KR20130102498A - Secondary battery - Google Patents

Abstract

PURPOSE: A secondary battery is provided to suppress the separation of an active material from an active material layer and the crack of the cut of a separator or a current collector, thereby improving cycle durability. CONSTITUTION: A secondary battery (10) includes a positive electrode (140) including a positive active material layer (141); a negative electrode (150) including a negative active material layer; a separator arranged between the positive electrode and the negative electrode; an adhesive layer (170) which is arranged between the positive electrode and the separator and/or the negative electrode and the separator and attaches the positive electrode and/or negative electrode with the separator. The ratio of the contact area where the adhesive layer is in contact with the positive active material layer and/or negative active material layer is different from an area where the positive active material layer and the negative active material layer are overlapped, within a range that the positive active material layer and the negative active material layer are not overlapped with each other.

Description

Secondary Battery {SECONDARY BATTERY}

The present invention relates to a secondary battery.

BACKGROUND ART [0002] A secondary battery typified by a lithium ion secondary battery is attracting attention as a power source for driving a vehicle motor in terms of high voltage, high energy density, and high output.

The lithium ion secondary battery includes a positive electrode active material layer bonded to the positive electrode current collector, a negative electrode active material layer bonded to the negative electrode current collector, and a separator having opposing surfaces facing the surfaces of the respective active material layers. It is also known that, as a lithium ion secondary battery, the opposing face of the separator and the face of each active material layer are bonded by a resin adhesive layer (see, for example, Patent Document 1). Such a secondary battery has a structure in which a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, a resin adhesive layer, and a separator are laminated or wound. The adhesion of each active material to the separator is increased by the resin adhesive layer, so that short circuiting and resistance increase can be suppressed.

Japanese Patent Application Laid-Open No. 6-36801

However, it has been found that the cycle durability of the secondary battery may deteriorate depending on the state of the resin adhesive layer while the present inventors proceed to the examination of the secondary battery. More specifically, it has been found that when the resin adhesive layer is provided over the entire range of the overlapping area and the overlapping area as viewed from the thickness direction of the positive electrode active material layer and the negative electrode active material layer, the cycle durability may be deteriorated.

In the negative electrode active material layer and the positive electrode active material layer, the lithium ion is occluded or released in association with charge and discharge is a range in which the negative electrode active material layer and the positive electrode active material layer overlap each other when viewed from the thickness direction, Lt; / RTI > As a result, in the range where the negative electrode active material layer and the positive electrode active material layer overlap, volume change occurs with the charge and discharge in the electrode, while expansion and contraction do not occur in the electrode in the range where the negative electrode active material layer and the positive electrode active material layer do not overlap Do not. In the case where the resin adhesive layer is provided in the entire range and the active material layer is confined, stress concentration occurs in the members such as the separator and current collector near the boundaries of both ranges due to the gap of such volume change. Further, stress concentration to the vicinity of the boundary is promoted by repetition of the cycle test, cracking or cutting of the separator and the current collector or removal of the active material from the active material layer occurs, and as a result, the cycle durability may deteriorate.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is an object of the present invention to provide a secondary battery capable of improving cycle durability.

A secondary battery of the present invention for achieving the above object has a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, and a separator disposed between the positive electrode and the negative electrode. Further, the secondary battery of the present invention has at least one of a positive electrode and a separator, or a negative electrode and a separator, and has an adhesive layer for adhering at least one of the positive electrode and the negative electrode to the separator. In the secondary battery of the present invention, when viewed from the thickness direction of the active material layer, the adhesive layer is in contact with at least one of the positive electrode active material layer and the negative electrode active material layer in a range where the positive electrode active material layer and the negative electrode active material layer overlap each other, The ratio of the surface area to the surface area is different.

According to the secondary battery having the above-described configuration, the restraint of the separator is alleviated uniformly in both the range where the negative electrode active material layer and the positive electrode active material layer overlap each other and the range where the positive electrode active material layer does not overlap. As a result, the concentration of stress due to the gap of the volume change in both of the ranges due to charging and discharging is eliminated, and as a result, cracks or cutting of the current collector and the separator, or detachment of the active material from the active material layer, Durability can be improved.

1 is a perspective view showing a schematic structure of a secondary battery according to an embodiment.
Fig. 2 is a sectional view taken along the line 2-2 in Fig. 1. Fig.
3 is a plan view showing the active material layer, the adhesive layer and the separator from the thickness direction.
4 is a partially enlarged cross-sectional view of a main part of the secondary battery of the first embodiment.
5 is a partially enlarged sectional view showing a main part of a secondary battery of a comparative example.
Fig. 6 is a partially enlarged cross-sectional view of the main part of the secondary battery of the second embodiment. Fig.
7 is a partially enlarged cross-sectional view of the main part of the secondary battery of the third embodiment.
8 is a partially enlarged cross-sectional view of a main part of a modification of the third embodiment.
Fig. 9 is a partially enlarged cross-sectional view of the main part of the secondary battery of the fourth embodiment. Fig.
10 is a partially enlarged sectional view showing a main part of a modification of the fourth embodiment.
11 is a partially enlarged cross-sectional view of the main part of the secondary battery of the fifth embodiment.
12 is a partially enlarged cross-sectional view of the main part of the secondary battery of the sixth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and are different from actual ratios.

≪ First Embodiment >

1, the lithium ion secondary battery 10 (secondary battery) according to the first embodiment is sealed by a casing member 110 covering the substantially rectangular power generating element 100 in which charge / discharge reaction proceeds, Lt; / RTI > The lithium ion secondary battery 10 has a flat rectangular shape. The positive electrode current collecting plate 120 and the negative electrode collecting plate 130 for drawing electric power are drawn out from both sides of the lithium ion secondary battery 10. [

2, the power generating element 100 includes a positive electrode 140 formed on both surfaces of the positive electrode current collector 142 and a negative electrode active material layer 151 formed on both surfaces of the negative electrode current collector 152, And a negative electrode 150 formed on both sides of the negative electrode 150. The power generation element 100 also has a separator 160 disposed between the positive electrode 140 and the negative electrode 150 that constitutes the electrolyte layer by impregnation of the electrolyte. A plurality of positive electrodes 140 and a plurality of negative electrodes 150 are alternately stacked via a separator 160. The power generating element 100 includes an adhesive layer 170 disposed between the positive electrode 140 and the separator 160 to adhere them and an adhesive layer 180 disposed between the negative electrode 150 and the separator 160 to adhere them, Respectively.

