WO1999031750A1

WO1999031750A1 - Adhesive for cells, a cell using the same and a process for producing cells

Info

Publication number: WO1999031750A1
Application number: PCT/JP1997/004677
Authority: WO
Inventors: Michio Murai; Takayuki Inuzuka; Yasuhiro Yoshida; Shigeru Aihara; Daigo Takemura; Hisashi Shiota; Jun Aragane; Hiroaki Urushibata; Kouji Hamano
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1997-12-18
Filing date: 1997-12-18
Publication date: 1999-06-24

Abstract

An adhesive for easily adhering an electrode and a separator, a cell using the same, and a process for producing cells, in order to obtain practical secondary cells having a reduced thickness and excellent charge/discharge characteristics. The adhesive for cells works to adhere active substance layers (3, 6) adhered to collectors (2, 5) to a separator (7) which holds an electrolytic solution for a cell. The adhesive comprises an organic solvent solution containing a polyvinyl alcohol. Use of the above adhesive makes it possible to cheaply and efficiently produce practical secondary cells having a reduced thickness, secured reliability and a high charge/discharge efficiency.

Description

TECHNICAL FIELD The present invention relates to a battery adhesive, a battery using the same, and a method for manufacturing a battery.

The present invention relates to a secondary battery used for portable electronic devices and the like. More specifically, the present invention relates to an adhesive capable of forming a high-performance battery in a thin shape, a battery using the same, and a method for manufacturing the battery. is there. Background art

There is a great demand for smaller and lighter portable electronic devices, but in order to achieve this, it is essential to improve the performance and size of batteries, and various battery developments and improvements are currently being pursued. I have. The characteristics required for batteries include high voltage, high energy density, reliability, and arbitrary shape. Lithium-ion batteries are secondary batteries that are expected to achieve the highest voltage and highest energy density among batteries to date, and improvements are being actively pursued today.

A lithium ion battery has a positive electrode, a negative electrode, and an ion conductive layer sandwiched between them as main components. In a lithium-ion battery currently in practical use, a positive electrode is formed by applying a powder of lithium cobalt oxide or the like as an active material to a current collector to form a plate, and a negative electrode is similarly made of a carbon-based material as an active material. Is applied to a current collector and applied on a plate. The ion conductive layer is filled with a non-aqueous electrolyte with a separator made of a porous film made of polyethylene and polypropylene interposed therebetween.

For conventional lithium-ion batteries, for example, As shown in the publication, in order to maintain the electrical contact between the positive electrode, the separator, and the negative electrode, by applying pressure from the outside with a strong outer can made of metal or the like, all in-plane contact is maintained. Need to keep.

Further, for example, in the example of the solid secondary battery described in Japanese Patent Application Laid-Open No. 5-159802, a layer of an ion-conductive solid electrolyte and a layer of an electrode material are heated with a thermoplastic resin binder. A manufacturing method is shown in which a battery is integrated by binding. In this case, since the electrodes and the electrolyte are integrated to maintain electrical contact, they function as a battery without external pressure. Further, as for a thin battery, as described in U.S. Pat. No. 5,460,904, a battery using a polymer gel as an ionic conductor is known. By using vinylidene fluoride and hexafluoropropylene copolymer as the gel, the positive electrode, separator and negative electrode are integrated.

Since the conventional battery is configured as described above, in order to make the electrode layer and the electrolyte layer electrically contact sufficiently, use a strong outer can made of metal or the like that can apply pressure from the outside. As a result, the ratio of the outer case other than the power generation unit to the volume and weight of the battery has increased, and there has been a problem that it is disadvantageous to form a battery with a high energy density.

In a battery in which an electrode layer and an electrolyte layer are joined with a binder, the electrode-electrolyte interface is covered with a solid binder. This is disadvantageous compared to a battery that uses a liquid electrolyte and applies pressure from the outside with an outer can. Also, even when a binder is used, a binder having conductivity equal to or higher than that of the liquid electrolyte has not been generally found, and the same conductivity as that of a battery using the liquid electrolyte cannot be obtained. Further, even in a thin battery using a polymer gel, a gel electrolyte having a conductivity equal to or higher than that of a liquid electrolyte has not been generally found, and it is possible to obtain the same charge / discharge characteristics as a battery using a liquid electrolyte. Can not.

