Battery module

Abstract

This technology provides a way to suppress abnormal temperature increases in battery modules. [Solution] The battery module comprises a battery element, a first current collector electrically connected to the battery element, a second current collector positioned opposite the first current collector and electrically connected to the first current collector, and a plurality of resin insulators positioned between the first and second current collectors. The battery element comprises a positive electrode, a negative electrode, and a resin separator positioned between the positive and negative electrodes. The first and second current collectors are electrically insulated by the insulators in the portion between them, and electrically connected in the portion between them where the insulators are not positioned. The melting point of the resin insulators is lower than the melting point of the resin in the separators. The insulators melt as the first and second current collectors generate heat due to current flow and spread between the first and second current collectors.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a battery module.

Background Art

[0002] A battery module is disclosed in Patent Document 1. The battery module of Patent Document 1 includes a first current collector, a second current collector electrically connected to the first current collector, a plurality of insulators disposed between the first current collector and the second current collector, and a battery element electrically connected to the first current collector. The first current collector and the second current collector are electrically insulated by the insulator at a portion where the insulator is disposed therebetween, and are electrically connected at a portion where the insulator is not disposed therebetween.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a battery module, an excessive current may flow due to, for example, an external short circuit or the like. Then, the battery module may become abnormally hot, and it is conceivable that the battery element may be damaged due to this. Therefore, this specification provides a technology capable of suppressing an abnormal temperature rise of the battery module.

Means for Solving the Problems

[0005] In a first aspect of this technology, a battery module comprises a battery element, a first current collector electrically connected to the battery element, a second current collector positioned opposite the first current collector and electrically connected to the first current collector, and a plurality of resin insulators positioned between the first and second current collectors. The battery element comprises a positive electrode, a negative electrode, and a resin separator positioned between the positive and negative electrodes. The first and second current collectors are electrically insulated by the insulators in the portions between them, and electrically connected in the portions between them where the insulators are not positioned. The melting point of the resin of the insulators is lower than the melting point of the resin of the separators. The insulators melt and spread between the first and second current collectors as the first and second current collectors generate heat due to current flow.

[0006] In this configuration, if the first and second current collectors overheat due to excessive current flowing through the battery module, the insulator melts and spreads between the first and second current collectors. This interrupts or suppresses the current flow between the first and second current collectors. As a result, excessive current flowing through the battery module can be suppressed, and an abnormal temperature rise in the battery module can be prevented. Furthermore, the melting of the insulator before the separator can protect the battery elements.

[0007] In a second embodiment, in the first embodiment, the thickness of the insulator may be thinner than the thickness of the first current collector and thinner than the thickness of the second current collector.

[0008] In a third embodiment, in the first or second embodiment, the plurality of insulators may be arranged in a first direction and extend in a second direction different from the first direction.

[0009] In the fourth embodiment, in the third embodiment, the width of the insulator in the first direction may be narrower than the width between adjacent insulators in the first direction.

[0010] In the fifth embodiment, in any one of the first to fourth embodiments, the melting point of the resin of the insulator may be higher than the upper limit of the normal operating temperature of the battery module. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram showing the battery module of the embodiment. [Figure 2] Cross-sectional view II-II in Figure 1. [Figure 3] A schematic diagram showing the battery module of the embodiment. [Modes for carrying out the invention]

[0012] The battery module 2 of the embodiment will be described with reference to the drawings. As shown in Figure 1, the battery module 2 of the embodiment comprises a plurality of battery elements 10 and an outer casing 30 that houses the plurality of battery elements 10. The battery module 2 also includes a positive electrode first current collector 20 and a negative electrode first current collector 22 for each of the plurality of battery elements 10 that collect electricity generated by the battery element 10. The battery module 2 also includes a positive electrode second current collector 50 and a negative electrode second current collector 52 that collect electricity generated by the plurality of battery elements 10. Furthermore, the battery module 2 comprises a plurality of positive electrode insulators 40 arranged between the positive electrode first current collector 20 and the positive electrode second current collector 50, and a plurality of negative electrode insulators 42 arranged between the negative electrode first current collector 22 and the negative electrode second current collector 52.

[0013] Multiple battery elements 10 are stacked inside the outer casing 30 and electrically connected in series. Each battery element 10 constitutes, for example, a lithium-ion battery. Each battery element 10 includes a positive electrode 12, a negative electrode 14, and a separator 16 positioned between the positive electrode 12 and the negative electrode 14. Each battery element 10 also includes an electrolyte 18.

