JP2010161249A - Lithium ion capacitor - Google Patents

Abstract

An object of the present invention is to provide a lithium ion capacitor capable of efficiently producing an electrode group composed of a positive electrode, a negative electrode and a separator in a short time and having a structure suitable for achieving high output.
An electrode group 11 of a lithium ion capacitor is formed by using a strip-like positive electrode 21, a strip-like separator 41, and a flat plate-like plurality of negative electrodes 31 without bending. In the electrode group 11, the belt-like positive electrode 21 and the belt-like separator 41 are overlapped and wound into a flat roll shape, and a flat plate-like negative electrode 31 is interposed between the flat portions of the wound positive electrode 21 via the separator 41. It has a sandwiched structure.
[Selection] Figure 3

Description

  The present invention relates to a lithium ion capacitor including an electrode group including a positive electrode, a negative electrode, and a separator.

  Energy storage systems such as load leveling devices such as photovoltaic power generation and wind power generation, instantaneous voltage drop countermeasure devices for electronic devices such as computers, and energy regeneration devices for electric vehicles and hybrid cars have a large energy capacity. There is a need for an electricity storage device that can be rapidly charged and discharged. Conventional lead-acid batteries and other secondary batteries are difficult to charge and discharge with a large current and have a short cycle life, so it is difficult to cope with the power storage system. Accordingly, in recent years, non-aqueous power storage devices have attracted attention as new power storage devices that can solve these problems.

  Currently, a lithium ion capacitor has been proposed as an electric storage device capable of rapid charging / discharging and extending the life (see Patent Document 1). As this lithium ion capacitor, there are known a wound type configured by winding electrodes in a roll shape and a stacked type configured by stacking plate-shaped electrodes. For this purpose, a multilayer type capacitor is used.

  In the laminated type lithium ion capacitor, as shown in FIGS. 15 and 16, a plate-like positive electrode 61, negative electrode 62, and separator 63 are used, and the positive electrode 61 and the negative electrode 62 are alternately laminated via the separator 63. Thus, the electrode group 65 is formed.

JP 2006-12702 A

  By the way, in the laminated type lithium ion capacitor, since it is necessary to form the electrode group 65 by stacking the electrodes 61 and 62 and the separator 63 one by one, the forming process becomes complicated and takes time. Specifically, when the stacked electrode group 65 is formed, it takes three times or more time as compared with the wound type.

  On the other hand, a wound-type lithium ion capacitor is highly productive, but has a structure in which an external terminal is connected to the end of a cylindrical electrode group for current collection, resulting in high electrical resistance and high output. It is unsuitable. Furthermore, when the electrode group has a cylindrical shape, there is a problem that it is difficult to connect an external terminal.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide lithium having a structure suitable for achieving a high output while efficiently producing an electrode group composed of a positive electrode, a negative electrode and a separator in a short time. It is to provide an ion capacitor.

  In order to solve the above-mentioned problems, the invention described in means 1 includes a container, a positive electrode having a structure in which a positive electrode made of a carbon material is formed on a positive electrode current collector, and a material capable of inserting and extracting lithium. A negative electrode having a structure in which a negative electrode is formed on a negative electrode current collector, and a separator interposed between the positive electrode and the negative electrode, and an electrode group including the positive electrode, the negative electrode, and the separator is housed together with an electrolyte A positive electrode external terminal connected to the positive electrode current collector and a negative electrode external terminal connected to the negative electrode current collector are both extracted from the container. In the lithium ion capacitor, the electrode group uses a strip-shaped positive electrode, a strip-shaped separator, and a flat plate and a plurality of negative electrodes without bending, and the strip-shaped positive electrode and It has a structure in which a strip-shaped separator is overlapped and wound in a flat roll shape or folded in a bellows shape, and the negative electrode is sandwiched between the flat portions of the positive electrode in a wound or folded state through the separator. The gist of the feature is a lithium ion capacitor.

