Manufacturing method of battery

Abstract

To provide a manufacturing method of a battery capable of suppressing an excessive increase in temperature of a pair of side parts of a metal foil, which is parts where an electrode mixture is not provided, when the electrode mixture is dried by applying a radiant heat to the electrode mixture provided on one surface of the metal foil in a thickness direction and the metal foil.SOLUTION: A manufacturing method of a battery includes: a slit forming step of providing a slit 37 extending from a pair of side edge parts of a metal foil, on a pair of side parts 33, of a metal foil 30 having a strip shape extending along a predetermined direction and having an electrode mixture 40 formed on a first surface on one side in a thickness direction, where the electrode mixture is not formed; a bending step of bending each side part so that a first portion 34 which is a portion on a side edge side of each side part faces a second portion 35 which is a portion closer to a center side in a width direction of the metal foil than the first portion of the side part, from one side in the thickness direction; and a heating step of applying the radiant heat to the metal foil and the electrode mixture from a heat source 19 located on one side of the metal foil and the electrode mixture.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 below discloses an invention in which a coating film is irradiated with far-infrared rays having a wavelength that is highly absorbent for organic solvents, thereby evaporating the organic solvent from the entire coating film and bringing the coating film to a dry state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-063495 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, an electrode mixture can be formed (one of a negative electrode active material layer and a positive electrode active material layer is applied) on one side of a band-shaped metal foil that is a component of a battery and extends in a predetermined direction, excluding both widthwise sides, and the electrode mixture can be dried by applying infrared rays (radiant heat) from a heat source to the electrode mixture on one side of the metal foil.

[0005] However, the infrared rays emitted from the heat source reach both sides of the metal foil in the width direction. This can cause excessive temperature rises on both sides of the metal foil. If the temperature on both sides of the metal foil becomes excessively high, surface oxidation can occur on both sides, or the conductivity of both sides can decrease. Furthermore, if a resin sealant is provided on both sides, the sealing performance of the sealant can be reduced.

[0006] In consideration of the above facts, the present invention aims to provide a method for manufacturing a battery that can prevent a pair of side portions of the metal foil, where the electrode mixture is not provided, from becoming excessively hot when radiant heat is applied to the electrode mixture and the metal foil provided on one side surface of the metal foil in the thickness direction to dry the electrode mixture. [Means for solving the problem]

[0007] A first embodiment of a method for manufacturing a battery includes a slit forming step of forming slits extending from a pair of side edges of a metal foil having a band shape extending along a predetermined direction and an electrode composite formed on a first surface, which is one surface in the thickness direction, in a pair of side portions on which the electrode composite is not formed; a folding step of folding the side portions so that a first portion, which is a portion of the side edge side of the side portions, faces a second portion, which is a portion of the side portions closer to the center in the width direction of the metal foil than the first portion of the side portions, from the one side in the thickness direction; and a heating step of applying radiant heat to the metal foil and the electrode composite from a heat source located on the one side of the metal foil and the electrode composite.

[0008] A first embodiment of the battery manufacturing method includes a slit forming step of forming slits extending from a pair of side edges of a metal foil having a band-like shape extending along a predetermined direction and an electrode composite formed on a first surface, which is one side in the thickness direction, in a pair of side portions where the electrode composite is not formed, and a folding step of folding the side portions so that a first portion, which is a portion of each side edge of the metal foil, faces a second portion, which is a portion of the side closer to the center in the width direction of the metal foil than the first portion of the side, from the one side in the thickness direction. The first embodiment of the battery manufacturing method further includes a heating step of applying radiant heat to the metal foil and the electrode composite from a heat source located on one side of the metal foil and the electrode composite. Therefore, although radiant heat reaches each side portion of the metal foil from the heat source, because each side portion is folded, the heat capacity of the side portions is likely to be higher than if the side portions were not folded. Therefore, the radiant heat reaching the side portions prevents the pair of side portions from becoming excessively hot.

