KR20130103404A - Non-aqueous electrolytic secondary battery and manufacturing method for the same - Google Patents

Abstract

PURPOSE: A manufacturing method of a secondary battery (10) is provided to prevent a short circuit and to provide a secondary battery with excellent battery output. CONSTITUTION: A manufacturing method of a non-aqueous secondary battery (10) having a laminate in which a negative electrode active material layer (12), a positive electrode active material layer (15), a separator (13), and a heat resistant layer are laminated includes a step of manufacturing the heat resistant layer by hot-pressing the laminate in which a heat resistant precursor layer is insert-supported by the active material layer and the separator. The heat resistant precursor layer includes a first particle and a second particle whereby the melting point for the second particle is higher than that of the first particle. The heat compression temperature of the heat resistant precursor layer is higher than the melting point of the first particle and lower than that of the second particle and that of the separator.

Description

TECHNICAL FIELD [0001] The present invention relates to a non-aqueous electrolyte secondary battery,

The present invention relates to a nonaqueous electrolyte secondary battery and a manufacturing method thereof.

Recently, development of electric vehicles (EVs), hybrid electric vehicles (HEVs) and fuel cell vehicles (FCVs) are under development as a result of the heightened environmental protection movement. A secondary battery capable of repeatedly charging and discharging is suitable as the motor driving power source, and a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery which can expect high capacity and high output is attracting attention.

The nonaqueous electrolyte secondary battery has a positive electrode active material layer including a positive electrode active material (for example, LiCoO2, LiMnO2, LiNiO2, etc.) formed on the surface of the current collector. The non-aqueous electrolyte secondary battery includes a negative electrode active material (for example, a carbonaceous material such as metal lithium, coke, natural and artificial graphite, a metal such as Sn and Si, and an oxide material thereof) And a negative electrode active material layer. The nonaqueous electrolyte secondary battery has an electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer and including an electrolyte (electrolyte) separating the positive electrode active material layer and the negative electrode active material layer.

In such a nonaqueous electrolyte secondary battery, a secondary battery is known in which a positive electrode active material layer, a negative electrode active material layer, and a separator interposed between the active material layers are bonded together by an adhesive resin layer (see, for example, Patent Document 1). By having such an adhesive resin layer, the adhesion between the positive electrode active material layer, the negative electrode active material layer and the separator can be increased, and the battery reaction can be promoted.

Japanese Patent Application Laid-Open No. 10-172537

However, in a secondary battery having an adhesive resin layer, when the internal temperature of the battery exceeds the separator melting point due to some cause, the separator is thermally shrunk, shorting between the positive electrode active material layer and the negative electrode active material layer, There is a concern. Therefore, a method of forming a separator having a high melting point in addition to the adhesive resin layer so as to isolate the positive electrode active material layer and / or the negative electrode active material layer and the adjacent separator from each other is considered to prevent a short circuit. However, when the isolation layer is formed, the thickness of the isolation layer is increased as compared with the prior art, and battery performance such as battery output is deteriorated.

Therefore, it is an object of the present invention to provide a non-aqueous electrolyte secondary battery which can prevent short-circuiting and is excellent in battery output.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined in order to solve the said subject. As a result, the above problem can be solved by forming the heat resistant layer by thermally compressing the laminated body in which the heat-resistant precursor layer containing two particles having different melting points are sandwiched by the active material layer and the separator at a predetermined temperature And reached the completion of the present invention. That is, the present invention provides a nonaqueous electrolyte secondary battery comprising a negative electrode active material layer, a positive electrode active material layer, a separator, and a laminate electrode body in which the negative electrode active material layer or the heat resistant layer disposed between the positive electrode active material layer and the separator are laminated And a method for producing the same. The production method is characterized in that a laminate in which a heat-resistant precursor layer comprising a first particle and a second particle having a melting point higher than that of the first particle are sandwiched by an active material layer and a separator is set to be higher than the melting point of the first particle, And thermally compressing the second particles at a temperature lower than the melting point of the second particles and the melting point of the separator to thereby fabricate the heat resistant layer.

According to the present invention, a laminate including a heat-resistant precursor layer containing two particles having different melting points between an active material layer and a separator is thermally compressed at a predetermined temperature so that one of the particles (first particle) of the heat- And is melted to form a heat resistant layer. The molten particles become a bonding point, and the active material layer and the separator are bonded via the heat resistant layer. Further, the other particles (second particles) of the heat-resistant precursor layer exist as particles in the heat-resistant layer even after the heat compression, so that the particles in the heat-resistant layer have an effect of insulating the separator from the active material layer. As a result, a non-aqueous electrolyte secondary battery having an excellent battery output having a heat resistant layer having both an adhesive layer for promoting the cell reaction and an isolating layer for preventing a short circuit is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view schematically showing the outline of a laminated battery which is one embodiment of the battery of the present invention.
2 is a schematic cross-sectional view schematically showing a heat-resistant layer in one embodiment of the battery of the present invention.
3 is a schematic cross-sectional view schematically showing a heat-resistant layer in one embodiment of the battery of the present invention.

The present invention relates to a nonaqueous electrolyte secondary battery comprising a negative electrode active material layer, a positive electrode active material layer, a separator, and a laminated electrode body in which the negative electrode active material layer or the heat resistant layer disposed between the positive electrode active material layer and the separator are laminated A method for producing a laminated body comprising a laminated body in which a heat-resistant precursor layer comprising a first particle and a second particle having a melting point higher than that of the first particle is sandwiched by the active material layer and the separator, And thermally compressing the second particles at a temperature lower than the melting point of the second particles and the melting point of the separator to produce the heat resistant layer.

In the present embodiment, the laminate including the heat-resistant precursor layer containing two particles having different melting points between the active material layer and the separator is thermally compressed at a predetermined temperature. As a result, one of the particles of the heat-resistant precursor layer is melted, and the molten particles serve as a junction at which the active material layer and the separator are bonded to each other via the heat-resistant layer. In addition, since the other particle exists as a particle | grain in a heat resistant layer after thermal compression, it becomes an isolation point which isolate | separates an active material layer and a separator. Therefore, the heat-resistant layer of the present embodiment combines the effect of the adhesive layer for promoting the cell reaction and the insulating layer for preventing the short circuit. Further, since the heat resistant layer has the effect of the adhesive layer and the quenching layer, the non-aqueous electrolyte secondary battery of the present embodiment does not need to use two layers of the adhesive layer and the quenching layer together, The thickness can be omitted, and the thickness of the entire battery can be omitted. Further, since the first particles are dispersed in the heat-resistant precursor layer, the first particles are melted by thermal compression, and the melted regions are dotted in the heat-resistant layer. That is, the junction where the first particles are melted and the isolation point where the second particles exist are dotted and mixed. As a result, the bonding point of the active material layer or the separator and the heat resistant layer is also dotted without being present on one side of the bonding surface. The junction resistance of the active material layer and the high-resistance heat-resistant layer is limited, so ion conduction resistance can be reduced as compared with a form in which one surface of the active material layer is covered with the heat-resistant layer. In addition, the lithium ion secondary battery of the present embodiment does not have the same layer-like insulating layer as the adhesive layer, and the output is improved.

Hereinafter, embodiments of the present invention will be described. In the following, a lithium ion secondary battery is described as an example, but the present invention is also applicable to a secondary battery other than a lithium ion secondary battery.

<Overall Structure of Non-aqueous Electrolyte Secondary Battery>

First, the overall structure of a lithium ion secondary battery obtained by the manufacturing method of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. Further, the dimensional ratios in the drawings are exaggerated by the convenience of explanation, and may differ from the actual ratios.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view schematically showing the outline of a laminated battery which is one embodiment of a battery of the present invention. FIG. In this specification, the laminate-type lithium ion secondary battery shown in Fig. 1 is described in detail as an example, but the technical scope of the present invention is not limited to this form. The heat resistant layer, which is a component of the lithium ion secondary battery of the present embodiment, is omitted in FIG.

