JP7020167B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

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

The non-aqueous electrolyte secondary battery is also widely used as a power source for mobile devices such as mobile phones and notebook computers and hybrid cars. With the development of these fields, it is required to improve various performances of non-aqueous electrolyte secondary batteries.

One of its performance is safety. Non-aqueous electrolyte secondary batteries generate abnormal heat when they are short-circuited internally. Abnormal heat generation of a non-aqueous electrolyte secondary battery can cause failure of other elements.

Patent Document 1 describes that, in a winding body constituting a power storage unit of a non-aqueous electrolytic solution secondary battery, a region to which an active material is not applied is provided on the outermost circumference or the innermost circumference at least one round. .. When the metal foils come into direct contact with each other when an internal short circuit occurs, the temperature of the non-aqueous electrolyte secondary battery is suppressed from rising abnormally.

Japanese Unexamined Patent Publication No. 8-153542

However, with the recent increase in energy density of the positive electrode active material layer, it may not be possible to sufficiently suppress abnormal heat generation in a state where the charging depth is high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a non-aqueous electrolyte secondary battery having excellent safety even when subjected to external pressure.

When an insulating protective layer is wound around the laminate, even if a metal substance such as a nail is stuck in the non-aqueous electrolyte secondary battery, the surface of the nail is covered with the insulating protective layer. It was found that abnormal heat generation due to an internal short circuit can be suppressed.
That is, in order to solve the above problems, the following means are provided.

(1) The non-aqueous electrolyte secondary battery according to the first aspect includes a positive electrode having a positive electrode current collector and a positive electrode active material layer coated on at least one surface of the positive electrode current collector, and a negative electrode current collector. A laminate having a negative electrode active material layer coated on at least one surface of the negative electrode current collector, a separator, and a laminate having the separator sandwiched between the positive electrode and the negative electrode, and the laminate. It includes an insulating protective layer that wraps around the body, and an exterior body that encloses the laminated body and the protective layer together with an electrolytic solution.

(2) The non-aqueous electrolytic solution secondary battery according to the above aspect has a second laminated body in which a metal layer and a separator are laminated on at least one surface in the stacking direction of the laminated body, and the metal layer is the said. It may be electrically connected to the positive electrode current collector or the negative electrode current collector and have the same potential as the positive electrode current collector or the negative electrode current collector.

(3) The non-aqueous electrolytic solution secondary battery according to the above aspect may include an adhesive portion containing an adhesive substance between the protective layer and the exterior body.

(4) In the non-aqueous electrolytic solution secondary battery according to the above embodiment, the protective layer may be continuously connected and integrated with the separator.

(5) In the non-aqueous electrolytic solution secondary battery according to the above embodiment, the thickness of the protective layer may be thicker than the thickness of the separator.

The non-aqueous electrolyte secondary battery according to the above aspect is excellent in safety even when it receives external pressure.

It is a schematic diagram of the non-aqueous electrolytic solution secondary battery which concerns on this embodiment. FIG. 5 is a schematic cross-sectional view of the non-aqueous electrolytic solution secondary battery according to the present embodiment cut along a plane orthogonal to the direction in which the positive electrode terminal and the negative electrode terminal extend. It is sectional drawing of another example of the non-aqueous electrolytic solution secondary battery which concerns on this embodiment. FIG. 5 is a schematic cross-sectional view of the non-aqueous electrolytic solution secondary battery according to the second embodiment, cut along a plane orthogonal to the direction in which the positive electrode terminal and the negative electrode terminal extend. FIG. 5 is a schematic cross-sectional view of the non-aqueous electrolytic solution secondary battery according to the third embodiment, cut along a plane orthogonal to the direction in which the positive electrode terminal and the negative electrode terminal extend. It is sectional drawing for demonstrating the structure of the non-aqueous electrolytic solution secondary battery in Example 1. FIG. It is sectional drawing for demonstrating the structure of the non-aqueous electrolytic solution secondary battery in Example 4. FIG.

