Battery

Abstract

To solve a problem in which a current path is easily interrupted when the temperature inside the battery case becomes high.SOLUTION: A battery includes a battery case 70, an electrode body 30 provided within the battery case, a negative terminal 22 connected to the electrode body within the battery case, and a positive terminal connected to the electrode body within the battery case, and a part of a target terminal, which is at least one of the negative terminal and the positive terminal, is a storage portion 22D located within the battery case and separated from the electrode body, and a gas generating agent that gasifies when the temperature reaches or exceeds a predetermined temperature is provided inside the storage portion.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a battery. [Background technology]

[0002] The following Patent Document 1 discloses a battery in which a thermal expansion material is disposed at the joint between the electrode body and the current collecting terminal. When this battery is overcharged or an internal short circuit occurs, the temperature inside the battery case rises. When the temperature inside the battery case rises, the thermal expansion material thermally expands, which causes the joint to break. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-130320 A Summary of the Invention [Problem to be solved by the invention]

[0004] The thermal expansion material is provided in a narrow space inside the battery case and is sandwiched between the electrode body and the current collecting terminal. Therefore, if the joint breaks, the electrode body and the current collecting terminal may not be completely separated. In other words, there is a risk that the electrode body and the current collecting terminal may not be electrically disconnected.

[0005] In consideration of the above, an object of the present invention is to provide a battery in which the current path is easily interrupted when the temperature inside the battery case becomes high. [Means for solving the problem]

[0006] A battery of a first aspect of the present invention comprises a battery case, an electrode body provided in the battery case, a negative electrode terminal partially located within the battery case and connected to the electrode body within the battery case, a positive electrode terminal partially located within the battery case and connected to the electrode body within the battery case, a storage section provided in a portion of a target terminal which is at least one of the negative electrode terminal and the positive electrode terminal and separated from the electrode body within the battery case, and a gas generating agent provided inside the storage section and gasified when the temperature reaches or exceeds a predetermined temperature.

[0007] In a battery according to a second aspect of the present invention, in the battery according to the first aspect of the present invention, the storage section includes a fragile portion to which force is applied from the gasified gas generating agent.

[0008] In a battery according to a third aspect of the present invention, in the battery according to the first or second aspect of the present invention, the fragile portion is a portion adjacent to a cut provided on the outer surface of the storage portion.

[0009] In the battery according to the fourth aspect of the present invention, when the storage section receives heat from the periphery of the target terminal, the temperature of the storage section is likely to become higher than that of the surrounding area of ​​the target terminal of the storage section.

[0010] In a fifth aspect of the battery of the present invention, the target terminal comprises a linear first component portion, a second component portion connected to the electrode body and parallel to the first component portion, and the storage portion connects an end portion of the first component portion on the second component portion side to an end portion of the second component portion on the first component portion side, and is inclined with respect to the first component portion and the second component portion. Effect of the Invention

[0011] In the battery of the first aspect of the present invention, a gas generating agent is provided inside the storage section of the target terminal, which is at least one of the negative and positive terminals. For example, when the storage section of the target terminal becomes hot due to overcharging or an internal short circuit, the gas generating agent may reach a temperature equal to or higher than a predetermined temperature. In this case, the gas generating agent gasifies and exerts pressure on the storage section, causing the storage section to break. The storage section is separated from the electrode body. Therefore, after the storage section breaks, it is unlikely that the two separated parts of the storage section will maintain contact with each other. Therefore, in the battery of the first aspect, the current path is easily interrupted when the temperature inside the battery case becomes high.

[0012] In the battery according to the second aspect of the present invention, the weak portion of the housing portion is prone to breakage when the gas generating agent is gasified.

[0013] In the battery according to the third aspect of the present invention, a cut is provided on the outer surface of the storage section, and the fragile portion is adjacent to the cut, so that the fragile portion is easily broken when the gas generating agent is gasified.