As shown in Fig. 1, the stacked lithium ion secondary battery 10 of the present embodiment has a structure in which a power generating element 17 is housed and sealed by using a battery exterior material 22. As shown in Fig. Here, the power generation element 17 includes a negative electrode having a negative electrode active material layer 12 formed on both surfaces of the negative electrode collector 11 (one side for the lowermost layer and the uppermost layer of the power generating element), an electrolyte layer (separator) And a positive electrode having a positive electrode active material layer 15 formed on both sides of the positive electrode active material layer 14. The negative electrode active material layer 12 on one side of one negative electrode and the positive electrode active material layer 15 on one side of the one positive electrode adjacent to the one negative electrode face each other with the electrolyte layer (separator) 13 interposed therebetween And a plurality of positive electrodes, an electrolyte layer (separator) 13, and positive electrodes are stacked in this order.

Thus, the adjacent negative electrode active material layer 12, the electrolyte layer (separator) 13, and the positive electrode active material layer 15 constitute one unit cell layer 16. Therefore, the lithium ion secondary battery 10 of the present embodiment can have a structure in which a plurality of unit cell layers 16 are laminated and electrically connected in parallel. The negative electrode active material layer 12 is formed on only one side of the outermost negative electrode collector 11a located on the outermost layers of both sides of the power generating element 17. In Fig. 1, the arrangement of the negative electrode plate and the positive electrode plate may be changed. At this time, the outermost layer positive electrode current collector (not shown) is positioned on both outermost layers of the power generating element 17 and the positive electrode active material layer 15 is formed on only one side of the outermost positive electrode current collector do.

The negative electrode current collecting plate 18 and the positive electrode current collecting plate 19 which are electrically connected to the above electrodes (positive electrode and negative electrode) are connected to the positive electrode terminal lead 20 and the negative electrode terminal lead 21, respectively, And is attached to the whole body 11 and the positive electrode current collector 14 by ultrasonic welding, resistance welding, or the like. The negative electrode current collecting plate 18 and the positive electrode current collecting plate 19 which are electrically connected to the negative electrode collector 11 and the positive electrode collector 14 are exposed to the outside of the battery casing 22 .

2 is a schematic cross-sectional view of the laminated electrode body 30 of the lithium ion secondary battery of the present embodiment. The laminated electrode assembly 30 corresponds to an enlarged view of the unit cell layer 16 shown in Fig. 1, and the separator 31 constitutes the electrolyte layer 13 together with the electrolyte. 2, the laminated electrode assembly 30 has a separator 31 between the negative-electrode active material layer 12 and the positive-electrode active material layer 15. The laminated electrode assembly 30 also has a heat resistant layer 32 that is sandwiched between the active material layers (the negative electrode active material layer 12 and the positive electrode active material layer 15) and the separator 31.

&Lt; Production method of nonaqueous electrolyte secondary battery >

In the method for producing a lithium secondary battery of the present embodiment, first, a laminated electrode body is obtained. The laminated electrode body is constituted by stacking a positive electrode active material layer, a negative electrode active material layer, a separator, and a heat-resistant layer disposed between the positive electrode active material layer or the negative electrode active material layer and the separator as described above. The laminated electrode body is formed by thermally compressing a laminated body in which a heat-resistant precursor layer is laminated between an active material layer and a separator at a predetermined temperature. The heat-resistant precursor layer of the present embodiment includes a first particle and a second particle having a melting point higher than that of the first particle. The temperature of the heat compression in this embodiment is higher than the melting point of the first particles and lower than the melting point of the second particles and the separator. That is, the heat-resistant layer is formed by melting the first particles in the heat-resistant precursor layer by thermally compressing the laminate. Hereinafter, the method of manufacturing the lithium secondary battery of the present embodiment will be described in detail.

The &quot; laminated electrode body &quot;

(1) First, in order to form a heat-resistant precursor layer on a positive electrode active material layer, a negative electrode active material layer, or a separator, a negative electrode active material layer, a positive electrode active material layer, and a separator are prepared. Hereinafter, the constitution of each layer and the constitution of the slurry for forming each layer will be described.

[Negative pole]

And the negative electrode has a structure in which the negative electrode active material layer 12 is formed on the surface of the negative electrode collector 11.

In the present embodiment, the slurry for forming the negative electrode active material layer 12 (hereinafter referred to as the negative electrode active material layer slurry) includes a negative electrode active material and, if necessary, a conductive additive, a binder and a solvent for enhancing electrical conductivity.

(Negative current collector)

The negative electrode collector 11 is made of a conductive material. The conductive material constituting the current collector is not particularly limited as long as it has conductivity, and conventionally well-known materials such as metal and conductive polymer can be suitably used. Concretely, at least one or more kinds selected from the group consisting of Fe, Cr, Ni, Mn, Ti, Mo, V, Nb, Al, Cu, Ag, Au, And the current collector material such as stainless steel made of an alloy can be preferably used. Further, in the present embodiment, a plating material of a clad material of Ni and Al, a clad material of Cu and Al, or a combination of these current collector materials can be preferably used. Alternatively, the current collector may be formed by coating Al, which is another current collector material, on the surface of the metal (excluding Al) as the current collector material. Further, in some cases, a current collector obtained by bonding two or more metal foils, which are the current collector materials, may be used.

The thickness of the current collector is not particularly limited, but it is usually 1 to 100 mu m, preferably 1 to 50 mu m, in any one of the current collector.

(Negative electrode active material)

The negative electrode active material used in the present embodiment is a carbon-based conductive material (carbon material) capable of reversibly intercalating and deintercalating lithium ions. Examples of such carbon materials include Ketjen black, Balkan, acetylene black, black pearl, carbon carriers heat-treated at high temperatures in advance, carbon nanotubes, carbon nanohorns, and carbon fibers.

In some cases, as the negative electrode active material, a metal material such as lithium metal, a lithium-transition metal composite oxide such as lithium-titanium composite oxide (lithium titanate: Li4Ti5O12), and other conventionally known negative electrode active materials may be used in combination.

The average particle diameter of the negative electrode active material contained in the negative electrode active material layer is not particularly limited, but is preferably 1 to 20 占 퐉, more preferably 1 to 5 占 퐉 in view of high output. In the present specification, the term &quot; particle diameter &quot; means the maximum distance L among distances between any two points on the contour of the particle. As the value of the &quot; average particle diameter &quot;, a value calculated as an average value of the particle diameters observed in several to several tens of fields by employing observation means such as a scanning electron microscope (SEM) or a transmission electron microscope do. The particle diameters and average particle diameters of the other constituent components can be similarly defined.

(Challenge preparation)

The conductive agent refers to an additive compounded to improve the conductivity. The conductive auxiliary which can be used in the present embodiment is not particularly limited, and conventionally known forms can be appropriately referred to. For example, carbon materials such as carbon black such as acetylene black, graphite, and carbon fiber can be cited. When the active material layer contains a conductive auxiliary agent, an electronic network inside the active material layer is effectively formed, and the output characteristics of the battery can be improved. Although the carbon material used as the negative electrode active material in this embodiment has conductivity itself, the use of the conductive additive is not necessarily required in such a case.

(bookbinder)

The binder is added to the active material layer for the purpose of bonding the active materials or binding the active material to the current collector or the conductive auxiliary to maintain the electrode structure (three-dimensional network).

The binder is not particularly limited, and examples include the following materials. Cellulose acetate and carboxymethylcellulose (CMC), thickeners such as polyethylene, polypropylene, polyethylene terephthalate (PET), polyether nitrile, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, Butadiene rubber, styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene propylene rubber, ethylene-propylene-diene copolymer, styrene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene- And hydrogenated products thereof, thermoplastic resins such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl Vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (VDF-HFP fluororubber), vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluororubber), fluorine resins such as polytetrafluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (VDF-HFP-TFE fluororubber), vinylidene fluoride-pentafluoropropylene fluororubber (VDF-PFP fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber (VDF-PFP-TFE fluororubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluororubber (VDF-PFP-TFE fluororubber), vinylidene fluoride- Vinylidene fluoride-based fluorine rubber such as PFMVE-TFE fluorine rubber) and vinylidene fluoride-chlorotrifluoroethylene fluororubber (VDF-CTFE fluororubber), acrylic resin, polyurethane resin and urea Resin. These may be used alone or in combination of two or more.

