Secondary batteries and battery modules

Abstract

To provide a secondary battery with improved cooling and heating efficiency.SOLUTION: A secondary battery includes a laminate including a positive electrode layer, an electrolyte layer, and a negative electrode layer, and an exterior body that wraps the laminate, and the exterior body is formed by folding back a piece of material forming the exterior body at a folding portion, the exterior body including a housing portion that includes the folding portion as a part thereof and houses the laminate, and a peripheral edge portion around the housing portion. The peripheral edge portion includes a folding portion folded along the housing portion, and in the folding portion, the materials are not joined to each other on a bent portion, and the materials are joined to each other at a portion other than the bent portion.SELECTED DRAWING: Figure 8

Description

Technical Field

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

Background Art

[0002] From the perspective of climate-related disasters, in order to reduce CO2, the electrification of industrial machines has been promoted, and research on secondary batteries has also been advanced for applications such as vehicles as an energy source. In such a secondary battery group (battery module) composed of secondary batteries (batteries), since the performance or life of the battery may be affected by temperature, a structure for adjusting the temperature of the battery may be provided. Patent Document 1 describes a battery module provided with a heat conductive material that is integrally in contact with a battery and a cooling plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In cooling and heating the battery, it is desirable to efficiently transfer the heat of the battery or the heat to the battery. However, depending on the contact condition between the battery and the heat conductive material or the like, the efficiency of cooling and heating may decrease, and there is room for improvement in the cooling and heating structure.

[0005] An object of the present invention is to provide a secondary battery with improved cooling and heating efficiency. And it contributes to the improvement of energy efficiency.

Means for Solving the Problems

[0006] According to the present invention, a laminate in which a positive electrode layer, an electrolyte layer, and a negative electrode layer are laminated, and The laminate comprises an outer casing that encloses the laminate, The exterior body is formed by folding a single material that forms the exterior body at the folded portion, The exterior body includes the folded portion as part thereof, a housing portion that houses the laminate, and a peripheral portion around the housing portion. The aforementioned peripheral portion includes a folding portion that is folded along the aforementioned housing portion, In the aforementioned folding portion, the materials are not joined together on the bent portion, but are joined together in areas other than the bent portion. Occasionally, The folding portion includes a first region extending from the connection portion with the housing portion to one side in the stacking direction of the laminate, and a second region extending from the one end of the first region to the other side opposite to the one side, wherein a highly viscous fluid is applied between the opposing surfaces of the material in the first region and the second region. A rechargeable battery is provided. [Effects of the Invention]

[0007] According to the present invention, the efficiency of cooling and heating secondary batteries can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic cross-sectional view showing a battery module according to one embodiment. [Figure 2] A front view of a secondary battery according to one embodiment. [Figure 3] A cross-sectional view of a secondary battery according to one embodiment, shown along line AA. [Figure 4] A plan view showing the composition of the materials forming the exterior body according to one embodiment. [Figure 5] View from arrow C in Figure 4. [Figure 6] A schematic diagram showing the overlapping of materials forming an exterior body according to one embodiment. [Figure 7] A front view of a secondary battery according to one embodiment, showing the state before the upper and lower parts of the sealed outer casing are folded. [Figure 8] Figure 2 is a cross-sectional view along line BB, showing the folding structure of an exterior body according to one embodiment. [Figure 9] A front view of a secondary battery according to another embodiment, showing the state before the upper and lower parts of the sealed casing are folded. [Figure 10] A diagram showing a bending structure of an exterior body according to another embodiment. [Figure 11] A diagram showing a bending structure of an exterior body according to yet another embodiment. [Figure 12] A plan view showing the configuration of a material forming an exterior body according to another embodiment. [Figure 13] View C of FIG. 12. [Figure 14] A diagram showing the material forming an exterior body according to another embodiment folded. [Figure 15] A front view of a secondary battery according to another embodiment, showing a state before the upper part of the sealed exterior body is folded.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are given the same reference numerals, and duplicate explanations are omitted.

[0010] <Secondary Battery According to an Embodiment> A secondary battery according to an embodiment includes a laminate in which a positive electrode layer, an electrolyte layer, and a negative electrode layer are laminated, and an exterior body that wraps the laminate. The exterior body is formed by overlapping two materials forming the exterior body, and includes a housing portion that houses the laminate and a peripheral portion around the housing portion. Further, the peripheral portion includes a folded portion folded along the housing portion, and the materials are not joined to each other on the bent portion where the folded portion is bent, and the materials are joined to each other outside the bent portion. Thereby, the efficiency of cooling and heating of the secondary battery can be improved. First, a battery module BM including a secondary battery according to an embodiment will be described, and details of the secondary battery will be described later.

[0011] (Battery Module BM) FIG. 1 is a cross-sectional view schematically showing a battery module according to an embodiment. The battery module 100 can be mounted on an electric vehicle such as a hybrid vehicle or an EV (not shown). The battery module 100 includes a plurality of secondary batteries 200, a plurality of separators 300, a cooling / heating means 410, and a plurality of first heat transfer members 420. Further, the battery module 100 can also include a plurality of second heat transfer members 430.

[0012] The plurality of secondary batteries (batteries) 200 are stacked in their thickness direction (Z direction) to form a secondary battery group. The secondary batteries 200 are stacked alternately with the insulating separators 300 in the Z direction in a standing posture. At both ends of the laminate of the secondary batteries 200 and the separators 300 in the stacking direction, substantially flat end plates 500 are arranged. The end plates 500 are formed with holes through which fastening bolts 510 for fixing the battery module 100 to the installation site 600 can pass. The installation site 600 is formed, for example, by the sheet metal of an electric vehicle, and a pair of female screw portions 610 into which a pair of fastening bolts 510 are screwed are formed.

[0013] The cooling / heating means 410 cools or heats the secondary batteries 200. In this embodiment, the cooling / heating means 410 is a heat sink through which a refrigerant or a heat medium passes through a fluid passage 412 formed in a plate-like member 411. However, the cooling / heating means 410 may be, for example, an air-cooled cooling structure that introduces the running wind during vehicle travel, or other known techniques can be appropriately used.

