JP2011233346A - Outer package for electrochemical device and electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outer package for electrochemical device having a sealing structure exhibiting excellent pressure resistance in which a plurality of power generation elements are housed while reducing the dead space.SOLUTION: The outer package for housing a plurality of power generation elements of an electrochemical device while interposing a barrier 7 between respective power generation elements has a sealing part consisting of a pair of laminate films 51 and 52 facing each other, and the marginal parts of the pair of laminate films 51 and 52 are bonded while sandwiching the barrier 7. At least a part of the sealing part becomes a built-in sealing part 5 contained in the outer package when the marginal parts of the pair of laminate films 51 and 52 are bent to the inner side of the outer package and bonded.

Description

  The present invention relates to an exterior body for an electrochemical device and an electrochemical device.

  As electrochemical devices such as batteries and electric double layer capacitors, those using an aluminum laminate outer package have been put into practical use. The aluminum laminate outer package is advantageous in that it is lightweight and has a high degree of freedom in shape.

  The structure of the conventional laminate exterior body has a structure in which a laminate film is sealed by a hot press or the like at an adhesive margin portion provided around the power generation element accommodating portion (see, for example, Patent Documents 1 to 4). Moreover, in an electrochemical device using such a laminate outer package, attempts have been made to insert two or more power generation elements into the outer package for the purpose of increasing the operating voltage (for example, Patent Documents 5 to 6). reference). In this case, since it is necessary to isolate | separate an electric power generation element within an exterior body, providing a partition between electric power generation elements is performed. The structure of the exterior body provided with the partition wall is a structure in which the partition wall and the laminate film are integrated by sandwiching the partition wall with a laminate film at the periphery of the power generation element accommodating portion and sealing with a hot press or the like. Are known.

  However, the above-described structure of the laminate outer package has a problem that a dead space corresponding to the paste margin occurs. For this reason, it has been proposed to save space by folding the adhesive margin part (seal part) of the laminate outer package (see, for example, Patent Documents 7 to 11).

JP 2000-77043 A JP 2000-133216 A JP 2000-149993 A JP 2000-285904 A JP 2006-221938 A JP 2005-79473 A Japanese Patent Laid-Open No. 2000-200585 JP 2000-251855 A JP 2000-268807 A JP 2001-325925 A Japanese Patent Application Laid-Open No. 2001-325943

  However, even in the structure of the laminate outer package described in Patent Documents 7 to 11, since the folded paste margin portion becomes a dead space, there is room for further reduction of the dead space. Moreover, in the structure of the laminated exterior body described in the said patent documents 1-4 and 7-11, when the internal pressure inside an exterior body rises, the problem that a paste margin part will be gradually spread and peeling will arise easily. is there.

  The present invention has been made in view of the above-described problems of the prior art, and can reduce dead space and has a seal structure with excellent pressure resistance, for an electrochemical device for accommodating a plurality of power generation elements therein. An object of the present invention is to provide an exterior body and an electrochemical device using the exterior body.

  In order to achieve the above object, the present invention provides an exterior body for accommodating a plurality of power generation elements of an electrochemical device in a state where a partition wall is sandwiched between the power generation elements, and a pair of opposing power generation elements It has a seal part composed of a laminate film and the partition, and the edges of the pair of laminate films are bonded together with the partition interposed therebetween, and at least a part of the seal part is the pair of laminate films. Provided is an exterior body for an electrochemical device, in which the edges of each are bent and bonded to the interior side of the exterior body to form a built-in seal portion accommodated inside the exterior body.

  According to such an exterior body for an electrochemical device, at least a part of the seal portion is a built-in seal portion of the above structure, so that the seal portion is compared with a conventional exterior body provided outside the exterior body. The dead space can be sufficiently reduced. In addition, the built-in seal portion having the above structure is less likely to peel off even when the internal pressure inside the exterior body increases, so that it does not work in the direction of expanding the seal portion, and can have excellent pressure resistance.

  Further, in the above-described conventional exterior body, the sealant tends to protrude from the end of the seal portion to the outside of the exterior body during hot pressing. Therefore, it is necessary to remove the protruding sealant, or if the sealant is not removed, the appearance deteriorates, the dead space increases due to the protruding sealant, or the process is caused by tearing or falling off of the protruding part. Problems such as defects are caused. On the other hand, according to the exterior body for an electrochemical device of the present invention, even if the sealant protrudes from the end of the seal portion during hot pressing, the sealant protrudes into the exterior body, so that the appearance deteriorates or the dead space There is no increase.

  The exterior body for an electrochemical device of the present invention preferably has a rectangular outer shape, and at least one of the two sides in contact with the side from which the electrode terminal is led out is the built-in seal portion. The exterior body having such a structure can more effectively obtain the effect of reducing dead space and improving pressure resistance by providing the built-in seal portion.

