JP2003031208A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery with high safety. SOLUTION: This nonaqueous electrolyte secondary battery contains a shut off means isolating between active materials and/or between the active material and a current collector when the inside of the nonaqueous electrolyte secondary battery becomes a prescribed temperature or higher in an active material layer. When the nonaqueous electrolyte secondary battery causes thermal runaway due to unexpected situation, reaction proceeds in succession on the inside of the nonaqueous electrolyte secondary battery to generate heat, and the reaction is further accelerated. When the inside of the nonaqueous electrolyte secondary battery becomes a specified temperature or higher, the connection between the active materials or between the active material and the current collector is isolated and is electrically shut off, and further proceeding of the reaction is prevented to suppress the increase of the temperature inside the nonaqueous electrolyte secondary battery. As the shut off means, thermal expansion powder expanding its volume at a specified temperature or higher is listed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a highly safe non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, high-performance secondary batteries have been actively developed as clean energy sources used in notebook computers, small portable devices, automobiles and the like. The secondary battery used here is required to have a large capacity and a high output while being small and lightweight, that is, a high energy density and a high output density. In addition, it is important to ensure safety because it stores high energy. Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are regarded as promising as secondary batteries capable of achieving high energy density and high output density.

Generally, a lithium secondary battery has a positive electrode capable of releasing lithium ions, a negative electrode capable of absorbing and releasing lithium ions released from the positive electrode, a porous separator interposed between the positive electrode and the negative electrode, and a positive electrode. And an electrolytic solution for moving lithium ions to and from the negative electrode.

[0004] Here, in order to improve the performance of the non-aqueous electrolyte secondary battery such as high energy density and high output, ensuring safety is an important issue. For example, in a lithium secondary battery, chemically active lithium, highly flammable electrolyte,
Since an oxide positive electrode active material having a low thermal stability in a charged state is used, it is necessary to be careful when handling the battery. Particularly when a high-performance lithium battery is put on the market, it is necessary to take sufficient safety measures against the danger due to misuse. For example, there are inconveniences such as battery short circuit, overcharge, and damage to the battery due to misuse such as leaving it at high temperature. One of the causes of inconvenience (thermal runaway) due to misuse is that a chemical reaction between battery materials is accelerated by overheating.

For example, in the overcharged state in which the battery is fully charged, the battery temperature rises due to Joule heat if a current of a certain value or more continues to flow. When this state continues, in the positive electrode, lithium is released from the positive electrode active material, and in the negative electrode, when the negative electrode is carbon, lithium begins to precipitate, or when the negative electrode is lithium metal, lithium dendrite. Is formed. In this way, the positive and negative active materials become unstable.

This unstable positive and negative active material gradually starts an exothermic reaction with the organic electrolyte in the battery when it reaches a certain temperature. Due to this exothermic reaction, the temperature of the battery itself further rises and develops into a rapid reaction at a certain state, resulting in a thermal runaway state accompanied by intense smoke emission.

Various methods have been proposed as measures for improving the safety of this non-aqueous electrolyte secondary battery. For example, a current breaker that disconnects a lead portion through which a current mechanically flows by utilizing the increase in internal pressure of the battery before the occurrence of thermal runaway (Japanese Patent Application Laid-Open No. 200-200200).
0-113874) or a high current flows inside the battery to raise the temperature, the PTC element (Japanese Patent Laid-Open No. 11-273651) and the positive electrode active material whose resistance value increases as the temperature rises (Japanese Laid-Open Patent Publication No.
161389) to increase the resistance, polypropylene or polyethylene having a low melting point is used as a separator, and there is a method of cutting off the overcurrent due to the shutdown effect of the separator due to the rise of the internal temperature of the battery. However, these methods are not sufficiently practical in applications where high reliability such as automobile power is required due to malfunctions due to vibrations, increased battery cost, low reliability, and the like.

In addition, the thermosensitive microcapsules are contained in the battery, the electrolytically polymerizable monomer is released as the battery temperature rises, and the electrolytic solution is polymerized to lower the ionic conductivity of the electrolytic solution, thereby improving the battery characteristics. There is a method (Japanese Patent Application Laid-Open No. 9-45369, Japanese Patent Application Laid-Open No. 10-270084).
However, since these methods take a long time for the polymerization reaction, it is difficult to lose the battery characteristics within a short time from the start of the exothermic reaction between the overcharge electrode and the electrolytic solution to the thermal runaway, Not enough effect.