[0014] When the battery case of the fourth aspect of the present invention receives heat from the surroundings of the target terminal, the storage section of the battery of the fourth aspect of the present invention is more likely to become hotter than the surrounding area of ​​the storage section of the target terminal, and therefore the current path of the battery of the fourth aspect is more likely to be interrupted when the temperature inside the battery case becomes high.

[0015] In the battery according to the fifth aspect of the present invention, gas generated within the battery case is likely to be present around the storage section, and therefore the storage section is likely to become hot when, for example, overcharging or an internal short circuit occurs. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a front view showing a lithium ion secondary battery according to an embodiment. [Diagram 2] FIG. 1 is an exploded perspective view of a lithium-ion secondary battery according to an embodiment. [Diagram 3] 3 is a perspective view showing the wound body cut along the arrow line 3-3 in FIG. 2. [Figure 4] 4 is a schematic cross-sectional view of the wound body taken along the arrow line 4-4 in FIG. 3. [Diagram 5] FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. [Figure 6] 4 is a schematic enlarged view of a portion of a negative electrode current collector of a wound body and a negative electrode current collector terminal. FIG. [Figure 7] FIG. 4 is a schematic enlarged perspective view of a storage portion for a negative electrode current collector terminal. [Figure 8] 7 is an enlarged view similar to FIG. 6, but showing the storage section broken. [Figure 9] FIG. 8 is an enlarged perspective view of a modified example, which corresponds to FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a battery according to an embodiment will be described with reference to the drawings. The battery according to the embodiment is a lithium ion secondary battery as a cell battery constituting a battery module used as an on-board power source for, for example, an electric vehicle, a hybrid vehicle, etc. In each drawing, an arrow D indicates the longitudinal direction D of the lithium ion secondary battery 10, an arrow E indicates the depth direction E of the lithium ion secondary battery 10, and an arrow F indicates the up-down direction F of the lithium ion secondary battery 10.

[0018] [Configuration of lithium-ion secondary battery 10] As shown in FIGS. 1 and 2, a lithium ion secondary battery (battery) 10 includes a lid assembly 20, a wound body 30, and a battery case 70.

[0019] (battery case 70) The battery case 70 is made of, for example, aluminum, and is formed in the shape of a rectangular box that is long in the longitudinal direction D and has an open top.

[0020] (Lid Assembly 20) The lid assembly 20 includes a lid member 21, a negative electrode collector terminal (negative electrode terminal) (target terminal) 22 as a collector terminal, a positive electrode collector terminal (positive electrode terminal) 23 as a collector terminal, a negative electrode external terminal (negative electrode terminal) 24 as an external terminal, and a positive electrode external terminal (positive electrode terminal) 25 as an external terminal.

[0021] <Cover member 21> The lid member 21 is made of, for example, aluminum, and is formed in a rectangular plate shape extending in the longitudinal direction D. The lid member 21 is provided with a safety valve 21A and a cap 26 that closes the injection port 21B.

[0022] The safety valve 21A opens when the internal pressure of the battery case 70 reaches a predetermined pressure, and discharges gas generated inside the battery case 70.

[0023] Injection port 21B is a through-hole that penetrates lid member 21 in the plate thickness direction. Injection port 21B is used when injecting electrolyte 72 (see FIG. 5) into battery case 70. Cap 26 is attached to injection port 21B, for example, by laser welding, and is hermetically sealed.

[0024] With the wound body 30, the negative electrode current collector terminal 22, and the positive electrode current collector terminal 23 housed inside the battery case 70, the lid member 21 is attached, for example, by laser welding, so as to close the opening of the battery case 70. The battery case 70 is filled with an electrolyte 72.

