WO1999041797A1

WO1999041797A1 - Lithium ion secondary battery

Info

Publication number: WO1999041797A1
Application number: PCT/JP1998/000608
Authority: WO
Inventors: Kouji Hamano; Yasuhiro Yoshida; Michio Murai; Takayuki Inuzuka; Hisashi Shiota; Shigeru Aihara; Daigo Takemura; Jun Aragane; Hiroaki Urushibata
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1998-02-16
Filing date: 1998-02-16
Publication date: 1999-08-19

Abstract

A lithium ion secondary battery which is capable of airtightly adhering a positive and a negative pole to a separator without using a strong outer packaging can and increasing a resistance between the poles, and which can have a high energy density, can be made thin and formed into any shape, and has excellent charging and discharging characteristics. The lithium ion secondary battery is provided with an electrode laminate having a positive pole (3) made by putting a positive pole active material layer (32) and a positive pole current collector (31) together, a negative pole (5) made by putting a negative pole active material layer (52) and a negative pole current collector (51) together, a separator (4) located between the positive pole active material layer (32) and the negative pole active material layer (52), and adhesive resin (6) which is located in parts of a space between each of the active material layers (32, 52) and the separator (4) so that spaces (7) to connect each of the active material layers (32, 52) and the separator (4) may be formed. An electrolyte including lithium ions is retained in the spaces (7), the separator (4), the positive pole active material layer (32), and the negative pole active material layer (52). Due to this structure, the active material layers and the separator can be airtightly adhered to each other by means of the adhesive resin without using an outer packaging can. The electrolyte is retained in the spaces formed by forming adhesive resin non-existence sections, and so a good ion conduction can be secured between the positive and the negative pole active material and the separator.

Description

Description Lithium-ion secondary battery technology

The present invention relates to a lithium ion secondary battery in which a positive electrode and a negative electrode face each other across a separator holding an electrolyte, and more specifically, to improve the electrical connection between the positive electrode and the negative electrode and the separator. The present invention relates to a battery structure that does not require a strong metal outer can and can take any shape such as a thin shape. Background art

The demand for smaller and lighter portable electronic devices has been greatly increased, and in order to achieve this, it is indispensable to improve the performance of secondary batteries, which are the power source for them. In recent years, various batteries have been developed and improved in order to improve the battery performance. Higher voltage, higher energy density, higher load resistance, arbitrary shape, and safety are currently considered to improve the characteristics expected of batteries, but lithium ion batteries are currently available. It is considered to be the most excellent secondary battery in terms of high voltage, high energy density, high load resistance, etc. among batteries that can be used, and improvements are being actively made to improve its characteristics even today.

In general, a battery has a positive electrode, a negative electrode, and an ion conductive layer sandwiched between both electrodes as its main components. In a round or square lithium-ion secondary battery currently in practical use, the positive electrode is made of fine particles of active material such as lithium-cobalt oxide and electron conductor particles and a binder resin that binds them. A plate that is mixed and coated on an aluminum current collector to form a plate is used, and a fine powder of active material such as graphite or non-graphitizable carbon is used for the negative electrode. For example, a material mixed with a binder resin and applied to a copper current collector to form a plate is used. As the ion conductive layer, a porous membrane such as polyethylene or polypropylene filled with a non-aqueous solvent containing lithium ions is used.

For example, FIG. 11 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. 11, 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 inside the outer can 1, and 2 is a positive electrode 3, a separator 4 and a negative electrode 5. It has a spirally wound structure. The electrode body 2 needs to apply external pressure to the electrode body 2 in order to maintain electrical connection between the opposing surfaces of the positive electrode 3, the separator 4, and the negative electrode 5. For this purpose, the electrode body 2 is placed in a strong outer can 1 and pressurized to maintain the above-mentioned contact between the surfaces. For rectangular batteries, a method of bundling strip-shaped electrode bodies into a rectangular metal can, and applying force from the outside to hold them down is used. As described above, in current commercially available lithium ion secondary batteries, as a method of bringing the positive electrode and the negative electrode into close contact with each other, a method of applying pressure using a strong outer can made of metal or the like is used. As described above, without the outer can, the opposing surfaces of the electrode body 2 are separated, so that it is difficult to maintain the electrical connection, and the battery characteristics deteriorate. On the other hand, this outer can has a large weight and volume occupying the entire battery, which not only causes a decrease in the energy density of the battery as a whole, but also the outer can itself is rigid, so the battery shape is Because it is limited, it is difficult to make it into an arbitrary shape. 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 key to the development of a battery that does not require such an outer can is how to make the electrical connection between the positive and negative electrodes and the ion conductive layer sandwiched between them without applying external force. Is to maintain it.

As one of the joining means that does not require such external force, a method of adhering the positive electrode and the negative electrode to the ion conductive layer using a 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 integrally formed by heating using a thermoplastic resin binder containing lithium ions. I have. According to this manufacturing method, since the positive electrode and the negative electrode and the solid electrolyte layer as the ion conductive layer are completely adhered to each other with the ion conductive resin binder, the positive electrode and the negative electrode can be connected to the solid without any external force. The electrical connection between the electrolyte layers is maintained and operates as a battery.

However, in the example of JP-A-5-159802, since the interface between the positive electrode and the negative electrode and the solid electrolyte is entirely covered with the binder, the electrical connection between each electrode and the solid electrolyte deteriorates. . That is, in this example, a solid resin binder having ion conductivity is applied to the entire surface of the electrode, but at present, a solid resin material having ion conductivity equal to or higher than that of the liquid electrolyte has not been generally found. However, it is difficult to obtain the same level of battery performance as a battery using a liquid electrolyte because it is not possible to secure an electrical connection between the electrode and the ionic conductor to the same extent as a battery using a liquid electrolyte. I got a point.