Hereinafter, the present embodiment will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of each component may differ from the actual ones. be. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

"First embodiment"
[Non-water electrolyte secondary battery]
FIG. 1 is a schematic diagram of a non-aqueous electrolytic solution secondary battery according to the present embodiment. The non-aqueous electrolyte secondary battery 100 shown in FIG. 1 includes a power generation element 90 and an exterior body 20. The power generation element 90 is accommodated in the accommodation space K provided in the exterior body 20. A positive electrode terminal 12 and a negative electrode terminal 14 extend from the power generation element 90. FIG. 1 illustrates a state immediately before the power generation element 90 is housed in the exterior body 20 for easy understanding.

(Power generation element)
FIG. 2 is a schematic cross-sectional view of the non-aqueous electrolytic solution secondary battery according to the present embodiment cut along a plane orthogonal to the direction in which the positive electrode terminal 12 and the negative electrode terminal 14 extend. The power generation element 90 includes a laminated body 10 and a protective layer 30.

<Laminated body>
The laminate 10 includes a positive electrode 1, a negative electrode 2, and a separator 3. The separator 3 is arranged between the positive electrode 1 and the negative electrode 2. The positive electrode 1 has a plate-shaped (film-shaped) positive electrode current collector 1A and a positive electrode active material layer 1B. The positive electrode active material layer 1B is formed on at least one surface of the positive electrode current collector 1A. The negative electrode 2 has a plate-shaped (film-shaped) negative electrode current collector 2A and a negative electrode active material layer 2B. The negative electrode active material layer 2B is formed on at least one surface of the negative electrode current collector 2A.

The positive electrode current collector 1A may be a conductive plate material, and for example, a thin metal plate of aluminum, copper, or nickel foil can be used. Further, it is preferable to form an insulating coating film such as aluminum oxide on the surface of the positive electrode current collector 1A. The thickness of the coating film is preferably 50 μm or less. Forming a coating film can further suppress internal short circuits. The coating film slightly reduces the conductivity of the positive electrode current collector 1A, but does not affect the whole.

The positive electrode active material used for the positive electrode active material layer 1B can reversibly proceed with occlusion and release of ions, desorption and insertion (intercalation) of ions, or doping and dedoping of ions and counter anions. Electrode active material can be used. As the ion, for example, lithium ion, sodium ion, magnesium ion and the like can be used, and it is particularly preferable to use lithium ion.

For example, in the case of a lithium ion secondary battery, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), lithium manganese spinel (LiMn ₂ O ₄ ), and general formula: LiNi _x . Coy Mn _z M _a O ₂ (x + _y + z + a = 1, 0 ≦ x <1, 0 ≦ y <1, 0 ≦ z <1, 0 ≦ a <1, M is Al, Mg, Nb, Ti, Cu, Zn , One or more elements selected from Cr), lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMPO ₄ (where M is Co, Ni, Mn, Fe, Mg, (Indicating one or more elements or VO selected from Nb, Ti, Al, Zr), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), LiNi _x Coy Al _z O ₂ (0.9 <x + _y + z <1. Composite metal oxides such as 1), polyacetylene, polyaniline, polypyrrole, polythiophene, polyacene and the like can be used as the positive electrode active material.

The positive electrode active material layer 1B may have a conductive material. Examples of the conductive material include carbon powder such as carbon black, carbon nanotube, carbon material, metal fine powder such as copper, nickel, stainless steel and iron, a mixture of carbon material and metal fine powder, and conductive oxide such as ITO. Be done. When sufficient conductivity can be ensured only by the positive electrode active material, the positive electrode active material layer 1B may not contain the conductive material.

The positive electrode active material layer 1B contains a binder. As the binder, a known binder can be used. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoro Fluororesin such as ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF) and the like can be mentioned.