  The present invention also includes the outer package for an electrochemical device according to the present invention, a plurality of power generation elements and an electrolyte solution housed in a sealed state in the outer package, and one end connected to each electrode of the power generation element. An electrode terminal exposed at the other end of the exterior body, and the plurality of power generation elements are housed inside the exterior body with a partition wall between the power generation elements, and in series. An electrochemical device connected to the device is provided.

  Since such an electrochemical device includes the exterior body having the above-described structure, the dead space is sufficiently reduced and the pressure resistance is excellent, and a plurality of power generation elements connected in series are accommodated therein. Can increase the working voltage. Further, when a plurality of power generation elements are inserted into one exterior body, since the electrolyte solution between the power generation elements is made common, there is an advantage that it is easy to match the degree of deterioration of each power generation element.

  According to the present invention, a dead space can be sufficiently reduced, and an exterior body for an electrochemical device for accommodating a plurality of power generation elements having a seal structure excellent in pressure resistance, and electrochemical using the same A device can be provided.

It is a perspective view which shows suitable one Embodiment of the exterior body for electrochemical devices of this invention. It is a perspective view which shows an example of the conventional exterior body for electrochemical devices. It is a schematic cross section which shows an example of the basic composition of the laminate film used as the constituent material of the exterior body for electrochemical devices of this invention. FIG. 2 is a series of process diagrams when the electrochemical device exterior body 1 shown in FIG. 1 is produced. It is a front view which shows suitable one Embodiment of the electrochemical device (lithium ion secondary battery) of this invention. FIG. 6 is a development view showing the inside of the lithium ion secondary battery shown in FIG. 5. It is a schematic cross section at the time of cut | disconnecting the lithium ion secondary battery shown in FIG. 5 along the X1-X1 line | wire of FIG. It is a schematic cross section which shows the principal part at the time of cut | disconnecting the lithium ion secondary battery shown in FIG. 5 along the X2-X2 line | wire of FIG. It is a front view which shows other suitable one Embodiment of the electrochemical device (lithium ion secondary battery) of this invention. FIG. 10 is a development view showing the inside of the lithium ion secondary battery shown in FIG. 9.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a perspective view showing a preferred embodiment of an exterior body for an electrochemical device according to the present invention. As shown in FIG. 1, the exterior body 1 of this embodiment is disposed between a pair of laminated films 51 and 52 (first laminated film 51 and second laminated film 52) facing each other, and between them. It is comprised with the partition 7. In the exterior body 1, the seal portion formed by bonding the edges of the pair of laminate films 51 and 52 is bent toward the inner side of the exterior body so that the partition wall 7 is sandwiched between the edges of the pair of laminate films 51 and 52. The built-in seal part 5 accommodated in the exterior body is formed by being adhered in the state. The exterior body 1 can accommodate two power generation elements separated by a partition wall 7.

  The outer package 1 has a rectangular outer shape, and the pair of laminate films 51 and 52 are formed by bending a single laminate film. Further, in the exterior body 1, the side 1 </ b> A shown as the opening in FIG. 1 is a side leading to the electrode terminal, and the two sides 1 </ b> B and 1 </ b> C in contact with the side are both the built-in seal portion 5. . Further, the side 1D facing the side 1A of the exterior body 1 is a bent portion, and a pair of laminate films 51 and 52 are continuous. Therefore, the side 1D does not need a seal, and space saving is achieved.

  On the other hand, FIG. 2 is a perspective view showing an example of a conventional exterior body in which a seal portion sealed across the partition wall 9 is formed outside the exterior body. As shown in FIG. 2, in the conventional exterior body 8, the seal portion 6 formed by bonding the edges of the pair of laminate films 51 and 52 is provided outside the exterior body. In the exterior body 8, a side 8A shown as an opening in FIG. 2 is a side from which an electrode terminal is derived, and both the two sides 8B and 8C in contact with the side 8A and a side 8D facing the side 8A are sealed. It is part 6.

  In the structure of the exterior body 8 shown in FIG. 2, the seal part 6 becomes a dead space. On the other hand, according to the structure of the exterior body 1 shown in FIG. 1, since the seal part is the built-in seal part 5, the dead space can be sufficiently reduced.

  Further, in the structure of the exterior body 8 shown in FIG. 2, when the internal pressure inside the exterior body increases, a force is applied in the direction of the arrow P in FIG. Works and peels easily. On the other hand, according to the structure of the exterior body 1 shown in FIG. 1, when the internal pressure inside the exterior body increases, the force does not work in the direction in which the built-in seal portion 5 is pushed and spread. High pressure resistance can be obtained.

  Furthermore, in the structure of the exterior body 8 shown in FIG. 2, the sealant tends to protrude from the end of the seal portion 6 toward the outside of the exterior body during hot pressing. On the other hand, according to the structure of the exterior body 1 shown in FIG. 1, even if the sealant protrudes from the end of the built-in seal portion 5 during the hot press, the sealant protrudes toward the inside of the exterior body. Problems such as deterioration of the surface area, increase in dead space, breakage of the protruding portion and process failure due to dropping off are suppressed, and the operation of removing the protruding sealant is not required.

