Battery cell

Abstract

To provide a battery cell in which release of gas at the time of discharging or charging can be suppressed while an electrode body is being restrained.SOLUTION: A battery cell 20 includes: a long electrode body 19 formed by laminating a positive electrode, a negative electrode, and a separator; band-like tapes 30, 32, 34, 36, 38 extending in a shorter direction of the electrode body 19 and wound around the electrode body 19; and a laminate film for sealing the electrode body 19 with the tapes 30, 32, 34, 36, and 38 wound therearound, while storing the electrode body 19. In a part of the adhesive surface of the tapes 30, 32, 34, 36, and 38 which adheres to the electrode body 19, recessed parts 30A, 32A, 34A, 36A, 38A, which are more recessed than the other parts, are provided.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a battery module in which an electrode assembly is housed in a case. Further, by surrounding the outside of the electrode assembly (electrode body) with a heat-shrinkable protective layer, a structure is formed that suppresses the thermal expansion of the electrode assembly.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in the structure of Patent Document 1 above, by winding a tape or the like around the outer periphery of the electrode body, the electrode body can be restrained. On the other hand, by winding a heat-shrinkable protective layer or the like around the outer peripheral side of the battery cell, there is a possibility that the gas generated during charge and discharge becomes difficult to escape.

[0005] In consideration of the above facts, an object of the present invention is to obtain a battery cell that can suppress the escape of gas during charge and discharge while restraining the electrode body.

Means for Solving the Problems

[0006] The battery cell according to claim 1 includes a long electrode body formed by laminating a positive electrode, a negative electrode, and a separator, a belt-like tape extending in the short direction of the electrode body and wound around the outer periphery of the electrode body, and a laminate film that seals the electrode body around which the tape is wound. A concave portion that is recessed more than other portions is provided in a part of the adhesive surface of the tape that adheres to the electrode body.

[0007] In the battery cell according to claim 1, the electrode body is formed in a long shape by laminating a positive electrode, a negative electrode, and a separator. Further, the tape is formed in a strip shape, extends in the short side direction of the electrode body, and is wound around the outer periphery of the electrode body. Furthermore, the electrode body around which the tape is wound is sealed in a state of being accommodated in a laminate film. In this way, by winding the tape around the outer periphery of the electrode body, the electrode body can be restrained, and the displacement of the laminated electrodes can be suppressed.

[0008] Also, a concave portion that is recessed more than other portions is provided in a part of the adhesive surface of the tape that adheres to the electrode body. As a result, in the concave portion, the restraining force of the electrode body is weaker than that of other portions, so that the gas generated in the electrode body can be discharged without being trapped inside.

[0009] The battery cell according to claim 2 is, in claim 1, wherein the concave portion is separated from the surface of the electrode body in a no-load state.

[0010] In the battery cell according to claim 2, since the concave portion of the tape is separated from the surface of the electrode body in a no-load state, the gas inside the electrode body can move freely in this portion. Here, the "no-load state" is a concept that widely includes a state excluding a state in which the electrode body is expanded by the gas generated inside the electrode body, and does not refer only to a state in which no external force is applied to the electrode body and the tape.

[0011] The battery cell according to claim 3 is, in claim 2, wherein a plurality of the tapes are provided at intervals in the longitudinal direction of the electrode body.

[0012] In the battery cell according to claim 3, since a plurality of tapes are provided at intervals in the longitudinal direction of the electrode body, even in the case of a long electrode body, the displacement of the laminated electrodes can be effectively suppressed.

[0013] The battery cell according to claim 4 is, in claim 3, wherein at least one of the plurality of tapes is provided at a central portion in the longitudinal direction of the electrode body.

[0014] In the battery cell according to claim 4, by providing a tape at the central portion in the longitudinal direction of the electrode body that expands the most thermally, the thermal expansion of the battery cell can be suppressed.

[0015] The battery cell according to claim 5 is, in claim 4, wherein a plurality of the recesses are provided, and at least a part of the recesses in the adjacent tapes as viewed from the longitudinal direction of the electrode body overlap.

[0016] In the battery cell according to claim 5, at least a part of the recesses in the adjacent tapes as viewed from the longitudinal direction of the electrode body overlap. Thereby, the gas generated in the central portion of the electrode body can easily escape in the longitudinal direction.

Effect of the Invention

[0017] As described above, according to the battery cell of the present invention, while restraining the electrode body, it is possible to suppress the escape of gas during charge and discharge.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0019] The battery module 11 including the battery cell 20 according to the embodiment will be described with reference to the drawings.

