interposed therebetween, thereby forming a single battery layer. Further, in the case of a bipolar battery, a plurality of the single battery layers may be stacked to form a battery stack so that a battery having a desired output can be obtained, or it may be composed of different types of layers. Alternatively, a laminate in which a positive electrode active material layer is formed on one surface of a bipolar current collector and a negative electrode active material layer is formed on the other surface may be laminated with an electrolyte layer interposed therebetween. At the time of lamination, it is preferable to laminate by laminating an insulating film such as a polyimide film having an appropriate thickness while adhering with several places on the surface of the current collector so that the current collectors do not come into contact with each other.

  When the gas generating agent is included in the electrolyte layer, a solution containing the gas generating agent may be directly added dropwise to the electrolyte layer so that the gas generating agent is in a desired amount after producing the battery element. The above-described microcapsules containing the gas generating agent are arranged between the positive electrode active material layer and the separator of the electrolyte layer or between the negative electrode active material layer and the separator of the electrolyte layer so that the gas generating agent has a desired amount. You may let them.

  In the outermost layer on the positive electrode side, an electrode in which only the positive electrode layer is formed on the current collector is disposed. In the outermost layer on the negative electrode side, an electrode in which only the negative electrode layer is formed on the current collector is disposed. In this manner, the outermost layer current collector for positive electrode and the outermost layer current collector for negative electrode are arranged on both outermost layers of the battery unit or battery stack, respectively.

  Next, a seal portion is provided as necessary. As described above, the seal portion may be disposed between the current collectors so as to surround the single battery layer, or the current collector and the electrolyte layer so as to surround the positive electrode active material layer and the negative electrode active material layer, respectively. You may arrange | position between.

  Finally, in order to prevent external impact and environmental degradation, the entire battery stack is sealed with a battery exterior material or battery case to complete a bipolar battery. At the time of sealing, the tab electrically connected to the outermost layer current collector is taken out of the exterior for the purpose of taking out current outside the battery. Specifically, the positive electrode tab electrically connected to the positive electrode outermost layer current collector and the negative electrode tab electrically connected to the negative electrode outermost layer current collector are taken out of the exterior. The material which comprises a tab (a positive electrode tab and a negative electrode tab) in particular is not restrict | limited, The well-known material conventionally used as a tab of a battery for bipolar | dipolar can be used. Examples of the constituent material of the tab include aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof. Note that the same material may be used for the positive electrode tab and the negative electrode tab, or different materials may be used. Further, as shown in FIG. 3, the outermost layer current collector (371, 372) may be extended to form a tab (371, 372), or a separately prepared tab may be connected to the outermost layer current collector. Good.

  In the bipolar battery, the battery element is preferably housed in an exterior 360 such as a laminate sheet in order to prevent external impact and environmental degradation during use. The exterior is not particularly limited, and a conventionally known exterior can be used. A polymer-metal composite laminate sheet or the like excellent in thermal conductivity can be preferably used in that heat can be efficiently transferred from a heat source of an automobile and the inside of the battery can be rapidly heated to the battery operating temperature.

  The present invention is not limited to the above embodiments, and various modifications, omissions, and additions can be made by those skilled in the art. For example, the bipolar non-aqueous electrolyte secondary battery has been described above as an example. However, the technical scope of the battery of the present invention is not limited to the bipolar battery. For example, FIG. A non-bipolar non-aqueous electrolyte secondary battery as shown may be used.

  Further, the nonaqueous electrolyte secondary battery can be classified into a winding type and a laminated type as shown in FIGS. 5 and 6 depending on the shape of the battery element. However, the present invention is not limited only to the shape and configuration shown in FIGS. The wound type illustrated in FIG. 5 includes a long strip-shaped current collector 510, a positive electrode active material layer, an electrolyte layer, and a current collector 542 in which a positive electrode active material layer is formed on both surfaces of the negative electrode active material layer, A current collector 543 having a negative electrode active material layer formed on both sides is wound around. In FIG. 5, the code | symbol 560 shows an exterior. The stacked type illustrated in FIG. 6 has a shape in which a strip-shaped current collector 640 and a single battery layer 60 including a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer are stacked. In FIG. 6, reference numeral 642 indicates a lead, reference numeral 644 indicates a tab, and reference numeral 660 indicates an exterior. It is preferable that the nonaqueous electrolyte secondary battery is of a stacked type because a gap is easily formed between the layers by the gas.

