Square cylinder battery and battery pack using same

Abstract

The present disclosure is provided with: a metal container (10); a sealing body (30) including an insulating gasket (32) in contact with the container (10); and an electrode group (20) housed in the container (10), the container (10) having a square cylindrical trunk portion (12) including a bottom surface (12t) and a sealing portion (14) continuous with the trunk portion (12), the sealing body (30) being attached to the sealing portion (14), a quadrangle surrounding the trunk portion (12) and having a minimum area of a cross section perpendicular to a direction from the bottom surface (12t) to the sealing portion (14) being a rectangle having long sides and short sides, the sealing part (14) has an elliptical shape or an oblong shape.

Description

Technical Field

[0001] The present disclosure relates to a square-tube battery and a battery pack using the square-tube battery. Background Art

[0002] A cylindrical battery is a battery using a cylindrical container. A square battery is a battery using a square container. For example, Patent Document 1 describes a battery using a metal casing having a main body with a square cross section and a head with a perfect circular cross section.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-115711 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Cylindrical batteries and square batteries are sometimes used in the form of a battery pack containing multiple cylindrical batteries or multiple square batteries. The size and shape required for the battery pack depends on the product in which the battery pack is used. For example, in the case of a car, the size and shape of the battery pack vary depending on the model.

[0008] The present disclosure provides a rectangular cylindrical battery which is suitable for improving the degree of freedom in the size design of a battery pack and has excellent reliability of a sealing portion.

[0009] Means for solving problems

[0010] The present disclosure provides a square tube battery, comprising:

[0011] Metal containers;

[0012] a sealing body, comprising an insulating sealing gasket in contact with the container; and

[0013] an electrode group, contained in the container,

[0014] The container has a main body in a square tube shape including a bottom surface and a sealing portion continuous with the main body.

[0015] The sealing body is installed on the sealing portion,

[0016] The quadrilateral with the smallest cross-section area perpendicular to the height direction from the bottom surface to the sealing portion and surrounding the main body is a rectangle having a long side and a short side.

[0017] The sealing portion has an elliptical shape or an oblong shape.

[0018] Effects of the Invention

[0019] According to the present disclosure, it is possible to provide a rectangular cylindrical battery which is suitable for increasing the degree of freedom in the size design of a battery pack and has excellent reliability of the sealing portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 3D is a three-view diagram of a square battery according to an embodiment of the present disclosure.

[0021] Figure 2 yes Figure 1 A cross-sectional view of the square cylindrical battery along line II-II is shown.

[0022] Figure 3A It is a three-dimensional diagram of the electrode group.

[0023] Figure 3B It is a perspective view of an electrode group according to a modified example.

[0024] Figure 4A The figure shows the shape of a battery pack constructed using a plurality of square cylindrical batteries.

[0025] Figure 4B 1 is a diagram showing the size and shape of a battery pack constructed using a plurality of rectangular batteries according to the present embodiment. DETAILED DESCRIPTION

[0026] (Insights that form the basis of this disclosure)

[0027] The inventors of the present invention have conducted research on batteries that are beneficial to improving the volume energy density of a battery pack. For example, if a plurality of cylindrical batteries are connected in series, in parallel, or in series and parallel to construct a rectangular battery pack, a large dead zone (invalid space) will be generated between the batteries. Therefore, a battery pack using cylindrical batteries is inferior in volume energy density. In contrast, if a rectangular battery pack is constructed by combining a plurality of square batteries, dead zones are not easily generated between the batteries. Therefore, a battery pack using square batteries is advantageous from the perspective of volume energy density. For example, if square batteries are used instead of cylindrical batteries, the volume energy density of the battery pack can be increased by about 25% based on simple calculations.

[0028] As described in Patent Document 1, conventional square batteries have a square cross section. In this case, the longitudinal and transverse dimensions of the battery pack can only be multiples of the length L of one side of the square square battery. For example, when six square square batteries are arranged in a plane to construct a rectangular battery pack, the battery pack can only have two shapes.

