WO1999031751A1

WO1999031751A1 - Lithium ion secondary battery and its manufacture

Info

Publication number: WO1999031751A1
Application number: PCT/JP1997/004678
Authority: WO
Inventors: Kouji Hamano; Hisashi Shiota; Yasuhiro Yoshida; Michio Murai; Takayuki Inuzuka; Shigeru Aihara; Syo Shiraga
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1997-12-18
Filing date: 1997-12-18
Publication date: 1999-06-24

Abstract

A lithium ion secondary battery in which the electric connection between an active material layer and a separator can be maintained without using a solid casing, and the higher energy density and the optional forming such as thinning are possible, and which is excellent in charge and discharge property and is large in battery capacity. This plate-shaped lamination-structure battery is equipped with layers of electrodes laminates where projections and recesses are made at at least two faces, a face adjoining a separator of a positive electrode active material layer and a negative electrode active material layer and a face opposed to both active material layers of the separator, and the three members are joined and stuck fast to one another by adhesive resin layers, and also electrolytes including lithium ions are retained in the separator and the space made by the junction face of the projection and the recesses for electrical connection.

Description

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Details

: Next battery and its manufacturing method

The present invention relates to a lithium ion secondary battery in which a positive electrode and a negative electrode face each other with a separator holding an electrolyte therebetween. TECHNICAL FIELD The present invention relates to a battery structure which does not require an external metal can and can take any form such as a thin shape, and a manufacturing method for forming the structure. Height

There is a great demand for smaller and lighter portable electronic devices, and to achieve this, it is essential to improve battery performance. Therefore, in recent years, various batteries have been proposed and improved in order to improve the battery performance. Improvements in the characteristics expected of batteries include higher voltage, higher energy density, higher load resistance, arbitrary shape, and safety. Among them, the lithium-ion battery is the secondary battery that can realize the highest voltage, the highest energy density and the highest load among the existing batteries, and its improvement is being actively promoted even today.

This lithium ion secondary battery has, as its main components, a positive electrode, a negative electrode, and an ion conductive layer sandwiched between both electrodes. In a lithium-ion secondary battery that is currently in practical use, an active material powder such as a lithium-cobalt composite oxide is mixed with an electron conductor powder and a binder-resin 5 for a positive electrode and applied to an aluminum current collector. For the negative electrode, a carbon-based active material powder is mixed with a binder resin and applied to the copper current collector for the negative electrode. A plate shape is used. For the ion conductive layer, a porous film made of polyethylene or polypropylene filled with a non-aqueous solvent containing lithium ions is used.

For example, FIG. 9 is a schematic sectional view showing the structure of a conventional cylindrical lithium ion secondary battery disclosed in Japanese Patent Application Laid-Open No. 8-83608. In FIG. 9, 1 is an outer can made of stainless steel or the like also serving as a negative electrode terminal, 2 is an electrode body housed in the outer can 1, and 2 is a separator 5 disposed between the positive electrode 3 and the negative electrode 4. The electrode stack is spirally wound. The electrode assembly 2 needs to apply external pressure to the electrode assembly 2 in order to maintain electrical connection between the positive electrode 3, the separator 4, and the negative electrode 5. Therefore, the electrode body 2 is placed in the strong outer can 1 and pressurized to maintain contact between the above-described surfaces. In the case of prismatic batteries, a method has been used in which rectangular strips of electrode stacks are bundled and placed in a square metal can to apply force from the outside to hold them down.

As described above, in a current commercially available lithium ion secondary battery, a method of using a strong outer can made of metal or the like is used as a method of bringing the positive electrode and the negative electrode into close contact. Without an outer can, the surfaces of the electrode stack will peel off, making it difficult to maintain electrical connection and deteriorating battery characteristics. On the other hand, the weight and volume of the outer can occupying the entire battery not only lowers the energy density of the battery itself, but also limits the shape of the battery due to the rigidity of the outer can itself. Difficult to do.

Against this background, the development of lithium-ion rechargeable batteries that do not require strong outer cans is being pursued with the aim of reducing weight and thickness. The point of the development of batteries that do not require the above-mentioned outer can is to apply external force to the electrical connection between the positive and negative electrodes and the ion conductive layer (separate overnight) sandwiched between them. W

Three

It is how to maintain without doing. As one of the joining means that does not require such an external force, a method of adhering the positive electrode and the negative electrode to the separator using resin or the like has been proposed.

For example, Japanese Patent Application Laid-Open No. 5-159802 discloses a manufacturing method in which an ion-conductive solid electrolyte layer and a positive electrode and a negative electrode are integrated by heating using a thermoplastic resin binder. ing. In this case, the electrodes are brought into close contact by integrating the positive electrode and the negative electrode with the solid electrolyte layer, so that the electrical connection between the positive electrode, the negative electrode and the solid electrolyte layer is maintained without applying external force. Operates as a battery.

0 Conventional lithium-ion secondary batteries are configured as described above, and if a strong outer can is used to secure the adhesion between the positive and negative electrodes and the separation However, the ratio of the volume and weight of the outer can, which is not the outer part, to the entire battery is large, which is disadvantageous for producing a battery having a high energy density. In addition, a method of adhering the positive electrode and the negative electrode to the separator via an adhesive resin has been considered. For example, a solid electrolyte (a part equivalent to Separate) and the positive electrode and the negative electrode are simply adhered to each other via the adhesive resin. In this case, there is a problem that the resistance of the adhesive resin layer is large, so that the ionic conduction resistance inside the battery cell is increased and the battery characteristics are deteriorated.

0 Further, in the example of JP-A-5-158902, the positive electrode and the negative electrode and the solid electrolyte are joined with a binder, but the interface between the positive electrode and the negative electrode and the solid electrolyte is bound. Since it is covered with an agent, it is disadvantageous in terms of ionic conductivity as compared with, for example, the case where a liquid electrolyte is used. Even if a binder having ionic conductivity is used, a material having an ionic conductivity equal to or higher than that of the liquid electrolyte has not been generally found, and the same level of the battery using the liquid electrolyte has been found. There were problems such as difficulty in obtaining battery performance. W

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The present invention has been made as a result of intensive studies on a preferable bonding method between the separator and the positive electrode and the negative electrode in order to solve such a problem, and even without using a strong outer can. The positive electrode and negative electrode can be brought into close contact with the separator 5 without increasing the ion conduction resistance between the positive electrode and the negative electrode, enabling higher energy density, thinner, and multi-layered configurations of any form. An object of the present invention is to provide a compact and stable lithium ion secondary battery having excellent charge / discharge characteristics and a large battery capacity, and a method for manufacturing the same. 0 Disclosure of the Invention

The first configuration of the lithium ion secondary battery according to the present invention includes a positive electrode in which a positive electrode active material layer is joined to a positive electrode current collector, a negative electrode in which a negative electrode active material layer is joined to a negative electrode current collector, A plurality of electrode laminates each having a surface facing the surface of the layer and having a separator for holding an electrolyte containing lithium ions; The protrusions and recesses formed on the surface of the layer, and the protrusions formed by joining each of the facing surfaces and the surface of each of the active material layers adjacent to the facing surfaces with an adhesive resin layer. A void having a predetermined depth formed by the joint surface of the portion and the recess, and an electrolyte containing lithium ions held in the void and zero.

