Manufacturing apparatus of secondary battery and magnetic flux application device

Abstract

To efficiently apply a magnetic flux to an electrode sheet.SOLUTION: A manufacturing apparatus 50 of a secondary battery, comprises: a magnetic flux application device 60 having a plurality of pairs of magnet pairs 85 formed by a pair of magnets 80 that is oppositely arranged each other while having opposite surfaces 81s and 82s of which each polarity is different. In the magnetic flux application device 60, by passing an electrode sheet 35N to a gap δ between the opposite surfaces 81s and 82s in each magnet pair 85, an arrangement direction of a negative electrode active material contained in a negative electrode mixture 37 coated to the electrode sheet 35N is controlled. Also, each magnet pair 85 is arranged so as to be paralleled to first and second arrangement directions L1 and L2 that are crossed along a width direction of the electrode sheet 35N, passing through the gap δ between the opposite surfaces 81s and 82s. Then, the pair of magnet pairs 85 that are adjacent to each of the arrangement directions L1 and L2 are contacted and arranged in a counter magnetic flux direction.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a manufacturing apparatus for secondary batteries and a magnetic flux applying apparatus.

Background Art

[0002] Conventionally, for example, as described in Patent Document 1, there is a manufacturing apparatus for secondary batteries that applies a magnetic flux in a direction orthogonal to an electrode sheet on which an electrode mixture is coated. That is, by applying a magnetic flux to the electrode mixture coated on the electrode sheet, the orientation of the electrode active material and the conductive material contained in the electrode mixture can be controlled. For example, in a negative electrode mixture using hexagonal platelet-shaped graphite as a negative electrode active material, the scale shape of the negative electrode active material is oriented along the direction of the applied magnetic flux, that is, in a state of standing on the base material of the electrode sheet that serves as a current collector. And thereby, by reducing the internal resistance, excellent battery performance can be ensured.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Also, in order to efficiently apply a magnetic flux to the electrode sheet as described above, the arrangement of the magnets that form the magnetic flux is important. And since there is no detailed description about this point in the above Patent Document 1, further improvement has been desired.

Means for Solving the Problems

[0005] Each aspect of a manufacturing apparatus for secondary batteries and a magnetic flux applying apparatus that solve the above problems is described. Aspect 1 is a manufacturing apparatus for a secondary battery including a pair of magnets having opposing surfaces with different polarities and arranged to face each other, wherein the alignment of the negative electrode active material contained in the negative electrode composite material coated on the electrode sheet is controlled by passing the electrode sheet through the gap between the opposing surfaces. The manufacturing apparatus includes a plurality of sets of the pair of magnets arranged side by side in first and second arrangement directions intersecting each other along the spreading direction of the electrode sheet passing through the gap between the opposing surfaces, and each set of the pair of magnets adjacent to each other in each arrangement direction is arranged in contact with each other with opposite magnetic flux directions.

[0006] According to the above configuration, by arranging each pair of magnets in contact, it is possible to suppress the arrangement space for securing the magnetic flux amount necessary for aligning the negative electrode active material in the negative electrode composite material coated on the electrode sheet to a small size. As a result, the time required for the electrode sheet to pass through the group of pairs of magnets in which each pair of magnets is arranged in contact, that is, the alignment time of the electrode sheet, can be shortened.

[0007] Also, by arranging a large number of pairs of magnets with a small area of the opposing surface, the magnetic attraction force per pair of magnets can be reduced. As a result, it is possible to easily handle each pair of magnets.

[0008] Furthermore, taking advantage of this, it is possible to stably hold a pair of magnets in a state where a small value is set for the gap between the opposing surfaces. Also, the magnetic flux density of each pair of magnets can be set high. As a result, a stronger magnetic flux can be applied to the electrode sheet passing through the gap between the opposing surfaces. As a result, even when the negative electrode composite material coated on the electrode sheet has a higher viscosity, the negative electrode active material in the coated negative electrode composite material can be appropriately aligned.

[0009] Aspect 2 is the manufacturing apparatus for a secondary battery according to Aspect 1, wherein each of the opposing surfaces is rectangular. According to the above configuration, it is easy to arrange each pair of magnets in contact in the first and second arrangement directions. As a result, it is possible to efficiently apply magnetic flux to the electrode sheet.

[0010] Aspect 3 is a manufacturing apparatus for a secondary battery according to Aspect 2, in which the first and second array directions have an inclination with respect to the passing direction of the electrode sheet. According to the above configuration, at the end position of the magnet pair group formed by each magnet pair, a portion where the magnetic balance near the corner of the magnet is disrupted is formed. As a result, a highly oriented region with a high magnetic flux density in a direction orthogonal to the electrode sheet passing through the gap of the magnet pair can be formed.

[0011] That is, in the highly oriented region, the negative electrode active material contained in the negative electrode composite material becomes more significantly aligned along the magnetic flux in the direction orthogonal to the electrode sheet. As a result, higher battery performance can be ensured.

[0012] Also, when the negative electrode active material in the negative electrode composite material is uniformly and strongly oriented, the contact area with the base material serving as the current collector decreases. As a result, when the negative electrode composite material is dried, the negative electrode active material in the negative electrode composite material tends to move to the surface side, which may reduce the adhesion of the negative electrode active material layer formed by the negative electrode composite material coated on the base material.

[0013] However, according to the above configuration, for the portions other than the highly oriented region, the orientation can be kept relatively low, and an appropriate contact state of the negative electrode active material with the base material can be ensured. As a result, the movement to the surface side during drying can be suppressed, and a high adhesion of the negative electrode active material layer laminated on the base material can be ensured.