  As the pair of laminate films 51 and 52 (the first laminate film 51 and the second laminate film 52) constituting the exterior body 1 of the present embodiment, a laminate film having flexibility is used. Since the laminate film is lightweight and can be easily formed into a thin film, the electrochemical device itself can be formed into a thin film. Therefore, the original volume energy density can be easily improved, and the volume energy density based on the volume of the space in which the electrochemical device is to be installed can be easily improved.

  The laminate film is not particularly limited as long as it has flexibility, but it ensures the sufficient mechanical strength and light weight of the exterior body, while moisture and air enter the exterior body from the outside and the exterior. From the viewpoint of effectively preventing the diffusion of electrolyte components from the inside of the body to the outside, the polymer innermost layer that contacts the power generating element to be accommodated, and the side of the innermost layer that contacts the power generating element A laminate composed of three or more layers having at least a metal layer disposed on the opposite side of the metal layer and a polymer layer disposed on the opposite side of the metal layer in contact with the innermost layer. A film is preferred.

  As a laminated structure of a laminate film, for example, a laminate film having a configuration shown in FIG. The laminate film 53 shown in FIG. 3 has an innermost layer 53a made of a polymer that comes into contact with a power generation element housed inside the exterior body on the inner surface F1, and the other surface (outer surface) of the innermost layer 53a. It has a metal layer 53c disposed on top and a polymer outermost layer 53b disposed on the outer surface of the metal layer 53c.

  The innermost layer 53a is a flexible layer, and its constituent material can express the above-mentioned flexibility, and chemical stability with respect to the electrolyte solution accommodated in the exterior body. There is no particular limitation as long as it is a polymer having chemical stability against (chemical reaction, dissolution, and swelling) and oxygen and water (water in the air), but oxygen, water (air) A material having low permeability to the components of the water content and the electrolyte solution is preferable. Examples of the constituent material of the innermost layer 53a include engineering plastics and thermoplastic resins such as polyethylene, polypropylene, polyethylene acid modified products, polypropylene acid modified products, polyethylene ionomers, and polypropylene ionomers.

  The “engineering plastic” means a plastic having excellent mechanical properties, heat resistance, and durability used in mechanical parts, electrical parts, housing materials, etc., for example, polyacetal, polyamide, Examples include polycarbonate, polyoxytetramethyleneoxyterephthaloyl (polybutylene terephthalate), polyethylene terephthalate, polyimide, polyphenylene sulfide, and the like.

  Further, as the constituent material of the outermost layer 53b, the same constituent material as that of the innermost layer 53a may be used. In the exterior body of this embodiment, since the edge of the laminate film 53 is bent, the outer surfaces F2 of the laminate film 53 are bonded to each other in the built-in seal portion 5. Therefore, when the built-in seal portion 5 is formed by hot pressing, it is possible to selectively heat-seal the edge surfaces F2 by adjusting the heating temperature, so that the outermost layer 53b The constituent material is preferably a material having a lower melting point than that of the innermost layer 53a. Preferably, the constituent material of the outermost layer 53b includes polypropylene, polyethylene, nylon 6, nylon 11, nylon 12, polybutylene terephthalate (PBT), polyether ether ketone (PEEK), and the like. Among these, polypropylene and polyethylene are particularly preferable because of their extremely low water absorption.

  The metal layer 53c is preferably a layer formed of a metal material having corrosion resistance against oxygen, water (water in the air), and an electrolyte solution. For example, a metal foil made of aluminum, aluminum alloy, titanium, chromium, or the like may be used.

  As a laminate film used for the exterior body of the present embodiment, a laminate having a three-layer structure including an innermost layer 53a made of polyethylene terephthalate, a metal layer 53c made of aluminum, and an outermost layer 53b made of polypropylene. A film is particularly preferred.

  The laminate film 53 having the above-described structure can be produced by using a known production method such as a dry lamination method, a wet lamination method, a hot melt lamination method, or an extrusion lamination method. For example, a film to be a polymer layer constituting the laminate film 53 and a metal foil made of aluminum or the like are prepared. The metal foil can be prepared, for example, by rolling a metal material. Next, a laminate film (multilayer film) 53 is preferably formed by laminating a metal foil on the film to be a polymer layer via an adhesive so as to have a plurality of layers as described above. Is made. The obtained laminate film 53 is used after being cut into a predetermined shape and size.

  Examples of the constituent material of the partition wall 7 include polyethylene terephthalate, polypropylene, polyethylene, polymethyl methacrylate resin (acrylic resin), polyether ether ketone (PEEK), and the like. Among these, polyethylene terephthalate and polyethylene are preferable because of excellent adhesion to the first and second laminate films 51 and 52 and heat resistance. These materials can be formed into a film to form the partition wall 7.

