Insulating plate for battery, and battery

Abstract

A battery 100 according to the present disclosure comprises: a bottomed cylindrical outer can 20; an electrode group 4 that is wound and housed in the outer can 20; a sealing body 3 that seals the outer can 20; and an insulating plate 10 that is disposed between the electrode group 4 and the sealing body 3, or between the electrode group 4 and a bottom portion 21 of the outer can 20. The insulating plate 10 has a disc-shaped central portion 11 and a peripheral edge portion 12 that extends radially outward from the central portion 11. The peripheral edge portion 12 is divided in a direction parallel to a central axis O of the battery 100 to form a first peripheral edge portion 13 that is positioned on a side close to the sealing body 3 and a second peripheral edge portion 14 that is positioned on a side close to the bottom portion 21. The thickness of each of the first peripheral edge portion 13 and the second peripheral edge portion 14 is smaller than the thickness of the central portion 11.

Description

Insulating Plate for Battery and Battery

[0001] The present disclosure relates to an insulating plate for a battery and a battery.

[0002] Conventionally, cylindrical batteries including a bottomed cylindrical outer can, an electrode group accommodated in the outer can, insulating plates respectively positioned above and below the electrode group, and a sealing body closing an opening of the outer can have been widely known.

[0003] A battery may generate heat due to some abnormality, generate gas inside, and cause an increase in internal pressure. In such a case, as described, for example, in Patent Document 1, the sealing body functions as a safety valve that breaks when the internal pressure in the battery rises to enable gas discharge. Patent Document 1 also describes a technique for improving gas exhaust performance when an abnormality occurs in a battery by providing a thin stamped portion that can break when internal pressure rises at the bottom of the outer can of the battery.

[0004] International Publication No. 2016 / 157749

[0005] As described above, when an abnormality occurs in a battery, gas is discharged to the outside. At this time, in order to prevent ignition and spread of fire of the battery, it is desirable that the electrode group is also discharged from the outer can. However, the insulating plate positioned above or below the electrode group is difficult to take out from the outer can, which may hinder discharge of the electrode group. Therefore, in order to improve the safety of batteries, there is a demand for an insulating plate that can be easily taken out from the outer can.

[0006] The present disclosure has been made in view of the foregoing, and an object thereof is to provide a battery capable of improving safety.

[0007] This disclosure provides a battery comprising: a bottomed cylindrical outer casing; a group of electrodes wound around and housed in the outer casing; a sealing body that seals the outer casing; and an insulating plate disposed between the group of electrodes and the sealing body, or between the group of electrodes and the bottom of the outer casing, wherein the insulating plate includes a disc-shaped central portion and a peripheral portion extending radially outward from the central portion, the peripheral portion being divided in a direction parallel to the central axis of the battery to form a first peripheral portion located closer to the sealing body and a second peripheral portion located closer to the bottom of the outer casing, and the thickness of each of the first and second peripheral portions being smaller than the thickness of the central portion.

[0008] The technology disclosed herein can provide a battery that can improve safety.

[0009] Figure 1 is a cross-sectional view of the battery according to this embodiment. Figure 2 is a perspective view of the insulating plate constituting the battery according to this embodiment. Figure 3 is a plan view of the insulating plate constituting the battery according to this embodiment. Figure 4 is a cross-sectional view at the position indicated by the line IV-IV in Figure 3. Figure 5 is a cross-sectional view showing another state of the insulating plate constituting the battery according to this embodiment.

[0010] The embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below.

[0011] In this disclosure, the side with the sealing body is referred to as "up" and the bottom side of the outer casing as "down" in a direction parallel to the central axis of the battery.

[0012] Figure 1 is a cross-sectional view of a battery according to this embodiment. The cross-section in Figure 1 includes the central axis of the battery 100, which is a cylindrical battery. The battery 100 comprises an outer casing 20, an electrode group 4, and a sealing body 3. The electrode group 4 is housed in the outer casing 20. The sealing body 3 seals the opening of the outer casing 20 so as to seal the battery 100.

