JP4658682B2 - Electrochemical element - Google Patents

Description

  The present invention relates to an electrochemical element configured by laminating a plurality of electrode sheets and separators.

  Generally, negative or positive charges are alternately stored in each electrode sheet by alternately laminating electrode sheets having electrode layers formed on both sides of a rectangular sheet-shaped current collector foil via insulating separators. Electrochemical elements that can be used are known. As such an electrochemical element, conventionally, one side of the electrode sheet that stores negative charges protrudes outward from the electrode layer or separator, and the other side of the electrode sheet that stores positive charges is opposite to the one side. It is known that the structure is simplified by projecting the sides outward from the electrode layer or the separator so that the negative charge outlet and the positive charge outlet are directed in opposite directions. (See Patent Document 1). Specifically, in this structure, a conductive shim (spacer) is sandwiched between the protruding portions, and each electrode is sandwiched between conductive “tags” having a U shape. Current is collected from the sheet.

JP-A-11-274004 (paragraph 0035, FIG. 3)

  However, since “Taga” in the prior art has a U-shape, it cannot be held by applying an appropriate pressure in the stacking direction to the stacked electrode sheets. Therefore, the adhesiveness between the current collector foil and the electrode layer is deteriorated, and the electric resistance may be increased.

  Therefore, an object of the present invention is to provide an electrochemical element capable of applying an appropriate pressure in the stacking direction to the stacked electrode sheets.

The invention according to claim 1 of the present invention that solves the above-mentioned problems is arranged between a plurality of electrode sheets in which an electrode layer is formed leaving a lead portion on a current collector foil, and between the electrode layers of the plurality of electrode sheets A separator disposed between the lead portions of the plurality of electrode sheets, and an electrochemical element in which the electrode layer and the separator are impregnated with an electrolyte, And further comprising two substantially L-shaped current collecting plates each having a current collecting wall for collecting current from a lead portion and a holding wall for holding an end electrode sheet among the stacked electrode sheets. The electrical wall has a bead portion extending in the electrode sheet laminating direction and convex toward the electrode sheet side, and the lead portion and the shim have a notch portion that engages with the bead portion, The two current collector plates The electrode sheet on which the holding wall is laminated is sandwiched in the laminating direction, and the area of the holding wall is formed larger than the area of the electrode sheet, and the holding wall, the lead portion, and the shim are arranged in the laminating direction. And a fastening member that is fastened so as to pressurize between the holding walls of the two current collecting plates in the stacking direction.

  According to the first aspect of the present invention, the stacked electrode sheets are sandwiched in the stacking direction by the holding walls of the two substantially L-shaped current collecting plates. At this time, since each holding wall is formed larger than the area of the electrode sheet, the entire surface of the electrode sheet adjacent to the holding wall is uniformly pressed by the holding wall, and each electrode sheet is in a good pressure state. It will be held at. For this reason, the current collector foil and the electrode layer can be brought into close contact with each other to reduce the electric resistance, and the distance between the electrodes sandwiching the separator can be shortened to increase the capacitance.

The invention according to claim 2 is the electrochemical element according to claim 1, wherein the fastening member is made of an insulator.
According to a third aspect of the invention, an electrochemical device according to claim 1 or claim 2, the electrode sheet side surface of the retaining wall of the collector plate, an insulating treatment is applied It is characterized by that.

According to invention of Claim 2, the short circuit between the two current collection plates by a fastening member can be prevented.
According to the invention described in claim 3 , for example, even when one of the current collecting plates is a negative electrode and the electrode sheet adjacent to the holding wall of the current collecting plate is a positive electrode, the insulation applied to the holding wall By the treatment, it is possible to prevent contact between different polarities.

Invention of Claim 4 is the electrochemical element of any one of Claim 1 thru | or 3, Comprising: When pressing the said electrode sheet in a lamination direction with the said 2 current collection plate, The pressure is 0.3 (MPa) to 1.0 (MPa).

According to invention of Claim 4 , since the laminated body of an electrode sheet is hold | maintained with the applied pressure which becomes 0.3 (MPa)-1.0 (MPa), the distance between each electrode sheet is shortened uniformly. In addition, the load applied to each electrode sheet can be suppressed to the minimum necessary even if the electrolytic solution expands due to heat generated during use.

