Battery module

Abstract

To provide a battery module that can improve energy density during charging. [Solution] The second elastic member consists of four layers of corrugated leaf springs W stacked in the stacking direction of the battery cell stack. The corrugated leaf springs W have curved surfaces C having a single radius of curvature arranged continuously via flat surfaces F and extend in a predetermined direction. The surface of the flat surfaces F is substantially parallel to the tangent plane at the end of the curved surfaces C that is arranged continuously with the flat surfaces F. If the radius of curvature of the curved surfaces C is r[mm], and the radius of curvature of the curved surfaces when the height H and the pitch P of the curved surfaces C are not changed, and the curved surfaces having a single radius of curvature are arranged alternately and continuously without passing through the flat surfaces F, then the equation 0.50 ≤ r / r0 ≤ 0.90 It satisfies the condition.

Description

[Technical Field]

[0001] This invention relates to a battery module. [Background technology]

[0002] In recent years, research and development has been conducted on battery modules that contribute to energy efficiency, in order to ensure that many people have access to affordable, reliable, sustainable, and advanced energy.

[0003] Because battery cells expand and contract during charging and discharging, a battery module includes, for example, a pair of end plates provided at both ends of the stacking direction of the battery cell stack, and a binding bar that restrains the battery cell stack between the pair of end plates.

[0004] Patent Document 1 describes a battery spacer that is placed between two battery cells facing each other. The battery spacer has a corrugated cross-sectional shape with continuous peaks and valleys, with the side facing one of the two battery cells being the peak side and the side facing the other being the valley side, and comprises pressure-receiving surfaces located at the peaks of the corrugated shape of the base that appear on the peak side and the valley side, respectively, and making surface contact with the two battery cells, and a buffer portion that connects the pressure-receiving surfaces located on the peak side and the valley side in an alternating manner to form the corrugated shape. Furthermore, the buffer portion is given an alternating barrel shape to the corrugated shape, with the width increasing from both ends of the pressure-receiving surface to the maximum width of the buckling bend portion, and an arrangement interval that secures space for the buckled bend portion between adjacent bend portions on the same side. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-066882 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the battery spacer described in Reference 1 has a predetermined height when it is compressed as the battery cell expands during charging, resulting in a lower energy density during battery charging.

[0007] The present invention aims to provide a battery module capable of improving energy density during charging. [Means for solving the problem]

[0008] (1) A battery cell stack comprising a plurality of battery cells stacked together, a pair of plate-shaped members provided at both ends of the stacking direction of the battery cell stack, and an elastic member disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped members, wherein the elastic member comprises a pair of first elastic members disposed on both outer sides in the stacking direction of the battery cell stack, and a second elastic member disposed between the pair of first elastic members, wherein the second elastic member has a corrugated leaf spring arranged in 2N layers in the stacking direction of the battery cell stack (where N r is a natural number.) The corrugated leaf spring is stacked, and the corrugated leaf spring has curved surfaces having a single radius of curvature arranged continuously via a flat section, and extends in a predetermined direction, the surface of the flat section is substantially parallel to the tangent plane at the end of the curved surface that is arranged continuously with the flat section, and the radius of curvature of the curved surface is r[mm], and in the corrugated leaf spring, if the height and the pitch of the curved surface are not changed and the curved surfaces having a single radius of curvature are arranged alternately and continuously without the flat section, then the equation 0.50 ≤ r / r0 ≤ 0.90 A battery module that satisfies the requirements.

[0009] Equation (2) 0.60 ≤ r / r0 ≤ 0.85 A battery module as described in (1) that satisfies the following conditions.

[0010] (3) Formula 0.70≦r / r0≦0.80 The battery module according to (2), which satisfies the above relation.

[0011] (4) In the battery module according to any one of (1) to (3), the second elastic member has a plurality of contact regions in contact with the first elastic member in the width direction, the wavy plate spring in contact at the contact regions has an extending portion that extends outward in the width direction from the outermost contact region in the width direction, and as the distance in the width direction from the outermost contact region in the width direction increases, the distance in the thickness direction from the first elastic member in contact at the contact region increases.

[0012] (5) The battery module according to (4), wherein in the wavy plate spring in contact at the contact regions, the length in the width direction between the top or bottom of the curved surface portion adjacent to the end of the extending portion and the end of the extending portion is larger than the length in the width direction between the adjacent bottom and top of the curved surface portion.