(additive)

Other additives that can be included in the negative electrode active material layer 12 of the present embodiment include, for example, ion conductive polymers.

(menstruum)

The negative electrode active material layer slurry of the present embodiment preferably contains a solvent.

The solvent used for the slurry for the negative electrode active material layer is not particularly limited, but N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide, methanol, ethanol, isopropanol, Can be used. When an aqueous solvent such as water is used, for example, carboxymethylcellulose (CMC) or the like may be added. The amount of the solvent is not particularly limited, but is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, and still more preferably 10 to 75% by mass with respect to the total mass of the slurry.

[Method of forming negative electrode (negative electrode active material layer)] [

The negative electrode can be produced by coating and drying the negative electrode active material layer slurry on the surface of the negative electrode collector 11. For example, as a method for producing the negative electrode, an electrode slurry is prepared by dispersing an electrode material (a negative electrode active material, a conductive auxiliary agent and a binder) in a solvent, applying the slurry to one or both surfaces of the current collector, , The negative electrode can be manufactured.

The mixing ratio of the above components that can be contained in the negative electrode active material layer 12 is not particularly limited. The compounding ratio can be adjusted by appropriately referring to a known knowledge of the nonaqueous electrolyte secondary battery. The thickness of the negative electrode active material layer is not particularly limited, and conventionally known knowledge about the battery can be appropriately referred to. For example, the thickness of the negative electrode active material layer is about 2 to 100 mu m.

[Positive]

The positive electrode has a structure in which the positive electrode active material layer 15 is formed on the surface of the positive electrode collector 14. [

In the present embodiment, the slurry for forming the positive electrode active material layer (hereinafter referred to as the slurry for the positive electrode active material layer) includes a positive electrode active material and, if necessary, a conductive additive for improving electrical conductivity, a binder and a solvent. As for the components other than the positive electrode active material, the negative electrode active material layer 12 may have the same shape as described above.

(Positive electrode collector)

The positive electrode current collector 14 is made of a conductive material. As for the kind and thickness of the conductive material constituting the positive electrode current collector, the same configuration as that described above can be adopted for the negative electrode collector 11, and detailed description thereof is omitted here.

(Positive electrode active material)

The positive electrode active material is not particularly limited as long as it is a material capable of intercalating and deintercalating lithium, and a positive electrode active material usually used in a lithium ion secondary battery may be used. Specifically, Li-Mn composite oxide such as LiMn2O4, Li-Ni composite oxide such as LiNiO2, Li-Ni-Mn composite oxide such as LiNi0.5Mn0.5O2, and the like are preferable. Based composite oxides. In some cases, two or more kinds of positive electrode active materials may be used in combination.

[Formation method of positive electrode (positive electrode active material layer)] [

The positive electrode can be produced by applying and drying a slurry for a positive electrode active material layer on the surface of the positive electrode collector 14. For example, as a production method of the positive electrode, an electrode slurry is prepared by dispersing an electrode material (positive electrode active material, conductive auxiliary agent and binder) in a solvent, and the slurry is coated on one or both surfaces of the current collector, The positive electrode can be produced.

The compounding ratio of the above components that can be contained in the positive electrode active material layer 15 is not particularly limited. The compounding ratio can be adjusted by appropriately referring to a known knowledge of the nonaqueous electrolyte secondary battery. The thickness of the positive electrode active material layer is not particularly limited, and conventionally well-known knowledge about the battery can be appropriately referred to. For example, the thickness of the positive electrode active material layer is about 2 to 100 mu m.

[Separator]

The separator is interposed between the positive electrode active material layer and the negative electrode active material layer and has a role of retaining a short-circuit preventing or electrolytic solution accompanied by the contact of the positive electrode active material to secure conductivity.

As the separator, a porous sheet separator, a nonwoven fabric separator, or the like made of a polymer that absorbs, holds, or supports an electrolyte can be used. Examples of the porous sheet separator include polyolefins such as polyethylene (PE) and polypropylene (PP), stacked layers having a three-layer structure of PP / PE / PP, polyethylene terephthalate (PET), polyimide, polyvinyl fluoride (PVdF-HFP), or a microporous membrane made of glass fiber or the like can be given. As the material of the nonwoven fabric separator, conventionally known materials such as polyolefin, polyimide, or aramid resin such as rayon, acetate, nylon, polyester, polypropylene or polyethylene can be used.

The separator preferably has a melting point of 120 to 300 캜. More preferably 125 to 200 占 폚, still more preferably 125 to 180 占 폚, particularly preferably 130 to 170 占 폚, and most preferably 130 to 160 占 폚.

Moreover, there is no restriction | limiting in particular also about the thickness of a separator, The conventionally well-known knowledge about a battery can be referred suitably. The thickness of the separator is, for example, preferably 1 to 50 占 퐉, more preferably 2 to 30 占 퐉, and still more preferably 5 to 25 占 퐉.

 (2) Next, a heat-resistant precursor layer is formed on the positive electrode active material layer, the negative electrode active material layer or the separator. Hereinafter, the structure of the heat-resistant precursor layer and the constitution of the slurry for forming the heat-resistant precursor layer will be described.

[Heat-resistant precursor layer]

In the present embodiment, the method of forming the heat-resistant precursor layer is not particularly limited, and can be formed, for example, by applying a slurry (hereinafter referred to as a heat-resistant precursor layer slurry) for forming the heat-resistant precursor layer on an electrode or a separator. Hereinafter, a method of forming a heat-resistant precursor layer using a slurry for a heat-resistant precursor layer will be exemplified.

In the present embodiment, the slurry for a heat-resistant precursor layer includes a first particle, a second particle having a melting point higher than that of the first particle, and a solvent. As a preferred embodiment, the slurry for a heat-resistant precursor layer further comprises a third particle having a melting point higher than the melting point of the first particle and lower than the melting point of the second particle. Further, the slurry for the heat-resistant precursor layer preferably contains a binder.

(First particle)

The first particles used in the present embodiment may be any particles that can be melted by thermal compression and may be, for example, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl acetate, polystyrene (PS), acrylonitrile / styrene resin (AS), acrylonitrile / butadiene / styrene resin (ABS), methacrylic resin (PMMA), polyamide (PA), polyacetal, polyethylene terephthalate Butylene terephthalate (PBT) and ethylene-vinyl acetate copolymer, and modified particles and derivatives thereof. Of these, polyolefin-based particles such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl acetate and ethylene-vinyl acetate copolymer are more preferable. The first particles may be used singly or in combination of two or more kinds.

The first particles preferably have a melting point of 60 to 120 캜. More preferably 60 to 110 占 폚, still more preferably 60 to 100 占 폚, particularly preferably 60 to 90 占 폚, and most preferably 60 to 80 占 폚. By setting the melting point within the above range, the first particles can be melted rapidly by thermal compression, and the junction of the active material layer and the separator can be formed. The melting point means a melting temperature (transition temperature) measured using a differential scanning calorimeter (DSC) in accordance with JIS-K7121. For example, the melting point of the particles is measured by TG-DTA6300 manufactured by Seiko Instruments (SII). When a material having no melting point is used, the softening point may be handled as a melting point. In this case, the heat distortion temperature is measured by the JIS-K7191 method.

The content of the first particles in the slurry for the heat-resistant precursor layer is not particularly limited and may be appropriately adjusted so as to have a content as described below with respect to the solid content (100 mass%) forming the heat-resistant precursor layer (heat resistant layer).

The particle diameter of the first particles is not particularly limited as long as the particle diameter is smaller than the thickness of the heat resistant layer. For example, the particle diameter is preferably from 4/5 to 1/100 of the thickness of the heat resistant layer, More preferably from 50/50 to 50/50, and even more preferably from 1/2 to 1/25. For example, the average particle size of the first particles is preferably 0.3 to 10 占 퐉 from the viewpoint that the bonding points of the first particle and the active material layer or the separator are dotted. Further, it is preferably in the order of 0.3 to 6 占 퐉 and 0.35 to 5 占 퐉. More preferably, it is 0.35-3 micrometers, More preferably, it is 0.4-2 micrometers.