[0025] <Negative electrode current collector terminal 22 and negative electrode external terminal 24> The negative electrode current collector terminal 22 and the negative electrode external terminal 24 are formed of, for example, copper, and are disposed on the other end side in the longitudinal direction D inside the battery case 70. The negative electrode current collector terminal 22 is a member extending in the vertical direction. As shown in FIG. 2 and FIG. 5, the negative electrode current collector terminal 22 includes an upper end portion 22A constituting the upper end portion of the negative electrode current collector terminal 22, an intermediate portion (first component portion) 22B extending downward from the upper end portion 22A, a lower end portion (second component portion) 22C connected to the negative electrode current collector portion 32 of the wound body 30 and located below the lower end of the intermediate portion 22B, and a storage portion 22D connecting the lower end portion of the intermediate portion 22B and the upper end portion of the lower end portion 22C. When viewed along the longitudinal direction D as shown in FIG. 5, the intermediate portion 22B and the lower end portion 22C extend linearly in a direction substantially parallel to the vertical direction, and the storage portion 22D is inclined with respect to the intermediate portion 22B and the lower end portion 22C. The upper end portion 22A is electrically connected to the negative electrode external terminal 24. The negative electrode external terminal 24 is exposed to the outside of the lid member 21.

[0026] 6 and 7, a recess (internal space) 22D1 is provided on the surface of the storage section 22D. Furthermore, a gas generating agent 27 is provided in the recess 22D1. The gas generating agent 27 is, for example, ethanol, acetonitrile, or 2-methyl-2-propanol. The opening of the recess 22D1 is closed by a lid 22D2 having substantially the same shape as the opening. Furthermore, the gap between the inner peripheral edge of the opening of the recess 22D1 and the outer peripheral edge of the lid 22D2 is airtightly sealed by an adhesive (sealing member).

[0027] Furthermore, cuts 22D3 are provided on the upper and lower surfaces of the storage section 22D. The area between the upper and lower cuts 22D3 in the storage section 22D is a weak portion 22D4. That is, the weak portion 22D4 is adjacent to the upper and lower cuts 22D3. The mechanical strength of the weak portion 22D4 is smaller than the mechanical strength of the negative electrode current collector terminal 22 at the portions other than the weak portion 22D4.

[0028] <Positive electrode current collector terminal 23 and positive electrode external terminal 25> The positive electrode current collector terminal 23 and the positive electrode external terminal 25 are formed of, for example, aluminum, and are disposed at one end of the interior of the battery case 70 in the longitudinal direction D. The positive electrode current collector terminal 23 is formed in a rectangular plate shape with the plate thickness direction being the depth direction E. The positive electrode external terminal 25 is electrically connected to the positive electrode current collector terminal 23, and is exposed to the outside of the lid member 21.

[0029] (Wound body 30) As shown in FIG. 2 and FIG. 3, the wound body (electrode body) 30 has a power generating body 31, a negative electrode current collecting portion 32, and a positive electrode current collecting portion 33.

[0030] The wound body 30 is formed in a flat shape by winding a negative electrode sheet 40 as an electrode sheet, a positive electrode sheet 50 as an electrode sheet, and two separators 60 in a stacked state.

[0031] The power generating body 31 is formed by stacking a region of the positive electrode sheet 50 coated with a positive electrode active material, a region of the negative electrode sheet 40 coated with a negative electrode active material, and a separator 60. The power generating body 31 has a function of storing electric energy of the lithium ion secondary battery 10.

[0032] The negative electrode current collecting part 32 is not coated with an active material, and is formed by winding a negative electrode sheet 40. The positive electrode current collecting part 33 is not coated with an active material, and is formed by winding a positive electrode sheet 50.

[0033] <Negative electrode sheet 40> 4, a negative electrode active material 42 is applied to both sides of a long strip-shaped negative electrode body 41 of a negative electrode sheet 40. The negative electrode active material 42 has an outer periphery-side negative electrode active material 42A arranged on the outer periphery side and an inner periphery-side negative electrode active material 42B arranged on the inner periphery side.

[0034] The other end of the negative electrode body 41 in the width direction G is not coated with the negative electrode active material 42, and the other end of the negative electrode body 41 is exposed.