[0013] (6) The battery module according to any one of (1) to (5), wherein the wavy plate spring contains fiber-reinforced plastic.

[0014] (7) The battery module according to any one of (1) to (6), wherein the battery cell is a solid-state battery cell.

[0015] (8) The battery module according to any one of (1) to (7), wherein the battery cell includes a negative electrode mixture layer containing lithium metal or a lithium alloy. [Advantageous Effects of the Invention]

[0016] According to the present invention, a battery module capable of improving the energy density during charging can be provided. [Brief Description of the Drawings]

[0017] [Figure 1]This is a cross-sectional view showing a battery module according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the elastic member in Figure 1. [Figure 3] Figure 2 is a cross-sectional view showing a portion of a corrugated leaf spring. [Figure 4] Figure 3 is a cross-sectional view illustrating the case where the flat portion is omitted in a corrugated leaf spring, while keeping the height and the pitch of the curved portion unchanged. [Figure 5] This graph shows the relationship between the ratio of height h (h / h0) when a predetermined surface pressure is applied to height h0 when the surface pressure of the corrugated leaf spring is 0 MPa, and the surface pressure in Experimental Example 1 and Comparative Experimental Examples 1 and 2. [Figure 6] This is a cross-sectional view showing the corrugated leaf springs of Experimental Example 1 and Comparative Experimental Examples 1 and 2. [Figure 7] This graph shows the relationship between r / r0 and h / h0 when the surface pressure of a corrugated leaf spring is 2.5 MPa. [Figure 8] Figure 2 is a partially enlarged cross-sectional view of the elastic member. [Figure 9] Figure 2 is a cross-sectional view showing a corrugated leaf spring. [Figure 10] Figure 2 is a cross-sectional view illustrating the manufacturing method of the elastic member. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described below with reference to the drawings.

[0019] Figure 1 shows a battery module according to one embodiment of the present invention.

[0020] The battery module 10 comprises a battery cell stack 11 in which a plurality of battery cells 11a are stacked, a pair of plate-shaped end plates 12 provided at both ends of the battery cell stack 11 in the stacking direction, and a binding bar 13 as a restraining member that restrains the battery cell stack 11 between the pair of end plates 12. Here, the binding bar 13 is installed at two locations in the figure, at the top and bottom.

[0021] In the battery module 10, elastic members 14 are positioned between multiple battery cells 11a and between the battery cell stack 11 and the end plate 12.

[0022] The elastic member 14 may be positioned between multiple battery cells 11a, or between the battery cell stack 11 and the end plate 12.

[0023] As shown in Figure 2, the elastic member 14 comprises a pair of first elastic members 14a positioned on both outer sides in the stacking direction of the battery cell stack 11, and a second elastic member 14b positioned between the pair of first elastic members 14a. The second elastic member 14b consists of four layers of corrugated leaf springs W stacked in the stacking direction of the battery cell stack 11. This reduces the hysteresis loss of the elastic member 14. In this case, the second elastic member 14b has multiple contact areas A in the width direction D1 that are in contact with the first elastic members 14a.

[0024] Here, as the elastic member 14 is compressed due to the expansion of the battery cell 11a during charging, the first elastic member 14a is interposed between the battery cell 11a and the second elastic member 14b. As a result, the difference in surface pressure between the part of the first elastic member 14a that is in contact with the second elastic member 14b and the part of the first elastic member 14a that is not in contact with the second elastic member 14b becomes smaller, and the uniformity of surface pressure increases.

[0025] Furthermore, as shown in Figure 3, the corrugated leaf spring W has a curved surface C having a single radius of curvature arranged continuously via a flat surface F, and extends in the depth direction in the figure. In this case, the surface of the flat surface F is substantially parallel to the tangent plane at the end of the curved surface C that is arranged continuously with the flat surface F, and it is preferable that it is parallel. Also, the bottom and top of the curved surface C of adjacent corrugated leaf springs W are in contact with each other. Note that the bottom and top of the curved surface C are located on the curved surface C that is convex to the lower and upper sides in the stacking direction of the battery cell stack 11, respectively.