In addition to the above, examples of the binder include vinylidenefluoride-hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber) and vinylidenefluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFP-TFE-based). Fluororubber), vinylidenefluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluororubber), vinylidenefluo Vinylidene fluoride-based fluorine such as ride-perfluoromethyl vinyl ether-tetrafluoroethylene-based fluorine rubber (VDF-PFMVE-TFE-based fluorine rubber), vinylidene fluoride-chlorotrifluoroethylene-based fluorine rubber (VDF-CTFE-based fluorine rubber) Rubber may be used.

The negative electrode active material used in the negative electrode active material layer 2B may be any compound that can occlude and release ions, and a known negative electrode active material used in a non-aqueous electrolytic solution secondary battery can be used. Examples of the negative electrode active material include alkali or alkaline earth metals such as metallic lithium, graphite capable of storing and releasing ions (natural graphite, artificial graphite), carbon nanotubes, carbon refractory carbon, carbon easily graphitized, and low temperature. Amorphous, mainly composed of carbon materials such as calcined carbon, metals that can be combined with metals such as lithium such as aluminum, silicon, and tin, and oxides such as SiO _x (0 <x <2) and tin dioxide. Examples thereof include particles containing a compound, lithium titanate (Li ₄ Ti ₅ O ₁₂ ) and the like.

As the negative electrode current collector 2A, the conductive material, and the binder, the same ones as those of the positive electrode 1 can be used. As the binder used for the negative electrode, for example, cellulose, styrene / butadiene rubber, ethylene / propylene rubber, polyimide resin, polyamide-imide resin, acrylic resin and the like may be used in addition to those listed for the positive electrode.

Each of the positive electrode 1 and the negative electrode 2 is provided with a positive electrode terminal 12 and a negative electrode terminal 14 for electrical connection with the outside (see FIG. 1). The positive electrode terminal 12 and the negative electrode terminal 14 are formed of a conductive material such as aluminum, nickel, and copper. The positive electrode terminal 12 is connected to the positive electrode 1, and the negative electrode terminal 14 is connected to the negative electrode 2. The connection method may be welding or screwing. It is preferable to protect the positive electrode terminal 12 and the negative electrode terminal 14 with insulating tape in order to prevent a short circuit.

The separator 3 may be formed of an electrically insulating porous structure, for example, a monolayer of a film made of a polyolefin such as polyethylene or polypropylene, a laminate, a stretched film of a mixture of the above resins, or cellulose or polyester. , Polyacrylonitrile, polyamide, polyethylene and a fiber non-woven fabric made of at least one constituent material selected from the group consisting of polypropylene.

The thickness of the separator 3 is preferably 5 μm or more and 30 μm or less, more preferably 8 μm or more and 20 μm or less, and further preferably 10 μm.

Both ends of the laminated body 10 in the stacking direction are preferably a separator 3 or a negative electrode 2. When the laminate 10 generates abnormal heat, the main heat source is the positive electrode 1. By providing the positive electrode 1 inside the laminated body 10, it becomes difficult for a metal body such as a nail that has entered from the outside to reach the positive electrode 1. As a result, it is possible to suppress heat generation of the positive electrode 1 which is a heat source, and it is possible to suppress abnormal heat generation of the entire laminated body 10. Further, when the insulating separator 3 is present on the side close to the outside, a short circuit when receiving an external pressure can be further suppressed.

<Protective layer>
The protective layer 30 winds around the laminated body 10. Since it is difficult to wind the positive electrode terminal 12 and the negative electrode terminal 14 in the extending direction while avoiding these terminals, it is preferable to wind the positive electrode terminal 12 and the negative electrode terminal 14 around the extending direction.

The protective layer 30 has an insulating property. The same material as the separator 3 can be used for the protective layer 30.

The thickness of the protective layer 30 is preferably thicker than that of the separator 3. Specifically, the thickness of the protective layer 30 is preferably 10 μm or more and 40 μm or less, more preferably 10 μm or more and 30 μm or less, and further preferably 20 μm.

The number of turns of the protective layer 30 is one or more, and preferably two or more. On the other hand, from the viewpoint of heat dissipation, it is preferably 4 laps or less, and more preferably 3 laps or less.