According to this, the adhesion between the positive electrode and the negative electrode active material layer and the separator can be ensured by the joint surface of the convex portion, and the electrolytic solution held in the gap formed by the joint surface of the convex portion and the concave portion allows Good ion conductivity between the positive and negative electrode active material layers and the separator can be ensured, so that high energy consumption is achieved. The following battery is obtained. In addition, due to the multilayered electrode stack, In addition, a stable, lightweight, compact battery with a large battery capacity can be obtained. In a second configuration of the lithium ion secondary battery according to the present invention, in the first configuration, the depth of the gap is set to 30 m or less.

This facilitates the diffusion of the reactive species, reduces the ionic conduction resistance between the positive electrode and negative electrode active material layers and the separator, and enables the use at a high load factor comparable to conventional liquid electrolyte batteries. Becomes possible.

A third configuration of the lithium ion secondary battery according to the present invention is the lithium ion secondary battery according to the first configuration, wherein an area of a bonding surface between the respective surfaces is 10 to 30% of a total area of the respective opposing surfaces. is there.

As a result, it is possible to suppress an increase in ionic conduction resistance between the positive electrode and negative electrode active material layers and the separation, and it is possible to use the battery at a high load factor that is not inferior to that of a conventional liquid electrolyte battery.

According to a fourth configuration of the lithium ion secondary battery according to the present invention, in the first configuration, the bonding strength between the separator and the positive electrode and the negative electrode active material layer is respectively equal to the positive electrode current collector and the positive electrode active material layer. And a bonding strength equal to or higher than the bonding strength between the negative electrode current collector and the negative electrode active material layer.

As a result, destruction of the electrode (peeling of the active material layer and the current collector) occurs more preferentially than peeling of the active material layer from the separator. Even if a strong outer can is not used, sufficient adhesion between the active material layer and the separator can be secured and maintained. According to a fifth configuration of the lithium ion secondary battery according to the present invention, in the first configuration, the adhesive resin layer is made porous.

Thereby, the ion conduction resistance between the positive electrode and the negative electrode can be further reduced.

According to a sixth configuration of the lithium ion secondary battery according to the present invention, in the first configuration, a void to which the adhesive resin layer is not attached is formed. Thereby, a further increase in ion conduction resistance can be suppressed. In a seventh configuration of the lithium ion secondary battery according to the present invention, in the first configuration, a plurality of layers of the electrode laminate are configured such that a positive electrode and a negative electrode are alternately arranged between a plurality of separated separators. It is formed by this. An eighth configuration of the lithium ion secondary battery according to the present invention is the lithium ion secondary battery according to the first configuration, wherein the plurality of layers of the electrode laminate are configured such that the positive electrode and the negative electrode are alternately arranged during the separated separation. It was formed. The ninth configuration of the lithium ion secondary battery according to the present invention is the ninth configuration according to the first configuration, wherein a plurality of layers of the electrode laminate are configured such that a positive electrode and a negative electrode are alternately arranged in a folded separator. It was formed.

According to the seventh to ninth configurations, a battery having excellent charge-discharge characteristics, light weight, small size, and a stable multilayer structure having a large battery capacity can be easily obtained. The method for manufacturing a lithium ion secondary battery according to the present invention includes a method of manufacturing a lithium ion secondary battery, comprising: a convex portion and a concave portion on at least two surfaces of one surface of a positive electrode active material layer, one surface of a negative electrode active material layer, and two opposite surfaces of a separator. Forming an adhesive resin layer on at least two surfaces of one surface of the positive electrode active material layer, one surface of the negative electrode active material layer, and two opposing surfaces of the separator. One surface of the positive electrode active material layer and one surface of the negative electrode active material layer are bonded to each surface of the separator and press-bonded, and a bonding surface formed by the convex portion and a predetermined depth formed by the concave portion. And a step of forming a plurality of layers of the electrode laminate having the above voids.

As a result, a compact, high-performance, multi-layer lithium ion secondary battery having a large battery capacity can be obtained simply and with good workability. In the production, an adhesive resin layer is locally adhered to form a void to which the adhesive resin layer is not adhered. This keeps the resistance between the positive and negative electrodes inside the battery low. it can. BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1, 2, and 3 are schematic cross-sectional views each showing a battery structure of an embodiment of the lithium ion secondary battery of the present invention, and FIG. 4 is a sectional view showing an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing an electrode laminate constituting such a battery, and FIG. 5 is an explanatory diagram showing a method of applying an adhesive resin liquid using a roll having micropores according to one embodiment of the present invention. FIG. 6 is an explanatory view showing a method of applying an adhesive resin liquid by screen printing according to one embodiment of the present invention, and FIG. 7 is a diagram illustrating an adhesion between a spray gun and a screen according to one embodiment of the present invention. FIG. 8 is an explanatory view showing a method of applying an adhesive resin liquid, FIG. 8 is an explanatory view showing a method of applying an adhesive resin liquid by a dispenser according to an embodiment of the present invention, and FIG. FIG. 2 is a schematic cross-sectional view illustrating an example of a secondary battery. BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to the drawings.

FIGS. 1, 2 and 3 are schematic cross-sectional views showing the battery structure of one embodiment of the lithium ion secondary battery of the present invention, and FIG. 1 shows a positive electrode 3, a separator 4, Figure 2 shows a flat laminated battery with multiple layers of electrode stacks formed by repeatedly stacking the negative electrode 5 in order. Fig. 3 shows a plate-shaped wound type laminated battery body in which a plurality of electrode laminates are formed by laminating a plurality of negative (positive) poles therebetween. A flat wound type laminated battery in which a pole is arranged, a strip-shaped negative (positive) pole is arranged on one side thereof, and the strip is wound into an elliptical shape to form a multi-layered electrode laminate. Showing body. FIG. 4 is a schematic sectional view showing an embodiment of the electrode laminate 8 constituting the battery according to the present invention. In the figure, reference numeral 3 denotes a positive electrode obtained by bonding a positive electrode active material layer 7 to a positive electrode current collector 6, 5 denotes a negative electrode obtained by bonding a negative electrode active material layer 9 to a negative electrode current collector 10, and 4 denotes a positive electrode 3 and a negative electrode. 5 is a separator that holds an electrolyte containing lithium ions, and is a surface of the separator 4 that faces the two active material layers 7 and 9 and the positive electrode active material layer 7 and the negative electrode active material layer 9. Convex portions and concave portions are formed on the surface adjacent (facing) the opposing surface of Separation 4. Reference numeral 1 denotes an adhesive resin layer for joining the opposing surface of the separator 4 to the surfaces of the adjacent active material layers 7 and 9, which are attached to the abutting projections to join the three members. Reference numeral 12 denotes a gap having a predetermined depth L formed between the electrode (that is, the active material layers 7 and 9) and the separator 4 and formed by the joint surface 11a of the protrusion and the recess. 2 holds an electrolyte containing lithium ions.