In order to solve the above problems, the present invention has been made as a result of intensive studies by the present inventors on a preferable method of adhesion between the positive electrode and the negative electrode and the ion conductive layer. The positive and negative electrodes and the ionic conductor can be brought into close contact with each other without using them and without increasing the resistance between the electrodes. An object of the present invention is to provide a lithium ion secondary battery having excellent electric characteristics. Disclosure of the invention A first lithium ion secondary battery according to the present invention includes a positive electrode formed by bonding a positive electrode active material layer to a positive electrode current collector; a negative electrode formed by bonding a negative electrode active material layer to a negative electrode current collector; Each of the active material layers and the separator are arranged so as to form a gap communicating between the active material layer and the negative electrode active material layer, and a gap communicating between each of the active material layers and the separator. An electrode laminate having an adhesive resin partially disposed during the evening, wherein an electrolyte containing lithium ions is held in each of the voids, the separator, and each active material layer. is there. According to this battery, by using the adhesive resin, the active material layer and the separation can be brought into close contact with each other without using an outer can. Therefore, good ion conductivity between the positive electrode active material layer and the negative electrode active material layer and the separator can be ensured. Therefore, there is an effect that a lithium ion secondary battery which can have a high energy density and a low thickness and has excellent charge / discharge characteristics which can take any shape can be obtained.

In the second lithium ion secondary battery according to the present invention, in the first battery, the area of the void is 30% to 9% of the area of each facing surface where each active material layer faces the separator. 0%. According to this battery, there is an effect that the ionic conduction resistance between the electrodes can be reduced while maintaining sufficient adhesion between the electrodes and the separator.

A third lithium ion secondary battery according to the present invention is the above-described first battery, wherein a distance between each active material layer surface and a separation is 30 / m or less. According to this battery, the ionic conduction resistance between the active material layer and the separator can be sufficiently reduced, and there is an effect that the battery can be used at a high load factor that is not inferior to a battery using a conventional outer can.

The fourth lithium ion secondary battery according to the present invention is the above first battery, wherein an electronic insulating resin which is solid at room temperature is used as the adhesive resin. It was what was. According to this battery, in the manufacturing process, the adhesive resin is heated to increase the fluidity and is applied to an arbitrary position, and once cooled to room temperature to reduce the fluidity, the active material layer and the separator are separated. After that, the resin is heated again to re-melt the resin and bond the active material and the separator, so that the gap area and the distance between the active material layer and the separator can be adjusted to the desired values. There is an effect that a battery whose value is controlled can be easily manufactured.

A fifth lithium ion secondary battery according to the present invention is the same as the first battery, except that the fifth lithium ion secondary battery has a plurality of electrode laminates.

The sixth lithium ion secondary battery according to the present invention is the battery according to the fifth battery, wherein the plurality of layers of the electrode laminate are formed by alternately arranging a positive electrode and a negative electrode between a plurality of separated separators. It was formed.

A seventh lithium ion secondary battery according to the present invention is the above-described fifth battery, wherein the plurality of layers of the electrode laminate are formed by alternately arranging the positive electrode and the negative electrode during the separated separation. It was formed.

An eighth lithium-ion secondary battery according to the present invention, in the above-mentioned fifth battery, wherein the plurality of layers of the electrode laminate are formed by alternately arranging the positive electrode and the negative electrode during the folded separation. It was done.

In the first battery, it is possible to achieve both high adhesive strength between the electrode and the separator overnight and high ionic conductivity. Further, as a result, it is possible to form a structure in which a plurality of electrode laminates that do not require a strong outer can are laminated, that is, a structure of a laminated electrode type battery such as a separated laminated type, a wound type, and a folded type. In the fifth to eighth lithium ion secondary batteries described above, a lithium ion secondary battery having a compact, large capacity, and stable battery characteristics is obtained by forming a stacked electrode type battery structure. be able to. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic cross-sectional view showing a battery structure of a lithium ion secondary battery according to one embodiment of the present invention, and FIG. 2 is a diagram showing a coating of an adhesive resin according to one embodiment of the present invention. FIG. 3 is a schematic view showing an example of a method, FIG. 3 is a schematic view showing another example of a method of applying an adhesive resin according to an embodiment of the present invention, and FIG. FIG. 5 is a schematic diagram showing another example of the method of applying the adhesive resin according to one embodiment. FIG. 5 is a schematic view showing another example of the method of applying the adhesive resin according to one embodiment of the present invention. FIG. 6 is a schematic view showing another example of the method for applying the adhesive resin according to one embodiment of the present invention, and FIG. 7 is a diagram showing a lithium ion according to one embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing a secondary battery, and FIGS. 8, 9 and 10 show a lithium battery according to another embodiment of the present invention. A schematic cross-sectional view showing a cell structure of the ion secondary battery, the first 1 figure because a cross-sectional view schematically showing a conventional lithium-ion secondary battery. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is applied to a battery having a structure in which a positive electrode and a negative electrode and a separator are arranged between the positive electrode and the negative electrode. In the following embodiment, a single-layer electrode battery mainly composed of a single electrode stack of a positive electrode, a separator, and a negative electrode will be described, but a stacked electrode battery in which a single electrode stack is stacked will be described. Also applicable to

