Battery module

Abstract

To provide a battery module in which irreversible movement of lithium metal in a battery cell can be suppressed.SOLUTION: A battery module includes a battery cell 1, a pair of pressurizing plates 2 that sandwich the battery cell 1 from a thickness direction to pressurize the battery cell 1, and a connecting part 3 that connects the pressurizing plates 2 while the pressurizing plates 2 pressurize the battery cell 1. The connecting part 3 includes a first connecting member 31 that is connected to one (pressurizing plate 2A) of the pressurizing plates 2, a second connecting member 32 that is connected to the other (pressurizing plate 2B) of the pressurizing plates 2, and a junction 33 that joins the first connecting member 31 and the second connecting member 32. The junction 33 is heated by heat transferred from the battery cell 1 through the pressurizing plate 2A and the first connecting member 31 or heat transferred from the battery cell 1 through the pressurizing plate 2B and the second connecting member 32, and, when the temperature of the junction 33 exceeds a predetermined temperature, the junction melts and releases the joining between the first connecting member 31 and the second connecting member 32.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a battery module.

Background Art

[0002] Patent Document 1 discloses a structure in which battery cells are sandwiched in the thickness direction and pressure is applied to the battery cells.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when lithium metal is used for the negative electrode in a battery cell, if the battery cell reaches a predetermined temperature or higher, lithium may soften and irreversibly move outside a predetermined range.

[0005] An object of the present invention is to provide a battery module that suppresses irreversible movement of lithium metal in a battery cell.

Means for Solving the Problems

[0006] The battery module according to the present invention includes a battery cell, a pair of pressing plates that sandwich the battery cell in the thickness direction to press the battery cell, and a connecting portion that connects the pair of pressing plates in a state where the pair of pressing plates press the battery cell. The connecting portion includes a first connecting member connected to one of the pair of pressing plates, a second connecting member connected to the other of the pair of pressing plates, and a joining portion disposed between the first connecting member and the second connecting member to join the first connecting member and the second connecting member. And the joining portion is heated by heat transmitted from the battery cell through one of the pressing plates and the first connecting member, or heat transmitted from the battery cell through the other of the pressing plates and the second connecting member, and further melts when the temperature of the joining portion exceeds a predetermined temperature to release the joining between the first connecting member and the second connecting member.

Effect of the Invention

[0007] According to the present invention, when the battery cell becomes high temperature, the lithium metal in the battery cell softens. In this case, the joining portion melts due to the heat transmitted from the battery cell, and the joining between the first connecting member and the second connecting member is released, so that the pressure on the battery cell is released. Therefore, irreversible movement of the lithium metal in the battery cell can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] [First Embodiment] Fig. 1 is a plan view of a battery module 100 according to the first embodiment. Fig. 2 is a cross-sectional view taken along line A-A of Fig. 1. The battery module 100 according to the first embodiment includes a battery cell 1, a pair of pressure plates 2 (pressure plate 2A, pressure plate 2B) that sandwich the battery cell 1 in the thickness direction, and a connecting portion 3 that connects the pair of pressure plates 2. In Fig. 1, the illustration of the upper pressure plate 2A shown in Fig. 2 is omitted.

[0011] The battery cell 1 is, for example, an all-solid-state battery, which is a laminate obtained by laminating a laminate body of a positive electrode current collector foil (not shown), a positive electrode layer (not shown), a solid electrolyte layer (not shown), a negative electrode layer (not shown), and a negative electrode current collector foil (not shown) in this order and then laminating and packaging it. A positive electrode tab (electrode tab 11) extends from the positive electrode current collector foil and is exposed from the exterior material. Similarly, a negative electrode tab (electrode tab 11) extends from the negative electrode current collector foil and is exposed from the exterior material. The two electrode tabs 11 extend in parallel from the same short side (side surface) of the battery cell 1.

[0012] The positive electrode current collector foil is a thin plate formed of a metal such as aluminum (Al). The negative electrode current collector foil is a thin plate formed of a metal such as stainless steel (SUS) or copper (Cu).

[0013] The solid electrolyte layer is a layer containing a solid electrolyte such as a sulfide solid electrolyte or an oxide solid electrolyte as a main component. The solid electrolyte layer is formed by mixing a solid electrolyte layer (95 wt%) and a binder (5 wt%) at the above mixing ratio, applying the mixture, and drying it.

[0014] The positive electrode layer is, for example, a layer containing a positive electrode active material containing sulfur, which releases lithium ions during charging and occludes lithium ions during discharging. The positive electrode layer is formed, for example, by preparing a mixture of a positive electrode active material (NMC) (84 wt%) mainly composed of nickel, manganese, and cobalt, a solid electrolyte (11 wt%), a conductive auxiliary agent (3 wt%), and a binder (2 wt%) at the above mixing ratio, applying the mixture, drying it, and then pressing it.