  According to the invention described in Means 1, since the electrode group is formed by overlapping the belt-like positive electrode and the belt-like separator and winding them into a flat roll shape or folding them into a bellows shape, the positive electrodes and the separators are formed one by one. The formation process can be simplified as compared with the case where the electrode group is formed by overlapping. In addition, since a plurality of flat plate-like negative electrodes are sandwiched in the electrode group, the negative electrode is bent when the belt-like positive electrode and the belt-like separator are overlapped and wound into a flat roll shape or folded into a bellows shape. Can be prevented. Here, when the negative electrode is bent and partially thinned, current concentration occurs in the thinned portion and lithium metal is likely to be deposited, but in this case, achievement of high output is hindered. On the other hand, in the present invention, each negative electrode is flat and has a uniform thickness, so that current concentration hardly occurs and precipitation of lithium metal can be avoided. In addition, the external electrode can be easily connected to the flat portion of the positive electrode and the flat negative electrode constituting the electrode group. Furthermore, since the electrode group has a structure in which positive electrodes and negative electrodes are alternately stacked via separators, a capacitor excellent in rapid charge / discharge can be realized. Also, unlike the conventional cylindrical roll shape, the electrode group has a flat roll shape or a bellows shape, so that it can be pressurized in the thickness direction of the electrode group, which also contributes to higher output. Yes.

  The invention described in means 2 includes a container, a positive electrode having a structure in which a positive electrode made of a carbon material is formed on a positive electrode current collector, and a negative electrode made of a material capable of occluding and releasing lithium. A negative electrode having a structure formed above, and a separator interposed between the positive electrode and the negative electrode, and an electrode group including the positive electrode, the negative electrode, and the separator is housed in the container together with an electrolyte, In the lithium ion capacitor that is preliminarily doped with lithium ions and has a positive electrode external terminal connected to the positive electrode current collector and a negative electrode external terminal connected to the negative electrode current collector drawn from the container, the electrode A group consists of a belt-like positive electrode, a belt-like separator, and a belt-like negative electrode, which are wound into a flat roll or folded into a bellows, and wound or folded. While leaving the negative electrode located between the normal parts of the positive electrode in the state of being in a state, the positive and negative electrodes other than the flat part are previously removed from each current collector, and the electrode area of the positive electrode is made smaller than the electrode area of the negative electrode, The gist is a lithium ion capacitor having a structure in which the outer periphery of the positive electrode is inside the outer periphery of the negative electrode.

  According to the invention described in Means 2, since the electrode group is formed by stacking the belt-like positive electrode, the belt-like separator, and the belt-like negative electrode in a flat roll shape or folding in a bellows shape, the positive electrode, the separator, and The formation process can be simplified as compared with the case where the electrode group is formed by stacking the negative electrodes one by one. Moreover, the negative electrode which comprises an electrode group leaves the negative electrode located between the flat parts of a positive electrode, and positive / negative electrodes other than a flat part are previously removed from on the electrical power collector. Even in this configuration, since the negative electrode area is larger than the positive electrode area and the outer periphery of the negative electrode is outside the outer periphery of the positive electrode, current concentration is unlikely to occur in each negative electrode, which hinders high output. It is possible to avoid the deposition of lithium metal which is the cause. In addition, the external electrodes can be easily connected to the positive electrode normal portion and the negative electrode normal portion constituting the electrode group. Furthermore, since the electrode group has a structure in which positive electrodes and negative electrodes are alternately stacked via separators, a capacitor excellent in rapid charge / discharge can be realized. Also, unlike the conventional cylindrical roll shape, the electrode group has a flat roll shape or a bellows shape, so that it can be pressurized in the thickness direction of the electrode group, which also contributes to higher output. Yes.

  The gist of the invention described in means 3 is that, in means 1 or 2, at least the negative electrode current collector of the positive electrode current collector and the negative electrode current collector is a porous body.

  According to the invention described in the means 3, since the negative electrode current collector is a porous body, the negative electrode can be pre-doped with lithium ions efficiently. Further, when the positive electrode current collector is made porous in addition to the negative electrode current collector, the degree of freedom of arrangement of the pre-doping lithium metal is increased, so that lithium ions can be pre-doped efficiently.

  The gist of the invention described in Means 4 is that, in any one of Means 1 to 3, the positive electrode and the separator are partially cut at a location excluding the layered portion in the electrode group.

