battery cell

Abstract

To provide a battery cell capable of reducing pressure inside a case quickly by breaking a joint part between a case body and a lid when the pressure inside the case increases.SOLUTION: A battery cell includes an electrode body, an electrolyte, and a case 13 housing the electrode body and the electrolyte. The case 13 includes: a case body 20 having a bottom wall, a peripheral wall 22, and an opening 22a surrounded by the peripheral wall 22 and facing the bottom wall; and a plate-shaped lid 30 joined to the opening 22a by welding to seal the opening 22a. A joint part 50 between the case body 20 and the lid 30 extends in the circumferential direction of the opening 22a. The joint part 50 is provided with a step part 56 located further inside the case 13 in a height direction Z with respect to a general part 55 of the joint part 50.SELECTED DRAWING: Figure 7

Description

Technical Field

[0005] , , , , , , , , , ,

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

Background Art

[0002] Patent Document 1 describes a battery including an outer can, an electrode body, a non-aqueous electrolyte, and a sealing plate. The outer can has a bottom wall, a peripheral wall, and an opening surrounded by the peripheral wall and facing the bottom wall. The electrode body and the non-aqueous electrolyte are accommodated inside the outer can.

[0003] The sealing plate closes the opening of the outer can by being welded to the outer can. A notch is provided in a part of the periphery of the sealing plate. The notch opens to the inner surface of the sealing plate. The part of the sealing plate where the notch is provided is a thin-walled part having a smaller thickness than the main body part of the sealing plate. Therefore, when the pressure inside the battery rises due to overcharging or the like and the outer can and the sealing plate expand, the welded part between the thin-walled part and the outer can is broken, and the gas inside the battery is discharged to the outside.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, when the pressure inside the battery rises and the outer can and the sealing plate expand, the stress acting on the sealing plate increases accordingly. At this time, in the case of the battery described in Patent Document 1, since the notch forming the thin plate part has a shape that opens to the inner surface of the sealing plate, there is a problem that the above stress is unlikely to concentrate on the thin-walled part, that is, the welded part between the thin-walled part and the outer can is unlikely to be broken.

Means for Solving the Problems

[0006] The following describes various embodiments of battery cells that address the above-mentioned problems. [Aspect 1] A battery cell comprising an electrode body, an electrolyte, and a case for housing the electrode body and the electrolyte, wherein the case comprises a case body surrounded by a bottom wall, a peripheral wall, and an opening facing the bottom wall, and a plate-shaped lid welded to the opening to seal the opening, wherein the joint portion between the case body and the lid extends in the circumferential direction of the opening, and when the direction perpendicular to both the direction in which the case body and the lid are aligned via the joint portion and the direction in which the joint portion extends is defined as the orthogonal direction, the joint portion is provided with a stepped portion located on the inside of the case in the orthogonal direction compared to the general portion of the joint portion.

[0007] In this configuration, when the case expands due to an increase in internal pressure, stress concentrates in the stepped portion of the joint that is located on the inside of the case in a direction perpendicular to the general area. As a result, the joint between the case body and the lid is more prone to fracture compared to the conventional configuration in which the notch forming the thin plate portion opens to the inner surface of the sealing plate. Therefore, when the internal pressure of the case rises, the internal pressure can be reduced more quickly by causing the joint between the case body and the lid to fracture.

[0008] [Aspect 2] The stepped portion has a bottom portion that is aligned with the extending direction of the general portion and a connecting portion that connects the bottom portion and the general portion, and the thickness of the bottom portion is smaller than the thickness of the general portion, as described in [Aspect 1] of the battery cell.

[0009] In this configuration, the thickness of the bottom of the stepped section is smaller than the thickness of the general section, so as the pressure inside the case increases, the bottom section deforms preferentially. As a result, stress becomes more concentrated in the stepped section. Consequently, the joint between the case body and the lid becomes more prone to fracture.

[0010] [Aspect 3] The battery cell according to [Aspect 2], wherein the thickness of the connecting portion gradually decreases from the general portion towards the bottom portion.