The protective layer 30 clings to the metal body when a metal body such as a nail is stuck in the non-aqueous electrolytic solution secondary battery 100. Since the protective layer 30 has an insulating property, it is possible to suppress an internal short circuit even when a metal body such as a nail is pierced.

FIG. 3 is a schematic cross-sectional view of another example of the non-aqueous electrolytic solution secondary battery according to the present embodiment. In the non-aqueous electrolytic solution secondary battery 101 shown in FIG. 3, the protective layer 30 is continuously connected to and integrated with the separator 3 of the laminated body 10. By extending the separator 3 and making it function as the protective layer 30, it is possible to avoid an increase in unnecessary members. In FIG. 3, the separators 3 at both ends of the laminated body 10 in the laminating direction are extended and used as the protective layer 30, but any of the separators 3 in the laminating direction of the laminated body 10 may be extended and used as the protective layer 30. ..

(Exterior body)
The exterior body 20 seals the laminated body 10 and the electrolytic solution inside the exterior body 20. The exterior body 20 is not particularly limited as long as it can prevent the leakage of the electrolytic solution to the outside and the intrusion of water and the like into the non-aqueous electrolytic solution secondary battery 100 from the outside.

For example, as shown in FIG. 2, a metal laminating film in which a metal foil is coated from both sides with a polymer film may be used as the exterior body 20. The exterior body 20 shown in FIG. 2 has a metal foil 21, a resin layer 22 that covers the inner surface of the metal foil 21 on the laminated body 10 side, and a resin layer 23 that covers the outer surface of the metal foil 21 on the opposite side of the laminated body 10. And have.

As the metal foil 21, for example, an aluminum foil can be used. A polymer film such as polypropylene can be used for the resin layer 22 and the resin layer 23. The material constituting the resin layer 22 and the material constituting the resin layer 23 may be different. For example, a polymer having a high melting point, for example, polyethylene terephthalate (PET), polyamide (PA), etc. is used as the outer material, and polyethylene (PE), polypropylene (PP), etc. are used as the material of the inner polymer film. be able to.

In the exterior body 20 shown in FIG. 1, a first surface and a second surface having recesses are folded to form an accommodation space K. The first surface and the second surface are in close contact with each other by sealing the outer circumference. The exterior body 20 is not limited to the one shown in FIG. 1, and may be a bonded body of two films. The recess may be provided in each of the two films, or may be provided in only one of the films.

(Non-water electrolyte)
The non-aqueous electrolytic solution is sealed in the exterior body 20 and impregnated in the laminated body 10.
As the non-aqueous electrolyte solution, an electrolyte solution containing a lithium salt or the like (electrolyte aqueous solution, electrolyte solution using an organic solvent) can be used. However, since the decomposition voltage of the aqueous electrolyte solution is electrochemically low, the withstand voltage during charging is low and limited. Therefore, it is preferable to use an electrolyte solution (non-aqueous electrolyte solution) that uses an organic solvent.

The non-aqueous electrolyte solution has an electrolyte dissolved in a non-aqueous solvent, and may contain a cyclic carbonate and a chain carbonate as the non-aqueous solvent.

As the cyclic carbonate, one capable of solvating an electrolyte can be used. For example, ethylene carbonate, propylene carbonate, butylene carbonate and the like can be used. The cyclic carbonate preferably contains at least propylene carbonate.

The chain carbonate can reduce the viscosity of the cyclic carbonate. For example, diethyl carbonate, dimethyl carbonate and ethylmethyl carbonate can be mentioned. In addition, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane and the like may be mixed and used.

The ratio of cyclic carbonate to chain carbonate in the non-aqueous solvent is preferably 1: 9 to 1: 1 in volume.

As the electrolyte, a metal salt can be used. For example, LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiCF ₃ CF ₂ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ). _2. Lithium salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiN (CF ₃ CF ₂ CO) ₂ , LiBOB can be used. It should be noted that one of these lithium salts may be used alone, or two or more thereof may be used in combination. In particular, from the viewpoint of the degree of ionization, it is preferable to contain LiPF ₆ as the electrolyte.