[0014] Aspect 4 is a manufacturing apparatus for a secondary battery according to Aspect 3, in which the diagonal direction of each opposed surface coincides with the passing direction of the electrode sheet. According to the above configuration, in the width direction of the electrode sheet passing through the gap of each magnet pair, a plurality of highly oriented regions spaced at equal intervals can be formed. As a result, more effectively, based on the density of the magnetic flux applied to the electrode sheet, a decrease in adhesion caused by the surface side movement of the negative electrode active material during drying of the negative electrode composite material can be suppressed.

[0015] Aspect 5 is a manufacturing apparatus for a secondary battery according to any one of Aspects 1 to 4, wherein each of the magnets has a cubic shape. According to the above configuration, the opposing surfaces of each magnet pair are square. As a result, in the first and second arrangement directions orthogonal to each other, the magnet pairs can be arranged in contact with each other without a gap. As a result, the magnetic flux can be applied to the electrode sheet more efficiently.

[0016] Aspect 6 is a magnetic flux applying device that includes a pair of magnet pairs each having opposing surfaces with different polarities and arranged to face each other, and applies a magnetic flux to an electrode composite material coated on the electrode sheet by passing the electrode sheet through a gap between the opposing surfaces. The magnetic flux applying device includes a plurality of sets of the magnet pairs arranged side by side in first and second arrangement directions that intersect each other along the spreading direction of the electrode sheet passing through the gap between the opposing surfaces, and each set of the magnet pairs adjacent to each other in each arrangement direction is arranged in contact with each other with opposite magnetic flux directions.

Advantages of the Invention

[0017] According to the present invention, the application of magnetic flux to the electrode sheet can be performed efficiently.

Brief Description of the Drawings

[0018]

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DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of a secondary battery will be described with reference to the drawings. (Lithium Ion Secondary Battery) As shown in FIG. 1, the secondary battery 1 includes an electrode body 10 in which a positive electrode 3, a negative electrode 4, and a separator 5 are integrated, and a case 20 that houses the electrode body 10. The secondary battery 1 of this embodiment has a configuration as a lithium ion secondary battery in which the electrode body 10 in the case 20 is impregnated with a non-aqueous electrolyte (not shown).

[0020] Specifically, in the secondary battery 1 of this embodiment, the positive electrode 3, the negative electrode 4, and the separator 5 have a sheet-like outer shape and are laminated. By winding the laminate of the positive electrode 3, the negative electrode 4, and the separator 5, an electrode body 10 is formed in which the positive and negative electrodes and the separator 5 are alternately arranged in the radial direction with the separator 5 sandwiched between the positive electrode 3 and the negative electrode 4.

[0021] Further, the case 20 of this embodiment includes a flat substantially rectangular box-shaped case body 21 and a lid member 22 that closes the open end 21x of the case body 21. The electrode body 10 of this embodiment has a flat outer shape corresponding to the box shape of the case 20.

[0022] (Electrode Sheet and Electrode Body) More specifically, as shown in FIG. 2, in the secondary battery 1 of the present embodiment, the positive electrode 3 and the negative electrode 4 each have a configuration as an electrode sheet 35 including a current collector 31 having a sheet-like outer shape and an electrode active material layer 32 laminated on the current collector 31.

[0023] Specifically, for the electrode sheet 35P for the positive electrode 3, a paste-like positive electrode mixture 37P containing a lithium transition metal oxide serving as a positive electrode active material is applied onto a base material 36P made of a material such as aluminum constituting the positive electrode current collector 31P. Further, for the electrode sheet 35N for the negative electrode 4, a slurry-like negative electrode mixture 37N containing a carbon-based material serving as a negative electrode active material is applied onto a base material 36N made of a material such as copper constituting the negative electrode current collector 31N. Furthermore, each of these positive electrode mixture 37 for the positive electrode 3 and negative electrode mixture 37 for the negative electrode 4 contains a binder. And in the secondary battery 1 of the present embodiment, by drying the electrode mixture 37 applied onto the base material 36, the corresponding positive electrode active material layer 32P and negative electrode active material layer 32N are formed on the positive and negative electrode sheets 35P and 35N, respectively.

[0024] Furthermore, in the secondary battery 1 of the present embodiment, these positive and negative electrode sheets 35P and 35N are each shaped into a strip. And the electrode body 10 of the present embodiment has a configuration as a wound body in which the positive and negative electrode sheets 35P and 35N laminated with the separator 5 interposed therebetween are wound around a winding shaft 10x extending in the width direction of the strip shape (the left-right direction in FIG. 2).

[0025] Note that in FIG. 2, the separator 5 and each electrode sheet 35 are wound in such a manner that the electrode sheet 35P constituting the positive electrode 3 is wound inside. However, this figure is an example showing the structure of the electrode body 10, and there may be a case where the separator 5 and each electrode sheet 35 are wound in such a manner that the electrode sheet 35N constituting the negative electrode 4 is wound inside. And thereby, it is determined whether the electrode sheet 35 disposed on the outermost shell of the electrode body 10 is the electrode sheet 35P constituting the positive electrode 3 or the electrode sheet 35N constituting the negative electrode 4.

[0026] Also, as shown in FIGS. 1 to 3, the lid member 22 of the case 20 is provided with a positive electrode terminal 38P and a negative electrode terminal 38N that protrude to the outside of the case 20. Further, each electrode sheet 35 is formed with an uncoated portion 39 where the electrode active material layer 32 is not formed on its current collector 31. And in the secondary battery 1 of the present embodiment, by using these uncoated portions 39, the electrode sheet 35P constituting the positive electrode 3 is electrically connected to the positive electrode terminal 38P, and the electrode sheet 35N constituting the negative electrode 4 is electrically connected to the negative electrode terminal 38N.

