JP4297711B2 - Electrochemical element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrochemical device, and more particularly to reducing the possibility of a short circuit in an electrode plate group of a secondary battery having a high energy density.
[0002]
[Prior art]
As electronic and electrical devices become smaller and lighter, there is an increasing demand for smaller and lighter electrochemical devices such as secondary batteries. The electrode plate group of the secondary battery includes a stacked type and a wound type. The laminated electrode plate group is obtained by alternately laminating positive electrodes and negative electrodes via separators. The wound electrode plate group is obtained by winding a long positive electrode and a negative electrode through a separator. In order to take out electricity from these electrode plate groups without causing a short circuit, a current collecting tab and a current collecting lead are required. However, there is a concern that the current collecting tab or the current collecting lead may prevent a uniform electrode reaction on the electrode surface or cause an internal short circuit when a metal burr larger than usual occurs on the cut surface of the lead. There is also a drawback that the structure of the electrode plate group becomes non-uniform by interposing the current collecting tab or the current collecting lead between the electrode plates.
[0003]
Therefore, the positive electrode protrudes from one of the side surfaces of the electrode plate group, the negative electrode protrudes from the side surface opposite to the side surface, and electricity can be directly taken out from each side surface without using the current collecting tab or the current collecting lead. Proposed. For example, in a battery having a stacked electrode plate group, a technique has been proposed in which a protruded electrode plate of the same polarity is integrally joined using a predetermined metal member (see, for example, Patent Document 1). In addition, in a battery having a wound-type electrode plate group, a technique has been proposed in which a protruding core member of the same polarity and a plate-like current collector plate are joined (for example, see Patent Document 2). .
[0004]
[Patent Document 1]
JP 2001-126707 A
[Patent Document 2]
JP 2000-294222 A
[0005]
[Problems to be solved by the invention]
However, the conventional current collecting structure has a problem that it is difficult to reliably prevent a short circuit on the side surface of the electrode plate group in which the end surfaces of the positive electrode and the negative electrode are alternately arranged. It is possible to prevent short circuit to some extent by interposing a separator having a larger area than either of the positive electrode and the negative electrode between the electrode plates. However, since the separator becomes large, the volume efficiency becomes low and the high capacity electrode It becomes difficult to obtain a group of plates. In addition, when the positive electrode protrudes from one of the side surfaces of the electrode plate group and the negative electrode protrudes from the side surface opposite to the side surface, the electrode plate group must be manufactured one by one, and the electrode plate group manufacturing process Becomes complicated. That is, there is also a problem that a plurality of electrode plate groups cannot be manufactured simultaneously. In addition, since both the positive electrode and the negative electrode are always exposed on the side surface of the conventional electrode plate group, it is impossible to provide a current collecting terminal by metal spraying, and thus the terminal structure is limited. There is also.
[0006]
[Means for Solving the Problems]
The present invention has been made in view of the above situation. ADVANTAGE OF THE INVENTION According to this invention, the possibility of a short circuit is very small, the reliability is high, and the electrochemical element which has a high electrical capacitance can be provided. Since the electrochemical device of the present invention has a simple structure, a plurality of electrochemical devices can be efficiently produced at the same time.
[0007]
That is, the present invention provides an electrode group comprising (a) at least one first electrode, (b) at least one second electrode, and (c) a separator interposed between the first electrode and the second electrode. The first electrode (a) includes a first current collector sheet and at least one first electrode mixture layer carried thereon, and the second electrode (b) includes: It comprises a second current collector sheet and at least one second electrode mixture layer carried thereon, each electrode mixture layer having an end covered with an insulating material, and the insulating material is a resin The present invention relates to an electrochemical element which is at least one selected from the group consisting of a coating film and a resin tape.
[0008]
  In the first side surface of the electrode plate group, the first current collector sheet and the first terminal are connected. In the second side surface of the electrode plate group, the second current collector sheet and the second terminal are connected. Are connected, the end portion of the first electrode mixture layer covered with the insulating material is disposed on the second side surface, and is covered with the insulating material of the second electrode mixture layer. The end portion is disposed on the first side surface.The
[0009]
  The first current collector sheet and the second current collector sheet each have a conductive portion and an insulating portion.ShiThe conductive portion of the first current collector sheet and the conductive portion of the second current collector sheet are connected to the first terminal and the second terminal, respectively, and the first electrode mixture layer and the second electrode mixture are connected to each other. The end portions of the agent layer covered with the insulating material are adjacent to the insulating portion of the first current collector sheet and the insulating portion of the second current collector sheet, respectively.The
[0010]
In addition to the first side surface and the second side surface, the electrode plate group may have a side surface on which an insulating part of the first current collector sheet and / or an insulating part of the second current collector sheet are arranged. .
The first terminal and the second terminal are preferably disposed on opposite sides of the electrode plate group.
The electrode plate group may have a side surface on which an insulating material is disposed in addition to the first side surface and the second side surface.
[0011]
The insulating material is preferably at least one selected from the group consisting of a resin coating film and a resin tape.
The resin coating film can be formed by applying a solution or dispersion containing an insulating resin to the end of the electrode mixture layer and drying.
The insulating resin contained in the solution or the dispersion includes polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and a copolymer comprising at least one of these, a polymer alloy, or a polymer blend. It is preferable to use at least one selected from
[0012]
The resin coating film can be formed by applying a solution or dispersion containing a polymerizable compound to the end of the electrode mixture layer and polymerizing the polymerizable compound. The polymerizable compound is preferably polymerized by at least one means selected from the group consisting of heat, ultraviolet rays and electron beams.
The polymerizable compound preferably has at least one functional group selected from the group consisting of an acrylate group and a methacrylate group.
[0013]
The resin tape can be made of an insulating base material and an insulating adhesive carried on the insulating base material.
The insulating substrate is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyimide, aramid resin and a copolymer containing at least one of these, a polymer alloy, or a polymer blend. It is preferable to become.
As the insulating adhesive, for example, an acrylic resin or a butyl rubber resin can be used.
[0014]
  The present invention is also an electrochemical element having an electrode plate group in which a plurality of first electrodes and a plurality of second electrodes are alternately stacked via separators, wherein the plurality of first electrodes includes a first assembly. An electric sheet and an at least one first electrode mixture layer carried on the electric sheet, wherein the plurality of second electrodes comprise a second current collector sheet and at least one second electrode mixture layer carried thereon. And each of the electrode mixture layers relates to a laminated electrochemical element having an end portion covered with an insulating material.In the first side surface of the electrode plate group, the first current collector sheet and the first terminal are connected. In the second side surface of the electrode plate group, the second current collector sheet and the second terminal are connected. Are connected, and an end portion of the first electrode mixture layer covered with the insulating material is disposed on the second side surface and covered with the insulating material of the second electrode mixture layer An end portion is disposed on the first side surface. The first current collector sheet and the second current collector sheet each have a conductive part and an insulating part, and the conductive part of the first current collector sheet and the conductive part of the second current collector sheet are respectively The end portions connected to the first terminal and the second terminal and covered with the insulating material of the first electrode mixture layer and the second electrode mixture layer are respectively insulated from the first current collector sheet. And the insulating portion of the second current collector sheet.