[0009]

As described above, although many safety measures have been conventionally developed, there is no end to the demand for further improvement in safety. It is also effective to develop and use various kinds of safety measures in order to improve safety.

Therefore, it is an object of the present invention to provide a non-aqueous electrolyte secondary battery whose safety is ensured by means different from the conventional one.

[0011]

Means for Solving the Problems The present inventors have made the following inventions as a result of earnest researches for the purpose of solving the above problems. That is, the non-aqueous electrolyte secondary battery of the present invention comprises a positive electrode having at least one of an active material layer containing a current collector and an active material capable of inserting and extracting lithium ions formed on the current collector. In the non-aqueous electrolyte secondary battery having a negative electrode, the active material layer, when the inside of the non-aqueous electrolyte secondary battery is a predetermined temperature or higher, between the active materials and / or and the active material The present invention is characterized by including a breaking means having a characteristic of electrically isolating the current collector by isolating it from the current collector.

When the non-aqueous electrolyte secondary battery undergoes thermal runaway due to an unforeseen situation, heat is generated inside the non-aqueous electrolyte secondary battery as a result of chain reaction, and the reaction is further promoted. . Therefore, when the inside of the non-aqueous electrolyte secondary battery reaches a predetermined temperature or higher, the active materials are separated from each other and / or the active material and the current collector are isolated from each other and electrically cut off. The reaction is prevented from proceeding and the temperature inside the non-aqueous electrolyte secondary battery is prevented from rising.

As the shut-off means, a thermal expansion powder which causes volume expansion at a predetermined temperature or higher is used in the active material layer (claim 2).
Alternatively, it can be achieved by being present on or in the separator made of a porous film (Claim 5) or in the non-aqueous electrolyte (Claim 6).

When the battery temperature rises, such as when the battery is abnormal, the thermal expansion powder causes volume expansion in the active material layer, so that volume expansion occurs between the active materials in the same pole and between the active material and the current collector. The thermal expansion powder thus entered penetrates and cuts off the conductive path in the electrode, so that its electrical connection can be cut off. In that case, the preferable particle diameter of the thermal expansion powder is 3 times or less the particle diameter of the active material (claim 3). By setting the particle diameter in this range, the conductivity between the active materials can be ensured at a predetermined temperature or lower, and the thermal expansion powder can be uniformly present around the active material. Further, it is more preferable that the particle diameter of the thermal expansion powder is equal to or larger than the particle diameter of the conductive material contained in the active material layer (claim 4). By setting the particle size to be equal to or larger than that of the conductive material, it is possible to more reliably cut off the electrical connection during volume expansion.

The volume of the thermally expanded powder expands on or inside the separator, so that the pores of the separator can be closed and the ionic conduction between the positive electrode and the negative electrode can be blocked. Similarly, the thermal expansion powder expands in volume in the non-aqueous electrolytic solution, so that the ionic conduction between both electrodes can be blocked.

As the thermal expansion powder which causes volume expansion at a predetermined temperature or higher, a powder containing a chemical foaming agent or a physical foaming agent can be exemplified (Claim 7). Specifically, the boiling point is not higher than the predetermined temperature. Examples thereof include microcapsules in which a low boiling point liquid is enclosed (claim 8) and powders (claim 9) formed from a material that undergoes a phase transition with a volume change at a predetermined temperature.

The above-mentioned predetermined temperature is 80 to 180 ° C.
From the viewpoint of ensuring safety (claim 10). In particular, by setting the predetermined temperature to be equal to or lower than the thermal runaway start temperature, the battery does not run into thermal runaway.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The non-aqueous electrolyte secondary battery of the present invention will be described below based on an embodiment applied to a lithium secondary battery. The present invention is not limited to the embodiments below.

The lithium secondary battery of this embodiment has at least one of a positive electrode and a negative electrode having a current collector and an active material layer formed on the current collector and containing an active material capable of inserting and extracting lithium ions. . Further, when the inside of the non-aqueous electrolyte secondary battery has reached a predetermined temperature or higher, the active material and / or the active material and the current collector are isolated from each other and electrically isolated. It also has other elements as required.
The predetermined temperature is preferably between 80 and 180 ° C. By setting the temperature lower than the temperature at which the thermal runaway inside the battery progresses and does not reach in the normal use condition, thermal runaway can be surely prevented and malfunction can be prevented.

As the blocking means, there is a thermal expansion powder which expands in volume at a predetermined temperature or higher. As the thermal expansion powder,
Examples thereof include thermal expansion microcapsules in which a low boiling point liquid or the like is enclosed, and powders made of a substance that expands in volume by a phase transition.