[0035] <Positive electrode sheet 50> A positive electrode active material 52 is applied to both sides of a long strip-shaped positive electrode body 51 of the positive electrode sheet 50. The positive electrode active material 52 has an outer periphery-side positive electrode active material 52A arranged on the outer periphery side, and an inner periphery-side positive electrode active material 52B arranged on the inner periphery side.

[0036] One end of the positive electrode body 51 in the width direction G is not coated with the positive electrode active material 52, and the one end of the positive electrode body 51 is exposed.

[0037] <Separator 60> The separator 60 is formed of an insulating material such as polypropylene, polyethylene, etc. The separator 60 is disposed between the positive electrode sheet 50 and the negative electrode sheet 40, and insulates the positive electrode sheet 50 from the negative electrode sheet 40.

[0038] The separator 60 is provided so as to protrude from one side in the width direction G relative to the negative electrode sheet 40. The separator 60 is provided so as to be in contact with an edge portion 40A formed at one end portion in the width direction G of the negative electrode sheet 40. The separator 60 is provided so as to protrude from the other side in the width direction G relative to the positive electrode sheet 50.

[0039] As shown in Fig. 5, the wound body 30 is housed inside a battery case 70. The lower end 22C of the negative electrode current collector terminal 22 is joined to a central portion 32M in the up-down direction F of the negative electrode current collector 32 of the wound body 30, for example, by ultrasonic welding. As is clear from Fig. 5, the dimension in the depth direction E of the central portion 32M is smaller than the dimension in the depth direction E of the peripheral portion of the central portion 32M in the wound body 30. Furthermore, the intermediate portion 22B and the storage portion 22D are spaced apart from the negative electrode current collector 32 in the depth direction E (front side). Moreover, the positive electrode current collector terminal 23 is joined to the positive electrode current collector 33 of the wound body 30, for example, by resistance welding.

[0040] (Action and Effects) Next, the operation and effects of this embodiment will be described.

[0041] The output of the wound body 30 of the lithium ion secondary battery 10 configured as described above is taken from the negative electrode external terminal 24 and the positive electrode external terminal 25, and is supplied to an electric motor of a battery electric vehicle or a hybrid electric vehicle (HEV).

[0042] For example, when an internal short circuit occurs in the lithium ion secondary battery 10, the temperature inside the lithium ion secondary battery 10 rises, and gas is generated in the battery case 70 due to the internal short circuit, and this gas is mixed into the electrolyte 72. As shown in FIG. 5, a relatively large area (gap) 70A1 is formed between the negative electrode current collector 32 (center portion 32M) of the wound body 30 and the upper surface of the storage portion 22D, and a relatively large area (gap) 70A2 is formed immediately below the lower surface of the storage portion 22D. Therefore, the gas generated in the battery case 70 is likely to collect in the area 70A1 and the area 70A2. Since the specific heat of this gas is smaller than the specific heat of the electrolyte 72, the areas 70A1 and 70A2 are likely to become hotter than the areas of the electrolyte 72 other than the areas 70A1 and 70A2. Therefore, the storage portion 22D adjacent to the areas 70A1 and 70A2 is particularly likely to become hotter among the negative electrode current collector terminals 22. When the temperature of the storage section 22D rises and the temperature in the recess 22D1 reaches a temperature equal to or higher than the boiling point of the gas generating agent 27 (a temperature equal to or higher than a predetermined temperature), the gas generating agent 27, which was liquid or solid up until that point, turns into a gas, and the air pressure in the recess 22D1 rises rapidly. Therefore, the pressure in the recess 22D1 is applied to the storage section 22D including the fragile portion 22D4, and cracks are generated in the fragile portion 22D4 starting from the upper and lower cuts 22D3. The cracks further spread throughout the fragile portion 22D4, and the fragile portion 22D4 eventually breaks as shown in FIG. 8. The storage section 22D provided with the cuts 22D3 (fragile portion 22D4) in this way is more likely to break when the gas generating agent 27 gasifies than a storage section 22D without the cuts 22D3 (fragile portion 22D4).

