JP2012124412A - Storage cell and storage module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate flowing of an electric current in a storage cell even when a mounting position is distant from an electrode terminal.SOLUTION: In a storage cell comprised of laminated collecting electrodes (1), active material layers (2) and a separator (3), as electrode terminals (1a, 1b) of the collecting electrode (1) are farther from their end sections (1c), the thickness of the collecting electrode (1) becomes larger and the thickness of the active material layer (2) becomes smaller.

Description

  The present invention relates to a power storage cell and a power storage module including the power storage cell.

  In the conventional lead-acid battery for automobiles described in Patent Document 1, the thickness of the upper active material in the vicinity of the electrode terminal (current collection tab) is reduced, and the thickness of the lower active material away from the electrode terminal (current collection tab) is increased. Thus, the electrode plate thickness in the vertical direction of the battery is changed. Thereby, the non-uniformity of the charge / discharge reaction is eliminated at the top and bottom of the battery. In the battery of the prior art described in Patent Document 2, the thickness of the collector electrode (current collector) is maximized in the electrode terminal (lead) portion where current is concentrated, and the collector electrode thickness is reduced as the distance from the lead increases. Yes. As a result, resistance and heat generated in the collector electrode are reduced.

JP 2003-187790 A JP-A-9-199177

  However, in the prior arts of Patent Documents 1 and 2, as the distance from the electrode terminal increases, it becomes difficult for the current to flow through the collector electrode and thus the inside of the storage cell, and the active material located far from the electrode terminal may not be effectively used. .

  The present invention has been made paying attention to such a conventional problem, and an object of the present invention is to make it easy for a current to flow inside the storage cell even if it is separated from the electrode terminal.

  A power storage cell according to an aspect of the present invention includes a stacked collector electrode, an active material layer, and a separator. The thickness of the collector electrode increases and the thickness of the active material layer decreases as the distance from the end where the electrode terminal of the collector electrode is provided.

  According to the present invention, an electric current easily flows in the storage cell even if it is separated from the electrode terminal, and an active material located at a position far from the electrode terminal can be effectively used.

It is a perspective view which shows the laminated structure of the electrical storage cell which concerns on 1st embodiment. (A) It is a perspective view which shows the laminated body which concerns on 1st embodiment. (B) It is a perspective view which shows the case which accommodates the laminated body which concerns on 1st embodiment. It is the side view which looked at the single cell (unit cell) which concerns on 1st embodiment in the horizontal direction. It is a circuit diagram which shows the equivalent circuit of the single cell which concerns on 1st embodiment. (A) It is a side view which shows an electrode body in case a collector electrode has uniform thickness. (B) It is a side view which shows the electrode body which concerns on 1st embodiment. It is a side view which shows the laminated | stacked single cell which concerns on 1st embodiment. It is a perspective view which shows the laminated structure of the electrical storage cell which concerns on 2nd embodiment. (A) It is a perspective view which shows the laminated body which concerns on 2nd embodiment. (B) It is a perspective view which shows the case which accommodates the laminated body which concerns on 2nd embodiment. It is the side view which looked at the single cell (unit cell) which concerns on 2nd embodiment in the horizontal direction. It is a circuit diagram which shows the equivalent circuit of the single cell which concerns on 2nd embodiment. It is a side view which shows the laminated | stacked single cell which concerns on 2nd embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in more detail with reference to the drawings.

[First embodiment]
FIG. 1 is a diagram illustrating a stacked structure of the storage cell according to the present embodiment. In FIG. 1, the X axis indicates the horizontal direction, the Y axis indicates the stacking direction (thickness direction), and the Z axis indicates the vertical direction. The X axis, the Y axis, and the Z axis are perpendicular to each other. In the present embodiment, the storage cell is an electric double layer capacitor (hereinafter also simply referred to as “capacitor”). A power storage module can be configured by connecting a plurality of power storage cells in series or in parallel.

  Referring to FIG. 1, in a power storage cell 10, a collector electrode (collector foil) 1, an active material layer 2, and a separator 3 are laminated. At the vertical end 1c of the collector electrode 1, the upper electrode terminal (positive electrode terminal) 1a in the vertical direction or the lower electrode terminal (negative electrode terminal) 1b in the vertical direction are alternately arranged. The collector electrode 1 is a positive electrode having a positive electrode terminal 1a or a negative electrode having a negative electrode terminal 1b. One of the opposing collector electrodes 1 is a positive electrode and the other is a negative electrode. The plurality of positive terminals 1a and the plurality of negative terminals 1b are respectively bundled and electrically connected.