  According to the invention described in the means 4, it is possible to efficiently dope lithium ions through the cut portion by partially cutting the electrode group.

  As described above in detail, according to the invention described in claims 1 to 4, lithium having an electrode group composed of a positive electrode, a negative electrode, and a separator can be efficiently produced in a short time, and has a structure suitable for achieving high output. An ion capacitor can be provided.

The side view which shows the lithium ion capacitor of 1st Embodiment. The top view which shows the lithium ion capacitor of 1st Embodiment. Sectional drawing which shows the electrode group of 1st Embodiment. Sectional drawing in the AA in the electrode group of FIG. The top view which shows a positive electrode, a negative electrode, and a separator. The perspective view which shows a positive electrode, a negative electrode, and a separator. (A)-(c) is explanatory drawing which shows the manufacturing method of the electrode group of 1st Embodiment. Sectional drawing which shows the electrode group of 2nd Embodiment. (A)-(c) is explanatory drawing which shows the manufacturing method of the electrode group of 2nd Embodiment. The perspective view which shows the positive electrode of another embodiment, a negative electrode, and a separator. The perspective view which shows the positive electrode of another embodiment, a negative electrode, and a separator. The perspective view which shows the positive electrode of another embodiment, a negative electrode, and a separator. The perspective view which shows the positive electrode of another embodiment, a negative electrode, and a separator. Sectional drawing which shows the electrode group of another embodiment. The top view which shows the conventional positive electrode, the negative electrode, and a separator. The top view which shows the conventional electrode group.

[First Embodiment]

  Hereinafter, a first embodiment in which the present invention is embodied in a lithium pre-doped lithium ion capacitor will be described in detail with reference to the drawings. FIG. 1 is a side view showing a lithium ion capacitor 10 according to the present embodiment, and FIG. 2 is a plan view of the lithium ion capacitor 10. 3 is a sectional view showing the electrode group 11 constituting the lithium ion capacitor 10, and FIG. 4 is a sectional view taken along the line AA in the electrode group 11 of FIG. FIG. 5 is a plan view showing the positive electrode 21, the negative electrode 31, and the separator 41 that constitute the electrode group 11.

  As shown in FIGS. 1 to 5, the lithium ion capacitor 10 of the present embodiment includes an electrode group 11 including a positive electrode 21, a negative electrode 31, and a separator 41 interposed between the positive electrode 21 and the negative electrode 31. . In the electrode group 11 of the present embodiment, the belt-like positive electrode 21 and the belt-like separator 41 are overlapped and wound into a flat roll shape, and a flat plate is interposed between the flat portions of the wound positive electrode 21 via the separator 41. The negative electrode 31 is sandwiched. The electrode group 11 is hermetically housed in the container 51 (housing body) together with the electrolyte.

  The belt-like positive electrode 21 has a structure in which a positive electrode 22 made of a carbon material is formed on a positive electrode current collector 23 (see FIG. 5). In the present embodiment, the positive electrode 22 is coated on the belt-like positive electrode current collector 23 in a planar shape with one end portion left in a line shape along the longitudinal direction.

  Examples of the carbon material forming the positive electrode 22 include graphite materials such as various natural graphites, synthetic graphites, and expanded graphites that have been appropriately pulverized, carbonized mesocarbon microbeads, and mesophase pitch carbon. Examples thereof include synthetic graphite materials obtained by graphitizing carbon materials such as fibers, vapor-grown carbon fibers, pyrolytic carbon, petroleum coke, pitch coke, and needle coke, or a mixture thereof. These carbon materials are kneaded and molded together with a conductive agent and a binder as necessary.

  Examples of the conductive agent include various graphite materials and carbon black. Among them, it is preferable to use conductive carbon blacks. Specific examples include channel black, oil furnace black, lamp black, thermal black, acetylene black, ketjen black, etc., but it is possible to select acetylene black in terms of excellent liquid retention and low electrical resistance. Particularly preferred.