[0020] (Overall configuration of vehicle 100) FIG. 1 is a schematic plan view showing a main part of a vehicle 100 to which a battery pack 10 having a battery module 11 according to the present embodiment is applied. As shown in FIG. 1, the vehicle 100 is a battery electric vehicle (BEV) having the battery pack 10 mounted under the floor. In addition, in each figure, an arrow UP, an arrow FR, and an arrow LH indicate the upper side in the vehicle vertical direction, the front side in the vehicle longitudinal direction, and the left side in the vehicle width direction, respectively. When explaining using the front-rear, left-right, and up-down directions of the vehicle, unless otherwise specified, the front and rear in the vehicle longitudinal direction, the left and right in the vehicle width direction, and the up and down in the vehicle vertical direction are shown.

[0021] As an example, in the vehicle 100 of the present embodiment, a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 are arranged on the vehicle front side of the battery pack 10. Further, on the vehicle rear side of the battery pack 10, a motor 108, a gearbox 110, an inverter 112, and a charger 114 are arranged.

[0022] The direct current output from the battery pack 10 is supplied to the electric compressor 104, the PTC heater 106, the inverter 112, etc. after the voltage is adjusted by the DC / DC converter 102. Further, by supplying power to the motor 108 via the inverter 112, the rear wheels rotate to make the vehicle 100 run.

[0023] A charging port 116 is provided on the right side part at the rear of the vehicle 100. By connecting a charging plug of an external charging facility (not shown) from the charging port 116, power can be stored in the battery pack 10 via the in-vehicle charger 114.

[0024] Note that the arrangement and structure of each component constituting the vehicle 100 are not limited to the above-described configuration. For example, it may be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. In the present embodiment, the vehicle is a rear-wheel drive vehicle with the motor 108 mounted at the rear of the vehicle, but it is not limited thereto, and it may be a front-wheel drive vehicle with the motor 108 mounted at the front of the vehicle, or a pair of motors 108 may be mounted at the front and rear of the vehicle. Furthermore, a vehicle equipped with in-wheel motors for each wheel may also be used.

[0025] Here, the battery pack 10 is configured to include a plurality of battery modules 11. In the present embodiment, as an example, 10 battery modules 11 are provided. Specifically, five battery modules 11 are arranged in the vehicle front-rear direction on the right side of the vehicle 100, and five battery modules 11 are arranged in the vehicle front-rear direction on the left side of the vehicle 100. Each of the battery modules 11 is electrically connected.

[0026] FIG. 2 is a schematic perspective view of the battery module 11. As shown in FIG. 2, the battery module 11 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. The case 13 of the battery module 11 is formed of an aluminum alloy. For example, the case 13 of the battery module 11 is formed by joining aluminum die casts to both ends of an extruded material of an aluminum alloy by laser welding or the like.

[0027] A pair of voltage terminals 12 and connectors 14 are provided at both ends in the vehicle width direction of the battery module 11. A flexible printed circuit board 21 described later is connected to the connector 14. Also, bus bars (not shown) are welded to both ends in the vehicle width direction of the battery module 11.

[0028] The vehicle-width direction length MW of the battery module 11 is, for example, 350 mm to 600 mm, the vehicle-longitudinal direction length ML is, for example, 150 mm to 250 mm, and the vehicle-vertical direction height MH is, for example, 80 mm to 110 mm.

[0029] FIG. 3 is a plan view of the battery module 11 with the upper lid removed. As shown in FIG. 3, inside the battery module 11, a battery cell group in which a plurality of battery cells 20 are arranged is accommodated. In this embodiment, as an example, 24 battery cells 20 are arranged in the vehicle longitudinal direction and adhered to each other.

[0030] On the battery cell 20, a flexible printed circuit (FPC) 21 is disposed. The flexible printed circuit board 21 is formed in a strip shape with the vehicle width direction as the longitudinal direction, and thermistors 23 are provided at both ends of the flexible printed circuit board 21, respectively. The thermistor 23 is not adhered to the battery cell 20 and is configured to be pressed toward the battery cell 20 side by the upper lid of the battery module 11.

[0031] Also, inside the battery module 11, one or more buffer plates (not shown) are accommodated. For example, the buffer plate is a thin plate-like member that can be elastically deformed, and is disposed between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, buffer materials are disposed at both longitudinal ends and the central portion in the longitudinal direction of the battery module 11, respectively.

[0032] FIG. 4 is a schematic view of the battery cell 20 accommodated in the battery module 11 as viewed from the thickness direction. As shown in FIG. 4, the battery cell 20 is formed in a substantially rectangular plate shape, and a long electrode body 19 is accommodated inside. The electrode body 19 is formed by laminating a positive electrode, a negative electrode, and a separator, and is sealed with a laminate film 22.