The thermal expansion powder is preferably contained / dispersed in the electrode described later. As a method of containing / dispersing in the electrode, the thermal expansion powder can be dispersed between the active materials by mixing with an active material described later to form an electrode. It may be dispersed in either the positive or negative electrode, or may be contained in both electrodes. By containing thermal expansion powder in the electrode, the electrode expands in volume at a predetermined temperature in the process of thermal runaway such as overcharge, and the conductive path (between active materials, between active material and current collector) in the electrode. ), The active material can be isolated and the battery resistance can be rapidly increased. This increase in battery resistance makes it possible to cut off the overcharge current. In this case, the particle size of the thermal expansion powder is preferably 3 times or less the particle size of the active material described later. Further, it is preferable that the particle size is equal to or larger than the particle diameter of the conductive material described later.

Similar effects are expected when the thermal expansion powder is contained in a separator or an electrolytic solution.
Further, in a battery employing a solid electrolyte, it can be contained therein. Originally, a polyethylene separator or a polypropylene separator has a shutdown function of melting the separator when it reaches a predetermined temperature, blocking the opening of the separator and blocking the permeation of ions. Further, by containing the above-mentioned thermally expanded microcapsules in the separator, it is possible to expand the volume at an arbitrary predetermined temperature and block the holes of the separator to increase the resistance.

Further, the thermal expansion powder is contained in the separator or the like, so that the thickness between the positive and negative electrodes, that is, the distance between the positive and negative electrodes is widened, which also has the effect of increasing the battery resistance. By including the thermal expansion powder in the battery, the current can be cut off even before the temperature at which the shutdown function originally possessed by the separator is reached.

This thermal expansion powder has azo compounds, nitroso compounds, hydrazine derivatives, semicarbazide compounds, tetrazole compounds, isocyanate compounds, bicarbonates / carbonates, nitrites / hydrides, sodium bicarbonate + acids, peroxides inside. Chemical blowing agents such as hydrogen + yeast, zinc powder + acid, butane, pentane, hexane, dichloroethane, dichloromethane, freon, air, carbon dioxide,
It is made of a thermoplastic resin containing a physical foaming agent such as nitrogen gas.

Among them, the thermally expandable microcapsules are preferably those which undergo volume expansion when the internal pressure becomes a sufficient pressure to expand the microcapsules due to vaporization of the low boiling point liquid inside. As a method for controlling the predetermined temperature at which the volume expands, as the low boiling point liquid to be sealed inside, by selecting a liquid whose boiling point is near the predetermined temperature,
It can be controlled easily. Further, in order to facilitate the volume expansion, it is also preferable to form the portion forming the outer shell portion of the microcapsule with a thermoplastic resin or the like having a softening point at a predetermined temperature or lower. For forming the microcapsules, a known method such as a coacervation method can be adopted.

As the thermal expansion microcapsule, for example, Expancel 051D manufactured by Nippon Ferrite Co., Ltd.
U, 007WU, 053WU, 053DU, 054W
U, 091DU, 091-080DU, 091-140
-DU, 092-120DU, 093-120DU, 8
20 WU, 642 WU, 551 WU, 551 DU, 55
1-20 WU, 551-20 DU, 551-80 WU,
551-80DU, 461WU, 461DU, 461-
20 and Microcapsule F- manufactured by Matsumoto Yushi Co., Ltd.
20, F-30, F-40, F-50, F-80S, F
-82, F-85, F-100, etc. These materials are composed of an outer shell of a copolymer and a low hydrocarbon with a low boiling point inside, and when the temperature reaches a predetermined temperature between about 70 ° C and 200 ° C, the outer shell softens. And, due to the vaporization of the contents, its own volume expands up to 40-60 times.

As the substance that expands in volume by the phase transition,
For example, thermal expansion rubber manufactured by Togawa Rubber Co., Ltd. can be exemplified.

Further, as the shut-off means, means for monitoring the battery temperature from the outside and, when the battery temperature becomes a predetermined temperature or more, applying vibration or the like to the battery to collapse the electrodes and the like inside the battery is cited. To be

The lithium secondary battery of this embodiment is not particularly limited in its shape, and may be a coin type, a cylindrical type, a square type, or the like.
It can be used as a battery of various shapes. In this embodiment,
The description will be given based on a cylindrical lithium secondary battery.

