JP6154469B2 - Method for manufacturing electrode laminate - Google Patents

Description

  The present invention relates to a method for manufacturing an electrode laminate in a laminated battery such as a lithium ion battery.

  As a structure suitable for a relatively large capacity lithium-ion battery, etc., it has a flat shape in which an electrode laminate formed by laminating a plurality of sheet-like electrodes and separators is sealed together with an electrolyte in an outer package made of a laminate film or the like. A laminated battery is known.

  Patent Documents 1 and 2 describe a method for manufacturing an electrode laminate in this type of battery, in which electrodes (positive electrode and negative electrode) made of metal foil and a separator are transferred one by one using an adsorption-type hand. Thus, these are alternately stacked. That is, the electrodes and separators to be stacked are sequentially supplied to each supply stage in a state of being cut into a predetermined shape, and stacking is performed by the suction type hand being conveyed from the supply stage to each stacking stage. . Therefore, the suction-type hand repeats the movement between the supply stage and the stacking stage, the suction of the workpiece (sheet-like electrode or separator) on the supply stage, and the release of the workpiece on the stacking stage. .

  In the method of manufacturing an electrode laminate in which sheet-like separators are stacked using an adsorption-type hand as described above, static electricity is generated due to friction with the separator and air, etc., due to continuous repeated operation of the adsorption-type hand, The suction type hand is charged. For this reason, when the suction type hand holding the separator by suction approaches the base in the stacking stage, a discharge spark is generated between the suction type hand and the base, and a minute hole is formed in the synthetic resin separator. There was a problem that.

  An object of the present invention is to reliably prevent the separator from being damaged by the charging of the suction type hand.

JP 2008-282756 A JP 2012-227130 A

  The present invention provides an electrode stacking stage on which a sheet-like electrode cut into a predetermined shape is placed via a suction-type hand along a pallet transport line, and a suction-type hand with a sheet-like separator cut into a predetermined shape. A separator stacking stage placed between the electrode stacking stage, the electrode stacking stage and the separator stacking stage, the electrode stacking stage and the electrode stacking stage, and the electrode stacking stage and the electrode stacking stage. In the method for manufacturing an electrode laminate in a laminated battery that is circulated through the separator lamination stage a plurality of times until a predetermined number is reached, the adsorption type hand in the separator lamination stage after an appropriate number of lamination treatments Including a static elimination step of performing static elimination.

  That is, in the present invention, a sheet-like electrode is placed on the pallet in the electrode lamination stage, and then a sheet-like separator is placed on the same pallet in the separator lamination stage. By repeating these processes, Electrodes and separators are alternately stacked on the substrate. In such a laminating process, the suction type hand in the separator laminating stage is gradually charged by repeating the repetitive operation. In the present invention, the static elimination is performed after an appropriate number of laminating processes. Therefore, discharge between the pallet causing damage to the separator is prevented.

In a preferred embodiment of the present invention, the adsorption-type hand includes a rectangular porous adsorption plate corresponding to the outer shape of the separator, and a rod-shaped ionizer having a length over one side of the porous adsorption plate. the reference, by moving the ionizer along the surface of the porous suction plate neutralizes the entire surface in contact with the separators including the four corners of the porous suction plate.

  According to the present invention, by providing the static elimination step, it is possible to prevent discharge between the suction type hand holding the separator and the pallet, and to avoid the phenomenon of the separator perforation due to the discharge spark.

The perspective view which shows an example of a laminated structure battery. Similarly sectional drawing. Process explanatory drawing which shows the outline of the manufacturing process of the laminated structure battery which concerns on this invention. The top view which shows a lamination apparatus roughly. The top view of the pallet used with this lamination apparatus. The top view of the lamination robot for separators. Similarly front view. Explanatory drawing which showed the relationship between the outer shape of a porous adsorption | suction plate, and a pallet. The perspective view of an ionizer. Explanatory drawing which shows the static elimination work using an ionizer.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  First, based on FIG. 1 and FIG. 2, an example of the laminated battery 1 to be manufactured according to the present invention will be briefly described. This laminated structure battery 1 is, for example, a lithium ion secondary battery, and has a flat rectangular external shape as shown in FIG. 1, and is formed of a conductive metal foil at one end in the longitudinal direction. A pair of terminals 2 and 3 are provided.