FIG. 1 is a schematic cross-sectional view showing a battery structure of a lithium ion secondary battery according to an embodiment of the present invention, that is, a structure of an electrode stack. In FIG. A positive electrode joined to the current collector 31, 5 is a negative electrode obtained by joining the negative electrode active material layer 52 to the negative electrode current collector 51, 4 is disposed between the positive electrode 3 and the negative electrode 5 and contains lithium ions It is a separator that holds non-aqueous electrolyte. 6 denotes a positive electrode active material layer 3 2 and a negative electrode active material layer 5 2 An adhesive resin portion that is partially arranged like a point, a line, or a grid between the surfaces facing the surface 4 and joins each active material layer 32, 52 to the separation 4 is there. Reference numeral 7 denotes a gap that connects the positive electrode active material layer 32 and the negative electrode active material layer 52 to the separator 4. The void 7, the separator 4, and the active material layers 32, 52 hold a non-aqueous electrolyte containing lithium ions. In this embodiment, the adhesive resin portion 6 and the void portion 7 are simultaneously formed between the positive and negative electrode active materials 32, 52 and the separator 4, so that the electrolyte is held inside the void 7. However, good ionic conductivity between the two electrodes can be ensured, and the ionic conduction resistance between the two electrodes can be reduced to the level of a conventional battery. Since the electrodes are electrically connected via a liquid electrolyte with low ionic conduction resistance, the amount of lithium ions flowing into and out of the active material layer inside the electrodes and the speed and movement of lithium ions to and from the opposite electrode The volume can be made comparable to that of a conventional lithium-ion secondary battery using an outer can. In addition, since the adhesiveness between the electrodes 3 and 5 and the separator 4 is ensured by the adhesive resin 6, the battery structure can be maintained without using an outer can. Therefore, the battery can be reduced in weight and thickness, and can be formed into an arbitrary form, and battery performance such as charge / discharge characteristics comparable to that of a conventional battery can be obtained without an outer can.

In addition, the area of the void 7 formed by the adhesive resin part 6 partially arranged is 30% of the total area of each opposing surface where the active material layers 32, 52 and the separator 4 oppose each other. %, Preferably 90%, and most preferably about 60%. If it is less than 30%, the electric connection between the electrode active material layers 32, 52 and the separator 4 becomes insufficient, and the ion conduction resistance between the electrodes 3, 5 increases, so that a sufficient battery It becomes difficult to obtain characteristics. If it exceeds 90%, the adhesive strength between the electrodes 3 and 5 and the separator 4 becomes insufficient, and peeling occurs. In addition, the depth of the void 7 formed between the active material layers 32, 52 and the separation layer 4, that is, the distance L between the active material layers 32, 52 and the separation layer 4, is determined as follows. of different but the ion conductivity, in the case of 1 0- ² S / cm extent that is usually used, 3 if 0〃M less, between the active material layer 3 2, 5 2 and separator one evening 4 Since the ionic conduction resistance of the battery becomes sufficiently small, and the battery can be used at a high load factor that is not inferior to batteries using conventional outer cans, it is desirable that the ion transport resistance be 30 zm or less. Further, by setting the depth L of the void portion 7 to 10 以下 1 or less, the diffusion of the reactive species can be facilitated and the ion conduction resistance can be further reduced, so that 10 / m It is more desirable to adjust the following. In addition, it is said that a diffusion layer of several meters exists on the surface of the active material 32, 52 where an electrode reaction occurs.By adjusting the depth L of the void 7 to less than this, Since the diffusion of lithium ions is considered to proceed most easily, it is most desirable to set the depth L of the void 7 to several 〃 m or less. -The lithium ion secondary battery configured as described above is manufactured, for example, by the following method. A step of applying the positive electrode active material layer 32 and the negative electrode active material layer 52 to the current collectors 31 and 51, respectively, at least one of the opposing surfaces of the positive electrode active material layer 32 and the separator 4 and the negative electrode active material As the adhesive resin 6 is partially applied to at least one of the opposing surfaces of the layer 52 and the separator, the respective surfaces of the positive electrode active material layer 32 and the negative electrode active material are coated on the respective surfaces of the separator 4. The opposing surfaces of the layers 52 are superimposed and pressurized while heating, and the adhesive resin 6 is thermally fused to bring the electrodes 3 and 5 into close contact with the separator 4. By doing so, a basic battery structure is manufactured.

In addition, for bonding between the electrode and the separator overnight, a battery in which a resin having a desired height is easily disposed at a desired position can easily be obtained by using a resin having an electronic insulating property which is solid at room temperature and melting by heating at the time of coating. Manufacturable. Such bonding Any resin can be used as long as it does not dissolve in the electrolyte solution and does not cause an electrochemical reaction inside the battery. Specifically, Nittite H-6825A (trade name: manufactured by Nitta Gelatin Co., Ltd.), Bondyne (trade name: manufactured by Sumitomo Chemical Co., Ltd.) and AK—1 (trade name: Kanebowenesushiichi Co., Ltd.) Thermoplastic resins such as those manufactured by Toshiba can be used.

The following methods can be used to apply the adhesive resin 6 locally and to apply a large amount of the adhesive resin to both surfaces of the separator 4 in a short time.

FIG. 2 is an explanatory view showing the melt printing method, in which (a) is viewed from above and (b) is viewed from the side. This is a coating method in which the molten resin 6 is brought into contact with a rotating roll 61 having a point-like depression 61a and transferred to a sheet (for example, a sheet-like separator 4).

FIG. 3 is an explanatory view showing a method of applying an adhesive resin using a rotating roll having fine holes on the surface, wherein (a) is viewed from above and (b) is viewed from the side. A molten adhesive resin is filled into the inside of the rotating roll 62 having the minute holes 62 on the surface, and pressure is applied to the inside of the rotating roll 62 by the pressurizer 63 to remove the small holes 62a from the small holes 62a. Let the adhesive resin flow out. At the same time, by rotating the entire rotating roll 62 while moving the separating material 4 supplied from the separating material roll, the adhesive resin 6 is applied to both surfaces of the separating material 4 in a dot-like manner.