(Second particle)

The second particles used in the present embodiment are not particularly limited as long as they have a melting point higher than that of the first particles and are not melted by thermal compression. For example, when the melting temperature (transition temperature) measured by the JIS-K7121 method is 120 deg. C or higher, or a heat distortion temperature measured by the JIS-K7191 method of 120 deg. C or higher, or no heat distortion temperature. Therefore, even after the thermal compression, the second particle maintains the shape of the particle, and has a function as an insulating layer between the active material layer and the separator. Further, even under a high temperature, since the particle shape is maintained, even when the internal temperature of the battery rises, it acts as a quenching layer to prevent internal short circuit.

The second particles are not particularly limited as long as they do not flow at a temperature lower than 120 占 폚, are electrically non-conductive, are electrochemically stable, and stable to an electrolytic solution or a solvent (dispersion medium). Examples thereof include inorganic particles (inorganic powder) of non-electrically conductive (electrically insulating), organic particles (organic powder) having a melting point of 120 ° C or more, and particles of crosslinked polymer. The "particles of organic particles having a melting point of not lower than 120 ° C. and particles of the crosslinked polymer" means that the melting temperature (transition temperature) measured using DSC is 120 ° C. or higher in accordance with JIS-K7121.

Examples of the non-electrically conductive inorganic particles used as the second particles include oxide particles such as iron oxide, SiO2, Al2O3, TiO2 and BaTiO2, nitride particles such as aluminum nitride and silicon nitride, calcium fluoride, barium fluoride, Poorly soluble ionic crystal grains, covalent crystal grains such as silicon and diamond, and clay particles such as montmorillonite. The surface of conductive particles such as metal particles, oxide particles such as SnO2, tin-indium oxide (ITO), carbonaceous particles such as carbon black and graphite may be coated with a material having electrical insulation A material constituting conductive inorganic particles, a material constituting organic particles having a melting point of not lower than 120 占 폚, a material constituting crosslinked polymer particles, etc.) may be used.

Examples of the organic particles having a melting point of not less than 120 캜 used as the second particles include particles of polyethylene (limited to those having a high melting point in ultrahigh molecular weight or the like), polypropylene, polystyrene, polyamide and polyester. Examples of the particles of the crosslinked polymer used as the second particle include crosslinked polymethyl methacrylate, crosslinked polystyrene, crosslinked polydivinylbenzene, crosslinked styrene-divinylbenzene copolymer, polyimide, melamine resin, phenol resin, Guanamine-formaldehyde condensate, and the like. These organic particles and the organic resin (polymer) constituting the particles of the crosslinked polymer may be used in the form of a mixture, a modified product, a derivative, a copolymer (a random copolymer, an alternate copolymer, a block copolymer, Copolymer) or a crosslinked material (for a material other than the crosslinked polymer). The second particles may be used singly or in combination of two or more kinds.

The second particle preferably has a melting point of 120 캜 or higher. More preferably 180 ° C or higher, further preferably 200 ° C or higher, particularly preferably 400 ° C or higher. The upper limit of the melting point of the second particles is not particularly limited. By setting the melting point within the above-mentioned range, the second particles can exist as particles in the heat resistant layer without being melted by thermal compression, and can act as an isolation point between the active material layer and the separator.

The content of the second particles in the slurry for the heat-resistant precursor layer is not particularly limited and may be suitably adjusted so as to have a content as described below with respect to the solid content (100 mass%) forming the heat-resistant precursor layer (heat resistant layer).

The particle diameter of the second particles is not particularly limited as long as the particle diameter is smaller than the thickness of the heat resistant layer. For example, the particle diameter is preferably 4/5 to 1/100 of the thickness of the heat resistant layer, More preferably from 50/50 to 50/50, and even more preferably from 1/2 to 1/25. For example, the average particle diameter of the second particles is not particularly limited, but is preferably 0.3 to 10 占 퐉 from the viewpoint that the second particles are separated from the active material layer or the separator by an isolated point. More preferably, it is 0.35-3 micrometers, More preferably, it is 0.4-2 micrometers.

(Third particle)

In the present embodiment, it is preferable that the slurry for the heat-resistant precursor layer further comprises third particles having a melting point higher than the melting point of the first particles and lower than the melting point of the second particles. Since the heat resistant layer includes the third particles, when the internal temperature of the battery rises, the third particles can be melted to fill the voids in the heat resistant layer to increase the internal resistance, thereby having a shutdown function. The melting point of the third particles means a melting temperature (transition temperature) measured using a differential scanning calorimeter (DSC) in accordance with JIS-K7121.

As a 3rd particle used by this embodiment, if melting | fusing point is higher than 1st particle | grain, and melting | fusing point is lower than 2nd particle | grain, it will not specifically limit. As the third particles, for example, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl acetate, polystyrene (PS), acrylonitrile / styrene resin (AS), acrylonitrile / A thermoplastic resin such as a butadiene / styrene resin (ABS), a methacrylic resin (PMMA), a polyamide (PA), a polyacetal, a polyethylene terephthalate (PET), a polybutylene terephthalate (PBT), or an ethylene- Or derivatives thereof, and the like. Of these, polyolefin-based particles such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl acetate and ethylene-vinyl acetate copolymer are more preferable. As the third particles, they may be used singly or in combination of two or more kinds.

The third particles preferably have a melting point of 100 to 180 캜. More preferably 110 to 175 占 폚, still more preferably 110 to 170 占 폚, particularly preferably 120 to 160 占 폚, and most preferably 120 to 150 占 폚. By setting the melting point within the above range, the third particles can exist as particles in the heat resistant layer without being melted by thermal compression, and can act as an isolation point between the active material layer and the separator. Further, when the internal temperature of the battery rises, the third particles are melted to increase the internal resistance by filling the voids in the heat resistant layer, so that the shutdown function can be exhibited.

The content of the third particles in the slurry for the heat-resistant precursor layer is not particularly limited and may be suitably adjusted so as to have a content as described below with respect to the solid content (100 mass%) forming the heat-resistant precursor layer (heat-resistant layer).

The particle diameter of the third particles is not particularly limited as long as the particle diameter is smaller than the thickness of the heat resistant layer. For example, the particle diameter is preferably 4/5 to 1/100 of the thickness of the heat resistant layer, More preferably from 50/50 to 50/50, and even more preferably from 1/2 to 1/25. For example, the average particle diameter of the third particles is not particularly limited, but is preferably 0.3 to 10 mu m from the viewpoint of exhibiting the shutdown function. More preferably, it is 0.35-3 micrometers, More preferably, it is 0.4-2 micrometers.

(bookbinder)

The slurry for a heat-resistant precursor layer in this embodiment preferably includes a binder. The first particles and the second particles of the heat-resistant layer to be finally formed may be fused to each other by a binder. The first particles and the second particles are fused to each other by melting the first particles, but by including the binder, the first particles and the second particles can be fused more firmly at multiple points. The binder becomes dissolved or dispersed in the heat-resistant precursor layer.

The state in which the binder is dissolved in the heat-resistant precursor layer means the form of the binder in the heat-resistant precursor layer formed by using the slurry for the heat-resistant precursor layer in which the binder component is dissolved in the slurry for the heat-resistant precursor layer. In this form, the binder is not particularly limited as long as it has a function of fusing the components of the heat-resistant precursor layer. At this time, when preparing the slurry for the heat-resistant precursor layer, the solvent for dissolving the binder is appropriately selected without dissolving the first particles, the second particles and the third particles as constituent components in the heat-resistant precursor layer. The shape of the binder is similar to that of the heat-resistant precursor layer when the heat-resistant layer is formed by thermally compressing the heat-resistant precursor layer.