  According to the first aspect of the present invention, since the stacked electrode sheets are sandwiched by the holding walls of the current collecting plate having an area larger than the area of the electrode sheets, the stacked electrode sheets are moderate in the stacking direction. Can be applied.

According to invention of Claim 2, the short circuit between the two current collection plates by a fastening member can be prevented.
According to the invention described in claim 3 , even if the current collecting plate and the electrode sheet adjacent to the holding wall of the current collecting plate have different polarities, the insulation applied to the holding wall By the processing, interference between charges of different polarities can be prevented.

According to invention of Claim 4 , since the laminated body of an electrode sheet is hold | maintained with the applied pressure which becomes 0.3 (MPa)-1.0 (MPa), the distance between each electrode sheet is shortened uniformly. In addition, the load applied to each electrode sheet can be suppressed to the minimum necessary even if the electrolytic solution expands due to heat generated during use.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing the internal structure of an electric double layer capacitor (electrochemical element) according to this embodiment, and FIG. 2 is an exploded perspective view showing the structure of an electrode sheet assembly according to this embodiment. FIG. 3 is an exploded perspective view showing the structure of the laminate.

  As shown in FIG. 1, an electric double layer capacitor 10 (hereinafter also simply referred to as “capacitor 10”) includes a casing 1 and an electrode sheet assembly EA accommodated in the casing 1 together with an electrolytic solution. Configured.

  The casing 1 is composed of a rectangular cylindrical cylinder 11 and a lid body 12 attached to the upper and lower openings of the cylindrical body 11. And this casing 1 comes to be sealed by attaching the edge part of the cover body 12 to the edge part of the up-and-down opening part of the cylinder 11 by a bending process, a crimping process, or welding (fusion | fusion). ing.

  As shown in FIG. 2, the electrode sheet assembly EA includes a laminated body LA composed of a plurality of electrode sheets 2 mainly laminated, and two L-shaped lead plates (collectors) sandwiching the laminated body LA in the laminating direction. Electric plate) 3.

  As shown in FIG. 3, the laminate LA includes a plurality of electrode sheets 2 for storing electric charge, separators 4 provided between the electrode sheets 2, and a predetermined electrode sheet 2 or between the electrode sheets 2 and L. And a shim 5 provided between the lead plate 3 (see FIG. 1).

  The electrode sheet 2 is composed of a substantially rectangular current collecting foil 2a and electrode layers 2b formed on both surfaces of the current collecting foil 2a. The current collector foil 2a is formed of a conductive material such as an aluminum foil. The electrode layer 2b is mainly composed of activated carbon, and is formed in a substantially rectangular shape over substantially the entire surface excluding one side portion of the current collector foil 2a. One side portion of the current collector foil 2a where the electrode layer 2b is not formed serves as a lead portion 2c as an outlet for the electric charge stored in each electrode layer 2b.

  Further, a through hole 2d for electrolyte injection is formed at the center of the electrode sheet 2, and two long holes 2e contributing to weight reduction and electrolyte penetration are inserted into the lead 2c and bolts inserted. Two common circular holes 2f are formed so as to pass therethrough. Further, a notch 2g that mainly contributes to weight reduction is formed at the edge of the lead portion 2c of the electrode sheet 2 (specifically, between the four holes 2e and 2f). The plurality of electrode sheets 2 formed in this way are configured such that a positive charge storage and a negative charge storage are alternately stacked with a separator 4 interposed therebetween, and a positive charge storage. The lead portion 2c of the electrode sheet 2 for storing charges is aligned in a predetermined direction, and the lead portion 2c of the electrode sheet 2 for storing negative charges is aligned in a direction opposite to the predetermined direction (different direction). ing.

  The separator 4 is an insulating member formed in a substantially rectangular sheet shape, and insulates adjacent electrode sheets 2 having different polarities (a pair of electrode sheets 2 in which the lead portions 2c face each other in opposite directions). The separator 4 is formed to have a size that slightly protrudes from the peripheral edge of the electrode layer 2b of the electrode sheet 2 and that does not block the long hole 2e and the hole 2f, and the center thereof. A through hole 4d for electrolyte injection is formed in the part with a size smaller than the through hole 2d of the electrode sheet 2 (see FIG. 1).