Further, as shown in the explanatory view of FIG. 4, there is a method of applying an adhesive resin using a screen and a rotating roll in which holes are formed in dots or lines. Set up a billet-shaped screen 6 4 with holes 6 4 a in the vicinity of the surface of the separator material 4, and move the adhesive resin 6 from the adhesive resin dropping port 6 5. The adhesive resin is supplied by being dripped onto the screen 64 disposed above, and the supplied adhesive resin is rolled by the rotating rolls 66 to thereby reduce the screen. The adhesive resin 6 reflecting the shape of the hole 6 4 a of the resin 6 4 is transferred to the separation material 4. By arranging at least two of them on both surfaces of the separation material 4, the adhesive resin can be applied to both surfaces of the separation material 4 in a dot-like manner.

FIG. 5 is an explanatory view showing a method of applying an adhesive resin using a spray gun. After installing a screen-shaped screen 67 with holes in the form of dots, lines, or grids near the surface of the separation material 4, the molten adhesive resin was charged into the spray gun 68, Spray on Separee overnight material 4 through screen 67. As a result, the adhesive resin 6 adheres to the separation material 4 in a shape corresponding to the holes of the screen 67, for example, in a dot shape. At least one spray gun 6 8 is arranged on each side of the separation material 4 and the adhesive resin liquid is continuously sprayed while moving the separation material 4 so that the separation material 4 The adhesive resin 6 can be applied in a dot-like manner. Note that a net or the like may be used instead of the screen 67. In addition, as shown in the explanatory diagram of FIG. 6, at least one dispenser 69 filled with an adhesive resin liquid is placed on the separating material 4 and the adhesive melted as the separating material 4 moves. The adhesive resin 6 may be applied in a dot-like manner by intermittently dropping the adhesive resin liquid. (A) is viewed from above, and (b) is viewed from the side.

As the electrode active material used in the present invention, in the positive electrode 3, for example, an oxide of lithium and a transition metal such as cobalt, nickel, or manganese; a chalcogen compound containing lithium or a composite oxide thereof; Metal oxides, chalcogen compounds containing lithium, or composite oxides of these with a small amount of various elements added are used, and those obtained by adding graphite as an electron conductor to these substances are used. . In the negative electrode 5, graphite, graphitizable carbon, non-graphitizable carbon, polyacene, Preferably used are carbon compounds such as polyacetylene, and aromatic hydrocarbon compounds having an acene structure such as bilen and perylene, but are not limited to these, and occlude and release lithium ions necessary for battery operation. Any other substance that can be used can be used. In addition, these substances are used in the form of particles, and a particle diameter of 0.3 zm to 20 Aim can be used, and particularly preferably 0.3 // m to 5 zm. . Carbon fibers can also be used as the negative electrode active material 52.

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

The current collectors 31 and 51 can be used as long as the metal is stable inside the battery. However, as the material, aluminum is preferably used for the positive electrode 3 and copper is preferably used for the negative electrode 5. The current collectors 31 and 51 may be in the form of foil, mesh, expanded metal or the like, but foil is preferably used in order to obtain electrode smoothness.

The separator 4 is made of any material such as a porous film made of an electronic insulating material, a nonwoven fabric, a net, and the like, as long as the material has sufficient strength to adhere to the electrodes 3 and 5. Anything can be used. In particular, a single-layer porous film of polyethylene or polypyrene and a multi-layered porous film thereof are preferable from the viewpoint of adhesion and safety.

As the liquid electrolyte used for the electrolyte used as the ion conductor, a non-aqueous liquid electrolyte containing lithium ions used in conventional batteries can be used. Specifically, esters such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and getyl carbonate are used as solvents for the liquid electrolyte. Aqueous solvents: A single solution of ether solvents such as dimethoxetane, diethoxetane, getyl ether, and dimethyl ether, and a mixed solution of two or more of the above-mentioned solvents of the same system or different types of solvents can be used. is there. The electrolyte salt used in the liquid _{electrolyte, L iPF 6, L iA sF} 6, L i C 10 4, L iBF 4, L i CF 3 S_〇 _{_{3, L iN (CF 3 S0}} 2) 2, L i C _{_{_{(CF 3 S0 2) 3,}}} L iN (C 2 F 5 S0 2) 2 , or the like can be used.

In the above embodiment, a single-layer electrode type battery has been described. However, the present invention is also applicable to a stacked electrode type battery having a plurality of layers of an electrode stack. A lithium ion secondary battery with a large battery capacity can be obtained. For example, as shown in FIG. 8, a structure having a plurality of electrode laminates in which positive electrodes 3 and negative electrodes 5 are alternately arranged between a plurality of separated separators 4, FIGS. 9 and 10 In addition to the structure having multiple layers of electrode laminates, the cathode 3 and the anode 5 are alternately arranged between the strip-shaped separators 4 as shown in Fig. A stacked electrode type battery is obtained by a structure having a plurality of layers of an electrode stack in which the positive electrode 3 and the negative electrode 5 are alternately arranged between the strip-shaped separators 4. The manufacturing method of the stacked electrode type battery shown in FIGS. 8, 9 and 10 will be described in detail in the following examples.

Hereinafter, the present invention will be described with reference to Examples, but it should be understood that the present invention is not limited by these.

Example 1.