In this embodiment, the positive and negative electrode active material layers 7 and 9 are formed with concavities and convexities on opposing surfaces of the separator serving as the electrolyte layer, and the bonding surface 11 a of the convex portion is formed via the adhesive resin layer 11. Adhesion between the electrode and the separator can be ensured overnight, and peeling between the electrode and the separator can be suppressed, which was difficult with conventional batteries. The active material layers 7, 9 and the separation layer 4 are bonded and adhered with an adhesive resin, and at the same time, a gap having a predetermined depth formed by the bonding surface 11a of the convex portion and the concave portion therebetween. By holding the electrolyte inside 12, good ionic conductivity at the electrode-electrolyte interface can be ensured, and ionic conduction resistance can be reduced. Electrodes (Positive electrode and negative electrode) The amount of ions entering and exiting in the active material layer inside and the moving speed and amount of ions to the opposing electrode can be reduced to about the same level as those of conventional lithium ion batteries using an outer can. It becomes possible. The electrical connection between the active material layers 7 and 9 and Separation 4 can be maintained without applying external force. Therefore, to maintain the battery structure Eliminates the need for an outer can, which allows the battery to be lighter and thinner, has a multilayer structure of any shape, and has excellent charge / discharge characteristics and battery performance comparable to those of batteries using conventional electrolytes. Is obtained. Further, the battery capacity can be increased according to the number of layers of the electrode laminate.

In this embodiment, as shown in FIG. 4, the concave portions and the convex portions are regularly formed on the surfaces of the positive electrode and the negative electrode active material layers 7 and 9, and the separator 4, the positive electrode and the negative electrode are formed. The joining regions with the active material layers 7 and 9 are joined so that they coincide with each other on both surfaces of the separator 4. With this configuration, a strong bonding strength can be maintained even when a force acts on the bonding surface between the separator 4 and the positive electrode and negative electrode active material layers 7 and 9.

On the other hand, it is also effective when the concave and convex portions on both sides of Separation 4 are not coincident with each other. However, in such a structure, if a force acts on the joint surface between the separator 4 and the positive and negative electrode active material layers 7 and 9, the joint position is shifted on both surfaces of the separator and the screw is screwed into the separator 4. There is a disadvantage in that the force is applied in these directions, and the joint is slightly broken as compared with the structure of this embodiment.

Further, in this embodiment, irregularities are formed on both the positive and negative electrode active material layers 7 and 9 and Separation 4, but irregularities may be formed only on the positive and negative electrode active material layers 7 and 9. In addition, for example, a fluororesin having concaves and convexes formed on the surface is used as a separator, and the positive and negative electrode active material layers 7 and 9 have flat surfaces without irregularities. You may.

Furthermore, in this embodiment, the adhesive resin layer 11 is selectively formed in the joining region. However, for example, when a porous adhesive resin described later is used, the adhesive resin layer 11 is applied to the entire surface of the separator 4. You may do so. When the adhesive resin layer 11 is to be selectively formed in the joint area, the position of the convex portion and It is necessary to match the position of the dot of the adhesive resin layer 11. In this case, however, the adhesive resin may be applied to the entire surface, so that the adhesive resin layer can be easily formed.

In addition, in this embodiment, the injection of the electrolyte is performed by immersing the flat laminated battery body in the electrolyte and depressurizing the electrolyte, whereby the gas in the gap and the electrolyte are separated. This is easily achieved by substitution. After the injection, it is preferable to heat and dry the flat plate-shaped laminated battery.

Furthermore, after covering the flat plate-shaped laminated battery body with a flexible outer package, depressurizing the inside of the outer package, and adhering the outer surface of the flat laminated battery structure to the outer package, the outer package is formed. The electrolyte may be injected into the exterior body through the opening of the battery, the electrolyte may be injected into at least the gap, and finally, the opening of the exterior body may be sealed. According to this method, when the electrolytic solution is supplied, the back surface of the battery body and the exterior body are in close contact with each other, so that the electrolytic solution does not flow around to the back surface of the battery body, and unnecessary electrolysis that does not contribute to the electrolytic action is performed. The liquid can be eliminated, and the weight of the entire battery can be reduced. In addition, the depth L of the bonding surface 11 a of the convex portion and the gap 12 formed by the concave portion between the active material layers 7 and 9 and the separator 4 varies depending on the conductivity of the electrolyte, but usually, in the case of 1 0 'approximately ² S / cm is used, 3 if 0〃M less, the active material layer 7, 9 and separators Isseki ion conduction resistance between 4 becomes sufficiently small, the liquid electrolyte type battery Since it can be used at a high load factor not inferior to that of the above, it is preferable to set it to 30 zm or less. Further, by setting the depth L of the voids 12 to 10 / m or less, the diffusion of the reactive species proceeds more easily, so that the ionic conduction resistance can be further reduced. It is more desirable to adjust to. Further, in general, even if the solution is stirred, an adhesion layer of several μm (expansion) is formed on the surfaces of the active material layers 7 and 9 where an electrode reaction occurs. It is thought that diffusion of reactive species will proceed most easily by adjusting the depth L of the voids 12 to less than this value. Is most preferably several / m or less.

Also, by setting the area of 1 la of the bonding surface to 30% or less of the total area of each of the opposing surfaces of the active material layers 7 and 9 and the separation 4, the separation between the active material layers 7 and 9 and the separation Since the increase in ion conduction resistance during the evening can be suppressed, and it is possible to use the battery at a high load factor that is not inferior to conventional liquid electrolyte type batteries, it is desirable that the content be 30% or less. However, if the area of the bonding surface 11a is less than 10%, the bonding strength between the separator 4 and the positive electrode and negative electrode active material layers 7 and 9 becomes weak. Is preferably 10% to 30% of the total area of each facing surface, and most preferably adjusted to about 20%.

When the adhesive strength between the positive and negative electrode active material layers 7 and 9 and the separator 4 is sufficiently large, the peeling between the positive and negative electrode active material layers 7 and 9 and the separator 4 is larger than the separation between the positive and negative electrode active material layers 7 and 9 and the separator 4. Since the destruction of the active material layer (peeling of the active material layer and the current collector) occurs preferentially, the bonding strength between the separator 4 and the positive electrode and the negative electrode active material layers 7 and 9 is increased by the positive current collector 6 and the positive electrode current collector, respectively. It is desirable that the bonding strength between the active material layer 7 and the negative electrode current collector 10 and the negative electrode active material layer 9 be equal to or higher than the bonding strength.

Further, by making the adhesive resin layer 11 porous, it is possible to reduce the ionic conduction resistance in the adhesive resin layer and the joint, and it is possible to reduce the resistance between the electrodes. Furthermore, even if the adhesive resin layer 11 is adhered to the bonding surface 1 la, both surfaces of the separator 4 (opposite surface) or the entire surface of the active material layers 7 and 9 adjacent to this opposing surface, Since the ion conductivity can be secured through the micropores of the layer 11, the application of the adhesive resin layer 11 is facilitated. Further, by forming a void to which the adhesive resin layer 11 is not attached, the ion conduction resistance can be further reduced.

Then, the lithium ion secondary battery configured as described above is convex on at least two surfaces of one surface of each of the positive electrode active material layer 7 and the negative electrode active material layer 9 and two opposite surfaces of the separator 4. The step of forming a portion and a concave portion, the step of adhering a resin layer to at least two surfaces of one surface of each of the positive electrode active material layer 7 and the negative electrode active material layer 9 and two opposing surfaces of the separator 4, One surface of the positive electrode active material layer 7 and one surface of the negative electrode active material layer 9 are bonded to each surface of the night 4 and pressure-bonded, and the bonding surface 11a by the convex portion and the predetermined depth by the concave portion are formed. It is manufactured by performing a step of forming a plurality of layers of the electrode laminate 8 having the voids 12.

At this time, it is preferable to locally adhere the adhesive resin layer to a portion corresponding to the convex portion, and form a void 12 to which the adhesive resin layer 11 is not attached.