  The binder is not particularly limited as long as it is insoluble in the organic electrolyte. For example, a fluorine-based resin such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF), or carboxymethylcellulose. Organic polymer compounds such as alkali metal salts or ammonium salts, polyimide resins, polyamide resins, polyacrylic acid and sodium polyacrylate are suitable.

  The positive electrode current collector 23 is a member for collecting current while supporting the positive electrode 22. For example, a conductive metal foil such as aluminum or stainless steel or a conductive metal plate is preferably used. Stainless steel is a suitable material in that it is not alloyed with lithium and is less susceptible to electrochemical oxidation.

  In the electrode group 11 wound in a flat roll shape, one end portion (the end portion where the positive electrode 22 is not coated) of the positive electrode current collector 23 protrudes from the wound portion of the separator 41. A positive electrode external terminal 25 made of a conductive metal material is joined to one end of the positive electrode current collector 23 by welding.

  The negative electrode 31 has a structure in which a negative electrode 32 made of a material capable of inserting and extracting lithium ions is formed on a negative electrode current collector 33. In the present embodiment, the negative electrode 32 is coated on the flat negative electrode current collector 33 in a planar shape with one end left. In addition, as a metal which supplies lithium ion, not only a lithium metal single-piece | unit is pointed out, but the substance which contains lithium at least and can supply lithium ion like a lithium-aluminum alloy is widely pointed out. .

Specific examples of the material for forming the negative electrode 32 include lithium metal, lithium-aluminum alloy, graphite material, graphitizable carbon material, non-graphitizable carbon material, niobium pentoxide (Nb ₂ O ₅ ), lithium titanate. (Li ₄ Ti ₅ O ₁₂ ), silicon monoxide (SiO), tin monoxide (SnO), composite oxide of tin and lithium (Li ₂ SnO ₃ ), composite oxide of lithium, phosphorus and boron (for example, LiP _0.4 B _0.6 O _2.9 ), etc. Among these, carbon materials such as graphite materials, graphitizable carbon materials, and non-graphitizable carbon materials are suitable as negative electrode materials because they have properties such as high reversibility.

  Examples of the carbon material that forms the negative electrode 32 include various natural graphites that have been appropriately pulverized, graphite materials such as synthetic graphite, expanded graphite, mesocarbon microbeads that have been carbonized, and mesophase pitch-based carbon. Examples thereof include carbon materials such as fibers, vapor-grown carbon fibers, pyrolytic carbon, petroleum coke, pitch coke, and needle coke, or a mixture thereof. The carbon materials for the negative electrode 32 listed here are kneaded and molded together with a conductive agent and a binder as necessary. As the conductive agent and the binder, the materials exemplified in the description of the positive electrode 22 can be used as they are.

  The negative electrode current collector 33 is a member for collecting current while supporting the negative electrode 32. For example, a conductive metal foil such as copper, nickel, stainless steel, or a conductive metal plate is preferably used. In addition, when a porous body is used as the negative electrode current collector 33, it is possible to increase the efficiency of lithium ion pre-doping.

  In the electrode group 11 wound in a flat roll shape, one end portion (an end portion where the negative electrode 32 is not coated) of the negative electrode current collector 33 protrudes from the wound portion of the separator 41. A negative electrode external terminal 35 made of a conductive metal material is joined to one end of the negative electrode current collector 33 by welding.

  In addition, a lithium application part (not shown) is provided in a predetermined part (for example, upper and lower parts on the external terminal side) of the electrode group 11, and a lithium metal foil (not shown) for pre-doping is provided on the lithium application part. (Omitted) is affixed. The lithium metal foil dissolves and disappears when the pre-doping is completed.

  In the electrode group 11 of the present embodiment, the area of the flat portion of the positive electrode 21 is larger than the area of the negative electrode 31 when viewed from the thickness direction of the electrode group 11 (that is, in plan view). The reason for such a size is to avoid precipitation of lithium metal due to current concentration.

  The separator 41 interposed between the negative electrode 31 and the positive electrode 21 is durable to an organic electrolyte, an electrode active material, and the like, and is made of a non-conductive porous body having continuous air holes. Usually, a cloth, a nonwoven fabric or a porous body made of glass fiber, polyethylene, polypropylene or the like is used. The thickness of the separator 41 is preferably thin in order to reduce the internal resistance of the capacitor, but can be appropriately set in consideration of the amount of organic electrolyte retained, flowability, strength, and the like.