[0014] (First Heat Transfer Member) The first heat transfer member 420 transfers heat from the secondary battery 200, or heat to the secondary battery 200, to or from the cooling / heating means 410. The first heat transfer member 420 is positioned between the secondary battery 200 and the cooling / heating means 410. A heat-conducting gel such as silicone gel may be used as the first heat transfer member 420. Alternatively, for example, the first heat transfer member 420 could be a urethane-based, epoxy-based, modified silane-based, or acrylic-based heat dissipation adhesive, a clay-like silicone putty sheet for heat dissipation that adheres well to uneven surfaces, or a silicone grease for heat dissipation.

[0015] (Second heat transfer component) The second heat transfer member 430 transfers heat from the secondary battery 200, or heat to the secondary battery 200, upward, or from the upward. Hereinafter, the side of the secondary battery 200 with the cooling / heating means 410 may be referred to as the downward side, and the side opposite the cooling / heating means 410 may be referred to as the upward side. The secondary battery 200 is fixed by a fixing member (not shown), for example, a case or a binding bar, and the heat of the secondary battery 200 can be configured to be transferred to the fixing member via the second heat transfer member 430. As a result, the second heat transfer member 430 dissipates heat from the secondary battery 200 upward in addition to downward, thereby improving the cooling efficiency of the secondary battery 200.

[0016] The second heat transfer member 430 may be made of a heat-conducting gel such as silicone gel, similar to the first heat transfer member 420. For example, the second heat transfer member 430 can be made of a urethane-based, epoxy-based, modified silane-based, or acrylic-based heat-dissipating adhesive, a clay-like silicone putty sheet for heat dissipation that adheres well to uneven surfaces, or a silicone grease for heat dissipation. Alternatively, the second heat transfer member 430 may not be provided on the secondary battery 200, and the heat from the secondary battery 200 can be directly dissipated to the fixing member or the space above the secondary battery 200.

[0017] (Secondary battery) Figure 2 is a front view of a secondary battery according to one embodiment, and Figure 3 is a cross-sectional view of the secondary battery according to one embodiment, taken along line AA. In the figures, arrow X indicates the longitudinal direction of the secondary battery 200 (or the direction in which the lead terminals extend), arrow Y indicates the width direction of the secondary battery 200 (or the direction perpendicular to the direction in which the lead terminals extend), and arrow Z indicates the thickness direction of the secondary battery 200 (the stacking direction of the laminate 210). The X, Y, and Z directions are perpendicular to each other. Figure 2 is a view of the secondary battery 200 in the Z direction, and is also a view of the stacking direction of the laminate of the secondary battery 200 and separator 300 shown in Figure 1.

[0018] The secondary battery 200 includes a laminate 210 which is an element of the secondary battery, lead terminals 221 and 222, current collector terminals 223 and 224, and an outer casing 230 which encloses the laminate 210, and has a battery cell configuration suitable for a battery pack.

[0019] The laminate 210 has a rectangular parallelepiped shape as a whole, and as shown in Figure 3, it has a two-layer structure of positive and negative electrode layers, including two positive electrode layers 211 and 212 and two negative electrode layers 213 and 214. However, the laminate 210 may have one positive electrode layer or three or more layers. An electrolyte layer 219 is provided between the positive electrode layer 211 and the negative electrode layer 213, and between the positive electrode layer 212 and the negative electrode layer 214.

[0020] Each of the positive electrode layers 211 and 212 includes a positive electrode active material layer 215, and both positive electrode layers 211 and 212 have a common positive electrode current collector 216. The positive electrode current collector 216 is arranged in layers in the center of the laminate 210 in the Z direction, with each positive electrode active material layer 215 laminated on its front and back sides.

[0021] The negative electrode layers 213 and 214 are positioned on the outside in one direction in the Z-direction and the outside in the other direction relative to the positive electrode layers 211 and 212, and are stacked such that the negative electrode layers 213 and 214 sandwich the positive electrode layers 211 and 212. However, a configuration in which two positive electrode layers sandwich two negative electrode layers is also possible, the opposite of the configuration in this embodiment. The negative electrode layers 213 and 214 each include a negative electrode active material layer 217 and a negative electrode current collector 218. The two negative electrode current collectors 218 are each formed in layers on the outermost layer of the laminate 210.

[0022] Examples of active materials constituting the positive electrode active material layer 215 include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and metallic lithium phosphate. Examples of active materials constituting the negative electrode active material layer 217 include lithium-based materials and silicon-based materials. Examples of lithium-based materials include Li metal and Li alloy. Examples of silicon-based materials include Si and SiO. In addition to the above, other active materials constituting the negative electrode active material layer 217 include carbon materials such as graphite, soft carbon and hard carbon, tin-based materials (Sn, SnO, etc.), and lithium titanate.

[0023] The electrolyte layer 219 contains, for example, a solid, gel-like, or liquid electrolyte having ionic conductivity. Examples of such materials include sulfide-based solid electrolyte materials, oxide-based solid electrolyte materials, nitride-based solid electrolyte materials, halide-based solid electrolyte materials, and gel-like materials containing lithium-containing salts or lithium-ion conductive ionic liquids. The positive electrode current collector 216 and the negative electrode current collector 218 are made of, for example, metal foil, metal sheet, or metal plate made of aluminum, copper, or SUS. The positive electrode active material layer 215, the negative electrode active material layer 217, and the electrolyte layer 219 may be formed by binding particles of the materials constituting them with an organic polymer compound binder. In one embodiment, the secondary battery 200 may be an all-solid-state battery.

[0024] The lead terminals 221 and 222 are used to charge or discharge the laminate 210 by connecting them to a charger or electrical load. One end of the lead terminals 221 and 222 is located outside the outer casing 230, and the other end is located inside the outer casing 230. Here, the inside of the outer casing 230 refers to the space formed by the sealing portion of the outer casing 230, which will be described later.

[0025] The other end of lead terminal 221 is connected to the positive current collector 216 via current collector terminal 223 inside the casing 230, and lead terminal 221 forms the positive terminal. Lead terminal 221 and current collector terminal 223 are formed of, for example, a conductive metal sheet or metal plate. On the other hand, the other end of lead terminal 222 is connected to the negative current collector 218 via current collector terminal 224 inside the casing 230, and lead terminal 222 forms the negative terminal. Lead terminal 222 and current collector terminal 224 are formed of, for example, a conductive metal sheet or metal plate.

