Angular secondary battery

Abstract

This rectangular secondary battery comprises: an electrode body that includes a positive electrode plate and a negative electrode plate; a rectangular battery case that has an opening and in which the electrode body is housed; a sealing plate that seals the opening; a charge collector that is connected to an end side of the positive electrode plate or the negative electrode plate at an end section, in the length direction, of the sealing plate; and an external terminal that is provided on the outer side of the sealing plate and that is connected to the charge collector. The electrode body and the charge collector are enveloped in an insulating holder and are housed in the battery case, and the charge collector is in contact with a bottom section of the battery case with the insulating holder therebetween.

Description

Technical Field

[0001] The present invention relates to a rectangular secondary battery.

Background Art

[0002] With the increase in the output of in-vehicle secondary batteries, the current flowing through the batteries has been increasing. As a result, the amount of heat generated inside the batteries increases, and the temperature of the entire battery rises. If the temperature of the entire battery rises excessively, there is a risk of deterioration of resin parts such as gaskets and alteration of the electrolytic solution.

[0003] Patent Document 1 discloses a structure in which a current collector connected to a power generation element (electrode body) has a plurality of branched shapes in order to suppress heat generation of the current collector in a secondary battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The current collector having the structure disclosed in Patent Document 1 can reduce the amount of heat generation due to current concentration by dispersing the current. However, even if the current is dispersed, the amount of heat generated itself is dispersed inside the battery, so that the temperature rise inside the battery cannot be suppressed. In particular, in a battery through which a large current flows, the temperature inside the battery may rise excessively.

[0006] The present invention has been made in view of such a point, and its main object is to provide a secondary battery capable of suppressing the temperature rise inside the battery even when the amount of heat generation inside the battery increases.

[0007] The rectangular secondary battery according to the present invention includes an electrode body having a positive electrode plate and a negative electrode plate, a rectangular battery case having an opening and accommodating the electrode body, a sealing plate sealing the opening, a current collector connected to an end side of the positive electrode plate or the negative electrode plate at a longitudinal end of the sealing plate, and an external terminal provided outside the sealing plate and connected to the current collector. The electrode body and the current collector are wrapped by an insulating holder and accommodated in the battery case, and the current collector is in contact with the bottom of the battery case via the insulating holder.

[0008] According to the present invention, it is possible to provide a secondary battery capable of suppressing an increase in the temperature inside the battery even when the amount of heat generated inside the battery increases.

Brief Description of the Drawings

[0009]

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[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments, and can be appropriately modified without departing from the scope in which the effects of the present invention are achieved.

[0011] FIGS. 1(a) and (b) are diagrams schematically showing the configuration of a rectangular secondary battery according to an embodiment of the present invention. FIG. 1(a) is a top view, and FIG. 1(b) is a cross-sectional view taken along line Ib-Ib of FIG. 1(a).

[0012] As shown in FIGS. 1(a) and (b), in the rectangular secondary battery 1 according to the present embodiment, the electrode body 10 as a power generation element is housed together with the electrolytic solution in a rectangular battery case 11. The electrode body 10 has a structure in which a positive electrode plate and a negative electrode plate are laminated via a separator (both not shown). The positive electrode plate is provided with a positive electrode active material layer on the surface of the positive electrode core, and the negative electrode plate is provided with a negative electrode active material layer on the surface of the negative electrode core. The opening of the battery case 11 is sealed with a sealing plate 12.

[0013] The positive electrode plate and the negative electrode plate each have exposed portions 10a and 10b where no active material layer is formed at the longitudinal ends of the sealing plate 12. The exposed portions 10a and 10b extend in opposite directions in the longitudinal direction of the sealing plate 12 and are connected to the positive and negative current collectors 20A and 20B. Specifically, a plurality of exposed portions 10a and 10b are joined to the current collectors 20A and 20B in a bundled state. The joining can be performed, for example, by ultrasonic joining or the like.

[0014] The materials of the current collectors 20A and 10B are not particularly limited, but it is preferable that the exposed portion 10a of the positive electrode plate and the exposed portion 10b of the negative electrode plate are each made of the same material. Thereby, ultrasonic welding between the exposed portions 10a and 10b and the current collectors 20A and 20B can be easily performed. For example, in the case of a lithium-ion secondary battery, the current collector 20A connected to the exposed portion 10a of the positive electrode plate is preferably made of aluminum or an aluminum alloy, and the current collector 20B connected to the exposed portion 10b of the negative electrode plate is preferably made of copper or a copper alloy.