The present invention has been made in order to solve the above-mentioned problems, and the electrode-electrolyte can be formed without using a strong outer can for applying pressure from the outside by joining the electrode layer and the electrolyte layer. An adhesive that forms an electrode body having good electrical contact between layers, and is intended to obtain a thin, lightweight, highly reliable battery with excellent charge / discharge characteristics at low cost and efficiency. It is. Disclosure of the invention

The first battery adhesive according to the present invention is an adhesive for bonding an active material layer bonded to a current collector to a separator for holding a battery electrolyte, and the adhesive is It consists of an organic solvent solution containing polyvinyl alcohol. This makes it possible to achieve high adhesiveness between each active material layer and the separator and high charge-discharge characteristics of the battery, and is a practical battery that is thin, has high reliability, and has high charge-discharge characteristics. Can be obtained at low cost. The second battery adhesive according to the present invention is the resin according to the first battery adhesive, wherein the resin is incompatible with polyvinyl alcohol in an organic solvent solution and swells or dissolves in a battery electrolyte. Are further mixed. Thereby, the ion conductivity of the interface layer between each active material layer formed by the adhesive and the separation layer can be made higher.

A third battery adhesive according to the present invention is the above-mentioned first battery adhesive, wherein the degree of saponification of polyvinyl alcohol is 95% or more. A fourth battery adhesive according to the present invention is the first battery adhesive, wherein the degree of polymerization of polyvinyl alcohol is 100 or more. Thereby, a battery having high bonding strength and more preferable characteristics can be obtained. In the first battery according to the present invention, the active material layers of the positive electrode and the negative electrode each having the active material layer adhered to the current collector are separated from the active material layer for holding the battery electrolyte, and the organic solvent contains polyvinyl alcohol. It has an electrode laminate bonded with a battery adhesive. As a result, it is possible to achieve high adhesion between each active material layer and the separator and high charge / discharge characteristics of the battery, and realize a thin, reliable, and practical battery with high charge / discharge characteristics. It can be obtained at low cost.

The second battery according to the present invention is the battery according to the first battery, wherein the battery adhesive is further incompatible with polyvinyl alcohol and further swells or dissolves in the battery electrolyte. It becomes. Thereby, the ionic conductivity of the interface layer between each active material layer formed by the adhesive and the separation layer can be made higher.

A third battery according to the present invention is the same as the first battery, except that the third battery includes a plurality of layers of the electrode laminate.

A fourth battery according to the present invention is a battery according to the third battery, wherein a plurality of layers of the electrode laminate are formed by alternately arranging a plurality of layers of the positive electrode and the negative electrode separated from each other. is there.

According to a fifth battery of the present invention, in the third battery, a plurality of layers of the electrode laminate are formed by alternately arranging the positive electrode and the negative electrode between the wound separators.

According to a sixth battery of the present invention, in the third battery, a plurality of layers of the electrode laminate are formed by alternately arranging a positive electrode and a negative electrode in a folded separator.

In the present invention, since the adhesive strength and high ionic conductivity can be ensured, a strong outer can is required even in a configuration having a plurality of layers of the electrode laminate. In addition, a compact, high-performance, large-capacity stacked electrode battery can be obtained.

The first method for producing a battery according to the present invention comprises the steps of:

A step of applying an adhesive for a battery containing a battery to the surface of the separator, and a step of bonding the active material layers of the pair of electrodes having the active material layer bonded to the current collector to the application surface of the separator. The method includes a step of integrating the above-mentioned electrode and the separator by removing at least a part of the organic solvent. As a result, it is possible to achieve high adhesion between each active material layer and the separator and high charge / discharge characteristics of the battery, and it is thin and reliable, and practically has high charge / discharge durability. Battery can be obtained at low cost.

The method for producing a second battery according to the present invention is the method for producing a battery according to the first battery, wherein the adhesive for a battery is applied to the surface of the separator, and then the adhesive for the battery is applied to the application surface of the separator. The method further comprises a step of gelling the battery adhesive by adding a second solvent capable of gelling the adhesive solution. Thereby, the ionic conductivity of the interface layer between each active material layer formed by the adhesive and the separator can be further increased. A third method for producing a battery according to the present invention is the method for producing a battery according to the first method, wherein the battery adhesive is incompatible with polyvinyl alcohol in the organic solvent solution and swells in the battery electrolyte. Alternatively, it is obtained by further mixing a soluble resin. Thereby, the ionic conductivity of each active material layer formed by the adhesive and the interface layer between the separation and the evening can be made higher. In a fourth method for producing a battery according to the present invention, the saponification degree of polyvinyl alcohol is 95% or more in the first method for producing a battery.