In the lithium secondary battery of this embodiment, a positive electrode and a negative electrode are formed into a sheet shape, and both are laminated with a separator interposed between them. It is stored in the case. The positive electrode and the positive electrode terminal portion are electrically connected to each other, and the negative electrode and the negative electrode terminal portion are electrically connected to each other.

The positive electrode has a positive electrode active material capable of releasing lithium ions during charging and occluding lithium ions during discharging. Examples of the positive electrode active material include a lithium-metal composite oxide-containing active material that is at least one kind of a lithium-metal composite oxide having a layered structure or a spinel structure.

As an active material containing a lithium-metal composite oxide
For example, Li_(1-X)NiO₂, Li_(1-X)Mn
O₂, Li_(1-X)Mn₂O_Four, Li_(1-X)CoO₂, Li
_(1-X)FeO ₂Etc., Li, Al, Cr, etc.
For example, a material to which a transition metal is added or replaced. This example
X in represents a number of 0 to 1. In addition, these Richiu
When using a metal-metal composite oxide as the positive electrode active material,
Not only used alone, but also as a mixture of multiple types
You can also Among these, lithium-metal composite acid
As the compound-containing active material, a layered structure or a spinel structure
Lithium manganese-containing composite oxide, lithium nickel
-Containing complex oxide and lithium-cobalt-containing complex oxide
It is preferable that it is one or more of the above. Cost reduction
From the viewpoint, the lithium-metal composite oxide-containing active material is a layer.
-Like structure or spinel structure containing lithium manganese
Of oxides and lithium nickel-containing composite oxides
More preferably, it is one or more.

The positive electrode is formed by mixing the above-mentioned positive electrode active material with a known additive such as a binder and a conductive material and then applying the mixture on a current collector made of metal foil or the like to form a positive electrode mixture layer.

The negative electrode is not particularly limited in material constitution as long as it can use a negative electrode active material which absorbs lithium ions during charging and discharges during discharging, and a known material and constitution can be used. You can For example, it is a carbon material such as lithium metal, graphite or amorphous carbon. Among them, it is particularly preferable to use a carbon material. Since the carbon material can have a relatively large specific surface area and has a high lithium absorption / desorption rate, it has good charging / discharging characteristics at a large current and good output / regeneration density. In particular, in consideration of the balance between the output and the regenerative density, it is preferable to use a carbon material having a relatively large voltage change with charge and discharge. Further, by using such a carbon material as the negative electrode active material, higher charge / discharge efficiency and good cycle characteristics can be obtained.

When the carbon material is used as the negative electrode active material as described above, the negative electrode mixture obtained by mixing the conductive material and the binder as necessary is applied to the current collector. It is preferable to use one.

The non-aqueous electrolytic solution is a solution in which a supporting salt is dissolved in an organic solvent.

The organic solvent is not particularly limited as long as it is an organic solvent usually used in an electrolytic solution of a lithium secondary battery, and examples thereof include carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, Lactones,
An oxolane compound or the like can be used. In particular, propylene carbonate, ethylene carbonate, 1,2-
Dimethoxyethane, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and the like and mixed solvents thereof are suitable.

Among these organic solvents listed as examples, by using at least one non-aqueous solvent selected from the group consisting of carbonates and ethers, the solubility, dielectric constant and viscosity of the supporting salt can be improved. It is preferable because it is excellent and the charge / discharge efficiency of the battery is high.

The type of the supporting salt is not particularly limited, but an inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , a derivative of the inorganic salt, LiSO ₃ CF ₃ , LiC (SO). ₃ CF ₃ ) ₂ , LiN
(SO ₃ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and Li
It is preferably at least one of an organic salt selected from N (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ) and a derivative of the organic salt.

By using these supporting salts, the battery performance can be further improved, and the battery performance can be maintained even higher in a temperature range other than room temperature. The concentration of the supporting salt is not particularly limited, and it is preferable to appropriately select it in consideration of the types of the supporting salt and the organic solvent according to the application.

The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a porous film of polyolefin polymer (polyethylene, polypropylene) may be used. The separator is preferably larger than the positive electrode and the negative electrode in order to ensure the insulation between the positive electrode and the negative electrode.

The case is not particularly limited,
It can be made of a known material and form.

The gasket ensures electrical insulation between the case and both the positive and negative terminal portions and the airtightness inside the case. For example, the electrolyte may be composed of a polymer such as polypropylene that is chemically and electrically stable.