The adjacent positive electrode active material layer 141, the electrolyte layer (separator 160) and the negative electrode active material layer 151 constitute one unit cell layer 190. The unit cell layers 190 are electrically connected in parallel by stacking a plurality of unit cells.

The negative electrode active material layers 151 are formed on only one side of the two negative electrode current collectors 154 disposed on the outermost layers on both sides in the stacking direction. The present invention is not limited to the embodiment shown in Fig. 2, but includes a configuration in which the arrangement of the positive electrode 140 and the negative electrode 150 is replaced in Fig. In this case, the positive electrode current collector 142 is disposed on both outermost layers in the stacking direction, and the positive electrode current collector 142 disposed on the outermost layer is formed with the positive electrode active material layer 141 on only one side. The negative electrode active material layer 151 and the positive electrode active material layer 142 are formed on both surfaces of the negative electrode collector 154 or the positive electrode collector 142 in both the positive electrode 140 and the negative electrode 150 when disposed on the outermost layer May be formed.

Each member will be described.

The casing member 110 is thermally fused to the periphery thereof to seal the power generation element 100 in a state in which the positive electrode current collector plate 120 and the negative electrode current collector plate 130 are led out. The casing member 110 is, for example, a laminate film having a laminated structure of aluminum and a resin material. As the laminate film, for example, a laminate film of a three-layer structure composed of a laminate of a polypropylene, an aluminum and a polyamide-based synthetic resin in this order can be used, but is not limited thereto.

The positive electrode current collector plate 120 is electrically connected to the positive electrode current collector 142 and is led to the outside of the casing member 110 so as to be fitted to one end of the casing member 110. The negative electrode collector plate 130 is electrically connected to the negative electrode collector 152 and is led to the outside of the casing member 110 so as to be fitted to the other end of the casing member 110.

A positive electrode lead 143 for electrically connecting the positive electrode collector plate 120 and the positive electrode collector 142 is provided on the positive electrode collector plate 120 by ultrasonic welding or resistance welding. The positive electrode collector plate 120 may be formed by extending the positive electrode collector 142. A negative electrode lead 153 for electrically connecting the negative electrode current collector plate 130 and the negative electrode current collector 152 is provided on the negative electrode current collector plate 130 by ultrasonic welding or resistance welding. The negative electrode current collector plate 130 may be formed by extending the negative electrode current collector 152.

The positive electrode current collector 142 is, for example, an aluminum foil. The negative electrode current collector 152 is, for example, a copper foil. The positive electrode current collector 142 and the negative electrode current collector 152 may be made of, for example, a stainless steel foil, a clad material of nickel and aluminum, a clad material of copper and aluminum, Or the like. The thickness of the positive electrode collector 142 and the thickness of the negative electrode collector 152 are, for example, about 1 to 100 mu m and preferably about 1 to 50 mu m, respectively.

The positive electrode active material layer 141 includes one or more kinds of positive electrode active materials capable of lithium intercalation and deintercalation, and may include a conductive auxiliary agent and a binder as necessary. The positive electrode active material is not particularly limited, and those generally used for a lithium ion secondary battery can be used. For example, a chalcogenide containing no lithium such as molybdenum sulfide (MoS ₂ ), niobium selenide (NbSe ₂ ), titanium sulphide (TiS ₂ ) or vanadium oxide (V ₂ O ₅ ) Containing compound or a polymer compound such as polyacetylene or polypyrrole. In particular, a lithium-containing compound is preferable from the viewpoint of high voltage and high energy density expected, and a composite oxide containing lithium and a transition metal element or a phosphate compound containing lithium and a transition metal element is more preferable. Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium-nickel-manganese composite oxide (LiNi _x Mn _{1 - x} O ₂ ), lithium-nickel-manganese-cobalt composite oxide (LiNi _x Mn _y Co _{1 -x- y} O ₂ ), lithium excess nickel-manganese-cobalt composite oxide (Li [Li _x Ni _y Mn _z Co _{1 -xyz} ] O ₂ ), and lithium manganese oxide having a spinel structure (LiMn ₂ O ₄ ). Specific examples of the phosphate compound containing lithium and a transition metal element include lithium iron phosphate (LiFePO ₄ ), lithium manganese phosphate (LiMnPO ₄ ), and lithium cobalt phosphate (LiCoPO ₄ ).

The thickness of the positive electrode active material layer 141 is not particularly limited, but is, for example, about 2 to 100 占 퐉. The maximum volume change rate of the charged state and the discharged state of the positive electrode active material layer 141 is, for example, 5% or more and 20% or less.

The negative electrode active material layer 151 includes one or more negative electrode active materials capable of reversibly intercalating and deintercalating lithium ions and may include a conductive auxiliary agent and a binder as required. The negative electrode active material includes, for example, a carbon material, a metal oxide, or a polymer compound. Examples of the carbon material include natural graphite, artificial graphite, cokes, and carbon black. Examples of the metal oxide include iron oxide, ruthenium oxide, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), and molybdenum oxide, and examples of the polymer compound include polyacetylene and polypyrrole.

As a negative electrode material capable of occluding and releasing lithium, a material containing at least one of a metal element and a semimetal element capable of forming an alloy with lithium is also included as a constituent element. The negative electrode material may be a single metal element or a semi-metallic element, an alloy, a compound, or a compound having at least one or more of these phases. In the present invention, the alloy includes not only two or more kinds of metal elements but also one or more kinds of metal elements and one or more kinds of semimetal elements. Moreover, you may contain the nonmetallic element. The structure may include a solid solution, a process (eutectic mixture), an intermetallic compound, or two or more of them.

Examples of the metal element or the semimetal element include tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Zn), antimony (Sb), bismuth There can be mentioned gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr) or yttrium (Y). Among them, a Group 14 metal element or semi-metal element in the long period type periodic table is preferable, and silicon or tin is particularly preferable. This is because silicon and tin have a high capacity to absorb and discharge lithium, and thus a high energy density can be obtained.

Examples of the tin alloy include silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium (Ti), germanium, bismuth, antimony, and chromium (Cr) as second constituent elements other than tin, And at least one kind selected from the group consisting of Examples of the silicon alloy include at least one of the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium as a second constituent element other than silicon Including species.

The compound of tin or the compound of silicon includes, for example, oxygen (O) or carbon (C), and may contain the above-mentioned second constituent element in addition to tin or silicon.

The thickness of the negative electrode active material layer 151 is not particularly limited, but is, for example, about 2 to 100 占 퐉. The maximum volume change rate of the charged state and the discharged state of the negative electrode active material layer 151 is, for example, 10% or more and 400% or less.