[0015] The current collectors 20A and 20B of the positive electrode are respectively connected to the positive and negative external terminals 21A and 21B provided outside the sealing plate 12 via the connecting portions 22A and 22B. Here, the connecting portions 22A and 22B penetrate through the through holes provided in the sealing plate 12 and are connected to the external terminals 21A and 21B. The connecting portions 22A and 22B are insulated from the sealing plate 12 by insulating members 30A and 30B, respectively. Also, the external terminals 21A and 21B are insulated from the sealing plate 12 by insulating members 31A and 31B, respectively.

[0016] The electrode body 10 and the current collectors 20A and 20B are wrapped by an insulating holder 40 and housed in the battery case 11. The insulating holder 40 is in a bag shape with the sealing plate 12 side open. The material of the insulating holder 40 is not particularly limited, but for example, it is made of a resin sheet such as polypropylene (PP) or polyethylene (PET).

[0017] The current collectors 20A and 20B are each in contact with the bottom 11a of the battery case 11 via the insulating holder 40. Preferably, the current collectors 20A and 20B press the insulating holder 40 and are in contact with the bottom 11a of the battery case 11. That is, it is preferable that the insulating holder 40 is compressed in the thickness direction at the portion sandwiched between the current collectors 20A and 20B and the bottom 11a of the battery case 11.

[0018] Figure 2 is an enlarged partial cross-sectional view of the vicinity of the bottom 11a of the battery case 11 of the current collector 20A in Figure 1(b).

[0019] As shown in Fig. 2, the heat generated by the current collected by the current collector 20A is dissipated to the bottom 11a of the battery case 11 via the insulating holder 40 as indicated by the arrow. Since the battery case 11 is made of a metal with high thermal conductivity, the heat transferred to the bottom 11a of the battery case 11 is quickly transferred to the entire battery case 11 and dissipated to the outside of the battery 1. Thereby, the heat generated inside the battery 1 can be quickly dissipated to the outside of the battery 1.

[0020] In the present embodiment, it is preferable that the current collector 20A is composed of a block body having a thickness in the width direction of the sealing plate 12. Thereby, since the thermal conductivity of the current collector 20A is improved, the heat generated inside the battery 1 can be dissipated to the outside of the battery 1 more quickly.

[0021] The in-vehicle rectangular secondary battery is operated by assembling modules and packs, and the pack has a cooling mechanism such as air cooling or water cooling to avoid thermal runaway. The heat dissipation to the outside in the present embodiment is efficiently exhausted by this mechanism. Therefore, as an effect of the present embodiment, simplification of the cooling mechanism can be expected by improving the cooling efficiency.

[0022] Also, the thickness of the insulating holder 40 is preferably in the range of, for example, 0.05 to 0.5 mm. If the thickness of the insulating holder 40 is less than 0.05 mm, the insulating holder 40 may be damaged when the current collector 20A presses the insulating holder 40. As a result, the insulation between the current collector 20A and the battery case 11 may deteriorate. On the other hand, if the thickness of the insulating holder 40 is greater than 0.5 mm, the heat transfer property from the current collector 20A to the bottom 11a of the battery case 11 may be reduced.

[0023] Next, with reference to Figs. 3 to 6, the assembly procedure of the battery 1 in the present embodiment will be described.

[0024] First, as shown in FIGS. 3(a) and 3(b), an electrode body 10 and current collectors 20A (20B) are prepared. As shown in FIG. 3(a), the electrode body 10 has positive and negative exposed portions 10a and 10b at both longitudinal ends of the sealing plate 12, respectively. The current collector 20A is composed of a block body as shown in FIG. 3(b), and has a hole 23 into which a connecting portion 22A (22B) is inserted at an end on the side of the sealing plate 12.

[0025] Next, as shown in FIG. 4, two electrode bodies 10A and 10B having the same structure are arranged side by side in the width direction of the sealing plate 12, and the current collector 20A is sandwiched between the exposed portions 10a and 10a of each of the electrode bodies 10A and 10B, and the exposed portions 10a, 10a and the current collector 20A are joined at the joining region 24 by, for example, ultrasonic welding or the like.

[0026] Next, as shown in FIGS. 5(a) and 5(b), the current collector 20A is fixed to the sealing plate 12 and the external terminal 21A. Here, FIG. 5(a) is an enlarged partial perspective view of the vicinity of the sealing plate 12 of the current collector 20A. FIG. 5(b) is a partial cross-sectional view taken along line Vb-Vb of FIG. 5(a).