[0015]
  The present invention is also an electrochemical element having an electrode plate group in which a first electrode and a second electrode are wound through a separator, wherein the first electrode is supported by the first current collector sheet and the first current collector sheet. The second electrode is composed of a second current collector sheet and at least one second electrode mixture layer carried thereon, and each of the electrode mixture layers Relates to a wound electrochemical device having an end covered with an insulating material.In the first side surface of the electrode plate group, the first current collector sheet and the first terminal are connected. In the second side surface of the electrode plate group, the second current collector sheet and the second terminal are connected. Are connected, and an end portion of the first electrode mixture layer covered with the insulating material is disposed on the second side surface and covered with the insulating material of the second electrode mixture layer An end portion is disposed on the first side surface. The first current collector sheet and the second current collector sheet each have a conductive part and an insulating part, and the conductive part of the first current collector sheet and the conductive part of the second current collector sheet are respectively The end portions connected to the first terminal and the second terminal and covered with the insulating material of the first electrode mixture layer and the second electrode mixture layer are respectively insulated from the first current collector sheet. And the insulating portion of the second current collector sheet.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
In the present embodiment, an example of an electrochemical element having a stacked electrode group will be described. In FIG. 1, the longitudinal cross-sectional view of the laminated type electrode group of the electrochemical element which concerns on this Embodiment is shown. FIG. 2 is a cross-sectional view of the electrode plate group taken along the line aa.
The electrode plate group 10 includes a plurality of first electrodes 15a and a plurality of second electrodes 15b that are alternately stacked, and a separator 16 is interposed between the first electrode 15a and the second electrode 15b.
[0017]
The first electrode 15a includes a first current collector sheet 13a and two first electrode mixture layers 14a. The first current collector sheet 13a has a resin sheet 11a and a predetermined shape pattern provided on both surfaces thereof. It consists of a conductive layer 12a. That is, the first current collector sheet 13a has a conductive portion and an insulating portion according to the shape pattern of the conductive layer.
[0018]
In FIG. 1, on each side of the electrode plate group 10, the end of each current collector sheet and the end of the separator are arranged almost flush with each other. The end portions of the current collector sheets and the end portions of the separators are substantially flush with each other. In the electrode group 10, since the end portions of the separator and the electrode plate do not protrude from the side surfaces, the volume efficiency is high and a high capacity can be obtained. Such an electrode plate group has a simple and well-structured structure, so that it is easy to ensure reliability. Moreover, since many electrode plate groups can be manufactured at the same time as described later, the manufacturing cost can be reduced.
[0019]
1 and 2, a conductive layer is provided on the entire surface of the first current collector sheet except for the end portions 11x, 11x ′ and 11x ″. Since the surface of the conductive layer becomes a conductive portion, the conductive layer is formed on the conductive layer. The first electrode mixture layer is provided.The end portions 11x, 11x ′, and 11x ″ of the sheet that does not have the conductive layer are insulating portions. The exposed portion of the conductive layer used for current collection remains at the end portion 12x of the sheet located on the opposite side of the end portion 11x.
[0020]
The electrode plate group 10 includes two types of second electrodes 15b and 15b '. The internal second electrode 15b sandwiched between the two first electrodes 15a has the same structure as the first electrode 15a except that the arrangement in the electrode plate group is reversed. That is, the internal second electrode 15b includes a second current collector sheet 13b and two second electrode mixture layers 14b, and the second current collector sheet 13b is a resin sheet 11b and a predetermined provided on both surfaces thereof. The conductive layer 12b has the following shape pattern. The outermost two second electrodes 15b 'have the same structure as the inner second electrode, except that the conductive layer 12b and the second electrode mixture layer 14b are provided on one side, not on both sides of the resin sheet 11b. Have
[0021]
A conductive layer is provided on the entire surface excluding the end portions 11y, 11y ′ and 11y ″ of the second current collector sheet. Since the surface of the conductive layer becomes a conductive portion, the second electrode mixture layer is formed thereon. The end portions 11y, 11y ′ and 11y ″ of the sheet having no conductive layer are insulating portions. An exposed portion of the conductive layer used for current collection remains at the end 12y of the conductive layer located on the opposite side of the end 11y.
[0022]
The thickness of the resin sheet is, for example, 0.5 to 500 μm. Moreover, the thickness of a conductive layer is 0.01-100 micrometers, for example. The thickness of the first electrode mixture layer is, for example, 1 to 1000 μm. However, these thicknesses are not particularly limited.
A normal resin sheet having a flat surface may be used, and a perforated body, a lath body, a porous body, a net, a foam, a woven fabric, a non-woven fabric, or the like may be used. Moreover, the resin sheet which has an unevenness | corrugation on the surface can also be used.
[0023]
Examples of the resin sheet include olefin polymers such as polyethylene, polypropylene and polymethylpentene, ester polymers such as polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate and polyarylate, and thioethers such as polyphenylene sulfide. Polymers, aromatic vinyl polymers such as polystyrene, nitrogen-containing polymers such as polyimide and aramid resin, and fluoropolymers such as polytetrafluoroethylene and polyvinylidene fluoride can be used. These may be used singly or may be a copolymer, polymer alloy, polymer blend or the like combining two or more.
[0024]
As the conductive layer, an electronic conductor that does not cause a chemical change in the constructed battery can be used without any particular limitation. When the first electrode is a positive electrode, for example, stainless steel, aluminum, aluminum alloy, titanium, carbon and the like can be used, and aluminum, aluminum alloy and the like are particularly preferable. When the first electrode is a negative electrode, for example, stainless steel, nickel, copper, copper alloy, titanium, and the like can be used, and copper, copper alloy, and the like are particularly preferable.
[0025]
The method for forming the conductive layer is not particularly limited. For example, the conductive layer can be obtained by depositing a conductive material on the surface of the resin sheet. In order to form a vapor deposition film having a predetermined shape pattern, vapor deposition is performed after covering a resin sheet with a mask having openings having a predetermined shape.
[0026]
The exposed portion of the conductive layer of the first current collector sheet is disposed on the first side surface (left side in FIG. 1) of the electrode plate group 10, and the opposite insulating portion is the second side surface of the electrode plate group 10 ( The right side of FIG. In FIG. 1, the first side surface and the second side surface are located on opposite sides of the electrode plate group, but their arrangement is not particularly limited. On the other hand, the exposed portion of the conductive layer of the second current collector sheet is disposed on the second side surface of the electrode plate group 10, and the insulating portion on the opposite side is disposed on the first side surface of the electrode plate group 10. Yes.
[0027]
Thus, since the 1st electrode and 2nd electrode which have the same structure are arrange | positioned in the mutually reverse direction, the exposed part of the conductive layer of a 1st electrical power collector sheet | seat is a 2nd electrical power collector sheet | seat Adjacent to the insulation. The exposed portion of the conductive layer of the second current collector sheet is adjacent to the insulating portion of the first current collector sheet. With such an arrangement, it is easy to obtain a high-capacity electrode plate group by connecting the exposed portions of the conductive layers of the plurality of first current collector sheets or second current collector sheets in parallel. The insulating part of the second current collector sheet adjacent to the exposed part of the conductive layer of the first current collector sheet and the insulating part of the first current collector sheet adjacent to the exposed part of the conductive layer of the second current collector sheet are: The width is preferably 0.001 mm or more, more preferably 0.1 mm or more.
[0028]
In the electrode plate group 10, the insulating portion of the first current collector sheet and the insulating portion of the second current collector sheet are flush with the third side surface (left side in FIG. 2) and the fourth side surface (right side in FIG. 2), respectively. It is arranged. According to such a structure, it is possible to prevent a short circuit between the first electrode and the second electrode without interposing a separator larger than the current collector sheet between the electrode plates.
[0029]
Since the insulating part of the second current collector sheet is arranged on the first side surface and the insulating part of the first current collector sheet is arranged on the second side surface, the first side surface and the second side surface are short-circuited. It is possible to prevent this. However, in order to reliably prevent a short circuit and obtain a highly reliable electrochemical element, the end portion of the second electrode mixture layer disposed on the first side surface is further covered with the first insulating material portion 18a, It is necessary to cover the edge part of the 1st electrode mixture layer distribute | arranged to the 2nd side surface with the 2nd insulating material part 18b. As shown in FIG. 1, it is also possible to cover the end portion of the first electrode mixture layer disposed on the first side surface and the end portion of the second electrode mixture layer disposed on the second side surface with the insulating material portion. However, this is not always necessary and it does not have to be covered. The thickness of the insulating material portion is not particularly limited, but is preferably 0.001 mm or more, and more preferably 0.01 mm or more.