A fifth method for producing a battery according to the present invention is the method for producing a battery according to the first method, wherein the degree of polymerization of polyvinyl alcohol is 100 or more. You.

Thereby, a battery having high bonding strength and more preferable characteristics can be obtained. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cross-sectional view of a main part of an embodiment of a battery according to the present invention. FIGS. 2, 3, and 4 show other embodiments of the battery according to the present invention. It is a principal part cross-section schematic diagram demonstrated. BEST MODE FOR CARRYING OUT THE INVENTION

The present inventors have conducted intensive studies on a preferred method of bonding the active material layer surfaces of a pair of electrodes having the active material layer bonded to the current collector to the separator, and have reached the present invention.

That is, as shown in FIGS. 1 to 4, the present invention provides a positive electrode 1 in which a positive electrode active material layer 3 is bonded to a positive electrode current collector 2, and a negative electrode 4 in which a negative electrode active material layer 6 is bonded to a negative electrode current collector 5. The present invention relates to a battery having an electrode laminate 9 in which a separator 7 holding an electrolytic solution between a positive electrode 1 and a negative electrode 4 is joined by an adhesive layer 8.

A feature of the present invention resides in the composition of the battery adhesive forming the adhesive layer 8 that joins the electrodes (positive and negative electrodes) 1 and 4 and the separator.

The present inventor has conducted various studies on a secondary battery that has been studied as to how thin and reliable the battery is, and how to increase the charge / discharge efficiency. The inventors have found that a thin and reliable secondary battery with high charge / discharge efficiency can be manufactured by using, and the present invention has been completed.

That is, according to the research of the present inventor, as the battery adhesive for the adhesive layer 8, for example, “Poval” (Koichi Nagano et al. Polymer Publishing Association Showa 45 First Edition By using polyvinyl alcohol, which is used as an adhesive as described in “Issues”, as a battery adhesive, the adhesive develops a strong adhesive force, and the battery can be integrated with a small amount of adhesive. The adhesive strength obtained can be obtained, and the adhesive layer 8 is made porous by drying and removing the solvent in the adhesive, or the adhesive layer 8 is gelated by partially distilling off the solvent. 8, the ionic conductivity can be increased, and the charge / discharge characteristics can be improved.

Also, a mixture of polyvinyl alcohol and another resin can be used. In particular, by using a resin that is incompatible with polyvinyl alcohol and that dissolves or swells in the battery electrolyte, the adhesive layer 8 is incompatible with polyvinyl alcohol and a phase exhibiting an adhesive function. A battery having particularly excellent performance can be obtained by having a resin electrolyte and a resin that dissolves or swells in the battery electrolyte and has two phases, ie, a phase that exhibits ionic conduction.

The degree of saponification of polyvinyl alcohol is preferably 95% or more, and the degree of polymerization of polyvinyl alcohol is preferably 100 or more.

After applying the battery adhesive containing polyvinyl alcohol to the organic solvent on the surface of the separator, the active material layer of the pair of electrodes having the active material layer bonded to the current collector is applied to the coating surface of the separator. After laminating, at least a part of the organic solvent is distilled off to integrate the electrode and the separator to produce a single electrode laminate 9 shown in FIG. As described above, by removing at least a part of the organic solvent, a part of the adhesive layer 8 is gelled when the electrolytic solution is injected, and the ionic conductivity of the adhesive layer 8 is increased, and the charge / discharge characteristics are excellent. A battery is obtained.

FIG. 1 shows a single-electrode battery composed of a single electrode stack 9; As shown in FIGS. 3 and 4, a stacked electrode battery having a structure having a plurality of electrode stacks 9 can be manufactured. This manufacturing method will be described in detail in the following examples.

Further, after the battery adhesive is applied to the surface of the separator, a second solvent capable of gelling the battery adhesive solution is added to the coating surface of the separator, thereby forming the battery. The adhesive for use is gelled, the ionic conductivity of the adhesive layer 8 is increased, and the battery performance can be improved.