  The partition wall 7 may be a porous film. It is preferable that the partition wall 7 is a porous film because the adhesive strength between the partition wall 7 in the built-in seal portion 5 and the edges 51B and 52B of the first and second laminate films 51 and 52 is improved. In addition, when the partition wall 7 is a porous film, the electrolyte solution easily goes back and forth between the accommodating portions that accommodate the respective power generation elements.

  Furthermore, holes may be formed in the partition wall 7 by punching or the like in portions sandwiched between the edge portions 51B and 52B of the first and second laminate films 51 and 52. A plurality of holes are preferably provided. The formation of the holes is preferable because the adhesive strength between the partition wall 7 and the edge portions 51B and 52B of the first and second laminate films 51 and 52 is improved. The partition wall 7 forming the hole may be a porous film or a non-porous film.

  Although the film thickness of the partition 7 is not specifically limited, It is preferable that it is 10-200 micrometers, and it is more preferable that it is 20-100 micrometers. If the film thickness is less than 10 μm, it tends to break during vacuum sealing, and if it exceeds 200 μm, the thickness of the element increases, and the flexibility of the partition walls is lost, which makes it difficult to widen the frontage when injecting. Tend to occur.

  Next, the example of the manufacturing method of the exterior body for electrochemical devices mentioned above is demonstrated. 4 (a) to 4 (d) are a series of process diagrams when manufacturing the exterior body 1 shown in FIG. First, as shown in FIG. 4A, a single laminate film 50 is prepared. The laminate film 50 is bent at a fold line YY in the drawing. The laminate film 50 has regions of a first laminate film 51 and a second laminate film 52 that are arranged to face each other when folded at a folding line YY.

  51B and 52B in the figure are edges of the first laminate film 51 and the second laminate film 52, respectively, and this part is bent, and the overlapping edges of the first and second laminate films 51 and 52 are shown. The built-in seal portion 5 is formed by bonding them together. Moreover, 51A and 52A in a figure show the partial area | region which does not form the built-in seal part 5 of the 1st laminate film 51 and the 2nd laminate film 52, respectively.

  Next, as shown in FIG. 4 (b), the edge portions 51 </ b> B and 52 </ b> B of the first and second laminate films 51 and 52 are bent to the side of the exterior body 1 that houses the power generation element. Thereafter, as shown in FIG. 4C, the partition wall 7 is disposed on the second laminate film 52. The partition wall 7 may be disposed on the first laminate film 51. Next, as shown in FIG. 4 (d), the laminate film 50 is folded in two at the fold line YY, and the edge portion 51B and the edge portion 52B are bonded together with the partition wall 7 interposed therebetween, so that the built-in seal portion 5 is formed. Thereby, the exterior body 1 can be produced. In the obtained exterior body 1, the power generation elements can be housed in the two housing portions separated by the partition wall 7.

  In the method for manufacturing the exterior body 1, the bonding method when bonding the edge portion 51 </ b> B and the edge portion 52 </ b> B with the partition wall 7 interposed therebetween is not particularly limited, but for example, a bonding method or an adhesive by heat sealing is used. The bonding method used can be used. From the viewpoint of productivity, it is preferable to use a heat seal method. In the case of bonding by the heat sealing method, for example, a method in which only a portion to which the edge portions 51B and 52B facing each other across the partition wall 7 are bonded by a thin blade can be hot pressed. Further, the laminate film 50 has a polymer innermost layer 53a, a metal layer 53c, and a polymer outermost layer 53b as shown in FIG. 3, and the constituent material of the outermost layer 53b. If the melting point of the innermost layer 53a is lower than the melting point of the constituent material, a part of the exterior body (the part forming the built-in seal portion 5) is formed from the outside of the first and second laminate films 51 and 52. It is also possible to use a method in which heat pressing is performed and only the edge portions 51B and the edge portions 52B facing each other across the partition wall 7 are selectively heat-sealed.

  As mentioned above, although the suitable embodiment of the exterior body for electrochemical devices of this invention was described in detail, the exterior body for electrochemical devices of this invention is not limited to the said embodiment. For example, in the exterior body 1 in the description of the above embodiment, all the seal portions other than the side from which the electrode terminal is led out are the built-in seal portions 5, but some of the seal portions are the built-in seal portions 5. The seal part may be a conventional seal part 6. Moreover, the exterior body of this invention is not limited to the rectangular shape shown in FIG.

  Moreover, in the exterior body 1 shown in FIG. 1, the partition 7 which has the planar shape substantially the same as the 1st and 2nd laminate films 51 and 52 is used, However, The shape of the partition 7 is electrically There is no particular limitation as long as the two power generating elements are separated from each other so as not to be connected. Therefore, the partition wall 7 may have a planar shape smaller than the first and second laminate films 51 and 52, and may have a shape that does not overlap with the seal portion on the side from which the electrode terminal is derived, for example. Further, the partition wall 7 may be fixed by being sandwiched only by one of the built-in seal portions 5.