The separator 160 is interposed between the positive electrode active material layer 141 and the negative electrode active material layer 151 and has a role of preventing short-circuit caused by contact of the positive electrode active material and securing the electrolyte to ensure ion permeability. The separator 160 is formed of, for example, porous polyethylene (PE) having air permeability. However, the present invention is not limited to this, and known separator 160 used in general lithium ion secondary batteries can be applied. For example, as the separator 160, another polyolefin such as PP (polypropylene), a laminate having a three-layer structure of PP / PE / PP, polyamide, polyimide, aramid and nonwoven fabric may be used. Nonwoven fabrics are, for example, cotton, rayon, acetate, nylon, polyester.

Examples of the solvent for the electrolytic solution include lactone solvents such as? -Butyrolactone,? -Valerolactone,? -Valerolactone and? -Caprolactone, and organic solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, Carbonic acid ester solvents such as ethyl acetate or diethyl carbonate, ethers such as 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, tetrahydrofuran or 2-methyltetrahydro Ether solvents such as tetrahydrofuran and furane, nitrile solvents such as acetonitrile, non-aqueous solvents such as sulfolane solvents, phosphoric acids, phosphoric acid ester solvents and pyrrolidones. Any one solvent may be used alone, or two or more solvents may be mixed and used.

The lithium salt of the electrolytic solution may be any one as long as it dissolves in a solvent to generate ions, and either one of them may be used alone, or two or more kinds may be used in combination. (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium perchlorate (LiClO ₄ ), lithium trifluoromethanesulfonate (LiCF ₃ ), and the like can be used as long as the lithium salt is a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate SO _3), (methanesulfonyl trifluoromethanesulfonyl) imide lithium (LiN (SO ₂ CF ₃₎ bis _2), tris (methanesulfonyl trifluoromethyl) methyl lithium (LiC (SO ₂ CF _{3) 3),} titanium tetrachloride Lithium aluminate (LiAlCl ₄ ) or lithium hexafluorosilicate (LiSiF ₆ ). Among them, lithium hexafluorophosphate or lithium tetrafluoroborate is preferable from the standpoint of oxidation stability.

The concentration of the lithium salt in the electrolytic solution is preferably 0.1 mol or more and 3.0 mol or less, more preferably 0.5 mol or more and 2.0 mol or less based on 1 liter of the solvent. This is because good ion conductivity can be obtained within this range.

The electrolyte may be a polymer electrolyte or gel electrolyte, not an electrolytic solution.

The host polymer of the polymer or gel electrolyte is, for example, PVDF-HFP (a copolymer of polyvinylidene fluoride and hexafluoropropylene) containing 10% of HFP (hexafluoropropylene) copolymer. However, it is not particularly limited to this, and known electrolytes which are used in general lithium ion secondary batteries as host polymers of electrolytes can be applied. For example, it is also possible to apply a polymer having no other lithium ion conductivity or a polymer having an ion conductivity (a solid polymer electrolyte). The other polymer having no lithium ion conductivity is, for example, PAN (polyacrylonitrile) or PMMA (polymethyl methacrylate). The polymer having ionic conductivity is, for example, PEO (polyethylene oxide) or PPO (polypropylene oxide).

The thickness of the separator 160 is not particularly limited, and conventionally known knowledge about the battery can be suitably referred to. The thickness of the separator 160 is preferably 1 to 50 占 퐉, more preferably 2 to 30 占 퐉, and still more preferably 5 to 25 占 퐉.

3, the flat area (area of the surface intersecting in the thickness direction) of the negative electrode active material layer 151 is larger than the flat area of the positive electrode active material layer 141, as shown from the thickness direction of each member. The flat area of the separator 160 is larger than the flat area of the negative electrode active material layer 151 and the flat area of the positive electrode active material layer 141. However, in the case of a negative electrode active material layer containing a negative electrode material having a large lithium potential of 1 V or more, the flat area of the negative electrode active material layer 151 may be smaller than the flat area of the positive electrode active material layer 141.

3 and 4, the adhesive layer 170 has a flat area equal to the flat area of the positive electrode active material layer 141. As shown in Fig. The adhesive layer 170 is formed on the positive electrode active material layer 141 in the entire range of the range in which the positive electrode active material layer 141 and the negative electrode active material layer 151 are overlapped with each other Contact.

On the other hand, the flat area of the adhesive layer 180 is larger than the flat area of the positive electrode active material layer 141 and smaller than the flat area of the negative electrode active material layer 151. The adhesive layer 180 not only contacts the negative electrode active material layer 151 within a range in which the active material layers overlap but also has a range in which the positive electrode active material layer 141 and the negative electrode active material layer 151 do not overlap in the thickness direction The negative electrode active material layer 151 is in contact with the negative electrode active material layer 151).

The ratio of the area in which the adhesive layer 180 contacts the negative electrode active material layer 151 differs in the range where the active material layers overlap and the range in which the active material layers do not overlap. The adhesive layer 180 is in contact with the negative electrode active material layer 151 in the entire range in which the active material layers overlap. On the other hand, in the range where the active material layers do not overlap, the adhesive layer 180 is in contact with only a part of the negative electrode active material layer 151. Therefore, in the range where the active material layers do not overlap, the ratio of the area in which the adhesive layer 180 contacts the negative electrode active material layer 151 is smaller than the range in which the active material layers overlap.

The thickness of the adhesive layer 170 and the thickness of the adhesive layer 180 are not particularly limited, but are preferably 0.1 to 20 占 퐉. More preferably from 0.5 to 15 占 퐉, and still more preferably from 0.5 to 10 占 퐉.