As a solvent for gelling the battery adhesive solution, any solvent that does not dissolve polyvinyl alcohol can be used. For example, hydrocarbons, ketone compounds, ester compounds, ether compounds, alcohols and the like and mixed solvents thereof can be used.

In addition, by using a battery adhesive further mixed with a resin which is incompatible with polyvinyl alcohol in an organic solvent solution containing polyvinyl alcohol and which can swell or dissolve in a battery electrolyte. As described above, the adhesive layer 8 has two phases of a phase exhibiting an adhesive function and a phase exhibiting ionic conduction, and a battery having particularly excellent performance can be obtained.

Examples of the resin that is incompatible with the polyvinyl alcohol and that dissolves or swells in the battery electrolyte include polystyrene, polyacrylate, polyacrylonitrile, polyvinyl acetate, polyacetal, and mixtures or copolymers thereof. it can.

As the battery electrolyte, a solution in which a lithium salt is dissolved in a non-protonic organic solvent can be used. The lithium salt _{L i C 10 4, L iBF} 4, L iAs F 6, L i CF 3 S0 3, L i PF 6, L il, L iB r, L i S CN, L i 2 B 10 C l ₁₀ , Li CF ₃ C〇 _{2 and the} like. As aprotic organic solvents, propylene glycol, butyl lactone, ethylene glycol, tetrahydrofuran, 2-tetrahydrofuran Drofuran, 1,3-dioxolan, 4,4-dimethyl-1,3-dioxolan, getylcapone, dimethylcapone, sulfolane, 3-methylsulfolane, tert-butylether, iso-butylether, 1 , 2-Dimethoxetane, 1,2-ethoxymethoxetane, and the like, and a mixed solvent obtained by combining them can be used.

As the organic solvent constituting the adhesive, N-methyl-2-pyrrolidone, dimethylsulfoxide, acetoamide, arptyrolactone, and the like, and a mixed solvent obtained by combining these can be used.

In some cases, a filler such as an inorganic oxide can be added to the battery adhesive. In this case, since the adhesive layer 8 becomes porous by adding the filler, it is expected that the ionic conductivity of the adhesive layer 8 is improved and the battery characteristics are improved.

As the separator used during the production of the battery, any material having sufficient strength, such as a porous film made of an electrically insulating material, a net, and a nonwoven fabric, can be used. The material is not particularly limited, but a single porous film or a laminated porous film of polyethylene or polypropylene is preferable from the viewpoint of battery performance.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The adhesive strength of the battery was 180 degrees of the test piece (20 mm XI 00 mm X 0.2 mm) in which the positive electrode 1, the negative electrode 4 and the separator 7 were bonded together with an adhesive. The peel strength was measured. UTM11-20 manufactured by Toyo Baldwin Co., Ltd. was used as a test device, and the measurement was performed at a tensile speed of 10 mm / min and a measurement temperature of 25 ° C.

The battery charge / discharge characteristics were measured under the following conditions, for example, using the method described in the Battery Handbook (Battery Handbook Editing Committee, published by Maruzen Publishing Co., Ltd. in 1990). did.

Charging: constant current + constant voltage method, upper limit voltage 4.2 V

Discharge: Constant current method Lower limit voltage 2.5 V

Battery electrode capacity: 100 mAh

Charge / discharge current value: 100mA

Charge / discharge efficiency (%) = Discharge electric capacity-Charge electric capacity X 100

Example 1.

L i C 00 ₂ to 87 wt%, the graphite powder 8% by weight, the positive electrode active material pace preparative adjusting the Porifudzu mold two isopropylidene 5 wt%, the thickness 300〃M at Doc evening one blade method The active material thin film was formed by coating while adjusting. An aluminum net having a thickness of 30 / zm serving as a positive electrode current collector was placed on the upper part thereof, and a positive electrode active material paste was applied thereon by adjusting the thickness to 300 μm by a doctor blade method. This was left in a dryer at 60 ° C for 60 minutes to make it semi-dry. A positive electrode was produced by rolling the produced laminate to 40 O / m.