[0044]

EXAMPLES Example 1 (Preparation of Battery) (Preparation of Positive Electrode) LiNiO ₂ as a positive electrode active material was added to 80%.
Parts by mass, 10 parts by mass of acetylene black as a conductive material, 2 parts by mass of sodium carboxymethyl cellulose, 1 part by mass of polytetrafluoroethylene, and thermally expanded microcapsules as thermally expanded powder (manufactured by Nippon Philite Co., Ltd.). DU051) was mixed with 10 parts by mass to obtain a positive electrode material. This positive electrode material was dispersed in water to form a slurry. This slurry was applied on both sides of a positive electrode current collector made of aluminum, dried and then the pressing pressure was adjusted to obtain a positive electrode plate. Then, this positive electrode plate was cut into a predetermined size, and a sheet-shaped positive electrode was produced by scraping off the electrode mixture material in the portion that will be the lead tab weld for current extraction. This sheet-shaped positive electrode has a thermal expansion powder between the positive electrode active materials.

(Production of Negative Electrode) 92.5 parts by mass of carbon material powder as a negative electrode active material and 7.5 parts by mass of PVDF were mixed to prepare a negative electrode material. This negative electrode material was dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry. This slurry was applied to both surfaces of a negative electrode current collector made of copper, dried and press-molded to obtain a negative electrode plate in the same manner as the positive electrode. Then, this negative electrode plate was cut into a predetermined size, and the sheet-shaped negative electrode was produced by scraping off the electrode mixture material in the portion which will be the lead tab weld for current extraction.

(Preparation of Electrolyte Solution) A mixed organic solvent of ethylene carbonate, diethyl carbonate and 3: 7 was added to Li.
PF ₆ was dissolved at a concentration of 1 mol / liter to prepare an electrolytic solution.

(Assembly of Battery) The sheet-shaped positive electrode and the sheet-shaped negative electrode obtained as described above are wound in a state of interposing a film made of microporous polyethylene having a thickness of 25 μm as a separator to form a wound electrode body. Was formed. The obtained wound electrode body was inserted into the case and held in the case. At this time, one end of the current collecting lead was welded to the lead tab welding portion of the sheet-shaped positive electrode and the sheet-shaped negative electrode, and the other ends of the current collecting lead were joined to the positive electrode terminal and the negative electrode terminal of the case, respectively. After that, the electrolytic solution was injected into the case holding the spirally wound electrode body, and then the case was sealed and sealed.

By the above procedure, a cylindrical lithium secondary battery having a diameter of 18 mm and an axial length of 65 mm was manufactured.

(Regarding Thermal Expansion Microcapsule) The thermal expansion microcapsule used in this example is 1
Volume expansion occurs at 06 ° C or higher. The volume expansion is about 60 times in volume ratio when the thermally expanded microcapsules alone are heated.

Example 2 Preparation of Positive Electrode 85 parts by mass of LiNiO ₂ , 10 parts by mass of acetylene black and 5 parts by mass of PVDF were mixed to prepare a positive electrode material. This positive electrode material is N-methyl-
2-pyrrolidone (NMP) was dispersed to make a slurry, and then a sheet-shaped positive electrode was produced by the same operation as in the battery of Example 1.

(Preparation of Negative Electrode) 98 parts by mass of carbon material powder, 1 part by mass of sodium carboxymethyl cellulose, 1 part by mass of SBR, and 10 parts by mass of thermal expansion microcapsules (DU051 manufactured by Nippon Philite Co., Ltd.). Were mixed to obtain a negative electrode material. This negative electrode material was dispersed in water to form a slurry, and then a sheet-shaped negative electrode was produced by the same operation as in Example 1. This sheet-shaped negative electrode has a thermal expansion powder between positive electrode active materials.

(Assembly of Battery) The sheet-like positive electrode and the sheet-like negative electrode obtained above were combined in the same manner as in the battery assembling method of Example 1 to prepare a battery of Example 2.

<Comparative Example> The sheet-shaped negative electrode of Example 1 and the sheet-shaped positive electrode of Example 2 were combined in the same manner as in the battery assembly method of Example 1 to prepare a battery of Comparative Example. That is, the battery of the comparative example has the same configuration as that of the batteries of Examples 1 and 2 except that it does not have the thermal expansion powder.

<Test> (Initial discharge capacity) For each battery, charging current 0.25 m
Constant current / constant voltage charging up to 4.1V at A / cm ²
Then, constant current discharge was performed at a discharge current of 0.33 mA / cm ² to 3.0 V. Next, charging current 1.1 mA / cm ²
After constant current / constant voltage charging up to 4.1V, discharge current 1.1
Four cycles of constant current discharge at mA / cm ^{2 up} to 3.0 V were performed. And charging current 1.1mA / c
Constant current / constant voltage charging was performed up to 4.1 V at m ² . After that, the discharge capacity when constant current discharge was performed up to 3.0 V at a discharge current of 0.33 mA / cm ² was taken as the battery initial capacity. The measurement was performed in an atmosphere of 20 ° C.