[0027] As shown in FIGS. 5(a) and 5(b), an insulating member 30A, a sealing plate 12, an insulating member 31A, and an external terminal 21A are arranged in this order on the current collector 20A. Note that through holes are provided in the insulating member 30A, the sealing plate 12, the insulating member 31A, and the external terminal 21A in accordance with the position of the hole 23 of the current collector 20A, respectively. Further, the insulating member 30A has an outer peripheral portion that abuts against the inner peripheral surface of the through hole provided in the sealing plate 12. Then, the bolt-shaped connecting portion 22A is passed through the through holes provided in the insulating member 30A, the sealing plate 12, the insulating member 31A, and the external terminal 21A, and fastened to the screw hole 23 of the current collector 20A. Note that instead of fastening with bolts, the end portion of the connecting portion 20A may be caulked to the external terminal 21A to fix the current collector 20A and the external terminal 21A to the sealing plate 12.

[0028] Next, as shown in FIG. 6, the sealing plate 12 to which the current collector 20A and the like are integrally fixed is inserted into the insulating holder 40. Then, the electrode body 10 and the current collector 20A wrapped by the insulating holder 40 are housed in the battery case 11. Here, by setting the length of the current collector 20A in the direction perpendicular to the sealing plate 12 to a predetermined length in accordance with the height of the battery case 11, the current collector 20A can be brought into contact with the bottom 11a of the battery case 11 via the insulating holder 40. Further, by considering the thickness of the insulating holder 40 and the dimensional tolerance of the current collector 20A in the length direction, the current collector 20A can be brought into contact with the bottom 11a of the battery case 11 with the insulating holder 40 compressed in the thickness direction.

[0029] Thereafter, the opening side end of the battery case 11 and the outer peripheral portion of the sealing plate 12 are laser welded, for example, to seal the battery case 11. Finally, after injecting the electrolytic solution into the battery case 11 through the liquid injection hole 12a provided in the sealing plate 12, the liquid injection hole 12a is sealed with a plug 50 (see FIG. 1).

[0030] FIG. 7 is a partial cross-sectional view in a plane parallel to the sealing plate 12, which magnifies the vicinity of the junction between the exposed portion 10a and the current collector 20A in FIG. 4.

[0031] As described above, the current collector 20A is sandwiched between the exposed portions 10a, 10a of the two electrode bodies 10A, 10B, and the exposed portion 10a and the current collector 20A are joined. That is, the current collector 20A is composed of a block body having a thickness W in the width direction of the sealing plate 12. Thereby, since the thermal conductivity of the current collector 20A is improved, the heat generated inside the battery 1 can be transmitted to the bottom 11a of the battery case 11 more quickly.

[0032] Here, when the length of the surface where the current collector 20A contacts the exposed portions 10a, 10a is L, it is preferable that W:L is in the range of 4:1 to 1:1. Also, the current collector 20A preferably has a solid structure, but may partially have a hollow structure.

[0033] Further, the current collector 20A does not necessarily have to be substantially rectangular parallelepiped. For example, as shown in FIG. 8, one side surface of the current collector 20A may have a protruding portion A facing the electrode bodies 10A and 10B. Thereby, since the cross-sectional area in the plane parallel to the sealing plate 12 of the current collector 20A increases, the thermal conductivity of the current collector 20A can be further improved.

[0034] According to the present embodiment, in the rectangular secondary battery in which the electrode bodies 10 and the current collector 20 are wrapped by the insulating holder 40 and housed in the battery case 11, by bringing the current collector 20 into contact with the bottom portion 11a of the battery case 11 via the insulating holder 40, the heat generated in the battery 1 can be quickly transferred to the bottom portion 11a of the battery case 11 via the current collector 20 and the insulating holder 40. Thereby, the heat generated in the battery can be quickly radiated to the outside of the battery. As a result, even if the amount of heat generation occurring in the battery increases, the temperature rise inside the battery can be suppressed.

[0035] As described above, the present invention has been described with reference to the preferred embodiments, but such descriptions are not limiting matters, and of course, various modifications are possible.

[0036] Also, in the above embodiment, as the electrode body, a structure in which a positive electrode plate and a negative electrode plate are laminated via a separator is used, but a structure in which the positive electrode plate and the negative electrode plate are wound via a separator may also be used.