[0015] The negative electrode layer can be a layer of a negative electrode active material containing at least lithium metal or a lithium alloy, or a thin plate such as stainless steel. The negative electrode layer occludes lithium ions during charging and releases lithium ions during discharging.

[0016] Incidentally, when the load (charge and discharge) on the battery cell 1 increases, the temperature of the battery cell 1 rises. When the temperature exceeds a predetermined temperature (for example, a temperature corresponding to the melting point of lithium (180.5 °C)), the lithium metal softens. If the pressurization on the battery cell 1 continues as it is, the lithium metal precipitated due to softening is extruded by the pressurization and irreversibly moves, for example, to the side surface of the laminate, and further reaches the side surface of the positive electrode layer along the side surface of the solid electrolyte layer, which may cause the battery cell 1 to short-circuit.

[0017] The pressure plates 2 (pressure plates 2A and 2B) are, for example, rectangular aluminum plates with an anodized surface, which are electrically insulated from the battery cell 1 but have good thermal conductivity.

[0018] The connecting portions 3 are arranged between a pair of pressure plates 2 (pressure plates 2A and 2B), and as shown in FIG. 1, a plurality of them are arranged so as to go around the peripheral portion of the pressure plate 2 in a plan view. The cross-sectional shape of the connecting portion 3 is circular as shown in FIG. 1, but other shapes such as an ellipse or a rectangle can also be applied.

[0019] The length of the connecting portion 3 is set to be the thickness of the battery cell 1 when the battery cell 1 is pressed from the thickness direction.

[0020] As a connection form between the connecting portion 3 and the pressing plate 2, for example, as shown on the left side of FIG. 2, a concave portion 21 is formed in the pressing plate 2, the connecting portion 3 is fitted into the concave portion 21, and bolt holes 22 are formed so as to penetrate the connecting portion 3 from a position facing the concave portion 21 on the side surface of the pressing plate 2 and the connecting portion 3. Then, there is a form in which a pair of pressing plates 2 sandwich the battery cell 1 and bolts 23 are screwed into the bolt holes 22 in a state where the battery cell 1 is pressed.

[0021] Also, as shown on the right side of FIG. 2, there is a form in which a pair of pressing plates 2 sandwich the battery cell 1 and the end portion of the connecting portion 3 and the pressing plate 2 are joined by welding or solid-phase bonding in a state where the battery cell 1 is pressed.

[0022] The connecting portion 3 includes a first connecting member 31 connected to the pressing plate 2A, a second connecting member 32 connected to the pressing plate 2B, and a joint portion 33 disposed between the first connecting member 31 and the second connecting member 32 and joining (connecting) the first connecting member 31 and the second connecting member 32.

[0023] For the first connecting member 31 and the second connecting member 32, materials having high thermal conductivity such as copper (Cu) are applied, for example.

[0024] The joint portion 33 is formed of an organic material such as resin, and in addition to epoxy resin (melting point: 138 - 146 °C (hydroquinone type), 77 - 85 °C (bisphenol type), 116 - 126 °C (thioether type)), low-density polyethylene (melting point: 95 - 130 °C), high-density polyethylene (melting point: 120 - 140 °C), polystyrene (melting point: 120 - 140 °C), acrylonitrile styrene (melting point: 115 °C), ABS resin (melting point: 100 - 125 °C), polycarbonate (melting point: 150 °C), acrylic resin (melting point: 90 - 105 °C), etc. can be applied.

[0025] The heat generated in the battery cell 1 is transmitted to the joint portion 33. As the transmission path, there are a transmission path from the battery cell 1 through the pressure plate 2A and the first connecting member 31 to the joint portion 33, and a transmission path from the battery cell 1 through the pressure plate 2B and the second connecting member 32 to the joint portion 33. Further, the joint portion 33 can be set to melt at a temperature lower than the temperature at which the lithium metal in the battery cell 1 softens by applying the above materials.

[0026] At this time, since the pressure plate 2A, the pressure plate 2B, the first connecting member 31, and the second connecting member 32 are all formed of materials having high thermal conductivity as described above, the temperature difference between the temperature of the battery cell 1 and the joint portion 33 can be set to be small. Therefore, the temperature of the battery cell 1 when the joint portion 33 melts can be set lower than the temperature at which the lithium metal softens.

[0027] In the present embodiment, before the lithium metal in the battery cell 1 softens (or when the degree of softening of the lithium metal is still low), the joint portion 33 melts and the connection via the joint portion 33 between the first connecting member 31 and the second connecting member 32 is released. Thereby, before the lithium metal in the battery cell 1 softens, the pressurized state of the battery cell 1 by the pressure plate 2A and the pressure plate 2B is released, so that the irreversible movement of the lithium metal can be suppressed.