When dissolving LiPF ₆ in a non-aqueous solvent, it is preferable to adjust the concentration of the electrolyte in the non-aqueous electrolyte solution to 0.5 to 2.0 mol / L. When the concentration of the electrolyte is 0.5 mol / L or more, the lithium ion concentration of the non-aqueous electrolytic solution can be sufficiently secured, and a sufficient capacity can be easily obtained at the time of charging / discharging. Further, by suppressing the concentration of the electrolyte within 2.0 mol / L, it is possible to suppress the increase in the viscosity of the non-aqueous electrolyte solution, sufficiently secure the mobility of lithium ions, and obtain a sufficient capacity during charging and discharging. It will be easier.

Even when LiPF ₆ is mixed with other electrolytes, it is preferable to adjust the lithium ion concentration in the non-aqueous electrolyte solution to 0.5 to 2.0 mol / L, and the lithium ion concentration from LiPF ₆ is 50 mol% thereof. It is more preferable that the above is contained.

[Manufacturing method of non-aqueous electrolyte secondary battery]
First, the positive electrode 1 and the negative electrode 2 are manufactured. The positive electrode 1 and the negative electrode 2 differ only in the material used as the active material, and can be manufactured by the same manufacturing method.

A paint is prepared by mixing a positive electrode active material, a binder and a solvent. If necessary, a conductive material may be further added. As the solvent, for example, water, N-methyl-2-pyrrolidone, N, N-dimethylformamide and the like can be used. The composition ratio of the positive electrode active material, the conductive material, and the binder is preferably 80 wt% to 90 wt%: 0.1 wt% to 10 wt%: 0.1 wt% to 10 wt% in terms of mass ratio. These mass ratios are adjusted to be 100 wt% as a whole.

The method of mixing these components constituting the paint is not particularly limited, and the mixing order is also not particularly limited. The above paint is applied to the positive electrode current collector 1A. The coating method is not particularly limited, and a method usually adopted when manufacturing an electrode can be used. For example, a slit die coat method and a doctor blade method can be mentioned. Similarly, for the negative electrode, the paint is applied on the negative electrode current collector 2A.

Subsequently, the solvent in the paint applied on the positive electrode current collector 1A and the negative electrode current collector 2A is removed. The removal method is not particularly limited. For example, the positive electrode current collector 1A and the negative electrode current collector 2A coated with the paint may be dried in an atmosphere of 80 ° C. to 150 ° C. Then, the positive electrode 1 and the negative electrode 2 are completed.

Next, the separator 3 is arranged between the produced positive electrode 1 and the negative electrode 2 and in a portion that becomes an outer side when rolled up. Then, the positive electrode 1, the negative electrode 2, and the separator 3 are wound around one end side as an axis.

Finally, the laminated body 10 is enclosed in the exterior body 20. The non-aqueous electrolytic solution is injected into the exterior body 20. The non-aqueous electrolytic solution is impregnated into the laminate 10 by reducing the pressure, heating, or the like after injecting the non-aqueous electrolytic solution. The exterior body 20 is sealed by applying heat or the like.

As described above, in the non-aqueous electrolytic solution secondary batteries 100 and 101 according to the present embodiment, the laminated body 10 is wound around the protective layer 30. Therefore, even when a metal body such as a nail is pierced, the insulating protective layer 30 clings to the surface of the metal body, so that short circuits of the non-aqueous electrolytic solution secondary batteries 100 and 101 can be suppressed.

"Second embodiment"
FIG. 4 is a schematic cross-sectional view of the non-aqueous electrolytic solution secondary battery according to the second embodiment, cut along a plane orthogonal to the direction in which the positive electrode terminal and the negative electrode terminal extend. The non-aqueous electrolytic solution secondary battery 102 shown in FIG. 4 is different from the non-aqueous electrolytic solution secondary battery 100 according to the first embodiment in that it has an adhesive portion 40. Other configurations are the same, and the same configurations are designated by the same reference numerals and explanations are omitted.