Examples of the main constituent material of the adhesive layer 170 and the adhesive layer 180 include olefin resins such as polyethylene (PE) and polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) (PEN), polyacrylonitrile (PAN), polyimide (PI), polyamide (PA), polyamideimide (PAI), cellulose, carboxymethylcellulose (CMC), ethylene- 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- Block copolymers and hydrogenated products thereof, polyvinylidene fluoride (PVdF), polyvinylidene fluoride (having a carboxyl group on some side chains), polyvinylidene fluoride-hexafluoropropylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), ethylene / hexafluoropropylene copolymer Fluorine resins such as tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene chlorotrifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF), vinylidene fluoride- (VDF-HFP fluorine rubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoro (VDF-PFP-based fluorine rubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluorine rubber (VDF-PFP-TFE based fluorine rubber), vinylidene fluoride-perfluoro Vinylidene fluoride-based rubber such as methylvinylether-tetrafluoroethylenic fluororubber (VDF-PFMVE-TFE fluororubber) and vinylidene fluoride-chlorotrifluoroethylene fluororubber (VDF-CTFE fluororubber) (Meth) acrylic resins such as polymethyl acrylate (PMA) and polymethyl methacrylate (PMMA), aramid, and polyvinylidene chloride (PVDC). Among these, polyvinylidene fluoride, polyimide, styrene-butadiene rubber, carboxymethylcellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile and polyamide are more preferable. The materials used for these suitable adhesive layers 170 and 180 are excellent in heat resistance and stable both in oxidation potential and in reduction potential. The materials used for these adhesive layers 170 and 180 may be used alone or in combination of two or more. However, it goes without saying that the materials used for the adhesive layers 170 and 180 are not limited to these. Among them, for example, polyvinylidene fluoride (PVdF), (meth) acrylic resin, olefin resin and the like can be applied to both of the oxidizing side and the reducing side. In addition, SBR or the like is preferably used on the negative electrode side in view of the strong resistance to the reduction potential. PTFE or the like is preferably used on the positive electrode side in view of its strong resistance to oxidation potential.

The manufacturing method of the lithium ion secondary battery 10 of the present embodiment is not particularly limited, and it can be manufactured by applying conventionally known methods. An example of this will be described below.

First, the positive electrode 140 and the negative electrode 150 are prepared.

In the production of the negative electrode (150), a slurry for a negative electrode active material layer containing a negative electrode active material is prepared and applied to one surface of the negative electrode collector (152). The slurry for the negative electrode active material layer is prepared by dispersing a mixture including a negative electrode active material, a conductive auxiliary agent and a binder in a solvent.

The conductive auxiliary agent refers to an additive compounded to improve conductivity. The conductive auxiliary agent that can be used in the present embodiment is not particularly limited, and conventionally known knowledge can be appropriately referred to. For example, carbon materials, such as carbon black, such as acetylene black, graphite, and carbon fiber, are mentioned. When the active material layer contains the conductive auxiliary agent, the electronic network inside the active material layer is effectively formed, and the input / output characteristics of the battery can be improved. Further, in this embodiment, the carbon material used as the negative electrode active material may have conductivity itself. In this case, the use of the conductive auxiliary agent is not necessarily required.

The binder used for the slurry for the negative electrode active material layer is added for the purpose of maintaining the electrode structure (three-dimensional network) by binding the active materials or binding the active material with the current collector or the conductive auxiliary agent. The binder contained in the slurry for the negative electrode active material layer is not particularly limited, and examples thereof include the following materials. Thickening agents such as cellulose and carboxymethylcellulose (CMC); Polyolefins such as polyethylene, polypropylene, polyethylene terephthalate (PET), polyether nitrile, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyvinyl chloride, styrene-butadiene rubber (SBR) Thermoplastic resins such as isoprene rubber, 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; (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene (ethylene terephthalate) Fluorine resins such as tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF); Hexafluoropropylene fluorine rubber (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-hexafluoropropylene fluorine rubber (VDF-HFP fluorine rubber), vinylidene fluoride- (VDF-PFP-based fluorine rubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluorine rubber (VDF-PFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFMVE-TFE fluororubber), vinylidene fluoride-chlorotrifluoroethylene fluororubber (VDF-CTFE fluororubber), etc., fluoride-fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluororubber Vinylidene fluoride-based fluorine rubber; Acrylic resin; Polyurethane resin; And urea resins. These may be used alone or in combination of two or more.

The solvent used in 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, . When an aqueous solvent such as water is used, for example, carboxymethyl cellulose (CMC) or the like may be added. The amount of the solvent is not particularly limited, but is preferably 1 to 90 mass%, more preferably 5 to 80 mass%, and still more preferably 10 to 75 mass%, based on the total mass of the slurry.

The slurry for the negative electrode active material layer is applied to the negative electrode collector 152 by conventionally known means such as a die coater, a knife coater, a lip coater, a gravure coater, a dip coater, a comma coater, a spin coater, a dispenser or a bar coater.

Subsequently, the coating film of the slurry for the negative electrode active material layer formed on one surface of the negative electrode collector 152 is dried. Thereby, the solvent in the coating film is removed. The drying means for drying the coating film is also not particularly limited, and conventionally known knowledge regarding electrode production can be appropriately referred to. The drying conditions (drying time, drying temperature, drying method, etc.) can be appropriately set in accordance with the application amount of the slurry or the volatilization rate of the solvent. The negative electrode active material layer 151 is similarly formed on the other surface of the negative electrode collector 152. Thereafter, the obtained dried product is pressed, whereby the density, porosity and thickness of the electrode are adjusted.

The positive electrode 140 is also formed in the same manner as the preparation of the negative electrode 150. After the slurry for the positive electrode active material layer to be the positive electrode active material layer 141 is produced, the positive electrode 140 is coated on the surface of the positive electrode collector 142, The slurry for the positive electrode active material layer is prepared by dispersing the positive electrode active material, the conductive auxiliary agent and the binder in a solvent.

After the negative electrode 150 and the positive electrode 140 are prepared, a slurry (hereinafter, simply referred to as an adhesive layer slurry) for forming the adhesive layer 170 and the adhesive layer 180 is formed on the positive electrode active material layer 141, the negative electrode active material layer 151 ) Or the separator 160, as shown in Fig.

The slurry for the adhesive layer is prepared by dispersing a mixture containing the constituent materials of the adhesive layers 170 and 180 in the above-described examples in a solvent. As the solvent used for the adhesive layer slurry, for example, N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide, methanol, ethanol, isopropanol and water may be used. Further, if the material is able to withstand the environment of the battery without storing and releasing lithium, it may be included in the adhesive layer 170 or 180. [

The slurry for the adhesive layer is applied to the positive electrode active material layer 141 and the negative electrode active material layer 151 by conventionally known means such as a die coater, a knife coater, a lip coater, a gravure coater, a dip coater, a comma coater, a spin coater, a dispenser, Or the separator 160, as shown in Fig.

The slurry for the adhesive layer is formed on the entire surface of the surface of the positive electrode active material layer 141 opposite to the surface contacting the positive electrode current collector 142 or on the entire surface of the separator 160 in contact with the positive electrode active material layer 141 And the adhesive layer 170 is formed. On the other hand, with respect to the negative electrode active material layer 151, the slurry for the adhesive layer is not applied to the entire surface of the negative electrode active material layer 151 opposite to the surface in contact with the negative electrode collector 152, And the adhesive layer 180 is formed by drying. Alternatively, the adhesive layer slurry is intermittently applied and dried to the separator 160, and the adhesive layer 180 is formed.