  The shim 5 is a substantially strip-shaped member having electrical conductivity, and the corners thereof are appropriately chamfered into an R shape, and have notches 5g corresponding to the notches 2g of the electrode sheet 2 described above on both side edges. It is formed in a simple shape. The shim 5 is appropriately formed with two long holes 5e and two holes 5f corresponding to the long holes 2e and the holes 2f of the electrode sheet 2, respectively. The shim 5 is formed between the lead portions 2c of the adjacent electrode sheets 2 having the same polarity (a pair of electrode sheets 2 in which the lead portions 2c face each other in the same direction) or between the lead portions 2c from the end. It is arranged between the lead portion 2c and the L-shaped lead plate 3 (see FIG. 1). Here, since the distance between the electrode sheet 2 located second from the end and the L-shaped lead plate 3 is shorter than the distance between the lead portions 2c of the electrode sheet 2 having the same polarity, Two types of shims 5 (hereinafter also referred to as “first shim 5A” and “second shim 5B”) having different sizes are provided. In the laminated body LA, a space is formed by the long hole 2e of the electrode sheet 2 and the long hole 5e of the shim 5 communicating with each other. This space can be made to function as a buffer unit responsible for an increase in volume when gas is generated due to decomposition of the electrolytic solution or the like.

  As shown in FIG. 2, the L-shaped lead plate 3 is a conductive member, and a current collecting wall 31 that collects current from the electrode sheet 2 with the same polarity, and an end of the laminated electrode sheet 2. The holding wall 32 that holds the electrode sheet 2 is formed in a substantially L shape.

  The current collecting wall 31 is formed in a square plate shape having a smaller width than the electrode sheet 2, and a predetermined bead portion 31 a extending in the stacking direction of the electrode sheet 2 is convex toward the electrode sheet 2 side at the center thereof. In addition, a bent portion 31b that is bent in a substantially L shape toward the electrode sheet 2 side and the outside is formed on the side edge portion. The bead portion 31a and the bent portion 31b formed on the current collecting wall 31 serve to improve the rigidity of the planar current collecting wall 31, and each of the notch portions 2g of the electrode sheet 2 and the shim 5 described above. By engaging with 5g, each electrode sheet 2 and each shim 5 are also positioned in the surface direction (specifically, the longitudinal direction of the shim 5). And the current collecting wall 31 formed in this way has the edge part of the bent part 31b joined to each electrode sheet 2 and each shim 5 of the same polarity by welding at a welded part 31c (see FIG. 4). Thus, the current flowing from each electrode sheet 2 is collected.

  The holding wall 32 is formed in a square plate shape having a larger area than the electrode sheet 2, and a terminal connection plug (current extraction portion) for taking out the current collected by the current collecting wall 31 from the outside at the center thereof. 6 is provided, and bolt insertion holes 32f are formed at the four corners. In the present embodiment, since the bolt is inserted so as to straddle the holding wall 32 of the two L-shaped lead plates 3, the material of the bolt is made insulative or one of the metal bolts It is necessary to prevent a short circuit between the L-shaped lead plates 3 and 3 by insulating the portion in contact with the holding wall 32. In addition, a shaft may be used instead of the bolt, and the end of the shaft arranged so as to straddle the holding walls 32 and 32 is caulked from the holding walls 32 and 32.

  Further, as shown in FIG. 1, the terminal connection plug 6 is fixed to the holding wall 32 by screwing the male plug 61 and the female plug 62 with the holding wall 32 interposed therebetween. It has a structure. Therefore, in order to cope with this, the holding wall 32 has a mounting hole 32a for inserting the male screw portion 61a of the male plug 61, an end surface of the male plug 61 on the flange portion 61b side, and an electrode sheet of the holding wall 32. A step-shaped attachment portion 32b is formed to make the two end surfaces flush.

  In addition, the surface of the holding wall 32 on the side of the electrode sheet 2 (the surface on which the terminal connection plug 6 is attached) is subjected to insulation treatment with the insulating film 32c. In this embodiment, since the holding wall 32 and the electrode sheet 2 adjacent to the holding wall 32 have the same polarity, there is no need to insulate the holding wall 32 and the electrode sheet 2, and the insulating film 32c is omitted. One shim 5A may be an insulator. However, since the insulating film 32c has a function of preventing the electrode sheet 2 from being damaged by the surface shape of the holding wall 32 (small irregularities around the terminal connection plug 6) in addition to the insulating function, It is desirable to provide it as follows. The insulating film 32c is provided with a hole 32d corresponding to the electrolyte solution injection / discharge hole 61c formed in the male plug 61 of the terminal connection plug 6.