[0028] The connecting portion 3 may be configured to contact the side surface of the battery cell 1. Thereby, since the heat from the battery cell 1 is received through the exterior material of the battery cell 1, the connecting portion 3 (joint portion 33) can be quickly heated.

[0029] The connecting portion 3 may be configured to contact the electrode tab 11. Thereby, since the heat from the battery cell 1 is received through the electrode tab 11 connected to the current collector in the battery cell, the connecting portion 3 (joint portion 33) can be quickly heated. In this case, the electrode tab 11 comes into contact with any one of the first connecting member 31, the second connecting member 32, and the joint portion 33, but the joint portion 33 can be efficiently heated by bringing the electrode tab 11 into contact with the joint portion 33.

[0030] As shown in FIG. 1, the connecting portion 3 includes a connecting portion 3A disposed adjacent to the corner portion of the pressing plate 2, and a connecting portion 3B disposed adjacent to the central portion of the long side and the central portion of the short side of the pressing plate 2. However, it is also preferable to omit the connecting portion 3A and configure to connect the pressing plates 2A and 2B only by the connecting portion 3B. Thereby, since the path from the battery cell 1 to the connecting portion 3 (connecting portion 3B) via the pressing plate 2 can be set short, the sensitivity of the temperature change of the joint portion 33 to the temperature change of the battery cell 1 can be increased.

[0031] In addition, when the thermal conductivity of the pressing plate 2 (pressing plates 2A, 2B) is Σ1 and the thermal conductivity of the connecting portion 3 is Σ2, it is preferable to satisfy the relationship of Σ2>Σ1. Thereby, since the heat transmitted from the battery cell 1 to the pressing plate 2 (pressing plates 2A, 2B) is easily transmitted to the connecting portion 3, the joint portion 33 can be quickly heated and melted.

[0032] [Second Embodiment] FIG. 3 is a plan view of the battery module 100 according to the second embodiment. FIG. 4 is a side view (left side) of the battery module 100 according to the second embodiment and a cross-sectional view taken along line A-A of FIG. 3 (right side).

[0033] As shown in FIG. 3, in the battery module 100 according to the second embodiment, the connecting portion 3 has a thin plate shape in contact with at least two sides including the corner portion on the side surface of the pressing plate 2. As shown in FIG. 3, four connecting portions 3 are prepared and have an L-shaped shape so as to cover the four corners of the rectangular pressing plate 2. At this time, the joint portion 33 constituting the connecting portion 3 also has an L-shaped shape in plan view. Further, the joint portion 33 is disposed, for example, at a position between the pressing plates 2A and 2B in the thickness direction. On the other hand, for example, a configuration in which the first connecting member 31 is connected to the pressing plate 2A, the entire joint portion 33 is connected to the pressing plate 2A, and the second connecting member 32 is connected to the pressing plates 2B and 2A is excluded.

[0034] With the above configuration, the contact areas between the first connecting member 31 and the pressure plate 2A, and between the second connecting member 32 and the pressure plate 2B can be increased. As a result, the efficiency of heat conduction to the first connecting member 31 and the second connecting member 32 is enhanced, and the joint 33 is more easily heated.

[0035] For example, the connecting portion 3 may be formed in a U-shaped configuration in plan view so as to cover two corner portions at both ends of the long side of the pressure plate 2, and may be in contact with one of the short sides (side surfaces), one of the long sides (side surfaces), and the other of the short sides (side surfaces) of the pressure plate 2 simultaneously.

[0036] Also, as shown in FIG. 3, a configuration in which the first connecting member 31 extends to the upper surface of the pressure plate 2A and the second connecting member 32 extends to the lower surface of the pressure plate 2B can also be applied.

[0037] Then, a countersink 24A having a depth substantially the same as the thickness of the first connecting member 31 is formed at a corner portion of the upper surface of the pressure plate 2A, and a countersink 24B having a depth substantially the same as the thickness of the second connecting member 32 is formed at a corner portion of the lower surface of the pressure plate 2B. A portion of the first connecting member 31 that extends to the upper surface of the pressure plate 2A is disposed in the countersink 24A, and a portion of the second connecting member 32 that extends to the lower surface of the pressure plate 2B is disposed in the countersink 24B. This configuration is preferable.

[0038] As a result, the first connecting member 31 does not protrude in the thickness direction from the pressure plate 2A, and the second connecting member 32 also does not protrude in the thickness direction from the pressure plate 2B. Therefore, when the battery modules 100 of the second embodiment are stacked in the thickness direction (see FIGS. 11 and 12), no gap is formed between the battery modules 100, and thus the stacked structure can be stabilized.