[0033] In this embodiment, as an example, the accommodating portion of the electrode body 19 is formed by folding and bonding an embossed sheet-like laminate film 22. Note that both a single cup embossing structure with one embossing process and a double cup embossing structure with two embossing processes can be adopted. In this embodiment, a single cup embossing structure with a drawing depth of about 8 mm to 10 mm is used.

[0034] The upper ends at both longitudinal ends of the battery cell 20 are bent, and the corners form the outer shape. Also, the upper end portion of the battery cell 20 is bent, and a fixing tape 24 is wound along the longitudinal direction at the upper end portion of the battery cell 20.

[0035] Here, terminals (tabs) 26 are provided at both longitudinal ends of the battery cell 20. In this embodiment, as an example, the terminal 26 is provided at a position offset downward from the center in the vertical direction of the battery cell 20. The terminal 26 is joined to a bus bar (not shown) by laser welding or the like.

[0036] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, the length CW2 of the region in which the electrode body 19 is accommodated is, for example, 500 mm to 520 mm, and the height CH of the battery cell 20 is, for example, 80 mm to 110 mm. Therefore, the battery cell 20 is formed in a long shape, and the directions of the lengths CW1 and CW2 are the longitudinal directions.

[0037] Also, the thickness of the battery cell 20 is 7.0 mm to 9.0 mm, and the height TH of the terminal 26 is 40 mm to 50 mm.

[0038] FIG. 5 is a schematic view of the electrode body 19 according to the embodiment as viewed from the thickness direction. As shown in FIG. 5, the electrode body 19 of this embodiment is formed in a long shape by laminating a positive electrode, a negative electrode, and a separator.

[0039] The positive electrode, negative electrode, and separator, although not shown in the figure, have a structure used in a general secondary battery. For example, the negative electrode includes a current collector formed of a metal foil such as a copper foil and a negative electrode active material held by the current collector. The negative electrode active material occludes lithium ions, which are charge carriers, from the non-aqueous electrolyte during charging and discharges them into the non-aqueous electrolyte. The negative electrode active material of the present embodiment uses a material containing silicon such as a silicon-based carbon composite material, but is not limited thereto. For example, known negative electrode active materials such as artificial graphite and lithium alloy (LiXM) may be used as the negative electrode active material. In LiXM, M is C, Si, Sn, Sb, Al, Mg, Ti, Bi, Ge, Pb, P, etc., and X is a natural number. Further, the negative electrode active material layer formed by the negative electrode active material may contain a known binder such as a styrene-butadiene copolymer.

[0040] Also, for example, the positive electrode includes a current collector formed of an aluminum foil or the like and a positive electrode active material. The positive electrode active material releases or occludes lithium ions into or from the non-aqueous electrolyte. Known positive electrode active materials such as LiNiO2 and LiNi1 / 3Co1 / 3Mn1 / 3O2 are used as the positive electrode active material. Further, it may further contain carbon black, trilithium phosphate, and a known binder.

[0041] The separator is a sheet-like member that electrically insulates the positive electrode and the negative electrode and provides a migration path for lithium ions between the positive electrode active material and the negative electrode active material. Examples of the separator include porous membranes formed of polyethylene and polypropylene. Note that the separator may have a single-layer structure or a multilayer structure.

[0042] Here, in the present embodiment, strip-shaped tapes 30, 32, 34, 36, and 38 are wound around the outer periphery of the electrode body 19. The tapes 30, 32, 34, 36, and 38 are provided at intervals in the longitudinal direction of the electrode body 19. In the present embodiment, as an example, five tapes are provided at equal intervals.

[0043] The tape 34 is provided at the central portion in the longitudinal direction of the electrode body 19 and extends in the short side direction of the electrode body 19. Further, a plurality of recesses 34A are provided in the tape 34. In this embodiment, as an example, two recesses 34A are provided on one surface of the electrode body 19, and two similar recesses 34A are also provided on the other surface.

[0044] Tapes 32 and 36 are provided on both sides of the tape 34 with a gap therebetween. For example, the distance between the tape 34 and the tape 32 is equal to the distance between the tape 34 and the tape 36. Further, a plurality of recesses 32A are provided in the tape 32, and a plurality of recesses 36A are provided in the tape 36. Specifically, two recesses 32A are provided on one surface of the electrode body 19, and two similar recesses 32A and 36A are also provided on the other surface.

[0045] The tape 30 is provided on the side opposite to the tape 34 with respect to the tape 32. Further, the tape 38 is provided on the side opposite to the tape 34 with respect to the tape 36. A plurality of recesses 30A are provided in the tape 30, and a plurality of recesses 38A are provided in the tape 38. Specifically, two recesses 30A are provided on one surface of the electrode body 19, and two similar recesses 30A and 38A are also provided on the other surface.