A negative electrode active material paste adjusted to 95% by weight of mesophase microbeads (Osaka Gas) and 5% by weight of polyvinylidene fluoride is applied by a doctor blade method while adjusting the thickness to 300 mm. An active material thin film was formed. A 20-m-thick strip-shaped copper net serving as a negative-electrode current collector was placed on the upper portion, and a negative-electrode active material paste was applied thereon by adjusting the thickness to 300-m by a doctor blade method. This was left in a dryer at 60 ° C. for 60 minutes to make it semi-dry. A negative electrode was produced by rolling the produced laminate to 400 zm.

<Formulation of adhesive> 3 g of polyvinyl alcohol having a polymerization degree of 300 and a saponification degree of 98 mo 1% was added to 97 g of N-methyl-2-pyrrolidone (NMP), and heated to 80 ° C to form a solution while stirring.

Porous polypropylene sheet (to text, trade name Celgard # 2400) used as a separator evening the adhesive 3mg applied per separator Isseki 1 cm ² to, there to be brought into close contact with the positive and negative electrodes becomes a predetermined thickness Then, it was heated at 80 ° C for 1 hour and then cut into a predetermined size.

Porous polypropylene sheet (to text, trade name Celgard # 2400) used as separator Isseki adhesive separator evening 1 cm ² per then 3mg coated according to claim 1 or later on both sides of where adhesion to the positive electrode and the negative electrode Then, after laminating so as to have a predetermined thickness, it was heated and breathed under a vacuum of 80 ° C for 1 hour to obtain an electrode laminate. Further, by inserting the electrode laminate Arumiramine one Tofuirumu bag, under vacuum, Weight ratio of ethylene carbonate Jechiru 1: comprising a _{L i PF 6 1 mo 1/} 1 was dissolved in 1 mixed solvent of electrolyte After impregnation with the liquid, the film was sealed by heat sealing to produce a film-shaped single-electrode battery (size: 10 Ommx 100 mmx 0.4 mm).

Example 2.

Instead of the adhesive in Example 1, 3 g of polyvinyl alcohol having a polymerization degree of 1000 and a saponification degree of 98 mol% was added to 97 g of N_methyl-1-piperidone, heated to 80 ° C. and stirred. The solution that was used while the solution was used.

Example 3. Instead of the adhesive in Example 1, 3 g of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 98 mol% was added to 97 g of N-methyl-2-piperone, heated to 80 ° C. and stirred. The solution that was used while the solution was used.

Example 4.

Using the positive electrode and the negative electrode described in Example 1 above, an adhesive was prepared in the following manner, and a test piece for an adhesive strength test and a battery were prepared.

3 g of polyvinyl alcohol having a polymerization degree of 300 and a saponification degree of 98 mo 1% was added to 97 g of N-methyl-2-pyrrolidone, and the mixture was heated to 80 ° C. and stirred to form a solution.

The above adhesive was applied to a porous polypropylene sheet (made by Hext, product name Celgard # 2400) used as a separator overnight, 3 mg per cm ² of the separator, and isopropyl alcohol was sprayed on the application surface. Thereafter, the positive electrode and the negative electrode were brought into close contact with each other so as to be bonded to a predetermined thickness, heated and pressed at 80 ° C. for 1 hour, and then cut into a predetermined size.

Separator used as Isseki porous polypropylene sheet (to kiss preparative trade name Celgard # 2400) adhesive separator Isseki 1 cm ² per 3 mg coated according to claim 1 or later on both sides of carbonate coating surface After spraying getyl with a sprayer, the positive electrode and the negative electrode were adhered to each other so as to have a predetermined thickness, and heated and pressed under a vacuum of 80 ° C. for 1 hour to obtain an electrode laminate. Further, this electrode laminate is inserted into an aluminum laminate film bag, and impregnated with an electrolyte solution obtained by dissolving LiPF6 in a mixed solvent of ethylene carbonate and getyl carbonate at a weight ratio of 1: 1 in lmo 1/1 under reduced pressure. After heating A single electrode battery (size:

100 mm X 10 Ommx 0.4 mm).

Example 5.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a polymerization degree of 1000 and a saponification degree of 98 mol% was added to 97 g of N-methyl-2-vinylidone, and the mixture was heated to 80 ° C. and stirred. The solution was used as it was.

Example 6.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 98 mol% was added to 97 g of N-methyl-2-pyrrolidone, and the mixture was heated to 80 ° C. and stirred. The solution was used.