[0026] If the radius of curvature of the curved surface C is r [mm], and in a corrugated leaf spring W, if the height H and the pitch P of the curved surface C are not changed, and the flat section F is omitted, that is, if curved surfaces C0 having a single radius of curvature are arranged alternately in a continuous manner (see Figure 4), then the radius of curvature of the curved surface C0 is r0 [mm], then the formula 0.50 ≤ r / r0 ≤ 0.90 Satisfying the equation 0.60 ≤ r / r0 ≤ 0.85 It is preferable that the following conditions be met: 0.70 ≤ r / r0 ≤ 0.80 It is preferable that the following conditions are met. Since r / r0 is 0.5 or more and 0.9 or less, when the elastic member 14 is compressed as the battery cell 11a expands during charging, the height of the corrugated leaf spring W is reduced, and as a result, the energy density of the battery module 10 during charging is increased. At this time, H is not particularly limited, but for example, it is 1.0 mm or more and 3.0 mm or less. Also, P is not particularly limited, but for example, it is 6.0 mm or more and 16.0 mm or less. Furthermore, r0 is not particularly limited, but for example, it is 3.0 mm or more and 7.0 mm or less. The thickness of the flat part F and the curved part C, i.e., the thickness of the corrugated leaf spring W, is not particularly limited, but for example, it is 0.1 mm or more and 0.55 mm or less.

[0027] Figure 5 shows the relationship between the ratio of the height h when a predetermined surface pressure is applied (h / h0) to the height h0 when the surface pressure of a corrugated leaf spring is 0 MPa, and the surface pressure. Here, the corrugated leaf spring in Experimental Example 1 has curved sections C with a single radius of curvature arranged continuously via a flat section F (see Figure 6(a)). The corrugated leaf spring in Experimental Example 1 is made of glass fiber reinforced plastic. The corrugated leaf spring in Comparative Experimental Example 1 is the same as the corrugated leaf spring in Experimental Example 1, but without changing the height H and the pitch P of the curved sections C, except that the flat section F is omitted (see Figure 6(b)). Furthermore, the corrugated leaf spring in Comparative Experimental Example 2 is the same as the corrugated leaf spring in Experimental Example 1, but without changing the height H and the pitch P of the curved sections C, except that the radius of curvature r of the curved sections C is changed (see Figure 6(c)).

[0028] Figure 5 shows that the wavy leaf spring in Experimental Example 1 has a reduced h / h0 compared to the wavy leaf springs in Comparative Experimental Examples 1 and 2.

[0029] Furthermore, fiber-reinforced plastics other than glass fiber-reinforced plastics may be used. Examples of fiber-reinforced plastics other than glass fiber-reinforced plastics include, but are not limited to, carbon fiber-reinforced plastics.

[0030] Figure 7 shows the relationship between r / r0 and h / h0 when the surface pressure of a corrugated leaf spring is 2.5 MPa.

[0031] Figure 7 shows that when r / r0 is between 0.5 and 0.9, the h / h0 is reduced to 28% or less when the surface pressure is 2.5 MPa.

[0032] As described above, the second elastic member 14b has multiple contact areas A in the width direction D1 that are in contact with the first elastic member 14a. The corrugated leaf spring W that is in contact with the contact areas A has an extended portion E that extends outward in the width direction D1 from the outermost contact areas A on both sides in the width direction D (see Figure 8). In this case, the distance of the extended portion E in the width direction D2 from the first elastic member 14a that is in contact with the contact areas A increases as the distance in the width direction D1 increases. Therefore, when the elastic member 14 is compressed due to the expansion of the battery cell 11a during charging, contact between the extended portion E and the battery cell 11a is suppressed, and as a result, damage to the battery cell 11a is suppressed.

[0033] Furthermore, the corrugated leaf spring W in contact with the contact region A may have an extended portion E that extends outward from the contact region A, which is located at the outermost edge in the width direction D1, toward the outside in the width direction D1.

[0034] As shown in Figure 9, in the corrugated leaf spring W in contact with the contact region A, the length L1 in the width direction D1 between the end of the extended portion E and the top T (or bottom) of the adjacent curved portion C and the end of the extended portion E is greater than the length L2 in the width direction D1 between the bottom B of the adjacent curved portion C and the top T. Therefore, the hysteresis loss of the second elastic member 14b is reduced. In this case, the ratio of L1 to L2 is not particularly limited, but for example, it is between 1 and 2. Also, L1 is not particularly limited, but for example, it is between 5 mm and 20 mm.