[0027] Specifically, the electrode body 10 of the present embodiment is housed in the case 20 in a state where its winding axis 10x is along the longitudinal direction (the left - right direction in FIG. 1) of the lid member 22 having a long and substantially rectangular plate shape. Further, in this state, the uncoated portion 39P of the electrode sheet 35P constituting the positive electrode 3 is connected to the positive electrode terminal 38P via a connection member 40P. And similarly, the uncoated portion 39N of the electrode sheet 35N constituting the negative electrode 4 is connected to the negative electrode terminal 38N via a connection member 40N.

[0028] Furthermore, an electrolytic solution 45 is injected into the case 20. That is, for the electrolytic solution 45 of the secondary battery 1 having a configuration as a lithium - ion secondary battery, a solution in which a lithium salt serving as a supporting salt is dissolved in an organic solvent is used. And the secondary battery 1 of the present embodiment is configured such that the electrode body 10 sealed in the case 20 is impregnated with the electrolytic solution 45.

[0029] (Magnetic Flux Application Device) As shown in FIG. 4, the manufacturing apparatus 50 used when manufacturing the secondary battery 1 of the present embodiment includes a magnetic flux application device 60 that applies a magnetic flux to the negative electrode composite material 37N coated on the base material 36N when manufacturing the electrode sheet 35N on the negative electrode 4 side.

[0030] Specifically, this magnetic flux applying device 60 includes first and second magnetic flux forming parts 61 and 62 that are arranged to face each other with a gap D in the vertical direction. And the magnetic flux applying device 60 of the present embodiment is configured to form a magnetic flux in the opposite direction in the gap D between the first and second magnetic flux forming parts 61 and 62. Also, in the manufacturing apparatus 50 of the present embodiment, the electrode sheet 35N on the negative electrode 4 side is continuously conveyed in the longitudinal direction of its strip shape while being wound around a plurality of rolls (not shown). Further, in the manufacturing apparatus 50 of the present embodiment, before the negative electrode composite material 37N coated on the base material 36N dries, this electrode sheet 35N passes through the gap D between the first and second magnetic flux forming parts 61 and 62 that constitute the magnetic flux applying device 60. Specifically, in the manufacturing apparatus 50 of the present embodiment, the first and second magnetic flux forming parts 61 and 62 pass the magnetic flux applying device 60 with the electrode sheet 35N sandwiched in the thickness direction. And the magnetic flux applying device 60 of the present embodiment is configured to apply the magnetic flux formed between the first and second magnetic flux forming parts 61 and 62 to the electrode sheet 35N passing through the gap D.

[0031] (Orientation effect by application of magnetic flux) That is, as shown in FIGS. 5 and 6, in the manufacturing apparatus 50 of the present embodiment, this magnetic flux applying device 60 applies a magnetic flux in a direction perpendicular to the electrode sheet 35N (the vertical direction in FIGS. 5 and 6) to the negative electrode composite material 37N coated on the electrode sheet 35N. And the manufacturing apparatus 50 of the present embodiment is configured to control the orientation of the negative electrode active material 65N contained in the negative electrode composite material 37N thereby.

[0032] For example, when the negative electrode active material 65N in the negative electrode composite material 37N is graphite 66 in the shape of a hexagonal plate crystal, its flake shape is oriented along the direction of the applied magnetic flux. That is, the flake shape of the negative electrode active material 65N stands on the base material 36N that becomes the negative electrode current collector 31N in the negative electrode composite material 37N. And the secondary battery 1 of the present embodiment is configured to ensure excellent battery performance by reducing the internal resistance thereby.

[0033] Still, the orientation control by the application of such magnetic flux is called "magnetic field orientation". Also, the orientation before the magnetic flux application is random. In FIG. 5, for convenience of explanation, the flake shape of the graphite 66 in the orientation state before the magnetic flux application is described as "horizontal".

[0034] (Magnet Arrangement) As shown in FIG. 7, in the magnetic flux application device 60 of the present embodiment, the first and second magnetic flux forming portions 61, 62 each include a plurality of magnets 80 arranged side by side in the spreading direction of the electrode sheet 35N passing through the gap D between the first and second magnetic flux forming portions 61, 62. And, the magnetic flux application device 60 of the present embodiment is configured to use permanent magnets such as neodymium magnets as each of these magnets 80.

[0035] Specifically, as shown in FIG. 8, in the magnetic flux application device 60 of the present embodiment, each first magnet 81 disposed above the electrode sheet 35N has a second magnet 82 disposed below the corresponding electrode sheet 35N. Further, each set of magnet pairs 85 formed by these first magnets 81 and second magnets 82 has opposing surfaces 81s, 82s with different polarities and are disposed opposite to each other. And, the magnetic flux application device 60 of the present embodiment is configured to form the first and second magnetic flux forming portions 61, 62 in a state where these magnet pairs 85 are arranged in the spreading direction of the electrode sheet 35N.

[0036] More specifically, in the magnetic flux applying device 60 of the present embodiment, each magnet 80 constituting the first and second magnetic flux forming portions 61 and 62 has a cubic shape. That is, these first magnet 81 and second magnet 82 each have square opposing surfaces 81s and 82s. Further, in each set of magnet pairs 85, the cubic shapes of the first magnet 81 and the second magnet 82 coincide in a plan view. That is, these first magnet 81 and second magnet 82 are arranged to face each other in the vertical direction with their opposing surfaces 81s and 82s facing each other. And in the magnetic flux applying device 60 of the present embodiment, the gap δ between the opposing surface 81s of the first magnet 81 and the opposing surface 82s of the second magnet 82 is the gap D between the first and second magnetic flux forming portions 61 and 62.

