Battery pack

Abstract

This technology provides a way to achieve restraint and cooling in battery packs with a simple structure. [Solution] The battery pack may include a first battery module and a second battery module arranged in a stacked configuration, and a cooling plate positioned between the first battery module and the second battery module. Each of the first and second battery modules may have a cell stack in which a plurality of battery cells are stacked, and a frame made of resin that surrounds the periphery of the cell stack in a frame shape. The frame of the first battery module is provided with a protrusion that projects toward the second battery module, and the frame of the second battery module may be provided with a recess that receives the protrusion of the first battery module. The cooling plate may be provided with holes or notches through which the protrusion passes.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a battery pack in which a plurality of battery modules are stacked. The plurality of battery modules are constrained to each other using a restraint. Also, a gap is formed using a spacer between adjacent battery modules to allow cooling air to pass through.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, in a battery pack in which a plurality of battery modules are stacked, it is necessary to constrain the plurality of battery modules to each other and effectively cool each battery module. This specification provides a technology for realizing such constraint and cooling with a simple structure.

Means for Solving the Problems

[0005] The technology disclosed herein is embodied in a battery pack. In a first aspect of this technology, the battery pack may include a first battery module and a second battery module arranged in a stacked configuration, and a cooling plate positioned between the first battery module and the second battery module. Each of the first and second battery modules may include a cell stack in which a plurality of battery cells are stacked, and a frame made of resin that surrounds the periphery of the cell stack in a frame-like manner. The frame of the first battery module is provided with a projection that protrudes toward the second battery module, and the frame of the second battery module may be provided with a recess that receives the projection of the first battery module. The cooling plate may be provided with holes or notches through which the projection passes.

[0006] In the battery pack described above, each battery module comprises a cell stack and a frame around its periphery. The frame of the first battery module has a protrusion, and the frame of the second battery module has a recess into which the protrusion fits. With this configuration, the two battery modules can be restrained from each other with a simple structure without the need for other restraints. In addition, a cooling plate is placed between the two battery modules, and the cooling plate has a hole or notch through which the protrusion of the first battery module passes. With this configuration, the cooling plate can be placed opposite the frame of each battery module, avoiding only the parts where the protrusion is located. As a result, not only the cell stack but also the frame can be directly cooled by the cooling plate, and each battery module can be cooled effectively.

[0007] In a second aspect of this technology, in addition to the first aspect described above, the frame of the first battery module may be provided with a plurality of protrusions, and the frame of the second battery module may be provided with a plurality of recesses. With such a configuration, relative displacement between the two battery modules is suppressed.

[0008] In a third aspect of this technology, in addition to the first or second aspect described above, the frame of the second battery module may be further provided with a protrusion that projects toward the first battery module. The frame of the first battery module may be further provided with a recess that receives the protrusion of the second battery module. In this case, the cooling plate may be further provided with a hole or notch through which the protrusion provided on the frame of the second battery module passes. That is, each of the two battery modules may be provided with both a protrusion and a recess.

[0009] In a fourth aspect of this technology, in addition to any one of the first to fourth aspects described above, the cooling plate may extend to the outer peripheral edge of the frame of the first battery module and the outer peripheral edge of the frame of the second battery module. That is, when viewed from above, the outer shape of the cooling plate may be greater than or equal to the outer shape of the first battery module and greater than or equal to the outer shape of the second battery module. With such a configuration, when a collision load is applied to the battery pack from the side due to a vehicle collision, part or all of the collision load is transmitted to the cooling plate, thereby reducing the collision load applied to the battery module. [Brief explanation of the drawing]

[0010] [Figure 1] A side view of the battery pack of the embodiment is shown. [Figure 2] A disassembled perspective view of the battery pack is shown. [Figure 3] Figure 1 shows a cross-sectional view along line III-III. [Figure 4] The results of various performance evaluation tests for the battery pack are shown. [Figure 5] The results of various performance evaluation tests for the battery pack are shown. [Figure 6] A side view of a modified battery pack is shown. [Modes for carrying out the invention]

[0011] The battery pack of this embodiment will be described with reference to Figures 1 to 5. The battery pack 10 is mounted on a vehicle that drives its wheels with a motor, for example. The battery pack 10 supplies power to the vehicle's motor. Examples of vehicles on which the battery pack 10 is mounted include battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like.