[0029] Therefore, the inventors tried to construct a rectangular parallelepiped battery pack by arranging rectangular cylindrical batteries in a plane. In this case, the number of shapes that can be used for the battery pack is greater than that of using square cylindrical batteries. For example, when 6 rectangular cylindrical batteries are arranged in a plane to construct a rectangular parallelepiped battery pack, the battery pack can adopt 4 styles of shapes.

[0030] Here, the inventors have noticed that there are points that should be improved in the shape of the sealing portion of the rectangular square battery. In the case of the previous square battery, a circular sealing portion is formed by drawing, and a circular sealing body is installed on the sealing portion. By forming a circular sealing portion, it is possible to prevent the appearance of a square sealing portion that is difficult to seal. On the one hand, in the case of a rectangular square battery, it is difficult to process the rectangular container in such a way that the sealing portion has a circular cross-section. On the other hand, if the rectangular container is not processed, as described above, the airtightness of the corners of the container will become a problem. Based on such a situation, the inventors thought of the square battery disclosed herein.

[0031] In this specification, a "rectangle" is considered to be a shape having one pair of long sides and one pair of short sides.

[0032] Below, while referring to the attached Figure 1 The present disclosure is not limited to the following embodiments.

[0033] (Implementation Method)

[0034] Figure 1 3D is a three-view diagram of a square battery according to an embodiment of the present disclosure. Figure 2 yes Figure 1 The cross-sectional view of the square cylindrical battery along the II-II line is shown. Figure 1 and Figure 2 As shown, the square battery 100 includes a container 10 and an electrode group 20. The container 10 is made of metal. The electrode group 20 is accommodated in the container 10. The square battery 100 also includes a sealing body 30. The sealing body 30 is installed in the container 10. The container 10 is sealed by the sealing body 30.

[0035] The container 10 has a main body 12 having a square cylindrical shape including a bottom surface 12t and a sealing portion 14 continuous with the main body 12. The main body 12 is a portion that accommodates the electrode group 20. The area of ​​the cross section perpendicular to the height direction of the main body 12 is constant. The sealing portion 14 is a portion where the sealing body 30 is installed.

[0036] The main body 12 has a rectangular cross section. Specifically, the quadrilateral with the smallest area of ​​the cross section perpendicular to the height direction surrounding the main body 12 is a rectangle. Since the main body 12 has a rectangular shape, the square battery 100 is suitable for increasing the degree of freedom in the size design of the battery pack.

[0037] In this specification, the "height direction" is a direction parallel to the direction from the bottom surface 12t to the sealing portion 14. A cross section perpendicular to the height direction may be referred to as a "cross section".

[0038] The sealing portion 14 has an elliptical or oblong shape. Specifically, the sealing portion 14 has a portion in contact with the sealing body 30, and the shape of the portion is elliptical or oblong. The elliptical or oblong sealing portion 14 has no corners, so the container 10 can be reliably sealed. In other words, the sealing portion 14 of the square battery 100 has excellent reliability.

[0039] In this specification, an ellipse means a shape represented by a closed convex curve that does not intersect itself and has two symmetry axes including a minor axis and a major axis. That is, in this specification, shapes that do not strictly satisfy the equation of an ellipse are sometimes included in the concept of an ellipse. An oblong means a shape represented by two semicircles and a set of parallel straight lines. An oblong also has two symmetry axes.

[0040] The long side direction of the cross section of the trunk 12 is consistent with the long side direction of the sealing portion 14 when viewed from above. The elliptical or oblong sealing portion 14 matches the rectangular trunk 12 and can be easily formed by deep drawing of the container 10. The cross section of the sealing portion 14 has an area smaller than that of the cross section of the trunk 12.