[0009] A second aspect of the battery manufacturing method is the method of the first aspect, wherein the heat source is a light source capable of emitting electromagnetic waves that exert the radiant heat on the metal foil and the electrode mixture; The electromagnetic wave absorption rate of the first surface of the metal foil is higher than the electromagnetic wave absorption rate of the second surface, which is the surface on the other side in the thickness direction of the metal foil.

[0010] In the battery manufacturing method of the second embodiment, when the side portions are folded, electromagnetic waves (radiant heat) reach the second surfaces of the first portions of the side portions. However, the electromagnetic wave absorption rate of the second surface of the metal foil is lower than the electromagnetic wave absorption rate of the first surface of the metal foil. Therefore, the battery manufacturing method of the second embodiment tends to prevent the pair of side portions from becoming excessively hot due to the radiant heat reaching the side portions.

[0011] The battery manufacturing method of the third aspect is the same as that of the second aspect, and includes a shape restoration step that is performed after the heating step and returns the first portion of the side portion to a state where it does not face the second portion from the one side in the thickness direction.

[0012] According to the battery manufacturing method of the third aspect, the first portion of the side portion is returned to a state where it does not face the second portion from one side in the thickness direction.

[0013] A fourth aspect of the battery manufacturing method is the same as that of the third aspect, and includes a cutting step that is performed after the shape restoration step, in which the metal foil is cut along the width direction at two locations located on both sides of the electrode composite in the predetermined direction to manufacture electrode units having the electrode composite and the cut metal foil; a first laminate manufacturing step that provides a resin sealing material on the outer periphery of the metal foil that constitutes the outer periphery of a plurality of the electrode units to manufacture a plurality of first laminates that are integrated with the electrode units and the sealing material; and a stacking step that alternately stacks a plurality of the first laminates and a plurality of the second laminates in the thickness direction while arranging a second laminate having a separator and a resin spacer provided on the outer periphery of the separator between two of the first laminates.

[0014] According to the battery manufacturing method of the fourth aspect, a stack is obtained in which a plurality of first stacks and a plurality of second stacks are alternately stacked. [Effects of the Invention]

[0015] As described above, the battery manufacturing method of the present invention has the excellent effect of preventing the pair of side portions of the metal foil, which are not provided with the electrode mixture, from becoming excessively hot when radiant heat is applied to the electrode mixture and the metal foil provided on one side surface of the metal foil in the thickness direction to dry the electrode mixture. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic perspective view of a manufacturing apparatus capable of carrying out a battery manufacturing method according to an embodiment, a metal foil, and an electrode mixture. [Figure 2] 1 is a flowchart showing the steps of a manufacturing method according to an embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view taken along the arrow line 3-3 in FIG. [Figure 4] FIG. 2 is a schematic cross-sectional view of a battery. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a manufacturing method of a battery according to an embodiment (hereinafter referred to as "manufacturing method") will be described with reference to the accompanying drawings. Note that the arrows UP, FR, and LH shown in each drawing indicate the upper side in the up-down direction, the front side in the front-to-back direction, and the left side in the left-to-right direction, respectively.

[0018] A first manufacturing apparatus 10 shown in FIG. 1 is used to carry out a manufacturing method. The first manufacturing apparatus 10 includes multiple pairs of conveying rollers 12 (only one pair of conveying rollers 12 is shown in FIG. 1 ) arranged along the conveying direction of a metal foil (electrode body) 30 (described later) and connected to an electric motor (not shown). The pairs of conveying rollers 12 are spaced apart vertically. A long strip-shaped metal foil 30 extending in a predetermined direction (front-rear direction) is sandwiched between the upper and lower conveying rollers 12, and the conveying rollers 12 rotate in the predetermined direction, thereby conveying the metal foil 30 from the upstream side to the downstream side along the direction of arrow A (forward) in FIG. 1 . The upper surface (one side in the thickness direction) of the metal foil 30 is a first surface 31, and the lower surface (the other side in the thickness direction) of the metal foil 30 is a second surface 32. The metal foil 30 of this embodiment is formed by laminating two strip-shaped metal materials of different types together in the thickness direction. Therefore, the absorptance (wavelength absorptance) of laser light (electromagnetic wave) LS2 emitted by a light source (heat source) 19 (described later) differs between the first surface 31 and the second surface 32. Specifically, the absorptance of the laser light LS2 by the first surface 31 is greater than the absorptance of the laser light LS2 by the second surface 32.