Example 7.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a polymerization degree of 300 and a saponification degree of 87 mo 1% was added to 97 g of N-methyl-2-pyrrolidone, and the mixture was heated to 80 ° C. and stirred. A solution was used. Example 8.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a degree of polymerization of 1000 and a degree of saponification of 87 mol% was added to 97 g of N-methyl-12-piperidine, heated to 80 ° C. and stirred. The solution that was used while the solution was used.

Example 9.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 87 mol% was added to 97 g of N-methyl-2-bilidone, and the mixture was heated to 80 ° C. and stirred. The solution was used. Example 10

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a degree of polymerization of 300 and a degree of saponification of 98% mo, and 3 g of polymethyl methacrylate were converted to 94 g of N-methyl-2-pyrrolidone. In addition, a solution which was heated to 80 ° C. and stirred while stirring was used.

Example 11 1.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a degree of polymerization of 100 and a saponification degree of 98%, and 3 g of polymethyl methacrylate were replaced with 94 g of N-methyl-2-pyrrolidone. In addition to 80. A solution which was heated to C while stirring was used.

Example 1 2.

Instead of the adhesive in Example 4, 3 g of polyvinyl alcohol having a degree of polymerization of 240 and a saponification degree of 98 mol%, and 3 g of polymethyl methacrylate were added to 94 g of N-methyl-2-pyrrolidone. The solution was heated to 80 ° C. and stirred to form a solution.

Example 13

The preparation of the negative electrode and the positive electrode and the adjustment of the adhesive were performed in the same manner as in Example 1 above. The adjusted adhesive was applied to one surface of each of the two separators, and the negative electrode was sandwiched between the coated surfaces. Then, the NMP was put in a hot air drier at 80 ° C. for 2 hours to evaporate NMP.

The separator with the negative electrode bonded in between was punched out to a predetermined size, the adhesive adjusted above was applied to one surface of the punched-out separator, and the positive electrode punched to a predetermined size was stuck, Further, the above-prepared adhesive was applied to one surface of another separator punched out to a predetermined size, and the coated surface of the separate separator was bonded to the surface of the positive electrode previously bonded. This step is repeated to form a battery body having a plurality of electrode laminates. The pond was dried while being pressurized to produce a flat-plate laminated battery as shown in FIG.

An electrolytic solution was injected into the plate-shaped laminated structure battery body in the same manner as in Example 1 and sealing was performed to obtain a lithium ion secondary battery.

In this example, an adhesive was applied to the surface of the separator where the positive electrode was adhered and adhered in the same manner as described above, and the negative electrode was adhered to the coated surface. The step of bonding another positive electrode with two positive electrodes bonded together during one separation may be repeated.

Example 14.

The preparation of the negative electrode and the positive electrode and the adjustment of the adhesive were performed in the same manner as in Example 1 described above. The adjusted adhesive was applied to one surface of each of the two strip-shaped separators, and a belt-shaped adhesive was applied between the applied surfaces. After the positive electrode was sandwiched and adhered to each other, it was placed in a hot air drier at 60 ° C for 2 hours to evaporate N-methyl-2-pyrrolidone.

The adjusted adhesive was applied to one side of the strip-shaped separator with the positive electrode bonded between them, one end of the separator was bent by a certain amount, the negative electrode was sandwiched in the fold, and the laminate was passed through the laminator. . Subsequently, the adjusted adhesive is applied to the other side of the strip-shaped separator, and another negative electrode is attached to a position opposite to the negative electrode sandwiched between the folds, and the separator is rolled up in an oval shape. Further, the step of winding up the separator while attaching another negative electrode is repeated to form a battery body having a plurality of electrode laminates, and the battery body is dried while being pressed, and is then pressed as shown in FIG. A wound-type laminated structure battery body was produced. An electrolytic solution was poured into the plate-shaped wound laminated battery body in the same manner as in Example 1 described above, and the battery was sealed to obtain a lithium ion secondary battery.

In the present embodiment, an example is shown in which the negative electrode is adhered to the belt-shaped separator while the band-shaped positive electrode is joined and rolled up in the evening. In the evening, a method in which the positive electrode is bonded while the band-shaped negative electrode is joined is rolled up.

Further, in this embodiment, the method of winding up the separator is shown, but a method of bonding the positive electrode or the negative electrode while folding the band-shaped negative electrode or the positive electrode in the band-shaped separator may be used.