The state in which the binder is dispersed in the heat-resistant precursor layer means the form of the binder in the heat-resistant precursor layer formed by using the slurry for the heat-resistant precursor layer in a state in which the binder component is not dissolved in the slurry for the heat- . In this form, the binder is interposed between the components of the heat-resistant precursor layer and may have an action to suppress coagulation or the like, and its shape is not particularly limited, but it has, for example, a particulate form. At this time, when preparing the slurry for the heat-resistant precursor layer, the first particles, the second particles, the third particles, and the solvent that does not dissolve the binder are appropriately selected as constituent components in the heat-resistant precursor layer.

In the case where the binder is dispersed in the heat-resistant precursor layer, the average particle diameter of the binder is not particularly limited as long as it is interposed between the first particle, the second particle and the third particle, And is preferably 50 to 500 nm. More preferably 70 to 300 nm, further preferably 70 to 300 nm, particularly preferably 100 to 200 nm.

The melting point of the binder is not particularly limited, but is preferably 150 ° C or higher. More preferably 180 deg. C or higher, and still more preferably 240 deg. C or higher. The upper limit of the melting point of the binder is not particularly limited.

The shape of the binder in the heat-resistant layer formed by thermally compressing the heat-resistant precursor layer is equivalent to that in the above-mentioned heat-resistant precursor layer.

The binder used in the present embodiment is not particularly limited as long as the particles can be adhered or dispersed well and is electrochemically stable. Examples of the binder include thickeners such as cellulose and carboxymethylcellulose (CMC) Polypropylene, polyethylene terephthalate (PET), polyether nitrile, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyvinyl chloride, styrene butadiene rubber (SBR) A thermoplastic resin such as butadiene rubber, ethylene propylene rubber, ethylene-propylene-diene copolymer, styrene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-isoprene-styrene block copolymer and hydrogenated product thereof, polyvinylidene fluoride PVdF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexapol Propylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene- Fluorine resins such as fluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluororubber), vinylidene fluoride-hexafluoropropylene (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-pentafluoropropylene- (VDF-PFP-TFE fluorine rubber), vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene fluororubber (VDF-PFMVE-TFE fluorine rubber), and bis Fluoride-chloro-trifluoro-ethylene-based fluorine rubber (VDF-CTFE-based fluorine rubber), and the vinylidene fluoride-based fluorine rubber, acrylic resin, polyurethane resin, and urea resin, etc. and the like. These may be used alone or in combination of two or more. In the production process, these binders may be used in the form of an organic solvent in which a binder such as N-methyl-2-pyrrolidone (NMP) is soluble. In addition, a dispersant may be used to prevent aggregation of the first particles and the second particles. As the dispersing agent, a compound having a dispersing action such as polyoxystearylamine can be used.

The content of the binder is preferably 0.01 to 25 mass% with respect to the total solid content (100 mass%) of the slurry for the heat-resistant precursor layer. More preferably from 0.1 to 20% by mass, still more preferably from 0.3 to 15% by mass, and particularly preferably from 0.5 to 10% by mass. By making the content of the binder fall within the above range, the bonding point and the separation point of the active material layer and the separator can be present dotted on the bonding surface.

(menstruum)

The slurry for a heat-resistant precursor layer in this embodiment includes a solvent.

The solvent used in the slurry for the heat-resistant precursor layer is not particularly limited as long as it does not dissolve the particles to be used. Examples of the solvent include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, Ethanol, isopropanol, water and the like can be used. The solvent used in the slurry for the heat-resistant precursor layer needs to appropriately select a solvent that does not dissolve the first particles, the second particles and the third particles, which are constituent components in the heat-resistant precursor layer. The amount of the solvent is not particularly limited, but is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, and still more preferably 10 to 75% by mass with respect to the total mass of the heat-resistant precursor layer slurry.

As described above, the slurry for a heat-resistant precursor layer of this embodiment contains a first particle, a second particle and, if necessary, a third particle. The melting point of these particles becomes higher in the order of the first particle, the third particle and the second particle in this order. The compounding ratio of the above-mentioned components that can be contained in the slurry for the heat-resistant precursor layer is not particularly limited, but is preferably blended so as to be a preferable constitution of the heat-resistant precursor layer and the heat-resistant layer to be described later.

(Formation method of heat resistant precursor layer)

The laminated body of this embodiment forms a heat resistant precursor layer between an active material layer and a separator. Therefore, the heat-resistant precursor layer is formed on the negative electrode active material layer, the positive electrode active material layer, or the separator by using the slurry for the heat-resistant precursor layer.

The heat-resistant precursor layer can be produced by coating and drying a slurry for a heat-resistant precursor layer on the surface of the negative-electrode active material layer, the positive electrode active material layer, or the separator. For example, as a manufacturing method of the heat-resistant precursor layer, a constituent material (for example, first particles, second particles and a binder) of a heat-resistant precursor layer is dispersed in a solvent to prepare a slurry for a heat-resistant precursor layer, And then drying the slurry. The drying of the heat-resistant precursor layer is not particularly limited, but is preferably performed at a temperature lower than the melting point of the first particles, more preferably 25 to 60 ° C, and further preferably 30 to 55 ° C.

As described above, the heat-resistant precursor layer according to the present embodiment includes the first particles, the second particles and, if necessary, the third particles. The melting point of these particles is high in the order of the first particle, the third particle and the second particle in this order.

The content of the first particles in the heat-resistant precursor layer (heat-resistant layer) is preferably contained in an amount of 1 to 50 mass% with respect to the total solid content (100 mass%) of the heat-resistant precursor layer (heat-resistant layer). More preferably from 1.2 to 45% by mass, still more preferably from 1.5 to 40% by mass, and particularly preferably from 2 to 30% by mass. By setting the content of the first particles within the above range, the junction point of the first particle and the active material layer or the separator can be dotted on the bonding surface, and the ion conduction resistance by the heat resistant layer can be reduced.

The second particles in the heat-resistant precursor layer (heat-resistant layer) is preferably 50 to 99 mass% with respect to the total solid content (100 mass%) of the heat-resistant precursor layer (heat-resistant layer). More preferably 55 to 98.5% by mass, still more preferably 65 to 98% by mass, and particularly preferably 70 to 97% by mass. By making the content of the second particles fall within the above range, the isolation point between the active material layer and the separator can be dotted on the joint surface, and when the internal temperature of the battery rises, it can have a role of short circuit prevention.

The content of the third particles in the heat-resistant precursor layer (heat-resistant layer) is preferably in the range of 1 to 50 mass% with respect to the total solid content (100 mass%) of the heat-resistant precursor layer By weight. More preferably 2 to 49 mass%, further preferably 3 to 48 mass%, particularly preferably 5 to 47 mass%, and most preferably 7 to 30 mass%. By setting the content of the third particles within the above range, the isolation point between the active material layer and the separator can be dotted on the bonding surface, and the shutdown function can be exhibited when the battery internal temperature rises.

The content of the binder in the heat-resistant precursor layer (heat-resistant layer) is preferably 0.01 to 25 mass% with respect to the total solid content (100 mass%) of the heat-resistant precursor layer (heat-resistant layer). More preferably from 0.1 to 20% by mass, still more preferably from 0.3 to 15% by mass, and particularly preferably from 0.5 to 10% by mass. By making the content of the binder fall within the above range, the bonding point and the separation point of the active material layer and the separator can be present dotted on the bonding surface.

The thickness of the heat-resistant precursor layer is not particularly limited, but is preferably 1 to 20 占 퐉 from the viewpoint of isolating the separator from the active material layer. More preferably 2 to 14 占 퐉, still more preferably 3 to 10 占 퐉, particularly preferably 4 to 8 占 퐉.

(3) Next, the heat-resistant precursor layer is sandwiched between the active material and the separator to form a laminate.

After the heat-resistant precursor layer is formed, for example, when the heat-resistant precursor layer is formed on the negative electrode active material layer, the separator is laminated on the heat-resistant precursor layer to form a laminate. When the heat-resistant precursor layer is formed on the separator, the negative-electrode active material or the positive-electrode active material is laminated on the heat-resistant precursor layer to form a laminate. Then, the lamination is repeated to obtain a laminate in which a desired number of layers of the heat-resistant precursor layer are sandwiched between the active material layer and the separator.