The following methods can be used to apply the adhesive resin layer 11 locally and to apply a large amount of adhesive resin to both surfaces of the separator 4 in a short time.

FIG. 5 is an explanatory view showing a method of applying an adhesive resin using a rotating roll having fine holes on the surface, where (a) is viewed from above and (b) is viewed from the side. Adhesive resin is filled inside the rotating roll 13 with micro holes 13 a on the surface, and pressure is applied to the inside of the rotating roll 13 with the pressurizer 16 to apply adhesive resin from the micro holes 13 a. Spill. At the same time, rotating the entire rotating roll 13 while moving the separating material 14 supplied from the separating roll 15 sandwiched between the rotating rolls 13, the separating material 1 4 Apply 1 7 in dots. Also, apply adhesive resin 17 in a dotted pattern to only one side of the separation material by this method. In addition, it is also possible to stack two sheets of separating material one on top of the other and sandwich them between the rotating rolls 13, and simultaneously apply the adhesive resin to one surface of each of the two separating materials.

Further, as shown in the explanatory view of FIG. 6, there is a method of applying an adhesive resin using a screen and a rotating roll in which dots or linear holes are formed. Separator screen 1 9 with holes 19 a opened in dot form Separation material 14 Installed near the surface of the material, Separation moving adhesive resin 17 from adhesive resin dropping port 20 By supplying the adhesive resin dropwise onto the screen 19 placed on the material 14 and rolling the supplied adhesive resin with the rotating roll 21, the shape of the holes 19 a of the screen 19 is reduced. The reflected adhesive resin 17 pattern is transferred to the separation evening material 14. By arranging at least two units on both surfaces of the separation material 14, the adhesive resin can be applied to both surfaces of the separation material 14 in a dot-like manner.

FIG. 7 is an explanatory view showing a method of applying an adhesive resin using a spray gun. Set up a screen 26 in the shape of a shower with holes in the form of dots, lines, or grids near the surface of the separation material 14 and dissolve the liquid adhesive resin or adhesive resin in the solvent. After filling the adhesive resin liquid into the spray gun 23, it is sprayed onto the separation material 14 through the screen 26. As a result, the adhesive resin 17 adheres on the separation material 14 in a shape corresponding to the holes of the screen 26, for example, in a dot shape. At least one spray gun 23 is arranged on each side of Separation Material 14 and at least one spray gun is continuously sprayed with the adhesive resin liquid while moving Separation Material 14. The adhesive resin can be applied in the form of dots. Note that a net or the like may be used instead of the screen 26.

Also, as shown in the explanatory diagram of FIG. At least one or more dispensers 28 filled with resin liquid are arranged, and the adhesive resin liquid is dropped intermittently as the separator 27 moves, so that the adhesive resin is applied in a dot-like manner. It may be. (A) is viewed from above and (b) is viewed from the side.

Examples of the active material provided in the present invention include, in the positive electrode, a composite oxide of lithium and a transition metal such as cobalt, nickel, and manganese; a chalcogen compound containing lithium; or a composite compound thereof. The above-mentioned composite oxides, chalcogen compounds containing lithium, or those having various additive elements in these composite compounds are used. In the negative electrode, graphitizable carbon, non-graphitizable carbon, polyacene, polyacetylene, etc. An aromatic hydrocarbon compound having an acene structure such as a carbon-based compound, billene, or perylene is preferably used, but any substance that can occlude and release lithium ions, which are the main components of battery operation, can be used. These active materials are used in the form of particles. The active material may have a particle diameter of 0.3 to 2 Ojm, and particularly preferably 0.3 to 5 zm.

As the binder resin used for forming the active material into an electrode plate, any resin that does not dissolve in the electrolytic solution and does not cause an electrochemical reaction inside the electrode laminate can be used. Specifically, homopolymers or copolymers such as vinylidene fluoride, ethylene fluoride, acrylonitrile, and ethylene oxide, and ethylene propylene diamine rubber can be used.

As the current collector, any metal can be used as long as it is stable in the battery. However, aluminum is preferably used for the positive electrode, and copper is preferably used for the negative electrode. The current collector may be in the form of foil, mesh, expanded metal, etc., but those having a large void area, such as meshed expanded metal, may be used after bonding. It is preferable in terms of facilitating the maintenance of the solution.

Separators can be made of any material having sufficient strength, such as an electronically insulating porous film, a net, and a non-woven fabric. The material is not particularly limited, but polyethylene and polypropylene are preferable from the viewpoint of adhesiveness and safety.

In addition, as a solvent and an electrolyte salt used for an electrolytic solution used as an ion conductor, a non-aqueous solvent and an electrolyte salt containing lithium used in a conventional battery can be used. Specifically, there are single solvents of ether solvents such as dimethoxetane, diethoxetane, getyl ether and dimethyl ether, single solvents of ester solvents such as propylene carbonate, ethylene carbonate, getyl carbonate and dimethyl ether, and the same solvents as described above. Alternatively, two kinds of mixed liquids composed of different solvents can be used. The electrolyte salt used for the _{electrolyte, L i PF 6, L i} A s F 6, L i C 1_Rei _{_{4, L i BF 4, L}} i CF 3 S 0 3, L i N (CF 3 S 0 _{_{2) 2, L i C (}} CF 3 S 0 2) 3, etc. _{_{L i N (C 2 F 5}} S 0 2) 2 can be used.

Also, the adhesive resin used to bond the current collector to the electrode and the adhesive resin used to bond the electrode to the separator are both insoluble in the electrolyte and do not cause an electrochemical reaction inside the battery. It is more preferable if it can be used and becomes a porous membrane. For example, a mixture mainly composed of a fluorine-based resin or a fluorine-based resin, or a mixture mainly composed of polyvinyl alcohol or polyvinyl alcohol A mixture is used. Specifically, a polymer or copolymer having a fluorine atom in its molecular structure, such as vinylidene fluoride or 4-fluoroethylene, a polymer or copolymer having vinyl alcohol in its molecular structure, or a polymer Methyl acrylate, polystyrene, polyethylene, polypropylene, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene Mixtures with such as can be used. In particular, polyvinylidene fluoride, a fluororesin, is suitable.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited by these examples.

Example 1

First, the fabrication of the positive electrode will be described.

L i C o 0 ₂ 8 7 parts by weight, 8 parts by weight of graphite powder, the positive electrode active material paste prepared by dispersing polyvinylidene fluoride vinylidene down the 5 parts by weight N- Mechirubi port Li Dong, Doc evening It was applied to a thickness of 30 by a single blade method to form an active material thin film. An aluminum net with a thickness of 30 μm serving as a positive electrode current collector is placed on the upper part, and a positive electrode active material paste adjusted to a thickness of 300 by the doctor blade method is applied on the upper part again to form a positive electrode. A laminate of the current collector and the positive electrode active material paste was produced. After leaving this laminate in a dryer at 60 ° C for 60 minutes to make it semi-dry, the gap between the rolls was adjusted to 400 / m using a rotary port to remove the laminate. By rolling to a thickness of 400 m, a positive electrode having an uneven shape on the surface of the positive electrode active material layer was produced. By sandwiching an aluminum mesh instead of a flat aluminum foil as a current collector, it is possible to create irregularities reflecting the shape of the mesh on the surface of the positive electrode active material layer 7. In this rolling step, the thickness of the electrode and the degree of the unevenness can be adjusted by adjusting the size of the gap between the rotary holes. Also, by changing the shape of the mesh (wire diameter, mesh size, porosity, etc.) of the positive electrode current collector, the shape of the unevenness formed on the surface of the positive electrode active material layer 7 can be changed. .