[0037] Also, as shown in FIGS. 8 and 9, the magnetic flux applying device 60 of the present embodiment has first and second magnet pairs 85sn and 85ns in which the combinations of polarities applied to the opposing surface 81s of the first magnet 81 and the opposing surface 82s of the second magnet 82 are different. Specifically, in the first magnet pair 85sn, the opposing surface 81s of the first magnet 81 is an "S pole" and the opposing surface 82s of the second magnet 82 is an "N pole". Also, in the second magnet pair 85ns, the polarity of the opposing surface 81s of the first magnet 81 is an "N pole" and the opposing surface 82s of the second magnet 82 is an "S pole". And the magnetic flux applying device 60 of the present embodiment is configured such that the first and second magnet pairs 85sn and 85ns are arranged in an alternating so-called staggered arrangement state to form the first and second magnetic flux forming portions 61 and 62 extending in the extending direction of the electrode sheet 35N.

[0038] That is, in the magnetic flux applying device 60 of the present embodiment, the first and second magnet pairs 85sn and 85ns generate magnetic fluxes in opposite directions based on the combinations of polarities applied to their opposing surfaces 81s and 82s. And thereby, it is possible to arrange these first and second magnet pairs 85sn and 85ns in a state where they are in contact with each other.

[0039] As shown in FIGS. 7 and 10, the magnetic flux application device 60 of the present embodiment utilizes this to arrange each pair of adjacent magnet pairs 85 in a state where they are in contact with each other, along the spreading direction of the electrode sheet 35N passing through the gap δ between their opposing surfaces 81s, 82s. Specifically, each of these magnet pairs 85 is arranged in contact with each other without a gap in the first and second arrangement directions L1, L2 that are orthogonal to each other along the spreading direction of the electrode sheet 35N, based on the cubic shape of each magnet 80. And the magnetic flux application device 60 of the present embodiment can thereby increase the arrangement density of each magnet pair 85 forming the first and second magnetic flux forming portions 61, 62.

[0040] (Magnet holding structure) More specifically, as shown in FIG. 11, the magnetic flux application device 60 of the present embodiment includes a first yoke 91 to which each first magnet 81 constituting the first magnetic flux forming portion 61 is fixed, and a second yoke 92 to which each second magnet 82 constituting the second magnetic flux forming portion 62 is fixed. In the magnetic flux application device 60 of the present embodiment, these first yoke 91 and second yoke 92 are configured using an iron-based magnetic metal. Also, these first yoke 91 and second yoke 92 are arranged spaced apart in the vertical direction in a state where each first magnet 81 held by the first yoke 91 and each second magnet 82 held by the second yoke 92 face each other. Further, in the magnetic flux application device 60 of the present embodiment, in this state, a spacer 93 made of a non-magnetic material such as resin is interposed between the first yoke 91 and the second yoke 92. And the magnetic flux application device 60 of the present embodiment is configured to stably hold the first magnet 81 and the second magnet 82 constituting each pair of magnet pairs 85, and to strengthen the magnetic flux formed in the gap δ between their opposing surfaces 81s, 82s.

[0041] (Tilt in the arrangement direction) Also, as shown in FIGS. 7, 10, 12, and 13, in the magnetic flux applying device 60 of the present embodiment, with respect to the passing direction L0 of the electrode sheet 35N passing through the gap δ of each magnet pair 85, the first and second array directions L1 and L2 have inclinations θ1 and θ2. Specifically, in the magnetic flux applying device 60 of the present embodiment, these inclinations θ1 and θ2 are set to "45°". Further, based on the inclinations θ1 and θ2 set in the respective array directions L1 and L2 of each magnet pair 85, a high magnetic flux density portion, that is, a highly oriented high-orientation region β is formed in the magnetic flux of each magnet pair 85 applied in a direction orthogonal to the electrode sheet 35N passing through the gap δ. And the magnetic flux applying device 60 of the present embodiment is configured such that, thereby, the negative electrode active material 65N contained in the negative electrode composite material 37N is strongly oriented in this high-orientation region β.

[0042] Specifically, as shown in FIGS. 8, 10, and 12, when each magnet 80 constituting each magnet pair 85 has a shape having a corner 80x that forms rectangular opposing surfaces 81s and 82s, the magnetic flux density in the vicinity of this corner 80x tends to be high. Further, since the array directions L1 and L2 of each magnet pair 85 have inclinations θ1 and θ2 with respect to the passing direction L0 of the electrode sheet 35N, a portion where the magnetic balance in the vicinity of the corner 80x of the magnet 80 is disrupted is formed at the end position 95e of the magnet pair group 95. And this portion where the magnetic balance is disrupted becomes a high-orientation region β having a high magnetic flux density in a direction orthogonal to the electrode sheet 35N passing through the gap δ of the magnet pair 85.

[0043] Specifically, as shown in FIGS. 12 and 14, at the inner position 95c of the magnet pair group 95, the corners 80xa and 80xb of different polarities are arranged adjacent to each other in the same number. And thereby, the balance of the magnetic balance in the vicinity of each of these corners 80xa and 80xb is maintained.

[0044] On the other hand, as shown in FIGS. 12 and 15, at the exit positions γ of the first and second magnetic flux forming portions 61 and 62 that are the end positions 95e of the magnet pair group 95, a portion is formed in which the corner portions 80xa having one polarity are arranged alone. And thereby, due to the imbalance of the magnetic balance in the vicinity of the corner portion 80xa arranged alone, a highly oriented region β is formed at the end position 95ea of this portion.