(4) A laminate having a heat-resistant precursor layer sandwiched between the active material layer and the separator is obtained, and then the laminate is thermally compressed to a predetermined temperature.

That is, the heat-resistant precursor layer including the first particle and the second particle having a melting point higher than that of the first particle is held by the active material layer and the separator so as to be higher than the melting point of the first particle, To a temperature lower than the melting point of the particles and the melting point of the separator, thereby producing a heat resistant layer.

In the present embodiment, by thermally compressing the laminate, the first particles in the heat-resistant precursor layer of the laminate are melted to form a heat-resistant layer. Therefore, the heat compression temperature may be a temperature higher than the melting point of the first particles and lower than the melting point of the second particles and the separator. By setting the temperature within this range, the active material layer and the separator can have a junction and an isolation point via the heat-resistant layer, and the effect of the present invention is exerted. The temperature of the specific heat compression is not particularly limited, but is preferably 80 ° C or more and less than 130 ° C, for example. More preferably 85 to 125 占 폚, still more preferably 90 to 120 占 폚, particularly preferably 100 占 폚 to 120 占 폚, and most preferably 100 to 115 占 폚. When the heat-resistant precursor layer contains the third particles, the heat compression temperature may be higher than the melting point of the first particles and lower than the melting point of the third particles and the separator. By setting the temperature within this range, when the internal temperature of the battery rises, the third particles are melted and a shutdown function is exerted. By the above-described thermal compression, a power generating element having high adhesion between the separator and the active material layer can be manufactured by a simpler method.

After the thermal compression, if necessary, drying or the like is carried out to obtain a laminated electrode body.

The drying of the layered product is not particularly limited, but is preferably performed at a temperature lower than the melting point of the first particles, more preferably 25 to 60 ° C, further preferably 30 to 55 ° C, Deg.] C to 10 hours, under vacuum.

As described above, the heat-resistant layer 32 is obtained by thermally compressing the heat-resistant precursor layer containing two particles having different melting points to a predetermined temperature. One of the particles of the heat-resistant precursor layer is melted by thermal compression, and the molten particles are bonded to each other via the heat-resistant layer between the active material layer and the separator. In addition, since the other particle exists as a particle | grain in a heat resistant layer after thermal compression, it becomes an isolation point which isolate | separates an active material layer and a separator. The shape of the first particles is different between the heat-resistant layer and the heat-resistant precursor layer, and the shape of the second particles and the content of each component are the same in the heat-resistant layer and the heat-resistant precursor layer. In the case where the heat resistant layer includes the third particles, the shape of the third particles may be changed after the internal temperature of the battery is once raised.

3 (a) is a schematic cross-sectional view schematically showing the heat resistant layer 42 in the laminated electrode body 40 of the lithium ion secondary battery of the present embodiment. A negative electrode 41, a heat resistant layer 42, a separator 43, and a positive electrode 44 are laminated in this order on the laminated electrode member 40. The heat resistant layer 42 includes the region 51 in which the first particles are melted and the second particles 52 and the binder 53. The heat resistant layer 42 includes the negative electrode 41 and the separator 43, And the heat resistant layer 42 adheres at the junction point 51a of the melted region 51 and is isolated from the isolation point 52a by the second particle 52. [ 3B shows a laminated electrode member 40 of a lithium ion secondary battery according to the embodiment of FIG. 3A in which the first particle-molten region 51 is formed in the heat resistant layer 42, A third particle 54 in addition to the first particle 52, the second particle 52, and the binder 53. In this case, 3 (a), the heat resistant layer 42 is disposed between the negative electrode 41 and the separator 43, and the heat resistant layer 42 is located between the junction point of the region 51 in which the first particles are melted 51a and separated from the isolation point 52a by the second particle 52 and the isolation point 54a by the third particle 54. [ In the present embodiment (Figs. 3A and 3B), the region 51 in which the first particles are melted is also present in the heat-resistant layer, whereby the peel strength of the heat-resistant layer is improved . In the present embodiment (Figs. 3A and 3B), since the first particles can be bonded at the junction point 51a of the melted region 51, The output is improved as compared with the case of having an adhesive layer.

As a method of discriminating the nonaqueous electrolyte secondary battery obtained by the method of the present embodiment, for example, a method of cutting the laminated electrode body and observing the sectional view by SEM can be mentioned. That is, in the cross-sectional view, another layer exists between the active material layer and the separator, and the layer has a portion for adhering the particulate portion and the particulate component. When the particulate portion in the layer is constituted of a plurality of components, the melting point of each particulate portion is measured by differential scanning calorimetry (DSC), or the cross-section is observed with a microscope while slowly heating, By measuring the melting temperature, it is possible to belong to which constituent particles of the layer are constituted. In addition, the above-described method can be applied also as a method of discriminating the region where the particle component is melted and the region of the binder in the layer. The content of each component can be determined by analyzing the material of each site by 1H-NMR or the like, calculating the mass using the volume of the cross-sectional area and the density of the material, The content of the component can be calculated.

The thickness of the heat resistant layer formed as described above is not particularly limited, but it is preferably 1 to 10 占 퐉. Moreover, it is preferable in order of 1-9 micrometers and 1.5-8 micrometers. More preferably 2 to 7 占 퐉, still more preferably 3 to 6 占 퐉, particularly preferably 4 to 5 占 퐉.

"battery"

After the laminated electrode body having the heat resistant layer was obtained as described above, the positive electrode and the negative electrode were bonded together to weld the leads, and the laminated electrode body was taken out of the leads of the negative electrode. Bag, etc.), an electrolyte is injected by the main liquid machine, and the end portion is sealed under reduced pressure to form a battery.

[Home Edition]

The collector plate (positive collector plate 18 and negative collector plate 19) may be made of aluminum, copper, nickel, stainless steel, an alloy thereof, or the like. These are not particularly limited, and a well-known material conventionally used as a current collector plate may be used. In the positive electrode current collecting plate and the negative electrode current collecting plate, the same material or different materials may be used.

[Positive terminal and negative terminal lead]

The current collector is electrically connected to the current collecting plate through the positive electrode terminal lead 21 and the negative electrode terminal lead 20, respectively.

As the material of the positive and negative electrode terminal leads, a lead used in a known nonaqueous electrolyte secondary battery (lithium ion battery) can be used. The portion taken out from the battery exterior material is covered with a heat-shrinkable tube of heat-resistant insulation so as not to affect the product (for example, automobile parts, particularly, .

[Battery exterior material]

In the lithium ion secondary battery 10 of the present embodiment, the entire power generating element 17 is housed inside the battery exterior member 22 in order to prevent external impact or environmental deterioration at the time of use. As the battery exterior material 22, a laminate sheet can be used. The laminate sheet may be configured as a three-layer structure in which, for example, polypropylene, aluminum, and nylon are laminated in this order. Further, in some cases, conventionally known metal case cases can also be used as the exterior.

[Electrolyte Layer]

The electrolyte layer functions as a space partition (spacer) between the positive electrode active material layer and the negative electrode active material layer. In addition to this, it also has a function of holding an electrolyte, which is a transfer medium of lithium ions, between the gaps between the gaps in charging and discharging. In the present invention, the electrolyte absorbed and held in the separator is selected from the group consisting of a liquid electrolyte and a polymer gel electrolyte.

The liquid electrolyte is a lithium salt dissolved in a solvent as a supporting salt. Examples of the solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propionate (MP), methyl acetate (MA) ), 4-methyldioxolane (4MeDOL), dioxolane (DOL), 2-methyltetrahydrofuran (2MeTHF), tetrahydrofuran (THF), dimethoxyethane (DME), ethylene carbonate Carbonate (PC), butylene carbonate (BC) and? -Butyrolactone (GBL). These solvents may be used singly or as a mixture of two or more kinds.