For example, a slurry for an adhesive layer is applied and dried in a state where a masking tape is adhered to a peripheral portion of the negative electrode active material layer 151 with a predetermined width, whereby a portion where the negative electrode active material layer 151 free of the adhesive layer 180 is exposed May be formed on the peripheral portion of the negative electrode active material layer 151.

The positive electrode 140, the negative electrode 150 and the separator 160 are laminated to form an adhesive layer 170 between the positive electrode 140 and the separator 160 and an adhesive layer 180 between the negative electrode 150 and the separator 160. [ . The positive electrode 140, the negative electrode 150, and the separator 160 are stacked until a desired number of stacked layers are formed, and then a pressure is applied from the stacking direction while being heated by a hot press. By this operation, the stacked body is integrated with the adhesive layers 170 and 180 interposed therebetween.

Subsequently, the laminate is vacuum-dried, and then is surrounded by the casing member 110. Then, the electrolyte of the electrolyte solution and the sealing member 110 are sealed to produce the lithium ion secondary battery 10.

The lithium ion secondary battery 10 is particularly suitable as a battery mounted on a vehicle as a power source for driving a motor. Here, the vehicle includes, for example, a vehicle that drives a wheel by a motor and another vehicle (e.g., a train). Examples of the above automobiles include electric vehicles, hybrid automobiles such as series hybrid cars and parallel hybrid automobiles, and the like. Further, it may be provided as a combined battery in which a plurality of batteries themselves are combined. Of course, it is natural that it can be mounted on a vehicle when it is made of a battery.

The operation and effect of this embodiment will be described.

5, the adhesive layer 180A for adhering the negative electrode active material layer 151 and the separator 160 is formed in a range in which the active material layers overlap and a range in which the active material layers do not overlap The negative electrode active material layer 151 is constrained to the separator 160 in its entire range. As a result, when a gap of volume change occurs due to the difference in the progress of the reaction between the range where the active material layers overlap and the range where the active material layers do not overlap at the time of charging and discharging, Concentration occurs. Further, stress concentration to the vicinity of the boundary is promoted by repetition of the cycle test, so that cracks or breakage of the negative electrode current collector 152 and the separator 160, or separation of the active material from the negative electrode active material layer 151 occurs, As a result, the cycle durability may deteriorate.

On the other hand, in the lithium ion secondary battery 10 of the present embodiment, the adhesive layer 180 does not contact the negative electrode active material layer 151 in the range where the active material layers overlap and the active material layer does not overlap, The ratio of the contact area of the adhesive layer 180 to the adhesive layer 151 is different in both ranges. With this configuration of the adhesive layer 180, the restraint of the separator 160 is alleviated uniformly in both the range where the active material layers overlap and the range where the active material layers do not overlap. As a result, the negative electrode current collector 152 and the separator 160 are cracked or cut, or the negative active material layer 151 , The cycle durability can be improved.

The maximum volume change rate of the charged state and the discharged state of the positive electrode active material layer 141 and the negative electrode active material layer 151 was 10% or more because the restraint of the separator 160 was uniformly suppressed by the adhesive layer 180 The stress concentration due to the gap of the volume change within the range where the active material layers overlap and the range where the active material layers do not overlap with each other is eliminated. As a result, cracking or cutting of the negative electrode current collector 152 and the separator 160, or detachment of the active material from the negative electrode active material layer 151 is suppressed, so that cycle durability can be improved.

≪ Second Embodiment >

6, the configuration of the adhesive layer 280 contacting the negative electrode active material layer 151 in the lithium ion secondary cell 20 of the second embodiment is different from that of the first embodiment. Regarding other structures and manufacturing methods, since the lithium ion secondary battery 20 is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and redundant explanations are omitted.

The ratio of the area in which the adhesive layer 280 contacts the negative electrode active material layer 151 differs from the range in which the active material layers overlap and the range in which the active material layers do not overlap as in the first embodiment. However, in the present embodiment, the adhesive layer 280 is in contact with only the part of the negative electrode active material layer 151 in a range where the active material layer is in contact with the negative electrode active material layer 151 in the entire range in which the active material layers do not overlap, Which is different from the first embodiment.

The adhesive layer 280 is formed by laminating an adhesive layer slurry on the periphery of the negative electrode active material layer 151 exposed with a predetermined width in a state where a masking tape is attached to a portion other than the peripheral portion of the negative electrode active material layer 151 And is disposed on the peripheral portion of the negative electrode active material layer 151 by being coated.

The adhesive layer 280 does not contact the negative electrode active material layer 151 and the adhesive layer 280 does not contact the negative electrode active material layer 151 in the entire range where the active material layers overlap and the active material layers do not overlap. The ratio of the contact area is different in both ranges thereof. This configuration of the adhesive layer 280 alleviates the restraint of the separator 160 uniformly in both the range where the active material layers overlap and the range where the active material layers do not overlap. As a result, the negative electrode current collector 152 and the separator 160 are cracked or cut, or the negative active material layer 151 , The cycle durability can be improved.

Even if the maximum volume change rate of the charged state and the discharged state of the positive electrode active material layer 141 and the negative electrode active material layer 151 is 5% or more because the restraint of the separator 160 is uniformly suppressed by the adhesive layer 280 , The stress concentration due to the gap between the volume change in the range where the active material layers overlap and the range in which the active material layers do not overlap is eliminated. As a result, cracking or cutting of the negative electrode current collector 152 and the separator 160, or detachment of the active material from the negative electrode active material layer 151 is suppressed, so that cycle durability can be improved.

≪ Third Embodiment >

7, in the lithium ion secondary cell 30 of the third embodiment, the structure of the adhesive layer 380 contacting the negative electrode active material layer 151 is different from that of the first embodiment. Regarding other structures and manufacturing methods, the lithium ion secondary battery 30 is the same as that of the first embodiment, and hence the same constituent elements are denoted by the same reference numerals, and redundant explanations are omitted.

The ratio of the area in which the adhesive layer 380 contacts the negative electrode active material layer 151 differs from the range in which the active material layers overlap and the range in which the active material layers do not overlap as in the first embodiment. However, the present embodiment is different from the first embodiment in that the adhesive layer 380 contacts the negative electrode active material layer 151 only in a range where the active material layers overlap. The adhesive layer 380 is in contact with the negative electrode active material layer 151 in the entire range of overlapping of the active material layers and does not contact the negative electrode active material layer 151 in a range where the active material layers do not overlap.