[0011] With this configuration, the thickness of the connecting section gradually decreases from the general section towards the bottom, causing stress to concentrate more at the connection point between the connecting section and the bottom. Consequently, the joint between the case body and the lid becomes more prone to fracture.

[0012] [Aspect 4] A battery cell according to any one of [Aspect 1] to [Aspect 3], wherein a step is provided in the portion of at least one of the case body and the lid that constitutes the stepped portion, and the step is provided along the stepped portion.

[0013] According to this configuration, the step can be easily created by pre-forming the step in the portion of at least one of the case body and the lid that will constitute the step, and then welding the case body and the lid along the step.

[0014] [Aspect 5] A battery cell according to any one of [Aspect 1] to [Aspect 4], wherein the outer surface of the peripheral wall adjacent to the stepped portion is provided with a rib extending in the direction of extension of the joint portion, the rib has an outer rib surface which is the surface on the lid side, and the portion of the outer rib surface corresponding to the portion where the stepped portion is provided in the direction of extension of the joint portion is provided with a rib stepped portion which is located closer to the bottom wall than the other portion of the outer rib surface, and the distance between the stepped portion and the rib stepped portion is greater than the distance between the general portion and the other portion.

[0015] With this configuration, when the pressure inside the case increases and the case expands, the portion of the case body's peripheral wall between the rib step and the lid expands more easily than other parts. Therefore, when the pressure inside the case increases, the joint between the case body and the lid becomes more prone to fracture.

[0016] [Aspect 6] The battery cell according to [Aspect 5], comprising a flow path component member joined to the outer surface of the peripheral wall and constituting a flow path for a cooling fluid, wherein the rib is a part of the flow path component member.

[0017] In the battery cell, a flow path component member that constitutes a flow path for a cooling fluid is joined to the peripheral wall of the case body. According to the above configuration, since the rib is configured as a part of the flow path component member, the rib can be easily embodied by partially changing the configuration of the existing flow path component member.

[0018] [Aspect 7] In a battery cell including an electrode body, an electrolytic solution, and a case that houses the electrode body and the electrolytic solution, the case includes a case body having a bottom wall, a peripheral wall, and an opening surrounded by the peripheral wall and facing the bottom wall, and a plate-shaped lid body joined to the opening by welding to seal the opening. A joining portion between the case body and the lid body extends in the circumferential direction of the opening, and a rib extending in the extending direction of the joining portion is provided on the outer surface of the peripheral wall. The rib has a rib outer surface portion that is a surface on the lid body side, and a rib step portion located closer to the bottom wall side than other portions on the rib outer surface portion is provided on the rib outer surface portion.

[0019] According to the same configuration, when the pressure inside the case increases and the case expands, a portion between the rib step portion and the lid body in the peripheral wall of the case body is more likely to expand than other portions. Therefore, when the pressure inside the case increases, the pressure inside the case can be reduced early by breaking the joining portion between the case body and the lid body. [Advantages of the Invention]

[0020] According to the present invention, when the pressure inside the case increases, the pressure inside the case can be reduced early by breaking the joining portion between the case body and the lid body. [Brief Description of the Drawings]

[0021] [Figure 1] Figure 1 is a plan view of a battery stack including the battery cell of the first embodiment. [Figure 2] Figure 2 is an exploded perspective view of the battery cell body of Figure 1. [Figure 3] Figure 3 is a side view centered on the lid step portion of the lid of Figure 2. [Figure 4] Figure 4 is a side view of the spacer of Figure 1. [Figure 5] Figure 5 is a cross-sectional view of the battery cell along the line 5-5 of Figure 2. [Figure 6] Figure 6 is a cross-sectional view of the battery cell along the line 6-6 of Figure 2. [Figure 7] Figure 7 is a cross-sectional view of the battery cell along the line 7-7 of Figure 6. [Figure 8] Figure 8 is a view corresponding to Figure 7 and is a cross-sectional view of the battery cell of the second embodiment. [Figure 9] Figure 9 is a view corresponding to Figure 7 and is a cross-sectional view of the battery cell of the first modification. [Figure 10] Figure 10 is a view corresponding to Figure 7 and is a cross-sectional view of the battery cell of the second modification. [Figure 11] Figure 11 is an enlarged plan view of a part of the battery cell of the third modification.