[0030]
As shown in FIG. 3, the end portions of the electrode mixture layers arranged on the third side surface (left side in FIG. 3) and the fourth side surface (right side in FIG. 3) are respectively connected to the third insulating material portion 18c and the fourth insulating material portion 18d. It is also possible to cover with. According to such a structure, it is possible to more reliably prevent a short circuit.
[0031]
A resin coating film or a resin tape can be used for the insulating material portion.
The resin coating film can be formed by applying a solution or dispersion containing an insulating resin to the end portion of the electrode mixture layer and drying. Although the coating method is not particularly limited, for example, the solution or dispersion can be coated on the current collector sheet around the electrode mixture layer by screen printing, die coating, or the like. The solution or dispersion may be liquid or pasty, and their viscosity may be arbitrarily controlled.
[0032]
Insulating resins to be included in the solution or dispersion include ether resins such as polyethylene oxide, polypropylene oxide, polyacetal, polyphenylene ether, polyether ether ketone, and polyetherimide; acrylonitrile resins such as polyacrylonitrile, AS resin, and ABS resin A fluororesin such as polyvinylidene fluoride; an acrylic resin such as polymethyl methacrylate; a copolymer, a polymer alloy or a polymer blend containing these polymers can be used. These may be used alone or in combination of two or more. Among these, it is particularly preferable to use polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, copolymers containing these polymers, polymer alloys or polymer blends, and the like.
[0033]
The resin coating film can also be formed by applying a solution or dispersion containing a polymerizable compound to the end of the electrode mixture layer and polymerizing the polymerizable compound. Although the coating method is not specifically limited, For example, it can carry out by the screen printing method. The solution or dispersion may be liquid or pasty, and their viscosity may be arbitrarily controlled. The polymerizable compound is preferably polymerized by at least one means selected from the group consisting of heat, ultraviolet rays and electron beams.
The polymerizable compound has, for example, 1 to 3 polymerizable functional groups in the molecule. The polymerizable functional group is preferably at least one selected from the group consisting of an acrylate group and a methacrylate group. Further, the portion other than the polymerizable functional group is not particularly limited, and may be a polyalkylene oxide chain, for example.
[0034]
When the polymerizable compound is polymerized by heat, a polymerization initiator such as azobisisobutyronitrile, benzoyl peroxide, or acetyl peroxide is used. When the polymerizable compound is polymerized with ultraviolet rays, a polymerization initiator such as benzyl dimethyl ketal or benzoin isopropyl ether is used. When the polymerizable compound is polymerized with an electron beam, a polymerization initiator is not particularly required.
[0035]
An insulating material part can also be provided by sticking a resin tape on the current collector sheet around the electrode mixture layer. As the resin tape, an insulating base material and an insulating adhesive carried thereon can be used.
[0036]
Insulating base materials include olefin resins such as polyethylene, polypropylene and polymethylpentene; ester resins such as polyethylene terephthalate, polyethylene naphthalate, polycyclohexylenedimethylene terephthalate, polyarylate and polycarbonate; polyethylene oxide, polypropylene oxide and polyacetal Ether resins such as polyphenylene ether, polyether ether ketone and polyether imide; sulfone resins such as polysulfone and polyether sulfone; acrylonitrile resins such as polyacrylonitrile, AS resin and ABS resin; thioether resins such as polyphenylene sulfide Aromatic resin such as polystyrene; nitrogen-containing resin such as polyimide and aramid resin; polytetrafluoroethylene Acrylic resins polymethyl methacrylate; fluorine resin such as polyvinylidene fluoride copolymer containing these polymers can be used a polymer alloy or polymer blend, and the like. These may be used alone or in combination of two or more. Of these, polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyimide, aramid resin, copolymers containing these polymers, polymer alloys, polymer blends, and the like are particularly preferable.
[0037]
The insulating adhesive is not particularly limited, and for example, an acrylic resin, a butyl rubber resin, or the like can be used.
The thickness of a base material is 1-1000 micrometers, for example, and the thickness of the layer of an insulating adhesive is 0.1-100 micrometers, for example. The insulating adhesive may be provided only on one side of the base material or on both sides.
[0038]
When connecting the exposed portions of the conductive layers of the plurality of first current collector sheets or the second current collector sheets in parallel as shown in FIG. For example, the first side surface and the second side surface are covered with the coatings 17a and 17b of the conductive material, respectively. The thickness of the conductive material coating is, for example, about 0.01 to 1 mm. The conductive material films 17a and 17b thus obtained can be used for current collection as a first terminal and a second terminal, respectively. In order to obtain a good current collecting state, it is preferable that the contact area between the exposed portion of the conductive layer and the coating of the conductive material is larger, and the exposed portion of the conductive layer is 0.001 to 1 mm inside the coating of the conductive material. It is preferable to be buried to a depth of.
[0039]
1 to 3, the second electrode mixture layer has a larger area than the first electrode mixture layer. Such a structure is suitable for an electrode plate group of a lithium ion secondary battery in which the first electrode mixture layer is a positive electrode and the second electrode mixture layer is a negative electrode. When the first electrode mixture layer is a negative electrode and the second electrode mixture layer is a positive electrode, the area of the first electrode mixture layer is made larger than that of the second electrode mixture layer.
[0040]
Next, an example of a method for simultaneously manufacturing a plurality of electrode plate groups 10 will be described with reference to FIGS.
(A) Production of the first electrode
A resin sheet 21a having a size capable of providing a desired number of current collector sheets is prepared. Next, a plurality of conductive layers 26a having a predetermined shape pattern are provided at the same positions on both surfaces of the resin sheet 21a. For example, a conductive layer having a predetermined shape is formed on a resin sheet in a plurality of rows and a plurality of columns as shown in FIG. Such a conductive layer can be obtained by covering a resin sheet with a mask having a matrix-like opening and depositing metal on the resin sheet portion exposed from the opening.
[0041]
As shown in FIG. 4, a plurality of conductive layers 26a each having the size of two electrodes are formed on the resin sheet 21a. That is, when obtaining 2n electrodes, n conductive layers are formed on one side of the resin sheet. Next, as shown in FIG. 5, two first electrode mixture layers 22a are formed on each conductive layer 26a. An exposed portion 23a of the conductive layer having no mixture is left between the two first electrode mixture layers. In FIG. 5, an electrode mixture layer of 3 rows and 3 columns is drawn, but usually more conductive layers and electrode mixture layers are formed on a larger current collector sheet.
[0042]
The first electrode mixture layer is formed by applying a paste made of the first electrode mixture to the entire surface except for the central portion of the conductive layer. The coating method is not particularly limited, but it is preferable to employ screen printing, pattern coating, or the like. The exposed portion of the conductive layer to which the paste is not applied becomes the connection portion 24a with the first terminal after the electrode plate group is configured. The first electrode mixture is prepared by mixing the active material, conductive material, binder, and the like of the first electrode with a dispersion medium. The coating film of the paste is dried, and the dried coating film is rolled with a roller to increase the mixture density.