  A second aspect of the present invention is a vehicle including the nonaqueous electrolyte secondary battery described above.

  Since the non-aqueous electrolyte secondary battery of the present invention has an increased internal resistance when an abnormality occurs, it can suppress damage to external equipment and the occurrence of a vehicle fire, and is excellent in safety.

  EXAMPLES Next, although an Example is given and this invention is demonstrated concretely, these Examples do not restrict | limit this invention at all.

(Comparative Example 1)
[Negative electrode active material layer, current collector for negative electrode]
Hard carbon (diameter 9 μm) was prepared as a negative electrode active material, PVdF as a binder, a copper foil with a thickness of 20 μm as a current collector for a negative electrode, and a nickel foil with a thickness of 100 μm as a tab.

  N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, is mixed with hard carbon and PVdF at a mass ratio of 90:10 so that the slurry viscosity becomes 3 Pa · s. This was added to prepare a negative electrode active material slurry.

  Next, the negative electrode active material slurry was applied to one side of the copper foil so as to have a thickness of 30 μm, and pressed to form a negative electrode active material layer having a thickness of 20 μm on one side of the copper foil. Next, the electrode application part was punched into a “b” shape with a mold so that the electrode application part was a 70 × 70 mm square. The lead portion not coated with the electrode protruding from the electrode coating portion was 15 × 15 mm. A tab made of nickel was attached to the lead.

[Positive electrode active material layer, current collector for positive electrode]
Lithium manganate (LiMn ₂ O ₄ ) as the positive electrode active material, acetylene black as the conductive additive, PVdF as the binder, 20 μm thick aluminum foil as the positive electrode current collector, and 100 μm thick aluminum foil as the tab, Each prepared.

  N-methyl-2-pyrrolidone (NMP) which is a slurry viscosity adjusting solvent is mixed with lithium manganate, acetylene black and PVdF mixed at a mass ratio of 85: 10: 5, and the slurry viscosity is 3 Pa. -It added so that it might become s, and the positive electrode active material slurry was prepared.

  Next, a positive electrode active material slurry was applied to one side of the aluminum foil so as to have a thickness of 30 μm, and pressed to form a positive electrode active material layer having a thickness of 20 μm on one side of the aluminum foil. Next, the electrode application part was punched out in a “d” shape with a mold so that it became a 68 × 68 mm square. The tab portion of the uncoated electrode protruding from the electrode coated portion was 15 × 15 mm. Leads made of aluminum were attached to the tabs.

[Electrolyte layer]
A mixture of PC and EC at a mass ratio of 1: 1 as a non-aqueous solvent and LiPF ₆ as a supporting salt were prepared. An electrolyte solution was prepared by adding LiPF ₆ to 1M with respect to a mixed solution of PC and EC. A polyamide microporous membrane having a porosity of 50% and a thickness of 30 μm was prepared as a separator. The polyamide microporous membrane was punched into a 75 mm × 75 mm square.

[Nonaqueous electrolyte secondary battery]
After arranging the prepared battery elements in the order of current collector for negative electrode with tab-lead, negative electrode active material layer, separator, positive electrode active material layer, current collector for positive electrode with tab-lead, and putting it in an aluminum laminate exterior Ten non-aqueous electrolyte secondary batteries of Comparative Example 1 were prepared by injecting an electrolyte solution and vacuum sealing.

By using a mercury porosimeter method, of the non-aqueous electrolyte secondary battery of Comparative Example 1 were determined with vacancies, the positive electrode active material layer was 0.043 cm ^3, the negative electrode active material layer be 0.045 cm ³ The separator was 0.083 cm ³ , and the entire cell layer was 0.171 cm ³ .

[Charge / discharge test, heating test]
The above non-aqueous electrolyte secondary battery was charged / discharged 10 times between 2.5 and 4.2 V at 30 mA each. The temperature at the time of use of the nonaqueous electrolyte secondary battery of Comparative Example 1 was 25 ° C., and storage at 60 ° C. was performed for 12 hours before the test.

  Next, the obtained secondary batteries were each placed on an iron plate at 200 ° C. and heated for 30 seconds, and then 1 kHz AC impedance was measured to obtain an average value thereof.