[0013] The electrode group 4 has a wound structure. The winding axis of the electrode group 4 typically coincides with the central axis of the battery 100. The electrode group 4 has a positive electrode 5, a negative electrode 6, and a pair of separators 7. The electrode group 4 is impregnated with electrolyte. The positive electrode 5 has a positive electrode current collector 5a and a positive electrode active material layer 5b. One end of the 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 surface of the lid 1. The negative electrode 6 has a negative electrode current collector 6a and a negative electrode active material layer 6b. One end of the 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 outer casing 20.

[0014] The sealing body 3 includes a lid 1 and a gasket 2. The lid 1 of the sealing body 3 seals the outer casing 20 via the gasket 2. The lid 1 typically serves as both a terminal and a safety valve. In the battery 100, the back surface of the lid 1 to which the positive electrode lead 5c is connected functions as a terminal. The lid 1 has, for example, a thin, easily breakable portion, so that when the internal pressure of the battery reaches a predetermined pressure, the lid 1 breaks and opens, forming a gas exhaust port in the sealing body 3. This allows for the exhaust of gas and the discharge of contents such as the electrode group. The structure of the lid 1 is not particularly limited as long as it can seal the inside of the battery 100 via the gasket 2, and may, for example, be a structure in which multiple members such as a member that serves as a terminal and a member that serves as a safety valve are stacked. The gasket 2 is positioned between the lid 1 and the opening of the outer casing 20. The gasket 2 is an annular member made of an insulating material such as resin.

[0015] The bottom 21 of the outer casing 20 may have a thin, easily breakable portion, which is, for example, an annular engraved portion 21a centered on the center of the bottom 21. When the internal pressure of the battery reaches a predetermined pressure, the thin portion breaks open, forming a gas exhaust port at the bottom 21. This allows for the exhaust of gas and the discharge of contents such as the electrode group. In this way, the bottom 21 can function as a lower safety valve for the battery.

[0016] The battery 100 comprises an upper insulating plate 8 positioned between the electrode group 4 and the sealing body 3, and a lower insulating plate 9 positioned between the bottom 21 of the outer casing 20 and the electrode group 4. In the battery according to this embodiment, at least one selected from the group consisting of the upper insulating plate 8 and the lower insulating plate 9 is the insulating plate 10 described below.

[0017] Figure 2 is a perspective view of the insulating plate 10 constituting the battery 100 according to this embodiment. Figure 3 is a plan view of the insulating plate 10 constituting the battery 100 according to this embodiment. Figure 3 corresponds to a view of the insulating plate 10 from above in a direction parallel to the central axis of the battery 100. Figure 4 is a cross-sectional view at the position indicated by the line IV-IV in Figure 3.

[0018] The insulating plate 10 includes a disc-shaped central portion 11 and a peripheral portion 12. The peripheral portion 12 extends radially outward from the central portion 11. The peripheral portion 12 is divided in a direction parallel to the central axis O of the battery 100, forming a first peripheral portion 13 located on the side closer to the sealing body 3, i.e., the upper side, and a second peripheral portion 14 located on the side closer to the bottom portion 21, i.e., the lower side. In the insulating plate 10, the thickness W1 of the first peripheral portion 13 and the thickness W2 of the second peripheral portion 14 are each smaller than the thickness W3 of the central portion 11.

[0019] The central axis O of the battery 100 coincides with the winding axis of the electrode group 4. The center of the central portion 11 coincides with the central axis O of the battery 100. The center of the central portion 11 is the center of the circle defined by the boundary between the central portion 11 and the peripheral portion 12. In Figures 2 and 3, the boundary between the central portion 11 and the peripheral portion 12 is shown by a dashed line.

[0020] As shown in Figures 2 to 4, the central portion 11 and the peripheral portion 12 are integral. In the insulating plate 10 shown in Figure 2, the first peripheral portion 13 and the second peripheral portion 14 each surround the entire outer circumference of the central portion 11, and when viewed from a direction parallel to the central axis O, the outer shapes of both the first peripheral portion 13 and the second peripheral portion 14 are circular. That is, in the insulating plate 10, the peripheral portion 12 is divided vertically around the entire circumference of the disc-shaped insulating plate 10. The outer shapes of the first peripheral portion 13 and the second peripheral portion 14 may be circles with the same radius, and the centers of these circles may coincide with the center of the central portion 11.

[0021] The projection image obtained by orthogonally projecting the insulating plate 10 onto a plane perpendicular to the central axis O is preferably circular, and more preferably its center coincides with the central axis O.