The separator 41 is usually impregnated with a liquid organic electrolyte, but a gel or solid organic electrolyte may be used to prevent leakage. Here, the organic electrolyte is obtained by dissolving a compound capable of generating a doped lithium ion in an aprotic organic solvent. Examples of the compound include organic lithium salts. Preferred examples thereof include lithium hexafluorophosphate represented as LiPF ₆ and lithium bis (trifluoromethanesulfone) represented as LiN (CF ₃ SO ₂ ) _2. Examples include imide and lithium bis (pentafluoroethanesulfone) imide represented by LiN (C ₂ F ₅ SO ₂ ) ₂ . Moreover, as a suitable example of the said aprotic organic solvent, propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), (gamma) -butyrolactone (GBL), vinylene carbonate (VC), acetonitrile (AN), for example ), Dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and derivatives thereof, or a mixed solvent thereof.

  The container 51 of the lithium ion capacitor 10 is a soft container processed into a rectangular bag shape using an aluminum laminate film obtained by laminating an aluminum foil on a resin film. The opening is sealed by heat sealing. Sealing by thermal fusion is performed in a state where the positive electrode external terminal 25 and the negative electrode external terminal 35 are sandwiched between the fusion portions.

  When the electrode group 11 is housed in the container 51 in this way, the positive electrode external terminal 25 is drawn out from one end (the right end in FIG. 1) of the container 51 and the other end (in FIG. 1). The negative external terminal 35 is pulled out from the left end). In addition, you may form the container 51 using the metal laminate film material which consists of metal foil other than aluminum foil.

  Next, a method for manufacturing the above-described lithium ion capacitor 10 will be described.

  First, a belt-like positive electrode 21, a belt-like separator 41, and a flat plate-like negative electrode 31 without bending are prepared (see FIG. 5).

  The positive electrode 21 is produced by the following procedure. First, a mixed slurry containing a carbon material, a conductive agent and a binder is prepared, and this is applied to an aluminum foil having a thickness of 20 μm which is the positive electrode current collector 23 to form the positive electrode 22. After drying and pressing the positive electrode 22, the positive electrode 22 is cut into a predetermined size with a mold to obtain a belt-like positive electrode 21. The negative electrode 31 is produced by the following procedure. First, a mixed slurry containing a carbon material and a binder is prepared, and this is applied to a copper foil having a thickness of 12 μm, which is the negative electrode current collector 33, thereby forming the negative electrode 32. After the negative electrode 32 is dried and pressed, it is cut into a predetermined size with a mold to form a flat negative electrode 31. Further, the separator base paper is cut to obtain a strip-shaped separator 41.

  Then, as shown in FIG. 6, separators 41 are arranged on the front and back of the positive electrode 21, the positive electrode 21 and the separator 41 are overlapped, and then a predetermined area is flattened and wound into a flat roll shape. At this time, as shown in FIG. 7, the positive electrode 21 and the separator 41 are sequentially wound while the negative electrode 31 is sandwiched between the flat portions of the positive electrode 21 via the separator 41. By repeating this, a flat roll electrode group 11 as shown in FIGS. 3 and 4 is produced. Note that the flat roll-shaped electrode group 11 as in the present embodiment has a structure in which a pressing force can be applied in a direction perpendicular to the pair of flat surfaces (that is, the electrode group thickness direction). Unlike the conventional cylindrical roll electrode group, it is easy to achieve high output.