  Furthermore, a plurality of partition walls 7 may be provided inside the exterior body. In that case, three or more accommodating portions are formed inside the exterior body, and three or more power generating elements can be accommodated.

  Further, in the outer package 1 shown in FIG. 1, the first and second laminate films 51 and 52 are formed by bending a single laminate film. A film different from the film 52 may be used. In this case, the bent portion in the exterior body 1 becomes a seal portion, but this seal portion can also be used as the built-in seal portion 5.

  Next, a preferred embodiment of an electrochemical device using the above-described electrochemical device exterior body will be described. In the present embodiment, a lithium ion secondary battery using the exterior body 1 shown in FIG. 1 as the exterior body will be described.

  FIG. 5 is a front view showing a preferred embodiment of the electrochemical device (lithium ion secondary battery) of the present invention. FIG. 6 is a development view showing the inside of the lithium ion secondary battery shown in FIG. FIG. 6 shows a state in which the partition wall 7 is partially broken. 7 is a schematic cross-sectional view of the lithium ion secondary battery shown in FIG. 5 cut along the line X1-X1 in FIG. 8 is a schematic cross-sectional view showing the main part when the lithium ion secondary battery shown in FIG. 5 is cut along the line X2-X2 of FIG.

  As shown in FIG. 5 to FIG. 8, the lithium ion secondary battery 100 is mainly disposed adjacent to the plate-like negative electrode 10 and the plate-like positive electrode 20 facing each other and between the negative electrode 10 and the positive electrode 20. The first and second power generation elements 61 and 62 configured by the plate-shaped separator 40, the lead 30 that connects the first power generation element 61 and the second power generation element 62 in series, and lithium ions The electrolyte solution containing, the exterior body 1 that contains them in a sealed state, and one end portion is electrically connected to the positive electrode 20 of the first power generation element 61 and the other end portion is outside the exterior body 1. And the negative electrode lead 12 whose one end is electrically connected to the negative electrode 10 of the second power generation element 62 and whose other end protrudes outside the exterior body 1. It consists of and. Hereinafter, details of each component of this embodiment will be described.

  In the present specification, the “negative electrode” is an electrode based on the polarity at the time of discharge of the battery and emits electrons by an oxidation reaction at the time of discharge. Further, the “positive electrode” is an electrode based on the polarity at the time of discharging of the battery and accepts electrons by a reduction reaction at the time of discharging.

  First, the negative electrode 10 and the positive electrode 20 will be described. The negative electrode 10 includes a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector. The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector.

  The negative electrode current collector and the positive electrode current collector are not particularly limited as long as they are good conductors that can sufficiently transfer charges to the negative electrode active material-containing layer and the positive electrode active material-containing layer, and are known lithium ion secondary batteries. The current collector used in the above can be used. For example, the negative electrode current collector and the positive electrode current collector include metal foils such as copper and aluminum, respectively.

  The negative electrode active material-containing layer of the negative electrode 10 is mainly composed of a negative electrode active material and a binder. Note that the negative electrode active material-containing layer preferably further contains a conductive additive.

The negative electrode active material is occlusion and release of lithium ions, desorption and insertion (intercalation) of lithium ions, or doping with lithium ions and counter anions of the lithium ions (for example, PF ₆ ⁻ , ClO ₄ ⁻ ). Any known negative electrode active material can be used without particular limitation as long as it can reversibly proceed with undoping. As such a negative electrode active material, for example, it can be combined with a carbon material such as natural graphite, artificial graphite, non-graphitizable carbon, graphitizable carbon, low-temperature calcined carbon, or lithium such as Al, Si, or Sn. Examples thereof include amorphous compounds mainly composed of oxides such as metals, SiO, SiO ₂ , SiO _x , and SnO ₂ , lithium titanate (Li ₄ Ti ₅ O ₁₂ ), and TiO ₂ .

  As the binder used for the negative electrode 10, known binders can be used without particular limitation. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene. Copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer Examples thereof include fluororesins such as a polymer (ECTFE) and polyvinyl fluoride (PVF). This binder not only binds constituent materials such as active material particles and conductive assistants added as necessary, but also contributes to binding between the constituent materials and the current collector. Yes.

  In addition to the above, as the binder, for example, vinylidene fluoride-based fluororubber such as vinylidene fluoride-hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber) may be used.

  In addition to the above, as the binder, for example, polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, cellulose, styrene / butadiene rubber, isoprene rubber, butadiene rubber, ethylene / propylene rubber and the like may be used. Also, thermoplastic elastomeric polymers such as styrene / butadiene / styrene block copolymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers, and hydrogenated products thereof. May be used. Further, syndiotactic 1,2-polybutadiene, ethylene / vinyl acetate copolymer, propylene / α-olefin (carbon number 2 to 12) copolymer and the like may be used. Further, a conductive polymer may be used.