Mode for Carrying Out the Invention

[0022] <First Embodiment> Hereinafter, a first embodiment of the battery cell will be described with reference to FIGS. 1 to 7. As shown in FIG. 1, the battery stack includes a plurality of battery cells 10 arranged in a stacked manner.

[0023] The battery cell 10 includes a battery cell body 10A and a spacer 40 provided adjacent to the battery cell body 10A in the stacking direction of the battery cells 10. The battery cell body 10A is, for example, a lithium ion battery.

[0024] <Battery cell body 10A> As shown in Figure 2, the battery cell body 10A comprises an electrode body 11, an electrolyte 12, and a case 13 that houses the electrode body 11 and the electrolyte 12.

[0025] The electrode body 11 comprises a positive electrode, a negative electrode, and a separator (none of which are shown) provided between the positive electrode and the negative electrode. The electrolyte 12 is, for example, a composition containing a supporting salt in a non-aqueous solvent.

[0026] Case 13 comprises a case body 20 and a lid 30. <Case body 20> As shown in Figure 2, the case body 20 is surrounded by a bottom wall 21, a peripheral wall 22, and an opening 22a facing the bottom wall 21.

[0027] The bottom wall 21 is rectangular in shape. In the following explanation, the long and short sides of the bottom wall 21 will be described as the length direction L and the width direction W, respectively. Furthermore, the direction perpendicular to both the length direction L and the width direction W will be described as the height direction Z.

[0028] Case 13 of this embodiment has a symmetrical structure in the length direction L and a symmetrical structure in the width direction W. Therefore, in the following, we may describe one side of Case 13 in the length direction L and omit the description of the other side. Similarly, we may describe one side of Case 13 in the width direction W and omit the description of the other side.

[0029] The peripheral wall 22 extends in the height direction Z from the periphery of the bottom wall 21 and has an opening 22a. The peripheral wall 22 has a pair of first wall portions 23 extending in the length direction L and a pair of second wall portions 24 extending in the width direction W.

[0030] On the edge 25 of the first wall portion 23 opposite to the bottom wall 21, a pair of case step portions 26 are provided, which are located closer to the bottom wall 21 than the general portion 25a of the edge 25. The case step portion 26 is provided in the central part of the edge 25 in the longitudinal direction L. The case step portion 26 has a bottom portion 27 that extends along the longitudinal direction L, and a pair of connecting portions 28 that connect both ends of the bottom portion 27 in the longitudinal direction L to the general portion 25a, respectively. The connecting portions 28 are inclined such that they move closer to the general portion 25a in the height direction Z as they move away from the bottom portion 27 in the longitudinal direction L.

[0031] The case body 20 is formed from a metal material such as an aluminum alloy. <Lid 30> As shown in Figures 1 and 2, the lid 30 is plate-shaped and is welded to the inner circumferential surface 22b of the opening 22a, sealing the opening 22a. In this embodiment, the lid 30 is a rectangular plate that is long in the length direction L.

[0032] As shown in Figures 5 and 6, the lid 30 is joined to the inner circumferential surface 22b of the opening 22a of the case body 20. As shown in Figures 2, 5, and 6, the lid 30 has an outer surface portion 31 that constitutes the outer surface of the case 13, an inner surface portion 32 that constitutes the inner surface of the case 13, and a peripheral edge portion 35.

[0033] The peripheral edge portion 35 has a pair of first edge portions 35a extending in the longitudinal direction L and a pair of second edge portions 35b extending in the width direction W. The peripheral edge 35 of the lid 30 is joined all around to the inner circumferential surface 22b of the opening 22a by, for example, laser welding.

[0034] As shown in Figures 1 and 2, the outer surface 31 of the lid 30 is provided with a negative external terminal 15 and a positive external terminal 16 used for charging and discharging power. The negative external terminal 15 and the positive external terminal 16 are arranged with a gap between them in the longitudinal direction L.