[0014] Multiple battery elements 10 are arranged such that the positive electrode 12 of one battery element 10 faces the negative electrode 14 of the other battery element 10. Multiple battery elements 10 are arranged such that each positive electrode 12 faces one direction (upward in Figure 1) and each negative electrode 14 faces the other direction (downward in Figure 1).

[0015] The positive electrode 12 of the battery element 10 is provided on the surface of the positive electrode first current collector 20. The positive electrode 12 is coated onto the surface of the positive electrode first current collector 20. The positive electrode 12 is manufactured, for example, by coating the surface of the positive electrode first current collector 20 with a paste containing a positive electrode active material and then drying it. The positive electrode active material, which is the material of the positive electrode 12, is not particularly limited, but is for example lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), etc. The method for manufacturing the positive electrode 12 is also not particularly limited.

[0016] The negative electrode 14 of the battery element 10 is provided on the surface of the negative electrode first current collector 22. The negative electrode 14 is coated onto the surface of the negative electrode first current collector 22. The negative electrode 14 is manufactured, for example, by coating the surface of the negative electrode first current collector 22 with a paste containing a negative electrode active material and then drying it. The negative electrode active material, which is the material of the negative electrode 14, is not particularly limited, but is such as graphite, hard carbon, or soft carbon. The method for manufacturing the negative electrode 14 is also not particularly limited.

[0017] The separator 16 is made in film form from an ion-conductive resin. The separator 16 is made from, for example, polypropylene (PP), polyethylene (PE), or a combination thereof. The thickness of the separator 16 is, for example, 20 μm. The peripheral edge of the separator 16 is fixed to the support 32 located inside the outer casing 30.

[0018] The electrolyte 18 is filled between the positive electrode 12 and the separator 16 of the battery element 10, and between the negative electrode 14 and the separator 16. The electrolyte 18 is a liquid containing an electrolyte. The electrolyte is, for example, a lithium salt such as LiPF6, LiClO4, LiBF4, etc., but is not particularly limited.

[0019] The first positive electrode current collector 20 is made of a conductive metal. The first positive electrode current collector 20 is, for example, made of a metal containing aluminum (Al) in a foil shape. The thickness of the first positive electrode current collector 20 is, for example, 100 μm or less. The first positive electrode current collector 20 is electrically connected to the battery element 10 and collects the electricity generated by the battery element 10. The first positive electrode current collector 20 is electrically connected to the positive electrode 12 of the battery element 10 and collects electricity from the positive electrode 12. The peripheral portion of the first positive electrode current collector 20 is fixed to the support 32 disposed inside the exterior body 30.

[0020] The first negative electrode current collector 22 is made of a conductive metal. The first negative electrode current collector 22 is, for example, made of a metal containing copper (Cu) in a foil shape. The thickness of the first negative electrode current collector 22 is, for example, 100 μm or less. The first negative electrode current collector 22 is electrically connected to the battery element 10 and collects the electricity generated by the battery element 10. The first negative electrode current collector 22 is electrically connected to the negative electrode 14 of the battery element 10 and collects electricity from the negative electrode 14. The peripheral portion of the first negative electrode current collector 22 is fixed to the support 32 disposed inside the exterior body 30.

[0021] Among the plurality of first positive electrode current collectors 20 and the plurality of first negative electrode current collectors 22, the opposing first positive electrode current collector 20 and the first negative electrode current collector 22 are integrated by being bonded together. The opposing first positive electrode current collector 20 and the first negative electrode current collector 22 are electrically connected. The opposing first positive electrode current collector 20 and the first negative electrode current collector 22 may be integrally manufactured in advance.

[0022] The second positive current collector 50 is made of a conductive metal. The second positive current collector 50 is, for example, made into a foil shape from a metal containing aluminum (Al). The thickness of the second positive current collector 50 is, for example, 100 μm or less. The second positive current collector 50 is electrically connected to the battery element 10 via the first positive current collector 20, and collects the electricity generated by the battery element 10. The second positive current collector 50 is electrically connected to the outermost (upper side in FIG. 1) first positive current collector 20 among the plurality of first positive current collectors 20, and collects electricity from that first positive current collector 20. The peripheral portion of the second positive current collector 50 is fixed to the exterior body 30.