[0035] The elastic member 14 is fixed in contact region A, with the first elastic member 14a and the second elastic member 14b. This improves the strength of the elastic member 14. The method for fixing the first elastic member 14a and the second elastic member 14b in contact region A is not particularly limited, but one example is to bond the first elastic member 14a and the second elastic member 14b in contact region A using an elastic adhesive.

[0036] On the other hand, the corrugated leaf spring W in contact with the contact region A has an extended portion E that is not fixed. Also, the corrugated leaf spring W in contact with the contact region A is separated from the adjacent corrugated leaf spring W at its extended portion E. As a result, the hysteresis loss of the second elastic member 14b is reduced. At this time, the distance between the ends of adjacent corrugated leaf springs W in the width direction D is not particularly limited, but for example, it is 0.1 mm or more and 1 mm or less.

[0037] The number of layers of the corrugated leaf springs W is not limited to 4, but can be 2N (where N is a natural number). N is not particularly limited, but for example, it is between 1 and 3. When N is 2 or greater, the corrugated leaf springs W that are not in contact with the contact region A have an extended portion corresponding to the extended portion E of the corrugated leaf springs W that are in contact with the contact region A.

[0038] Furthermore, the bottom and top portions of the opposing curved surfaces C of adjacent corrugated leaf springs W may be bonded together, for example, with an elastic adhesive.

[0039] The Poisson's ratio of the first elastic member 14a is preferably 0.3 or less. When the Poisson's ratio of the first elastic member 14a is 0.3 or less, the first elastic member 14a can more easily absorb the change in thickness due to the expansion and contraction of the battery cell 11a. For example, the Poisson's ratio of the first elastic member 14a is 0 or more.

[0040] The thickness of the first elastic member 14a when the battery cell 11a is at 100% charge is not particularly limited, but is, for example, 0.05 mm or more and 0.1 mm or less.

[0041] The first elastic member 14a is, for example, a foam having a porosity of 30% to 95%. The material constituting the foam is not particularly limited, but examples include polyurethane, silicone resin, ethylene propylene rubber, styrene resin, olefin resin, polyamide, and polyester.

[0042] The Young's modulus of the material constituting the second elastic member 14b is preferably 35 GPa or higher. When the Young's modulus of the material constituting the second elastic member 14b is 35 GPa or higher, the second elastic member 14b is better able to absorb the change in thickness due to the expansion and contraction of the battery cell 11a. For example, the Young's modulus of the material constituting the second elastic member 14b is 200 GPa or less.

[0043] The material constituting the second elastic member 14b is not particularly limited, but examples include metals such as stainless steel and carbon steel, resins such as epoxy resin, phenolic resin, and nylon resin, and fiber-reinforced plastics (FRP) such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP). Among these, FRP is preferred, and GFRP is particularly preferred, considering the energy density of the battery module 10.

[0044] The thickness of the second elastic member 14b when the battery cell 11a is at 100% charge is not particularly limited, but is, for example, 1.0 mm or more and 1.2 mm or less.

[0045] The following describes an example of a method for manufacturing the elastic member 14. First, a first elastic member 14a is obtained by foam molding. Meanwhile, a corrugated leaf spring W is formed by press molding, and then a portion of the four-layered corrugated leaf spring W is bonded with an elastic adhesive to obtain a second elastic member 14b. Next, elastic adhesive G is applied to the bottom of the lower curved portion C of the second elastic member 14b, and then the first elastic member 14a is placed on top (see Figure 10(a)). At this time, pressure may be applied simultaneously with or after placing the first elastic member 14a on the bottom of the lower curved portion C of the second elastic member 14b. Next, elastic adhesive G is applied to the top of the upper curved portion C of the second elastic member 14b, and then the first elastic member 14a is placed on top (see Figure 10(b)). At this time, the first elastic member 14a may be placed on the top of the upper curved portion C of the second elastic member 14b, or pressure may be applied after the first elastic member 14a has been placed on the top of the upper curved portion C of the second elastic member 14b.

[0046] Known methods can be used to manufacture the battery module 10 using the elastic member 14.

[0047] The battery cell 11a is not particularly limited, but examples include solid battery cells such as semi-solid battery cells and all-solid battery cells, and electrolyte battery cells having a negative electrode composite layer containing lithium metal or lithium alloy. The elements other than lithium that constitute the lithium alloy are not particularly limited, but examples include Sn, Ag, Mg, In, Si, and Al. Among these, solid battery cells having a negative electrode composite layer containing lithium metal or lithium alloy are preferred.