After this positive electrode was immersed in the electrolytic solution, the peel strength between the positive electrode active material layer and the positive electrode current collector was measured, and a value of 20 to 25 gf / cm was shown. Next, fabrication of the negative electrode will be described. Mesophase microbead carbon (trade name: Osaka Gas) 95 parts by weight, 5 parts by weight of polyvinylidene fluoride dispersed in N-methylpyrrolidone (abbreviated as NMP), and a negative electrode active material paste prepared by mixing The active material thin film was formed by applying a thickness of 300 μm by the method. A 20 / m-thick copper mesh serving as a negative electrode current collector is placed on the upper part, and a negative electrode active material paste adjusted to a thickness of 300 m by the doctor blade method is applied to the upper part of the copper mesh again. A laminate of a current collector and a negative electrode active material paste was prepared. After leaving the laminate in a dryer at 60 ° C for 60 minutes to make it semi-dry, the gap between the rolls was adjusted to 400〃m using a rotary port, and the laminate was Was rolled to a thickness of 400 μm so as to be in close contact with each other, thereby producing a negative electrode having an uneven shape on the surface of the negative electrode active material layer 9. Similarly to the positive electrode, by sandwiching a copper net instead of a flat copper foil as a current collector, irregularities reflecting the net shape can be created on the surface of the negative electrode active material layer 9.

After the negative electrode was immersed in the electrolytic solution, the peel strength between the negative electrode active material layer and the negative electrode current collector was measured, and a value of 10 to 15 / cm was shown. Next, a description will be given of the manufacture of a flat-plate laminated structure type battery shown in FIG. 1 having a plurality of electrode laminates in which a separator is joined between the positive electrode and the negative electrode.

First, 5 parts by weight of polyvinylidene fluoride and 95 parts by weight of N-methylpyrrolidone (hereinafter abbreviated as NMP) are mixed in a composition ratio, and the mixture is sufficiently stirred to form a homogeneous solution and viscous adhesiveness is obtained. A resin solution was prepared.

Next, one side of a 12-cm wide and 25-m-thick porous polypropylene sheet (Celgard # 2400) manufactured by Sephray, which is bundled in a roll of separe evening material. Then, the adhesive resin solution prepared as described above was applied.

Adhesive resin coating has micro holes 13a on the surface as shown in Fig. 5. This was performed using a rotating roll 13. The inside of the rotating roll 13 is filled with the above-mentioned adhesive resin liquid, and the adhesive resin liquid permeates through the minute holes 13a on the surface. Take out the separating material 14 from the separating roll 15 and rotate it while applying pressure to the inside of the rotating roll 13 having the minute holes 13 a on the separating material 14. Adhesive resin 17 could be applied to one side of Separet overnight material 14 in the form of dots. Also, the amount of the adhesive resin adhered could be adjusted by adjusting the pressure inside the rotating roll 13 and changing the discharge amount from the minute holes 13a. Prepare two separators 4 coated with adhesive resin on one side above, and before the resin liquid dries, sandwich the negative electrode 5 between the adhesive resin coated surfaces of the two separators, After being adhered to each other, they were placed in a 60 ° C. hot air drier for 2 hours to evaporate NMP, and the negative electrode was joined between the two separators. The two separators 4 joined together with the negative electrode 5 interposed therebetween are punched into a predetermined size, and the adhesive resin liquid prepared as described above is applied to one side of the punched separators in a dotted manner as described above. Then, the positive electrode 3 punched into a predetermined size was bonded, and a laminated body was formed in which the separator 4, the negative electrode 5, the separator 4, and the positive electrode 3 were joined in this order. Further, the adhesive resin liquid prepared above was applied to one surface of another separator which was punched into a predetermined size and joined with the negative electrode interposed therebetween, and the application surface of this separate separator was bonded to the first. The laminate was bonded to the positive electrode surface. This process is repeated to form a battery body having a plurality of electrode laminates in which the positive electrode and the negative electrode face each other across the separator, and the battery body is dried while being pressurized. A laminated battery body was manufactured.

The adhesive resin layer 11 becomes a porous film (adhesive resin layer) having holes communicating from the separation side to the positive electrode and the negative electrode side due to the evaporation of NMP with drying. The thickness of this adhesive resin layer is about lm W

19

Was.

Next, the current collectors connected to the respective ends of the positive electrode and the negative electrode current collectors of the flat plate-shaped laminated battery body were spot-welded to each other between the positive electrode and the negative electrode. Electrically connected in parallel. 5 Then, the flat plate-like layered structure cell body to the ethylene carbonate Jechiru as a solvent was injected electrolyte solution to the L i PF ₆ as a solute. At this stage, the peel strength of the positive electrode active material and the separator was measured, and the peel strength of the negative electrode active material and the separator was measured. The strengths were 25 to 30 gf / cm and 15 to 20 gfcm, respectively.

The lithium-ion secondary battery was manufactured by packing the flat-plate laminated battery body after the injection of the electrolytic solution with an aluminum laminate film, and performing heat sealing and sealing.

As described above, in this lithium ion secondary battery, the positive electrode 3, the separator 4, and the negative electrode 5 have the surface facing the two active material layers 7 and 9 of the separator 4 and the positive electrode 5 active material layer 7 and the negative electrode active material. A convex portion and a concave portion are formed on the surface of the layer 9 adjacent to the opposing surface of the separation layer 4.The adhesive resin layer 11 attached to the joint surface 1 la of the convex portion is in close contact with the convex portion. An electrolyte solution containing lithium ions is held in the voids 12 formed by the bonding surface 1 la and the recesses (generated according to the unevenness of the surface when the electrode and the separator are brought into close contact). 0 The active material layers 7 and 9 and the separator 4 are not completely covered with the adhesive resin layer 11 and the voids 12 hold the electrolyte so that the active material layers, and 9 and the separator 4 are separated. The increase in internal resistance during one night is suppressed, good ionic conductivity is ensured, and the active material layers 7, 9 and the separation part 4 are formed on the joint surface 1 la of the convex part by the adhesive resin layer 11. As a result, a thin, light-weight, high-capacity battery with excellent charge / discharge characteristics was obtained, which does not require external pressurization, that is, does not require a strong outer can. W

20

Further, in the present embodiment, the concave portions and convex portions shown in FIG. 4 are formed regularly on the surfaces of the positive electrode and negative electrode active material layers 7 and 9, and the separator 4 and the positive electrode and negative electrode active material layers 7 and 9 are formed. 9 is joined so that they coincide with each other on both sides of Separete 4 so that force acts on the joint surface between Separete 4 and the positive electrode 5 and the negative electrode active material layers 7, 9. In this case, strong bonding strength can be maintained.

Further, in this embodiment, only the positive and negative electrode active material layers 7 and 9 have irregularities. For example, a fluororesin having irregularities formed on its surface is used as the separator 4 and the positive and negative electrode active material layers are used. 7 and 9 may be those having a flat surface without forming concave and convex.