[0023] The second negative current collector 52 is made of a conductive metal. The second negative current collector 52 is, for example, made into a foil shape from a metal containing copper (Cu). The thickness of the second negative current collector 52 is, for example, 100 μm or less. The second negative current collector 52 is electrically connected to the battery element 10 via the first negative current collector 22, and collects the electricity generated by the battery element 10. The second negative current collector 52 is electrically connected to the outermost (lower side in FIG. 1) first negative current collector 22 among the plurality of first negative current collectors 22, and collects electricity from that first negative current collector 22. The peripheral portion of the second negative current collector 52 is fixed to the exterior body 30.

[0024] The support 32 disposed inside the exterior body 30 supports the first positive current collector 20, the first negative current collector 22, and the separator 16. The support 32 seals the portion filled with the electrolyte 18 of the battery element 10. That is, the support 32 seals between the first positive current collector 20 and the separator 16, and between the first negative current collector 22 and the separator 16. The support 32 is made of an insulating resin. The support 32 is, for example, made from polypropylene (PP), polyethylene (PE), or a combination thereof.

[0025] The casing 30 houses the battery element 10 and the support 32 that supports the battery element 10. The casing 30 surrounds the battery element 10 and the support 32. The casing 30 is made of an insulating resin. The casing 30 is made of, for example, polypropylene (PP), polyethylene (PE), or a combination thereof.

[0026] The casing 30 includes a positive electrode side opening 33a that opens on the positive electrode side of the battery element 10, and a negative electrode side opening 33b that opens on the negative electrode side of the battery element 10. A positive electrode second current collector 50 is positioned in the positive electrode side opening 33a. The positive electrode second current collector 50 closes the positive electrode side opening 33a. The peripheral edge of the positive electrode second current collector 50 is fixed to the casing 30. Similarly, a negative electrode second current collector 52 is positioned in the negative electrode side opening 33b. The negative electrode second current collector 52 closes the negative electrode side opening 33b. The peripheral edge of the negative electrode second current collector 52 is fixed to the casing 30.

[0027] Next, the multiple positive electrode insulators 40 arranged between the positive electrode first current collector 20 and the positive electrode second current collector 50 will be described. The multiple positive electrode insulators 40 are provided along the surface of the positive electrode first current collector 20 (upper surface in Figure 1) and along the surface of the positive electrode second current collector 50 (lower surface in Figure 1).

[0028] The positive electrode first current collector 20 and the positive electrode second current collector 50 are in close contact with multiple positive electrode insulators 40 sandwiched between them. The positive electrode first current collector 20 and the positive electrode second current collector 50 are in close contact via the multiple positive electrode insulators 40 when the outer casing 30 is formed by vacuum forming. The positive electrode first current collector 20 and the positive electrode second current collector 50 are separated by the positive electrode insulators 40 in the areas where the positive electrode insulators 40 are placed, and are in contact in the areas where the positive electrode insulators 40 are not placed. The positive electrode first current collector 20 and the positive electrode second current collector 50 are electrically insulated by the positive electrode insulators 40 in the areas where the positive electrode insulators 40 are placed, and are electrically connected in the areas where the positive electrode insulators 40 are not placed.

[0029] As shown in Figure 2, the multiple positive electrode insulators 40 are arranged in a striped pattern. The multiple positive electrode insulators 40 are arranged side by side with spacing in a first direction (the X direction in Figure 2). Each positive electrode insulator 40 extends in a second direction (the Y direction in Figure 2) perpendicular to the first direction. The width W1 of each positive electrode insulator 40 in the first direction is narrower than the width W2 between adjacent positive electrode insulators 40 in the first direction. For example, W1 ≤ 0.3W2.

[0030] Each positive electrode insulator 40 is manufactured in film form. The thickness of the positive electrode insulator 40 is, for example, 20 μm. The thickness of the positive electrode insulator 40 is thinner than the thickness of the positive electrode first current collector 20 and thinner than the thickness of the positive electrode second current collector 50. The thickness of the positive electrode insulator 40 is, for example, 20% or less of the thickness of the positive electrode first current collector 20. The thickness of the positive electrode insulator 40 is, for example, 20% or less of the thickness of the positive electrode second current collector 50.