[0022] In the insulating plate 10, a slit 15 is formed from the side surface of the peripheral portion 12, i.e., the side surface of the insulating plate 10, to the outer circumference of the central portion 11, so that the peripheral portion 12 is divided in a direction parallel to the central axis O of the battery 100 (vertical direction). The slit 15 separates the peripheral portion 12 into a two-piece structure consisting of a first peripheral portion 13 and a second peripheral portion 14. The first peripheral portion 13 and the second peripheral portion 14 are not bonded together. The first peripheral portion 13, the second peripheral portion 14, and the slit 15 form an annular shape surrounding the central portion 11 in the projected image obtained by orthogonally projecting the battery 100 onto a plane perpendicular to the central axis O.

[0023] As described above, the insulating plate 10 has a two-layer structure in which the peripheral portion 12 is made up of a first peripheral portion 13 and a second peripheral portion 14, both of which are thinner than the central portion 11. The bending rigidity of the plate is proportional to the cube of the plate thickness. Therefore, according to this embodiment, compared to a conventional insulating plate having a single-layer structure of peripheral portion 12 with the same thickness as the central portion 11, the flexibility of the peripheral portion 12 is improved by reducing the rigidity of the first peripheral portion 13 and the second peripheral portion 14. Consequently, the insulating plate 10 is easier to remove from the outer casing 20. This makes it easier to eject the insulating plate 10 in the event of a battery malfunction, allowing the electrode group 4 to be quickly ejected from the high-temperature outer casing 20, thereby reducing abnormal heat generation. Consequently, for example, the risk of battery ignition and the risk of fire spreading can be avoided. In this way, the battery 100 of this embodiment, equipped with the insulating plate 10, has improved safety.

[0024] The insulating plate 10 may be placed between the electrode group 4 and the sealing body 3. That is, the upper insulating plate 8 may be the insulating plate 10. If the direction of gas exhaust when a malfunction occurs in the battery is upward, the upper insulating plate 8 being the insulating plate 10 makes it easier for the upper insulating plate 8 to be discharged, and the electrode group 4 can also be quickly discharged upward, i.e., from the sealing body side. The insulating plate 10 may be placed between the electrode group 4 and the bottom 21 of the outer casing 20. That is, the lower insulating plate 9 may be the insulating plate 10. If the direction of gas exhaust when a malfunction occurs in the battery is downward, the lower insulating plate 9 being the insulating plate 10 makes it easier for the lower insulating plate 9 to be discharged, and the electrode group 4 can also be quickly discharged downward, i.e., from the bottom 21 side. For example, in the battery 100 shown in Figure 1, the bottom 21 is provided with an engraved portion 21a so that the electrode group 4 can be discharged from the bottom 21. Therefore, the discharge of the electrode group 4 can be facilitated by the lower insulating plate 9 being the insulating plate 10.

[0025] As shown in Figure 4, in the battery 100, the first peripheral edge 13 and the second peripheral edge 14 of the insulating plate 10 may be in contact via a slit 15. However, the first peripheral edge 13 and the second peripheral edge 14 are not bonded together. A space may be formed between the first peripheral edge 13 and the second peripheral edge 14; for example, a space open to the outer circumference of the insulating plate 10 may be formed between the first peripheral edge 13 and the second peripheral edge 14. Figure 5 is a cross-sectional view showing another state of the insulating plate constituting the battery according to this embodiment. The insulating plate 10 can be in two states: one in which the first peripheral edge 13 and the second peripheral edge 14 are in contact via a slit 15, as shown in Figure 4, and the outer shape of the insulating plate 10 is disc-shaped; and another in which there is a gap between the first peripheral edge 13 and the second peripheral edge 14, as shown in Figure 5.

[0026] In particular, when the lower insulating plate 9 is an insulating plate 10, a space is created between the first peripheral edge 13 and the second peripheral edge 14, which can improve the circulation of the electrolyte and improve the characteristics of the battery 100.