[0026] The arrangement of the lead terminals 221 and 222 is not particularly limited, and the lead terminals 221 and 222 may be arranged at both ends in the longitudinal direction (X direction) of the secondary battery 200, or at one end (upper side) in the width direction (Y direction) of the secondary battery 200. In one embodiment, the lead terminals 221 and 222 are arranged at both ends in the longitudinal direction (X direction) of the secondary battery 200, respectively. In this arrangement, during charging, the current flows in the longitudinal direction of the secondary battery 200, generating heat. However, since the first heat transfer member 420 and the second heat transfer member 430 are arranged along the longitudinal direction of the secondary battery 200, the cooling efficiency of the secondary battery 200 is improved.

[0027] Figure 4 is a plan view showing the configuration of the materials forming the exterior body according to one embodiment, Figure 5 is a view taken along arrow C in Figure 4, and Figure 6 is a schematic diagram showing the materials forming the exterior body according to one embodiment superimposed as indicated by the arrow in Figure 5.

[0028] As shown in Figure 3, the outer casing 230 encloses the laminate 210. In this embodiment, two materials, for example, laminate films 232a and 232b, which form the outer casing 230 as shown in Figure 4, are overlapped as indicated by the arrows in Figure 5 to form the outer casing 230 as shown in Figure 6. The laminate films 232a and 232b each have recesses 232c and 232d, respectively, and the overlapping of the laminate films 232a and 232b forms the housing portion 231.

[0029] The housing section 231 includes rectangular main surfaces 231e and 231f that extend in a plane (XY plane) intersecting the stacking direction (Z direction) of the laminate 210 and are opposite to each other, and side surfaces 231a to 231d that are arranged to connect the main surfaces 231e and 231f (see Figures 2 and 3).

[0030] The laminate films 232a and 232b are formed, for example, by covering the front and back surfaces of a metal layer with a resin layer (insulating layer). The outer casing 230 formed from these laminate films 232a and 232b has flexibility that can follow the expansion and contraction of the laminate 210. This flexibility that can follow the expansion and contraction of the laminate 210 can be obtained by the way the laminate 210 is wrapped, the shape and structure of the outer casing 230, etc.

[0031] Figure 7 is a front view of a secondary battery according to one embodiment, showing the state before the upper and lower parts of the sealed casing are folded. The casing 230 includes, when viewed in the Z direction, a housing portion 231 that houses the stacked body 210 and a peripheral portion 233 around the housing portion 231. The peripheral portion 233 has four sides 233a to 233d when viewed in the Z direction. Here, the housing portion 231 is located in the center of the casing 230 when viewed in the Z direction, but it may be positioned off-center to the left and right and / or up and down.

[0032] The secondary battery is formed by housing a laminate 210, to which lead terminals 221, 222 and current collection terminals 223, 224 are connected, in a recess 232c of one laminate film 232a, and then overlapping the other laminate film 232b as shown in Figures 5 and 6, and joining the materials together by adhesive or welding, etc., so as shown in Figure 7, including the four sides 233a to 233d of the peripheral edge 233 around the housing portion 231.

[0033] In this joint, the edges 233b and 233d of the peripheral portion 233 include sealing portions 234 to 235 which are joined together. Also, as shown in Figures 2 and 3, the peripheral portion including sealing portions 234 to 235 extends from the sides 231b and 231d of the housing portion 231 in a direction substantially perpendicular to the sides 231b and 231d (X direction).

[0034] Furthermore, in this joining, the peripheral portion 233 that connects to the sides 231a and 231c of the housing portion 231 has sealing portions 236a to 236c and 237a to 237c that are joined discontinuously toward sides 233a and 233c, respectively. The sealing portions 236a to 236c and 237a to 237c are substantially rectangular in shape, extending in the length direction (X direction) and the width direction (Y direction) of the secondary battery 200 when viewed from the stacking direction (Z direction) of the laminate 210.

[0035] Between the sealed portions are unsealed portions where the materials are not joined together. Unsealed portions 238a and 238b are positioned between sealed portions 236a and 236b, and between sealed portions 236b and 236c, respectively. Similarly, unsealed portions 239a and 239b are positioned between sealed portions 237a and 237b, and between sealed portions 237b and 237c, respectively. The unsealed portions 238a, 238b, 239a, and 239b are also roughly rectangular in shape, extending in the longitudinal direction (X direction) and the width direction (Y direction) of the secondary battery 200, similar to the sealed portions.

[0036] The sealed portions 236a to 236c and the unsealed portions 238a and 238b, and the sealed portions 237a to 237c and the unsealed portions 239a and 239b, respectively, correspond to the folded portions P1 and P2 that fold along the housing portion 231. The unsealed portions 238a, 238b, 239a and 239b correspond to the bent portions of the folded portions P1 and P2. In other words, the folded portions P1 and P2 are connected to two rectangular sides of the housing portion 231. Furthermore, as will be described later, the folded portions P1 and P2 extend along the sides 231a and 231c of the housing portion 231 in a direction approximately horizontal (Z direction) to the sides 231a and 231c. Therefore, in Figure 2, the upper and lower surfaces of the outer casing 230 are flat.

[0037] (Folding structure of an exterior body according to one embodiment) Now, as shown in Figure 1, when the secondary battery 200 is used in the battery module 100, the secondary battery 200 is positioned so that a predetermined surface of the secondary battery 200 (the lower surface) is in contact with the first heat transfer member 420. In another embodiment, the secondary battery 200 is positioned so that a second heat transfer member 430 is in contact with another surface of the secondary battery 200 (the upper surface). In yet another embodiment, the first heat transfer member 420 and the second heat transfer member 430 may be configured as one first heat transfer member 420 and one second heat transfer member 430, respectively, so that one first heat transfer member 420 or one second heat transfer member 430 is in contact with multiple secondary batteries 200. In this case, in order to efficiently transfer heat from or to the secondary battery 200, it is desirable to improve the contact between the secondary battery 200 and the first heat transfer member 420 and the second heat transfer member 430. Therefore, in this embodiment, the folded structure of the outer casing 230 described below is adopted.