[0045] Also, as shown in FIGS. 12 and 16, at the exit positions γ of the first and second magnetic flux forming portions 61 and 62 that are the end positions 95e of the magnet pair group 95, a portion is formed where the number of corner portions 80xb having the adjacent other polarity is smaller than the number of corner portions 80xa having one polarity. And also for the end position 95eb of this portion, a highly oriented region β is formed due to the imbalance of the magnetic balance in the vicinity.

[0046] Furthermore, as shown in FIGS. 7, 10, and 12, in the magnetic flux applying device 60 of the present embodiment, as described above, each of the arrangement directions L1 and L2 of each magnet pair 85 has an inclination θ1, θ2 of "45°". That is, in each of these magnet pairs 85, the diagonal direction of the opposing surfaces 81s and 82s coincides with the passing direction L0 of the electrode sheet 35N. Specifically, one side of the diagonal direction coincides. And the magnetic flux applying device 60 of the present embodiment is configured to form a plurality of highly oriented regions β spaced at equal intervals in the width direction of the electrode sheet 35N passing through the gap δ of each magnet pair 85.

[0047] That is, as shown in FIG. 13, by forming the highly oriented region β as described above, in this highly oriented region β, the negative electrode active material 65N contained in the negative electrode composite material 37N becomes more significantly in a state along the magnetic flux in the direction orthogonal to the electrode sheet 35N. And thereby, higher battery performance can be ensured.

[0048] In addition, when the negative electrode active material 65N in the negative electrode composite material 37N is uniformly and strongly oriented (see FIG. 6), there is a problem that the contact area with the base material 36N serving as the current collector 31 decreases. Further, during drying of the negative electrode composite material 37N, the negative electrode active material 65N in the negative electrode composite material 37N tends to move to the surface side. And due to the occurrence of such migration, the adhesion of the negative electrode active material layer 32N formed by the negative electrode composite material 37N coated on the base material 36N may decrease.

[0049] In this regard, in the secondary battery 1 of the present embodiment, by setting the highly oriented region β, it is possible to relatively suppress the orientation by the magnetic flux applied in the direction orthogonal to the electrode sheet 35N for other portions. That is, for portions other than the highly oriented region β, the negative electrode active material 65N in the negative electrode composite material 37N can be prevented from being excessively oriented in the direction orthogonal to the electrode sheet 35N. And the secondary battery 1 of the present embodiment is configured to thereby ensure an appropriate contact state of the negative electrode active material 65N with the base material 36N, suppress the occurrence of migration, and ensure high adhesion of the negative electrode active material layer 32N laminated on the base material 36N.

[0050] (Reference Example) In the magnetic flux applying device 100 of the reference example shown in FIGS. 17 to 19, the first magnet 101 and the second magnet 102 having wide rectangular opposing surfaces 101s and 102s extending in the width direction of the electrode sheet 35N are used to form the first and second magnetic flux forming portions 111 and 112. That is, also in the magnetic flux applying device 100 of this reference example, different polarities are given to the opposing surfaces 101s and 102s of these first magnet 101 and second magnet 102. Further, these first magnet 101 and second magnet 102 are arranged with a gap in the vertical direction in a state where their opposing surfaces 101s and 102s face each other to form a magnet pair 115. And the magnetic flux applying device 100 of this reference example is configured to arrange a plurality of magnet pairs 115 side by side along the passing direction L0 of the electrode sheet 35N passing through the gap δ between the opposing surfaces 101s and 102s.

[0051] (Magnetic Flux Density Measurement of Reference Example) Figures 20 to 22 are graphs showing the results of measuring the magnetic flux density of each magnet pair 115 constituting the magnetic flux applying device 100 of the reference example. In this magnetic flux density measurement test, both the first magnet 101 and the second magnet 102 constituting the magnet pair 115 have a substantially flat rectangular parallelepiped shape extending in the vertical direction and the width direction of the electrode sheet 35N. Also, for these first magnet 101 and second magnet 102, the dimensions in the "width direction of the electrode sheet 35N", the vertical direction, and the "passing direction of the electrode sheet 35N" are "150 mm × 25 mm × 5 mm". Further, in this measurement test, the magnetic flux density was measured when the gap δ between the first magnet 101 and the second magnet 102, the measurement position Z of the magnetic flux density, and the arrangement interval X of each magnet pair 115 arranged along the passing direction L0 of the electrode sheet 35N were changed (see FIGS. 18 and 19). Note that the measurement position Z is a position spaced upward from the central position on the lower opposing surface 102s. The units of these gap δ, measurement position Z, and arrangement interval X are also each "millimeter". And the unit of the magnetic flux density is "millitesla".

[0052] As shown in each figure, the magnetic flux density of the magnet pair 115 becomes higher as the measurement position Z is closer to either of the opposing surfaces 101s, 102s. Also, the magnetic flux density becomes higher as the gap δ between the opposing surfaces 101s, 102s is smaller. And the magnetic flux density becomes higher as the arrangement interval X of each magnet pair 115 is larger.

[0053] Furthermore, when the test results of measuring the magnet pair 115 alone are shown by a two-dot chain line in each figure, as the arrangement interval X thereof increases, a value closer to the test results of the magnet pair alone is obtained (X = 10 is the best). That is, when the arrangement interval X of each magnet pair 115 is small, magnetic flux flows between the adjacent magnet pairs 115, 115. As a result, it is presumed that the magnetic flux between the first magnet 101 and the second magnet 102 in each magnet pair 115, that is, the magnetic flux in the direction orthogonal to the electrode sheet 35N passing through the gap δ between the opposing surfaces 101s, 102s becomes small. And from the above test results, in the magnetic flux applying device 100 of the reference example, it was confirmed that it is preferable to set the arrangement interval X of each magnet pair 115 to a certain value or more, for example, "5 mm" or more (X ≧ 5).