  Thereafter, the positive electrode external terminal 25 is ultrasonically welded to the end of the positive electrode current collector 23, and the negative electrode external terminal 35 is ultrasonically welded to the end of the negative electrode current collector 33. Next, the electrode group 11 with a terminal is accommodated in the container 51, and an opening part is closed. At this time, lithium metal is disposed above and below the electrode group 11 and stored in the container 51. Thereafter, the organic electrolyte is injected while evacuating, so that the accommodating space in the container 51 is surely filled with the organic electrolyte. Further, the container 51 is sealed and held for a predetermined time to advance lithium ion pre-doping. As a result, the lithium ion capacitor 10 shown in FIG. 1 is completed.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In the lithium ion capacitor 10 of the present embodiment, the strip-shaped positive electrode 21 and the strip-shaped separator 41 are overlapped and wound into a flat roll shape, and the separator 41 is sandwiched between the flat portions of the wound positive electrode 21. The electrode group 11 is formed by sandwiching the negative electrode 31 through the electrode. In this way, the formation process can be simplified as compared with a conventional capacitor in which the positive electrode 61 and the separator 63 are overlapped one by one to form the electrode group 65 (see FIG. 16). In addition, since a plurality of flat negative electrodes 31 are sandwiched between the electrode groups 11, bending of the negative electrode can be prevented when winding in a flat roll shape. Therefore, since each negative electrode 31 has a uniform thickness, current concentration is unlikely to occur, and precipitation of lithium metal, which is a cause of hindering high output, can be avoided. Further, the external electrodes 25 and 35 can be easily connected to the flat portion of the positive electrode 21 and the flat negative electrode 31 constituting the electrode group 11. Furthermore, since the electrode group 11 has a structure in which the positive electrodes 21 and the negative electrodes 31 are alternately stacked via the separators 41, the lithium ion capacitor 10 excellent in rapid charge / discharge can be realized.

  As described above, according to the present embodiment, it is possible to provide the lithium ion capacitor 10 having the structure suitable for achieving the high output while the electrode group 11 can be efficiently manufactured in a short time.

  (2) In the electrode group 11 of the present embodiment, since the area of the flat portion of the positive electrode 21 is larger than the area of the negative electrode 31, current concentration is avoided and lithium metal deposition can be reliably prevented.

(3) In the electrode group 11 of the present embodiment, the negative electrode current collector 33 constituting the negative electrode 31 is formed of a porous material, whereby the negative electrode 32 can be efficiently pre-doped with lithium ions. .
[Second Embodiment]

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the method of forming the electrode group 11A is different from that of the first embodiment, and other than that is the same as the lithium ion capacitor 10 of the first embodiment.

  Specifically, as shown in FIG. 8, the electrode group 11 </ b> A of the present embodiment is folded in a bellows shape (in other words, a zigzag shape) by overlapping the belt-like positive electrode 21 and the belt-like separator 41. The negative electrode 31 is sandwiched between the flat portions of the positive electrode 21 in a state via a separator 41.

  Also in the case of forming the electrode group 11A of the present embodiment, as in the first embodiment, the strip-like positive electrode 21, the strip-like separator 41, and the flat and plural negative electrodes 31 without bending are used ( (See FIG. 5). Then, as shown in FIG. 9, separators 41 are arranged on the front and back sides of the positive electrode 21, the positive electrode 21 and the separator 41 are overlapped, and then a predetermined area is flattened and folded into a bellows shape. At this time, the positive electrode 21 and the separator 41 are folded while the negative electrode 31 is sandwiched between the flat portions of the positive electrode 21 via the separator 41. By repeating this, an electrode group 11A as shown in FIG. 8 is produced.

  Even when the electrode group 11A is formed as in the present embodiment, it is not necessary to superimpose the positive electrodes 61 and the separators 63 one by one as in the prior art, so that the formation process can be simplified. Further, since a plurality of flat negative electrodes 31 are sandwiched in the electrode group 11A, it is possible to prevent the negative electrodes from being bent when folded in a bellows shape. Therefore, since each negative electrode 31 has a uniform thickness, current concentration, which is one cause of hindering high output, hardly occurs, and precipitation of lithium metal can be avoided.

  In addition, you may change each embodiment of this invention as follows.