[0027] When the thickness of the first peripheral portion 13 is defined as W1, the thickness of the second peripheral portion 14 as W2, and the thickness of the central portion 11 as W3, the ratio of the sum of the thicknesses W1 and W2 to the thickness W3, (W1 + W2) / W3, is less than 2.0, may be 1.5 or less, 1.2 or less, and even 1.0 or less. It is desirable that the sum of the thickness W1 of the first peripheral portion 13 and the thickness W2 of the second peripheral portion 14 is 1.0 times or less the thickness W3 of the central portion 11. With this configuration, the overall rigidity of the peripheral portion 12 is reduced compared to a conventional insulating plate having the same thickness. Therefore, the flexibility of the peripheral portion 12 is further improved, making it easier to remove the insulating plate 10 from the outer can 20. (W1 + W2) / W3 may be 0.5 or more, 0.8 or more, and even 1.0 or more. In this way, by making the overall thickness of the peripheral portion 12 equivalent to that of the insulating plate in conventional batteries, the external shape of the insulating plate does not change significantly from that of conventional batteries, and thus the insulating characteristics of the insulating plate 10 can be guaranteed to be the same as in conventional batteries. Thus, the battery 100 of this embodiment can improve safety without affecting the insulating characteristics of the insulating plate 10 or the battery characteristics.

[0028] The ratio W1 / W3 of the thickness of the first peripheral portion 13 to the thickness W3 of the central portion 11 may be 0.1 or more and less than 1.0, 0.2 or more and 0.8 or less, or 0.3 or more and 0.7 or less. The ratio W2 / W3 of the thickness of the second peripheral portion 14 to the thickness W3 of the central portion 11 may be 0.1 or more and less than 1.0, 0.2 or more and 0.8 or less, or 0.3 or more and 0.7 or less.

[0029] The thickness W3 may be, for example, 0.1 mm or more and 0.5 mm or less.

[0030] In a disc-shaped insulating plate 10, when the width of the first peripheral edge 13 is defined as L1 and the width of the second peripheral edge 14 is defined as L2, the ratio L1 / L2 may be 0.8 or more and 1.2 or less, 0.9 or more and 1.1 or less, 0.95 or more and 1.0 or less, or 1.0. In this disclosure, the width of the peripheral edge is the width in the radial direction of the disc and is equal to the length obtained by subtracting the radius of the central portion 11 from the radius of the disc-shaped insulating plate 10. That is, widths L1 and L2 are the lengths from the outer edges of the first peripheral edge 13 and the second peripheral edge 14 to the boundary between the central portion 11 and the peripheral edge 12. When widths L1 and L2 are the same, they coincide with the length in the radial direction of the insulating plate 10 of the slit 15 that divides the peripheral edge 12 into the first peripheral edge 13 and the second peripheral edge 14. Because widths L1 and L2 are the same, the external shape of the insulating plate does not differ significantly from that of a conventional battery, except for the fact that the peripheral portion 12 has a two-layer structure, and thus the same insulation characteristics as conventional batteries can be ensured. Therefore, the battery 100 of this embodiment can improve safety without affecting the insulation characteristics of the insulating plate 10 or the battery characteristics.

[0031] When the upper insulating plate 8 is an insulating plate 10, in the projection image obtained by orthogonally projecting the battery 100 onto a plane perpendicular to the central axis O, it is desirable that the first peripheral portion 13 and the second peripheral portion 14 overlap with the constriction of the opening of the outer casing 20, and more preferably overlap with the easily breakable portion of the sealing body 3. When the lower insulating plate 9 is an insulating plate 10, in the above projection image, it is desirable that it overlaps with the easily breakable portion of the bottom portion 21. It is desirable that the central portion 11 of the insulating plate 10 has a smaller diameter than the opening formed when the easily breakable portion of the sealing body 3 or the bottom portion 21 breaks. That is, it is desirable that the slit 15 that divides the peripheral portion 12 into the first peripheral portion 13 and the second peripheral portion 14 extends further inward (towards the central axis O) than the easily breakable portion of the sealing body 3 or the easily breakable portion of the bottom portion 21. With such a configuration, it becomes easier to remove the insulating plate 10 from the outer casing 20. Therefore, in the event of a battery malfunction, the electrode group 4 can be discharged from the outer casing 20 more quickly along with the exhaust gas, thus improving safety.