[0039] Even when the countersinks 24A and 24B are not formed, the first connecting member 31 contacts one of the short sides (side surfaces) of the pressure plate 2A, one of the long sides (side surfaces) of the pressure plate 2A, or the upper surface of the pressure plate 2A, and the second connecting member 32 contacts one of the short sides (side surfaces) of the pressure plate 2B, one of the long sides (side surfaces) of the pressure plate 2B, or the upper surface of the pressure plate 2B. Therefore, the efficiency of heat conduction to the first connecting member 31 and the second connecting member 32 is further enhanced, and the joint portion 33 is more easily heated.

[0040] [Third Embodiment] FIG. 5 is a plan view of the battery module 100 according to the third embodiment. FIG. 6 is a cross-sectional view taken along line A-A in FIG. 5. In FIG. 5 (similarly for FIG. 7 described later), the illustration of the upper pressure plate 2A shown in FIG. 6 is omitted.

[0041] In the battery module 100 according to the third embodiment, the electrode tabs 11 (positive electrode tab, negative electrode tab) extending from the battery cell 1 penetrate (contact) at least one joint portion 33. The two electrode tabs 11 extend in opposite directions from the short sides (side surfaces) facing each other in the battery cell 1.

[0042] That is, the electrode tabs 11 (positive electrode tab, negative electrode tab) are arranged so as to pass between the first connecting member 31 and the second connecting member 32. The electrode tab 11, the first connecting member 31, and the second connecting member 32 are set such that, as shown in FIG. 5, the first connecting member 31 and the second connecting member 32 are inside the outer shape of the electrode tab 11 in a plan view.

[0043] The joint portion 33 is divided into a first joint portion 331 that joins the first connecting member 31 and the electrode tab 11 between the lower end portion of the first connecting member 31 facing the upper surface of the electrode tab 11 and the position facing the lower end portion on the upper surface of the electrode tab 11, and a second joint portion 332 that joins the second connecting member 32 and the electrode tab 11 between the upper end portion of the second connecting member 32 facing the lower surface of the electrode tab 11 and the position facing the upper end portion on the lower surface of the electrode tab 11.

[0044] In the third embodiment, as heat transfer paths from the battery cell 1 to the joint portion 33 (the first joint portion 331 and the second joint portion 332) through which the electrode tab 11 is inserted, there are a transfer path (1) from the battery cell 1 to the first joint portion 331 via the pressure plate 2A and the first connecting member 31, a transfer path (2) from the battery cell 1 to the second joint portion 332 via the pressure plate 2B and the second connecting member 32, and a transfer path (3) from the battery cell 1 to the first joint portion 331 and the second joint portion 332 via the electrode tab 11. However, the transfer path (3) can transfer heat faster than the transfer paths (1) and (2). Therefore, the joint portion 33 (the first joint portion 331 and the second joint portion 332) can be heated (melted) quickly accordingly.

[0045] FIG. 7 is a plan view of the battery module 100 according to a modified example of the third embodiment. FIG. 8 is a cross-sectional view taken along line A-A of FIG. 7. In the modified example of the third embodiment, the electrode tabs 11 (positive electrode tab, negative electrode tab) are arranged so as to penetrate (contact) all of the joint portions 33 of the plurality of connecting portions 3.

[0046] As a result, the joint portions 33 (the first joint portion 331 and the second joint portion 332) of the connecting portion 3 all receive heat from the battery cell 1 via the transfer path (3), that is, the electrode tab 11. Therefore, the joint portion 33 can be quickly heated and melted, and the pressurized state with respect to the battery cell 1 can be quickly released.

[0047] [Fourth Embodiment] FIG. 9 is a cross-sectional view of the battery module 100 according to the fourth embodiment. In the battery module 100 according to the fourth embodiment, the connecting portion 3 is not divided into two as in the first to third embodiments. A joint portion 41 is arranged at the connection position between the connecting portion 3 and the pressure plate 2, and the connection state between the connecting portion 3 and the pressure plate 2 is released when the joint portion 41 is melted by heat from the battery cell 1. Note that the same material as that of the joint portion 33 is applied to the joint portion 41.

[0048] In FIG. 9, as the heat transfer path from the battery cell 1 to the joint portion 41, there are a transfer path (4) from the battery cell 1 to the joint portion 41 via the pressure plate 2A and a transfer path (5) from the battery cell 1 to the joint portion 41 via the pressure plate 2B and the connecting portion 3. However, the transfer path (4) can transfer heat faster than the transfer path (5). Also, the transfer path (4) can transfer heat faster than the transfer paths in the first to third embodiments. Therefore, accordingly, the joint portion 41 can be quickly heated and melted, and the pressurized state on the battery cell 1 can be quickly released.