[0037] FIG. 9 is a partial perspective view schematically showing the structure of the current collector 20A with respect to the electrode body 10A having such a structure.

[0038] As shown in FIG. 9, the electrode bodies 10A and 10B have a plurality of exposed portions 10a at the longitudinal end portions of the sealing plate 12 of the wound electrode plates. And the plurality of exposed portions 10a are compressed in a bundled state in the central region P in the height direction of the battery case 11.

[0039] On the one hand, the current collector 20A is arranged in a state of being sandwiched between the exposed portions 10a and 10a of the electrode bodies 10A and 10B. At this time, in the central region Q in the height direction of the battery case 11, the width in the width direction of the sealing plate 12 expands toward the exposed portions 10a and 10a and contacts the exposed portions 10a and 10a. Thereby, in the regions P and Q, the current collector 20A and the exposed portions 10a and 10a can be joined by, for example, ultrasonic welding or the like.

[0040] The current collector 20A shown in FIG. 9 has a solid structure, but as shown in FIG. 10, the current collector 20A may have a hollow structure. In this case, for the hole 23 into which the connecting portion 22A (22B) is inserted, a cylindrical portion 23a may be provided at the end portion of the current collector 20A on the sealing plate 12 side, and the hole 23 may be formed in the cylindrical portion 23a. Also, as another method, caulking processing described above may be used.

[0041] Also, in the above embodiment, two electrode bodies 10A and 10B having the same structure are arranged in the battery case 11, but one electrode body may be arranged. In this case, as shown in FIG. 10, the electrode body 10 has a plurality of exposed portions 10a at the longitudinal end portions of the sealing plate 12, and these exposed portions 10a are bundled toward the width direction end portion side of the sealing plate 12. Then, in a state where the current collector 20 is brought into contact with the exposed portion 10a, the exposed portion 10a and the current collector 20 may be joined by, for example, ultrasonic welding or the like.

[0042] Also, in the above embodiment, the current collectors 20A and 20B are connected to the exposed portions 10a and 10b respectively provided at both end sides of the positive electrode plate and the negative electrode plate, but the current collector 20 may be connected to only one of the exposed portions 10a and 10b of the positive electrode plate and the negative electrode plate.

[0043] Also, in the above embodiment, an example in which the joining of the exposed portions 10a and 10b and the current collectors 20A and 20B is performed by ultrasonic welding has been described, but the present invention is not limited thereto, and for example, resistance welding or laser welding may be used.

[0044] In the above-described embodiment, the structure in which the current collectors 20A and 20B are connected to the external terminals 21A and 21B via the connecting portions 22A and 22B has been described. However, the present invention is not limited to this, and any structure may be used as long as it electrically connects the current collectors 20A and 20B and the external terminals 21A and 21B.

[0045] The rectangular secondary battery in the present embodiment is not particularly limited in terms of its type, and for example, it can be applied to a lithium ion secondary battery, a nickel hydrogen secondary battery, or the like.

Explanation of Signs

[0046] 1 Rectangular secondary battery 10(10A, 10B) Electrode body 10a, 10b Exposed portion 11 Battery case 11a Bottom 11b Flow path 12 Sealing plate 12a Liquid injection hole 20(20A, 20B) Current collector 21A, 21B External terminal 22A, 22B Connecting portion 23 Hole 23a Cylindrical portion 24 Bonding region 30A, 30B Insulating member 31A, 31B Insulating member 40 Insulating holder 50 Plug

Claims

1. An electrode body including a positive electrode plate and a negative electrode plate, A rectangular battery case having an opening and housing the electrode body, A sealing plate that seals the opening, A current collector connected to an edge of the positive electrode plate or the negative electrode plate at a longitudinal end of the sealing plate, An external terminal provided outside the sealing plate and connected to the current collector, A rectangular secondary battery comprising: The electrode body and the current collector are integrally fixed to the sealing plate, wrapped by an insulating holder, and housed in the battery case, The current collector contacts the bottom of the battery case via the insulating holder, The insulating holder is composed of a resin sheet, The insulating holder is compressed in the thickness direction at a portion sandwiched between the current collector and the bottom of the battery case. A rectangular secondary battery.

2. The rectangular secondary battery according to claim 1, wherein the current collector is composed of a block body having a thickness in the width direction of the sealing plate.

3. The electrode body is composed of a plurality, The rectangular secondary battery according to claim 1 or 2, wherein edges of the positive electrode plate or the negative electrode plate of each electrode body are connected to the common current collector.

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