[0019] The first manufacturing apparatus 10 further includes, in order from the upstream side, a coating device (not shown), a first cutting device 14, folding rollers 16, a drying oven 18, and a second cutting device 20.

[0020] A coating device disposed above the metal foil 30 intermittently coats the upper surface (first surface 31) of the metal foil 30, which has been conveyed downstream by the conveying rollers 12, with a negative electrode composite (electrode composite) 40 containing a negative electrode active material. As shown in FIG. 1 , the coating device applies the negative electrode composite 40 only to an area excluding both side portions 33 in the left-right direction of the first surface 31. In other words, the negative electrode composite 40 is not provided on both side portions 33 in the left-right direction of the first surface 31. Furthermore, adjacent negative electrode composites 40 are spaced apart in the direction of arrow A.

[0021] The first cutting device 14 is located downstream of the coating device and directly above the metal foil 30. The first cutting device 14 is equipped with a pair of laser light sources 15 spaced apart in the left-right direction. Each laser light source 15 is movable in the left-right direction and can emit laser light LS1 downward. Each laser light source 15 has the function of forming a slit 37 that extends linearly along the left-right direction on each side portion 33 of the metal foil 30.

[0022] Pairs of folding rollers 16 spaced apart in the left-right direction are arranged at two locations downstream of the first cutting device 14. That is, the first manufacturing apparatus 10 is equipped with four folding rollers 16. The left-right distance between the pair of folding rollers 16 spaced apart in the left-right direction is slightly shorter than the left-right dimension of the metal foil 30. Each folding roller 16 is rotatable around its own rotation axis 17.

[0023] Drying furnace 18 is located between upstream folding roller 16 and downstream folding roller 16 and directly above metal foil 30 (negative electrode composite material 40). Drying furnace 18 has a light source 19 that can emit laser light LS2 downward.

[0024] The second cutting device 20 is located downstream of the drying furnace 18. The second cutting device 20 has a function of linearly cutting the metal foil 30 in the left-right direction. The second cutting device 20 may be, for example, a mechanical cutting device or a cutting device that uses laser light.

[0025] Next, the manufacturing method of this embodiment will be described with reference to Fig. 2. As shown in Fig. 2, the manufacturing method of this embodiment includes a coating step, a slitting step, a folding step, a heating step, a shape restoration step, a cutting step, a first laminate manufacturing step, a second laminate manufacturing step, a lamination step, and a finishing step.

[0026] When the electric motor is operated, each of the conveying rollers 12 rotates in a predetermined direction, and the metal foil 30 sandwiched between the pair of upper and lower conveying rollers 12 is conveyed in the direction of arrow A.

[0027] In this state, the coating step is first performed. That is, the coating device intermittently coats the negative electrode composite 40 containing the negative electrode active material onto the first surface 31 of the metal foil 30, which is being transported downstream by the transport rollers 12, in an area excluding both side portions 33.

[0028] Next, the slit forming step is performed. That is, the pair of laser light sources 15 of the first cutting device 14 emits laser light LS1 downward while moving left and right. As a result, slits 37 are formed in each side portion 33 of the metal foil 30, as shown in FIG.

[0029] Next, a folding step is performed. That is, the portion (end surface) of each side portion 33 where the slit 37 is formed contacts the corresponding upstream folding roller 16, thereby rotating each folding roller 16. As a result, the first portion 34, which is a portion located outside the central position in the left-right direction of each side portion 33, is folded upward relative to the second portion 35, which is a portion located between the central position and the negative electrode composite material 40, so that each first portion 34 faces the second portion 35 from above (one side in the thickness direction of the metal foil 30) (see FIGS. 1 and 3 ).