[0041] In this embodiment, the sealing portion 14 has a groove portion 14a, a transition portion 14b, and a head portion 14c. In the height direction, the transition portion 14b, the groove portion 14a, and the head portion 14c are arranged in this order.

[0042] The groove 14a is a portion having a support surface 14g protruding toward the inside of the container 10. The groove 14a has an elliptical shape or an oblong shape when viewed from above. Specifically, the inner periphery and the outer periphery of the support surface 14g have an elliptical shape or an oblong shape when viewed from above. The elliptical or oblong groove 14a has no corners, so the container 10 can be reliably sealed. The groove 14a can be formed, for example, by curling.

[0043] The transition portion 14b is a portion located between the main body 12 and the groove portion 14a. The transition portion 14b is connected to the main body 12. The area of ​​the cross section of the transition portion 14b perpendicular to the height direction gradually decreases from the main body 12 to the groove portion 14a. At the transition portion 14b, the shape of the cross section of the sealing portion 14 changes from a rectangle to an ellipse or an oblong. The transition portion 14b can be formed, for example, by deep drawing. By providing the transition portion 14b, the shape of the container 10 can be gradually changed from the main body 12 to the groove portion 14a.

[0044] The dimension H1 of the transition portion 14b in the height direction is larger than the dimension H2 of the groove portion 14a in the height direction. By ensuring a sufficient dimension H1 of the transition portion 14b, a moderate shape change from the trunk portion 12 to the groove portion 14a is allowed.

[0045] The head 14c is a portion that is in close contact with the sealing body 30. The head 14c stands up from the groove 14a in the height direction. The top end of the head 14c, that is, the opening end of the container 10 is bent inward in a manner covering the sealing body 30. In the present embodiment, the sealing body 30 is fixed to the sealing portion 14 by tightening (caulking, caulking) the head 14c. In this way, the inside and outside of the container 10 can be reliably cut off. The cross-section of the head 14c also has an elliptical or oblong shape, so it is not easy for a gap to appear between the head 14c and the sealing body 30. In the present embodiment, a so-called crimp-type sealing structure is adopted.

[0046] The sealing body 30 is a member attached to the sealing portion 14 of the container 10. The sealing body 30 is supported by the support surface 14g of the groove portion 14a. With such a configuration, the sealing body 30 can be prevented from falling into the container 10.

[0047] In the present embodiment, the sealing member 30 has an elliptical shape or an oval shape. Since both the sealing portion 14 and the sealing member 30 have an elliptical shape or an oval shape, the sealing member 30 can be reliably attached to the sealing portion 14 .

[0048] The sealing body 30 includes a sealing plate 31, an insulating gasket 32, a safety valve 33, and a PTC element 34. The sealing plate 31 includes a convex terminal 31a. The insulating gasket 32 ​​is installed around the sealing plate 31. The insulating gasket 32 ​​contacts the support surface 14g of the sealing portion 14. The insulating gasket 32 ​​has an elliptical shape or an oblong shape that matches the sealing portion 14 when viewed from above. Thus, the inside and outside of the container 10 can be reliably cut off.

[0049] In this embodiment, the tip of the head 14c, that is, the opening end of the sealing portion 14 is bent inward and in close contact with the sealing body 30. With this configuration, the sealing body 30 can be reliably prevented from being separated from the container 10, and the container 10 can be reliably sealed.

[0050] The safety valve 33 is built into the sealing body 30, and has a valve core 33a, a spring 33b and an exhaust hole 33c. The valve core 33a is pressed against the exhaust hole 33c by the force of the spring 33b. As a result, the exhaust hole 33c is closed. If the internal pressure of the container 10 rises, the valve core 33a is pushed up, and the exhaust hole 33c is connected to the outside of the battery 100 through the exhaust hole 31h. The PTC element 34 is arranged on the current path between the electrode group 20 and the terminal 31a. The resistance value of the PTC element 34 increases as the temperature of the PTC element 34 increases. If the temperature of the PTC element 34 reaches a predetermined temperature, the resistance of the PTC element 34 rises sharply and cuts off the current.