Furthermore, in the present embodiment, the adhesive resin layer 11 is selectively formed in the joining region, but may be applied to the entire surface of the separator 4. If the adhesive resin layer 11 is to be formed selectively in the bonding area, the position of the protrusion must match the position of the dot of the adhesive resin layer 11, but the entire surface of the separator 4 When the adhesive resin layer 11 is formed on the entire surface, the adhesive resin may be applied to the entire surface, so that the adhesive resin layer can be easily formed.

In addition, in the present embodiment, the injection of the electrolyte is performed by immersing the flat-plate laminated battery body in the electrolyte and depressurizing the electrolyte, thereby replacing the gas in the gap 12 with the electrolyte. This was easily achieved by: After the injection, the flat-plate-type laminated battery body was heated and dried.

Furthermore, the flat-plate laminated battery body is packed with an aluminum laminated film, the inside of the pack is decompressed, and the outer surface of the flat-layer laminated structure battery is brought into close contact with the film. 5 may be injected, and an electrolytic solution may be injected into at least the gap, and finally the opening may be sealed. According to this method, when supplying the electrolytic solution, the battery body is used. Since the back surface and the film are in close contact with each other, it is possible to prevent the electrolyte solution from flowing into the back surface of the battery body, to eliminate unnecessary electrolyte solutions that do not contribute to the electrolytic action, and to reduce the weight of the entire battery. .

In the present embodiment, the positive electrode 3 is closely adhered and bonded between the two separators 4 in the same manner as described above, and an adhesive resin liquid is applied to one surface of the separator 4 with the positive electrode 3 interposed therebetween. The process of pasting the negative electrode 5 on the application surface, and then pasting another positive electrode on the negative electrode 5 in which the positive electrode is pasted on the negative electrode 5 overnight may be repeated.

Example 2.

A viscous adhesive resin liquid prepared as the adhesive resin layer 11 shown in Example 1 by mixing the following compound in place of polyvinylidene fluoride and N-methylpyrrolidone in the same composition ratio Was used. Polytetrafluoroethylene

Copolymer of vinylidene fluoride and acrylonitrile

Mixture of polyvinylidene fluoride and polyacrylonitrile

Mixture of polyvinylidene fluoride and polyethylene oxide

Mixture of polyvinylidene fluoride and polyethylene terephthalate Mixture of polyvinylidene fluoride and polymethyl methacrylate

A mixture of polyfutsudani vinylidene and polystyrene

A mixture of polyfutsudani vinylidene and polyvinylene

Mixture of polyvinylidene fluoride and polyethylene

Using these adhesive resin liquids, a battery having a flat laminated battery body shown in FIG. 1 was produced in the same manner as in Example 1 above. When the peel strengths of the positive electrode active material layer 7 and Separation 4 and the negative electrode active material layer 9 and Separation 4 of this flat plate-shaped laminated battery were measured, the strengths were 15 to 70, respectively. gf / cm, converged to the range of 10 to 70 gf / cm. W

twenty two

Further, a lithium ion secondary battery was produced by injecting an electrolytic solution in the same manner as in Example 1 above, packing the package with an aluminum laminate film, and sealing it. As in Example 1, a battery that was thin, lightweight, excellent in charge / discharge characteristics, and large in battery capacity was obtained.

5 Example 3.

The positive electrode active material paste is applied to an aluminum mesh having a thickness of 30 m and an opening ratio of 70% by a doctor blade method so as to have a thickness of 300 / m, and dried at 60 ° C. After being left in the machine for 60 minutes, the positive electrode 3 was produced by pressing again to a thickness of 250 m. By this method, the difference between the peaks and valleys of the irregularities formed on the bonding surface (the surface adjacent to the separator 4) of the positive electrode 3 side of the positive electrode 3 of Example 10 above, that is, the bonding surface 1 of the convex portion The depth L of the void formed by la and the concave portion was 10 zm or less. Further, the negative electrode 5 was produced in the same manner using a copper net. Next, using the positive electrode 3 and the negative electrode 5 thus formed, an adhesive resin was locally applied to the separator 4 in a dotted manner in the same manner as in Example 1 to form the positive electrode 3 and the separator 5. Then, the anode 4, the negative electrode 5, and the separator 4 were joined and laminated in this order to produce a flat laminated battery as shown in Fig. 1.

In the electrode laminate 8 in this embodiment, the depth L of the gap is adjusted to 10 μm or less, so that diffusion of the reactive species proceeds more easily, and the active material layer 7,09—separate interface Since the ion conduction resistance of the battery can be reduced, a lithium ion secondary battery using the same can be used at a high load factor not inferior to a conventional liquid electrolyte battery. The depth L of the gap 12 can be adjusted by the pressing force during rolling when forming the positive electrode and the negative electrode, the wire diameter of the net, and the like. Example 4.

5 Coat the cathode active material base on an aluminum mesh having a thickness of 30 / m and an aperture ratio of 80% by a dough blade method so that the thickness becomes 300-1. After standing in a dryer at 60 ° C. for 60 minutes, it was pressed again so as to have a thickness of 200 / zm, and a positive electrode 3 in which convex portions and concave portions were formed on the surface of the active material layer 7 was produced. . Also, the negative electrode 5 was produced using a copper net in the same manner. Protrusions and depressions are also formed on the surface of the negative electrode active material layer 9. Next, in the same manner as in Example 1, the adhesive resin was applied in the form of dots, and the positive electrode 3, the separator 4, the negative electrode 5, and the separator 4 were sequentially joined and laminated, as shown in FIG. Such a flat-plate laminated battery body was manufactured. By this method, the area of the bonding surface 11a of the electrode laminate 8 was adjusted to 20% of the total area of each of the active material layers 7 and 9. Since the covering portion of the adhesive resin layer is 20%, in the battery using the same, it is possible to suppress an increase in the ionic conduction resistance between the active material layers 7 and 9, and it is not inferior to the conventional liquid electrolyte type battery. Use at a high load factor became possible. The area of 1 la of the joint surface is adjusted by the wire diameter of the net, the porosity, etc. It is adjusted by the shape of the active material layers 7 and 9 and the surface of the separator 4, and the application (adhesion) state of the adhesive resin. it can.

Embodiment 5.

The positive electrode active material base was applied to a 300-m-thick aluminum punching metal current-collecting base material with a thickness of 30 / m and an aperture ratio of 80% by the doctor blade method to a thickness of 300 m. After standing in a drier at 0 ° C. for 60 minutes, it was pressed again so as to have a thickness of 250 μm, thereby producing a positive electrode 3 in which projections and depressions were formed on the surface of the active material layer 7. Also, the negative electrode 5 was manufactured by forming a convex portion and a concave portion on the surface of the active material layer 9 using a copper-made punching metal in the same manner. Next, in the same manner as in Example 1, the adhesive resin was applied in the form of dots, and the positive electrode 3, the separator 4, the negative electrode 5, and the separator 4 were sequentially joined and laminated, as shown in FIG. A flat plate-shaped laminated battery body was produced. At this time, the depth L of the void 12 formed between the active material layers 7 and 9 and the separator 4 by the concave surface 11 a and the concave portion of the convex portion of the electrode laminate 8 is reduced to 10 μm or less. To be Adjusted. The depth L of the gap can be adjusted by the pressing force during rolling during electrode formation, the aperture ratio of the punched metal, the shape of the holes, and the like. By adjusting the depth of the voids to 10 m or less, diffusion of the reactive species proceeds more easily, so that the ionic conduction resistance of the active material layers 7 and 9 and the separator 4 can be reduced. It can be used at a high load rate that is not inferior to that of liquid electrolyte type batteries.