[0035] The inner surface 32 of the cover 30 is provided with a negative electrode current collector 17 and a positive electrode current collector 18. The negative electrode current collector 17 connects the negative electrode of the electrode body 11 to the negative electrode external terminal 15. The positive electrode current collector 18 connects the positive electrode of the electrode body 11 to the positive electrode external terminal 16.

[0036] A stepped portion 36 is provided on the peripheral edge 35 of the lid 30. The stepped portion 36 of the lid is provided in the central part of the first edge 35a in the longitudinal direction L. Preferably, the stepped portion 36 of the lid is provided on both sides of the first edge 35a.

[0037] The stepped portion 36 of the lid has both its outer surface 31 and inner surface 32 positioned closer to the bottom wall 21 than the main body portion 34 of the lid 30. As shown in Figure 3, the stepped portion 36 of the lid has a bottom portion 37 that is aligned with the surface direction of the main body portion 34, and a connecting portion 38 that connects the bottom portion 37 and the main body portion 34.

[0038] The connecting portion 38 has a pair of first connecting portions 38a and a second connecting portion 38b. The pair of first connecting portions 38a connect both ends of the bottom portion 37 and the main body portion 34 in the longitudinal direction L.

[0039] The second connecting portion 38b connects the inner end of the bottom portion 37 in the width direction W to the main body portion 34. As shown in Figures 6 and 7, the bottom 37 of the lid step portion 36 and the outer surface of the pair of first connecting portions 38a are flush with the outer surface of the case step portion 26 (both the top surface in Figures 6 and 7).

[0040] As shown in Figure 3, the thickness T1 of the bottom portion 37 is smaller than the thickness T2 of the main body portion 34 (T1 <T2)。 The thickness T3 of the first connecting portion 38a gradually decreases as it approaches the bottom portion 37 from the main body portion 34.

[0041] The lid 30 is formed from the same metal material as the case body 20. <Joint part 50> As shown in Figure 7, the joint between the case body 20 and the peripheral edge 35 extends in the circumferential direction of the opening 22a and also has a pair of joint portions 50 that extend in the longitudinal direction L.

[0042] The joint portion 50 has an outer end face 51 which is the end face on the outer surface portion 31 side and an inner end face 52 which is the end face on the inner surface portion 32 side. The joint portion 50 is provided with a stepped portion 56 that extends along the case stepped portion 26 and the lid stepped portion 36.

[0043] The stepped portion 56 is located inside the case 13 in the height direction Z compared to the general portion 55 of the joint portion 50. In this embodiment, both the outer end face 51 and the inner end face 52 of the stepped portion 56 are located closer to the bottom wall 21 than the general portion 55 of the joint portion 50.

[0044] The stepped portion 56 has a bottom portion 57 that is aligned with the extending direction of the general portion 55, and a connecting portion 58 that connects the bottom portion 57 and the general portion 55. The connecting portion 58 connects both ends of the bottom portion 57 in the longitudinal direction L to the general portion 55.

[0045] The thickness T4 of the bottom part 57 is smaller than the thickness T5 of the general part 55 (T4 <T5)。 The thickness T6 of the connecting portion 58 gradually decreases from the general portion 55 towards the bottom portion 57.

[0046] <Spacer 40> As shown in Figures 4 to 6, the spacer 40 comprises a flat base portion 41 and a plurality of ribs 42.

[0047] The base portion 41 has a rectangular parallelepiped shape similar to the first wall portion 23 of the peripheral wall 22, and is positioned opposite the outer surface 22A of the first wall portion 23 with a gap between them. The rib 42 protrudes from one surface 41a of the base 41 toward the first wall 23.

[0048] The tip surface of the rib 42 is joined to the outer surface 22A of the first wall portion 23. The first wall portion 23, the base portion 41, and the multiple ribs 42 define the flow path for the cooling air that cools the battery cell 10.

[0049] As shown in Figure 4, the multiple ribs 42 include a first rib 43 located closest to the lid 30 in the height direction Z, and a second rib 47 located further away from the lid 30 than the first rib 43 in the height direction Z.