  Next, after observing the external appearance of the nonaqueous electrolyte secondary battery, the exterior was peeled off and the inside of the battery was observed.

(Comparative Example 2)
[Negative electrode active material layer, current collector for negative electrode]
A negative electrode active material, a binder, and a negative electrode current collector described in Comparative Example 1 were prepared, and a negative electrode active material layer was formed in the same manner as Comparative Example 1.

[Positive electrode active material layer, current collector for positive electrode]
A positive electrode active material, a conductive additive, a binder, and a positive electrode current collector described in Comparative Example 1 were prepared, and a positive electrode active material layer was formed in the same manner as Comparative Example 1.

[Electrolyte layer]
The electrolyte solution and the separator described in Comparative Example 1 were prepared. Tape-shaped polyimide (width 10 mm) was prepared as a seal part.

  The electrolytic solution was dropped onto the separator to laminate the positive electrode and the negative electrode, tape-shaped polyimide was folded and attached to the positive electrode current collector surface and the negative electrode current collector surface, the battery was adhered, and the gap between the electrodes was sealed.

[Nonaqueous electrolyte secondary battery]
Four battery elements were prepared so that the nonaqueous electrolyte secondary battery was a non-bipolar type, and these were stacked so that the positive electrodes and the negative electrodes faced each other. The tabs of the battery element were joined to the lead made of aluminum and the lead made of nickel, with the positive electrodes and negative electrodes being combined. The lead was taken out of the aluminum laminate so that it could be taken out and vacuum sealed. In this manner, ten nonaqueous electrolyte secondary batteries were produced.

  Using the obtained nonaqueous electrolyte secondary battery, a charge / discharge test and a heating test were conducted in the same manner as in Comparative Example 1.

(Comparative Example 3)
In the same manner as in Comparative Example 1, a negative electrode current collector having a negative electrode active material layer formed on one side and a positive electrode current collector having a positive electrode active material layer formed on one side were produced.

A mixture of PC and EC at a mass ratio of 1: 1 as a non-aqueous solvent and LiPF ₆ as a supporting salt were prepared. What LiPF ₆ was added to a 1M an electrolyte liquid to the liquid mixture of PC and EC, which the PVdF, the electrolyte solution of dimethyl carbonate was added as a solvent: PVdF: dimethyl carbonate mass ratio 45: 5 A polymer solution of 50 was prepared. A polyamide microporous membrane having a porosity of 50% and a thickness of 30 μm was prepared as a separator. The polyamide microporous membrane was punched into a 75 mm × 75 mm square. The polymer solution was applied to a polyamide microporous membrane, and a gel polymer electrolyte impregnated in the separator was prepared by vacuum drying to remove dimethyl carbonate.

  Arrange each battery element produced in the order of current collector for negative electrode with tab-lead, negative electrode active material layer, electrolyte layer, positive electrode active material layer, current collector for positive electrode with tab-lead, put in an aluminum laminate exterior, Vacuum sealed. In this manner, ten nonaqueous electrolyte secondary batteries were produced.

  Using the obtained nonaqueous electrolyte secondary battery, a charge / discharge test and a heating test were conducted in the same manner as in Comparative Example 1.

Example 1
Ten nonaqueous electrolyte secondary batteries were produced in the same manner as in Comparative Example 1 except that the step of attaching the gas generating agent to the separator shown below was added, and a charge / discharge test and a heating test were performed.

  1H-tetrazole as a gas generating agent, water as a dispersion medium of the gas generating agent, and tris (2-ethylhexyl) phosphoric acid as a surfactant for impregnating the separator with an aqueous solution were prepared.

  1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid were mixed at a mass ratio of 5: 94.5: 0.5, and dropped onto the separator. After the dropping, the separator was vacuum dried to evaporate water, and it was confirmed that the mass of the separator was increased by 0.1 mg (that is, 0.0909 mg of 1H-tetrazole was attached).

  Using an airtight container capable of measuring pressure, a gas generation amount of 0.0909 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 2)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and vacuum dried to increase the mass of the separator by 0.2 mg (that is, 0.1818 mg of 1H-tetrazole was attached). Except for the above, ten nonaqueous electrolyte secondary batteries were produced in the same manner as in Example 1, and a charge / discharge test and a heating test were performed.