[0038] Figure 8 is a cross-sectional view of line BB in Figure 2, showing the folded structure of the exterior body according to one embodiment. Figure 8 also shows the structure of the lower part of the secondary battery 200. On the other hand, the upper structure (including the folded structure) of the secondary battery 200 in the cross-sectional view of line BB in Figure 2 is equivalent to the structure inverted from Figure 8, and is therefore omitted. Note that in Figure 8 (and Figures 9 and 10 described later), some parts of the members' thickness and spacing are emphasized to facilitate understanding of the structure.

[0039] In this embodiment, the peripheral portion of the peripheral portion 233 that connects to the sides 231a and 231c of the housing portion 231 (folding portions P1 and P2) is folded along the sides 231a and 231c of the housing portion 231. As described above, the structure of the upper part of the secondary battery 200 is omitted, so the folding portion P2 is not shown in Figure 8.

[0040] The folding portion P1 includes a region R1 extending from the connection portion with the housing portion 231 to one side in the stacking direction (positive Z direction) of the laminate 210, and a region R2 extending from the positive Z-direction end of region R1 to the opposite other side (negative Z direction). In this way, when the folding portion P1 is folded to form multiple regions R1 and R2, the secondary battery 200 and the first heat transfer member 420 can be brought into close contact. As a result, gaps are less likely to occur between the secondary battery 200 and the first heat transfer member 420, so that heat from the secondary battery 200, or heat to the secondary battery 200, can be efficiently transferred to or from the cooling / heating means 410. As a result, the efficiency of cooling and heating the secondary battery 200 is improved.

[0041] Furthermore, the sealed portion of the outer casing is rigid and difficult to bend because the materials of the outer casing are joined together. However, in this embodiment, the folded portion between regions R1 and R2 of the folding portion P1 is not joined together. In other words, the folded portion is formed by a bendable unsealed portion 238a. On the other hand, regions R1 and R2 are formed by sealed portions 236a and 236b, respectively. Hereinafter, the folded portion between regions R1 and R2 may be referred to as the folded portion 238a.

[0042] Region R2 extends from one end (positive side) to the other end (negative side in the Z direction) in the stacking direction (Z direction) of the laminate 2. Therefore, since region R2 extends and is provided over substantially the entire stacking direction below the laminate 210, the contact surface between the secondary battery 200 and the first heat transfer member 420 can be formed by region R2. Consequently, the secondary battery 200 and the first heat transfer member 420 can be brought into close contact.

[0043] Furthermore, the folding portion P1 includes a region R3 that extends in the positive Z direction from the negative Z-direction end of region R2 to the edge (side 233a) of the peripheral portion 233. This stabilizes the height of the folding portion P1 and facilitates close contact between the secondary battery 200 and the first heat transfer member 420.

[0044] Regions R1 and R3 are located closer to the laminate 210 than region R2. Specifically, region R2 is the region where the folded portion P1 is folded downwards (towards the laminate 210) at the bend portion 238a at the positive Z-direction end of region R1. Region R3 is the region where the folded portion P1 is folded upwards (towards the laminate 2) at the bend portion (unsealed portion 238b) on the negative Z-direction side of region R2. Hereinafter, the bend portion between region R2 and region R3 may be referred to as the bend portion 238b. As a result, the folded portion P1 and the heat transfer member 420 only come into contact in region R2, making it less likely for steps or other irregularities to form on these contact surfaces. Therefore, the secondary battery 200 and the first heat transfer member 420 can be brought into close contact.

[0045] In one embodiment, the length L1 (see Figure 7) from the side surface 231a of the housing portion 231 to the edge (side 233a) of the peripheral portion 233 can be approximately twice the length Z1 (see Figure 8) of the laminated body 210 in the stacking direction. In other words, length L1 is approximately twice the length Z1 of the housing portion 231 in the stacking direction. As a result, in the stacking direction (Z direction) of the laminated body 210, the sum of the lengths of regions R1 and R3 is approximately the same as the length of region R2. Therefore, the thickness of the folded portion P1 in the Y direction is made uniform throughout the entire stacking direction (Z direction) of the laminated body 210, making it easier for the secondary battery 200 and the heat transfer member 420 to come into close contact. Approximately twice may represent, for example, 1.95 to 2.05 times, 1.9 to 2.1 times, 1.8 to 2.2 times, or 1.7 to 2.3 times, etc. In other words, the relationship between the sum of the lengths of regions R1 and R3 and the length of region R2 should be such that the secondary battery 200 and the first heat transfer member 420 are in close contact with each other.

[0046] As described in the folding structure of the exterior body according to another embodiment, the length L1 may be longer than the length from the connection point between the folding portion P1 and the housing portion 231 to any end of the housing portion 231 in the Z direction. This allows the folding portion P1 to extend at least to the Z-direction end of the housing portion 231, thereby preventing the folding portion P1 from being interrupted and creating a step where it overlaps with the side surface 321a in the Z direction.

[0047] Next, referring again to Figures 4 to 6, the structures of the laminate films 232a and 232b, which form the exterior body 230, will be described. The laminate films 232a and 232b have an overall sheet-like shape, with recesses 232c and 232d formed therein, respectively.

[0048] Recess 232c is a depression with a depth d1 relative to the sheet-like portion. Recess 232d is a depression with a depth d2 relative to the sheet-like portion. Here, depth d1 = depth d2, but the depths of recess 232c and recess 232d may be different.

[0049] Recesses 232c and 232d are provided such that the distance L1 is greater than or equal to the sum of depths d1 and d2. This allows for a relatively long length of the folding portion P1, making it easier to fold the folding portion P1 along the housing portion 231. Furthermore, because the distance L1 is greater than or equal to the sum of depths d1 and d2, the folding portion P1 can extend in the Z direction from the connection point between the housing portion 231 and the folding portion P1 to the positive or negative end of the housing portion 231 in the Z direction.

[0050] Furthermore, in this embodiment, the recesses 232c and 232d are arranged such that the distance L1 is approximately four times the sum of the depths d1 and d2. This allows the folding portion P1 to be folded to form regions R1 to R3 when forming the outer casing 230 with the laminate films 232a and 232b.