[0043]
When the first electrode is a positive electrode of a lithium ion secondary battery, for example, a lithium-containing transition metal oxide can be preferably used as the active material. Examples of the lithium-containing transition metal oxide include Li_xCoO_z, Li_xNiO_z, Li_xMnO_z, Li_xCo_yNi_1-yO_z, Li_xCo_fV_1-fO_z, Li_xNi_1-yM_yO_z(M = Ti, V, Mn, Fe), Li_xCo_aNi_bM_cO_z(M = Ti, Mn, Al, Mg, Fe, Zr), Li_xMn₂O_Four, Li_xMn_{2 (1-y)}M_2yO_Four(M = Na, Mg, Sc, Y, Fe, Co, Ni, Ti, Zr, Cu, Zn, Al, Pb, Sb). However, the x value varies in the range of 0 ≦ x ≦ 1.2 depending on the charge / discharge of the battery. Also, 0 ≦ y ≦ 1, 0.9 ≦ f ≦ 0.98, 1.9 ≦ z ≦ 2.3, a + b + c = 1, 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c <1 is there. These may be used alone or in combination of two or more.
[0044]
When the first electrode is a negative electrode of a lithium ion secondary battery, examples of the active material include lithium, a lithium alloy, an intermetallic compound, a carbon material, an organic compound that can occlude / release lithium ions, an inorganic compound, and a metal complex. Organic polymer compounds and the like can be preferably used. These may be used alone or in combination of two or more. Examples of carbon materials include coke, pyrolytic carbon, natural graphite, artificial graphite, mesocarbon microbeads, graphitized mesophase microspheres, vapor-grown carbon, glassy carbon, carbon fibers (polyacrylonitrile-based, pitch-based, cellulose-based, Vapor phase growth system), amorphous carbon, and organic compound fired body. Of these, natural graphite and artificial graphite are particularly preferable.
[0045]
As the conductive material, for example, carbon black such as acetylene black, graphite or the like is used. As the binder, for example, a fluororesin such as polyvinylidene fluoride and polytetrafluoroethylene, an acrylic resin, a styrene butadiene rubber, an ethylene propylene terpolymer, and the like can be used.
[0046]
At least the first electrode mixture layer that is adjacent to the exposed portion of the conductive layer of the second current collector sheet in the electrode plate group, ie, the second side surface of the electrode plate group. An insulating material portion is formed on the peripheral edge portion of the one-electrode mixture layer. You may coat | cover an insulating material also in the peripheral part of the 1st electrode mixture layer which will be distribute | arranged to the 3rd side surface and 4th side surface of an electrode group. The insulating material portion may be formed by the method already described, or may be formed by another method. The insulating material part formed in the peripheral part of the 1st electrode mixture layer turns into a 1st insulating material part in an electrode group.
[0047]
(B) Production of second electrode
The 2nd electrode which has the 2nd electrode mixture layer on both sides can be produced by the same method as the 1st electrode. That is, a plurality of conductive layers having a predetermined pattern are provided at the same position on both surfaces of the resin sheet 21b having a size capable of providing a desired number of current collector sheets, and the second electrode mixture layer 22b is provided on each conductive layer. Are formed two by two. An exposed portion 23b of the conductive layer having no mixture is left between the two second electrode mixture layers. The exposed portion of the conductive layer to which the paste is not applied becomes a connection portion 24b with the second terminal in the electrode plate group. The second electrode having the second electrode mixture layer only on one side can be produced by the same method as described above except that the conductive layer, the second electrode mixture layer and the insulating material are not provided on the other side.
[0048]
At least the second electrode mixture layer adjacent to the exposed portion of the conductive layer of the first current collector sheet in the electrode plate group, ie, the first side surface of the electrode plate group. An insulating material portion is formed on the peripheral edge portion of the two-electrode mixture layer. You may coat | cover an insulating material also on the peripheral part of the 2nd electrode mixture layer which will be distribute | arranged to the 3rd side surface and 4th side surface of an electrode group. The insulating material portion may be formed by the method already described, or may be formed by another method. The insulating material part formed in the peripheral part of the 2nd electrode mixture layer turns into a 2nd insulating material part in an electrode group.
[0049]
(C) Production of electrode group
The produced assembly composed of a plurality of first electrodes and the assembly composed of a plurality of second electrodes are stacked via a separator. At this time, the first electrode mixture layer 22a of the first electrode and the second electrode mixture layer 22b of the second electrode face each other and are laminated. The exposed portion 23a and the insulating material portion of the conductive layer in the first electrode face the insulating material portion and the exposed portion 23b of the conductive layer in the second electrode, respectively. On both outermost surfaces, a pair of second electrodes having a second electrode mixture layer is disposed only on one side, the inner electrodes are sandwiched between these, and the whole is pressed. In this way, an assembly composed of a plurality of electrode plate stacks can be obtained.
[0050]
As the separator, a woven fabric or a non-woven fabric made of an olefin polymer such as polyethylene or polypropylene or glass fiber can be used. A solid electrolyte or gel electrolyte can also be used as a separator. For the solid electrolyte, for example, polyethylene oxide, polypropylene oxide or the like can be used as the matrix material. As the gel electrolyte, for example, a nonaqueous electrolyte solution described later can be used which is held in a matrix made of a polymer material. As the polymer material for forming the matrix, polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, or the like can be used. These may be used alone or in combination of two or more. Among these, it is particularly preferable to use a copolymer of vinylidene fluoride and hexafluoropropylene, or a mixture of polyvinylidene fluoride and polyethylene oxide.
[0051]
An assembly composed of a plurality of electrode plate stacks is divided for each electrode plate stack. The first electrode and the second electrode are cut along the arrow direction shown in FIG. The exposed portion of the conductive layer forms connection portions 24a and 24b with the terminals by cutting, and the exposed portion of the resin sheet on the opposite side forms insulating portions 25a and 25b by cutting. In the four side surfaces of the electrode plate stack thus obtained, the end portions of the current collector sheets and the end portions of the separators are arranged almost flush with each other, but the conductive portions of electrodes having different polarities are arranged on the side surfaces. No face to face. Moreover, since the possibility of a short circuit is further reduced by the first insulating material portion and the second insulating material portion, an extremely reliable electrode plate group can be obtained.
[0052]
When the above-described method is applied using a metal foil that has been generally used as a current collector sheet, metal burrs generated during cutting become a problem. Metal burrs break through the separator and cause a major short circuit. Therefore, it is important to prevent the occurrence of metal burrs, but it is extremely difficult to cut the metal foil without causing metal burrs. On the other hand, when a current collector sheet made of a resin sheet is used, since most of the cut surface is occupied by the resin, no metal burrs are generated. As a result, the reliability of the electrochemical device is greatly improved.
[0053]
A first terminal can be obtained by covering the first side surface in which the exposed portions of the conductive layer of the first current collector sheet and the insulating portions of the second current collector sheet are alternately arranged with a coating of a conductive material. For example, the first side surface can be coated with the metal film by spraying molten or semi-molten metal fine particles on the first side surface. The metal film thus formed is automatically electrically connected to the exposed portion of the conductive layer of the first current collector sheet. In addition, since the 2nd insulating material part is formed in the end surface of the 2nd electrode mixture layer distribute | arranged to the 1st side surface, a short circuit with a metal film and a 2nd electrode does not occur. The second side surface in which the exposed portions of the conductive layer of the second current collector sheet and the insulating portions of the first current collector sheet are alternately arranged is also covered with a metal film in the same manner as described above to obtain the second terminal. be able to.
[0054]
When the first terminal or the second terminal is a positive electrode terminal, it is preferable to use aluminum powder as the metal fine particles. When the first terminal or the second terminal is a negative electrode terminal, it is preferable to use copper powder as the metal fine particles.
[0055]
An assembly of electrode plate groups can also be obtained by using an assembly composed of a plurality of first electrodes and an assembly composed of a plurality of second electrodes as shown in FIG. When obtaining such an assembly composed of the first electrodes, a plurality of rows of strip-like conductive layers are formed at the same position on both surfaces of the resin sheet 31a having a size capable of providing a desired number of current collector sheets. Such a conductive layer can be obtained by covering a resin sheet with a mask having a strip-shaped opening and depositing a metal on the resin sheet exposed from the opening. Here, a plurality of rows of conductive layers having a size corresponding to two rows of electrode mixture layers are formed on the resin sheet 31a. That is, when obtaining 2n rows of electrode mixture layers, n rows of conductive layers are formed on one side of the resin sheet.