  In each of the embodiments described above, the belt-like positive electrode 21 is formed by applying the positive electrode 22 in a planar shape on the positive electrode current collector 23, but is not limited thereto. Since the part which does not oppose the negative electrode 31 in the positive electrode 21 is unnecessary, for example, as shown in FIG. 10, while leaving the positive electrode 22 in a position facing the negative electrode 31, the positive electrode 22 in another part is previously connected to the positive electrode. The positive electrode 21a removed from the current collector 23 may be used. In this case, the island-like positive electrode 22 left on the positive electrode current collector 23 is a portion corresponding to the normal portion of the positive electrode 21 and has a larger area than the negative electrode 31. And the separator 41 is arrange | positioned on the front and back of the positive electrode 21a, and these positive electrodes 21a and the separator 41 are piled up. Thereafter, the positive electrode 21a and the separator 41 are wound in a flat roll shape or folded in a bellows shape, and the negative electrode 31 is sandwiched between the flat portions of the positive electrode 21a in a wound or folded state through the separator 41, 11A is produced. Even if comprised in this way, it is not necessary to pile up the positive electrode 21a one by one. Further, in the positive electrode 21a, the portion where the positive electrode 22 is removed can be easily bent as compared with the portion where the positive electrode 22 is left. For this reason, the electrode groups 11 and 11A can be produced in a short time.

  In each of the above-described embodiments, the electrode groups 11 and 11A are configured by using a plurality of plate-like negative electrodes 31. However, the present invention is not limited to this. For example, as shown in FIG. The negative electrode 31a may be used to form the electrode groups 11 and 11A. In this negative electrode 31 a, the negative electrode 32 at the position opposite to the normal part of the positive electrode 21 is left, while the negative electrode 32 in other parts is previously removed from the negative electrode current collector 33. In this case, the island-shaped negative electrode 32 remaining on the negative electrode current collector 33 is formed so that the area thereof is smaller than the normal portion of the positive electrode 21. And the electrode groups 11 and 11A are produced by superimposing the strip | belt-shaped positive electrode 21, the strip | belt-shaped separator 41, and the strip | belt-shaped negative electrode 31a, winding in a flat roll shape, or folding in a bellows shape. With this configuration, it is not necessary to superimpose the negative electrodes 31a one by one. Further, in the negative electrode 31a, the portion where the negative electrode 32 is removed can be easily bent as compared with the portion where the negative electrode 32 is left. For this reason, the electrode groups 11 and 11A can be produced in a short time.

  Further, as shown in FIG. 12, the electrode groups 11 and 11A may be formed using a strip-shaped negative electrode 31b with a part cut away. The negative electrode 31b in FIG. 12 is formed in a comb-like shape by cutting out a portion that does not face the flat portion of the positive electrode 21 and that is a bent portion. Furthermore, as shown in FIG. 13, the electrode groups 11 and 11A may be formed using the positive electrode 21b cut out in a comb-like shape, similarly to the negative electrode 31b. When such a positive electrode 21b and a negative electrode 31b are used, it is not necessary to superimpose each electrode one by one, and the positive electrode 21b and the negative electrode 31b can be easily bent. Can be formed in time. Further, by using the electrode groups 11 and 11A, it is possible to reduce the weight of the lithium ion capacitor.

  -In the lithium ion capacitor 10 of the said 1st Embodiment, the side part of the electrode group 11 formed in flat roll shape is an unnecessary part which the positive electrode 21 and the negative electrode 31 do not oppose. Therefore, as shown in FIG. 14, the side surface portion (a portion excluding the layer portion) of the electrode group 11 may be cut and removed. If comprised in this way, lithium ion pre dope can be efficiently performed from the side part of the electrode group 11. FIG. Further, the weight of the lithium ion capacitor can be reduced.

  In the lithium ion capacitor 10 of each of the above embodiments, the positive electrode external terminal 25 and the negative electrode external terminal 35 are drawn out in opposite directions, but the present invention is not limited to this, and the positive electrode external terminal from the same direction 25 and the negative electrode external terminal 35 may be drawn out.

  -In the lithium ion capacitor 10 of each said embodiment, although the soft container which consists of an aluminum laminated film was used as the container 51 which accommodates the electrode groups 11 and 11A, it is not limited to this, Aluminum etc. A hard container made of a metal material may be used.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the respective embodiments described above are listed below.