The adhesive layer 380 can be formed by applying the adhesive layer slurry to the negative electrode active material layer 151 in a state in which the masking tape is adhered to the peripheral portion of the negative electrode active material layer 151 with a predetermined width, And is disposed in contact with the active material layer 151.

Alternatively, the adhesive layer 380 may be formed to have a flat area and a flat shape such as a flat area and a flat shape (a shape of a surface intersecting in the thickness direction) of the positive electrode active material layer 141, (151) so as to be in contact with the negative electrode active material layer (151) only in a range where the active material overlaps.

Alternatively, the slurry for the adhesive layer is applied to the entire surfaces of both surfaces of the separator 160, and in the hot pressing, as shown in Fig. 8, the press surface P1 which presses from the stacking direction only covers a range in which the active material layers overlap Pressure. In this case, the adhesive layer 380A is formed only in a range where the active material layers overlap. On the other hand, in the range where the active material layers do not overlap, the applied slurry for the adhesive layer is not pressed, and as a result, the non-adhesive layer 380B having a weaker adhesive force than the adhesive layer 380A is formed.

The adhesive layer 380 does not contact the negative electrode active material layer 151 and the adhesive layer 380 does not contact the negative electrode active material layer 151 in the entire range where the active material layers overlap and the active material layers do not overlap. The ratio of the contact area is different in both ranges thereof. This configuration of the adhesive layer 380 relaxes the restraint of the separator 160 uniformly in both the range where the active material layers overlap and the range where the active material layers do not overlap. As a result, the negative electrode current collector 152 and the separator 160 are cracked or cut off, or the negative electrode active material layer 151 , The cycle durability can be improved.

Even if the maximum volume change rate of the charged state and the discharged state of the positive electrode active material layer 141 and the negative electrode active material layer 151 is 10% or more because the restraint of the separator 160 is uniformly suppressed by the adhesive layer 380 , The stress concentration due to the gap between the volume change in the range where the active material layers overlap and the range in which the active material layers do not overlap is eliminated. As a result, cracking or cutting of the negative electrode current collector 152 and the separator 160 or removal of the active material from the negative electrode active material layer 151 is suppressed, so that cycle durability can be improved.

Particularly, in this embodiment, since the adhesive layer 380 is in contact with the negative electrode active material layer 151 only in the range where the active material layers overlap, the restraint by the separator 160 in the range where the active material layers do not overlap with each other is completely eliminated do. Therefore, the stress due to the volume change of the negative-electrode active material layer 151 accompanying the charging and discharging is averaged and dispersed in the entire overlapping range of the active material layers, and as a result, the cycle durability can be further improved.

≪ Fourth Embodiment &

9, the configuration of the adhesive layer 480 contacting the negative electrode active material layer 151 in the lithium ion secondary battery 40 of the fourth embodiment is different from that of the first embodiment. Regarding other structures and manufacturing methods, the lithium ion secondary battery 40 is the same as that of the first embodiment, and thus the same constituent elements are denoted by the same reference numerals, and redundant explanations are omitted.

The ratio of the area in which the adhesive layer 480 contacts the negative electrode active material layer 151 differs from the range in which the active material layers overlap and the range in which the active material layers do not overlap as in the first embodiment. However, the present embodiment is different from the first embodiment in that the adhesive layer 480 contacts the negative electrode active material layer 151 only when the active material layers do not overlap. The adhesive layer 480 is in contact with the negative electrode active material layer 151 over the entire range in which the active material layers do not overlap and does not contact the negative electrode active material layer 151 in the range where the active material layers overlap.

The adhesive layer 480 preferably prevents permeation of ions. For example, the ratio of the voids (void ratio) present in the adhesive layer 480 is controlled to a predetermined range, so that the inflow of the electrolyte solution into the adhesive layer 480 is prevented. The porosity is measured, for example, by using mercury porosimetry for the adhesive layer 480 that has been dried after the electrolyte is washed away. The porosity of the adhesive layer 480 is preferably 0% or more and 10% or less.

The adhesive layer 480 is formed by laminating an adhesive layer slurry on the peripheral portion of the negative electrode active material layer 151 exposed with a predetermined width in a state where a masking tape is attached to a portion other than the peripheral portion of the negative electrode active material layer 151 The negative electrode active material layer 151 is disposed so as to contact the negative electrode active material layer 151 only in a range where the active material does not overlap.

Alternatively, the adhesive layer slurry may be applied to the entire surface of both surfaces of the separator 160, and, during hot pressing, the press surface P2 to be pressed from the stacking direction as shown in Fig. Only the range may be pressurized. In this case, the adhesive layers 480A and 170A are formed only in the range where the active material layers do not overlap. On the other hand, in the range where the active material layers overlap, the applied adhesive layer slurry is not pressed, and as a result, the non-adhesive layers 480B and 170B having weaker adhesive force than the adhesive layers 480A and 170A are formed.

The adhesive layer 480 does not contact the negative electrode active material layer 151 and the adhesive layer 480 does not contact the negative electrode active material layer 151 in the entire range where the active material layers overlap and the active material layers do not overlap. The ratio of the contact area is different in both ranges. This configuration of the adhesive layer 480 alleviates the restraint of the separator 160 uniformly in both the range where the active material layers overlap and the range where the active material layers do not overlap. As a result, the negative electrode current collector 152 and the separator 160 are cracked or cut off, or the negative electrode active material layer 151 , The cycle durability can be improved.

Since the restraint of the separator 160 is uniformly suppressed by the adhesive layer 480, the maximum volume change rate of the charged state and the discharged state of the positive electrode active material layer 141 and the negative electrode active material layer 151 is 5% or more The stress concentration due to the gap of the volume change within the range where the active material layers overlap and the range where the active material layers do not overlap with each other is eliminated. As a result, cracking or cutting of the negative electrode current collector 152 and the separator 160, or detachment of the active material from the negative electrode active material layer 151 is suppressed, so that cycle durability can be improved.

Particularly, in the present embodiment, since the adhesive layer 480 contacts the negative electrode active material layer 151 only in a range where the active material layers do not overlap, the restraint by the separator 160 in a range where the active material layers do not overlap with the range Completely resolved. Therefore, the stress due to the volume change of the negative-electrode active material layer 151 accompanying the charging and discharging is averaged and dispersed in the entire overlapping range of the active material layers, and as a result, the cycle durability can be further improved.