[0056]
Two rows of strip-shaped first electrode mixture layers 32a are formed on each strip-shaped conductive layer. An exposed portion 33a of the conductive layer having no mixture is left between the two strips of the first electrode mixture layer 32a. The strip-shaped first electrode mixture layer 32a is formed by applying a paste made of the same first electrode mixture as described above to the entire surface excluding the central portion of the conductive layer. The coating method is the same as in the case of the laminated electrode plate group. The exposed portion 33a of the conductive layer to which the paste is not applied becomes a connection portion 34a with the first terminal. In the electrode plate group, a first insulating material portion is formed on the peripheral portion of the first electrode mixture layer that is adjacent to the exposed portion of the conductive layer of the second current collector sheet.
[0057]
Even when obtaining an assembly composed of the second electrodes, a plurality of rows of strip-like conductive layers are provided at the same positions on both surfaces of the resin sheet 31b having a size capable of providing a desired number of current collector sheets. On top, two rows of strip-shaped second electrode mixture layers 32b are formed. An exposed portion 33b of the conductive layer having no mixture is left between the two rows of strip-shaped second electrode mixture layers. The exposed portion of the conductive layer to which the paste is not applied becomes a connection portion 34b with the second terminal. In the electrode plate group, a second insulating material portion is formed on the peripheral edge portion of the second electrode mixture layer adjacent to the exposed portion of the conductive layer of the first current collector sheet.
[0058]
When such an assembly of electrode plate groups is divided into electrode plate stacks along the direction of the arrows shown in FIG. 6, the exposed portions of the conductive layer are cut to form connection portions 34a and 34b with terminals, The exposed portion of the opposite resin sheet forms insulating portions 35a and 35b by cutting. In the four side surfaces of the electrode plate stack thus obtained, the end portions of the respective current collector sheets and the end portions of the separators are substantially flush, but the first side surface and the second side surface are different. The conductive portions of the polar electrodes do not face each other on each side. Moreover, since the possibility of a short circuit is further reduced by the first insulating material portion and the second insulating material portion, an extremely reliable electrode plate group can be obtained.
[0059]
The obtained electrode plate group is housed together with a predetermined electrolyte in a case having a predetermined shape as necessary. As the case, for example, a stainless steel plate, an aluminum plate or the like processed into a predetermined shape, an aluminum foil (aluminum laminate sheet) having a resin film on both sides, a resin case, or the like is used. In the case where the electrochemical element is, for example, a lithium ion secondary battery, an electrolytic solution in which a lithium salt is dissolved in a nonaqueous solvent is used. The lithium salt concentration in the electrolytic solution is, for example, 0.5 to 1.5 mol / L.
[0060]
Nonaqueous solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, non-dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, and the like. Cyclic carbonate, aliphatic formate such as methyl formate, methyl acetate, methyl propionate, ethyl propionate, γ-lactone such as γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, 1,2-di Acyclic ethers such as ethoxyethane and ethoxymethoxyethane, cyclic ethers such as tetrahydrofuran and 2-methyl-tetrahydrofuran, dimethylsulfoxy , 1,3-dioxolane, trimethyl phosphate, triethyl phosphate, alkyl phosphate esters and their fluorides, such as trioctyl phosphate can be used. These are preferably used in combination of plural kinds. In particular, a mixture containing a cyclic carbonate and an acyclic carbonate, a mixture containing a cyclic carbonate, an acyclic carbonate, and an aliphatic carboxylic acid ester are preferred.
[0061]
LiPF includes LiPF₆, LiBF_FourLiClO_FourLiAlCl_Four, LiSbF₆, LiSCN, LiCl, LiCF_ThreeSO_Three, LiCF_ThreeCO₂, LiAsF₆, LiN (CF_ThreeSO₂)₂, Li₂B_TenCl_Ten, LiN (C₂F_FiveSO₂)₂, LiPF_Three(CF_Three)_Three, LiPF_Three(C₂F_Five)_ThreeEtc. can be used. These may be used alone or in combination of two or more, but at least LiPF6 is preferably used.
For example, if the electrode plate group has a size of 1 to 300 mm in length, 1 to 300 mm in width, and 0.01 to 20 mm in thickness, it can be efficiently manufactured by the above manufacturing method.
[0062]
Next, an example of a method for manufacturing a wound electrode group as shown in FIG. 7 will be described. FIG. 7 is a conceptual diagram of a partially wound electrode plate group drawn with the first electrode as the center, and a mixture layer and electrode plates on the outer peripheral side are omitted.
(A) Production of the first electrode
The first electrode used for the wound electrode group has the same structure as the first electrode used for the stacked electrode group except that it has a strip shape. The manufacturing method of the first electrode is almost the same as that of the stacked type. For example, an assembly including the first electrodes as shown in FIG. 6 is produced. An insulating material portion 36a is provided on the peripheral portion of the first electrode mixture layer adjacent to the exposed portion of the resin sheet 31a. This portion is adjacent to the connection portion 34b with the second terminal of the second current collector sheet in the electrode plate group.
(B) Production of second electrode
An assembly composed of the second electrode as shown in FIG. 6 is produced. An insulating material portion 36b is provided on the peripheral portion of the second electrode mixture layer adjacent to the exposed portion of the resin sheet 31b. This portion is adjacent to the connecting portion 34a with the first terminal of the first current collector sheet in the electrode plate group.
[0063]
(C) Production of electrode group
The assembly composed of the first electrode and the assembly composed of the second electrode are wound through the separator 40. At this time, the strip-shaped first electrode mixture layer 32a and the second electrode mixture layer 32b face each other, and the exposed portion 34a and the insulating portion 35a of the conductive layer in the first electrode are respectively connected to the insulating portion 35b in the second electrode. And the exposed portion 34b of the conductive layer. As a result, a long cylindrical aggregate composed of a plurality of wound electrode plate groups alternately arranged in opposite directions is obtained.
[0064]
On one side surface (bottom surface A) of the electrode plate group obtained by dividing such an assembly, an exposed portion of the conductive layer of the first current collector sheet and an insulating portion of the second current collector sheet are provided. They are arranged concentrically in an alternating manner. On the other side surface (bottom surface B), the exposed portions of the conductive layer of the second current collector sheet and the insulating portions of the first current collector sheet are alternately arranged concentrically.
[0065]
The first terminal 41 and the second terminal 42 can be formed by covering the bottom surface A and the bottom surface B with a metal film, respectively, in the same manner as described above. On the first terminal side, since the insulating material portion 36b is provided on the end surface of the second electrode mixture layer, a short circuit between the first terminal and the second electrode is reliably prevented, and on the second terminal side, Since the insulating material portion 36a is provided on the end face of the first electrode mixture layer, a short circuit between the second terminal and the first electrode is also reliably prevented.
[0066]
【Example】
Example 1
In this example, a stacked lithium ion secondary battery was manufactured in the following manner.
(A) Production of the first electrode
A sheet of polyethylene terephthalate (hereinafter referred to as PET) having a width of 198 mm, a length of 282 mm, and a thickness of 7 μm was prepared. Next, a plurality of rectangular (65 mm × 46 mm) copper deposited films arranged in 3 rows and 6 columns were formed at the same positions on both sides of the PET sheet using a mask having a matrix-shaped opening. The thickness of the copper vapor deposition film was 0.1 μm.
[0067]
By mixing 100 parts by weight of active material spheroidal graphite (graphitized mesophase spherules), 3 parts by weight of styrene butadiene rubber as a binder, and an appropriate amount of carboxymethyl cellulose aqueous solution as a dispersion medium, the first electrode mixture A paste consisting of was prepared.