[0051] like Figure 1 As shown, the sealing plate 31 is provided with a vent hole 31h. In an emergency, the interior of the container 10 communicates with the outside through the safety valve 33 and the vent hole 31h. In this embodiment, a plurality (two) of vent holes 31h are provided along the longitudinal direction of the sealing plate 31.

[0052] The electrode group 20 includes a positive electrode 5, a negative electrode 6, and a pair of separators 7. The electrode group 20 is impregnated with an electrolyte. The opening of the container 10 is blocked by a sealing body 30. The positive electrode 5 includes a positive electrode collector 5a and a positive electrode active material layer 5b. One end of a positive electrode lead 5c is connected to the positive electrode 5. The other end of the positive electrode lead 5c is connected to the back of the sealing body 30. The negative electrode 6 includes a negative electrode collector 6a and a negative electrode active material layer 6b. One end of a negative electrode lead 6c is connected to the negative electrode 6. The other end of the negative electrode lead 6c is connected to the bottom surface of the container 10. Insulating plates 8 are respectively arranged on the upper surface and the lower surface of the electrode group 20.

[0053] The positive lead 5c of the electrode group 20 is electrically connected to the sealing body 30. The width direction of the positive lead 5c is along the long direction of the sealing portion 14 of the elliptical or oval shape. According to such a configuration, the freedom of the width of the positive lead 5c can be increased compared with the sealing portion of a perfect circle. That is, by connecting the positive lead 5c along the long direction of the sealing portion 14, the positive lead 5c with a wide width can be electrically connected to the sealing body 30 compared with the case along the short direction of the sealing portion 14. By using a positive lead 5c with a wide width, a larger current can be flowed.

[0054] The sealing part of the conventional battery is a perfect circle. If the width of the lead is too large, it will be difficult to weld the lead to the sealing body, so it is difficult to increase the width of the lead, and the current that can flow to the lead is also limited. According to the square tube battery 100 of this embodiment, such a problem can also be solved.

[0055] Instead of the positive electrode lead 5c, the negative electrode lead 6c may be connected to the sealing body 30. Accordingly, instead of the negative electrode lead 6c, the positive electrode lead 5c may be connected to the bottom surface of the container 10. That is, in the electrode group 20, the positional relationship between the positive electrode 5 and the negative electrode 6 may be reversed.

[0056] Figure 3A 2 is a three-dimensional diagram of the electrode group 20. Figure 3A As shown, the electrode group 20 has an oblong winding structure. Specifically, the cross section of the electrode group 20 has an oblong shape. According to such a structure, the space inside the container 10 can be reduced, so the volume energy density of the square cylindrical battery 100 can be improved.

[0057] Figure 3B 1 is a perspective view of an electrode group 20a of a modified example. The electrode group 20a has a rectangular winding structure. Specifically, the cross section of the electrode group 20a has a rectangular shape. According to such a structure, the space inside the container 10 can be further reduced. "The cross section is a rectangular shape" means a shape having a pair of parallel short sides and a pair of parallel long sides. The corners of the electrode group 20a are rounded.

[0058] For the same reason, the electrode group 20 may have an elliptical wound structure. In other words, the cross section of the electrode group 20 may have an elliptical shape.

[0059] The electrode group 20 may not have a winding structure. For example, the electrode group 20 may also be a stacked electrode group. A stacked electrode group is an electrode group obtained by stacking plate-shaped constituent units including a positive electrode, a separator, and a negative electrode. In the case of a stacked electrode group, a positive electrode lead is installed on each positive electrode, and a negative electrode lead is installed on each negative electrode. The positive electrode leads are bundled at the root, and the bundled positive electrode leads are welded to the sealing body 14 or the container 20. Similarly, the negative electrode leads are bundled at the root, and the bundled negative electrode leads are welded to the sealing body 14 or the container 20.