[0046] Here, at least a part of the recesses in the adjacent tapes when viewed from the longitudinal direction of the electrode body 19 overlap. In this embodiment, as an example, the recesses 30A, 32A, 34A, 36A, and 38A overlap when viewed from the longitudinal direction of the electrode body 19. Although not shown, the recesses formed on the other surface (back surface) of the electrode body 19 also overlap when viewed from the longitudinal direction of the electrode body 19.

[0047] FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 5. As shown in this FIG. 6, a concave portion 30A and an adhesive portion 30B are formed on the adhesive surface of the tape 30 facing the electrode body 19. The adhesive portion 30B is adhered to the surface of the electrode body 19. Further, the concave portion 30A is recessed more than the other portion (adhesive portion 30B) and is separated from the surface of the electrode body 19 in a no-load state. That is, the concave portion 30A is a non-adhesive portion that is not adhered to the surface of the electrode body 19.

[0048] In this way, the concave portion 30A and the adhesive portion 30B are alternately provided in the extending direction of the tape 30. Similarly, for the other tapes 32, 34, 36, and 38 shown in FIG. 5, the concave portion and the adhesive portion are alternately provided in the extending direction of the tape, and the concave portion is a non-adhesive portion.

[0049] (Operation) Next, the operation of the battery cell 20 according to this embodiment will be described.

[0050] In the battery cell 20 according to this embodiment, the electrode body 19 is formed in a long shape by laminating a positive electrode, a negative electrode, and a separator. Further, the tapes 30, 32, 34, 36, and 38 are formed in a strip shape, extend in the short direction of the electrode body 19, and are wound around the outer periphery of the electrode body 19. Furthermore, the electrode body 19 around which the tapes 30, 32, 34, 36, and 38 are wound is sealed in a state of being accommodated in the laminate film 22. By winding the tapes 30, 32, 34, 36, and 38 around the outer periphery of the electrode body 19 in this way, the electrode body 19 can be restrained, and the displacement of the laminated electrodes can be suppressed.

[0051] Also, in each of the tapes 30, 32, 34, 36, and 38, recesses 30A, 32A, 34A, 36A, and 38A that are recessed more than other portions are provided in a part of the adhesive surface that adheres to the electrode body 19. As a result, in the recesses 30A, 32A, 34A, 36A, and 38A, the restraining force of the electrode body 19 is weaker than that of other portions, so that the gas generated in the electrode body 19 can be discharged without being trapped inside.

[0052] Furthermore, in the present embodiment, since the recesses 30A, 32A, 34A, 36A, and 38A formed in each of the tapes 30, 32, 34, 36, and 38 in the no-load state are separated from the surface of the electrode body 19, the gas inside the electrode body 19 can move freely in this portion.

[0053] Moreover, in the present embodiment, since a plurality of tapes are provided at intervals in the longitudinal direction of the electrode body 19, even if the electrode body 19 is long, the displacement of the laminated electrodes can be effectively suppressed.

[0054] Also, in the present embodiment, by providing the tape 34 at the central portion in the longitudinal direction of the electrode body 19 that expands the most thermally, the thermal expansion of the battery cell 20 can be suppressed.

[0055] Furthermore, in the present embodiment, at least a part of the recesses in the adjacent tapes as viewed from the longitudinal direction of the electrode body 19 overlap. As a result, the gas generated in the central portion of the electrode body 19 can easily escape in the longitudinal direction.

[0056] In particular, in the present embodiment, the recesses 30A, 32A, 34A, 36A, and 38A coincide as viewed from the longitudinal direction of the electrode body 19. As a result, the gas generated in the central portion of the electrode body 19 can easily escape in the longitudinal direction through the inside of the portion where the recesses are formed. In this way, the battery cell 20 of the present embodiment can suppress the escape of gas during charge and discharge while restraining the electrode body 19.

[0057] In the above embodiment, as shown in FIG. 5, the concave portions 30A, 32A, 34A, 36A, and 38A are provided at the same positions in the longitudinal direction of the electrode body 19, but the present invention is not limited to this. For example, the structure of the modified example shown in FIG. 7 may be adopted.

[0058] (Modified Example) FIG. 7 is a schematic view of the electrode body 19 according to the modified example as viewed from the thickness direction. As shown in FIG. 7, in this modified example, a tape 42 is provided between the tapes 30 and 34 instead of the tape 32. Also, a tape 44 is provided between the tapes 34 and 38 instead of the tape 36.