Example 15

Preparation of the negative electrode and the positive electrode, and adjustment of the adhesive are performed in the same manner as in Example 1 above. The strip-shaped positive electrode is placed between two strip-shaped separators, and the strip-shaped negative electrode is placed so as to protrude outside of one of the separators by a certain amount. The adjusted adhesive is applied to the inner surface of each separator and the outer surface of the separator where the negative electrode is placed, and the positive electrode, the two separators and the negative electrode are overlapped and passed through the laminator. The adjusted adhesive is applied to the outer surface of the other separator, and the protruding negative electrode is bent and adhered to this coated surface, and the laminated separator is wrapped inside so that the folded negative electrode is long. It is rolled up in a circular shape to form a battery body having a plurality of electrode laminates, and the battery body is dried while being pressurized to form a flat-plate wound type laminated structure battery body as shown in FIG. Made.

An electrolytic solution was poured into the plate-shaped wound type laminated structure battery body in the same manner as in Example 1 and sealed to obtain a lithium ion secondary battery.

In the present embodiment, an example is shown in which a strip-shaped positive electrode is arranged in a strip-shaped separator and a negative electrode is arranged outside one separator and rolled up, but conversely, a strip-shaped separator is formed in a strip-shaped separator. A method in which a negative electrode is arranged, and a positive electrode is arranged outside one separator and wound up may be used.

In Examples 13 to 15 described above, as a result of changing the number of layers in various ways, the battery capacity increased in proportion to the number of layers.

Comparative Example 1. 17 Instead of the adhesive in Example 4, 3 g of polyvinylidene fluoride was added to 97 g of N-methyl-2-pyrrolidone, and a solution was used while heating to 80 ° C. and stirring.

Comparative example 2.

In place of the adhesive in Example 4 above, 6 g of polyvinylidene fluoride was added to 94 g of N-methyl-2-pyrrolidone, and the mixture was dried. The solution which was heated to C and stirred while stirring was used.

Comparative example 3.

Instead of the adhesive in Example 4, 3 g of poly (methyl methacrylate) was added to 97 _g of N-methyl-2-pyrrolidone, and the mixture was heated to 80 ° C. and stirred to form a solution. . Table 1 Adhesive strength Battery charge / discharge characteristics Positive electrode-separator Negative electrode-separator

1 Δ △ 〇

Out 2 〇〇〇

Example 3 〇〇〇

4 〇. Δ 〇

5 ◎ 〇〇

6 ◎ ◎ 〇

7 Δ Δ 〇

8 〇 0 〇

9 〇〇 "〇

10 〇〇〇

11. ◎ ◎. 〇

12 © ◎ 〇

Ratio 1 X X X

Comparison 2 Δ Δ. X

Example 3 XXX Using the adhesive test pieces obtained in the above Examples and Comparative Examples, the adhesive strength of the adhesive was determined according to the following criteria (1) and (2). The results are shown in Table 1 above.

◎: Peel adhesion between electrode and separator is 80 gf / cm or more 〇: Peel adhesion between electrode and separator is 60 gf / cm or more

Δ: The peel adhesion between the electrode and the separator was 40 gf / cm or more. X: The peel adhesion between the electrode and the separator was less than 40 gf / cm. Also, the batteries obtained in the above Examples and Comparative Examples were used. The charge-discharge was repeated for 100 cycles, and the charge and discharge characteristics at the first cycle and at the 100th cycle were determined based on the following criteria of X and X. The results are shown in Table 1 above.

〇: Charge and discharge efficiency is 70% or more

X: The charging / discharging efficiency is less than 70% or charging / discharging is impossible. As clearly shown in the results in Table 1 above, according to Examples 1 to 12, according to Examples 1 to 12, between the positive electrode 1 and the separator 7 and between the negative electrode 4 -Batteries with high adhesive strength during separation and excellent battery charge / discharge characteristics can be obtained.

In particular, in Examples 4 to 12 using the production method in which the adhesive was applied to the separator and then the second solvent for gelling the adhesive was added to the coating surface of the separator, the positive electrode 1-separator was used. The bonding strength between the negative electrode 7 and the negative electrode 4 and the separator 7 was increased. This is because the adhesive solution gels and the amount absorbed into the porous electrode active material layer decreases, resulting in the amount of adhesive remaining at the electrode-separator interface and contributing to the development of adhesive strength. This is thought to be the result of the increase.