  Using an airtight container capable of measuring pressure, a gas generation amount of 0.1818 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 3)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuo to increase the mass of the separator by 0.5 mg (that is, 0.4545 mg of 1H-tetrazole was attached). Except for the above, ten nonaqueous electrolyte secondary batteries were produced in the same manner as in Example 1, and a charge / discharge test and a heating test were performed.

  Using a sealed container capable of measuring pressure, a gas generation amount of 0.4545 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

Example 4
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and vacuum dried to increase the separator mass by 1 mg (that is, 0.9091 mg of 1H-tetrazole was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using an airtight container capable of measuring pressure, a gas generation amount of 0.9091 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 5)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuo, increasing the separator mass by 2 mg (that is, 1182 mg of 1H-tetrazole was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using a sealed container capable of measuring pressure, a gas generation amount of 1.8182 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 6)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuum, and the mass of the separator was increased by 5 mg (that is, 4.5454 mg of 1H-tetrazole was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using a sealed container capable of measuring pressure, a gas generation amount of 4.5454 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 7)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuo, increasing the mass of the separator by 10 mg (that is, 9.090 mg of 1H-tetrazole was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using an airtight container capable of measuring pressure, a gas generation amount of 9.0909 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 8)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuo to increase the mass of the separator by 20 mg (that is, 18.1818 mg of 1H-tetrazole was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using a sealed container capable of measuring pressure, the gas generation amount of 18.1818 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

Example 9
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuo, increasing the mass of the separator by 50 mg (that is, 45.4545 mg of 1H-tetrazole was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using a sealed container capable of measuring pressure, the amount of gas generated of 45.4545 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 10)
A mixture of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and vacuum dried to increase the separator mass by 100 mg (that is, 1H-tetrazole was attached 90.9091 mg). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using an airtight container capable of measuring pressure, a gas generation amount of 90.9091 mg of 1H-tetrazole at 200 ° C. normal pressure was calculated.

(Example 11)
A mixture of 5-aminotetrazole, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and dried in vacuo to increase the mass of the separator by 10 mg (that is, 9.0909 mg of 5-aminotetrazole was attached). Except for the above, ten nonaqueous electrolyte secondary batteries were produced in the same manner as in Example 1, and a charge / discharge test and a heating test were performed.

  Using an airtight container capable of measuring pressure, the amount of gas generated of 9.0909 mg of 5-aminotetrazole at 200 ° C. normal pressure was calculated.

(Example 12)
A mixture of sodium azide, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and vacuum dried to increase the mass of the separator by 10 mg (that is, 9.0909 mg of sodium azide was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using an airtight container capable of measuring pressure, the amount of gas generated of 9.0909 mg of sodium azide at 200 ° C. and normal pressure was calculated.

(Example 13)
A mixture of sodium hydrogen carbonate, water, and tris (2-ethylhexyl) phosphoric acid was added dropwise and vacuum dried to increase the mass of the separator by 50 mg (that is, 45.4545 mg of sodium hydrogen carbonate was attached). In the same manner as in Example 1, ten nonaqueous electrolyte secondary batteries were produced, and a charge / discharge test and a heating test were performed.

  Using a sealed container capable of measuring pressure, the amount of gas generated of 45.4545 mg of sodium hydrogen carbonate at 200 ° C. and normal pressure was calculated.

(Example 14)
Before adding the electrolyte solution to the separator, 10 non-aqueous electrolyte secondary batteries were prepared in the same manner as in Comparative Example 2 except that the step of attaching the gas generating agent to the separator as shown below was added. A charge / discharge test and a heating test were performed.

  1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid were mixed at a mass ratio of 5: 94.5: 0.5, and dropped onto the separator. After the dropping, the separator was vacuum dried to evaporate water, and it was confirmed that the mass of the separator was increased by 10 mg (that is, 9.0909 mg of 1H-tetrazole was attached).

(Example 15)
[Negative electrode active material layer, positive electrode active material layer, various current collectors]
The negative electrode active material, the binder, the negative electrode current collector, the positive electrode active material, the conductive additive, the binder, and the positive electrode current collector described in Comparative Example 1 above were prepared.

  On the copper layer side of the bipolar current collector, the same negative electrode active material and binder mixture as in Comparative Example 1 was applied so as to have a thickness of 30 μm, and on the aluminum layer side of the bipolar current collector, A mixture of the same positive electrode active material as in Comparative Example 1, a conductive additive, and a binder was applied so as to have a thickness of 30 μm. Next, pressing was performed to form a negative electrode active material layer having a thickness of 20 μm on the copper layer side and a positive electrode active material layer having a thickness of 20 μm on the aluminum layer side.