When the permeation of ions is prevented by the adhesive layer 480, the electrolyte does not directly contact the negative electrode active material layer 151 within the range where the active material layers do not overlap. As a result, the solid electrolyte interface (SEI) The consumption of the electrolytic solution due to the formation of the electrolyte layer is suppressed, so that the cycle durability can be further improved.

≪ Embodiment 5 >

11, the lithium ion secondary battery 50 of the fifth embodiment is substantially the same as that of the third embodiment, except that the adhesive layer 580 contacting the negative electrode active material layer 151 is in a range where the active material layers overlap And the active material layer are disposed in such a manner as not to overlap the boundary line in the range where the active material layer does not overlap with the third embodiment. Regarding other structures and manufacturing methods, the lithium ion secondary battery 50 is the same as that of the third embodiment, and hence the same components are denoted by the same reference numerals, and redundant description is omitted.

The adhesive layer 580 is in contact with the negative electrode active material layer 151 only in a region where the active material layers overlap and the flat area of the adhesive layer 580 is smaller than the flat area of the adhesive layer 380 of the third embodiment. For example, by applying the adhesive layer slurry to the negative electrode active material layer 151 with the masking tape having a wider width than that of the third embodiment attached to the peripheral portion of the negative electrode active material layer 151, It is possible to dispose the adhesive layer 580 in a range where the active material overlaps the boundary line of the range where the layers do not overlap.

Alternatively, the slurry for the adhesive layer may be intermittently applied to the negative electrode active material layer 151 so as to have a flat area smaller than the flat area of the positive electrode active material layer 141 and a flat shape having a smaller outer shape than the flat shape of the positive electrode active material layer 141 The adhesive layer 580 can be disposed in a range in which the active materials are overlapped with each other avoiding the overlapping range of the active material layers and the boundary line of the range where the active material layers do not overlap.

In this embodiment, since the adhesive layer 580 is formed so as to avoid the overlapping range of the active material layers and the boundary line of the range where the active material layers do not overlap, the active material layers overlap each other due to the flat area and the tolerance of the position of the adhesive layer 580 It is difficult for the adhesive layer 580 to be pushed out from the boundary line in the range where the active material layer does not overlap. Therefore, the lithium ion secondary battery 50 has the effect of improving the yield in addition to the effect of the third embodiment.

≪ Sixth Embodiment &

12, the lithium ion secondary battery 60 of the sixth embodiment is substantially the same as that of the fourth embodiment except that the adhesive layer 680 in contact with the negative electrode active material layer 151 is formed in such a manner that the active material layers overlap each other And the active material layers are arranged so as not to overlap the boundary line in the range where the active material layers do not overlap with each other. Regarding other structures and manufacturing methods, the lithium ion secondary battery 60 is the same as that of the fourth embodiment, and thus the same constituent elements are denoted by the same reference numerals, and redundant explanations are omitted.

The adhesive layer 680 is in contact with the negative electrode active material layer 151 only within a range where the active material layers do not overlap and the flat area of the adhesive layer 680 is smaller than the flat area of the adhesive layer 480 of the fourth embodiment. For example, a masking tape is attached to a portion other than the peripheral portion of the negative-electrode active material layer 151, and the slurry for the adhesive layer is applied to the peripheral portion of the negative-electrode active material layer 151 exposed in a narrower width than in the fourth embodiment, It is possible to dispose the adhesive layer 680 within a range in which the active material does not overlap by avoiding the overlapping range of the active material layers and the boundary line of the range where the active material layers do not overlap.

In this embodiment, the adhesive layer 680 is formed so as not to overlap the range in which the active material layers overlap and the boundary line in which the active material layers do not overlap. Therefore, due to the tolerance of the flat area and position of the adhesive layer 680, It is difficult for the adhesive layer 680 to be pushed out from the boundary line in the range where the active material layers do not overlap. Therefore, the lithium ion secondary battery 60 has the effect of improving the yield in addition to the effect of the fourth embodiment.

Next, an embodiment of a secondary battery actually manufactured by the present inventors will be described.

≪ Example 1 >

(1) exterior

The present inventors prepared a laminate film in which the outermost layer was a PET film for surface protection, the Al film was a metal film layer, and the polypropylene film was a heat-sealable insulation film layer.

(2) Terminal leads

The present inventors used an Al plate for the positive electrode terminal lead and an Ni plate for the negative electrode terminal lead.

(3) separator

Further, the present inventors prepared a separator having a thickness of 24 占 퐉 made of polypropylene. In addition, the present inventors prepared an electrolyte solution in which LiPF ₆ electrolyte and vinylene carbonate (VC) were dissolved in a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC).

(4) Positive and negative electrodes

The present inventors mixing _{LiNi 1/3 Mn 1/3} Co 1/3 O 2 to 94% by mass, 3% by mass of acetylene black as a conductive auxiliary agent, 3% by weight of polyvinylidene fluoride (PVdF) as a binder, a positive electrode active material . Then, the present inventors added NMP as a slurry viscosity adjusting solvent until the viscosity became optimum in the coating process, thereby preparing a positive electrode active material slurry. The present inventors coated the positive electrode active material slurry on both sides of an aluminum foil having a thickness of 20 mu m which is a collector for positive electrode, dried and rolled to form a positive electrode having a positive electrode active material layer with a thickness of 40 mu m.

The present inventors mixed 90% by mass of natural graphite as a negative electrode active material, 2% by mass of carbon black as a conductive auxiliary agent, and 8% by mass of PVdF as a binder. Then, the present inventors added NMP as a slurry viscosity adjusting solvent until the viscosity became optimum in the coating process, thereby preparing a negative electrode active material slurry. The present inventors coated the negative electrode active material slurry on both sides of a copper foil having a thickness of about 10 mu m which is a current collector for negative electrode, dried and rolled to form a negative electrode having a negative electrode active material layer with a thickness of 50 mu m. When Li ₄ Ti ₅ O ₁₂ is used for the negative electrode material, the flat area of the positive electrode active material layer may be larger than the flat area of the negative electrode active material layer.

(5) Resin Adhesive Layer

The present inventors prepared a solvent by dispersing styrene-butadiene rubber and carboxymethylcellulose in water as a material for bonding the positive electrode active material layer and the separator, and coated the surface of the positive electrode active material layer with a dispenser.