[0054] (Measurement of magnetic flux density in the embodiment) FIG. 23 shows the test results when the magnetic flux density of each magnet pair 85 of the magnetic flux applying device 60 of the present embodiment is measured in the same manner as in the above reference example. In the case of the magnetic flux applying device 60 of the present embodiment, based on the cubic shape of each magnet 80, each magnet pair 85 is arranged in contact in the first and second arrangement directions L1, L2 along the spreading direction of the electrode sheet 35N passing through the gap δ between the opposing surfaces 81s, 82s. For this reason, the arrangement interval X of each magnet pair 85 is "0" (X = 0). Furthermore, the dimensions of each magnet 80 in the "width direction of the electrode sheet 35N", the vertical direction, and the "passing direction of the electrode sheet 35N" are "10 mm × 10 mm × 10 mm". And as shown in the figure, also in this embodiment, the magnetic flux density of the magnet pair 85 becomes higher as the measurement position Z is closer to either of the opposing surfaces 81s, 82s, and it is confirmed that the magnetic flux density becomes higher as the gap δ between these opposing surfaces 81s, 82s is smaller.

[0055] (Operation) Also, in the case of the magnetic flux application device 60 of the present embodiment, by arranging each magnet pair 85 in contact, the arrangement space required to secure the magnetic flux amount necessary for orienting the negative electrode active material 65N in the negative electrode composite material 37N applied to the electrode sheet 35N becomes smaller. And thereby, the time required for the electrode sheet 35N to pass through the magnetic flux application device 60, that is, the orientation time, is shortened.

[0056] Furthermore, by arranging a large number of magnet pairs 85 with small areas of the opposing surfaces 81s, 82s, it becomes possible to reduce the magnetic attraction force per each magnet pair 85. For example, in the magnetic flux application device 100 of the reference example, when compared with the first magnet 101 and the second magnet 102 constituting each magnet pair 115, in the magnetic flux application device 60 of the present embodiment, the magnetic attraction force of each magnet pair 85 becomes about "1 / 10". For this reason, it is easy to handle each magnet 80 that forms a pair. Specifically, due to the magnetic attraction force, each magnet 80 does not accidentally stick together. As a result, even if a small value is set for the gap δ between the opposing surfaces 81s, 82s, it becomes possible to stably hold the first magnet 81 and the second magnet 82 constituting each set of magnet pairs 85. And thereby, it becomes possible to apply a stronger magnetic flux to the electrode sheet 35N passing through the gap δ between the opposing surfaces 81s, 82s.

[0057] For example, as shown in FIG. 24, in the case of the magnetic flux application device 100 of the above reference example, since the areas of the opposing surfaces 101s, 102s are large, the magnetic attraction force between the first magnet 101 and the second magnet 102 constituting each magnet pair 115 tends to be strong. For this reason, in consideration of the strength of the magnetic attraction force, it is preferable that the gap δ between the opposing surfaces 101s, 102s be "5 mm" or more.

[0058] On the other hand, in the magnetic flux applying device 60 of the present embodiment, for example, in the case of the above-described embodiment, it is possible to increase the magnetic flux density and set the gap δ between the opposing surfaces 81s and 82s to a value smaller than "5 mm". In FIG. 24, each point surrounded by a broken line represents the measurement result of the embodiment. As a result, even when the negative electrode composite material 37N coated on the electrode sheet 35N has a higher viscosity, it is possible to appropriately orient the negative electrode active material 65N in the coated negative electrode composite material 37N.

[0059] For example, assuming that the upper limit of the viscosity suitable for "magnetic field orientation" in the magnetic flux applying device 100 of the reference example is "5000 mPa·s", the magnetic flux applying device 60 of the present embodiment can appropriately perform "magnetic field orientation" even when the viscosity of the negative electrode composite material 37N is "7000 mPa·s". Further, in this case, assuming that the orientation time when using the magnetic flux applying device 100 of the reference example is about "3.8 seconds", the orientation time in the magnetic flux applying device 60 of the present embodiment is shortened to about "1.3 seconds". Also, the orientation time of about "3.8 seconds" when using the magnetic flux applying device 100 of the reference example is a value obtained by considering the passing time of the arrangement interval X (the passing time of the magnet portion is about "1.9 seconds"). When this is converted into the moving distance of the electrode sheet 35N, for example, assuming that the moving speed of the electrode sheet 35N is "1 m / second", it is possible to suppress the arrangement space of each magnet pair 85 by the amount of the orientation time difference.

[0060] Next, the effects of the present embodiment will be described. (1) The manufacturing apparatus 50 of the secondary battery 1 includes a magnetic flux applying device 60 having a plurality of sets of magnet pairs 85 each consisting of a pair of magnets 80 having opposing surfaces 81s and 82s with different polarities and arranged to face each other. In this magnetic flux applying device 60, as the electrode sheet 35N passes through the gap δ between the opposing surfaces 81s and 82s of each magnet pair 85, the orientation of the negative electrode active material 65N contained in the negative electrode composite material 37N coated on the electrode sheet 35N is controlled. Also, each magnet pair 85 is arranged side by side in first and second arrangement directions L1 and L2 that intersect each other along the spreading direction of the electrode sheet 35N passing through the gap δ between the opposing surfaces 81s and 82s. And each set of magnet pairs 85 adjacent to each other in each arrangement direction L1 and L2 is arranged in contact with each other having magnetic flux directions opposite to each other.