[0012] In this drawing, the vertical direction of the battery pack 10 is the Z direction, the direction in which the longer side of the top surface of the battery pack 10 extends is the X direction, and the direction in which the shorter side of the top surface of the battery pack 10 extends is the Y direction. Although not particularly limited, the battery pack 10 is positioned under the floor of the vehicle such that the Z direction is the vertical direction of the vehicle, the X direction is the longitudinal direction of the vehicle, and the Y direction is the lateral direction (vehicle width direction) of the vehicle. However, these directions are just examples and do not limit the orientation or posture of the battery pack 10 when in use.

[0013] As shown in Figures 1 and 2, the battery pack 10 comprises a plurality of battery modules 12, 14, 16, and 18, and a plurality of cooling plates 22, 24. The plurality of battery modules 12, 14, 16, and 18 include a first battery module 12, a second battery module 14, a third battery module 16, and a fourth battery module 18. Each of the plurality of battery modules 12 has a flattened rectangular parallelepiped shape that is shorter in the vertical direction (i.e., the Z direction in Figure 1). The plurality of battery modules 12, 14, 16, and 18 are stacked in the vertical direction. Specifically, the second battery module 14 is placed on the first battery module 12. The third battery module 16 is placed on the second battery module 14. The fourth battery module 18 is placed on the third battery module 16. However, the number of battery modules is not limited to four, but may be two, three, or five or more.

[0014] Each of the multiple battery modules 12, 14, 16, and 18 has a cell stack 30 and a frame 32. Although not particularly limited, the multiple battery modules 12, 14, 16, and 18 have the same configuration. The individual configurations of the battery modules 12, 14, 16, and 18 are described below.

[0015] The cell stack 30 generally has the shape of a flattened rectangular parallelepiped (or a thick plate). The cell stack 30 has a structure in which multiple battery cells are stacked in the Z direction. Each of the multiple battery cells is a secondary battery cell configured to be rechargeable and dischargeable. The secondary battery cell is not particularly limited, but may be, for example, a lithium-ion battery cell or an all-solid-state battery cell. Each of the multiple battery cells has a rectangular sheet shape.

[0016] The frame 32 is a rectangular frame-shaped member. The frame 32 surrounds the periphery of the cell stack 30 in a frame-like manner. By surrounding the cell stack 30 with the frame 32, moisture is prevented from entering each battery cell of the cell stack 30 from the outside. The frame 32 is made of a resin material. For example, a thermoplastic resin such as polyethylene resin is used as the resin material that makes up the frame 32. The frame 32 has a plurality of protrusions 32p arranged on its upper surface (i.e., the surface facing the +Z direction). Each of the plurality of protrusions 32p protrudes in the +Z direction and extends toward the second battery module 14. The frame 32 has a plurality of recesses 32r arranged on its lower surface (i.e., the surface facing the -Z direction). The plurality of recesses 32r in each battery module 12, 14, 16, 18 are arranged in the same position as the plurality of protrusions 32p in the XY plane. Each of the multiple recesses 32r has a hole capable of receiving the corresponding multiple protrusions 32p of a battery module positioned adjacent to it downward (i.e., in the -Z direction). That is, the recesses 32r of the second battery module 14 fit with the protrusions 32p of the first battery module 12.

[0017] The specific configurations of the convex portions 32p and the concave portions 32r are not particularly limited. Each of the convex portions 32p and the concave portions 32r is not limited to a plurality, and may be one. Each convex portion 32p has a dome shape, and the holes of each concave portion 32r have the same dome shape. However, each concave portion 32r only needs to be formed so as to fit with the corresponding convex portion 32p, and the shapes of the convex portion 32p and the concave portion 32r are not particularly limited. For example, the holes of the convex portion 32p and the concave portion 32r may have different shapes from each other. Alternatively, one of the plurality of convex portions 14p may have the same shape as, or a different shape from, the other convex portions 14p of the plurality of convex portions 14p.

[0018] Each of the plurality of cooling plates 20, 22 is a plate-shaped member. Each cooling plate 20, 22 is formed using a metal material such as aluminum. The plurality of cooling plates 20, 22 includes a first cooling plate 20 and a second cooling plate 22.