[0030] Next, a heating step is performed. That is, as shown in FIGS. 1 and 3, the light source 19 of the drying furnace 18 emits a laser beam LS2 downward. The light source 19 is capable of controlling (adjusting) the emission angle θ (see FIG. 3) of the laser beam LS2. In this embodiment, as shown in FIG. 3, the laser beam LS2 emitted from the light source 19 is irradiated onto the upper surfaces of the metal foil 30 and the negative electrode composite material 40 in a region between the left-right central position of the first portion 34 (second surface 32) and the right-left central position of the first portion 34. That is, radiant heat emitted from the light source 19 reaches the upper surfaces of the metal foil 30 and the negative electrode composite material 40. Therefore, the negative electrode composite material 40 is heated by the laser beam LS2, and the negative electrode composite material 40 is dried. Furthermore, the left and right side portions 33 are heated by radiant heat reaching the left and right side portions 33 from the laser beam LS2.

[0031] Next, a shape restoration step is performed. That is, when the side portions 33 pass forward under the downstream folding rollers 16, the left and right first portions 34, which have been folded upward by the folding rollers 16, are restored to their initial shapes so as to be positioned substantially on the same plane as the second portions 35. That is, the first portions 34 are restored to a state in which they do not face the second portions 35 from above.

[0032] Next, the cutting step is performed. That is, the second cutting device 20 linearly cuts the portion of the metal foil 30 where the negative electrode composite material 40 is not applied (the portion where the slit 37 is formed) along the left-right direction. That is, the metal foil 30 is linearly cut at two locations located on both sides of the negative electrode composite material 40 in the front-rear direction. As a result, an electrode unit 45 is formed, which is an integral body of a portion of the metal foil 30 and the negative electrode composite material 40 and has a substantially square planar shape (see FIG. 1). This electrode unit 45 is a negative electrode terminal electrode (electrode) 60 (see FIG. 4).

[0033] The above-described coating step, slit forming step, folding step, heating step, shape restoration step, and cutting step are repeatedly performed to manufacture a plurality of negative terminal electrodes 60.

[0034] A plurality of positive terminal electrodes (electrodes) 65 (see FIG. 4) are manufactured using a second manufacturing apparatus (not shown) having a configuration similar to that of the first manufacturing apparatus 10. The second manufacturing apparatus has the same configuration as the first manufacturing apparatus 10, except that it includes a coating device that coats the first surface 31 of the metal foil 30 with a positive electrode composite (electrode composite) 50.

[0035] Furthermore, a plurality of bipolar electrodes (electrodes) 70 (see FIG. 4 ) are manufactured using a third manufacturing apparatus (not shown) having a configuration similar to that of the first manufacturing apparatus 10. This third manufacturing apparatus has the same configuration as the first manufacturing apparatus 10, except that it is equipped with a coating device that coats one of the first surface 31 and the second surface 32 of the metal foil 30 with the negative electrode composite material 40 and a coating device that coats the other of the first surface 31 and the second surface 32 with the positive electrode composite material 50 at a location corresponding to each negative electrode composite material 40, and that it is equipped with two sets (eight rollers) of folding rollers 16 and two drying ovens 18. In the third manufacturing apparatus, for example, first, the negative electrode composite material 40 is coated on the first surface 31 facing upward by an upstream coating device, a slit 37 is formed in the metal foil 30 by a first cutting device 14, the first regions 34 of each side portion 33 are folded upward by four upstream folding rollers 16, and the negative electrode composite material 40 is dried by an upstream drying furnace 18 (light source 19). After each first region 34 returns to a state where it does not face the second region 35 from above and the second surface 32 is oriented upward, the positive electrode composite material 50 is coated on the second surface 32 by a downstream coating device, the first regions 34 of each side portion 33 are folded upward by four downstream folding rollers 16, and the positive electrode composite material 50 is dried by a downstream drying furnace 18 (light source 19). Furthermore, after each of the first portions 34 has returned to a state where it does not face the second portions 35 from above, the metal foil 30 is cut by the second cutting device 20. In this way, the bipolar electrode 70 is obtained.

[0036] A plurality of negative electrode terminal electrodes 60, positive electrode terminal electrodes 65 and bipolar electrodes 70 are manufactured by repeatedly performing the coating step, slit forming step, folding step, heating step, shape restoration step and cutting step using the first manufacturing equipment 10, the second manufacturing equipment and the third manufacturing equipment.