[0031] Each positive electrode insulator 40 is made from a resin. The positive electrode insulator 40 is made from, for example, low-density polyethylene (PE), high-density polyethylene (PE), polypropylene (PP), or a combination of several of these resins. The melting point of low-density polyethylene (PE) is approximately 100°C to 115°C. The melting point of high-density polyethylene (PE) is approximately 125°C to 140°C. The melting point of polypropylene (PP) is approximately 160°C. The melting point of the resin of the positive electrode insulator 40 is lower than the melting point of the resin of the separator 16 of the battery element 10. For example, the melting point of the resin of the positive electrode insulator 40 is at least 20°C lower than the melting point of the resin of the separator 16 of the battery element 10.

[0032] Furthermore, the melting point of the resin of the positive electrode insulator 40 may be, for example, higher than the upper limit of the normal operating temperature of the battery module 2. For example, the melting point of the resin of the positive electrode insulator 40 is 20°C or more higher than the upper limit of the normal operating temperature of the battery module 2. The normal operating temperature of the battery module 2 may be, for example, a temperature controlled by the cooling system (not shown) of the battery module 2, taking into consideration the lifespan and safety of the battery module 2. The upper limit of the normal operating temperature of the battery module 2 is, for example, 70°C.

[0033] Furthermore, the melting point of the resin of the positive electrode insulator 40 may be lower than, for example, the overheating mode generation temperature. For example, the melting point of the resin of the positive electrode insulator 40 may be 40°C or more lower than the overheating mode generation temperature. The overheating mode generation temperature may be set to, for example, the same temperature as the melting point of the resin of the separator 16 of the battery element 10.

[0034] The configuration of the multiple negative electrode insulators 42 positioned between the first negative electrode current collector 22 and the second negative electrode current collector 52 is the same as that of the multiple positive electrode insulators 40 positioned between the first positive electrode current collector 20 and the second positive electrode current collector 50, so a detailed explanation will be omitted. The configuration of the negative electrode insulators 42 will be explained by replacing "positive electrode" with "negative electrode" in the above description of the positive electrode insulators 40.

[0035] In the battery module 2 described above, when multiple battery elements 10 generate electricity, current flows through the positive electrode first current collector 20 and the positive electrode second current collector 50, causing the positive electrode first current collector 20 and the positive electrode second current collector 50 to heat up due to the current flow. In the battery module 2, when the positive electrode first current collector 20 and the positive electrode second current collector 50 heat up, the temperature of the multiple positive electrode insulators 40 placed between the positive electrode first current collector 20 and the positive electrode second current collector 50 also rises. Each positive electrode insulator 40 melts when its temperature exceeds its melting point.

[0036] As shown in Figure 3, the multiple positive electrode insulators 40 positioned between the positive electrode first current collector 20 and the positive electrode second current collector 50 melt and spread laterally between the positive electrode first current collector 20 and the positive electrode second current collector 50. This expands the area insulated between the positive electrode first current collector 20 and the positive electrode second current collector 50 by the multiple positive electrode insulators 40. Consequently, the resistance between the positive electrode first current collector 20 and the positive electrode second current collector 50 increases. As a result, the current flowing through the positive electrode first current collector 20 and the positive electrode second current collector 50 is attenuated or interrupted.

[0037] The above explanation described the positive electrode side of battery module 2, but the negative electrode side is the same. The negative electrode side can be explained by replacing "positive electrode" with "negative electrode" in the above explanation.

[0038] (effect) The battery module 2 of the embodiment has been described above. As is clear from the above description, the battery module 2 comprises a positive electrode first current collector 20 electrically connected to the battery element 10, and a positive electrode second current collector 50 positioned opposite the positive electrode first current collector 20 and electrically connected to the positive electrode first current collector 20. The battery module 2 also comprises a plurality of resin positive electrode insulators 40 positioned between the positive electrode first current collector 20 and the positive electrode second current collector 50. The battery element 10 comprises a positive electrode 12, a negative electrode 14, and a resin separator 16 positioned between the positive electrode 12 and the negative electrode 14. The melting point of the resin of the positive electrode insulator 40 is lower than the melting point of the resin of the separator 16. The positive electrode insulator 40 melts when the positive electrode first current collector 20 and the positive electrode second current collector 50 generate heat due to the flow of current, and spreads between the positive electrode first current collector 20 and the positive electrode second current collector 50.