(Overcharge test) For the purpose of investigating the stability of the battery under severe conditions, the charging current was 1.5 m up to 4.1V.
Each battery in a fully charged state, which was charged at a constant current and a constant voltage at A / cm ² , was then continuously charged at 5 A until further charged to 250%, and the battery temperature and the battery behavior at that time were observed.

<Results> Table 1 shows the battery capacity ratios and the results of overcharge tests of the batteries of Examples 1, 2 and Comparative Example. The discharge capacity ratio was set to 100 for the battery of the comparative example.

[0057]

[Table 1]

As is clear from Table 1, the inclusion of the thermally expanded microcapsules in either electrode
It has become possible to suppress thermal runaway during overcharge. The decrease in battery capacity of the batteries of the respective examples containing a sufficiently effective amount of the thermal expansion microcapsules was very small as compared with the batteries containing no thermal expansion microcapsules.

Further, the sheet-like positive electrodes of Example 1 and Example 2 (comparative example) were measured for specific resistance before and after heat treatment (before and after volume expansion of thermally expanded microcapsules). The results are shown in Table 2.

[0060]

[Table 2]

As is clear from Table 2, it was found that the sheet-shaped positive electrode of Example 1 having the thermal expansion microcapsules had a significantly increased specific resistance after heat treatment. This increase in resistivity is significantly lower than the temperature at which thermal runaway progresses13
It should be noted that the process proceeds even under conditions of 0 ° C. and 1 minute or less. In addition, since the thermal expansion microcapsule expands rapidly at a predetermined temperature and does not change below the predetermined temperature, malfunction of the breaking means below the predetermined temperature or temperature rise due to operation of the breaking means results in a battery. It can be expected that the deterioration of the performance can be prevented, and at the same time, the battery reaction can be promptly cut off at a predetermined temperature or higher.

[0062]

As described above, the non-aqueous electrolyte secondary battery of the present invention can provide a highly safe non-aqueous electrolyte secondary battery.

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Claims (10)

[Claims] 1. A non-aqueous electrolyte secondary having a positive electrode and a negative electrode having at least one of an active material layer containing a current collector and an active material capable of inserting and extracting lithium ions formed on the current collector. In the battery, the active material layer isolates between the active materials and / or between the active material and the current collector when the temperature inside the non-aqueous electrolyte secondary battery rises to a predetermined temperature or higher. A non-aqueous electrolyte secondary battery comprising a shut-off means having a characteristic of electrically shutting off. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the blocking means is a thermal expansion powder which is dispersed in the active material layer and causes volume expansion at a predetermined temperature or higher. 3. The non-aqueous electrolyte secondary battery according to claim 2, wherein the particle diameter of the thermal expansion powder is 3 times or less the particle diameter of the active material. 4. The active material layer includes a conductive material that imparts conductivity between the active materials and between the active material and the current collector, and a particle diameter of the thermal expansion powder is equal to that of the conductive material. The non-aqueous electrolyte secondary battery according to claim 2, which has a particle size or more. 5. The separator further comprises a separator made of a porous material sandwiched between the positive electrode and the negative electrode, wherein the blocking means causes a volume expansion at a temperature equal to or higher than a predetermined temperature to close a hole of the separator. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein expanded powder is provided on or in the separator. 6. The non-aqueous electrolyte solution is further provided, and the blocking means has a thermal expansion powder which causes volume expansion at a predetermined temperature or higher in the non-aqueous electrolyte solution. Non-aqueous electrolyte secondary battery. 7. The non-aqueous electrolyte secondary battery according to claim 2, wherein the thermal expansion powder is a powder containing a chemical foaming agent or a physical foaming agent inside. 8. The non-aqueous electrolyte secondary battery according to claim 2, wherein the thermal expansion powder is a microcapsule in which a low boiling point liquid is enclosed. 9. The non-aqueous electrolyte secondary pond according to claim 2, wherein the thermal expansion powder is formed of a material in which the predetermined temperature is a phase transition temperature accompanied by a volume change. 10. The non-aqueous electrolyte secondary battery according to claim 1, wherein the predetermined temperature is between 80 and 180 ° C.