  As shown in FIGS. 2A and 2B, the stacked body 4 is sealed with a container 5 to complete a storage cell (capacitor). The laminated body 4 is dried in order to remove moisture, and then housed in the container 5 in a dry atmosphere such as nitrogen gas by using a glove box or the like. As the container 5, for example, an aluminum laminate film container is used. Further, in this dry atmosphere, impregnation with an electrolytic solution and subsequent electrolytic purification are performed. Thereafter, the inside of the container 5 is sealed after removing gas used as a dry atmosphere and excess electrolyte solution by evacuation. When an aluminum laminate film is used as the container 5, heat sealing is used as a sealing method. As the electrolytic solution, a non-aqueous electrolytic solution is used.

  An aluminum foil can be used as the collector electrode 1. As an active material constituting the active material layer 2, a carbon material having a large surface area such as activated carbon can be used. As the separator 3, a cellulose-based porous material can be used.

  The active material of the active material layer 2 is attached to the surface of the collector electrode 1. For example, the active material layer 2 is obtained by applying a mixture obtained by adding an adhesive and a conductive agent to a powdered carbon material and kneading them into a paste, and then drying the mixture on the surface of the collector electrode 1. Hereinafter, the active material layer 2 attached on the surface of the current collector 1 and the collector electrode 1 and the active material layer 2 are integrated will be referred to as electrode bodies (1, 2).

  FIG. 3 is a side view of a single cell of the storage cell as viewed in the horizontal direction. In one electrode body, the thickness of the collecting electrode 1 increases along the vertical direction as the distance from the end 1c where the electrode terminals 1a and 1b are provided. For example, the thickness of the collector electrode 1 increases in proportion to the distance from the end 1c. However, the thickness of the collector electrode 1 is somewhat thick even in the vicinity of the end 1c in order to suppress heat generation.

  On the other hand, the thickness of the active material layer 2 decreases as the distance from the end 1c provided with the electrode terminals 1a and 1b increases along the vertical direction. For example, the thickness of the active material layer 2 decreases in proportion to the distance from the end 1c.

  Since the thickness of the whole electrode body (1, 2) is substantially uniform along the vertical direction and the horizontal direction, the electrode body (1, 2) and the flat separator 3 are easily laminated. In addition, the collector electrode 1 in which thickness changes is produced by rolling the collector electrode 1 and adjusting the pressure applied at the time of rolling, for example.

  FIG. 4 is a circuit diagram showing an equivalent circuit of a single cell. The cross-section in the stacking direction of the collecting electrode 1 increases as the thickness of the collecting electrode 1 increases and the distance from the end 1c where the electrode terminals 1a and 1b are arranged increases. For this reason, the electrical resistance of the collector electrode 1 decreases as the distance from the end 1c increases (r1 (= R)> r2> r3>...> Rn). Therefore, current easily flows at positions away from the electrode terminals 1a and 1b in the vertical direction in the collector electrode 1 or the storage cell. In addition, when the collector electrode 1 has a uniform thickness d (when r1 = r2 = r3 =... = Rn (= constant value R)) (FIG. 5A), the internal resistance of the entire storage cell Decrease.

  Further, as the thickness of the active material layer 2 decreases, the electrical resistance in the stacking direction (thickness direction) of the active material layer 2 decreases as the distance from the end 1c increases. For this reason, the current easily flows even at a position away from the electrode terminals 1a and 1b in the storage cell. Further, as the thickness of the active material layer 2 decreases, the electrical resistance of the storage cell decreases as a whole.

  Unlike the second embodiment described later, one electrode terminal (positive electrode terminal) 1a is arranged on the upper side in the vertical direction, and the other electrode terminal (negative electrode terminal) 1b is arranged on the lower side in the vertical direction. The total thickness of the two left and right active material layers 2 in a single cell does not change in the vertical direction. Therefore, the capacitances C0, C1, C2, C3,..., Cn are almost equal, and the charge / discharge sharing is easily equalized in the vertical direction.

Furthermore, in the present embodiment, as shown in FIG. 5B, the contact area between the collector electrode 1 and the active material layer 2 is increased as compared with the case where the collector electrode 1 has a uniform thickness (FIG. 5A). . This is because the length of the applied active material layer 2 increases from L to L ′ (L ′ = (L ² + a ² ) ^1/2 ). In FIG. 5A, when the lateral width W of the applied active material layer 2 is assumed, the contact area S between the collector electrode 1 and the active material layer 2 is W × L (S = W × L). However, in FIG. 5B, the contact area S ′ between the collector electrode 1 and the active material layer 2 is W × L ′ (S = W × L ′).

  A plurality of unit cells made of the electrode bodies (1, 2) and separators 3 obtained as shown in FIG. A conductive adhesive or the like may be applied between the collector electrodes 1 that are in contact with each other. In addition, it is also possible to produce a winding type (cylindrical type) storage cell configured by winding the strip-shaped electrode bodies (1, 2) and the separator 3 in a roll shape.