[0051] Furthermore, the peripheral portion of the peripheral portion 233 that connects to the side surface 231c of the housing portion 231 (folding portion P2) also has the same folding structure as the folding portion P1. As a result, as shown in Figure 1, when the secondary battery 200 is used in the battery module 100, the secondary battery 200 and the second heat transfer member 430 can be brought into close contact. Therefore, gaps are less likely to occur between the secondary battery 200 and the second heat transfer member 430, allowing heat from the secondary battery 200, or heat to the secondary battery 200, to be efficiently transferred upwards or from above. Thus, the efficiency of cooling and heating the secondary battery 200 is improved.

[0052] Furthermore, if the peripheral portion 233 is not folded, the first heat transfer member 420 and the second heat transfer member 430 would need to be thickened in the Y direction to absorb the unevenness of the peripheral portion 233. In this embodiment, the folding portions P1 and P2 make the contact surfaces between them and the first heat transfer member 420 and the second heat transfer member 430 flat, so the first heat transfer member 420 and the second heat transfer member 430 can be made thinner in the Y direction. In addition, by making the first heat transfer member 420 and the second heat transfer member 430 thinner, the laminate 210 can be made larger in the Y direction for a secondary battery 200 of the same size, which can also contribute to improving the energy density of the battery module 100.

[0053] Furthermore, when the secondary battery 200 is used in the battery module 100, the folding portions P1 and P2 come into contact with the first heat transfer member 420 and the second heat transfer member 430, so the sides 231a and 231c of the housing portion 231 do not come into direct contact with the first heat transfer member 420 and the second heat transfer member 430. If the sides 231a and 231c of the housing portion 231 come into contact with the first heat transfer member 420 and the second heat transfer member 430, the sides 231a and 231c will expand and contract in accordance with the expansion and contraction of the laminate 210. When the gel-like first heat transfer member 420 and the second heat transfer member 430 are bonded to the sides 231a and 231c, taking heat transfer properties into consideration, the thickness of the first heat transfer member 420 and the second heat transfer member 430 may be ensured so that they stretch in accordance with the expansion of the sides 231a and 231c.

[0054] In this embodiment, the folded portions P1 and P2, which do not follow the expansion and contraction of the laminate 210, come into contact with the first heat transfer member 420 and the second heat transfer member 430. Therefore, it is not necessary to consider the elongation of the gel-like first heat transfer member 420 and the second heat transfer member 430. From this viewpoint as well, in this embodiment, the first heat transfer member 420 and the second heat transfer member 430 can be made thinner in the Y direction.

[0055] (Folding structure of the exterior according to another embodiment) Figure 9 is a front view of a secondary battery according to another embodiment, showing the state before the upper and lower parts of the sealed casing are folded. Figure 10 shows the folding structure of the casing according to another embodiment. Hereafter, the same configuration as the folding structure of the casing according to one embodiment will not be described. Also, the upper structure of the secondary battery 200 (including the folding structure) is equivalent to the structure inverted from Figure 10, so as with Figure 8, it will also be omitted in Figure 10.

[0056] Figure 9 shows the exterior body 230 shown in Figure 10 before it is folded. The exterior body 230 shown in Figure 10 differs from the folding structure of the exterior body 230 of one embodiment mainly in that the folding portion P1 does not include region R3. That is, the folding portion P1 is folded at two places: the connection portion with the housing portion 231 and the bent portion 238b between region R1 and region R2. Even with this configuration, the heat transfer member 420 of the secondary battery 200 and the folding portion P1 can be brought into close contact. Furthermore, region R1 and region R2 are formed by sealing portions 236a and 236b, respectively, and the bent portion between region R1 and region R2 is formed by an unsealed portion 238a.

[0057] (Another embodiment of the folding structure of the exterior body) Figure 11 shows a folding structure of the exterior according to yet another embodiment. Hereafter, the same configuration as the folding structure of the exterior according to one embodiment will not be described. Also, the upper structure of the secondary battery 200 (including the folding structure) is equivalent to the structure shown in Figure 11 when inverted, and therefore, as with Figure 8, it will be omitted in Figure 11 as well.

[0058] The outer casing 230 in Figure 11 differs from the folding structure of the outer casing 230 in one embodiment mainly in that a high-viscosity fluid 440 is applied to the folding portion P1. For example, in the secondary battery 200, the high-viscosity fluid 440 is applied to the folding portion P1 before it is folded (see Figure 7), and then the folding portion P1 is folded. Alternatively, the high-viscosity fluid 440 may be introduced into the folding portion P1 while it is folded.

[0059] The highly viscous fluid 440 is provided in all areas between the side surface 231a of the outer casing 230 and regions R1 and R3, and between regions R1 and R3 and region R2. The highly viscous fluid 440 may also be provided between region R2 and the first heat transfer member 420. However, the arrangement of the highly viscous fluid 440 can be changed as appropriate. For example, since an air layer is unlikely to form between region R2 and the first heat transfer member 420, the highly viscous fluid may not be provided between them, allowing them to be in direct contact.

[0060] In one embodiment of the secondary battery 200, the folded laminate films of the folded portion P1 (for example, regions R1 and R2) are in contact with each other, but strictly speaking, a layer of air exists between them. However, in the folding structure of the outer casing according to yet another embodiment, a highly viscous fluid 440 is applied to the gap in the folded portion P1, improving the adhesion between the laminate films. As a result, heat can be transferred more effectively from the secondary battery 200 to the first heat transfer member 420. Furthermore, the highly viscous fluid 440 may be a thin film. This lowers the thermal resistance and further improves heat transfer.

[0061] Furthermore, as the high-viscosity fluid 440, a grease with thermal conductivity can be used. Examples of such greases include mineral oil or silicone blended with a thermally conductive filler. As the high-viscosity fluid, from the viewpoint of minimizing pump-out, for example, one with an ASTM (JIS) consistency of 1 to 6 can be used.

[0062] (Combination of folding structures for the exterior) Regarding the folding structure of the outer casing, the lower folding part P1 and the upper folding part P2 of the secondary battery 200 may have the same folding structure, or they may have different folding structures. For example, even if both the lower folding part P1 and the upper folding part P2 of the secondary battery 200 have the folding structure shown in Figure 8, the lower folding part P1 of the secondary battery 200 may have the folding structure shown in Figure 8, and the upper folding part P2 of the secondary battery 200 may have the folding structure shown in Figure 9.