[0048] The following describes the case where battery cell 11a is an all-solid-state lithium metal battery cell.

[0049] An all-solid-state lithium metal battery cell, for example, has a positive electrode current collector, a positive electrode composite layer, a solid electrolyte layer, a lithium metal layer, and a negative electrode current collector stacked sequentially.

[0050] The positive electrode current collector is not particularly limited, and examples thereof include aluminum foil.

[0051] The positive electrode composite material layer includes a positive electrode active material, and may further include a solid electrolyte, a conductive aid, a binder, and the like.

[0052] The positive electrode active material is not particularly limited as long as it can occlude and release lithium ions, and examples thereof include LiCoO2, Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 )O 2、 Li(Ni 6 / 10 Co 2 / 10 Mn 2 / 10 )O 2、 Li(Ni 8 / 10 Co 1 / 10 Mn 1 / 10 )O 2、 Li(Ni 0.8 Co 0.15 Al 0.05 )O 2、 Li(Ni 1 / 6 Co 4 / 6 Mn 1 / 6 )O 2、 Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2、 LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide, and sulfur.

[0053] The solid electrolyte constituting the solid electrolyte layer is not particularly limited as long as it is a material capable of conducting lithium ions, and examples thereof include oxide-based electrolytes and sulfide-based electrolytes.

[0054] The negative electrode current collector is not particularly limited, and examples thereof include copper foil.

[0055] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and the above embodiments may be appropriately modified within the scope of the gist of the present invention.

Description of Reference Signs

[0056] 10 Battery Modules 11 Battery cell stack 11a battery cell 12 End Plates 13 Bind Bar 14 Elastic members 14a First elastic member 14b Second elastic member A contact area E extension W-shaped leaf spring F flat part C, C0 curved part B Bottom T top G Elastic Adhesive

Claims

1. A battery cell stack in which multiple battery cells are stacked, A pair of plate-shaped members are provided at both ends of the stacking direction of the battery cell stack, The system comprises elastic members disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped member, The elastic member comprises a pair of first elastic members arranged on both outer sides in the stacking direction of the battery cell stack, and a second elastic member arranged between the pair of first elastic members. The second elastic member is made up of corrugated leaf springs stacked in 2N layers (where N is a natural number) in the stacking direction of the battery cell stack. The aforementioned corrugated leaf spring has a continuous arrangement of curved surfaces having a single radius of curvature via a flat surface, and extends in a predetermined direction. The surface of the flat portion is substantially parallel to the tangent plane at the end of the curved portion that is continuously arranged with the flat portion. The radius of curvature of the curved surface is r [mm], and in the corrugated leaf spring, the radius of curvature of the curved surface is r when curved surfaces having a single radius of curvature are arranged alternately in a continuous manner without passing through the flat surface, without changing the height and the pitch of the curved surface. ０ If we leave it as [mm], then the formula 0.50≦r / r ０ ≦0.90 A battery module that satisfies the requirements.

2. formula 0.60≦r / r ０ ≦0.85 A battery module according to claim 1, satisfying the requirements.

3. formula 0.70≦r / r ０ ≦0.80 A battery module according to claim 2, satisfying the requirements.

4. The second elastic member has multiple contact areas in the width direction that are in contact with the first elastic member. The corrugated leaf spring in contact with the aforementioned contact region has an extended portion that extends outward in the width direction from the outermost contact region in the width direction, The battery module according to any one of claims 1 to 3, wherein the distance in the width direction of the extended portion from the first elastic member in contact with the contact region increases as the distance in the width direction increases from the contact region located at the outermost edge in the width direction.

5. The battery module according to claim 4, wherein the corrugated leaf spring in contact in the contact area has a widthwise length between the top or bottom of the curved surface adjacent to the end of the extended portion and the end of the extended portion that is greater than the widthwise length between the bottom and top of the adjacent curved surface.

6. The battery module according to any one of claims 1 to 3, wherein the corrugated leaf spring comprises fiber-reinforced plastic.

7. The battery module according to any one of claims 1 to 3, wherein the battery cell is a solid-state battery cell.

8. The battery module according to any one of claims 1 to 3, wherein the battery cell comprises a negative electrode composite layer containing lithium metal or a lithium alloy.

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