  It does not specifically limit as a conductive support agent used as needed, A well-known conductive support agent can be used. Examples thereof include carbon blacks, carbon materials, metal powders such as copper, nickel, stainless steel, and iron, mixtures of carbon materials and metal powders, and conductive oxides such as ITO.

  The positive electrode active material-containing layer of the positive electrode 20 is mainly composed of a positive electrode active material and a binder. Note that the positive electrode active material-containing layer preferably further contains a conductive additive.

The positive electrode active material includes insertion and extraction of lithium ions, desorption and insertion of lithium ions (intercalation), or doping and dedoping of lithium ions and a counter anion (for example, ClO ₄ ⁻ ) of the lithium ions. If it can be made to advance reversibly, it will not specifically limit, A well-known electrode active material can be used. For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganese spinel (LiMn ₂ O ₄ ), and the general formula: LiNi _x Co _y Mn _z M _a O ₂ (x + y + z + a = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, 0 ≦ a ≦ 1, and M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, and Cr) Complex metal oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMPO ₄ (where M is one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr) Or a composite metal oxide such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ).

  As the binder used for the positive electrode 20, the same binder as that used for the negative electrode 10 can be used. Moreover, as a conductive support agent used for the positive electrode 20 as needed, the same conductive support agent used for the negative electrode 10 can be used.

  The positive electrode current collector of the positive electrode 20 is electrically connected to one end of a positive electrode lead 22 made of, for example, aluminum, and the other end of the positive electrode lead 22 extends to the outside of the exterior body 1. On the other hand, the negative electrode current collector of the negative electrode 10 is also electrically connected to one end of a negative electrode lead 12 made of, for example, copper or nickel, and the other end of the negative electrode lead 12 extends to the outside of the exterior body 1.

  The separator 40 disposed between the negative electrode 10 and the positive electrode 20 is not particularly limited as long as it is formed of a porous body having ion permeability and electronic insulation properties, and is a known lithium ion secondary. The separator used for a battery can be used. For example, a laminate of a film made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above polymers, or a fiber nonwoven fabric made of at least one constituent material selected from the group consisting of cellulose, polyester and polypropylene, etc. It is done.

An electrolyte solution (not shown) is filled in the internal space of the outer package 1, and a part of the electrolyte solution is contained in the negative electrode 10, the positive electrode 20, and the separator 40. As the electrolyte solution, a non-aqueous electrolyte solution in which a lithium salt is dissolved in an organic solvent is used. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CF ₂ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN Salts such as (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiN (CF ₃ CF ₂ CO) ₂ are used. In addition, these salts may be used individually by 1 type, and may use 2 or more types together. Further, the electrolyte solution may be gelled by adding a polymer or the like.

  Moreover, the solvent currently used for the well-known electrochemical device can be used for an organic solvent. For example, propylene carbonate, ethylene carbonate, diethyl carbonate and the like are preferable. These may be used alone or in combination of two or more at any ratio.

  The exterior body 1 has the structure shown in FIGS. 1 and 4, and a seal portion other than the side from which the electrode terminal is led out is a built-in seal portion 5. Further, as shown in FIGS. 5 and 6, the edges 51a and 52a of the first laminate film 51 and the second laminate film 52 where the built-in seal portion 5 is not formed are electrode terminals (the negative electrode lead 12 and the positive electrode). The lead 22) and the partition wall 7 are sealed. The negative electrode lead 12 and the first and second laminated films are in the portion of the negative electrode lead 12 that contacts the edge portion 51a of the first laminate film 51 and the seal portion of the edge portion 52a of the second laminate film 52. An insulator 14 for preventing contact with the metal layer is coated. Further, the positive electrode lead 22 and the first and second laminates are formed on the positive electrode lead 22 portion that contacts the seal portion of the edge portion 51 a of the first laminate film 51 and the edge portion 52 a of the second laminate film 52. An insulator 24 for preventing contact with the metal layer in the film is coated.

  The configurations of the insulator 14 and the insulator 24 are not particularly limited, but may be formed of, for example, a polymer. Note that the insulator 14 and the insulator 24 may not be disposed as long as the metal layer in the laminate film can be sufficiently prevented from contacting each of the negative electrode lead 12 and the positive electrode lead 22.

  Inside the exterior body 1, two power generation elements (a first power generation element 61 and a second power generation element 62) are accommodated with the partition wall 7 interposed therebetween. These first and second power generation elements 61 and 62 are separated by a partition wall 7 so as not to be in direct contact with each other, and are connected in series via a lead 30 inside the exterior body 1 as shown in FIG. . The lead 30 is passed through a gap between the partition wall 7 and the bent portion of the laminate film 50.

  Next, a method for manufacturing the above-described lithium ion secondary battery 100 will be described.