[0032] The ratio of the width L1 of the first peripheral edge 13 to the radius of the insulating plate 10 may be, for example, 10% or more and 30% or less, or 15% or more and 20% or less. The ratio of the width L2 of the second peripheral edge 14 to the radius of the insulating plate 10 may be, for example, 10% or more and 30% or less, or 15% or more and 20% or less.

[0033] The insulating plate 10 may have holes for gas venting. The insulating plate 10 shown in Figures 2 to 5 has a hole 16 in the center. The hole 16 is a through hole. The number and shape of the holes in the insulating plate 10 are not particularly limited.

[0034] The insulating plate 10 may be made of an insulating material such as glass fiber reinforced phenolic resin (glass phenolic resin) or polypropylene.

[0035] The insulating plate 10 may be manufactured, for example, by making cuts from the side toward the center in a direction parallel to the plane of the disc on the peripheral edge of the disc-shaped insulating material. In this manufacturing method, the insulating plate 10 obtained typically has the same length L1 for the first peripheral portion 13 and the same length L2 for the second peripheral portion 14. Also, the sum of the thickness W1 of the first peripheral portion 13 and the thickness W2 of the second peripheral portion 14 is the same as the thickness W3 of the central portion 11.

[0036] The insulating plate 10 may be manufactured by stacking two disc-shaped insulating materials and bonding their central portions together so that their peripheral edges are not bonded. In this manufacturing method, the resulting insulating plate 10 has a structure in which a layer including the first peripheral portion 13 and a layer including the second peripheral portion 14 are laminated in a direction along the central axis O. Also, the sum of the thickness W1 of the first peripheral portion 13 and the thickness W2 of the second peripheral portion 14 is the same as the thickness W3 of the central portion.

[0037] (Other Embodiments) (Note) The above description of embodiments discloses the following technologies.

[0038] (Technical 1) A battery comprising: a bottomed cylindrical outer can; a group of electrodes wound and housed in the outer can; a sealing body that seals the outer can; and an insulating plate disposed between the group of electrodes and the sealing body, or between the group of electrodes and the bottom of the outer can, wherein the insulating plate includes a disc-shaped central portion and a peripheral portion extending radially outward from the central portion, the peripheral portion being divided in a direction parallel to the central axis of the battery to form a first peripheral portion located closer to the sealing body and a second peripheral portion located closer to the bottom of the outer can, and the thickness of each of the first and second peripheral portions being smaller than the thickness of the central portion.

[0039] According to the technology disclosed herein, the flexibility of the peripheral edge of the insulating plate is improved, making it easier to remove the insulating plate from the outer casing. As a result, if a malfunction occurs in the battery, the insulating plate can be easily ejected, allowing the electrode group to be quickly removed from the high-temperature outer casing, thereby reducing the heat generated by the battery. Thus, the battery of technology 1 has improved safety.

[0040] (Technical 2) The battery according to Technical 1, wherein, when viewed from a direction parallel to the central axis, the outer shape of the first peripheral edge and the outer shape of the second peripheral edge are both circular. With the above configuration, the insulating plate can be easily removed from the outer casing, and the safety of the battery can be improved.

[0041] (Technology 3) The battery according to Technology 1 or 2, wherein the sum of the thickness of the first peripheral portion and the thickness of the second peripheral portion is 1.0 times or less the thickness of the central portion. With the above configuration, the insulating plate can be easily removed from the outer casing, and the safety of the battery can be improved. Furthermore, according to Technology 3, the outer shape of the insulating plate can be made the same as that of a conventional battery, and the insulating plate can be guaranteed to have the same insulating properties as a conventional battery.

[0042] (Technical 4) A battery according to any one of Technical 1 to 3, wherein the width of the first peripheral portion and the width of the second peripheral portion are the same. With the above configuration, the insulating plate can be easily removed from the outer casing, and the safety of the battery can be improved. In addition, the manufacturing of the insulating plate may be made easier.

[0043] (Aspect 5) The battery according to any one of Aspects 1 to 4, wherein the insulating plate is disposed between the electrode group and the sealing body. According to the above configuration, the insulating plate and the electrode group can be easily taken out from the top of the outer can. Aspect 5 is suitable for a battery in which the exhaust direction is upward.