Embodiment 6.

The positive electrode active material paste was applied to a thickness of 300 zm on a punched aluminum current collecting base material with a thickness of 30 zm and an aperture ratio of 80% by the dough-blade method to a thickness of 300 zm. After standing in a dryer at 60 ° C. for 60 minutes, it was pressed again so as to have a thickness of 200 m, and a positive electrode 3 in which convex portions and concave portions were formed on the surface of the active material layer 7 was produced. Also, the negative electrode 5 was manufactured by forming a convex portion and a concave portion on the surface of the active material layer 9 using a copper-made punching metal in the same manner. Next, in the same manner as in Example 1, the adhesive resin was applied in the form of dots, and the positive electrode 3, the separator 4, the negative electrode 5, and the separator 4 were sequentially joined and laminated, and a flat plate as shown in FIG. A laminated battery structure was produced. According to this method, the area of 1 la of the bonding surface between the active material layers 7 and 9 and the separator was adjusted to 20% of the total area of each of the active material layers 7 and 9. 9 and Separation—The rise in ion conduction resistance in the evening can be suppressed, in other words, it can be reduced, making it possible to use the battery at a high load factor that is not inferior to conventional liquid electrolyte type batteries.

Embodiment 7.

The positive electrode active material paste is applied on a 30-μm-thick aluminum foil current-collecting base material to a thickness of 300 m by the Doc Yuichi Blade Method, and then dried in a 60 ° C dryer. After standing for 60 minutes, an expanded metal with a thickness of 30 3m and an aperture ratio of 20% is pressed on the surface of the active material paste, and the expanded metal is pressed. W

twenty five

The positive electrode 3 was produced by forming irregularities having a depth of 30 / m on the surface of the active material layer 7 by removing the metal, and then pressing again so that the total thickness became 250 / m. Negative electrode 5 was also produced in the same manner using a copper foil current collector. Next, in the same manner as in Example 1, the adhesive resin was applied in the form of dots, and the positive electrode 3, the separator 4, the negative electrode 5, and the separator 4 were sequentially joined and laminated. A flat laminated structure battery body as shown in the figure was produced. At that time, the depth L of the void 10 formed by the recesses on the surfaces of the active material layers 7 and 9 between the active material layers 7 and 9 and the separator 4 was adjusted to be 10 m or less. By adjusting the gap depth L to 10 m or less, zero diffusion of reactive species proceeds more easily, so that the increase in ion conduction resistance between the active material layers 7, 9 and the separator 4 can be suppressed. As a result, it has become possible to use the battery at a high load factor that is not inferior to liquid electrolyte batteries.

Example 8

The positive electrode active material paste is applied on a 30 / m-thick aluminum foil current-collecting base material 5 to a thickness of 300 m by a doctor blade method, and dried in a 60 ° C dryer. After standing for 60 minutes, a punching metal with a thickness of 30 / m and an aperture ratio of 20% is pressed on the surface of the active material paste, and the punching metal is removed to form irregularities with a depth of 30〃m on the electrode surface. After that, pressing was performed again so that the total thickness became 250 μm, and a positive electrode was produced. Negative electrode 5 was also prepared in the same manner using a copper foil current collector.

Next, in the same manner as in Example 1, the adhesive resin was applied in the form of dots, and the positive electrode 3, the separator 4, the negative electrode 5, and the separator 4 were sequentially joined and laminated, as shown in FIG. A flat plate-shaped laminated battery body was produced. With this method, the area of the junction surface 11a between the active material layers 7, 9 and the separator 4 was adjusted to 20% of the total area of the active material layers 7, 59, so that the active material layers 7, 9 and the separator were separated. The rise in ionic conduction resistance during one night can be suppressed, and the conventional liquid electrolyte It can be used at a high load rate that is not inferior to a rechargeable battery.

Embodiment 9.

In this example, a battery was manufactured in the same manner as in Example 1 except that only the method of applying the adhesive resin liquid was changed. As shown in Fig. 6, a porous polypropylene sheet with a width of 12 cm and a thickness of 25 m (available from Hoechst # 24) 0 0) was taken out, and a shingle-shaped screen 19 having a hole 19 a in a dot shape having a diameter of 100 μm was pressed onto the separation material 14. The adhesive resin liquid shown in Example 1 was dropped on the screen 19, and the adhesive resin was rolled from the screen at the coating port 21 to form a dot-like adhesive resin liquid on the separator. Transfer coating was possible. In the same manner, the adhesive resin liquid was successfully applied to the two separators 4 sandwiching the negative electrode 5 therebetween. Similarly, when the adhesive resin liquid shown in Example 2 was used, the adhesive resin liquid could be applied favorably in the form of dots on a separate plate. In this way, a lithium secondary battery having the same excellent characteristics as in Example 1 above was obtained even when the separation resin to which the adhesive resin layer was attached was used.

Example 10

Also in this example, a battery was manufactured in the same manner as in Example 1 except that only the method of applying the adhesive resin liquid was changed. As shown in Fig. 7, a porous polypropylene sheet with a width of 12 cm and a thickness of 25 / m (Hoechst Celgard # 2400) is used as a material for separating material 14 and bundled in a roll. Then, a beaker-like screen 26 with holes formed in the shape of dots was placed in the vicinity of the surface of the material 14 for separation. Next, the adhesive resin liquid was sprayed onto the separation material 14 using the spray gun filled with the adhesive resin liquid shown in Example 1. Spraying evenly on the surface of Separation material 14 The adhesive resin liquid was applied in a dot-like manner. In the same manner, the adhesive resin liquid was applied favorably to the two separators 4 joined together with the negative electrode 5 interposed therebetween. In addition, the amount of the adhesive resin adhered could be adjusted by changing the spray speed. Similarly, in the case where the adhesive resin liquid shown in Example 2 was used, the adhesive resin liquid could be satisfactorily applied to the separation material in a dot-like manner. Thus, a lithium secondary battery having the same excellent characteristics as in Example 1 above was obtained using Separation overnight to which the adhesive resin layer was adhered. Example 11 1.

Also in this example, a battery was manufactured in the same manner as in Example 1 except that only the method of applying the adhesive resin liquid was changed. As shown in Fig. 8, a roll of 12 cm wide and 25 mm thick porous polypropylene sheet (Hoechst Cell Guard # 2) 400) was taken out, and the adhesive resin liquid shown in Example 1 was filled into eight dispensers 28 arranged on one side of the separation material 14. This adhesive resin liquid was applied intermittently to the surface of the separation material 14 at the same time as the separation resin material 14 was moved, whereby the adhesive resin solution could be applied in a dot-like manner. In the same manner, the adhesive resin liquid was successfully applied in a dotted manner to the two separators 4 joined together with the negative electrode 5 interposed therebetween. Similarly, when the adhesive resin liquid shown in Example 2 was used, the adhesive resin liquid was successfully applied to both surfaces of the separator. Similarly, a lithium secondary battery having excellent characteristics was obtained by using Separation overnight to which the adhesive resin layer was adhered.

Example 1 2.