[0061] According to the above configuration, by arranging each magnet pair 85 in contact, it is possible to significantly reduce the arrangement space for securing the amount of magnetic flux necessary for orienting the negative electrode active material 65N in the negative electrode composite material 37N coated on the electrode sheet 35N. And thereby, the time required for the electrode sheet 35N to pass through the magnetic flux applying device 60, that is, the orientation time of the electrode sheet 35N can be shortened.

[0062] Also, by arranging a large number of magnet pairs 85 with small areas of the opposing surfaces 81s and 82s, the magnetic attraction force per magnet pair 85 can be reduced. And thereby, it is possible to easily handle each pair of magnets 80.

[0063] Furthermore, taking advantage of this, in a state where a small value is set for the gap δ between the opposing surfaces 81s and 82s, the first magnet 81 and the second magnet 82 constituting each magnet pair 85 can be stably held. Also, the magnetic flux density of each magnet pair 85 can be set high. And thereby, a stronger magnetic flux can be applied to the electrode sheet 35N passing through the gap δ between the opposing surfaces 81s and 82s. As a result, even when the negative electrode composite material 37N coated on the electrode sheet 35N has a higher viscosity, the negative electrode active material 65N in the coated negative electrode composite material 37N can be appropriately oriented.

[0064] (2) The opposing surfaces 81s and 82s of each magnet pair 85 are square. According to the above configuration, it is easy to arrange each magnet pair 85 in the first and second arrangement directions L1 and L2 in a contact state. And thereby, the application of magnetic flux to the electrode sheet 35N can be performed efficiently.

[0065] (3) The first and second arrangement directions L1 and L2 have inclination angles θ1 and θ2 with respect to the passing direction L0 of the electrode sheet 35N. According to the above configuration, at the end position 95e of the magnet pair group 95 formed by each magnet pair 85, a portion where the magnetic balance near the corner 80x of the magnet 80 is disrupted is formed. And thereby, a highly oriented region β with a high magnetic flux density in a direction orthogonal to the electrode sheet 35N passing through the gap δ of the magnet pair 85 can be formed.

[0066] That is, in the highly oriented region β, the negative electrode active material 65N contained in the negative electrode composite material 37N becomes more significantly in a state along the magnetic flux in the direction orthogonal to the electrode sheet 35N. And thereby, higher battery performance can be ensured.

[0067] Also, when the negative electrode active material 65N in the negative electrode composite material 37N is uniformly and strongly oriented, the contact area with respect to the base material 36N that becomes the current collector 31 decreases. As a result, when the negative electrode composite material 37N is dried, the negative electrode active material 65N in the negative electrode composite material 37N easily moves to the surface side, and there is a possibility that the adhesion of the negative electrode active material layer 32N formed by the negative electrode composite material 37N coated on the base material 36N decreases.

[0068] However, according to the above configuration, for the portion other than the highly oriented region β, the orientation can be suppressed to be relatively low, and an appropriate contact state of the negative electrode active material 65N with respect to the base material 36N can be ensured. And thereby, the movement to the surface side during drying can be suppressed, and a high adhesion of the negative electrode active material layer 32N laminated on the base material 36N can be ensured.

[0069] (4) The diagonal direction of each opposing surface coincides with the passing direction L0 of the electrode sheet. According to the above configuration, in the width direction of the electrode sheet 35N passing through the gap δ of each magnet pair 85, a plurality of highly oriented regions β spaced at equal intervals can be formed. And thereby, more effectively, based on the density of the magnetic flux applied to the electrode sheet 35N, a decrease in the adhesive force caused by the surface-side movement of the negative electrode active material 65N occurring during drying of the negative electrode composite material 37N can be suppressed.

[0070] (5) Each of the magnets 80 has a cubic shape. According to the above configuration, the opposing surfaces 81s, 82s of each magnet pair 85 become square. And thereby, in the first and second arrangement directions L1, L2 orthogonal to each other, each magnet pair 85 can be arranged in contact with each other without a gap. And thereby, the application of magnetic flux to the electrode sheet 35N can be performed more efficiently.

[0071] Note that the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0072] · The dimensions of the magnets 80 constituting each magnet pair 85 may be arbitrarily changed. And also, the gap δ between the opposing surfaces 81s, 82s may be arbitrarily changed. · The number of each magnet pair 85 arranged side by side in the first and second arrangement directions L1, L2 may be arbitrarily changed. It is only necessary to ensure the amount of magnetic flux required to orient the negative electrode active material 65N in the negative electrode composite material 37N coated on the electrode sheet 35N. However, regarding the number of magnet pairs 85 arranged in the width direction of the electrode sheet 35N, a larger number is preferable.

[0073] For example, as shown in the reference example of FIG. 25, when two first magnets 101 and two second magnets 102 each having a substantially flat cuboid shape are arranged side by side in the width direction of the electrode sheet 35N, a problem occurs in the portion where the magnet pairs 115, 115 are adjacent to each other in the width direction of the electrode sheet 35N. That is, in this portion, the magnet pairs 115, 115 having opposing surfaces 101s, 102s with different polarities are arranged in contact with each other, and magnetic flux is formed in the adjacent direction, that is, in the width direction of the electrode sheet 35N. And when the contact portions of such adjacent magnet pairs 115, 115 are few, there is a problem that this portion stands out as a portion having a low magnetic flux density in a direction orthogonal to the electrode sheet 35N passing through the gap δ of the magnet pair 115.