  (1) In the means 1, in the electrode group, the positive electrode in the wound or folded state leaves the positive electrode in a position facing the negative electrode while the positive electrode in another part is previously placed on the negative electrode current collector. A lithium ion capacitor having a structure removed from the lithium ion capacitor.

  (2) The lithium ion capacitor according to any one of means 1 to 5, wherein the positive electrode external terminal and the negative electrode external terminal are drawn out in opposite directions.

  (3) A structure in which a container, a positive electrode made of a carbon material is formed on a positive current collector, and a negative electrode made of a material capable of occluding and releasing lithium are formed on the negative current collector And a separator interposed between the positive electrode and the negative electrode, an electrode group including the positive electrode, the negative electrode, and the separator is accommodated in the container together with an electrolyte, and the negative electrode is previously doped with lithium ions A positive electrode external terminal connected to the positive electrode current collector and a negative electrode external terminal connected to the negative electrode current collector are both drawn out from the container, A positive electrode, a strip-shaped separator, and a flat and non-bent negative electrode, and a flat roll shape by overlapping the strip-shaped positive electrode and the strip-shaped separator. The lithium ion capacitor is produced by forming the electrode group by winding or folding in a bellows shape, and sandwiching the negative electrode through the separator between the flat portions of the positive electrode in a wound or folded state. Method.

DESCRIPTION OF SYMBOLS 10 ... Lithium ion capacitor 11, 11A ... Electrode group 21, 21a ... Positive electrode 22 ... Positive electrode 23 ... Positive electrode collector 25 ... Positive electrode external terminal 31, 31a ... Negative electrode 32 ... Negative electrode 33 ... Negative electrode collector 35 ... Negative electrode External terminal 41 ... Separator 51 ... Container as container

Claims (4)

A positive electrode having a structure in which a positive electrode made of a carbon material is formed on a positive electrode current collector, and a negative electrode having a structure in which a negative electrode made of a material capable of inserting and extracting lithium is formed on the negative electrode current collector; A separator interposed between the positive electrode and the negative electrode, an electrode group comprising the positive electrode, the negative electrode and the separator is housed in the housing together with an electrolyte, and the negative electrode is pre-doped with lithium ions, In the lithium ion capacitor in which both the external terminal for positive electrode connected to the positive electrode current collector and the external terminal for negative electrode connected to the negative electrode current collector are drawn from the container,
The electrode group uses a strip-shaped positive electrode, a strip-shaped separator, and a flat plate and a plurality of negative electrodes without bending, and the strip-shaped positive electrode and the strip-shaped separator are overlapped and wound into a flat roll shape or in a bellows shape. A lithium ion capacitor having a structure in which the negative electrode is sandwiched between the flat portions of the positive electrode in a folded state or a folded state, with the separator interposed therebetween. A positive electrode having a structure in which a positive electrode made of a carbon material is formed on a positive electrode current collector, and a negative electrode having a structure in which a negative electrode made of a material capable of inserting and extracting lithium is formed on the negative electrode current collector; A separator interposed between the positive electrode and the negative electrode, an electrode group comprising the positive electrode, the negative electrode and the separator is housed in the housing together with an electrolyte, and the negative electrode is pre-doped with lithium ions, In the lithium ion capacitor in which the positive electrode external terminal connected to the positive electrode current collector and the negative electrode external terminal connected to the negative electrode current collector are drawn from the container,
The electrode group is a negative electrode positioned between the flat portions of the positive electrode in a wound or folded state while the electrode group is wound in a flat roll shape or folded in a bellows shape by overlapping a belt-like positive electrode, a belt-like separator and a belt-like negative electrode While leaving the electrode, remove the positive and negative electrodes other than the flat part from the current collector in advance, make the electrode area of the positive electrode smaller than the electrode area of the negative electrode, and the outer periphery of the positive electrode is inside the outer periphery of the negative electrode A lithium ion capacitor comprising:   3. The lithium ion capacitor according to claim 1, wherein at least the negative electrode current collector of the positive electrode current collector and the negative electrode current collector is a porous body.   4. The lithium ion capacitor according to claim 1, wherein the positive electrode and the separator are partially cut at a portion of the electrode group excluding a layered portion. 5.

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