This embodiment is a method for manufacturing a lithium ion secondary battery having the single-layer electrode type battery shown in FIG.

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

87% by weight Li CoO, 8% by weight graphite powder, Pinda resin 9/1

13 A 5% by weight positive electrode active material paste made of polyvinylidene fluoride (produced by Kureha Chemical Industry Co., Ltd., trade name: KF110) is coated on a 20-zm-thick aluminum foil as a current collector. The coating was applied to a thickness of about 100 μm using a Doc Yuichi blade method to produce a positive electrode.

After the positive electrode 3 was immersed in the electrolytic solution, the peel strength between the positive electrode active material layer portion and the positive electrode current collector was measured, and a value of 20 to 25 / cm was shown. Next, fabrication of the negative electrode will be described.

Negative electrode with Mesophase Microbeads Carbon (manufactured by Osaka Gas Co., Ltd.) adjusted to 95% by weight, and polyvinylidene fluoride (manufactured by Kureha Chemical Industry Co., Ltd., trade name: KF110) adjusted to 5% by weight as a binder. The active material base was applied to a thickness of about 100 / m by a doctor blade method on a copper foil having a thickness of 12 / m as a current collector, to produce a negative electrode. After the negative electrode 5 was immersed in the electrolytic solution, the peel strength between the negative electrode active material layer portion and the negative electrode current collector was measured, and a value of 10 to 50 gf / cm was shown. The production of the electrode laminate will be described.

A roll of 12 cm wide, 25 m thick porous polypropylene sheet (made by Hoechst Celanese Co., Ltd., trade name: SERGADE # 2400) used as Separete 4 H-6285 (product number: Nitta Gelatin Co., Ltd.) as an adhesive resin 6 on both surfaces thereof was melt-printed (the molten resin was rolled with a roll 61 having dot-shaped depressions 6 la). (Method of transferring to a wiped sheet). At the time of application, the thickness of the adhesive resin 6 was about 35 m, and the application area was 60% of the entire Separet. The coating pattern of the resin 6 can be changed by changing the shape of the recess 61 a of the opening 61. Further, the coating area can be changed by changing the number of the grooves 61 a of the take-up roll 61.

Next, after the temperature is once lowered to room temperature, the positive electrode 3 and the negative electrode 5 And placed in close contact with each other. Thereafter, the adhesive resin 6 was sandwiched between heating rolls whose surface temperature was set at 70 ° C., and the adhesive resin 6 was re-melted to fuse the resin between the electrodes 3 and 5 and the separator 4 to produce an electrode laminate. The thickness of the adhesive resin portion 6 calculated from the total thickness of the fused electrode laminate, that is, the distance between the separator 4 and the active material layers 32, 52 was about 30 m. The distance between the separator 4 and the active material layers 32, 52 depends on the thickness or amount of the adhesive resin 6 at the time of application, and the temperature of the heating roll when the electrodes 3, 5 and the separator 4 are brought into close contact. It can be controlled by adjustment or the like.

Subsequently, the electrode laminate was cut into a length of 10 cm, and current collectors were welded to the current collectors 31 and 51, respectively. Thereafter, the internal electrode stack, the ethylene carbonate Jechiru as a solvent, an electrolytic solution was injected to the L i PF ₆ as a solute. At this stage, when the peel strengths of the positive electrode active material layer 32 and the separator 4 and the negative electrode active material layer 52 and the separator 4 were measured, the peel strength was 30 gf / cm or more and 20 gf / cm, respectively. cm or more. After the injection of the electrolytic solution, the electrode laminate other than the current collector was packed with an aluminum laminated film, heat-sealed and sealed to complete the lithium ion secondary battery.

FIG. 7 is a schematic cross-sectional view showing the lithium ion secondary battery manufactured as described above. In the figure, 20 is an electrode laminate, 22 is an aluminum laminate film of the exterior, and 33 and 53 are current collecting tabs. The electrode laminate 20 includes a positive electrode 3, a separator 4, and a negative electrode 5. The adhesive resin 6 is located between the positive electrode 3 and the separator 4 and between the negative electrode 5 and the separator 4, and partially joins the positive electrode 3 and the negative electrode 5 to the separator 4. An electrolyte is held in the gap 7 between the positive electrode 3 and the separator 4 and between the anode 5 and the separator 4, in the electrode active materials 32 and 52, and in the separator 4. Cover between the positive electrode 3 and the negative electrode 5 and the separator 4 with adhesive resin 6 The electrolyte containing lithium ions is retained inside the voids 7 that are formed at the portion where the adhesive resin 6 is not applied without being exhausted, so that the internal resistance between the positive electrode 3 and the negative electrode 5 increases. Suppressed, good ionic conductivity is ensured, and the adhesion between the electrodes 3, 5 and Separation 4 is maintained by the adhesive resin 6, so no external pressurization is required. A lithium-ion secondary battery that is thin, lightweight, and does not require a can and has excellent charge / discharge characteristics has been obtained.

Example 2.

Bondine (trade name: manufactured by Sumitomo Chemical Co., Ltd.) or AK 1 (trade name: manufactured by Kanebo Wenussichi Co., Ltd.) was used as the material for the adhesive resin, and the other materials were the same as in Example 1. And the electrode laminated body was produced by the manufacturing method. Also in this case, it was possible to adhere the electrode and the separator overnight with a gap. Thereafter, the same electrolytic solution as in Example 1 was injected into the electrode laminate, and the peel strength was examined. The same result as in Example 1 was obtained. After the injection of the electrolytic solution, the electrode laminate is packed with an aluminum laminate film, heat-sealed, and sealed to form a lithium ion secondary battery that is thin, light, and has excellent charge / discharge characteristics, as in Example 1. A battery was obtained.