This paste was applied to the entire surface except for the central portion of each deposited film. As a result, two 32 mm × 46 mm first electrode mixture layers were formed on each deposited film. Between the two 1st electrode mixture layers, the exposed part of the copper vapor deposition film which does not have an electrode mixture layer was left in the groove | channel shape of width 1mm. Thereafter, the coating film of the paste was dried, and the dried coating film was rolled with a roller until the thickness became 70 μm.
[0068]
10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) was dissolved in 90 parts by weight of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to prepare an NMP solution of PVDF.
The NMP solution is applied by screen printing on the portion of the peripheral edge of the first electrode mixture layer opposite to the portion adjacent to the exposed portion of the deposited film, and dried at 80 ° C. A coating film of polyvinylidene fluoride having a thickness of 3 mm and a dried thickness of 70 μm was formed as an insulating material part. Thus, a first electrode assembly having a first electrode mixture layer of 6 rows and 6 columns on both surfaces was obtained.
[0069]
(B) Production of second electrode
A second electrode having a second electrode mixture layer on both sides was produced.
A PET sheet having a width of 198 mm, a length of 282 mm, and a thickness of 7 μm was prepared. Next, a plurality of rectangular (64 mm × 45 mm) aluminum vapor deposition films arranged in 3 rows and 6 columns were formed at the same positions on both sides of the PET sheet using a mask having a matrix-like opening. The thickness of the Al vapor deposition film was 0.1 μm.
[0070]
Active material lithium cobalt oxide (LiCoO₂) By mixing 100 parts by weight, 3 parts by weight of acetylene black as a conductive material, 7 parts by weight of polyvinylidene fluoride as a binder, and an appropriate amount of an aqueous solution of carboxymethylcellulose as a dispersion medium, A paste was prepared. This paste was applied to the entire surface except for the central portion of each deposited film. As a result, two 31 mm × 45 mm second electrode mixture layers were formed on each deposited film. Between the two 2nd electrode mixture layers, the exposed part of the vapor deposition film of Al which does not have a mixture was left in the groove shape of width 2mm. Thereafter, the coating film of the paste was dried, and the dried coating film was rolled with a roller until the thickness became 70 μm.
[0071]
Of the peripheral part of the obtained second electrode mixture layer, the NMP solution is applied by screen printing on the part opposite to the part adjacent to the exposed part of the deposited film, and dried at 80 ° C., A coating film of polyvinylidene fluoride having a width of 0.3 mm and a thickness of 70 μm after drying was formed as an insulating material part. Thus, an assembly of second electrodes having a second electrode mixture layer of 6 rows and 6 columns on both surfaces was obtained.
Next, a second electrode having a second electrode mixture layer only on one side was produced in the same manner as described above except that the conductive layer, the second electrode mixture layer and the insulating material were not provided on the other side.
[0072]
(C) Production of electrode group
Two assemblies composed of the first electrode having the first electrode mixture layer on both surfaces and one assembly composed of the second electrode having the second electrode mixture layer on both surfaces were sandwiched via a separator. At this time, the first electrode mixture layer and the second electrode mixture layer face each other. In addition, the exposed portion of the vapor deposition film and the insulating material portion made of polyvinylidene fluoride coating on the first electrode face the insulating material portion of the second electrode made of polyvinylidene fluoride coating and the exposed portion of the vapor deposition film, respectively. It was. A pair of second electrodes having the second electrode mixture layer on only one side was disposed on both outermost surfaces, and the inner electrodes were sandwiched between them, and the whole was pressed. As a result, an assembly composed of a plurality of electrode plate stacks was obtained.
[0073]
An assembly composed of a plurality of electrode plate stacks was divided for each electrode plate stack so that the cutting position was aligned with the center of the exposed portion of the vapor deposition film in the first electrode and the center of the exposed portion of the vapor deposition film in the second electrode. As a result, as many as 36 electrode plate stacks could be obtained at a time through a series of coating and laminating processes. On the four side surfaces of the electrode plate stack thus obtained, the end portions of the current collector sheets and the end portions of the separators were arranged flush with each other.
[0074]
On one side surface (first side surface), exposed portions of the deposited film of the first current collector sheet and exposed portions of PET of the second current collector sheet were alternately arranged. On the opposite second side surface, the exposed portions of the deposited film of the second current collector sheet and the exposed portions of PET of the first current collector sheet were alternately arranged. On the remaining two side surfaces, the exposed portions of PET of each current collector sheet were arranged.
[0075]
Semi-molten copper fine particles were sprayed on the first side surface where the exposed portions of the copper deposited film of the first current collector sheet and the exposed portions of the PET of the second current collector sheet were alternately arranged. As a result, a copper film having a thickness of 0.5 mm was formed on the first side surface. The exposed portion of the copper deposited film was buried to a depth of 0.2 mm inside the copper film. Since the end surface of the second electrode mixture layer disposed on the first side surface is covered with a polyvinylidene fluoride coating film, the copper film formed by spraying and the second electrode did not contact each other. . This copper film was used as a negative electrode terminal as it was.
[0076]
Semi-molten aluminum fine particles were sprayed on the second side surface where the exposed portions of the Al deposited film of the second current collector sheet and the exposed portions of the PET of the first current collector sheet were alternately arranged. As a result, an aluminum film having a thickness of 0.5 mm was formed on the second side surface. The exposed portion of the deposited Al film was buried to a depth of 0.2 mm inside the aluminum film. Since the end surface of the first electrode mixture layer disposed on the second side surface is covered with a polyvinylidene fluoride coating film, the aluminum film formed by spraying and the first electrode did not contact each other. . This aluminum film was used as a positive electrode terminal as it was.
[0077]
[Charge / discharge test]
Lead wires were connected to the copper film (negative electrode terminal) and the aluminum film (positive electrode terminal) of the obtained electrode plate group, respectively, and a charge / discharge test was performed using an external charge / discharge device. The electrolyte used here was LiPF in a mixed solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 30:70.₆Was dissolved at a concentration of 1 mol / L.
Charging / discharging was performed in a 20 ° C. atmosphere. Charging and discharging are each 2.5 mA / cm with respect to the electrode area.²The current mode was performed. The end-of-charge voltage was 4.2V. The final discharge voltage was 3.0V. The electric capacity obtained under the above conditions was 900 mAh.
[0078]
[Short-circuit rate]
100 similar batteries were produced, and the vicinity of the current collecting terminals of these batteries was crushed with a metal round bar, and then the battery voltage was measured to examine the number of batteries that could cause an internal short circuit. There was no battery that could cause an internal short circuit.
[0079]
<< Comparative Example 1 >>
A first electrode having a first electrode mixture layer having the same composition and thickness as in Example 1 is prepared using a conventionally used core material made of copper foil, and a core material made of aluminum foil is used. The 2nd electrode which consists of the 2nd electrode mixture layer of the same composition and thickness as Example 1 was produced. These were stacked to produce a battery with the same capacity of 900 mAh as in Example 1. The end portion of the first electrode protrudes from the first side surface of the electrode plate group, and the end portion of the second electrode protrudes from the second side surface located on the opposite side of the first side surface. The insulating material part covering the end part of the electrode mixture layer was not provided on the first electrode or the second electrode. The same polarity plates were connected with leads to complete the battery. The capacity of the battery obtained was the same as that of Example 1, but the battery volume was about 1.2 times that of the battery of Example 1. When 100 similar batteries were produced and the occurrence rate of short circuit was examined, occurrence of a short circuit was confirmed in 2 batteries.
[0080]
Example 2
In this example, a wound-type lithium ion secondary battery was manufactured in the following manner.