[0037] Next, a first laminate manufacturing step is performed. That is, a resin sealant 55 (see FIG. 4) is attached to the entire outer periphery of the metal foil 30 of each negative electrode terminal electrode 60, each positive electrode terminal electrode 65, and each bipolar electrode 70. The sealant 55 is a frame-shaped body having a substantially square planar shape, and a groove is formed on the entire inner periphery of the sealant 55. The sealant 55 is welded to the metal foil 30 with the outer periphery of the metal foil 30 inserted into the groove. Hereinafter, the integrated body of the negative electrode terminal electrode 60 and the positive electrode composite material 50 will be referred to as a first laminate 60T, the integrated body of the positive electrode terminal electrode 65 and the positive electrode composite material 50 will be referred to as a first laminate 65T, and the integrated body of the bipolar electrode 70 and the positive electrode composite material 50 will be referred to as a first laminate 70T.

[0038] Next, a second laminate manufacturing step is performed. Specifically, resin spacers 77 are attached to the outer periphery of a plurality of separators 75 (see FIG. 4), each of which has a substantially square planar shape. The separators 75 and the spacers 77 are then welded (spot welded). Hereinafter, the integrated product of the separators 75 and the spacers 77 will be referred to as a second laminate 75T.

[0039] Next, the stacking step is performed, that is, as shown in Fig. 4, one first stack 60T, one first stack 65T, a plurality of first stacks 70T positioned between the first stacks 60T and 65T, and a plurality of second stacks 75T positioned between adjacent electrodes (negative terminal electrode 60, positive terminal electrode 65, bipolar electrode 70) are stacked in the vertical direction.

[0040] Next, a finishing step is performed. That is, the laminate of the first laminates 60T, 65T, 70T and the second laminate 75T is placed in a molding die (not shown), and the sealant 55 and the spacer 77 are heated. As a result, the resin sealant 55 and the spacer 77 are partially melted, and a resin frame 80 (see FIG. 4) is formed, which is a frame-shaped body having a substantially square shape in a plan view. Furthermore, a liquid injection frame (not shown) is formed on the outer peripheral surface of the resin frame 80.

[0041] Furthermore, in the finishing step, a non-aqueous electrolyte solution is injected into the internal space V of each battery cell. Note that one battery cell is made up of one separator 75, negative electrode composite 40 located on one side of separator 75, and positive electrode composite 50 located on the other side of separator 75.

[0042] Furthermore, in a finishing step, the hole provided in the liquid filling frame for injecting the electrolyte into the internal space V is closed. This completes the lithium ion secondary battery (bipolar battery) 90 shown in FIG.

[0043] As described above, the manufacturing method of this embodiment includes a slit forming step of forming slits 37 extending from a pair of side edges of the metal foil 30 in a pair of side regions 33 of the metal foil 30 on which no electrode composite material is formed, the side regions 33 having electrode composite materials (negative electrode composite material 40, positive electrode composite material 50) formed on the first surface 31, and a folding step of folding the side regions 33 of the metal foil 30 so that a first region 34, which is a region on the side edge side of each side region 33 of the metal foil 30, faces from above a second region 35, which is a region of the side region 33 closer to the center in the width direction of the metal foil 30 than the first region 34. The manufacturing method further includes a heating step of applying radiant heat to the metal foil 30 and the electrode composite materials (negative electrode composite material 40, positive electrode composite material 50) from a light source 19 located above the metal foil 30 and the electrode composite materials. Therefore, although radiant heat reaches each side portion 33 of the metal foil 30 from the light source 19, the thickness of each side portion 33 is increased by folding, and therefore the heat capacity of the side portions 33 is higher than when they are not folded. Therefore, the radiant heat reaching the side portions 33 prevents the pair of side portions 33 from becoming excessively hot.