[0019] The first cooling plate 20 is disposed between the first battery module 12 and the second battery module 14. The first cooling plate 20 reaches the outer peripheral edge of the frame 32 of the first battery module 12 and the outer peripheral edge of the frame 32 of the second battery module 14. That is, as shown in FIG. 3, when viewed in plan, the outer shape of the first cooling plate 20 is larger than the outer shape of the first battery module 12. Although not shown in FIG. 3, the second battery module 14 has the same outer shape as the first battery module 12. That is, the outer shape of the first cooling plate 20 is also larger than the outer shape of the second battery module 14.

[0020] The first cooling plate 20 has a through hole 20h that penetrates the first cooling plate 20 in the Z direction. The convex portion 32p of the first battery module 12 passes through the through hole 20h of the first cooling plate 20. Therefore, the convex portion 32p of the first battery module 12 passes through the through hole 20h of the first cooling plate 20 and fits into the concave portion 32r of the second battery module 14. The opening area of the through hole 20h is larger than the maximum cross-sectional area of the cross-section of the convex portion 32p. The cross-section referred to here refers to the cross-section when the convex portion 32p is cut by the XY plane (i.e., a plane perpendicular to the Z direction). More specifically, the opening area of the through hole 20h may be 1.1 times or more of the maximum cross-sectional area of the cross-sectional area of the convex portion 32p. Furthermore, the opening area of the through hole 20h may be 2.5 times or less of the maximum cross-sectional area of the cross-sectional area of the convex portion 32p. According to such a configuration, the fitting property of the convex portion 32p into the through hole 20h of the cooling plate 20 is good. Also, it can sufficiently exert an effect on suppressing the displacement of the plurality of battery modules 12 and 14. Although not particularly limited, the through hole 20h has the same shape as the cross-section of the convex portion 32p. However, the through hole of the cooling plate may have a shape different from the cross-section of the convex portion 32p. Note that the first cooling plate is not limited to the through hole, and in the first cooling plate, it may have a notch that penetrates in the Z direction and opens in the X direction or the Y direction. In this case, the convex portion 32p of the first battery module 12 may pass through the notch of the first cooling plate.

[0021] The second cooling plate 22 is disposed between the third battery module 16 and the fourth battery module 18. The second cooling plate 22 can be configured in the same manner as the first cooling plate 20. The second cooling plate 22 has a through hole 22h similar to the through hole 20h of the first cooling plate 20. The convex portion 32p of the third battery module 16 passes through the through hole 22h of the second cooling plate 22.

[0022] Cooling channels (not shown) are formed on each of the two opposite surfaces of each of the cooling plates 20 and 22 in the Z direction. A refrigerant passes through the cooling channels. The cooling channels are arranged in a portion of each of the cooling plates 20 and 22 where the through holes 20h and 22h are not provided (for example, an inner portion than the through holes 20h and 22h).

[0023] In this embodiment, no cooling plate is placed between the second battery module 14 and the third battery module 16. The protrusion 32p of the second battery module 14 directly engages with the recess 32r of the second battery module 14. However, the number of cooling plates 20 and 22 is not limited to two. For example, the battery pack may include a third cooling plate placed between the second battery module 14 and the third battery module 16. In this case, the protrusion 32p of the second battery module 14 may pass through the through hole of the third cooling plate and directly engage with the recess 32r of the second battery module 14. In addition, the battery pack may include a fourth cooling plate placed below the first battery module 12 or above the fourth battery module. In this case, each cooling plate may have a cooling channel formed on only one side.

[0024] Typically, in battery packs where multiple battery modules are stacked, the modules are constrained from one another using separate restraints. However, in this embodiment, when multiple battery modules 12, 14, 16, and 18 are arranged vertically in the vehicle, the battery pack 10 is located under the vehicle floor. As a result, the height under the vehicle floor increases due to the separate restraints, reducing the passenger compartment space. Therefore, a simple structure is required to restrain the multiple battery modules so that the vertical dimension (i.e., the Z-direction) of the battery pack 10 does not increase.

[0025] In this embodiment, each battery module (e.g., 12, 14) comprises a cell stack 30, and a frame 32 is provided around its periphery. The frame 32 of the first battery module 12 is provided with a protrusion 32p, and the frame 32 of the second battery module 14 is provided with a recess 32r into which the protrusion 32p fits. With this configuration, the two battery modules 12 and 14 can be restrained from each other with a simple structure without the need for other restraining devices.