[0049] In FIG. 9, the joint portion 41 is arranged between the upper end portion of the connecting portion 3 and the lower surface of the pressure plate 2A. However, a configuration in which the joint portion 41 is arranged between the lower end portion of the connecting portion 3 and the upper surface of the pressure plate 2B may also be used, and furthermore, both configurations may be implemented simultaneously.

[0050] FIG. 10 is a cross-sectional view of a battery module 100 according to a modified example of the fourth embodiment. In the battery module 100 according to the modified example of the fourth embodiment, a bolt 34 is applied as the connecting portion 3, a female screw into which the bolt 34 is screwed is formed on the pressure plate 2A, and a bolt hole 25 through which the bolt 34 is inserted is formed on the pressure plate 2B. And the region including the female screw of the pressure plate 2A becomes a melting portion 42 that melts due to the heat from the battery cell 1. In the modified example of the fourth embodiment, by tightening the bolt, the pressure plates 2A and 2B are brought closer to each other in the thickness direction to pressurize the battery cell 1.

[0051] The melting portion 42 can be made of the same material as the joint portion 33 in the first to third embodiments and the joint portion 41 in the fourth embodiment. However, as long as it is configured to be screwed with the bolt 34, it does not need to be joined to the bolt 34. When the melting portion 42 melts, the screwing between the melting portion 42 and the bolt 34 is released, the connection state between the bolt 34 and the pressure plate 2A is also released, and the pressurized state on the battery cell 1 is released.

[0052] The joint portion 41 (FIG. 9) in the fourth embodiment and the melting portion 42 (FIG. 10) in its modified example are heated by directly receiving heat from the pressure plate 2A, and thus can be quickly heated and melted accordingly.

[0053] [Fifth Embodiment] FIG. 11 is a cross-sectional view of the battery module 100 according to the fifth embodiment. The battery module 1000 according to the fifth embodiment has a stacked structure in which, for example, a plurality of the battery modules 100 according to any one of the first to fourth embodiments are stacked in the thickness direction.

[0054] In FIG. 11, a battery module 100 substantially the same as that of the first embodiment is applied, but the structures of the pressure plates 2A and 2B are different. That is, the pressure plate 2A has a stacked structure of a first layer 26 and a second layer 27. The lower surface of the first layer 26 is connected to the connecting portion 3, and the second layer 27 is stacked on the first layer 26.

[0055] The pressure plate 2B has a stacked structure of a first layer 26 and a second layer 27 similar to the pressure plate 2A. The second layer 27 is stacked on the first layer 26, and the connecting portion 3 is connected to the upper surface of the second layer 27.

[0056] The first layer 26 is formed of an aluminum plate similar to that of the first embodiment, and for the second layer 27, a material having a lower thermal conductivity than the first layer 26, such as mica, can be applied.

[0057] In the above configuration, in each battery module 100, there is a heat transfer path from the battery cell 1 to the joint portion 33 via the pressure plate 2A and the first connecting member 31, but the heat transfer path via the pressure plate 2B and the second connecting member 32 is restricted by the second layer 27.

[0058] Therefore, when applying the battery module 100 (FIGS. 9 and 10) of the fourth embodiment to the fifth embodiment, the joint portion 41 is arranged at a position in contact with the first layer 26.

[0059] Here, when the thermal conductivity of the first layer 26 is Σ1 and the thermal conductivity of the connecting portion 3 is Σ2, it is preferable to satisfy the relationship Σ2>Σ1. Thereby, the heat transferred from the battery cell 1 to the pressure plate 2A (first layer 26) is easily transferred to the connecting portion 3, so that the joint portion 33 can be quickly heated and melted.

[0060] In the fifth embodiment, regarding the heat generated in the battery cell 1 of the specific battery module 100, the heat propagation in the thickness direction of the specific battery module 100 is restricted by the second layer 27 of the pressure plate 2A of the specific battery module 100 and the second layer 27 of the pressure plate 2B of the specific battery module 100. Therefore, when a stacked structure as in the fifth embodiment is formed, even if the battery cell 1 of the specific battery module 100 reaches a high temperature such that the lithium metal melts, the heat transfer to the battery cell 1 of other battery modules 100 is restricted, and thermal runaway spreading over the entire stacked structure can be suppressed.

[0061] FIG. 12 is a cross-sectional view of a battery module 1000 according to a modified example of the fifth embodiment. In the battery module 1000 according to the modified example of the fifth embodiment, the pressure plate 2A and the pressure plate 2B have a three-layer structure.