[0050] The first rib 43 extends in the longitudinal direction L. The first rib 43 has an outer rib surface portion 44 which is the surface on the lid 30 side in the height direction Z.

[0051] In the outer surface portion 44 of the rib, a rib step portion 46 is provided in the portion corresponding to the portion where a step portion 56 is provided in the longitudinal direction L. The rib step portion 46 is located closer to the bottom wall 21 in the height direction Z than other portions 45 of the rib outer surface portion 44. In this embodiment, the first rib 43 has a constant thickness throughout its entire length in the direction of extension.

[0052] As shown in Figure 7, the distance Z1 between the stepped portion 56 and the rib stepped portion 46 in the height direction Z is greater than the distance Z2 between the general portion 55 and the other portion 45 of the first rib 43 in the height direction Z (Z1 > Z2).

[0053] The first rib 43 corresponds to the rib in the [Problems to be Solved by the Invention] section. The spacer 40 corresponds to the flow path component. The cooling air corresponds to the cooling fluid. The case step portion 26 and the lid step portion 36 correspond to steps. The width direction W corresponds to the alignment direction of the case body 20 and the lid 30 via the joint portion 50. The length direction L corresponds to the extension direction of the joint portion 50. The height direction Z corresponds to the orthogonal direction.

[0054] Next, the effects and advantages of this embodiment will be described. (1-1) A stepped portion 56 is provided at the joint portion 50 between the case body 20 and the peripheral edge portion 35.

[0055] With this configuration, when the pressure inside the case 13 increases and the case 13 expands, stress concentrates on the stepped portion 56 of the joint portion 50, which is located on the inside of the case 13 in the height direction Z, more than on the general portion 55. As a result, the joint portion 50 between the case body 20 and the lid 30 is more prone to fracture compared to the conventional configuration in which the notch forming the thin plate portion opens to the inner surface of the sealing plate. Therefore, when the pressure inside the case 13 increases, the pressure inside the case 13 can be reduced more quickly by causing the joint portion 50 between the case body 20 and the lid 30 to fracture.

[0056] (1-2) Since the thickness T4 of the bottom 57 of the stepped portion 56 is smaller than the thickness T5 of the general portion 55, the bottom 57 deforms preferentially as the pressure inside the case 13 increases. As a result, stress becomes more concentrated in the stepped portion 56. Consequently, the joint portion 50 between the case body 20 and the lid 30 becomes more prone to fracture.

[0057] (1-3) As the thickness T6 of the connecting portion 58 gradually decreases from the general portion 55 towards the bottom portion 57, stress becomes more concentrated at the connection between the connecting portion 58 and the bottom portion 57. Consequently, the joint portion 50 between the case body 20 and the lid 30 becomes more prone to fracture.

[0058] (1-4) The stepped portion 26 of the case and the stepped portion 36 of the lid are provided along the stepped portion 56. With this configuration, the case step portion 26 and the lid step portion 36 are pre-provided in the parts of the case body 20 and the lid 30 that will constitute the stepped portion 56. Furthermore, the stepped portion 56 can be easily created by welding the case body 20 and the lid 30 along the case step portion 26 and the lid step portion 36.

[0059] (1-5) The distance Z1 between the stepped portion 56 and the rib stepped portion 46 is greater than the distance Z2 between the general portion 55 and the other portion 45. With this configuration, when the pressure inside the case 13 increases and the case 13 expands, the portion of the peripheral wall 22 of the case body 20 between the rib step portion 46 and the lid 30 expands more easily than other portions. Therefore, when the pressure inside the case 13 increases, the joint portion 50 between the case body 20 and the lid 30 becomes more prone to fracture.

[0060] (1-6) Since the first rib 43 is configured as part of the spacer 40 which functions as a flow channel component, the first rib 43 can be easily realized by partially modifying the configuration of the existing spacer 40.

[0061] <Second Embodiment> Next, referring to Figure 8, the second embodiment will be described, focusing on the differences from the first embodiment.