[0026] On the other hand, the battery pack 10 mounted on the vehicle is prone to generating heat due to repeated rapid charging. However, when cooling each battery module 12, 14 by a cooling plate placed between the two battery modules 12, 14 as in this embodiment, the cooling plate is placed inside the frame 32, avoiding the area where the protrusion 32p provided on the frame 32 exists. In other words, the cooling plate becomes smaller than the frame 32. In this case, there is a risk that the cooling capacity of the battery module frame 32 will be insufficient.

[0027] In this embodiment, in addition to the above-described configuration, a first cooling plate 20 is placed between two battery modules (for example, 12 and 14), and the first cooling plate 20 is provided with a plurality of through holes 20h through which the protrusions 32p of the first battery module 12 pass. With this configuration, the first cooling plate 20 can be placed facing the frame 32 of each battery module 12 and 14, while avoiding only the portion where the protrusions 32p are located. As a result, not only the cell stack 30 but also the frame 32 can be directly cooled by the first cooling plate 20, and each battery module 12 and 14 can be effectively cooled.

[0028] In particular, in this embodiment, the frame 32 of the first battery module 12 is provided with multiple protrusions 32p, and the frame 32 of the second battery module 14 is provided with multiple recesses 32r. With this configuration, relative displacement between the two battery modules 12 and 14 is suppressed.

[0029] In this embodiment, as described above, when viewed from above, the outer shape of the first cooling plate 20 is greater than or equal to the outer shape of the first battery module 12 and greater than or equal to the outer shape of the second battery module 14 (see Figure 3). With this configuration, when a collision load acts on the battery pack 10 from the side (i.e., in the X or Y direction) due to a vehicle collision, part or all of the collision load is transmitted to the first cooling plate 20, thereby reducing the collision load applied to the battery modules 12 and 14. Furthermore, the peripheral edges of the battery modules 12 and 14 are constrained by a plurality of protrusions 32p and recesses 32r. Therefore, even if vibrations occur in the vertical direction (i.e., in the Z direction) when the vehicle is running, these vibrations suppress the vibration of the peripheral edges of each battery module 12 and 14. As a result, vertical vibrations of each battery module 12 and 14 themselves are suppressed, and the impact on each battery cell (such as the separation of the distance between the positive and negative electrodes) that may occur due to these vibrations is reduced.

[0030] Furthermore, the third battery module 16, the fourth battery module 18, and the second cooling plate 22 can achieve the same effects as the first battery module 12, the second battery module 14, and the first cooling plate 20.

[0031] (Examples) Examples will be described with reference to Figures 4 and 5. In each example, various performance evaluation tests of the battery pack were conducted and evaluated. In Example 1, a battery pack similar to that of the embodiment was manufactured as described below. First, multiple battery cells and cooling plates 20 and 22 having through holes 20h and 22h were prepared. Each battery cell used a monopolar cell in which the positive electrode was coated on both sides of a single positive electrode current collector foil and the negative electrode was coated on both sides of a negative electrode current collector foil. Multiple prepared battery cells were stacked vertically to create a cell stack 30. Next, a frame 32 was formed by solidifying the periphery of the cell stack 30 into a frame shape using polyethylene resin. Multiple battery cells were integrated by the frame 32 to create battery modules 12, 14, 16, and 18. The frame 32 of each battery module was provided with multiple protrusions 32p and multiple recesses 32r. The battery pack 10 was constructed by stacking the fabricated battery modules 12, 14, 16, and 18 and the cooling plates 20 and 22 in a vertical direction.

[0032] Note that the battery cell is not limited to a monopolar cell. A bipolar cell may also be used, in which a positive electrode current collector foil and a negative electrode current collector foil are bonded together with a conductive adhesive, and the positive and negative electrodes are coated on the front and back surfaces of the bonded current collector foils, respectively.