Example 3.

After preparing the positive electrode 3 and the negative electrode 5 using the same materials and methods as described in Example 1, a porous polypropylene sheet having a width of 12 cm and a thickness of 25 m, which is bundled in a roll shape as a separation material 4. (Made by Hoechst Celanese Co., Ltd., trade name: Celgard # 240), and on both sides of it, H—6285 (product number: Nitta Gelatin Co., Ltd.) as adhesive resin 6 It was applied dotwise by the melt printing method. By making the recess of the roll shallower than in the case of Example 1, the thickness of the adhesive resin 6 at the time of application was about 15 μm. Next, once the temperature is lowered to room temperature, the positive electrode 3 and the negative electrode 5 are sandwiched between the separators 4. And placed in close contact with each other. Thereafter, it was sandwiched between heating rolls whose surface temperature was set to 70 ° C., and the resin 6 was re-melted to fuse between the electrodes 3, 5 and the separator 4 to prepare an electrode laminate. The thickness of the adhesive resin portion 6 calculated from the total thickness of the fused electrode laminate was 10 μm or less. Followed by cutting the electrode stack to the length 1 0 cm, followed the L i PF ₆ was ethylene carbonate Jechiru a solvent in the electrode laminate portion injected electrolytic solution as a solute. At this stage, the peel strengths of the positive electrode active material 32 and Separation 4 and the negative electrode active material 52 and Separation 4 were measured, and the strength was 30 g / cm or more, respectively. Met. After the injection of the electrolyte, the electrode laminate was packed with an aluminum laminate film, heat-sealed, and sealed to complete a thin lithium-ion secondary battery.

In the electrode laminate according to the third embodiment, the distance between the electrode active materials 32, 52 and the separator 4 is 10 / m or less, so that the diffusion of the reactive species generated by the electrode reaction is more easily performed. As the ionic conduction resistance at the interface between the active material and the separator can be reduced, thin lithium-ion secondary batteries using this can be used at a high load factor that is not inferior to batteries using conventional outer cans. Became possible.

Example 4.

After preparing the positive electrode 3 and the negative electrode 5 using the same materials and method as described in Example 1, a porous polypropylene having a width of 12 cm and a thickness of 25 / m, which is bundled in a roll as a separator material 6. Take out the sheet (manufactured by Hoechst Celanese Co., Ltd., trade name: Celgard # 2400), and on both sides of the sheet, use H-6825 as the adhesive resin 6 (product number: Nitta Gelatin Co., Ltd.) Was applied dotwise by a melt printing method. Adhesive resin 6 is applied on the separator by reducing the number of roll dents compared to Example 1. The area of the site was adjusted to 40% of the whole. Next, the temperature was once lowered to room temperature, and the positive electrode 3 and the negative electrode 5 were arranged so as to face each other with the separator 4 interposed therebetween, and were brought into close contact with each other. Thereafter, the resin was sandwiched between heating rolls whose surface temperature was set to 70 ° C., and the resin 6 was re-melted to fuse between the electrodes 3 and 5 and the separator 4 to prepare an electrode laminate.

Followed by cutting the electrode stack to the length 1 0 cm, followed the L i PF ₆ was ethylene carbonate Jechiru a solvent in the electrode laminate portion injected electrolytic solution as a solute. At this stage, when the peel strengths of the positive electrode active material 32 and Separation 4 and the negative electrode active material 52 and Separation 4 were measured, the peel strengths were 30 / cm or more and 20 gf / cm or more, respectively. there were. The electrode stack other than the current collector after the injection of the electrolyte was packed with an aluminum laminate film, heat-sealed, and sealed to complete a thin lithium-ion secondary battery.

In the electrode laminate of this example, the area of the adhesive resin applied to the separator 4 was 40% of the total area, so that the ion conduction resistance at the interface between the active material and the separator was reduced. Therefore, a thin lithium-ion rechargeable battery using this can be used at a high load factor that is not inferior to a battery using a conventional outer can.

Comparative Example 1.

After preparing the positive electrode 3 and the negative electrode 5 using the same materials and methods as described in Example 1, a porous polypropylene sheet having a width of 12 cm and a thickness of 25 zm bundled in a roll as a separation material 4 is provided. (Made by Hoechst Celanese Co., Ltd., trade name: Celgard # 240), and on both sides of it, H—6285 (product number: Nitta Gelatin Co., Ltd.) as adhesive resin 6 It was applied dotwise by the melt printing method. By further reducing the number of depressions in the roll than in Example 4, the adhesive resin 6 was applied onto the separation 4. The area of the part that has been adjusted has been adjusted to 20% of the total. Next, the temperature was once lowered to room temperature, and the positive electrode 3 and the negative electrode 5 were arranged so as to face each other with the separator 4 interposed therebetween, and were brought into close contact with each other. Thereafter, the resin was sandwiched between heating rolls whose surface temperature was set at 70 ° C., and the resin 6 was re-melted to fuse between the electrodes 3, 5 and the separator 4, thereby producing an electrode laminate.

Followed by cutting the electrode stack to the length 10 cm, after which the L iPF ₆ was ethylene carbonate Jechiru a solvent in the electrode laminate portion injected electrolytic solution as a solute. At this stage, the peel strengths of the positive electrode active material 32 and Separation 4 and the negative electrode active material 52 and Separation 4 were both measured to be 5 / cm or less. At this strength, separation between the electrodes 3 and 5 and Separation 4 occurred during use when the battery was used.

Example 5.