[0043] At this time, as shown in Fig. 8, the storage section 22D is separated into two parts, the upper constituent part 22D5 and the lower constituent part 22D6. Furthermore, since the pressure in the recess 22D1 is applied to the storage section 22D, the upper constituent part 22D5 is pushed upward (see arrow UP) and the lower constituent part 22D6 is pushed downward (see arrow DW). Therefore, after the storage section 22D is separated into the upper constituent part 22D5 and the lower constituent part 22D6, there is little possibility that the upper constituent part 22D5 and the lower constituent part 22D6 will come into contact with each other. In other words, there is little possibility that the contact state between the upper constituent part 22D5 and the lower constituent part 22D6 will be maintained. Therefore, the current path in the lithium ion secondary battery 10 is easily and reliably interrupted.

[0044] Although the battery according to the embodiment has been described above, the design of the battery can be appropriately modified without departing from the gist of the present invention.

[0045] The positive current collector terminal 23 may have a portion corresponding to the middle portion 22B, the lower end portion 22C, and the storage portion 22D, and the gas generating agent 27 may be provided in a recess 22D1 provided in the portion corresponding to the storage portion 22D. Alternatively, the negative current collector terminal 22 and the positive current collector terminal 23 may have a portion corresponding to the storage portion 22D, and the gas generating agent 27 may be provided inside the storage portion 22D. When the portion corresponding to the storage portion 22D is provided in either the negative current collector terminal 22 or the positive current collector terminal 23, it is preferable that a cut 22D3 (weak portion 22D4) is provided in the portion corresponding to the storage portion 22D.

[0046] When a portion corresponding to the storage portion 22D is provided in either the negative collector terminal 22 or the positive collector terminal 23, an annular groove 22D7 may be formed in the outer circumferential surface of the storage portion 22D, as shown in Fig. 9. In this case, the periphery of the annular groove 22D7 in the portion corresponding to the storage portion 22D constitutes a weakened portion.

[0047] In the embodiment, the electrode body to which the negative electrode collector terminal 22 and the positive electrode collector terminal 23 are connected within the battery case 70 is constituted by the wound body 30, but a laminated type electrode body may be provided within the battery case 70, and the negative electrode collector terminal 22 and the positive electrode collector terminal 23 may be connected to this electrode body. [Explanation of symbols]

[0048] 10 Lithium-ion secondary battery (battery) 22 Negative current collecting terminal (negative terminal) (target terminal) 22B Middle part (1st component) 22C Lower end (second component) 22D Storage area 22D1 Recess (internal space) 22D3 Cut 22D4 Weak part 23 Positive collector terminal (positive terminal) 24 Negative external terminal (negative terminal) 25 Positive external terminal (positive terminal) 27 Gas Generator 30 Wound body (electrode body) 70 Battery case

Claims

1. A battery case; An electrode body provided in the battery case; a negative electrode terminal a portion of which is located within the battery case and connected to the electrode assembly within the battery case; a positive electrode terminal a portion of which is located within the battery case and which is connected to the electrode assembly within the battery case; a storage portion provided in a part of a target terminal which is at least one of the negative electrode terminal and the positive electrode terminal and which is separated from the electrode body within the battery case; a gas generating agent provided inside the storage portion and gasifying when the temperature reaches or exceeds a predetermined temperature; A battery comprising:

2. The battery according to claim 1 , wherein the storage section has a weak portion to which a force is applied from the gasified gas generating agent.

3. The battery according to claim 2 , wherein the fragile portion is a portion adjacent to a cut provided on the outer surface of the storage portion.

4. 3. The battery according to claim 1, wherein the storage section is more likely to become hotter than a peripheral portion of the storage section in the target terminal when the storage section receives heat from the surroundings of the target terminal.

5. The target terminal is A linear first component portion; a second component connected to the electrode body and parallel to the first component; the storage section connects an end of the first component section on the second component section side and an end of the second component section on the first component section side, and is inclined with respect to the first component section and the second component section; 10. The battery of claim 1 , comprising:

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