[0033] As shown in Figure 4(A), in Example 1 and Comparative Examples 1 and 2, the fabricated battery packs 10 were evaluated in a specified impact test and a rapid charging test. Details of the specified impact test and rapid charging test will be described later. In Comparative Example 1, a battery pack was fabricated without a cooling plate between the two battery modules, unlike in Example 1. In Comparative Example 2, a cooling plate without through holes was prepared, and the battery pack was prepared in the same manner as in Example 1. Since the cooling plate of Comparative Example 2 does not have through holes, the outer shape of the cooling plate is smaller than the outer shape of each battery module 12, 14, 16, and 18. Specifically, the outer shape of the cooling plate of Comparative Example 2 is located inside the protrusion 32p of each battery module.

[0034] (Standard crash test) In the standard collision test, battery modules 12, 14, 16, and 18 are collided horizontally at a predetermined collision acceleration, and the maximum displacement of battery modules 12, 14, 16, and 18 from their design positions is measured. Before the collision, the relative positions of the sides of the multiple battery modules 12, 14, 16, and 18 are flush, and in this case, the displacement is 0 mm. Compared to this state of 0 mm displacement of multiple battery modules 12, 14, 16, and 18, if the maximum displacement of the multiple battery modules 12, 14, 16, and 18 after the collision is less than 3 mm, the standard collision performance is judged as "○" (good), and if the maximum displacement is 3 mm or more, the standard collision performance is judged as "×" (bad).

[0035] In the standard crash test, the maximum displacement widths for Comparative Examples 1 and 2 were 20 mm and 16 mm, respectively, resulting in a "fail" judgment, while the maximum displacement width for Example 1 was 2 mm, resulting in a "pass" judgment. From the above, it was confirmed that by placing a cooling plate whose outer dimensions are greater than or equal to the outer dimensions of each battery module 12, 14, 16, and 18 between two battery modules, the positional displacement of multiple battery modules 12, 14, 16, and 18 can be suppressed.

[0036] (Rapid charging test) In the rapid charging test, the temperature at each location of the battery module (e.g., 18) is measured and the highest temperature is recorded when the battery is charged for a specified time at a predetermined rapid charging current. If the highest temperature measured at any location of the battery module 18 is 55°C or less, the rapid charging capability is judged as "○" (good), and if the highest temperature exceeds 55°C, the rapid charging capability is judged as "×" (bad).

[0037] In the rapid charging test, Comparative Example 1, lacking a cooling plate, reached the highest temperature of 80°C in the center of the battery module 18, resulting in the highest rating (judgment: "×"). This confirmed that the entire battery module 18 was not adequately cooled. Comparative Example 2, while equipped with a cooling plate, had a smaller outer diameter than each battery module. Consequently, the peripheral portion of the battery module 18 reached a maximum temperature of 65°C, indicating insufficient cooling (judgment: "×"). On the other hand, while Example 1 also showed a maximum temperature at the peripheral portion, similar to Comparative Example 2, its maximum temperature was the lowest at 48°C (judgment: "〇"). From the above, it was confirmed that by providing cooling plates 20 and 22 whose outer diameter is greater than or equal to the outer diameter of each battery module 12, 14, 16, and 18, the battery modules 12, 14, 16, and 18 can be adequately cooled, even to their peripheral portions.

[0038] As shown in Figure 4(B), in Examples 2 and 3 and Comparative Example 3, the specified impact test of the fabricated battery pack 10 was evaluated. In Comparative Example 3, compared with Example 1, the relationship between the height Hp of the protrusion of the battery module (i.e., the dimension in the Z direction) and the heights Hm of the battery modules 12, 14, 16, and 18 and the heights Hc of the cooling plates 20 and 22 is specified as Hp = 0.02 * (Hm + Hc). Similarly to Comparative Example 3, in Example 2, Hp = 0.05 * (Hm + Hc), in Example 3, Hp = 0.40 * (Hm + Hc), and in Example 4, Hp = 0.75 * (Hm + Hc).

[0039] In Comparative Example 3, the maximum displacement was 11 mm (judgment: "×"). In Example 2, the maximum displacement was small at 2 mm, and in Examples 3 and 4, the maximum displacement was 0 (all judgments: "〇"). From the above, it was confirmed that when the height Hp of the protrusions 32p of the battery modules 12, 14, 16, and 18 is between 5% and 75% of the sum of the heights Hm of the battery modules 12, 14, 16, and 18 and the heights Hc of the cooling plates 20 and 22, the positional displacement of multiple battery modules 12, 14, 16, and 18 is suppressed. Furthermore, it was confirmed that when the height Hp of the protrusions 32p of the battery modules 12, 14, 16, and 18 is 40% or more, it is more effective in suppressing the positional displacement of multiple battery modules 12, 14, 16, and 18.