-Effect-
According to the first embodiment, the thickness of the collecting electrode 1 increases and the thickness of the active material layer 2 decreases as the distance from the end 1c where the electrode terminal 1a or 1b of the collecting electrode 1 is provided. For this reason, in the single cell, the electrical resistance is reduced at a position away from the electrode terminals 1a and 1b, and the current easily flows. Thereby, the charge / discharge speed of the storage cell is increased. Furthermore, since the active material can be effectively used even at positions away from the electrode terminals 1a and 1b, the amount of active material used can be reduced, and the cost of the storage cell is reduced.

  In the direction perpendicular to the stacking direction (longitudinal direction and lateral direction), the sum of the thickness of the collector electrode 1 and the thickness of the active material layer 2 is constant, and the total thickness of the electrode bodies (1, 2) becomes substantially uniform, It becomes easy to laminate | stack the electrode body (1, 2) and the flat separator 3.

  In the direction perpendicular to the laminating direction (longitudinal direction), the electrode terminal 1a on the positive electrode side is provided on one side, and the electrode terminal 1b on the negative electrode side is provided on the other side. Even if the thickness is changed, the change in the vertical direction of the capacitance in the single cell is suppressed.

[Second Embodiment]
Referring to FIG. 7, in the second embodiment, the collector electrode 1 is alternately provided with the right electrode terminal 1a or the left electrode terminal 1b at the upper end 1c in the vertical direction. As shown in FIGS. 8A and 8B, the stacked body 4 is sealed with the container 5 to complete the storage cell 10.

  FIG. 9 is a side view of a single battery cell as viewed in the horizontal direction, as in the first embodiment. The thickness of the collector electrode 1 increases along the vertical direction as the distance from the end 1c provided with the electrode terminals 1a and 1b increases. On the other hand, the thickness of the active material layer 2 decreases as the distance from the end 1c provided with the electrode terminals 1a and 1b increases along the vertical direction. Since the thickness of the whole electrode body (1, 2) is substantially uniform along the vertical direction, the electrode body (1, 2) and the flat separator 3 are easily laminated.

  FIG. 10 is a circuit diagram showing an equivalent circuit of a single cell. As in the first embodiment, the electrical resistance of the collector electrode 1 decreases as the distance from the end 1c where the electrode terminals 1a and 1b are provided (r1 (= R)> r2> r3>...> Rn). Therefore, current easily flows at a position away from the electrode terminals 1a and 1b in the collector electrode 1 or the storage cell. In addition, the internal resistance of the entire storage cell is reduced as compared with the case where the collector electrode 1 has a uniform thickness d.

  In addition, since the thickness of the active material layer 2 is reduced, current easily flows at positions away from the electrode terminals 1a and 1b in the storage cell. Further, as the thickness of the active material layer 2 decreases, the electrical resistance of the storage cell decreases as a whole.

  Note that the total thickness of the two left and right active material layers 2 in the single cell decreases with increasing distance from the end 1c where the electrode terminals 1a and 1b are provided in the vertical direction, and C1> C2> C3>. ..> Cn, and the charge / discharge sharing becomes uneven. However, since current easily flows even at positions away from the electrode terminals 1a and 1b, nonuniform distribution of the capacitances C1, C2, C3,..., Cn is improved.

  A plurality of unit cells made of the electrode bodies (1, 2) and the separators 3 obtained as shown in FIG. 11 are stacked to produce a storage cell. In addition, it is also possible to produce a winding type (cylindrical type) storage cell configured by winding the strip-shaped electrode bodies (1, 2) and the separator 3 in a roll shape.

-Effect-
According to the second embodiment, since the electrode terminal exists only in one direction (vertical direction), it is easy to install the storage cell upright.

  The present invention is not limited to the first embodiment and the second embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and these are also included in the technical scope of the present invention. It is clear that For example, if the storage cell is not an electric double layer capacitor but a lithium ion battery, the active material on the positive electrode side is a lithium-transition metal composite oxide (for example, LiCoO2), the active material on the negative electrode side is carbon, and the separator is ( For example, a polyamide nonwoven fabric may be used.

DESCRIPTION OF SYMBOLS 1 Collector electrode 1a, 1b Electrode terminal 1c End part 2 Active material layer 3 Separator 4 Laminated body 10 Electric storage cell

Claims (5)

A storage cell comprising a stacked collector electrode, an active material layer, and a separator,
The electrical storage cell characterized by the thickness of the said collector electrode increasing, and the thickness of the said active material layer decreasing as it leaves | separates from the edge part in which the electrode terminal of the said collector electrode is provided.   The storage cell according to claim 1, wherein the sum of the thickness of the collector electrode and the thickness of the active material layer is constant in a direction perpendicular to the stacking direction.   The electrical storage cell according to claim 1, wherein the electrical resistance of the collector electrode decreases as the distance from the end portion increases.   The storage cell according to claim 1, wherein the electrode terminal on the positive electrode side is provided on one side and the electrode terminal on the negative electrode side is provided on the other side in a direction perpendicular to the stacking direction.   A power storage module comprising a plurality of power storage cells according to claim 1 connected to each other.