[0063] A secondary battery according to another embodiment comprises a laminate formed by stacking a positive electrode layer, an electrolyte layer, and a negative electrode layer, and an outer casing that encloses the laminate. The outer casing is formed by folding a single material that forms the outer casing at a folded portion, and includes a housing portion that houses the laminate, with the folded portion as part of the housing portion, and a peripheral portion around the housing portion. Furthermore, the peripheral portion has a folded portion that is folded along the housing portion, and the materials are not joined together at the bent portion where the folded portion is bent, but are joined together at other points. This improves the cooling efficiency of the battery.

[0064] Another embodiment of the secondary battery differs from the secondary battery 200 of the first embodiment in that its casing is formed by folding a single material at a folded portion. The following description will focus on the casing that differs from the secondary battery 200 of the first embodiment. In addition, in the secondary battery of the other embodiment, the same configuration as the secondary battery of the first embodiment is given a reference number that is one order of magnitude higher. For example, in one embodiment, the secondary battery is denoted as secondary battery 200, and in another embodiment, the secondary battery is denoted as secondary battery 2000.

[0065] Figure 12 is a plan view showing the configuration of the material forming the exterior according to another embodiment, Figure 13 is a view taken along arrow C in Figure 12, and Figure 14 is a diagram showing the material forming the exterior according to one embodiment folded as indicated by the arrow in Figure 13. Figure 15 is a front view of a secondary battery according to another embodiment, showing the state before the upper part of the sealed exterior is folded. In other words, it is a diagram showing the peripheral edge 2330 of the folded material shown in Figure 14 sealed.

[0066] The outer casing 2300 encloses the laminate 2100. In this embodiment, the outer casing 2300 is formed by folding a single piece of material, for example, a single laminate film 2320, in half at the folded portion a. The laminate film 2320 can be made of the same material as the laminate film 232 in one embodiment and has flexibility that can follow the expansion and contraction of the laminate 2100.

[0067] In another embodiment, the outer casing 2300 includes, when viewed in the Z direction, a housing portion 2310 located at the lower center and housing the laminate 2100, and a peripheral portion 2330 around the housing portion 2310. The peripheral portion 2330 has four sides 2330a to 2330d when viewed in the Z direction (see Figure 15).

[0068] As shown in Figures 12 to 14, the housing portion 2310 is formed by overlapping recesses 2320c and 2320d, which are formed on both sides of the folded portion a of the laminate film 2320. The housing portion 2310 includes main surfaces 2310e and 2310f that extend in a plane (XY plane) intersecting the stacking direction (Z direction) of the laminate 2100 and facing each other, and side surfaces 2310a to 2310d that are arranged to connect the main surfaces 2310e and 2310f.

[0069] The peripheral edge 2330 is formed when the laminate film 2320 is open and the portions where recesses 2320c and 2320d are not formed overlap each other. In another embodiment, one of the four outer sides of the peripheral edge 2330, side 2330a, is included in the folded portion a formed when the laminate film 2320 is folded back, and one part of the housing portion 2310 (side surface 2310a) includes a portion of the folded portion a along it.

[0070] In Figures 12 to 14, the folded portion a is depicted as wider to facilitate understanding, but the side surface 2310a of the housing portion 2310, including the folded portion a, is flat, as shown in Figure 1. In other words, while the peripheral portion 2330 extends from sides 2310b and 2310d of the housing portion 2310 in a direction approximately normal to the surface, the edge 2330a of the peripheral portion 2330 does not substantially extend from side surface 2310a.

[0071] As shown in Figure 15, the secondary battery is formed by housing a laminate 2100 in the recess 2320c of the laminate film 2320, to which lead terminals 2210, 2220 and current collector terminals 2230, 2240 are connected. As shown in Figures 13 and 14, the laminate film 2320 having the recess 2320c is folded back at the folded portion a, and the materials are joined together by adhesive or welding so as to include three sides 2330b to 2330d of the peripheral portion 2330.

[0072] In this joint, the edges 2330b and 2330d of the peripheral portion 2330 include sealing portions 2340 to 2350 that are joined to include them. Also in this joint, the peripheral portion 2330 that connects to the side surface 2310c of the housing portion 2310 has sealing portions 2370a to 2370c that are joined discontinuously toward the edge 2330c. The sealing portions 2370a to 2370c are substantially rectangular in shape, extending in the length direction (X direction) of the secondary battery 2000 and the width direction (Y direction) of the secondary battery 200 when viewed from the stacking direction (Z direction) of the laminate 210.

[0073] Between the sealed portions are unsealed portions where the materials are not joined together. Unsealed portions 2390a and 2390b are positioned between sealed portions 2370a and 2370b, and between sealed portions 2370b and 2370c, respectively.

[0074] The sealed portions 2370a to 2370c and the unsealed portions 2390a and 2390b correspond to the folded portion P20 that is folded along the housing portion 2310. The unsealed portions 2390a and 2390b correspond to the bent portion of the folded portion P20. In other words, the folded portion P20 is connected to one rectangular side of the housing portion 2310. Furthermore, as will be described later, the folded portion P20 extends along the side surface 2310c of the housing portion 2310 in a direction approximately horizontal (Z direction).

[0075] Figure 15 shows a configuration in which a folding portion P20 is provided at the top of the secondary battery 2000, and the side surface 2310a of the housing portion 2310, which includes a folded portion a, is flat at the bottom of the secondary battery 2000. However, a configuration in which a folding portion P10 is provided at the bottom of the secondary battery 2000, and the side surface 2310c of the housing portion 2310, which includes a folded portion a, is flat at the top of the secondary battery 2000, is also possible.

[0076] Furthermore, the secondary battery 2000 according to another embodiment has the same configuration and structure as the laminate 210 according to one embodiment shown in Figure 3. Also, the secondary battery 2000 according to another embodiment can replace the secondary battery 200 of the battery module 100 according to one embodiment shown in Figure 1, thereby constituting the battery module 1000. However, as described above, in the secondary battery 2000 according to another embodiment, either the upper or lower side is flat, and the other side has a structure that includes a folding portion. In other words, the first heat transfer member or the second heat transfer member will be in contact with the folding portion. Furthermore, the outer casing 2300 of the secondary battery 2000 according to another embodiment can employ the folding structure of the outer casing 230 according to one embodiment described using Figures 8 to 13 in the folding portion.