[0040] As shown in Figure 5(A), in Examples 5-6 and Comparative Examples 4-5, the fitting test and the specified impact test were evaluated. The fitting test will be described later. In Comparative Example 4, compared to Example 4, the relationship between the opening area Sh of the through holes 20h and 22h of the cooling plates 20 and 22 and the cross-sectional area Sp of the protrusions 32p of the battery modules 12, 14, 16, and 18 is specified as Sh = 1.00 * Sp. Note that the cross-sections of the through holes 20h and 22h of the cooling plates 20 and 22 and the protrusions 32p of the battery modules 12, 14, 16, and 18 have the same circular shape. Similar to Comparative Example 4, in Example 5, Sh = 1.10 * Sp, in Example 6, Sh = 2.50 * Sp, and in Comparative Example 5, Sh = 2.70 * Sp.

[0041] (fitting test) In the fitting test, the fit between the through-hole 20h of the cooling plate (e.g., 20) and the protrusion 32p of the battery module (e.g., 12) during assembly of the battery pack 10 was evaluated. The fitting was judged as "○" if the cooling plate 20 was lowered relative to the battery module 12, and the cooling plate 20 and the battery module 12 were fitted together by the force of the cooling plate 20's own weight, and the fitting between the cooling plate 20 and the battery module 12 did not come undone when the cooling plate 20, which was fitted with the protrusion 32p of the battery module 12, was raised with a force 1.5 times its own weight. On the other hand, if the cooling plate 20 is lowered relative to the battery module 12 and the cooling plate 20 and the battery module 12 do not engage due to the force of the cooling plate 20's own weight, or if the engagement between the cooling plate 20 and the battery module 12 is disengaged when the cooling plate 20, which is engaged with the protrusion 32p of the battery module 12, is raised with a force 1.5 times its own weight, the engagement between the cooling plate 20 and the battery module 12 is judged as "×".

[0042] In the fitting test, the fitability in Comparative Example 4 was "×". Here, the opening area of ​​the through hole 20h of the cooling plate 20 is equal to the cross-sectional area Sp of the protrusion 32p of the battery module 12. In other words, there is no gap between the through hole 20h of the cooling plate 20 and the protrusion 32p of the battery module 12. Therefore, the protrusion 32p cannot easily pass through the through hole 20h of the cooling plate 20. On the other hand, the fitability in Examples 5 and 6 was "〇". However, the fitability in Comparative Example 7 was "×". From the above, it was confirmed that the fitability is excellent when the opening area Sh of the through holes 20h and 22h of the cooling plates 20 and 22 is 1.1 times or more and 2.5 times or less of the cross-sectional area of ​​the protrusion 32p of the battery modules 12, 14, 16, and 18.

[0043] In the standard crash test, the maximum displacement widths in Examples 5 and 6 were 0 and 2 mm, respectively, resulting in a "fail" judgment, whereas in Comparative Example 5, the maximum displacement width was 5 mm, resulting in a "pass" judgment. From the above, it was confirmed that when the opening area Sh of the through holes 20h and 22h in the cooling plates 20 and 22 is 1.1 times or more and 2.5 times or less of the cross-sectional area of ​​the protrusions 32p of the battery modules 12, 14, 16, and 18, it is more effective in suppressing the positional displacement of multiple battery modules 12, 14, 16, and 18. Note that the standard crash test was not performed in Comparative Example 4.

[0044] As shown in Figure 5(B), the horizontal impact test was evaluated. The horizontal impact test will be described later. In Comparative Example 6, compared to Example 1, the relationship between the area Sc of the cooling plates 20 and 22 and the area Sm of the battery modules 12, 14, 16, and 18 is specified as Sc = 0.85 * Sm. Similar to Comparative Example 6, in Comparative Example 7, Sc = 0.96 * Sm, in Example 7, Sc = 1.00 * Sm, and in Example 8, Sc = 1.07 * Sm.