[0060] The material of the container 10 is not particularly limited as long as it is a metal. For example, when the container 10 has the same polarity as the negative electrode 6 of the electrode group 20, the container 10 can be made of a steel plate having a Ni-containing layer on the surface. The container 10 may also be made of a so-called nickel-plated steel plate. For example, when the container 10 has the same polarity as the positive electrode 5 of the electrode group 20, the container 10 can be made of Al or an Al alloy. These materials are excellent in processability and are therefore suitable for the material of the container 10 of this embodiment.

[0061] The battery 100 is, for example, a lithium secondary battery. In this case, the electrolyte is placed in the container 10 together with the electrode group 20. However, the type of the rectangular battery 100 is not particularly limited. The rectangular battery 100 may also be other batteries such as a nickel-hydrogen battery.

[0062] Figure 4A is a diagram showing the size and shape of a battery pack constructed using a plurality of square cylindrical batteries. Figure 4A As shown, for example, six square-shaped cylindrical batteries 300 with a length of one side of L are arranged in a plane to construct a rectangular parallelepiped battery pack 400. In this case, the battery pack 400 can only adopt two styles of shapes. One of the two battery packs 400 has a size of 2L×3L. The other of the two battery packs 400 has a size of L×6L.

[0063] Figure 4B 1 is a diagram showing the size and shape of a battery pack constructed using a plurality of rectangular batteries 100 of this embodiment. Figure 4B As shown, for example, six rectangular cylindrical batteries 100 are arranged in a plane to construct a rectangular parallelepiped battery pack 200. In this case, the battery pack 200 can adopt four styles. The rectangular cylindrical battery 100 has a long side of length L1 and a short side of length L2. The four battery packs 200 have sizes of 3L1×2L2, 2L1×3L2, 6L1×L2 and L1×6L2, respectively. In this way, the rectangular cylindrical battery 100 of this embodiment is suitable for increasing the freedom in the size design of the battery pack 200. The rectangular cylindrical battery 100 can be used in battery packs 200 of various shapes, so it has excellent versatility.

[0064] By using a plurality of rectangular batteries 100, the dead space of the battery pack 200 can be significantly reduced. In other words, a battery pack 200 with a high volume energy density can be obtained.

[0065] (Other embodiments)

[0066] (Note)

[0067] The following techniques are disclosed through the description of the above embodiments.

[0068] (Technology 1)

[0069] A square battery, comprising:

[0070] Metal containers;

[0071] a sealing body, comprising an insulating sealing gasket in contact with the container; and

[0072] an electrode group, contained in the container,

[0073] The container has a main body in a square tube shape including a bottom surface and a sealing portion continuous with the main body.

[0074] The sealing body is installed on the sealing portion,

[0075] The quadrilateral with the smallest cross-section area perpendicular to the height direction from the bottom surface to the sealing portion and surrounding the main body is a rectangle having a long side and a short side.

[0076] The sealing portion has an elliptical shape or an oblong shape.

[0077] According to such a configuration, it is possible to provide a rectangular battery which is suitable for increasing the degree of freedom in the size design of the battery pack and has excellent reliability of the sealing portion.

[0078] (Technique 2)

[0079] According to the square-cylinder battery of technology 1, the sealing portion has a groove portion, the groove portion has a support surface protruding into the interior of the container, and the groove portion has an elliptical or oblong shape when viewed from above. The elliptical or oblong groove portion has no corners, so the container can be reliably sealed.

[0080] (Technique 3)

[0081] According to the square-tube battery described in technology 2, the sealing portion has a transition portion located between the main body and the groove portion, and the area of ​​the cross section of the transition portion perpendicular to the height direction gradually decreases from the main body to the groove portion. By providing the transition portion, the shape of the container can be gradually changed from the main body to the groove portion.