[0062] The pressure plate 2A and the pressure plate 2B have a stacked structure in which the second layer 27 is stacked on the first layer 26, and the third layer 28 (for example, the same material as the first layer 26) is stacked on the second layer 27.

[0063] In this case, in each battery module 100, the heat transfer path from the battery cell 1 to the joint 33 in each battery module 100 includes a transfer path that reaches the joint 33 via the pressure plate 2A and the first connecting member 31, and a transfer path that reaches the joint 33 via the pressure plate 2B and the second connecting member 32.

[0064] In the modified example of the fifth embodiment, regarding the heat generated in the battery cell 1 of the specific battery module 100, the heat propagation in the thickness direction of the specific battery module 100 is restricted by the second layer 27 of the pressure plate 2A of the specific battery module 100 and the second layer 27 of the pressure plate 2B of the specific battery module 100. Therefore, when a stacked structure as in the fifth embodiment is formed, even if the battery cell 1 of the specific battery module 100 reaches a high temperature such that the lithium metal melts, the heat transfer to the battery cell 1 of other battery modules 100 is restricted, and thermal runaway spreading over the entire stacked structure can be suppressed.

[0065] [Effects of the Present Embodiment] The battery module 100 of the present embodiment includes a battery cell 1, a pair of pressure plates 2 (pressure plate 2A, pressure plate 2B) that sandwich the battery cell 1 in the thickness direction to press the battery cell 1, and a connecting portion 3 that connects the pair of pressure plates 2 in a state where the pair of pressure plates 2 press the battery cell 1. The connecting portion 3 includes a first connecting member 31 connected to one of the pair of pressure plates 2 (pressure plate 2A), a second connecting member 32 connected to the other of the pair of pressure plates 2 (pressure plate 2B), and a joining portion 33 disposed between the first connecting member 31 and the second connecting member 32 to join the first connecting member 31 and the second connecting member 32. The joining portion 33 is heated by heat transmitted from the battery cell 1 through one of the pressure plates 2 (pressure plate 2A) and the first connecting member 31, or heat transmitted from the battery cell 1 through the other of the pressure plates 2 (pressure plate 2B) and the second connecting member 32. Further, when the temperature of the joining portion 33 exceeds a predetermined temperature (the melting point of the material constituting the joining portion 33), it melts and releases the joining of the first connecting member 31 and the second connecting member 32.

[0066] With the above configuration, when the battery cell 1 becomes high temperature, the lithium metal in the battery cell 1 softens. In this case, the joining portion 33 melts due to the heat transmitted from the battery cell 1, and the joining of the first connecting member 31 and the second connecting member 32 is released, thereby releasing the pressure on the battery cell 1. Therefore, irreversible movement of the lithium metal in the battery cell 1 can be suppressed.

[0067] In the present embodiment, the pressure plate 2 has a rectangular shape, and the connecting portion 3 is in contact with at least two sides including a corner portion on a side surface of the pressure plate 2.

[0068] With the above configuration, the contact area between the connecting portion 3 and the pressure plate 2 increases, so the heat transfer efficiency from the pressure plate 2 to the connecting portion 3 is increased, and the joining portion 33 constituting the connecting portion 3 can be efficiently heated.

[0069] In the present embodiment, the pressure plate 2 has a rectangular shape, and the connecting portion 3 (connecting portion 3B) is disposed adjacent to the center of the long side of the pressure plate 2 and / or the center of the short side of the pressure plate 2 at the peripheral portion of the pressure plate 2 in a plan view.

[0070] With the above configuration, the path from the battery cell 1 to the connecting portion 3 (connecting portion 3B) via the pressing plate 2 can be set short, so that the sensitivity of the temperature change of the joint portion 33 to the temperature change of the battery cell 1 can be increased.

[0071] In the present embodiment, the battery cell 1 includes an electrode tab 11 (negative electrode tab, positive electrode tab) that extends from the side surface of the battery cell 1 and is electrically connected to an internal electrode (negative electrode current collector, positive electrode current collector) disposed in the battery cell 1, and the connecting portion 3 is in contact with the electrode tab 11.

[0072] With the above configuration, since the connecting portion 3 receives the heat of the battery cell 1 through the electrode tab 11, the heat generated in the battery cell 1 can be quickly transmitted to the joint portion 33 that constitutes the connecting portion 3, and the joint portion 33 can be quickly heated.

[0073] In the present embodiment, the electrode tab 11 passes between the first connecting member 31 and the second connecting member 32, and the joint portion 33 includes a first joint portion 331 disposed between the first connecting member 31 and the electrode tab 11 and joining the first connecting member 31 and the electrode tab 11, and a second joint portion 332 disposed between the second connecting member 32 and the electrode tab 11 and joining between the second connecting member 32 and the electrode tab 11.