  Leads made of nickel were attached to the various current collectors described above.

[Electrolyte layer]
The electrolyte solution and the separator described in Comparative Example 1 were prepared. Tape-shaped polyimide was prepared as a seal part.

  1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid were mixed at a mass ratio of 5: 94.5: 0.5, and dropped onto the separator. After the dropping, the separator was vacuum dried to evaporate water, and it was confirmed that the mass of the separator was increased by 10 mg (that is, 9.0909 mg of 1H-tetrazole was attached).

  Next, an electrolytic solution was dropped onto the separator, and then the contact surface with the positive electrode active material layer and the negative electrode active material layer was left, and the separator was surrounded by a polyimide tape.

[Nonaqueous electrolyte secondary battery]
In order to make the non-aqueous electrolyte secondary battery a bipolar type, each of the produced battery elements was divided into a negative electrode current collector having a negative electrode active material layer formed on one side, an electrolyte layer, a positive electrode active material layer, and a negative electrode active material layer. Three formed current collectors for both electrodes, an electrolyte layer, and a current collector for positive electrode having a positive electrode active material layer formed on one side were arranged in this order, and placed in an aluminum laminate exterior. In this way, ten nonaqueous electrolyte secondary batteries were produced.

  Using the obtained nonaqueous electrolyte secondary battery, a charge / discharge test and a heating test were conducted in the same manner as in Comparative Example 1.

(Example 16)
Before the electrolyte solution was dropped onto the separator, 10 nonaqueous electrolyte secondary batteries were prepared in the same manner as in Comparative Example 3 except that the step of attaching the gas generating agent to the separator as shown below was added. A charge / discharge test and a heating test were performed.

  1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid were mixed at a mass ratio of 5: 94.5: 0.5, and dropped onto the separator. After the dropping, the separator was vacuum dried to evaporate water, and it was confirmed that the mass of the separator was increased by 10 mg (that is, 9.0909 mg of 1H-tetrazole was attached).

(Example 17)
10 nonaqueous electrolyte secondary batteries were prepared in the same manner as in Comparative Example 1 except that the gas generating agent was attached to the positive electrode active material layer as shown below, and a charge / discharge test and heating were performed. A test was conducted.

  1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid were mixed at a mass ratio of 5: 94.5: 0.5 and added dropwise to the positive electrode active material layer. After the dropping, the positive electrode active material layer was vacuum dried to evaporate water, and it was confirmed that the mass of the positive electrode active material layer was increased by 0.1 mg (that is, 0.0909 mg of 1H-tetrazole was attached).

(Example 18)
As a separator, a polypropylene microporous membrane having a porosity of 30% and a thickness of 30 μm and supporting alumina particles with an average particle diameter of 100 nm on the polypropylene microporous membrane by 5 mass% was used. Further, a mixed solution of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was dropped and vacuum dried to increase the mass of the separator by 10 mg (that is, 9.0909 mg of 1H-tetrazole was attached). Except for the above, ten nonaqueous electrolyte secondary batteries were produced in the same manner as in Example 1, and a charge / discharge test and a heating test were performed.

(Example 19)
A polypropylene microporous membrane having a porosity of 30% and a thickness of 30 μm was used as a separator. Further, a mixed solution of 1H-tetrazole, water, and tris (2-ethylhexyl) phosphoric acid was dropped and vacuum dried to increase the mass of the separator by 10 mg (that is, 9.0909 mg of 1H-tetrazole was attached). Except for the above, ten nonaqueous electrolyte secondary batteries were produced in the same manner as in Example 1, and a charge / discharge test and a heating test were performed.

(Example 20)
10 non-aqueous electrolytes in the same manner as in Comparative Example 1 except that a step of arranging a capsule containing dimethyl carbonate as a gas generating agent between the positive electrode active material layer and the separator was added as shown below. A secondary battery was prepared, and a charge / discharge test and a heating test were performed.