[0082] (Technique 4)

[0083] According to the square battery of the second or third aspect, the sealing body is supported by the supporting surface. According to such a configuration, the sealing body can be prevented from falling into the container.

[0084] (Technique 5)

[0085] According to any one of techniques 1 to 3, the lead of the electrode group is electrically connected to the sealing body, and the width direction of the lead is along the length direction of the sealing portion. With such a configuration, the width of the lead can be widened, allowing a larger current to flow through the lead.

[0086] (Technique 6)

[0087] According to any one of the square-shaped batteries of techniques 1 to 3, the opening end of the sealing portion is bent inward and closely attached to the sealing body. With such a configuration, the sealing body can be reliably prevented from being separated from the container, and the container can be reliably sealed.

[0088] (Technique 7)

[0089] According to any one of the square cylindrical batteries of techniques 1 to 6, the sealing body has an elliptical shape or an oblong shape. Since both the sealing portion and the sealing body have an elliptical shape or an oblong shape, the sealing body can be reliably attached to the sealing portion.

[0090] (Technology 8)

[0091] According to any one of techniques 1 to 7, the electrode group has an elliptical, oval or rectangular wound structure. With such a structure, the space inside the container can be reduced, thereby increasing the volume energy density of the battery.

[0092] (Technique 9)

[0093] According to any one of techniques 1 to 8, the container has the same polarity as the negative electrode of the electrode group and is made of a steel plate having a Ni-containing layer on the surface. The steel plate having a Ni-containing layer on the surface is excellent in processability and is therefore suitable as a material for the container of the present disclosure.

[0094] (Technology 10)

[0095] According to any one of techniques 1 to 8, the container has the same polarity as the positive electrode of the electrode group and is made of Al or an Al alloy. Al or an Al alloy is excellent in processability and is therefore suitable as a material for the container of the present disclosure.

[0096] (Technology 11)

[0097] A battery pack includes a plurality of square cylindrical batteries according to any one of techniques 1 to 10. According to the present disclosure, a battery pack with high volume energy density can be obtained.

[0098] Industrial Applicability

[0099] The square cylindrical battery disclosed in the present invention is suitable for a battery pack.

Claims

1. A square battery, comprising: Metal containers; a sealing body, comprising an insulating sealing gasket in contact with the container; and an electrode group, contained in the container, The container has a main body in a square tube shape including a bottom surface and a sealing portion continuous with the main body. The sealing body is installed on the sealing portion, The quadrilateral with the smallest cross-section area perpendicular to the height direction from the bottom surface to the sealing portion and surrounding the main body is a rectangle having a long side and a short side. The sealing portion has an elliptical shape or an oblong shape.

2. The square battery according to claim 1, The sealing portion has a groove portion, and the groove portion has a supporting surface protruding toward the interior of the container. The groove portion has an elliptical shape or an oblong shape in a plan view.

3. The square battery according to claim 2, The sealing portion has a transition portion between the main body portion and the groove portion, An area of ​​a cross section of the transition portion perpendicular to the height direction gradually decreases from the trunk portion toward the groove portion.

4. The square battery according to claim 2, The sealing body is supported by the supporting surface.

5. The square battery according to claim 1, The lead of the electrode group is electrically connected to the sealing body, The width direction of the lead is along the longitudinal direction of the sealing portion.

6. The square battery according to claim 1, The opening end of the sealing portion is bent inwardly and is closely attached to the sealing body.

7. The square battery according to claim 1, The sealing body has an elliptical shape or an oblong shape.

8. The square battery according to claim 1, The electrode group has a wound structure in an elliptical, oblong or rectangular shape.

9. The square battery according to claim 1, The container has the same polarity as the negative electrode of the electrode group and is made of a steel plate having a Ni-containing layer on the surface.

10. The square battery according to claim 1, The container has the same polarity as the positive electrode of the electrode group and is made of Al or an Al alloy.

11. A battery pack comprising a plurality of the square-tube batteries according to claim 1.

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