[0074] With the above configuration, since the electrode tab 11 is supported by the connecting portion 3, the contact state between the electrode tab 11 and the connecting portion 3 can be kept good. Also, since the electrode tab 11 directly heats the joint portion 33 (first joint portion 331, second joint portion 332), the joint portion 33 (first joint portion 331, second joint portion 332) can be heated more efficiently than when the joint portion 33 is heated via the first connecting member 31 or the second connecting member 32.

[0075] Further, the battery module 100 of the present embodiment includes a battery cell 1, a pair of pressing plates 2 (pressing plate 2A, pressing plate 2B) that sandwich the battery cell 1 from the thickness direction to press the battery cell 1, a connecting portion 3 that connects the pair of pressing plates 2 in a state where the pair of pressing plates 2 press the battery cell 1, and a joining portion 41 that is disposed at at least one of a pair of connection positions that are connection positions between the pressing plate 2 and the connecting portion 3 and are both ends of the connecting portion 3 in the thickness direction of the battery cell 1, and joins the pressing plate 2 (pressing plate 2A) and the connecting portion 3 to each other. The joining portion 41 is heated by the heat transmitted from the battery cell 1 through the pressing plate 2 (pressing plate 2A), and when the temperature of the joining portion 41 exceeds a predetermined temperature (the melting point of the material constituting the joining portion 41), it melts and releases the joining between the pressing plate 2 (pressing plate 2A) and the connecting portion 3.

[0076] With the above configuration, when the battery cell 1 becomes high temperature, the lithium metal in the battery cell 1 softens. In this case, the joining portion 41 melts due to the heat transmitted from the battery cell 1, and the joining between the pressing plate 2 (pressing plate 2A) and the connecting portion 3 is released, so that the pressure on the battery cell 1 is released. Therefore, irreversible movement of the lithium metal in the battery cell 1 can be suppressed.

[0077] In the present embodiment, when a plurality of integrated bodies (battery modules 100) of the battery cell 1, the pressing plate 2, and the connecting portion 3 are stacked in the thickness direction of the battery cell to form a stacked structure (battery module 1000), the pressing plate 2 includes a first layer 26 and a second layer 27 stacked on the first layer 26. The second layer 27 is set to have a lower thermal conductivity than the first layer 26. In the integrated body (battery module 100), the first layer 26 of either one of the pair of pressing plates 2 (for example, pressing plate 2A) is disposed so as to contact the battery cell 1.

[0078] With the above configuration, the heat transfer path from the battery cell 1 to the joint portion 33 has, for example, a path that reaches the joint portion 33 via the first layer 26 of the pressure plate 2A and the first connecting member 31 from the battery cell 1, and the joint portion 33 can be heated by the heat of the battery cell 1. Further, with respect to the heat generated in the battery cell 1 of a specific battery module 100, the heat propagation in the thickness direction of the specific battery module 100 is restricted by the second layer 27 of the pressure plate 2A of the specific battery module 100 and the second layer 27 of the pressure plate 2B of the specific battery module 100. Therefore, when a stacked structure as in the fifth embodiment is formed, even if the battery cell 1 of a specific battery module 100 reaches a high temperature such that the lithium metal melts, the heat transfer to the battery cell 1 of other battery modules 100 is restricted, and thermal runaway spreading over the entire stacked structure can be suppressed.

[0079] In the present embodiment, when a plurality of integrated bodies (battery modules 100) of the battery cell 1, the pressure plate 2, and the connecting portion 3 are stacked in the thickness direction of the battery cell 1 (battery module 1000), the pressure plate 2 includes a first layer 26, a second layer 27 stacked on the first layer 26, and a third layer 28 stacked on the second layer 27. In the integrated body (battery module 100), one of the pair of pressure plates 2 (pressure plate 2A) is arranged such that the first layer 26 contacts the battery cell 1, the other of the pair of pressure plates 2 (pressure plate 2B) is arranged such that the third layer 28 contacts the battery cell 1, and the second layer 27 is set to have a lower thermal conductivity than the first layer 26 and the third layer 28.

[0080] With the above configuration, the heat transfer path from the battery cell 1 to the joint 33 has a path from the battery cell 1 to the joint 33 via the first layer 26 of the pressure plate 2A and the first connecting member 31, and a path from the battery cell 1 to the joint 33 via the third layer 28 of the pressure plate 2B and the second connecting member 32. The joint 33 can be heated by the heat of the battery cell 1. Also, regarding the heat generated in the battery cell 1 of a specific battery module 100, the heat propagation in the thickness direction of the specific battery module 100 is restricted by the second layer 27 of the pressure plate 2A of the specific battery module 100 and the second layer 27 of the pressure plate 2B of the specific battery module 100. Therefore, when a stacked structure like the fifth embodiment is formed, even if the battery cell 1 of a specific battery module 100 reaches a temperature high enough to melt the lithium metal, the heat transfer to the battery cell 1 of other battery modules 100 is restricted, and thermal runaway spreading over the entire stacked structure can be suppressed.