[0074] · The thickness of the negative electrode composite material 37N applied on the base material 36N may be arbitrarily set. Also, the viscosity of the negative electrode composite material 37N may also be arbitrarily changed. · In the above embodiment, each magnet 80 constituting the magnet pair 85 has a cubic shape. However, not limited to this, regarding the shape of each magnet 80, for example, even if the opposing surfaces 81s, 82s are square, a cuboid shape in which the length of each side of the square and the length in the vertical direction are different may be used. Also, regarding the shape of the opposing surfaces 81s, 82s, it is not necessarily limited to a square, and may be a rectangle. Further, the shape of each opposing surface 81s, 82s may be a rhombus or a trapezoid. Also, the shape of the opposing surfaces 81s, 82s may be a polygon other than a quadrilateral, or a rounded shape. And as long as the opposing surfaces 81s, 82s are provided, the shape of each magnet 80 does not necessarily have to be a hexahedron.

[0075] · In the above embodiment, the first and second arrangement directions L1, L2 have inclination angles θ1, θ2 of "45°" respectively with respect to the passing direction L0 of the electrode sheet 35N passing through the gap δ of each magnet pair 85. However, not limited to this, the inclination angle θ of each arrangement direction L1, L2 with respect to the passing direction L0 may be arbitrarily changed. And a configuration in which one of these first and second arrangement directions L1, L2 has no inclination with respect to the passing direction L0 of the electrode sheet 35N may be used.

[0076] ·In the above embodiment, by using the magnetic flux applying device 60, the orientation of the negative electrode active material 65N contained in the negative electrode composite material 37N coated on the electrode sheet 35N was controlled. And, as an example thereof, the case where the negative electrode active material 65N in the negative electrode composite material 37N is graphite 66 which is a hexagonal plate-shaped crystal having a flaky shape was illustrated. However, it is not limited thereto, and the shape of the negative electrode active material 65N to be "magnetic field oriented" is arbitrary. For example, the negative electrode active material 65N may be fibrous graphite 66. And, the negative electrode active material 65N to be "magnetic field oriented" may be in a lump shape in which particles of graphite 66 are aggregated. Incidentally, the larger the aspect ratio, the more easily it is affected by the "magnetic field orientation".

[0077] ·Furthermore, the magnetic flux applying device 60 may be used for the orientation of the conductive material contained in the negative electrode composite material 37N. And, in order to orient graphite 66 contained as a conductive material in the positive electrode composite material 37P coated on the electrode sheet 35P for the positive electrode 3, or a conductive fibrous carbon material such as carbon nanofiber (CNT), the magnetic flux applying device 60 may be used.

[0078] ·In the above embodiment, the electrode body 10 of the secondary battery 1 has a configuration as a wound body, but necessarily, the positive and negative electrode sheets 35P and 35N laminated with the separator 5 therebetween do not necessarily have to be wound. Further, the secondary battery 1 does not necessarily have to be a lithium ion secondary battery, and may be applied to other non-aqueous electrolyte secondary batteries. And, the terminal shapes of the positive electrode terminal 38P and the negative electrode terminal 38N may also be arbitrarily changed not limited to the shapes shown in FIG. 1.

[0079] Next, the technical idea that can be grasped from the above embodiment and the modification example will be described. (A) Each of the opposed surfaces is square. According to the above configuration, in the first and second arrangement directions orthogonal to each other, the magnet pairs can be arranged in contact with each other without a gap. And, thereby, the magnetic flux can be applied to the electrode sheet more efficiently.

[0080] (b) The inclination is 45 degrees. According to the above configuration, in the width direction of the electrode sheet, a plurality of highly oriented regions spaced at equal intervals can be formed.

Explanation of Reference Numerals

[0081] 1... Secondary battery 35N... Electrode sheet 37N... Negative electrode composite material 50... Manufacturing apparatus 60... Magnetic flux applying device 65N... Negative electrode active material 80... Magnet 81s, 82s... Opposing surfaces 85... Magnet pair δ... Gap L1... First array direction L2... Second array direction

Claims

1. A manufacturing apparatus for a secondary battery, comprising a pair of magnet pairs each composed of a pair of magnets having opposing surfaces with different polarities and arranged to face each other, wherein the orientation of the negative electrode active material contained in the negative electrode composite material coated on the electrode sheet is controlled by passing the electrode sheet through the gap between the opposing surfaces, comprising a plurality of sets of the magnet pairs arranged side by side in first and second arrangement directions intersecting each other along the spreading direction of the electrode sheet passing through the gap between the opposing surfaces, and the manufacturing apparatus for a secondary battery, wherein each set of the magnet pairs adjacent to each other in each arrangement direction is arranged in contact with each other with opposite magnetic flux directions.

2. The manufacturing apparatus for a secondary battery according to claim 1, wherein each of the opposing surfaces is rectangular.

3. The manufacturing apparatus for a secondary battery according to claim 2, wherein the first and second arrangement directions have an inclination with respect to the passing direction of the electrode sheet.

4. The diagonal direction of each of the opposing surfaces coincides with the passing direction of the electrode sheet The manufacturing apparatus for a secondary battery according to claim 3.

5. Each of the magnets has a cubic shape The manufacturing apparatus for a secondary battery according to any one of claims 1 to 4.

6. A magnetic flux applying device, comprising a pair of magnet pairs each composed of a pair of magnets having opposing surfaces with different polarities and arranged to face each other, wherein magnetic flux is applied to the electrode composite material coated on the electrode sheet by passing the electrode sheet through the gap between the opposing surfaces, comprising a plurality of sets of the magnet pairs arranged side by side in first and second arrangement directions intersecting each other along the spreading direction of the electrode sheet passing through the gap between the opposing surfaces, and the magnetic flux applying device, wherein each set of the magnet pairs adjacent to each other in each arrangement direction is arranged in contact with each other with opposite magnetic flux directions.

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