In addition, the use of polyvinyl alcohol, which has a high degree of saponification, The adhesive strength between the separator 7 and the anode 4 and the separator 7 was increased. This is considered to be because the polyvinyl alcohol solution having a higher degree of saponification can be more effectively gelled by the gelling solvent.

As shown in Comparative Example 1, when polyvinylidene fluoride was used for the adhesive, the positive electrode 1 and the separator were used irrespective of the same resin concentration and adhesive application amount as compared with Examples 1 to 12. Adhesive strength sufficient to integrate overnight 7 and negative electrode 4 as a battery could not be obtained.

Further, as shown in Comparative Example 2, when polyvinylidene fluoride was used as the adhesive and the concentration of the adhesive solution was increased to twice that of Examples 1 to 12, sufficient adhesive strength was obtained. However, the charge / discharge characteristics of the battery deteriorated.

In addition, as shown in Comparative Example 3, even when methyl methacrylate was used as the adhesive, the positive electrode 1 and the positive electrode 1 had the same resin concentration and adhesive application amount as compared with Examples 1 to 12. Adhesive strength sufficient to integrate separator 7 and negative electrode 4 as a battery could not be obtained.

Although the results in Table 1 above are shown for Examples 1 to 12, similar results were obtained for the stacked electrode type batteries shown in Examples 13 to 15. Industrial applicability

It is used as a secondary battery in portable electronic devices such as mobile personal computers and mobile phones, and can be made smaller, lighter, and arbitrarily shaped as well as improving battery performance.

Claims

The scope of the claims

1. An adhesive for adhering the active material layer adhered to the current collector to a separator for holding a battery electrolyte, the adhesive being made of an organic solvent solution containing polyvinyl alcohol. An adhesive for a battery, comprising:

2. The adhesive for a battery according to claim 1, wherein the organic solvent solution is further mixed with a resin that is incompatible with polyvinyl alcohol and swells or dissolves in an electrolyte solution for a battery. Agent.

3. The battery adhesive according to claim 1, wherein the degree of saponification of polyvinyl alcohol is 95% or more.

4. The adhesive for batteries according to claim 1, wherein the degree of polymerization of polyvinyl alcohol is 100 or more.

5. An electrode in which the active material layers of a pair of electrodes in which the active material layer is bonded to the current collector are bonded with a battery adhesive containing polyvinyl alcohol in an organic solvent during the separation for holding the battery electrolyte. A battery having a laminate.

6. The battery according to claim 5, wherein the battery adhesive is further mixed with a resin that is incompatible with polyvinyl alcohol and swells or dissolves in the battery electrolyte.

7. The battery according to claim 5, comprising a plurality of layers of the electrode laminate.

8. The battery according to claim 7, wherein the plurality of layers of the electrode laminate are formed by alternately arranging the positive electrode and the negative electrode in a plurality of separated separators.

9. The plurality of layers of the electrode laminate are formed by alternately arranging a positive electrode and a negative electrode in a wound separator.

The battery according to item 7.

10. The battery according to claim 7, wherein the plurality of layers of the electrode laminate are formed by alternately arranging a positive electrode and a negative electrode in a folded separator.

1 1. Separate the battery adhesive containing polyvinyl alcohol into the organic solvent.

—Applying the active material layer on the evening surface, attaching the active material layer of the pair of electrodes with the active material layer adhered to the current collector to the application surface of the separator, removing at least part of the organic solvent A process for integrating the electrode and the separator with the above method.

1 2. After applying the battery adhesive to the surface of the separator, the second solvent capable of gelling the battery adhesive solution is added to the coating surface of the separator. 12. The method for producing a battery according to claim 11, further comprising a step of gelling the battery adhesive.

13. The battery adhesive according to claim 11, wherein the battery adhesive is further mixed with a resin that is incompatible with polyvinyl alcohol in an organic solvent solution and swells or dissolves in a battery electrolyte solution. 13. The method for producing a battery according to the above item.

14. The method for producing a battery according to claim 11, wherein the degree of saponification of polyvinyl alcohol is 95% or more.

15. The method for producing a battery according to claim 11, wherein the degree of polymerization of polyvinyl alcohol is 1000 or more.