[0039] In this configuration, if an excessive current flows through the battery module 2, causing the positive electrode first current collector 20 and the positive electrode second current collector 50 to overheat abnormally, the positive electrode insulator 40 will melt and spread between the positive electrode first current collector 20 and the positive electrode second current collector 50. This will interrupt or suppress the current flow between the positive electrode first current collector 20 and the positive electrode second current collector 50. As a result, an excessive current flow through the battery module 2 can be suppressed, and an abnormal temperature rise in the battery module 2 can be suppressed. In addition, the battery element 10 can be protected by the melting of the positive electrode insulator 40 before the separator 16 melts.

[0040] The thickness of the positive electrode insulator 40 is thinner than the thickness of the positive electrode first current collector 20 and also thinner than the thickness of the positive electrode second current collector 50. With this configuration, the positive electrode first current collector 20 and the positive electrode second current collector 50 can be made to make good contact under normal conditions. In addition, the overall thickness of the battery module 2 can be reduced.

[0041] Multiple positive electrode insulators 40 are arranged in a first direction (X direction in Figure 2) and extend in a second direction (Y direction in Figure 2) that is different from the first direction. With this configuration, multiple positive electrode insulators 40 can be easily manufactured.

[0042] The width W1 of the positive electrode insulator 40 in the first direction is narrower than the width W2 between adjacent positive electrode insulators 40 in the first direction. With this configuration, the positive electrode first current collector 20 and the positive electrode second current collector 50 can be in good contact under normal conditions.

[0043] The above explanation described the positive electrode side of battery module 2, but the negative electrode side is the same. The negative electrode side can be explained by replacing "positive electrode" with "negative electrode" in the above explanation.

[0044] (modified version) (1) In the above embodiment, the multiple positive electrode insulators 40 were arranged in a striped pattern, but the arrangement is not particularly limited. The multiple positive electrode insulators 40 only need to be arranged with some space between them. The same applies to the multiple negative electrode insulators 42.

[0045] (2) In the above embodiment, the direction in which the multiple positive electrode insulators 40 are aligned (first direction) and the direction in which each positive electrode insulator 40 extends (second direction) were orthogonal, but the configuration is not limited to this. The first direction and the second direction do not have to be orthogonal.

[0046] (3) The difference between the melting point of the resin of the positive electrode insulator 40 and the melting point of the separator 16 of the battery element 10 may be greater than the difference between the melting point of the resin of the positive electrode insulator 40 and the upper limit of the normal operating temperature of the battery module 2. With this configuration, abnormal temperature rises of the battery module 2 can be further suppressed.

[0047] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0048] 2: Battery module, 10: Battery element, 12: Positive electrode, 14: Negative electrode, 16: Separator, 18: Electrolyte, 20: Positive electrode first current collector, 22: Negative electrode first current collector, 30: Outer casing, 32: Support, 33a: Positive electrode side opening, 33b: Negative electrode side opening, 40: Positive electrode insulator, 42: Negative electrode insulator, 50: Positive electrode second current collector, 52: Negative electrode second current collector

Claims

1. Battery elements, A first current collector electrically connected to the aforementioned battery element, A second current collector is positioned opposite the first current collector and is electrically connected to the first current collector, It comprises a plurality of resin insulators disposed between the first current collector and the second current collector, The aforementioned battery element comprises a positive electrode, a negative electrode, and a resin separator disposed between the positive electrode and the negative electrode. The first current collector and the second current collector are electrically insulated by the insulator in the portion between them where the insulator is placed, and are electrically connected in the portion between them where the insulator is not placed. The melting point of the resin of the insulator is lower than the melting point of the resin of the separator. The insulator melts when the first current collector and the second current collector generate heat due to the flow of current, and spreads between the first current collector and the second current collector in a battery module.

2. The battery module according to claim 1, wherein the thickness of the insulator is thinner than the thickness of the first current collector and thinner than the thickness of the second current collector.

3. The battery module according to claim 1 or 2, wherein the plurality of insulators are arranged in a first direction and extend in a second direction different from the first direction.

4. The battery module according to claim 3, wherein the width of the insulator in the first direction is narrower than the width between adjacent insulators in the first direction.

5. The battery module according to claim 1 or 2, wherein the melting point of the resin of the insulator is higher than the upper limit of the normal operating temperature of the battery module.

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