  The manufacturing method of the first and second power generation elements 61 and 62 (a laminated body in which the negative electrode 10, the separator 40, and the positive electrode 20 are sequentially laminated in this order) is not particularly limited, and is a known lithium ion secondary battery. A publicly known method adopted for production can be used.

  When the negative electrode 10 and the positive electrode 20 are produced, first, the above-described constituent components are mixed and dispersed in a solvent in which the binder can be dissolved to produce an electrode-forming coating solution (slurry or paste). The solvent is not particularly limited as long as the binder can be dissolved. For example, N-methyl-2-pyrrolidone, N, N-dimethylformamide and the like can be used.

  Next, the electrode forming coating solution is applied onto the surface of the current collector, dried, and rolled to form an active material-containing layer on the current collector, thereby completing the production of the negative electrode 10 and the positive electrode 20. Here, the method for applying the electrode-forming coating solution to the surface of the current collector is not particularly limited, and may be appropriately determined according to the material, shape, and the like of the current collector. Examples of the coating method include a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, and a screen printing method.

  Thereafter, the negative electrode lead 12 is electrically connected to the negative electrode 10 of the second power generation element 62, and the positive electrode lead 22 is electrically connected to the positive electrode 20 of the first power generation element 61.

  Next, the separator 40 is disposed between the negative electrode 10 and the positive electrode 20 in a contacted state (preferably in a non-adhered state), and the first and second power generation elements 61 and 62 are completed. At this time, it arrange | positions so that the surface by the side of the negative electrode active material content layer of the negative electrode 10 and the surface by the side of the positive electrode active material content layer of the positive electrode 20 may contact with the separator 40.

  Thereafter, the negative electrode 10 of the first power generation element 61 and the positive electrode 20 of the second power generation element 62 are electrically connected by the lead 30. The material of the lead 30 is not particularly limited as long as it has conductivity. For example, the same material as the current collector of each electrode, the negative electrode lead 12 and the positive electrode lead 22 is used. Further, the lead 30 may be configured by extending a part of either the negative electrode current collector of the first power generation element 61 or the positive electrode current collector of the second power generation element 62. .

  On the other hand, the exterior body 1 is manufactured by the manufacturing method described above. Here, when the first power generation element 61 and the second power generation element 62 are connected by the lead 30 as shown in FIG. 6, it is inserted into the exterior body 1 after the exterior body 1 is manufactured. Have difficulty. Therefore, it is preferable that the production of the exterior body 1 and the insertion of the first and second power generation elements 61 and 62 connected by the lead 30 are performed in parallel. That is, the first and second power generation elements 61 and 62 connected by the lead 30 are disposed on the laminate film 50, the partition wall 7 is disposed between the power generation elements 61 and 62, and then the laminate film 50 is bent. It is preferable to form the exterior body 1 in which the first and second power generation elements 61 and 62 are inserted by bending at Y-Y and sealing the edges. When the lead 30 is provided on the same side as the negative electrode lead 12 and the positive electrode lead 22, the first and second power generation elements 61 and 62 connected by the lead 30 are inserted after the exterior body 1 is manufactured. It is also possible to do.

  Next, an electrolyte solution is injected into the inside from the opening of the outer package 1. Subsequently, in a state where a part of the negative electrode lead 12 and the positive electrode lead 22 are respectively inserted into the outer package 1, the opening of the outer package 1 is sealed using a sealing machine. Thereby, the production of the lithium ion secondary battery 100 is completed.

  In the above-described embodiment, the case where each power generation element is connected by the lead 30 inside the exterior body has been shown. However, the power generation element may be connected by providing a lead for series connection outside the exterior body. In this case, it is not necessary to perform the production of the exterior body 1 and the insertion of the first and second power generation elements 61 and 62 connected by the lead 30 in parallel as described above. Further, when connecting and connecting a lead for series connection outside the exterior body, it is possible to connect a balance circuit and a protection circuit to the lead. Hereinafter, a lithium ion secondary battery having such a structure will be described.

  FIG. 9 is a front view showing another preferred embodiment of the electrochemical device (lithium ion secondary battery) of the present invention. FIG. 10 is a development view showing the inside of the lithium ion secondary battery shown in FIG. FIG. 10 shows a state in which the partition wall 7 is partially broken.

  As shown in FIGS. 9 and 10, the lithium ion secondary battery 200 includes a first and second power generation elements 61 and 62, an electrolyte solution containing lithium ions, and an outer package 1 that contains these in a sealed state. The negative electrode lead 16 and the positive electrode lead 22 that are electrically connected to the negative electrode 10 and the positive electrode 20 of the first power generation element 61 and led out of the exterior body 1, and the second power generation element 62. The negative electrode lead 12 and the positive electrode lead 26 are electrically connected to the negative electrode 10 and the positive electrode 20, respectively, and led out to the outside of the outer package 1. The negative electrode lead 16 and the positive electrode lead 26 are leads for connecting the power generation elements in series. By connecting the negative electrode lead 16 and the positive electrode lead 26 electrically, the first power generation element 61 and the second power generation element 62 are connected in series. Also, each of the negative electrode lead 12, the negative electrode lead 16, the positive electrode lead 22, and the positive electrode lead 26 that are in contact with the seal portion of the edge portion 51 a of the first laminate film 51 and the edge portion 52 a of the second laminate film 52. The portions are covered with an insulator 14, an insulator 18, an insulator 24, and an insulator 28, respectively. The configuration of the negative electrode lead 16 is the same as that of the negative electrode lead 12, the configuration of the positive electrode lead 26 is the same as that of the positive electrode lead 22, and the configurations of the insulators 18 and 28 are the same as those of the insulators 14 and 24. is there.