[0062] This embodiment differs from the first embodiment in that there is no stepped portion at the joint, no stepped portion on the lid, and no stepped portion on the case body.

[0063] In the following, for configurations of the second embodiment that are the same as or corresponding to those of the first embodiment, redundant explanations may be omitted by adding the code "1**" which is the code "**" of the configuration of the first embodiment plus "100".

[0064] As shown in Figure 8, the outer surface 122A of the peripheral wall 122 is provided with a first rib 143 that extends in the longitudinal direction L. The first rib 143 has an outer rib surface portion 144 which is the surface on the lid 130 side in the height direction Z.

[0065] The outer surface portion 144 of the rib is provided with a rib step portion 146 that is located closer to the bottom wall 121 in the height direction Z than other portions 145 of the outer surface portion 144 of the rib. The distance Z1 between the general part 155 of the joint part 150 and the rib step part 146 in the height direction Z is larger than the distance Z2 between the general part 155 and the other part 145 in the height direction Z (Z1>Z2).

[0066] Next, the operation and effect of this embodiment will be described. (2-1) A rib step part 146 is provided on the rib outer surface part 144. According to such a configuration, when the case 113 expands due to an increase in the pressure inside the case 113, the portion between the rib step part 146 and the lid body 130 of the peripheral wall 122 of the case body 120 is more likely to expand than the other part 145. Therefore, when the pressure inside the case 113 rises, the pressure inside the case 113 can be reduced early by breaking the joint part 150 between the case body 120 and the lid body 130.

[0067] <Modified Example> This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0068] · In each of the above embodiments, the bases 41, 141 of the spacers 40, 140 and the second rib 47 can be omitted, and only the first ribs 43, 143 can be joined to the outer surfaces 22A, 122A of the first wall parts 23, 123. Even in this case, the same effects as the effects (1 - 4) of the first embodiment can be achieved.

[0069] · In the first embodiment, the rib step part 46 can also be omitted. · In the first embodiment, the thickness T3 of the first connecting part 38a gradually decreases as it approaches the bottom part 37 from the main body part 34, but the thickness T3 of the first connecting part 38a may be constant.

[0070] · In the first embodiment, the thickness T1 of the bottom part 37 is made smaller than the thickness T2 of the main body part 34 (T1<T2), but the thickness T1 of the bottom part 37 and the thickness T2 of the main body part 34 may be the same (T1=T2).

[0071] · In the first embodiment, the case body 20 is provided with a case stepped portion 26 and the lid body 30 is provided with a lid body stepped portion 36. However, the present invention is not limited to this. As shown in FIG. 9, in the case body case stepped portion may be omitted while the lid body 230 may be provided with a lid body stepped portion 236. Even in this case, by providing the joint portion 250 along the lid body stepped portion 236, the stepped portion 256 can be provided in the joint portion 250. Further, as shown in FIG. 10, the case body 320 may be provided with a case stepped portion 326 while the lid body stepped portion may be omitted in the lid body 330. Even in this case, by providing the joint portion 350 along the case stepped portion 326, the stepped portion 356 can be provided in the joint portion 350.

[0072] · In the first embodiment, the thickness T6 of the connecting portion 58 is gradually reduced as it approaches the bottom portion 57 from the general portion 55. However, the thickness T6 of the connecting portion 58 may be constant. · In the first embodiment, the thickness T4 of the bottom portion 57 is made smaller than the thickness T5 of the general portion 55 (T4 < T5). However, the thickness T4 of the bottom portion 57 and the thickness T5 of the general portion 55 may be the same (T4 = T5).

[0073] · In each of the above embodiments, the lid body 30 is joined to the inner peripheral surface 22b of the opening 22a by welding. However, the present invention is not limited to this. As shown in FIG. 11, in a state where the lid body 430 is disposed on the upper surface of the edge 425 of the case body 420, the lid body 430 and the case body 420 may be joined by welding. In this case, in the welded portion 450, the stepped portion 456 can be provided so as to be located inside the case 413 in the width direction W from the general portion 455. Even in this case, the same effects as the effect (1-1) of the first embodiment can be achieved.