[0045] (Horizontal collision test) In the horizontal impact test, the battery pack 10 is crushed by external pressure in the horizontal direction (i.e., the XY plane direction). The voltage of each cell is measured, and the number of cells that short-circuit when a crusher is pressed in under specified crushing conditions is measured. If fewer than 5 cells short-circuit, the horizontal impact resistance is judged as "○", and if 5 or more cells short-circuit, the horizontal impact resistance is judged as "×".

[0046] In Comparative Examples 6 and 7, the area Sc of the cooling plates 20 and 22 was smaller than the area Sm of the battery modules 12, 14, 16, and 18, and the number of short-circuited cells was 120 and 11, respectively (judgment: "×"). On the other hand, in Examples 7 and 8, the area Sc of the cooling plates 20 and 22 was greater than or equal to the area Sm of the battery modules 12, 14, 16, and 18, and the number of short-circuited cells was small, 3 and 0, respectively (judgment: "〇"). This suggests that when the area Sc of the cooling plates 20 and 22 is greater than or equal to the area Sm of the battery modules 12, 14, 16, and 18, that is, when the outer dimensions of the cooling plates 20 and 22 are greater than or equal to the outer dimensions of the battery modules 12, 14, 16, and 18, some or all of the crushing load is transmitted to the cooling plates 20 and 22 before the battery modules 12, 14, 16, and 18, and the crushing load applied to the battery modules 12, 14, 16, and 18 is reduced.

[0047] (Modified Version) Referring to Figure 6, a modified version with a different configuration from the first embodiment will be described. The modified battery pack 110 may comprise a plurality of modules 112, 114, 116, and 118. Each of the plurality of modules 112, 114, 116, and 118 may have a different configuration of the frame 132. In the frame 132, some of the plurality of recesses 32r of the embodiment arranged on the bottom surface (i.e., the surface facing the -Z direction) may be changed to a plurality of protrusions 132p. The plurality of recesses 32r and the plurality of protrusions 132p may be arranged alternately along the periphery of the frame 32. The plurality of protrusions 132p may extend toward a battery module arranged adjacently below. In the frame 132, some of the plurality of protrusions 32p of the embodiment arranged on the top surface (i.e., the surface facing the +Z direction) may be changed to a plurality of recesses 132r. The plurality of protrusions 32p and the plurality of recesses 132r may be arranged alternately along the periphery of the frame 32. Each of the multiple recesses 132r may have a hole capable of receiving a corresponding protrusion 132p of a battery module positioned adjacent to it above (i.e., in the +Z direction). That is, the recess 132r of the first battery module 112 may engage with the protrusion 132p of the second battery module 114 through the cooling plate 20. Even in such a configuration, the two battery modules (112 and 114 / 116 and 118) can be constrained from each other with a simple structure. At the same time, not only the cell stack 30 but also the frame 132 can be directly cooled by the cooling plates 20 and 22, and each battery module 112, 114, 116, and 118 can be effectively cooled. [Explanation of symbols]

[0048] 10, 110: Battery pack; 12, 14, 16, 18, 112, 114, 116, 118: Battery module; 20, 22: Cooling plate; 20, 22h: Through hole; 30: Cell stack; 32, 132: Frame; 32p, 132p: Protrusion; 32r, 132r: Recess

Claims

1. It is a battery pack, A first battery module and a second battery module are stacked together, A cooling plate is disposed between the first battery module and the second battery module, Equipped with, Each of the first battery module and the second battery module is: A cell stack in which multiple battery cells are stacked, It is made of resin and has a frame that surrounds the periphery of the cell laminate in a frame shape, The frame of the first battery module is provided with a protrusion that extends toward the second battery module. The frame of the second battery module is provided with a recess for receiving the protrusion of the first battery module. The cooling plate is provided with a hole or notch through which the protrusion passes. Battery pack.

2. The frame of the first battery module is provided with a plurality of the protrusions, The battery pack according to claim 1, wherein the frame of the second battery module is provided with a plurality of recesses.

3. The frame of the second battery module is further provided with a protrusion that extends toward the first battery module. The frame of the first battery module is further provided with a recess for receiving the protrusion of the second battery module. The battery pack according to claim 1, wherein the cooling plate is further provided with a hole or notch through which the protrusion provided on the frame of the second battery module passes.

4. The battery pack according to any one of claims 1 to 3, wherein the cooling plate reaches the outer peripheral edge of the frame of the first battery module and the outer peripheral edge of the frame of the second battery module.

Images