The adhesive portion 40 is provided between the protective layer 30 and the exterior body 20. For the adhesive portion 40, a double-sided tape or the like having resistance to an electrolytic solution can be used. For example, a product in which an adhesive layer of polyisobutylene rubber is formed on a polypropylene base material, rubber such as butyl rubber, a saturated hydrocarbon resin, or the like can be used.

Even when a metal body such as a nail is pierced, the adhesive substance constituting the adhesive portion 40 first clings to the metal body such as a nail. If the metal body invades the protective layer 30 in that state, the protective layer 30 is more likely to cling to the metal body. As a result, even when a metal body such as a nail is stuck in the non-aqueous electrolytic solution secondary battery 102, the protective layer is attached to the metal body, and it is possible to further suppress the occurrence of an internal short circuit.

As described above, the non-aqueous electrolytic solution secondary battery 102 according to the present embodiment tends to cling to a metal body such as a nail into which the protective layer 30 is pierced by the adhesive portion 40. Therefore, the short circuit of the non-aqueous electrolytic solution secondary battery 102 can be further suppressed.

"Third embodiment"
FIG. 5 is a schematic cross-sectional view of the non-aqueous electrolytic solution secondary battery according to the third embodiment, cut along a plane orthogonal to the direction in which the positive electrode terminal and the negative electrode terminal extend. The non-aqueous electrolytic solution secondary battery 103 shown in FIG. 5 is different from the non-aqueous electrolytic solution secondary battery 100 according to the first embodiment in that it has the second laminated body 50. Other configurations are the same, and the same configurations are designated by the same reference numerals and explanations are omitted.

The second laminated body 50 is provided on at least one surface of the laminated body 10 in the laminating direction. In the second laminated body 50, the separator 3 and the metal layer 4 are alternately laminated.

The metal layer 4 is connected to the positive electrode terminal 12 or the negative electrode terminal 14 (see FIG. 1). The metal layer 4 has the same potential as the positive electrode current collector 1A of the positive electrode 1 or the negative electrode current collector 2A of the negative electrode 2. For the metal layer 4, the same material as the positive electrode current collector 1A and the negative electrode current collector 2A can be used. It is preferable that an insulating film such as an oxide film is formed on the surface of the metal layer 4. When the metal layer 4 has an insulating film, internal short circuits are further suppressed.

The metal layer 4 is made of metal and has excellent heat dissipation. Therefore, by providing the second laminated body 50, heat generation of the laminated body 10 can be suppressed. Further, even when a metal body such as a nail is pierced into the second laminated body 50 and a short circuit occurs, the abnormal heat generation of the laminated body 10 can be suppressed by short-circuiting the metal foils having low resistance.

The number of layers of the metal layer 4 and the separator 3 of the second laminated body 50 may be at least one layer or more. From the viewpoint of heat dissipation, the number of these layers is preferably two or more, and more preferably three or more. On the other hand, in order to avoid increasing the size of the non-aqueous electrolyte secondary battery 103, the number of layers is preferably 3 or less, and more preferably 2 or less.

The thickness of the metal layer 4 is preferably thicker than the thickness of the positive electrode current collector 1A and the negative electrode current collector 2A. Specifically, the thickness of the metal layer 4 is preferably 5 μm or more and 20 μm or less, more preferably 5 μm or more and 15 μm or less, and further preferably 10 μm.

As described above, the non-aqueous electrolytic solution secondary battery 103 according to the present embodiment has the second laminated body 50, so that the heat dissipation can be improved even when the protective layer 30 is provided. As a result, the abnormal heat generation of the non-aqueous electrolyte secondary battery 103 can be further suppressed.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof in each embodiment are examples, and the configurations may be added or omitted within a range not deviating from the gist of the present invention. , Replacements, and other changes are possible.