[0044] Furthermore, in the manufacturing method of this embodiment, when the side portions 33 are folded, the laser light LS2 (radiant heat) reaches the second surfaces 32 of the first portions 34 of the side portions 33. As described above, the absorptance of the laser light LS2 by the second surfaces 32 of the metal foil 30 is lower than the absorptance of the laser light LS2 by the first surfaces 31. Therefore, when the laser light LS2 is irradiated onto the composite materials (negative electrode composite material 40, positive electrode composite material 50) coated on the first surfaces 32, the laser light LS2 that reaches the side portions 33 is likely to be reflected by the second surfaces 32 of the first portions 34. Therefore, the radiant heat (laser light LS2) that reaches each side portion 33 is likely to prevent each side portion 33 from becoming excessively hot.

[0045] The battery manufacturing method according to the embodiment has been described above, but the design can be appropriately modified within the scope of the present invention.

[0046] For example, the light source 19 may emit electromagnetic waves other than the laser light LS2. An example of the electromagnetic waves is infrared rays.

[0047] A carbon coating may be applied to either surface of the metal foil 30. However, because a carbon coating has a high absorption rate (wavelength absorption rate) of electromagnetic waves, it is preferable to apply a carbon coating to the first surface 31 coated with the electrode composite material rather than to the second surface 32 not coated with the electrode composite material.

[0048] When manufacturing a bipolar electrode 70 using metal foil 30, side portion 33 is folded upward only when electromagnetic waves are irradiated onto the electrode composite coated on first surface 31, and side portion 33 does not need to be folded upward when electromagnetic waves are irradiated onto the electrode composite coated on second surface 32.

[0049] The absorptance (wavelength absorptance) of the electromagnetic waves emitted by the light source (heat source) 19 at the first surface 31 of the metal foil 30 may be the same as the absorptance of the electromagnetic waves at the second surface 32. [Explanation of symbols]

[0050] 19 Light source (heat source) 30 Metal foil (electrode body) 31 Page 1 32 2nd page 33 Side 34 Part 1 35 Part 2 37 Slit 40 Negative electrode composite material (electrode composite material) 45 Electrode Unit 50 Positive electrode mixture (electrode mixture) 55 Sealing material 60T 65T 70T 1st laminate 75 Separator 75T 2nd laminate 77 Spacer 90 Battery (Bipolar Battery) LS2 Laser light (electromagnetic waves)

Claims

1. a slit forming step of forming slits extending from a pair of side edge portions of the metal foil in a pair of side portions on which the electrode mixture is not formed, the metal foil having a band shape extending along a predetermined direction and a first surface which is one surface of the metal foil in a thickness direction; a folding step of folding the side portion so that a first portion, which is a portion on the side edge side of the side portion, faces a second portion, which is a portion of the side portion closer to the center in the width direction of the metal foil than the first portion of the side portion, from the one side in the thickness direction; and a heating step of applying radiant heat to the metal foil and the electrode mixture from a heat source located on the one side of the metal foil and the electrode mixture; A method for manufacturing a battery having the above structure.

2. the heat source is a light source capable of emitting electromagnetic waves that exert radiant heat on the metal foil and the electrode mixture, The method for manufacturing a battery according to claim 1 , wherein the electromagnetic wave absorption rate of the first surface of the metal foil is greater than the electromagnetic wave absorption rate of the second surface, which is the surface on the other side in the thickness direction of the metal foil.

3. 3. The method for manufacturing a battery according to claim 1, further comprising a shape restoring step, which is carried out after the heating step, of restoring the first portion of the side portion to a state where it does not face the second portion from the one side in the thickness direction.

4. a cutting step, which is executed after the shape restoring step, of cutting the metal foil along the width direction at two locations located on both sides of the electrode composite in the predetermined direction to manufacture an electrode unit including the electrode composite and the cut metal foil; a first laminate manufacturing step of providing a resin sealing material on the outer periphery of the metal foil that constitutes the outer periphery of the plurality of electrode units, thereby manufacturing a plurality of first laminates that are integral bodies of the electrode units and the sealing material; and a lamination step of alternately laminating a plurality of the first laminates and a plurality of the second laminates in the thickness direction while disposing a second laminate having a separator and a resin spacer provided on an outer periphery of the separator between two of the first laminates; The method for manufacturing a battery according to claim 3, comprising:

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