  In the lithium ion secondary battery 200, a balance circuit and a protection circuit can be connected between the negative electrode lead 16 and the positive electrode lead 26 to be connected. Thereby, damage to the element due to overcharging and deterioration of electrical characteristics due to overdischarge can be prevented, and the reliability of the element can be improved.

  Further, when manufacturing the lithium ion secondary battery 200, the first and second power generating elements 61 and 62 can be inserted into the exterior body 1 after the exterior body 1 having an opening is manufactured. The connection between the negative electrode lead 16 of the first power generation element 61 and the positive electrode lead 26 of the second power generation element 62 may be performed before or after the power generation element is inserted into the exterior body 1. Good.

  As mentioned above, although the suitable embodiment of the electrochemical device of this invention was described in detail, this invention is not limited to the said embodiment. For example, in the description of the above embodiment, the lithium ion secondary batteries 100 and 200 each including the negative electrode 10 and the positive electrode 20 have been described. However, the negative electrode 10 and the positive electrode are each provided with two or more negative electrodes 10 and 20. 20 may be configured such that one separator 40 is always disposed between the two. Further, the exterior body may have a structure in which each accommodating portion is completely partitioned by the partition wall 7 so that the electrolyte solution cannot pass between the accommodating portions that accommodate the respective power generation elements.

  In the description of the above embodiment, the case where the exterior body 1 shown in FIG. 1 is used as the exterior body has been described, but an exterior body in which the shape of the partition wall 7 is changed as described above may be used. Moreover, the electrochemical device (lithium ion secondary battery) of this invention is good also as a structure which provided the some partition 7 and accommodated the 3 or more electric power generation element. Furthermore, the electrochemical device (lithium ion secondary battery) of the present invention is not limited to the shape shown in FIG.

  In the description of the above embodiment, the case where the electrochemical device is a lithium ion secondary battery has been described. However, the electrochemical device of the present invention is not limited to a lithium ion secondary battery, and a metallic lithium secondary battery. Secondary batteries other than lithium ion secondary batteries such as batteries, and electrochemical capacitors such as electric double layer capacitors, pseudo-capacitance capacitors, pseudo capacitors, and redox capacitors may be used. In the case of an electrochemical device other than a lithium ion secondary battery, a material suitable for each electrochemical device may be used as the electrode active material. For example, in the case of an electric double layer capacitor, acetylene black, graphite, graphite, activated carbon, or the like is used as an active material contained in the positive electrode active material-containing layer and the negative electrode active material-containing layer.

DESCRIPTION OF SYMBOLS 1 ... Electrochemical device exterior body, 5 ... Built-in seal part, 7 ... Partition, 10 ... Negative electrode, 12 ... Negative electrode lead, 14 ... Insulator, 16 ... Negative electrode lead, 18 ... Insulator, 20 ... Positive electrode, 22 ... Lead for positive electrode, 24 ... Insulator, 26 ... Lead for positive electrode, 28 ... Insulator, 30 ... Lead, 40 ... Separator, 50 ... Laminate film, 51 ... First laminate film, 52 ... Second laminate film, 61 ... 1st electric power generation element, 62 ... 2nd electric power generation element, 100,200 ... Lithium ion secondary battery.

Claims (3)

An exterior body for accommodating a plurality of power generation elements of an electrochemical device in a state where a partition wall is sandwiched between the power generation elements,
It is composed of a pair of laminated films facing each other and the partition wall,
Having a seal portion formed by bonding the edges of the pair of laminate films with the partition interposed therebetween,
At least a part of the seal part is a built-in seal part accommodated inside the exterior body by bending and bonding the edges of the pair of laminate films to the inside of the exterior body. Device exterior. The outer shape is rectangular,
The exterior body for an electrochemical device according to claim 1, wherein at least one of two sides in contact with a side from which the electrode terminal is led out serves as the built-in seal portion. The exterior body for an electrochemical device according to claim 1 or 2,
A plurality of power generation elements and electrolyte solution housed in a sealed state in the exterior body;
One end is connected to each electrode of the power generation element, and the other end is exposed to the outside of the exterior body,
A plurality of the power generation elements are accommodated in the exterior body with a partition wall interposed between the power generation elements, and are connected in series.

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