[0044] (Aspect 6) The battery according to any one of Aspects 1 to 5, wherein the insulating plate is disposed between the electrode group and the bottom portion of the outer can. According to the above configuration, the insulating plate and the electrode group can be easily taken out from the bottom side of the outer can. Aspect 6 is suitable for a battery in which the exhaust direction is downward.

[0045] (Aspect 7) An insulating plate for a battery, comprising: a disk-shaped central portion; and a peripheral edge portion extending radially outward from the central portion, wherein the peripheral edge portion is divided in a thickness direction of the insulating plate for a battery to form a first peripheral edge portion and a second peripheral edge portion, and a thickness of each of the first peripheral edge portion and the second peripheral edge portion is smaller than a thickness of the central portion.

[0046] In the event that an abnormality occurs in the battery, the insulating plate for a battery according to Aspect 7 is easily discharged and does not hinder discharge of the electrode group, so the electrode group can be quickly discharged from the high-temperature outer can, and heat generation of the battery can be reduced. Therefore, according to Aspect 7, a battery with improved safety can be provided.

[0047] (Aspect 8) The insulating plate for a battery according to Aspect 7, wherein when viewed from a direction perpendicular to a main surface of the central portion, both an outer shape of the first peripheral edge portion and an outer shape of the second peripheral edge portion are circular. According to the above configuration, a battery with improved safety can be provided.

[0048] (Aspect 9) The insulating plate for a battery according to Aspect 7 or 8, wherein a sum of the thickness of the first peripheral edge portion and the thickness of the second peripheral edge portion is not more than 1.0 times the thickness of the central portion. According to the above configuration, a battery with improved safety can be provided. In addition, since the outer shape of the insulating plate for a battery according to Aspect 9 does not greatly differ from that of an insulating plate in a conventional battery, insulation characteristics equivalent to those of the conventional art can be ensured.

[0049] (Technical 10) A battery insulating board according to any one of Technical 7 to 9, wherein the width of the first peripheral edge and the width of the second peripheral edge are the same. With the above configuration, a battery with improved safety can be provided. Furthermore, the battery insulating board of Technical 10 can be easily manufactured.

[0050] The technology disclosed herein is useful for cylindrical secondary batteries such as lithium-ion batteries and sodium-ion batteries.

Claims

1. A battery comprising: a bottomed cylindrical outer casing; a group of electrodes wound around and housed in the outer casing; a sealing body that seals the outer casing; and an insulating plate disposed between the group of electrodes and the sealing body, or between the group of electrodes and the bottom of the outer casing, wherein the insulating plate includes a disc-shaped central portion and a peripheral portion extending radially outward from the central portion, the peripheral portion being divided in a direction parallel to the central axis of the battery to form a first peripheral portion located closer to the sealing body and a second peripheral portion located closer to the bottom of the outer casing, and the thickness of each of the first and second peripheral portions being smaller than the thickness of the central portion.

2. The battery according to claim 1, wherein, when viewed from a direction parallel to the central axis, the outer shape of the first peripheral portion and the outer shape of the second peripheral portion are both circular.

3. The battery according to claim 1, wherein the sum of the thickness of the first peripheral portion and the thickness of the second peripheral portion is 1.0 times or less the thickness of the central portion.

4. The battery according to claim 1, wherein the width of the first peripheral portion and the width of the second peripheral portion are the same.

5. The battery according to claim 1, wherein the insulating plate is disposed between the electrode group and the sealing body.

6. The battery according to claim 1, wherein the insulating plate is disposed between the electrode group and the bottom of the outer casing.

7. A battery insulating plate comprising a disc-shaped central portion and a peripheral portion extending radially outward from the central portion, wherein the peripheral portion is divided in the thickness direction of the battery insulating plate to form a first peripheral portion and a second peripheral portion, and the thickness of each of the first peripheral portion and the second peripheral portion is smaller than the thickness of the central portion.

8. The battery insulating plate according to claim 7, wherein, when viewed from a direction perpendicular to the main surface of the central portion, the outer shape of the first peripheral portion and the outer shape of the second peripheral portion are both circular.

9. The battery insulating board according to claim 7, wherein the sum of the thickness of the first peripheral portion and the thickness of the second peripheral portion is 1.0 times or less the thickness of the central portion.

10. The battery insulating plate according to claim 7, wherein the width of the first peripheral edge and the width of the second peripheral edge are the same.

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