(A) Production of the first electrode
A sheet of polyethylene terephthalate (hereinafter referred to as PET) having a width of 198 mm, a length of 506 mm, and a thickness of 7 μm was prepared. Next, using a mask having a matrix-shaped opening, a plurality of strip-shaped (65 mm × 506 mm) copper deposited films arranged in three rows were formed at the same positions on both sides of the PET sheet. The thickness of the copper vapor deposition film was 0.1 μm.
[0081]
By mixing 100 parts by weight of active material spheroidal graphite (graphitized mesophase spherules), 3 parts by weight of styrene butadiene rubber as a binder, and an appropriate amount of carboxymethyl cellulose aqueous solution as a dispersion medium, the first electrode mixture A paste consisting of was prepared. This paste was applied to the entire surface except for the central portion of each deposited film, and two rows of 32 mm × 506 mm strip-shaped first electrode mixture layers were formed on each deposited film. Between the two rows of strip-shaped first electrode mixture layers, an exposed portion of a copper deposited film without the first electrode mixture was left in a groove shape having a width of 1 mm. Thereafter, the coating film of the paste was dried, and the dried coating film was rolled with a roller until the thickness became 70 μm.
[0082]
In the peripheral portion of the first electrode mixture layer, on the opposite side of the portion adjacent to the exposed portion of the deposited film, a polyfluoride having a width of 0.3 mm and a thickness of 70 μm after drying is applied in the same manner as in Example 1. An insulating material part was formed by forming a vinylidene chloride coating. Thus, a first electrode assembly having six rows of strip-like first electrode mixture layers on both surfaces was obtained.
[0083]
(B) Production of second electrode
The 2nd electrode which has a strip | belt-shaped 2nd electrode mixture layer on both surfaces was produced.
A PET sheet having a width of 198 mm, a length of 506 mm, and a thickness of 7 μm was prepared. Next, a plurality of strip-shaped (64 mm × 506 mm) aluminum deposited films arranged in three rows were formed at the same positions on both sides of the PET sheet using a mask having a matrix-shaped opening. The thickness of the Al vapor deposition film was 0.1 μm.
[0084]
Active material lithium cobalt oxide (LiCoO₂) By mixing 100 parts by weight, 3 parts by weight of acetylene black as a conductive material, 7 parts by weight of polyvinylidene fluoride as a binder, and an appropriate amount of an aqueous solution of carboxymethylcellulose as a dispersion medium, A paste was prepared. This paste was applied to the entire surface except for the central portion of each deposited film, and two rows of 31 mm × 506 mm strip-shaped second electrode mixture layers were formed on each deposited film. Between the two rows of the second electrode mixture layer, an exposed portion of an Al deposited film not having the second electrode mixture was left in a groove shape having a width of 2 mm. Thereafter, the coating film of the paste was dried, and the dried coating film was rolled with a roller until the thickness became 70 μm.
[0085]
In the peripheral portion of the second electrode mixture layer, on the opposite side of the portion adjacent to the exposed portion of the deposited film, a polyfluoride having a width of 0.3 mm and a thickness of 70 μm after drying is applied in the same manner as in Example 1. An insulating material part was formed by forming a vinylidene chloride coating. Thus, an assembly of second electrodes having six rows of second electrode mixture layers on both surfaces was obtained.
[0086]
(C) Production of electrode group
The assembly of the first electrode and the assembly of the second electrode were overlapped via a separator and then wound. At this time, the first electrode mixture layer and the second electrode mixture layer face each other, and the exposed portion of the vapor deposition film and the insulating material portion made of the polyvinylidene fluoride coating on the first electrode are respectively connected to the second electrode. It was made to face the insulating material part which consists of a coating film of polyvinylidene fluoride, and the exposed part of a vapor deposition film. As a result, a long cylindrical assembly composed of a plurality of wound electrode groups arranged alternately in opposite directions was obtained.
[0087]
The assembly thus obtained was cut at the center of the exposed portion of the vapor deposition film in the first electrode and at the center of the exposed portion of the vapor deposition film in the second electrode, and divided into electrode plates. As a result, six electrode plate groups could be obtained at a time through a series of coating and winding processes.
[0088]
Semi-molten copper fine particles were sprayed on the side surface (first bottom surface) where the exposed portions of the copper deposited film of the first current collector sheet and the PET resin portions of the second current collector sheet were alternately arranged. However, in order to provide an injection hole for injecting the electrolytic solution inside the electrode plate group, a mask was put on the corresponding portion. As a result, a copper film having a thickness of 0.5 mm was formed on the first bottom surface. At this time, the exposed portion of the deposited copper film was buried to a depth of 0.2 mm inside the copper film. Since the end surface of the second electrode mixture layer disposed on the first bottom surface is covered with a polyvinylidene fluoride coating film, the copper film formed by spraying and the second electrode did not contact each other. . This copper film was used as a negative electrode terminal as it was.
[0089]
Semi-molten aluminum fine particles were sprayed on the side surface (second bottom surface) where the exposed portions of the Al deposited film of the second current collector sheet and the PET resin portions of the first current collector sheet were alternately arranged. However, in order to provide an injection hole for injecting the electrolytic solution inside the electrode plate group, a mask was put on the corresponding portion. As a result, an aluminum film having a thickness of 0.5 mm was formed on the second bottom surface. At this time, the exposed portion of the Al vapor deposition film was buried to a depth of 0.2 mm inside the aluminum film. Since the end surface of the first electrode mixture layer disposed on the second bottom surface is covered with a polyvinylidene fluoride coating film, the aluminum film formed by spraying and the first electrode did not contact each other. . This aluminum film was used as a positive electrode terminal as it was.
[0090]
The electrode plate group thus obtained was housed in a stainless steel cylindrical battery case, and the copper film on the bottom surface of the electrode plate group was connected to the inner bottom surface of the case. The aluminum film on the upper surface of the electrode plate group was connected via an aluminum lead to the back side of a sealing plate having an insulating gasket around it. Next, the electrolytic solution was poured into the case, and the electrolytic solution was impregnated inside the electrode plate group. Thereafter, the opening of the case was sealed with a sealing plate to complete a cylindrical battery. The electrolyte used here was LiPF in a mixed solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 30:70.₆Was dissolved at a concentration of 1 mol / L.
[0091]
<< Comparative Example 2 >>
A wound type lithium ion secondary battery was produced in the same manner as before.
That is, a first electrode composed of a 32 × 506 mm strip-shaped copper foil and a first electrode mixture layer having the same composition and thickness as those of Example 2 carried on both sides thereof was produced, and a 31 × 506 mm strip-shaped aluminum foil was produced. And the 2nd electrode which consists of a 2nd electrode mixture layer of the same composition and thickness as Example 2 carry | supported on both surfaces was produced. Each electrode plate was provided with an uncoated portion of the electrode mixture layer for connecting the current collecting tab, and the current collecting tab was connected thereto. These 1st electrode and 2nd electrode were wound through the separator, and the electrode group was produced.
[0092]
The electrode plate group thus obtained was housed in a stainless steel cylindrical battery case 1.2 times larger in diameter than that used in Example 2, and the second electrode lead was welded to the inner bottom surface of the case. Moreover, the 1st electrode lead was connected to the back side of the sealing board which has arrange | positioned the insulation gasket around. Next, the electrolytic solution was poured into the case, and the same electrolytic solution as in Example 2 was impregnated inside the electrode plate group. Thereafter, the opening of the case was sealed with a sealing plate to complete a cylindrical battery. The reason why the battery case larger than that of Example 2 was required in Comparative Example 2 was that the current collecting tab was interposed inside the electrode plate group, so that the diameter of the electrode plate group increased. The capacity of the battery of Example 2 and Comparative Example 2 was the same, but the battery of Comparative Example 2 was 1.2 times larger than the battery of Example 2.