In addition, the present inventors produced a solvent by dispersing styrene-butadiene rubber and carboxymethylcellulose in water as a material for bonding the negative electrode active material layer and the separator. The present inventors applied the surface of the negative electrode active material layer on which the masking tape was adhered to the place where the active material layers were not overlapped and the area where the active material layers were overlapped by 1 mm, using a dispenser. The masking tape was then removed.

(6) Assembly

The present inventors stored the positive electrode and the negative electrode in a laminate film which is a laminate of the negative electrode and the positive electrode, respectively, with the separator interposed therebetween. Then, the inventors of the present invention welded the negative electrode terminal leads made of Al and the negative electrode terminal leads made of Al, respectively, while the positive electrode collector and the negative electrode collector were protruded from the facing surface from the separator. Next, the present inventors protruded the positive electrode terminal lead and the negative electrode terminal lead from the opposite sides of the battery, respectively, and sandwiched in the external laminate film, and the three sides of the periphery were heat-welded. The present inventors sealed the whole by injecting LiPF ₆ electrolyte and vinylene carbonate (VC) as an electrolytic solution in a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC). Then, the present inventors made the active material layer and the separator to be thermally fused by a hot press (80 DEG C, 10 minutes) via the resin adhesive layer. Subsequently, initial charging and aging were carried out to produce a lithium ion secondary battery.

(7) Evaluation of cycle durability

The inventors of the present invention repeated the charging and discharging cycles of the constant current constant voltage charging and the constant current discharging at a charging current of 4.2 V, a discharging voltage of 2.75 V and a temperature of 55 ° C at a current value of 1C. The capacity retention after 200 cycles was 92%. Thereafter, some of the batteries were disassembled, but no abnormality such as separation of the active material from the positive electrode / negative electrode active material layer, breakage of the separator, breakage of the current collector, and crack was confirmed.

<Example 2>

(1) exterior

The procedure of Example 1 was repeated.

(2) Terminal leads

The procedure of Example 1 was repeated.

(3) separator

The procedure of Example 1 was repeated.

(4) Positive and negative electrodes

The procedure of Example 1 was repeated.

(5) Resin Adhesive Layer

The present inventors prepared a solvent by dispersing styrene-butadiene rubber and carboxymethylcellulose in water as a material for bonding the positive electrode active material layer and the separator, and coated the surface of the positive electrode active material layer with a dispenser.

The present inventors produced a solvent by dispersing styrene-butadiene rubber and carboxymethylcellulose as a material for adhering the negative electrode active material layer and the separator in water. The present inventors applied the surface of the negative electrode active material layer on which the masking tape was adhered to the portion where the active material layers overlapped and the area where the active material layers did not overlap by 0.5 mm, using a dispenser. Thereafter, the masking tape was removed.

(6) Assembly

The procedure of Example 1 was repeated.

(7) The present inventors repeatedly performed the charging / discharging cycles of the constant current constant voltage charging and the constant current discharging at a charging current of 4.2 V, a discharging voltage of 2.75 V, and a temperature of 55 캜 at a current value of 1C. The capacity retention after 200 cycles was 90%. Thereafter, some of the batteries were disassembled, but no abnormality such as separation of the active material from the positive electrode / negative electrode active material layer, breakage of the separator, breakage of the current collector, and crack was confirmed.

The present invention is not limited to the above-described embodiments, but may be modified in various ways within the scope of the claims.

For example, the take-out positions of the negative electrode current collecting plate and the positive electrode current collecting plate are not limited to the opposite positions as shown in Fig. The negative electrode current collecting plate and the positive electrode collecting plate may be separated from each other and drawn out from each side.

In the above-described embodiment, the flat area of the negative electrode active material layer is larger than the flat area of the positive electrode active material layer, but is not limited thereto. For example, when the negative electrode active material is lithium titanate: Li ₄ Ti ₅ O ₁₂ , the positive electrode active material layer is formed such that its flat area is larger than the flat area of the negative electrode active material layer. In this case, the ratio of the area in which the adhesive layer contacts the positive electrode active material layer differs within a range in which the active material layers overlap with the active material layer.

In the above embodiment, the adhesive layer is disposed between the positive electrode active material layer and the separator and between the negative electrode active material layer and the separator, but the present invention is not limited thereto. The adhesive layer may be disposed only between the positive electrode active material layer and the separator and between the negative electrode active material layer and the separator only between the active material layer having a larger flat area and the separator.

Further, the secondary battery of the present invention is not limited to the laminated battery as in the above embodiment, but may be a battery having another conventionally known structure such as a wound type battery.

Further, the secondary battery of the present invention is not limited to the non-bipolar type (internal parallel connection type) battery as in the above embodiment, but may be a battery of bipolar type (internal series connection type) But may be any other conventionally known battery which is different from the embodiment.

Further, the present invention is not limited to the lithium ion secondary battery, but can also be applied to, for example, a nickel hydrogen secondary battery.

10, 20, 30, 30A, 40, 40A, 50, 60: Lithium ion secondary battery (secondary battery)
100: Power factor
110: exterior material
120: positive pole collector plate
130: negative electrode collector plate
140: positive
141: positive electrode active material layer
142: Positive electrode collector
150: Negative
151: Negative electrode active material layer
152: anode collector
160: separator
170: adhesive layer
180: Adhesive layer

Claims (5)

A positive electrode comprising a positive electrode active material layer,
A negative electrode including a negative electrode active material layer,
A separator disposed between the positive electrode and the negative electrode,
And an adhesive layer disposed on at least one of the positive electrode and the separator and / or between the negative electrode and the separator, for bonding at least one of the positive electrode and the negative electrode to the separator,
A ratio of an area in which the adhesive layer is in contact with at least one of the positive electrode active material layer and the negative electrode active material layer in a range where the positive electrode active material layer and the negative electrode active material layer do not overlap with the overlapping range of the positive electrode active material layer and the negative electrode active material layer as viewed from the thickness direction of the active material layer And wherein the secondary battery is different from the secondary battery. The secondary battery according to claim 1, wherein the adhesive layer is in contact with at least one of the positive electrode active material layer and the negative electrode active material layer only in either the overlapping range or the non-overlapping range. The secondary battery according to claim 1 or 2, wherein the adhesive layers are disposed so as to avoid overlapping of the overlapping range and the non-overlapping range. The secondary battery according to claim 1 or 2, wherein the adhesive layer is disposed only in the overlapping range and the non-overlapping range, and also prevents permeation of ions. The secondary battery according to any one of claims 1 to 5, wherein the ratio of the maximum volume change of the charged state and the discharged state of the positive electrode active material layer and the negative electrode active material layer is 5% or more.

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