The preparation of the negative electrode 5 and the positive electrode 3 and the preparation of the adhesive resin liquid were performed in the same manner as in Example 1 above. The adhesive resin liquid prepared on one side of each of the two strip-shaped separators 4 was used as in Example 1 above. In the same manner, apply in the form of dots After sandwiching the strip-shaped positive electrode between the two surfaces, bonding them together and placing them in a hot-air dryer at 60 ° C for 2 hours, evaporating the NMP of the adhesive resin solution, and separating the two sheets in the evening The positive electrode was joined.

The prepared adhesive resin solution is applied to one surface of the strip-shaped separator with the positive electrode interposed therebetween in a similar manner in a dot-like manner, and one end of the separator is placed with this one surface in the middle. The negative electrode 5 cut into a predetermined size was sandwiched between the folds and the fold, and the pieces were overlaid and passed through Lamine overnight. Subsequently, the adhesive resin liquid prepared above was applied to the other surface of the strip-shaped separator in a dot-like manner in the same manner, and the predetermined size was applied to a position facing the negative electrode 5 sandwiched between the folds. A process of bonding another cut negative electrode, winding the strip-shaped separator into an elliptical shape for half a turn so as to sandwich the negative electrode, and further winding the separate separator while bonding another negative electrode, is repeated to form a plurality of layers. A battery body having the above electrode laminate was formed, and this battery body was dried while being pressurized to produce a flat-plate wound type laminated structure battery body as shown in FIG.

The current collectors connected to the ends of each of the negative electrode current collectors of the flat-plate-shaped laminated battery body were electrically connected in parallel by spot welding. Further, the flat wound type laminated structure battery body was impregnated with an electrolytic solution in the same manner as in Example 1 and sealed to obtain a secondary battery.

Also in this flat-plate wound type laminated structure battery body, similarly, the positive electrode 3 and the negative electrode 5 and the separator 4 are in close contact with each other by the adhesive resin layer 11 attached to the joint surface of the convex portion, and Since good ion conductivity can be ensured by the retained electrolyte, a thin, light-weight, large-capacity battery with excellent charge / discharge characteristics that does not require a strong outer can was obtained.

In the present embodiment, an example is shown in which a strip-shaped positive electrode 3 is joined between strip-shaped separators 4 while being wound up, and a plurality of negative electrodes 5 having a predetermined size are sandwiched therebetween. Conversely, the strip-shaped negative electrode 5 is placed between the strip-shaped separators 4. A method may be used in which a plurality of the positive electrodes 3 having a predetermined size are sandwiched therebetween while the joined members are wound up.

Further, in this embodiment, the method of winding the separator 4 has been described, but the band-shaped seno, which is formed by joining the band-shaped negative electrode 5 or the positive electrode 3 between the layers 4, is folded into a predetermined size. A method in which the positive electrode 3 or the negative electrode 5 is sandwiched therebetween and bonded together may be used.

Example 13

The production of the negative electrode 5 and the positive electrode 3 and the preparation of the adhesive resin solution are performed in the same manner as in Example 1 above.

The strip-shaped positive electrode 3 is arranged between two strip-shaped separators 4, and the strip-shaped negative electrode 5 is arranged so as to protrude outside the one separator by a certain amount. In advance, the prepared adhesive resin liquid is applied to the inner surface of each separator 4 and the outer surface of the separator 4 on which the negative electrode 5 is to be disposed, in a dot-like manner by the above-described coating method. A predetermined amount of one end of the negative electrode 5 is passed through Lamine overnight, and then a negative electrode 5, Separe night 4, Positive electrode 3 and Separe night 4 are laminated to form a laminar laminate. did. Then, the prepared adhesive resin liquid is applied to the outer surface of the other separator in the band-shaped laminate, and the protruded negative electrode 5 is bent and bonded to the coated surface, and the bent negative electrode 5 is bonded. The laminated body that has been laminated is wrapped in an elliptical shape so as to be wrapped inside, to form a battery body having a plurality of electrode laminates as shown in FIG. 3, and this battery body is dried while being pressurized. Then, the negative electrode, the separator, and the positive electrode were simultaneously bonded to produce a flat-plate-type laminated battery.

An electrolytic solution was injected into the flat wound type laminated structure battery body in the same manner as in Example 1 and sealed to obtain a battery. As in the case of Example 1 above, a battery having a small thickness, light weight, excellent charge / discharge characteristics, and a large battery capacity was obtained.

In the present embodiment, a strip-shaped positive electrode 3 is arranged between strip-shaped separators 4. In the example shown above, the negative electrode 5 is placed outside the separator 4 and rolled up. Conversely, the belt-like negative electrode 5 is placed between the belt-like separator 4 and the other separator is placed outside the separator 4. A method of arranging and winding the positive electrode 3 may be used.

In the above example, when the number of layers was changed variously, the battery capacity increased in proportion to the number of layers. Industrial applicability

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

Claims

The scope of the claims

1. A positive electrode in which a positive electrode active material layer is joined to a positive electrode current collector, a negative electrode in which a negative electrode active material layer is joined to a negative electrode current collector, and a surface facing each of the above active material layers, and lithium A plurality of electrode stacks each having a separator holding an electrolyte solution containing ions, a convex portion and a concave portion formed on the opposing surface or the surface of each active material layer adjacent to the opposing surface; A predetermined surface formed by bonding the convex portions and the concave portions formed by bonding the respective opposing surfaces and the surfaces of the respective active material layers adjacent to the opposing surfaces with an adhesive resin layer. A lithium ion secondary battery including a gap having a depth and an electrolyte containing lithium ions held in the gap.

2. The lithium ion secondary battery according to claim 1, wherein the depth of the void is 30 μm or less.

3. The lithium ion secondary battery according to claim 1, wherein an area of a bonding surface between the respective surfaces is 10 to 30% of a total area of the respective opposing surfaces.

4. The bonding strength between the separator and the positive and negative electrode active material layers is equal to or higher than the bonding strength between the positive electrode current collector and the positive electrode active material layer and between the negative electrode current collector and the negative electrode active material layer, respectively. 2. The lithium-ion secondary battery according to item 1.

5. The lithium ion secondary battery according to claim 1, wherein the adhesive resin layer is porous.

6. The lithium ion secondary battery according to claim 1, wherein a void to which the adhesive resin layer is not attached is formed.

7. The method according to claim 1, wherein the plurality of layers of the electrode laminate are formed by alternately arranging a positive electrode and a negative electrode during a plurality of separated separations. Lithium ion secondary battery.

8. The multiple layers of the electrode stack, the positive electrode and the negative electrode 2. The lithium ion secondary battery according to claim 1, wherein the lithium ion secondary battery is formed by alternately arranging the lithium ion batteries during a laser beam.

9. The lithium ion secondary battery according to claim 1, 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. battery.

10. a step of forming convex portions and concave portions on at least two surfaces of one surface of the positive electrode active material layer, one surface of the negative electrode active material layer, and two opposing surfaces of the separator; Adhering an adhesive resin layer to at least one of the one surface of the negative electrode active material layer and the two opposing surfaces of the separator; and forming the positive electrode on each surface of the separator. One surface of the active material layer and one surface of the negative electrode active material layer are bonded and pressure-bonded to form an electrode laminate having a bonding surface formed by the convex portions and a gap having a predetermined depth formed by the concave portions. A method for producing a lithium ion secondary battery, comprising the steps of:

11. The method according to claim 10, wherein the adhesive resin layer is locally adhered to form a void to which the adhesive resin layer is not adhered.

'Rechargeable battery manufacturing method.