[0093]
[Charge / discharge test]
The batteries of Example 2 and Comparative Example 2 were charged and discharged in a 20 ° C. atmosphere. Charging and discharging are each 2.5 mA / cm with respect to the electrode area.²The current mode was performed. The end-of-charge voltage was 4.2V. The final discharge voltage was 3.0V. The electric capacities of the batteries of Example 2 and Comparative Example 2 obtained under the above conditions were both 900 mAh.
[0094]
[Short-circuit rate]
100 batteries of Example 2 and Comparative Example 2 were produced, respectively, and the vicinity of the current collecting terminals of these batteries was crushed, and then the battery voltage was measured to determine the number of batteries that could cause an internal short circuit. It was. The number of batteries that could cause an internal short circuit was zero in Example 2, but was two in Comparative Example 2.
[0095]
Example 3
In 100 parts by weight of polyethylene oxide diacrylate, 0.1 part by weight of benzyl dimethyl ketal was dissolved, and an acrylate solution for starting polymerization by ultraviolet irradiation was prepared.
Instead of the PVDF NMP solution, the acrylate solution was applied with a width of 0.3 mm to predetermined peripheral edges of the first electrode mixture layer and the second electrode mixture layer by screen printing. Thereafter, using a high-pressure mercury lamp with a maximum output wavelength of 365 nm, the coating film was irradiated with ultraviolet rays for 1 minute to cure the coating film. The thickness of the cured coating film was 70 μm. Thus, an electrode plate group was produced in the same manner as in Example 1 except that the insulating material portion was provided.
[0096]
Example 4
Implemented except that a resin tape having a width of 0.3 mm and a thickness of 70 μm was applied to the predetermined peripheral portions of the first electrode mixture layer and the second electrode mixture layer in place of the polyvinylidene fluoride coating film. In the same manner as in Example 1, an electrode plate group was produced. Here, a resin tape composed of a polypropylene base material having a thickness of 60 μm and a pressure-sensitive adhesive layer having a thickness of 5 μm supported on both surfaces thereof was used. An acrylic resin was used as the adhesive.
[0097]
[Charge / discharge test]
The batteries of Examples 3 and 4 were charged and discharged in a 20 ° C. atmosphere in the same manner as in Example 1. That is, charging and discharging are each 2.5 mA / cm with respect to the electrode area.²The current mode was performed. The end-of-charge voltage was 4.2V. The final discharge voltage was 3.0V. The electric capacities of the batteries of Examples 3 and 4 obtained under the above conditions were all 900 mAh.
[0098]
[Short-circuit rate]
100 batteries of each of Examples 3 and 4 were produced, the vicinity of the current collecting terminals of these batteries was crushed, and then the battery voltage was measured to examine the number of batteries that could cause an internal short circuit. The number of batteries that could cause an internal short circuit was zero in any of the examples.
[0099]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electrochemical element having a very low possibility of short circuit, high reliability, and high electric capacity. And according to this invention, a several electrochemical element can be manufactured efficiently simultaneously. By using a non-aqueous electrolyte secondary battery including such an electrochemical element, a highly reliable mobile phone, portable information terminal device, camcorder, personal computer, PDA, portable acoustic device, electric vehicle, power source for load leveling Etc. can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a laminated electrode plate group according to the present invention.
2 is a cross-sectional view taken along the line aa of the stacked electrode plate group of FIG. 1 when there is no insulating material portion on the third side surface and the fourth side surface.
3 is a cross-sectional view taken along the line aa of the multilayered electrode plate group of FIG. 1 when an insulating material portion is provided on the third side surface and the fourth side surface.
FIG. 4 is a top view of a current collector sheet for obtaining an assembly of first electrodes or second electrodes.
FIG. 5 is a conceptual diagram showing a cut portion of an assembly composed of a first electrode and an assembly composed of a second electrode.
FIG. 6 is a conceptual diagram showing a cut location of an assembly made up of another first electrode and an assembly made up of another second electrode.
FIG. 7 is a vertical cross-sectional conceptual diagram of a wound electrode plate group according to the present invention.
[Explanation of symbols]
10 plate group
11a, b Resin sheet
11x, y End of resin sheet
12a, b Conductive layer
12x, y End of conductive layer
13a First current collector sheet
13b Second current collector sheet
14a First electrode mixture layer
14b Second electrode mixture layer
15a First electrode
15b, b 'second electrode
16 Separator
17a Coating of conductive material
17b Coating of conductive material
18a First insulating material part
18b Second insulating material part
18c 3rd insulation material part
18d Fourth insulating material part
21a, b Resin sheet
22a First electrode mixture layer
22b Second electrode mixture layer
23a, b Exposed portion of conductive layer
24a Connection with first terminal
24b Connection with second terminal
25a, b Insulation part
31a, b Resin sheet
32a Band-shaped first electrode mixture layer
32b Band-shaped second electrode mixture layer
33a, b Exposed portion of conductive layer
34a Connection with first terminal
34b Connection with second terminal
35a, b insulation
36a, b Insulation material part
40 separator
41 1st terminal
42 Second terminal

Claims (11)

An electrochemical device having an electrode plate group consisting of (a) at least one first electrode, (b) at least one second electrode, and (c) a separator interposed between the first electrode and the second electrode. And
The first electrode (a) comprises a first current collector sheet and at least one first electrode mixture layer carried on the current collector sheet,
The second electrode (b) comprises a second current collector sheet and at least one second electrode mixture layer carried on the current collector sheet,
Each of the electrode mixture layers has an end covered with an insulating material,
Said insulating material, Ri least 1 Tanedea selected from the group consisting of resin film and a resin tape,
In the first side surface of the electrode plate group, the first current collector sheet and the first terminal are connected. In the second side surface of the electrode plate group, the second current collector sheet and the second terminal are connected. Are connected, and an end portion of the first electrode mixture layer covered with the insulating material is disposed on the second side surface and covered with the insulating material of the second electrode mixture layer An end is disposed on the first side surface;
The first current collector sheet and the second current collector sheet each have a conductive part and an insulating part, and the conductive part of the first current collector sheet and the conductive part of the second current collector sheet are respectively The end portions connected to the first terminal and the second terminal and covered with the insulating material of the first electrode mixture layer and the second electrode mixture layer are respectively insulated from the first current collector sheet. And the electrochemical element adjacent to the insulating part of the second current collector sheet . The electrode plate group, claim 1 having the other than the first and second side surfaces, the insulating part and / or the second current collector sheet side insulating portion is disposed in the first current collector sheet The electrochemical element as described. The electrochemical device according to claim 1 or 2, wherein the first terminal and the second terminal are located on opposite sides of the electrode plate group. The electrochemical element according to any one of claims 1 to 3 , wherein the electrode plate group has a side surface on which an insulating material is disposed in addition to the first side surface and the second side surface.   The electrochemical element according to claim 1, wherein the resin coating film is formed by applying a solution or dispersion containing an insulating resin to an end portion of the electrode mixture layer and drying. The insulating resin comprises at least one selected from the group consisting of polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and a copolymer, polymer alloy or polymer blend containing at least one of these. Item 6. The electrochemical element according to Item 5 .   The electrochemical of Claim 1 in which the said resin coating film is formed by applying the solution or dispersion liquid containing a polymeric compound to the edge part of an electrode mixture layer, and polymerizing the said polymeric compound. element. The electrochemical device according to claim 7, wherein the polymerizable compound is polymerized by at least one means selected from the group consisting of heat, ultraviolet rays and electron beams. The electrochemical device according to claim 7, wherein the polymerizable compound has at least one functional group selected from the group consisting of an acrylate group and a methacrylate group.   The electrochemical element according to claim 1, wherein the resin tape comprises an insulating base material and an insulating adhesive carried on the insulating base material. The insulating substrate is at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyimide, aramid resin and a copolymer containing at least one of these, a polymer alloy, or a polymer blend. The electrochemical device according to claim 10 .

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