"Example 1"
(Preparation of positive electrode)
Lithium cobalt oxide (LiCoO ₂ ) was used as the positive electrode active material. 1.90 parts by mass of this positive electrode active material, 5 parts by mass of acetylene black, and 5 parts by mass of polyvinylidene fluoride (PVDF) are dispersed in N-methyl-2-pyrrolidone (NMP) to prepare a slurry. Prepared. The obtained slurry was applied to both sides of an aluminum foil having a thickness of 20 μm. The coating amount is 0.325 g / 1540.25 mm ² . Then, it dried at a temperature of 140 degreeC for 30 minutes.

Next, a roll of the positive electrode was obtained by pressing with a linear pressure of 1000 kgf / cm using a roll press device. Then, a positive electrode 1 having a 10 mm square tab welded portion on one end side was cut out from the roll of the positive electrode. The length of the positive electrode 1 was 77 mm and the width was 70 mm. Then, the positive electrode active material (coating film) was scraped off from the tab welded portion of the positive electrode with a cotton swab impregnated with methyl ethyl ketone (MEK).

(Manufacturing of negative electrode)
A slurry was prepared by dispersing 90 parts by mass of natural graphite powder (negative electrode active material) and 10 parts by mass of PVDF in NMP. The obtained slurry was applied onto a copper foil having a thickness of 15 μm, and one surface of the copper foil was applied with a coating amount of 0.162 g / 1540.25 mm ² . Then, it was dried under reduced pressure at a temperature of 140 ° C. for 30 minutes.

Then, a negative electrode roll was obtained by pressing using a roll press device. A negative electrode 2 having a 10 mm square tab welded portion on one end side was cut out from the negative electrode roll. The negative electrode 2 had a length of 79 mm and a width of 71 mm. Then, the negative electrode active material (coating film) was scraped off from the tab welded portion of the negative electrode with a cotton swab impregnated with MEK to obtain a negative electrode.

(Preparation of separator)
A polyethylene microporous membrane having a film thickness of 20 μm (porosity: 40%, shutdown temperature: 134 ° C.) was prepared. This separator was cut out to a length of 81 mm and a width of 72 mm.

(Preparation of laminated body)
As shown in FIG. 6, the separator 3, the negative electrode 2, the separator 3, and the positive electrode 1 are laminated in this order as one unit C, and three layers are laminated. Further, the separator 3 and the negative electrode 2 are further laminated so that one end side of the laminated body 10 in the stacking direction is the separator 3 and the other end side is the negative electrode 2.

(Preparation of protective layer)
As shown in FIG. 6, the protective layer 30 uses the same material as the separator. The protective layer was wound around the laminate once, and then the ends were fixed with tape.

(Non-water electrolyte)
A non-aqueous electrolyte solution in which LiPF ₆ was dissolved at 1.0 mol / L in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) as an electrolyte was prepared. The volume ratio of EC to DEC in the mixed solvent was EC: DEC = 30: 70.

(Battery production)
The laminated body in which the protective layer was wound was enclosed in an aluminum laminate together with a non-aqueous electrolytic solution to prepare a battery cell of Example 1.

(Measurement of battery surface temperature)
The prepared battery cell of Example 1 was charged with a constant current density of 0.1 C to a charge end voltage of 4.3 V (vs. Li / Li ⁺ ). Further, a constant voltage of 4.3 V (vs. Li / Li ⁺ ) was maintained, and constant voltage charging was performed until the current value decreased to a current density of 0.05 C. The current density was measured with 1C as 158 mA / g. Then, the temperature reached on the surface of the battery was measured.

(Nail piercing test)
A nail with a diameter of 2.5 mm was pierced into a charged battery at a speed of 150 mm / s, and a nail piercing test was conducted. The test was performed on 5 cells and evaluated visually.