[0077] <Summary of Embodiments> The above embodiments disclose at least the following secondary batteries and battery modules.

[0078] 1. The secondary battery (2000) of the above embodiment is, A laminate (2100) comprising a positive electrode layer (2110, 2120), an electrolyte layer (2190), and a negative electrode layer (2130, 2140), The laminate (2100) is enclosed by an outer casing (2300), The exterior body (2300) is formed by folding a single material (2320) that forms the exterior body (2300) at the folded portion (a), The outer casing (2300) includes the folded portion (a) as a part thereof, a housing portion (2310) that houses the laminate (2100), and a peripheral portion (2330) around the housing portion (2310), The peripheral portion (2330) includes folding portions (P10, P20) that are folded along the housing portion (2310), In the aforementioned folding portions (P10, P20), the materials (2320) are not joined together on the bent portions (2380a, 2380b, 2390a, 2390b), but are joined together on the portions other than the bent portions (2380a, 2380b, 2390a, 2390b). According to this embodiment, since the peripheral edge is folded along the housing portion, the outer casing is easily made flat in this folded portion. Therefore, when this portion comes into contact with the heat transfer member, good contact can be achieved. Consequently, the secondary battery can be efficiently cooled or heated. In addition, since the outer casing is formed by folding a single material at the folded portion, the number of sealing points is reduced.

[0079] 2. The secondary battery (200) of the above embodiment is A laminate (210) comprising a positive electrode layer (211, 212), an electrolyte layer (219), and a negative electrode layer (213, 214), The laminate (210) is enclosed by an outer casing (230), The exterior body (230) is formed by overlapping two pieces of material (232a, 232b) that form the exterior body (230). The outer casing (230) includes a housing portion (231) that houses the laminate (210), and a peripheral portion (233) around the housing portion (231), The peripheral portion (233) includes folding portions (P1, P2) that are folded along the housing portion (231), In the aforementioned folding portions (P1, P2), the materials (232a, 232b) are not joined together on the bent portions (238a, 238b, 239a, 239b), but are joined together on areas other than the bent portions (238a, 238b, 239a, 239b). According to this embodiment, since the peripheral edge is folded along the housing, the outer casing is easily flattened in this folded portion. Therefore, when this portion comes into contact with the heat transfer member, it can make good contact. Consequently, the secondary battery can be efficiently cooled or heated. Furthermore, since the outer casing is formed by overlapping two materials, the outer casing can be easily manufactured.

[0080] 3. In the above embodiment, The housing portion (2310) has a rectangular shape when viewed from the stacking direction of the laminate (2100). The folding sections (P10, P20) are connected to one rectangular side of the storage section (2310). According to this embodiment, the upper and lower sides of the secondary battery can be efficiently cooled or heated. In other words, the heat transfer path (cross-sectional area of ​​heat transfer) from the secondary battery, or the heat transfer path (cross-sectional area of ​​heat transfer) to the secondary battery, is increased, allowing the secondary battery to be efficiently cooled or heated.

[0081] 4. In the above embodiment, The housing portion (231) has a rectangular shape when viewed from the stacking direction of the laminate (210), The folding sections (P1, P2) are connected to two rectangular sides of the storage section (231). According to this embodiment, the upper and lower sides of the secondary battery can be efficiently cooled or heated. In other words, compared to the case where the upper and lower sides of the secondary battery are not provided with folding parts, the heat transfer path (cross-sectional area of ​​heat transfer) from the secondary battery, or the heat transfer path (cross-sectional area of ​​heat transfer) to the secondary battery, is increased, allowing the secondary battery to be efficiently cooled or heated.

[0082] 5. In the above embodiment, The aforementioned folding parts (P1, P2, P10, P20) are A first region (R1) extending from the connection portion with the aforementioned housing portion (231, 2310) to one side in the stacking direction of the laminate (210, 2100), A second region (R2) extends from one end of the first region (R1) to the other side opposite to the first side, Includes. According to this embodiment, the folding portion is bent to form multiple regions, which makes it easier to reduce the unevenness of the contact surface between the secondary battery and the heat transfer member. As a result, gaps are less likely to occur between the secondary battery and the heat transfer member, and the secondary battery and the heat transfer member can be more closely fitted together, allowing the secondary battery to be cooled efficiently.

[0083] 6. In the above embodiment, The folding portions (P1, P2, P10, P20) include a third region (R3) that extends to the one side from the other end of the second region (R2) to the edge of the peripheral portion (233, 2330). According to this embodiment, the height of the folding section is stabilized, and the contact between the secondary battery and the heat transfer element can be improved.

[0084] 7. According to the above embodiment, The first region (R1) and the third region (R3) are located closer to the laminate (210, 2100) than the second region (R2). According to this embodiment, the folding portion and the heat transfer member come into contact in a second region, making it less likely for steps or other irregularities to form on these contact surfaces. Therefore, the adhesion between the secondary battery and the heat transfer member can be improved.

[0085] 8. According to the above embodiment, The second region (R2) extends in the stacking direction from the position of one end of the stack (210, 2100) to the position of the other end. According to this embodiment, a second region extends over substantially the entire stacking direction above or below the laminate, so that the contact surface with the heat transfer member in the secondary battery can be formed in the second region. Therefore, the adhesion between the secondary battery and the heat transfer member can be improved.

[0086] 9. According to the above embodiment, The length from the connection point between the folding portion (P1, P2, P10, P20) and the storage portion (231, 2310) to the edge of the folding portion (P1, P2, P10, P20) is approximately twice the length of the laminated body (210, 2100) in the stacking direction. According to this embodiment, in the stacking direction of the laminate, the sum of the lengths of the first and third regions is approximately equal to the sum of the lengths of the second region. Therefore, the adhesion between the secondary battery and the heat transfer member can be improved.

[0087] 10. According to the above embodiment, A highly viscous fluid (440) is applied to the folding parts (P1, P2, P10, P20). According to this embodiment, it is possible to suppress the formation of an air layer between the components when the folding part is folded, thereby improving heat transfer.