  Further, a step 32 e serving as a substitute for the shim 5 is formed at the end of the holding wall 32 on the side of the current collecting wall 31. That is, when the stepped portion 32e is not provided, the thickness of the insulating film 32c and the thickness of the electrode layer 2b is added between the holding wall 32 and the lead portion 2c of the electrode sheet 2 adjacent thereto. Although it is necessary to newly provide a conductive shim (a shim having a thickness different from that of the first shim 5A and the second shim 5B), in the present embodiment, by providing the step portion 32e, the shim is eliminated, It is possible to reduce the number of parts.

Next, a method for manufacturing the capacitor 10 according to the present embodiment will be described.
As shown in FIG. 3, first, the electrode sheets 2 and the separators 4 are alternately laminated so that the directions of the lead portions 2c of the adjacent electrode sheets 2 are alternately reversed. Moreover, when laminating | stacking in this way, the shim 5 is arrange | positioned suitably with respect to the lead part 2c of each electrode sheet 2. As shown in FIG.

  Then, as shown in FIG. 2, the laminated body LA is sandwiched in the stacking direction by the L-shaped lead plate 3 to which the terminal connection plug 6 and the insulating film 32c (see FIG. 1) are previously attached. At this time, the bead portion 31a and the bent portion 31b of the L-shaped lead plate 3 are appropriately engaged with the notches 2g and 5g of the electrode sheet 2 and the shim 5, and the surface of the current collecting wall 31 of the L-shaped lead plate 3 Thus, by aligning the electrode sheets 2 and the shims 5, the bolt insertion holes 32 f, 2 f, 5 f of the components 3, 2, 5 are aligned coaxially. Thereafter, bolts (not shown) are inserted into the holes 32f, 2f, and 5f, and the tips of the inserted bolts are screwed into nuts (not shown), so that the L-shaped lead plate 3 is formed as shown in FIG. The laminated body LA is held by the holding wall 32. Here, since the holding wall 32 is formed larger than the area of the electrode sheet 2 as described above, the entire surface of each electrode sheet 2 is uniformly pressed by the large holding wall 32.

  Here, the pressure applied to the laminate LA is desirably 0.3 (MPa) to 1.0 (MPa). The applied pressure is such that the thickness of the electrode sheet 2 is 0.195 to 0.310 mm, the thickness of the separator 4 is 0.02 to 0.05 mm, the material of the current collector foil 2a of the electrode sheet 2 is aluminum, the electrode When the material of the layer 2b is activated carbon and the material of the electrolytic solution is EMI, the capacitor 10 manufactured with the applied pressure is charged and then left for 13 days, so that the voltage maintenance ratio becomes 93 ± 1%. The pressure applied when. According to this, the distance between the electrode sheets 2 can be made short and uniform by holding the laminate LA with a pressing force of 0.3 (MPa) to 1.0 (MPa). Even if the electrolyte or the like expands due to heat generated when the capacitor 10 is used, the load applied to each electrode sheet 2 can be suppressed to the minimum necessary, and the voltage maintenance ratio can be kept good. Further, the pressure applied to the laminate LA in this manner is determined in advance based on the voltage maintenance rate after being left for a predetermined period after charging (or after being used a predetermined number of times), so that each bolt can be used in an inspection at the time of manufacture. The defective product can be removed in advance by measuring the torque and calculating the pressure from this torque.

  As described above, after the laminated body LA is held with an appropriate pressure, the side edge portion (bent portion 31b) of the current collecting wall 31 of the L-shaped lead plate 3, the lead portion 2c of each electrode sheet 2, and each shim 5 is completed, the manufacture of the electrode sheet assembly EA is completed. Thereafter, as shown in FIG. 1, the electrode sheet assembly EA is accommodated in the casing 1, and then an electrolytic solution is injected from the hole 61 c of the terminal connection plug 6, whereby the electrode layer 2 b of each electrode sheet 2. Each separator 4 is impregnated with an electrolytic solution. Finally, the hole 61c of the terminal connection plug 6 is sealed with a plug (not shown), whereby the manufacture of the capacitor 10 is completed.