[0081] In the present embodiment, when the thermal conductivity of the first layer 26 is Σ1 and the thermal conductivity of the connecting portion 3 is Σ2, the relationship Σ2 > Σ1 is satisfied.

[0082] With the above configuration, the heat transferred from the battery cell 1 to the pressure plate 2A (first layer 26) is more likely to be transferred to the connecting portion 3, so that the joint 33 can be quickly heated and melted.

[0083] As described above, the embodiments of the present invention have been described. However, the configurations described in the above embodiments and each modification example only show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention.

Explanation of Reference Numerals

[0084] 1 Battery cell, 2 Pressure plate, 3 Connecting portion, 31 First connecting member, 32 Second connecting member, 33 Joint, 100 Battery module

Claims

1. A battery cell, A pair of pressure plates that sandwich the battery cell in the thickness direction to pressurize the battery cell, A connecting portion that connects the pair of pressure plates in a state where the pair of pressure plates pressurize the battery cell, and includes: The connecting portion includes: A first connecting member connected to one of the pair of pressure plates, A second connecting member connected to the other of the pair of pressure plates, A joining portion disposed between the first connecting member and the second connecting member to join the first connecting member and the second connecting member, and includes: The joining portion: A battery module that is heated by heat transmitted from the battery cell through one of the pressure plates and the first connecting member, or heat transmitted from the battery cell through the other of the pressure plates and the second connecting member, and further melts when the temperature of the joining portion exceeds a predetermined temperature to release the joining between the first connecting member and the second connecting member.

2. The pressure plate has a rectangular shape, The battery module according to claim 1, wherein the connecting portion is in contact with at least two sides including corners on a side surface of the pressure plate.

3. The pressure plate has a rectangular shape, The battery module according to claim 1, wherein the connecting portion is disposed adjacent to the center of the long side of the pressure plate and / or the center of the short side of the pressure plate at the peripheral portion of the pressure plate in a plan view.

4. The battery cell includes an electrode tab that extends from a side surface of the battery cell and is electrically connected to an internal electrode disposed in the battery cell, The battery module according to claim 1, wherein the connecting portion is in contact with the electrode tab.

5. The electrode tab passes between the first connecting member and the second connecting member, The battery module according to claim 4, wherein the joining portion includes a first joining portion disposed between the first connecting member and the electrode tab to join the first connecting member and the electrode tab, and a second joining portion disposed between the second connecting member and the electrode tab to join the second connecting member and the electrode tab.

6. A battery cell, A pair of pressure plates that sandwich the battery cell in the thickness direction to pressurize the battery cell, A connecting portion that connects the pair of pressure plates in a state where the pair of pressure plates pressurize the battery cell, A joint portion that is disposed at a connection position between the pressing plate and the connecting portion and that is at both ends in the thickness direction of the battery cell of the connecting portion, and that joins the pressing plate and the connecting portion to each other. The joint portion is heated by heat transmitted from the battery cell through the pressing plate, and when the temperature of the joint portion exceeds a predetermined temperature, it melts to release the joint between the pressing plate and the connecting portion. A battery module. **Claim 7** In the case where a plurality of integrated bodies of the battery cell, the pressing plate, and the connecting portion are stacked in the thickness direction of the battery cell to form a stacked structure. The pressing plate includes a first layer and a second layer stacked on the first layer. The second layer is set to have a lower thermal conductivity than the first layer. The battery module according to any one of claims 1 to 6, wherein in the integrated body, the first layer of either one of the pair of pressing plates is disposed so as to contact the battery cell. **Claim 8** In the case where a plurality of integrated bodies of the battery cell, the pressing plate, and the connecting portion are stacked in the thickness direction of the battery cell. The pressing plate includes a first layer, a second layer stacked on the first layer, and a third layer stacked on the second layer. In the integrated body, one of the pair of pressing plates is disposed such that the first layer contacts the battery cell, and the other of the pair of pressing plates is disposed such that the third layer contacts the battery cell. The battery module according to any one of claims 1 to 6, wherein the second layer is set to have a lower thermal conductivity than the first layer and the third layer. **Claim 9** The battery module according to claim 7, wherein when the thermal conductivity of the first layer is Σ1 and the thermal conductivity of the connecting portion is Σ2, the relationship Σ2 > Σ1 is satisfied.

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