[0088] 11. The battery module (100) of the above embodiment is A secondary battery (200, 2000) as described in any of items 1 to 10 above, The system includes a cooling / heating means (410) for cooling or heating the secondary batteries (200, 2000). According to this embodiment, a battery module is provided in which a secondary battery is efficiently cooled or heated.

[0089] 12. According to the above embodiment, A first heat transfer member (420) is disposed between the secondary battery (200, 2000) and the cooling / heating means (410), The device comprises a second heat transfer member (430) positioned on the opposite side of the first heat transfer member (420) with the secondary batteries (200, 2000) in between, The second heat transfer member (430) comes into contact with the folding portion (P2, P20). According to this embodiment, a battery module is provided in which a secondary battery is efficiently cooled or heated.

[0090] 13. According to the above embodiment, the battery module (100) is: The secondary battery (200) described in 2 or 4 above, The system comprises a cooling / heating means (410) for cooling or heating the secondary battery (200). According to this embodiment, a battery module is provided in which a secondary battery is efficiently cooled or heated.

[0091] 14. According to the above embodiment, A first heat transfer member (420) is disposed between the secondary battery (200) and the cooling / heating means (410), The system comprises a second heat transfer member (430) positioned on the opposite side of the first heat transfer member (420) with the secondary battery (200) in between, The first heat transfer member (420) and the second heat transfer member (430) come into contact with the folding portions (P1, P2). According to this embodiment, a battery module is provided in which a secondary battery is efficiently cooled or heated.

[0092] Although embodiments of the invention have been described above, the invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the invention. [Explanation of symbols]

[0093] 100 Battery module, 200, 2000 Secondary battery, 210, 2100 Laminate, 211, 212 Positive electrode layer, 213, 214 Negative electrode layer, 215 Positive electrode active material layer, 216 Positive electrode current collector, 217 Negative electrode active material layer, 218 Negative electrode current collector, 219 Electrolyte layer, 221, 222, 2210, 2220 Lead terminals, 223, 224, 2230, 2240 Current collector terminals, 230, 2300 Outer casing, 231, 2310 Housing section, 231a to 231d, 2310a to 2310d Side view of housing section, 231e, 231f, 2310e, 2310f Main surface of housing section, 232a, 232b, 2320 Laminate film, 233, 2330 Peripheral portion, 233a to 233d, 2330a to 2330d Edge of peripheral portion, 234, 235, 236a to 236d, 237a to 237d Sealed portion, 238a, 238b, 239a, 239b Unsealed portion (folded portion), 232c, 232d, 2320c, 2320d Recess, 300 Separator, 410 Cooling / heating means, 411 Plate-shaped member, 412 Fluid passage, 420 First heat transfer member, 430 Second heat transfer member, 440 High viscosity fluid, 500 End plate, 510 Fastening bolt, 600 Installation portion, 610 Female thread portion, a Folded portion

Claims

1. A laminate comprising a positive electrode layer, an electrolyte layer, and a negative electrode layer, The laminate comprises an outer casing that encloses the laminate, The exterior body is formed by folding a single material that forms the exterior body at the folded portion, The exterior body includes the folded portion as part thereof, a housing portion that houses the laminate, and a peripheral portion around the housing portion. The aforementioned peripheral portion includes a folding portion that is folded along the aforementioned housing portion, In the aforementioned folding portion, the materials are not joined together at the bent portion, but are joined together at the other parts of the folding portion. A secondary battery wherein the folding portion includes a first region extending from a connection portion with the housing portion to one side in the stacking direction of the laminate, and a second region extending from one end of the first region to the other side opposite to the first side, and a highly viscous fluid is applied between the opposing surfaces of the material of the first region and the second region.

2. A laminate comprising a positive electrode layer, an electrolyte layer, and a negative electrode layer, The laminate comprises an outer casing that encloses the laminate, The exterior body is formed by overlapping two materials that make up the exterior body. The exterior body includes a housing portion that houses the laminate and a peripheral portion around the housing portion. The aforementioned peripheral portion includes a folding portion that is folded along the aforementioned housing portion, In the aforementioned folding portion, the materials are not joined together at the bent portion, but are joined together at the other parts of the folding portion. A secondary battery wherein the folding portion includes a first region extending from a connection portion with the housing portion to one side in the stacking direction of the laminate, and a second region extending from one end of the first region to the other side opposite to the first side, and a highly viscous fluid is applied between the opposing surfaces of the material of the first region and the second region.

3. The housing portion has a rectangular shape when viewed from the stacking direction of the laminate, The secondary battery according to claim 1, wherein the folding portion is connected to one side of the rectangular housing portion.

4. The housing portion has a rectangular shape when viewed from the stacking direction of the laminate, The secondary battery according to claim 2, wherein the folding portion is connected to two rectangular sides of the housing portion.

5. The secondary battery according to any one of claims 1 to 4, wherein the folding portion includes a third region extending to the one side from the other end of the second region to the edge of the peripheral portion.

6. The secondary battery according to claim 5, wherein the first region and the third region are located closer to the laminate than the second region.

7. The secondary battery according to any one of claims 1 to 6, wherein the second region extends in the stacking direction from the position of one end of the stack to the position of the other end of the stack.

8. The secondary battery according to any one of claims 1 to 7, wherein the length from the connection point between the folding portion and the housing portion to the edge of the folding portion is approximately twice the length in the stacking direction of the laminate.

9. A secondary battery according to any one of claims 1 to 8, A battery module comprising a cooling / heating means for cooling or heating the secondary battery.

10. A first heat transfer member is disposed between the secondary battery and the cooling / heating means, The system comprises a second heat transfer member positioned on the opposite side of the first heat transfer member, with the secondary battery in between, The battery module according to claim 9, wherein the second heat transfer member is in contact with the folding portion.

11. A secondary battery according to claim 2 or 4, A battery module comprising a cooling / heating means for cooling or heating the secondary battery.

12. A first heat transfer member is disposed between the secondary battery and the cooling / heating means, The system comprises a second heat transfer member positioned on the opposite side of the first heat transfer member, with the secondary battery in between, The battery module according to claim 11, wherein the first heat transfer member and the second heat transfer member are in contact with the folding portion.

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