Examples of the supporting salt (lithium salt) include inorganic acid anion salts such as LiPF6, LiBF4, LiClO4, LiAsF6, LiTaF6, LiSbF6, LiAlCl4, Li2B10Cl10, LiI, LiBr, LiCl, LiAlCl, LiHF2, LiSCN, LiCF3SO3, Organic acid anion salts such as Li (CF3SO2) 2N, LiBOB (lithium bisoxide borate), LiBETI [lithium bis (perfluoroethylenesulfonylimide)] and Li (C2F5SO2) 2N. The electrolytic salts may be used alone or in the form of a mixture of two or more kinds.

The gel electrolyte has a structure in which a liquid electrolyte is injected into a matrix polymer having Li + conductivity. Examples of the matrix polymer having Li + conductivity include polymer (PEO) having polyethylene oxide in the main chain or side chain, polymer (PPO) having polypropylene oxide in the main chain or side chain, polyethylene glycol (PEG), polyacrylonitrile (PAN), polymethacrylic acid ester, polyvinylidene fluoride (PVdF), a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN) ) (PMA), and poly (methyl methacrylate) (PMMA). It is also possible to use a mixture, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, etc. of the polymer and the like. Of these, PEO, PPO and their copolymers, PVdF and PVdF-HFP are preferably used. Electrolyte salts such as lithium salts can be dissolved well in such a matrix polymer.

The matrix polymer of the polymer gel electrolyte forms a crosslinked structure, so that it can exhibit excellent mechanical strength. In order to form a crosslinked structure, a polymerization initiator such as thermal polymerization, ultraviolet polymerization, radiation polymerization or electron beam polymerization is applied to a polymeric polymer (for example, PEO or PPO) for forming a polymer electrolyte by using a suitable polymerization initiator . The electrolyte may be contained in the active material layer of the electrode.

&Quot; Assembly of the battery &quot;

The assembly of the battery can be carried out by a known method and is not particularly limited, but as shown in Fig. 1, the laminated electrode body obtained above is accommodated in the casing 22. Fig. Next, the electrolytic solution is injected from an electrolyte injection port provided in the external body. After the pouring, it is preferable to seal the opening (electrolyte injection opening) of the outer casing 22 by welding or heat fusion or the like. After the opening of the external body 22 is sealed, a filling step is performed. The charging process is preferably a constant current charging of 0.01 to 5 CA, more preferably 0.15 to 3 CA, more preferably 0.2 to 2 CA, particularly preferably 0.2 to 1 CA. Further, it is preferable to carry out charging for preferably 2 to 15 hours, more preferably 3 to 12 hours, further preferably 5 to 10 hours. The temperature at the time of charging is preferably 20 to 70 占 폚, more preferably 25 to 60 占 폚, and still more preferably 25 to 50 占 폚. As the charging step, it is preferable to charge the charging step until constant current and constant voltage charging is preferable, and the charging potential is preferably 4.0 to 4.20 V, more preferably 4.1 to 4.15 V. In this way, the nonaqueous electrolyte secondary battery of the present embodiment can be obtained.

Although a stacked battery has been described above as an example, the production of a bipolar battery having a heat resistant layer can also be performed with reference to known techniques, and will be omitted here.

<Non-aqueous electrolyte secondary battery>

As described above, according to the present invention, there is provided a nonaqueous electrolyte battery comprising a positive electrode active material layer, a negative electrode active material layer, a separator, and a nonaqueous electrolyte battery including a laminated electrode body in which the positive electrode active material layer or the heat resistant layer disposed between the negative electrode active material layer and the separator are laminated Wherein the heat resistant layer comprises a first particle and a second particle having a melting point higher than that of the first particle, wherein the first particle is melted and the active material layer and the separator are bonded to each other, A nonaqueous electrolyte secondary battery is provided.

As described above, in the nonaqueous electrolyte secondary battery of the present embodiment, the first particles included in the heat resistant layer are melted and have an effect as an adhesive layer for bonding the active material layer and the separator. Further, since the second particles exist as particles in the heat resistant layer, they become isolation points for isolating the separator from the active material layer. Therefore, in the nonaqueous electrolyte secondary battery of the present embodiment, the heat resistant layer combines the effect of the adhesive layer for promoting the cell reaction and the insulating layer for preventing the short circuit.

In the nonaqueous electrolyte secondary battery of the present embodiment, it is preferable that the heat resistant layer further includes third particles having a melting point higher than the melting point of the first particles and lower than the melting point of the second particles. In the nonaqueous electrolyte secondary battery of the present embodiment, the heat resistant layer includes the third particles, so that when the battery internal temperature rises, the third particles are melted to increase the internal resistance by filling the voids in the heat resistant layer, You can have a shutdown function.

As described above, the heat-resistant layer can be recognized by thermally compressing the heat-resistant precursor layer to a predetermined temperature, as described above, by cutting the laminated electrode body and observing the cross-sectional view by SEM.

The battery thus manufactured is particularly suitable as a battery mounted on a vehicle as a motor driving power source. Here, a vehicle is, for example, an automobile that drives a wheel by a motor and another vehicle (e.g., a tram). Examples of the automobile include a completely electric vehicle not using gasoline, a hybrid vehicle such as a series hybrid vehicle and a parallel hybrid vehicle, and a fuel cell vehicle.

The battery according to the embodiment described above is not limited to the structure of the above-described laminated battery. For example, similarly to the bipolar battery, a heat-resistant layer having a junction and an isolation point is formed, and the battery output can be made excellent. Further, it may be provided as a combined battery in which a plurality of batteries themselves are combined. It goes without saying that it is of course suitable because it can be mounted on a vehicle in the case of an assembled battery.

It is needless to say that the present invention is not limited to the above-described embodiments and examples, but may be modified in various ways by those skilled in the art.

[Example]

Hereinafter, the effects of the present invention will be described using Examples and Comparative Examples, but the technical scope of the present invention is not limited to these Examples.

<Evaluation method>

Various negative electrodes were prepared and embedded in a laminate battery having LiNixMnyCozO2 (x = y = z = 1/3) as a counter electrode, and evaluation of charge-discharge cycle characteristics was carried out.

(Embodiments 1 to 4)

(1) Preparation of a positive electrode active material slurry

A slurry was prepared using NMP as a solvent at a composition ratio of LiNixMnyCozO2 (x = y = z = 1/3): HS100 (acetylene black): PVdF = 84: 10: 6.

(2) Preparation of negative electrode active material slurry

A slurry was prepared using NMP as a solvent at a composition ratio of MAG-D (artificial graphite): PVdF = 92: 8.

(3) Preparation of slurry for a heat-resistant precursor layer

(Particle diameter: 4 占 퐉, product name: Chemipel A400, manufactured by Mitsubishi Kagaku Kabushiki Kaisha) having a melting point of 73 占 폚 and alumina having a melting point of 2050 占 폚 (Product name: Chemipel WP100, manufactured by Mitsubishi Kagaku Kabushiki Kaisha) having a melting point of 148 占 폚 was used as the third particles in the composition shown in Table 1, And the total solid content was adjusted to 30% by mass. The slurry was kneaded with a planetary ball mill. In the slurry, 3% by mass of styrene butadiene rubber (SBR) (particle diameter 120 nm, no melting point, product name: BM400B, manufactured by Nippon Zeon Co., Ltd.) was added to 100% by mass of the solid content of the heat- Methyl cellulose (product name: 2200, manufactured by Dai-Sera Pharmachem Kabushiki Kaisha) was added in an amount of 1% by mass based on 100% by mass of the solid content of the heat-resistant precursor layer. As a solvent for the slurry, water was used.

(4) Preparation of the electrode

Using a doctor blade, a positive electrode slurry and a negative electrode slurry were coated on an aluminum foil and a copper foil, respectively, and dried on a hot plate at 80 DEG C for 10 minutes to prepare an electrode. To dry the water and the solvent, further vacuum drying was performed at 130 캜 for 8 hours. A slurry for a heat-resistant precursor layer having the composition ratios shown in Table 1 was applied onto the electrodes (positive electrode and negative electrode) obtained, and dried on a hot plate at 60 占 폚 for 20 minutes. The thus produced electrode was punched and pressed. The obtained heat-resistant precursor layer was 8 占 퐉.