This embodiment is a method of manufacturing a lithium-on secondary battery having the flat-plate laminated battery body shown in FIG. In FIG. 8, the resin portion 6 and the void portion 7 are shown without distinction.

First, the fabrication of the positive electrode 3 will be described.

A positive electrode active material paste prepared by dispersing 87 parts by weight of LiCoO ₂ , 8 parts by weight of graphite powder, and 5 parts by weight of polyvinylidene vinylidene in N-methylpyrrolidone (abbreviated as NMP) was used to prepare a positive electrode active material paste. The active material thin film 32 was formed by applying a thickness of 300 / m by the Yuichi blade method. An aluminum foil with a thickness of 30 m to be the cathode current collector 31 was placed on the upper part, and a cathode active material base adjusted to a thickness of 300 m by the Doc Yuichi blade method was applied on the aluminum foil again. . This was left in a dryer at 60 ° C for 60 minutes to make it semi-dry. Positive electrode 3 was produced by lightly rolling the produced laminate using a rotating roll with the gap between the rolls adjusted to 550Π1 and bringing the laminate into close contact. After the positive electrode 3 was immersed in the electrolytic solution, the peel strength between the positive electrode active material layer portion and the positive electrode current collector was measured, and a value of 20 to 25 gf / cm was shown. Next, the fabrication of the negative electrode 5 will be described.

Negative active material paste prepared by dispersing 95 parts by weight of mesophase microbead carbon (manufactured by Osaka Gas Co., Ltd.) and 5 parts by weight of polyvinylidene fluoride in NMP was thickened by the Doc Yuichi blade method. The active material thin film 52 was formed by applying the composition to a thickness of 30 O / m. A copper foil having a thickness of 20 / m to be a negative electrode current collector 51 is placed on the upper part, and a negative electrode active material base adjusted to a thickness of 300 / m again by the Doc Yuichi blade method is further placed on the copper foil. Was applied. This was left in a dryer at 60 ° C for 60 minutes to make it semi-dry. The produced laminate was lightly rolled using a rotating roll with the gap between the rolls adjusted to 550 zm, and the laminate was brought into close contact to produce a negative electrode 5.

After the negative electrode 5 was immersed in the electrolytic solution, the peel strength between the negative electrode active material layer portion and the negative electrode current collector was measured, and a value of 10 to 55 gf / cm was shown. The production of the electrode laminate will be described.

Separation material 4 A roll of a porous polypropylene sheet (Hexist Celanese Co., Ltd., trade name: Celgard # 2400) with a width of 12 cm and a thickness of 25 zm, which is bundled in a roll shape as a material 4 Each of them was taken out, and H-6285 (product number: Nitta Gelatin Co., Ltd.) was applied to one surface of each side in a dot-like manner by a melt print method. The thickness and coating area of the resin 6 were the same as in Example 1. Next, the temperature of the adhesive resin 6 was once lowered to room temperature, and one negative electrode 5 (or positive electrode) was placed so as to be opposed to and sandwiched between two sheets of separator 4. Thereafter, it was sandwiched between heating rolls whose surface temperature was set at 70 ° C., and the resin 6 was re-melted to fuse between the electrodes 3 and 5 and Separee overnight 4. Next, the resin 6 is applied to one of the four surfaces of the negative electrode 5 with the separator 5 cut into a predetermined size using a melt printing method. The positive electrode 3 (or negative electrode) punched into a predetermined size was brought into close contact with it, and heated with a jar to heat-bond. Next, a resin 6 was applied to one of the four surfaces of the separator 5 with the new negative electrode 5 with a separate separator, adhered to the other surface of the previously bonded positive electrode 3, and thermally fused. This process was repeated a predetermined number of times to obtain a flat-plate laminated battery body as shown in FIG.

The positive electrode and negative electrode current collectors 31 and 51 of this flat plate-shaped laminated battery body were spot-welded to the positive and negative electrodes of the positive and negative electrodes, respectively. Electrically connected in parallel.

Subsequently, the L i PF ₆ was ethylene carbonate Jechiru the solvent within electrode stack the electrolyte solution was injected to the solute. After the electrolyte was injected, the battery body was packed with an aluminum laminate film, heat-sealed, and sealed to complete a thin lithium-ion secondary battery with stacked electrodes.

Example 6

This embodiment is a method for manufacturing a lithium ion secondary battery having the flat-plate-shaped battery structure shown in FIG. In FIG. 9, the resin portion 6 and the void portion 7 are shown without distinction.

After preparing the positive electrode 3 and the negative electrode 5 using the same materials and methods as described in Example 5, a porous polypropylene sheet having a width of 12 cm and a thickness of 25 m, which is bundled in a roll shape as a separation material 4. Take out two (Hegist Celanese Co., Ltd., product name: Celgard # 2400), and use H—6825 as an adhesive resin 6 on one side (product number: Nitta Gelatin Co., Ltd.) ) Was applied dotwise by melt printing. The thickness and coating area of the resin 6 were the same as in Example 1. Next, the temperature of the adhesive resin 6 was once lowered to room temperature, and one positive electrode 3 (or negative electrode) was arranged so as to be opposed to each other while being sandwiched between two separate separators 4. After that, it is sandwiched between heating rolls whose surface temperature is set at 70 ° C, resin 6 is re-melted, and the negative electrode 5 (or positive electrode) and the separator are separated. 4 was fused.