The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 2"
Example 2 was the same as that of Example 1 except that the positive electrode active material was LiNi _0.83 Co _0.12 Al _0.05 O ₂ . The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 3"
Example 3 was the same as that of Example 1 except that the positive electrode active material was LiNi _0.6 Co _0.2 Al _0.2 O ₂ . The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 4"
Example 4 was the same as that of Example 1 except that the second laminated body 50 was laminated on both sides of the laminated body 10 in the stacking direction as shown in FIG. 7. In the second laminated body 50, the separator 3, the positive electrode current collector 1A, the separator 3, and the negative electrode current collector 2A were laminated in this order. The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 5"
The same procedure as in Example 1 was carried out except that an adhesive layer was provided between the laminated body and the outer body. The adhesive layer was made larger than the area of the power storage element. Acrylic resin was used for the adhesive layer. The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 6"
Example 6 was the same as in Example 5 except that the positive electrode active material was LiNi _0.83 Co _0.12 Al _0.05 O ₂ . The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 7"
Example 7 was the same as that of Example 5 except that the positive electrode active material was LiNi _0.6 Co _0.2 Al _0.2 O ₂ . The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 8"
Example 8 was the same as that of Example 4 except that an adhesive layer was provided between the laminated body and the exterior body. The adhesive layer was made larger than the area of the power storage element. Acrylic resin was used for the adhesive layer. The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 9"
In the ninth embodiment, a second laminated body 50 in which the separator 3, the positive electrode current collector 1A, the separator 3, and the negative electrode current collector 2A are laminated in this order is further added to both sides of the laminated body 10 in the stacking direction. Was the same as in Example 4. The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Example 10"
In the tenth embodiment, two sets of the second laminated body 50 in which the separator 3, the positive electrode current collector 1A, the separator 3, and the negative electrode current collector 2A are laminated in this order are added to both sides of the laminated body 10 in the stacking direction. Was the same as in Example 4. The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Comparative Example 1"
Comparative Example 1 was the same as that of Example 1 except that the protective layer was not provided. The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Comparative Example 2"
Comparative Example 2 was the same as that of Comparative Example 1 except that the positive electrode active material was LiNi _0.83 Co _0.12 Al _0.05 O ₂ . The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

"Comparative Example 3"
Comparative Example 3 was the same as that of Comparative Example 1 except that the positive electrode active material was LiNi _0.6 Co _0.2 Al _0.2 O ₂ . The main points of the specific configuration of the laminated body are summarized in Table 1, and the surface temperature of the battery and the result of the nail pointing test are summarized in Table 2.

1 Positive electrode 1A Positive electrode current collector 1B Positive electrode active material layer 2 Negative electrode 2A Negative electrode current collector 2B Negative electrode active material layer 3 Separator 4 Metal layer 10 Laminated body 12 Positive electrode terminal 14 Negative electrode terminal 20 Exterior 21 Metal layer 22, 23 Resin layer 30 Protective layer 40 Adhesive part 50 Second laminated body 90 Power generation element 100 Non-aqueous electrolyte secondary battery K Accommodation space

Claims (3)

A positive electrode having a positive electrode current collector and a positive electrode active material layer coated on at least one surface of the positive electrode current collector, and a negative electrode active material layer coated on at least one surface of the negative electrode current collector and the negative electrode current collector. A laminate having a negative electrode and a separator, and laminated with the separator sandwiched between the positive electrode and the negative electrode.
An insulating protective layer that wraps around the laminate and
The laminated body and the outer body that encloses the protective layer together with the electrolytic solution are provided.
The thickness of the protective layer is thicker than the thickness of the separator.
An adhesive portion containing an adhesive substance is provided between the protective layer and the exterior body.
The adhesive portion is a non-aqueous electrolyte secondary battery that adheres the outermost surface of the protective layer to the inner surface of the exterior body . A second laminated body in which a metal layer and a separator are laminated is provided on at least one surface of the laminated body in the laminating direction.
The non-aqueous electrolytic solution according to claim 1, wherein the metal layer is electrically connected to the positive electrode current collector or the negative electrode current collector and has the same potential as the positive electrode current collector or the negative electrode current collector. Secondary battery. The non-aqueous electrolytic solution secondary battery according to claim 1 or 2 , wherein the protective layer is continuously connected and integrated with the separator.

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