(5) Manufacture of batteries

(Positive electrode) formed with the heat-resistant precursor layer obtained in (4), a porous film made of polypropylene (separator), and a negative electrode having the heat-resistant precursor layer obtained in (4) are laminated so that the separator is sandwiched by the heat- I got a sieve.

Each laminate was hot pressed at 110 占 폚 by adjusting the temperature so that the melting point of the first particles in the heat-resistant precursor layer <the hot press temperature <the melting point of the second particles in the porous film (separator) and the heat-resistant precursor layer> Compression). Thereafter, each laminate was vacuum-dried at 60 DEG C for 8 hours to obtain a laminated electrode body. The thickness of each layer in the laminated electrode body was 65 占 퐉 for the negative electrode active material layer, 25 占 퐉 for the separator, 55 占 퐉 for the positive electrode active material layer, and 8 占 퐉 for each of the two heat resistant layers. This laminated electrode body was mounted on an external body, an electrolyte solution was injected, and the battery was sealed to fabricate a battery.

As the electrolyte, a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) [40:60 (volume ratio)] was used as a solvent and 1M LiPF6 was used as a supporting salt (also referred to as "1M LiPF6 Means that the concentration of the supporting salt (LiPF6) in the mixture of the mixed solvent and the supporting salt is 1M). Hereinafter, the mixture of the mixed solvent and the supporting salt is referred to as &quot; electrolyte containing 1M of LiPF6 &quot;.

(6) Output measurement

The respective resistances were calculated from the voltage drop at 10 캜, 20 mA, 30 mA, 50 mA, and 100 mA for 10 seconds as a current value in an atmosphere of 25 캜 and converted into an output. The obtained output values are averaged and are shown in Table 1. The values shown in Table 1 are relative values when the output of the battery of the first comparative example is taken as 100.

(7) Peel strength measurement

(A porous film made of polypropylene) was laminated so that the heat-resistant precursor layer was sandwiched between the negative electrode and the separator, and the laminate was hot-pressed at 110 占 폚 Compression) was performed to form a heat resistant layer. The resultant laminate was subjected to a 90 DEG peeling test between the separator and the heat resistant layer, and the results are shown in Table 1. The 90 deg. Peel test was conducted in accordance with JIS Z0237 (1980) using a tester MX2-500 manufactured by Imada Co., Ltd. The peeling test speed was 300 mm / min, the peeling test piece width was 25 mm, and the peeling test temperature was room temperature (23 占 폚). The peel strength (P) of each laminate is a relative value when the peel strength in the second comparative example is 100.

(Comparative Example 1)

The positive and negative electrodes similar to those of the first to fourth embodiments were fabricated. A heat-resistant precursor layer was formed on each of the obtained electrodes (positive electrode and negative electrode) as a slurry for a heat-resistant precursor layer composition ratio shown in Table 1 and dried on a hot plate at 60 占 폚 for 20 minutes. Thereafter, in the composition ratios described in the first example of Table 1, a dispersion liquid excluding the second particles was used to form an adhesion precursor layer on the heat-resistant precursor layer, respectively. As described above, electrodes (positive electrode and negative electrode) in which a heat-resistant precursor layer and an adhesion precursor layer were laminated in this order on the electrode were obtained. The thus produced electrode was punched and pressed.

Using the electrode thus obtained, a laminate was obtained in the same manner as in Examples 1 to 4 except that a separator was held between the positive electrode and the negative electrode. At that time, the separator was laminated so as to be held by the bonding precursor layer in the form of a heat-resistant precursor layer. Thereafter, the laminate was produced in the same manner as in Examples 1 to 4 to fabricate a laminated electrode body to obtain a battery, and the output of the battery was measured. The results are shown in Table 1.

The negative electrode (the heat-resistant precursor layer and the adhesion precursor layer were formed in order on the negative electrode) and the separator (the porous film made of polypropylene) were laminated on the negative electrode, the heat-resistant precursor layer, A precursor layer, and a separator in this order, and the laminate was subjected to hot press (thermal compression) at 110 DEG C to form a heat resistant layer and an adhesive layer. The resultant laminate was subjected to a 90 DEG peeling test between the separator and the heat resistant layer, and the results are shown in Table 1.

(Comparative Example 2)

The positive and negative electrodes similar to those of the first to fourth embodiments were fabricated. A heat-resistant precursor layer was formed on each of the obtained electrodes (positive electrode and negative electrode) as a slurry for a heat-resistant precursor layer composition ratio shown in Table 1 and dried on a hot plate at 60 占 폚 for 20 minutes. The thus produced electrode was punched and pressed.

Using the electrode thus obtained, a laminate was produced in the same manner as in the first to fourth embodiments. A laminated electrode body was fabricated by the same operations as those in the first to fourth embodiments except that the laminate was subjected to hot pressing at 150 占 폚 to obtain a battery and the output of the battery was measured. 1.

The negative electrode (the heat-resistant precursor layer was formed on the negative electrode) and the separator (the porous film made of polypropylene) were stacked in this order as a negative electrode, a heat-resistant precursor layer and a separator in this order as a sample for peeling strength measurement , And the laminate was subjected to hot press (thermal compression) at 110 占 폚. The resultant laminate was subjected to a 90 DEG peeling test between the separator and the heat resistant layer, and the results are shown in Table 1.

It can be seen from Table 1 that the peel strength of the laminated electrode body having the heat resistant layer containing the first particles (first to fourth embodiments) is such that the laminated electrode body having the heat resistant layer containing no first particles The peel strength of Comparative Example is higher than that of Comparative Example. It is also understood that the battery having the heat resistant layer (the first to fourth embodiments) is superior in the output performance to the battery (comparative example 1) in which the adhesive layer and the insulating layer are formed.

10: stacked secondary battery
11: negative electrode current collector
11a: Outermost layer current collector on the negative electrode side
12: negative electrode active material layer
13: electrolyte layer
14: positive electrode current collector
15: positive electrode active material layer
16: single cell layer
17: development factors
18: negative electrode collector plate
19: positive electrode collector plate
20: negative terminal lead
21: positive terminal lead
22: Battery external body
30: laminated electrode body
31: Separator
32: heat resistant layer
40: laminated electrode body
41: Negative electrode
42: Heat resistant layer
43: separator
44: positive
51: a region where the first particles are melted
51a: junction point
52: Second particle
52a: isolation point
53: Binder
54: third particle
54a: isolation point

Claims (6)

A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte secondary battery comprising a negative electrode active material layer, a positive electrode active material layer, a separator, and a laminated electrode body in which the negative electrode active material layer or the heat resistant layer disposed between the positive electrode active material layer and the separator is laminated,
A laminated body in which a heat-resistant precursor layer including a first particle and a second particle having a melting point higher than that of the first particle is sandwiched by the active material layer and the separator is set to be higher than the melting point of the first particle, And thermally compressing the heat-resistant layer at a temperature lower than the melting point of the second particles and the melting point of the separator to thereby form the heat-resistant layer. The method of claim 1,
The heat-resistant precursor layer further comprises a third particle having a melting point higher than the melting point of the first particle and lower than the melting point of the second particle,
Wherein the thermal compression is performed at a temperature higher than the melting point of the first particles and lower than a melting point of the third particles and the separator. The method of claim 2,
Wherein the content of the first particles and the third particles is 7 to 30 mass% with respect to the total solid content of the heat resistant layer. 4. The method according to any one of claims 1 to 3,
Wherein the first particles have a melting point of 60 to 110 占 폚. A nonaqueous electrolyte secondary battery comprising a laminated electrode body in which a negative electrode active material layer, a positive electrode active material layer, a separator, and a heat resistant layer disposed between the negative electrode active material layer or the positive electrode active material layer and the separator,
Wherein the heat resistant layer comprises a first particle and a second particle having a melting point higher than that of the first particle,
Wherein the first particles are melted and the active material layer and the separator are bonded to each other. The method of claim 5,
Wherein the heat resistant layer further comprises third particles having a melting point higher than the melting point of the first particles and lower than a melting point of the second particles.

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