Next, apply resin 6 to one side of the positive electrode 3 (or negative electrode) with a strip-shaped separator, and apply a resin 6 to the 4th surface, bend one end of the positive electrode 3 (or negative electrode) with the separator separately, Negative electrode 5 (or positive electrode), which had been cut to the size of, was sandwiched. Subsequently, the negative electrode 5 (or the positive electrode) and the positive electrode 3 (or the negative electrode) with separation were overlapped, and the whole was heated and fused with a roll. After that, on the positive electrode 3 (or the negative electrode) with the separator, the resin 6 was applied on the opposite side of the surface on which the resin 6 was previously applied, followed by the bow I and then wound on an ellipse.

The wound battery body on the ellipse is heated and fused by a roll, and the positive electrode 3 and the negative electrode 5 are adhered to the separator 4 to obtain a flat-plate wound laminated battery body as shown in FIG. Was.

The positive and negative electrode current collectors 31 and 51 of the flat laminated battery body were spot-welded to the positive and negative electrodes of the current collecting tabs connected to the respective ends of the current collectors 31 and 51, so that the laminated battery body was electrically connected. Were connected in parallel.

Subsequently, the L i PF ₆ was ethylene carbonate Jechiru the solvent within electrode stack the electrolyte solution was injected to the solute. After injecting the electrolyte solution, the battery body was packed with an aluminum film, heat-sealed, and sealed to complete a thin lithium ion secondary battery in which electrodes were wound and laminated. Embodiment 7.

In Example 6 above, an example was shown in which the separator 4 was wound up. However, the strip-shaped separator 4 in which the positive electrode 3 (or the negative electrode) was joined was folded, and the negative electrode 5 (or the positive electrode) was attached to the separator. The process of folding overnight 4 may be repeated to obtain a flat-type foldable laminated battery body.

Example 8

This embodiment is directed to a lithium battery having the flat wound type laminated structure battery body shown in FIG. This is a method for manufacturing a pumion secondary battery, which is different from Example 6 above in that each electrode and separator are simultaneously wound. In FIG. 10, the resin portion 6 and the void portion 7 are shown without distinction.

After preparing the positive electrode 3 and the negative electrode 5 by using the same materials and the same method as described in Example 5, a width of 12 cm and a thickness bundled in a roll as a separation material 4 were prepared.

Take out two 25 m porous polypropylene sheets (made by Hoechst Celanese Co., Ltd., product name: Celgard # 240), each of which has an adhesive resin 6 on one side as H—68 25 (product No .: Nitta Gelatin Co., Ltd.) was applied dot-wise by melt printing. The thickness and coating area of the resin 6 were the same as in Example 1. Next, the temperature of the resin 6 was once lowered to room temperature, and one positive electrode 3 (or negative electrode) was placed so as to be opposed to and sandwiched between two sheets of the separator 4 so as to be in close contact with each other. After that, it is sandwiched between heating rolls whose surface temperature is set at 70 ° C, resin 6 is re-melted, and the positive electrode 3 (or the negative electrode) is fused between the positive electrode 3 (or negative electrode 4) and the positive electrode 3 (positive electrode 3). (Or negative electrode) to obtain positive electrode 3 (or negative electrode) with separate separation fused to both sides. Positive electrode with this separation

On both sides of Separation 3 on both sides of 3 (or the negative electrode), resin coating 6 was applied by melt printing.

Next, the strip-shaped negative electrode 5 (or the positive electrode) was arranged so as to protrude by a certain amount on one side of the positive electrode 3 (or the negative electrode) with a separation. Bend the protruding negative electrode 5 (or positive electrode) and wrap it around the positive electrode 3 (or negative electrode) with the separator, and then bond the positive electrode 3 (or negative electrode) with the separator, and then fold the negative electrode 5 (or negative electrode). (Or positive electrode). After repeating this operation, the whole was fused with a heating roll to obtain a wound laminated battery body as shown in FIG.

The positive and negative electrode current collectors 31 and 51 of this flat laminated battery body were spot-welded to the positive and negative electrodes of the positive and negative electrodes, respectively. As a result, the stacked battery bodies were electrically connected in parallel.

Subsequently, the inside electrode stack was carbonated Echiren and carbonate Jechiru solvent L i PF _s an electrolytic solution was injected to the solute. After the electrolyte was injected, the battery body was packed with an aluminum laminate film, heat-sealed, and sealed to complete a thin lithium-ion secondary battery having a rolled-up laminated battery body.

In each of the above embodiments, the case where the adhesive resin 6 is applied to the separator 4 is described. However, the active material layers 32 and 52 may be applied. Both the material layers 32 and 52 may be applied. 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. 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 between the positive electrode active material layer and the negative electrode active material layer The bonding is partially arranged between each of the active material layers and the separation layer so as to form a gap communicating between each of the active material layers and the separation layer. A lithium ion secondary battery comprising: an electrode laminate having a conductive resin; and an electrolyte containing lithium ions in each of the space, the separator, and each active material layer.

2. The lithium ion according to claim 1, wherein an area of the void portion is 30% to 90% of a total area of each opposing surface of each active material layer and the separator. Rechargeable battery.

3. The lithium ion secondary battery according to claim 1, wherein a distance between each active material layer and the separator is 30 zm or less.

4. The lithium ion secondary battery according to claim 1, wherein an electronically insulating resin that is solid at room temperature is used as the adhesive resin.

5. The lithium ion secondary battery according to claim 1, comprising a plurality of electrode laminates.

6. The method according to claim 5, 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 secondary battery.

7. The lithium ion according to claim 5, wherein the plurality of layers of the electrode laminate are formed by alternately arranging the positive electrode and the negative electrode during the separated separation. Rechargeable battery.

8. The multiple layers of the electrode stack consist of a positive electrode and a negative electrode The lithium ion secondary battery according to claim 5, wherein the lithium ion secondary battery is formed by alternately arranging the lithium ion secondary batteries.