According to the above, the following effects can be obtained in the present embodiment.
Since the laminated electrode sheet 2 is sandwiched by the holding wall 32 of the L-shaped lead plate 3 having an area larger than the area of the electrode sheet 2, an appropriate pressure is uniformly applied to the laminated electrode sheet 2 in the lamination direction. Can be granted. Then, by applying an appropriate pressing force uniformly to the electrode sheet 2 as described above, the current collector foil 2a and the electrode layer 2b can be brought into close contact with each other to reduce the electric resistance, and the inclination of each electrode sheet 2 can be reduced. Is prevented, and the distance between the electrodes at each position in the surface direction of each pair of electrode sheets 2 can be made constant and short.

  When the separator 4 is formed larger than the electrode layer 2b of the electrode sheet 2 and the through hole 4d of the separator 4 is formed smaller than the through hole 2d of the electrode sheet 2, the electrode sheet 2 and the separator 4 are stacked. In this case, each electrode sheet 2 can be reliably insulated by the separator 4 even if the electrode sheet 2 and the separator 4 are slightly deviated from the normal position.

In addition, this invention is implemented in various forms, without being limited to the said embodiment.
In the present embodiment, the first shim 5A and the second shim 5B are formed of the same material from the viewpoint of manufacturing cost. However, the present invention is not limited to this, and the first shim 5A is formed of an insulating material. May be. According to this, as shown in FIG. 1, the current flowing from the electrode sheet 2 adjacent to the first shim 5A does not go to the first shim 5A side, but only on the opposite side (the side from which current is extracted). As a result, the current can be collected more favorably. In contrast to this embodiment, when the L-shaped lead plate and the electrode sheet adjacent to the L-shaped lead plate have different polarities, insulation is provided between the lead portion of the electrode sheet having the different polarities and the L-shaped lead plate. By providing sex shims, the same effects as described above can be obtained.

  In the present embodiment, the electric double layer capacitor 10 is employed as the electrochemical element, but the present invention is not limited to this, and a battery such as a lithium ion secondary battery may be employed.

It is sectional drawing which shows the internal structure of the electric double layer capacitor which concerns on this embodiment. It is a disassembled perspective view which shows the structure of the electrode sheet assembly which concerns on this embodiment. It is a disassembled perspective view which shows the structure of a laminated body. It is a perspective view which shows the state after the assembly of an electrode sheet assembly.

Explanation of symbols

1 casing 2 electrode sheet 2a current collector foil 2b electrode layer (electrode)
2c Lead 3 L-shaped lead plate (current collector plate)
31 Current collecting wall 32 Holding wall 32c Insulating film 4 Separator 5 Shim 6 Terminal connection plug (current extraction part)
10 Electric double layer capacitor (electrochemical element)
EA electrode sheet assembly LA laminate

Claims (4)

A plurality of electrode sheets in which an electrode layer is formed leaving a lead portion on the current collector foil;
A separator disposed between electrode layers of the plurality of electrode sheets;
A shim disposed between the lead portions of the plurality of electrode sheets,
An electrochemical element in which the electrode layer and the separator are impregnated with an electrolyte,
A current collecting wall for collecting current from the lead portions of the plurality of electrode sheets;
A holding wall for holding the electrode sheet at the end of the laminated electrode sheets;
Further comprising two substantially L-shaped current collecting plates having
The current collecting wall has a bead portion that extends in the stacking direction of the electrode sheets and is convex toward the electrode sheet side,
The lead portion and the shim have a cutout portion that engages with the bead portion,
The two current collecting plates are
While sandwiching the electrode sheet laminated the holding wall in the stacking direction, the area of the holding wall is formed larger than the area of the electrode sheet,
The holding wall, the lead portion and the shim are
There is a hole communicating with each other in the stacking direction, and a fastening member is inserted into the hole to fasten the holding walls of the two current collecting plates so as to pressurize in the stacking direction. Chemical element. The electrochemical device according to claim 1, wherein the fastening member is made of an insulator. The electrochemical element according to claim 1, wherein an insulating treatment is applied to a surface of the holding wall of the current collecting plate on the electrode sheet side. The pressurizing force is 0.3 (MPa) to 1.0 (MPa) when the electrode sheet is pressed in the stacking direction by the two current collecting plates. The electrochemical element of any one of these.

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