[0059] The tape 42 is provided with a concave portion 42A. The concave portion 42A is formed to be wider than the concave portion 30A of the tape 30 and is provided at a position that does not overlap with the concave portion 30A when viewed from the longitudinal direction of the electrode body 19. Note that one concave portion 42A is provided on one surface of the electrode body 19, and one concave portion 42A is also provided on the other surface of the electrode body 19.

[0060] The tape 44 is provided with a concave portion 44A. The concave portion 44A is formed to be wider than the concave portion 30A of the tape 30 and is provided at a position that does not overlap with the concave portion 30A when viewed from the longitudinal direction of the electrode body 19. Note that one concave portion 44A is provided on one surface of the electrode body 19, and one concave portion 44A is also provided on the other surface of the electrode body 19.

[0061] By providing concave portions at different positions in the longitudinal direction of the electrode body 19 as in this modified example, the path of the gas generated in the electrode body 19 can be changed. Also, since the adhesive portions where the tape and the electrode body are adhered and the non-adhesive portions are alternately arranged in the longitudinal direction of the electrode body 19, it is possible to suppress a local decrease in the restraining force of the electrode body 19.

[0062] Although the battery cell 20 according to the embodiment and the modification has been described above, the present invention is not limited thereto, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, the width of the tape wound around the electrode body 19 may be changed, or the width of the tape may be changed between the central portion and the gripping portion in the longitudinal direction of the electrode body 19.

[0063] Alternatively, one wide tape may be wound around the electrode body 19. In this case, by providing a concave portion on the adhesive surface of the tape so that gas can easily escape, even a wide tape can suppress the escape of gas during charge and discharge while restraining the electrode body.

[0064] Furthermore, in the above embodiment, the concave portion is configured to be separated from the surface of the electrode body 19 in the no-load state, but the present invention is not limited thereto. For example, a configuration in which the concave portion provided on the tape contacts the surface of the electrode body 19 in the no-load state may be used. Even in this case, in the concave portion, since the restraining force of the electrode body 19 is weaker than that of other portions, a path for gas to escape can be set inside this portion.

[0065] Regarding the above embodiment, the following supplementary notes are disclosed.

[0066] (Supplementary Note 1) A long electrode body formed by laminating a positive electrode, a negative electrode, and a separator, A strip-shaped tape extending in the short direction of the electrode body and wound around the outer periphery of the electrode body, A laminate film for sealing in a state where the electrode body around which the tape is wound is accommodated, having In a part of the adhesive surface of the tape that adheres to the electrode body, a concave portion that is recessed more than other portions is provided. A battery cell. (Supplementary Note 2) The battery cell according to Supplementary Note 1, wherein the concave portion is separated from the surface of the electrode body in the no-load state. (Supplementary Note 3) The battery cell according to Supplementary Note 1 or Supplementary Note 2, wherein a plurality of the tapes are provided at intervals in the longitudinal direction of the electrode body. (Appendix 4) The battery cell according to Appendix 3, wherein at least one of the tapes is provided at a central portion in the longitudinal direction of the electrode body. (Appendix 5) A plurality of the concave portions are provided. The battery cell according to Appendix 3 or Appendix 4, wherein at least a part of the concave portions in the adjacent tapes as viewed from the longitudinal direction of the electrode body overlap each other.

Explanation of Reference Numerals

[0067] 19 Electrode body 20 Battery cell 22 Laminate film 30 Tape 30A Concave portion 32 Tape 32A Concave portion 34 Tape 34A Concave portion 36 Tape 36A Concave portion 38 Tape 38A Concave portion 42 Tape 42A Concave portion 44 Tape 44A Concave portion

Claims

1. A long electrode body formed by laminating a positive electrode, a negative electrode, and a separator, A strip-shaped tape extending in the short direction of the electrode body and wound around the outer periphery of the electrode body, A laminate film that seals the electrode body with the tape wound around it in a contained state, having, In a part of the adhesive surface of the tape that adheres to the electrode body, a recess that is recessed more than other parts is provided. A battery cell.

2. The battery cell according to claim 1, wherein the recess is spaced apart from the surface of the electrode body in a no-load state.

3. The battery cell according to claim 1 or claim 2, wherein a plurality of the tapes are provided at intervals in the longitudinal direction of the electrode body.

4. The battery cell according to claim 3, wherein at least one of the plurality of tapes is provided at a central portion in the longitudinal direction of the electrode body.

5. A plurality of the recesses are provided, The battery cell according to claim 4, wherein at least a part of the recesses in the adjacent tapes as viewed from the longitudinal direction of the electrode body overlap.

Images