Into a polymerization reaction vessel, 89.7 parts by mass of water, 10 parts by mass of colloidal silica (manufactured by ADEKA) and 0.3 part by mass of polyvinylpyrrolidone (manufactured by BASF) are added as a dispersion stabilizer to prepare a dispersion medium. did. Next, 30 parts by mass of acrylonitrile, 40 parts by mass of methacrylonitrile, 30 parts by mass of methacrylic acid, 0.4 parts by mass of dipentaerystol hexaacrylate, 25 parts by mass of dimethyl carbonate, and 1.4 parts by mass of benzoyl peroxide Added to the dispersion medium. Furthermore, 0.5 part by mass of NaOH and ₂ parts by mass of ZnCl ₂ were added to the dispersion medium to prepare a dispersion.

  The resulting dispersion was stirred and mixed with a homogenizer, charged into a pressure polymerizer (capacity 20 L) purged with nitrogen, pressurized at 0.2 MPa, and reacted at 60 ° C. for 20 hours to prepare a reaction product. . Filtration and washing with water of the obtained reaction product were repeated and then dried to obtain dimethyl carbonate contained in a capsule.

  The obtained capsule was heated at 300 ° C., and it was found from the mass difference before and after heating that 9% by mass of dimethyl carbonate was contained in the capsule. Therefore, in order to arrange 20 mg of dimethyl carbonate, 222 mg of capsule was arranged between the positive electrode active material layer and the separator.

(Example 21)
10 nonaqueous electrolyte secondary batteries were produced in the same manner as in Comparative Example 1 except that 9 mg of 1H-tetrazole sandwiched between two separators was used instead of the separator, and a charge / discharge test was performed. And a heating test was performed.

(Comparative Example 4)
A mixed solution in which sodium nitrate, water, and tris (2-ethylhexyl) phosphoric acid were mixed at a mass ratio of 5: 94.5: 0.5 was dropped and vacuum dried to increase the mass of the separator by 1 mg (that is, nitric acid Except that 0.9091 mg of sodium was adhered), 10 non-aqueous electrolyte secondary batteries were produced in the same manner as in Example 1, and a charge / discharge test and a heating test were performed. The gas generation temperature of sodium nitrate is 380 ° C.

  From the results shown in Table 2, it can be seen that in Examples 1 to 21 containing a gas generant and Comparative Examples 1 to 4 not containing a gas generant, Examples 1 to 21 can increase the resistance during overheating. .

  Comparing Example 14 and Example 15, the amount of the bipolar battery in which the single battery layers are arranged in series is the same as that of the non-bipolar battery in which the single battery layers are arranged in parallel. It can be seen that even a gas generating agent is more effective.

  In addition, from the results of Table 2, when battery heating that can normally occur occurs, even if a substance that generates gas at a temperature that greatly exceeds 300 ° C. is added as in Comparative Example 4, the operation of the battery is stopped. You can see that there is no.

10, 20, 30, 60 cell layer,
110, 210, 310, 410 electrolyte layer,
120, 220, 320, 420 Positive electrode active material layer,
130, 230, 330, 430 negative electrode active material layer,
140, 240, 340, 440, 510, 542, 543, 640 current collector,
250, 350, 450 seal part,
341 positive electrode side outermost layer current collector,
342 negative electrode side outermost layer current collector,
360, 460, 560, 660 exterior,
371 positive electrode tab,
372 negative electrode tab,
442, 642 leads,
444, 644 tabs.

Claims (8)

A gas generating agent is included in the surface or inside of at least one layer selected from the group consisting of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer;
The electrolyte layer includes a separator and an electrolytic solution,
A seal portion is disposed around at least the positive electrode active material layer and the negative electrode active material layer,
A nonaqueous electrolyte secondary battery, wherein gas is generated from the gas generating agent when the temperature of the secondary battery reaches 60 ° C or higher and lower than 300 ° C.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the gas generating agent is contained at least on the surface or inside of the electrolyte layer.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the gas generating agent is a compound that generates a gas containing nitrogen or carbon dioxide.   The gas generating agent is at least one selected from the group consisting of azide compounds, azo compounds, sulfonyl hydrazide compounds, hydrazine compounds, nitroso compounds, semicarbazide compounds, tetrazole compounds, bicarbonates, and carbonates. The nonaqueous electrolyte secondary battery according to any one of claims 1 to 3.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the separator includes ceramics.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the seal portion is disposed so as to surround the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the gas generating agent is contained in a capsule.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the nonaqueous electrolyte secondary battery is a stacked type.

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