Explanation of Reference Numerals

[0074] 10… Battery cell 10A… Battery cell body 11… Electrode body 12… Electrolyte 13,113,413... cases 15…Negative external terminal 16…Positive external terminal 17...Negative electrode current collector 18...Positive electrode current collector 20, 120, 220, 320, 420… Case body 21,121...Bottom wall 22,122…peripheral wall 22A, 122A…External surface 22a...Opening 22b…Inner peripheral surface 23…First wall part 24…Second wall part 25,425…edge 25a…General section 26,326...Case step section 27...bottom 28...Connection part 30, 130, 230, 330, 430… Lid 31…External part 32...Inner part 34...Main body 35,135... Peripheral area 35a...first edge 35b…Second edge 36,236... Stepped section of the lid 37...bottom 38...Connection part 38a...1st connection part 38b…Second connection part 40,140…spacer 41,141...Base 41a... one side 42... Rib 43,143…1st Rib 44,144… Rib outer surface 45,145...other parts 46,146... Rib step section 47…2nd rib 50,150,250,350,450...joint part 51…Outer end face 52...Inner end surface 55,155,455…General section 56,256,356,456... Stepped section 57…bottom 58…Connecting Section

Claims

1. A battery cell comprising an electrode body, an electrolyte, and a case for housing the electrode body and the electrolyte, The case comprises a rectangular parallelepiped case body surrounded by a bottom wall, a periphery wall, and the periphery wall, and having a rectangular opening at the top facing the bottom wall, and a plate-shaped lid that is welded to the opening and seals the opening. The case body and the lid are joined at the joint portion of the periphery of the opening. When the longitudinal direction of the opening of the case body is defined as the length direction L, the width direction of the opening perpendicular to the length direction L is defined as the width direction W, and the height direction perpendicular to the length direction L and the width direction W is defined as the height direction Z, The joint portion between the case body and the lid is provided with a general portion along the length L of the rectangular opening and a stepped portion located inside the case in the height Z direction, relative to the general portion. Battery cell.

2. The stepped portion has a bottom portion parallel to the length L of the general portion and a connecting portion that connects the bottom portion and the general portion. The thickness of the bottom portion is smaller than the thickness of the general portion. The battery cell according to claim 1.

3. The thickness of the connecting portion gradually decreases from the general portion towards the bottom portion. The battery cell according to claim 2.

4. A step is provided in the portion of at least one of the case body and the lid that constitutes the stepped portion. The aforementioned step is provided along the stepped portion, The battery cell according to claim 1.

5. The outer surface of the portion of the peripheral wall adjacent to the stepped portion is provided with ribs extending in the longitudinal direction L of the joint portion. The rib has an outer surface portion which is the surface on the lid side, In the outer surface of the rib, the portion corresponding to the portion where the stepped portion is provided in the longitudinal direction L of the joint portion is provided, and the rib stepped portion is located closer to the bottom wall than the other portions of the outer surface of the rib. The distance between the stepped portion and the rib stepped portion is greater than the distance between the general portion and the other portion. The battery cell according to claim 1.

6. The peripheral wall is joined to the outer surface and comprises a flow channel component that constitutes a flow channel for cooling fluid, The rib is part of the flow channel component. The battery cell according to claim 5.

7. A battery cell comprising an electrode body, an electrolyte, and a case for housing the electrode body and the electrolyte, The case comprises a rectangular parallelepiped case body surrounded by a bottom wall, a periphery wall, and the periphery wall, and having a rectangular opening at the top facing the bottom wall, and a plate-shaped lid that is welded to the opening and seals the opening. The case body and the lid are joined at the joint portion of the periphery of the opening. The outer surface of the peripheral wall is provided with ribs parallel to the longitudinal direction L, which is the longitudinal direction of the opening of the case body. The rib has an outer surface portion which is the surface on the lid side, The outer surface of the rib is provided with a rib step portion that is located closer to the bottom wall than other parts of the outer surface of the rib. Battery cell.

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