  As shown in FIG. 2, the laminated battery 1 is a battery in which a rectangular electrode laminate 4 is accommodated in an exterior body 5 made of a laminate film together with an electrolytic solution. The electrode laminate 4 is composed of the same sheet-like positive electrodes 12 and negative electrodes 13 that are alternately laminated via sheet-like separators 11, for example, 18 negative electrodes 13, 17 positive electrodes 12, and these 34 separators 11 in between. 2 are not accurate and are exaggerated or omitted for explanation.

  The positive electrode 12 is obtained by coating a positive electrode active material layer 12b on both surfaces of a positive electrode current collector 12a made of a metal foil such as an aluminum foil. The positive electrode active material layer 12b is obtained by applying a mixture of a positive electrode active material made of a lithium metal oxide, a conductive aid such as carbon black, and a binder to the main surface of the positive electrode current collector 12a, and drying and It is formed by rolling.

  The negative electrode 13 is obtained by forming a negative electrode active material layer 13b on both surfaces of a negative electrode current collector 13a made of a metal foil such as a copper foil. The negative electrode active material layer 13b is formed by applying a negative electrode active material such as amorphous carbon or graphite mixed with a binder to the main surface of the negative electrode current collector 13a, and drying and rolling.

  A part of the longitudinal edge of the negative electrode current collector 13 a extends as an extension that does not include the negative electrode active material layer 13 b, and the tip thereof is joined to the negative electrode terminal 3. Although not shown in FIG. 2, similarly, a part of the longitudinal edge of the positive electrode current collector 12 a extends as an extension portion that does not include the positive electrode active material layer 12 b, and the tip thereof is the positive electrode. It is joined to the terminal 2.

  The separator 11 has a function of preventing a short circuit between the positive electrode 12 and the negative electrode 13 and simultaneously holding an electrolyte. For example, the separator 11 is made of a fine polyolefin resin such as polyethylene (PE) or polypropylene (PP). It consists of a porous film, and when an overcurrent flows, it has a function of blocking the current by closing the pores of the layer due to the heat generation.

  The positive electrode 12, the negative electrode 13 and the separator 11 are fixed by a tape (not shown) in a state where a predetermined number of layers are stacked, and are integrated as an electrode stack 4.

  The outer package 5 that accommodates the electrode laminate 4 together with the electrolytic solution is, for example, a three-layer structure in which a synthetic resin thermal fusion layer is laminated on the inner side of an aluminum foil, and a synthetic resin protective layer is laminated on the outer side It consists of a laminated film having a structure. The outer package 5 has a two-sheet structure of one laminate film disposed on the lower surface side of the electrode laminate 4 in FIG. 2 and another laminate film disposed on the upper surface side. It has a configuration in which the four sides around the two laminate films are superposed and heat-sealed to each other.

  A pair of terminals 2 and 3 positioned on the short side of the laminated battery 1 having a rectangular shape are drawn out through the bonding surface of the laminate film when the laminate film is heat-sealed. In the illustrated example, a pair of terminals 2 and 3 are arranged side by side on the same edge, but the positive terminal 2 is arranged on one edge and the negative terminal 3 is arranged on the other edge. It is also possible to do so.

  FIG. 3 is a process explanatory diagram showing an outline of the manufacturing process of the laminated battery 1 described above.

  In the positive electrode forming step 21, the slurry kneaded with the above-described positive electrode active material and the like is intermittently coated on a predetermined range of the surface of the continuous aluminum foil in a strip shape, and dried and rolled, so that a large number of rectangular shapes are formed. This is a step of manufacturing a belt-like positive electrode material provided with the positive electrode active material layer 12b. This positive electrode material is brought into the next laminating step 24 while being wound in a roll shape, and is cut into a predetermined length, that is, the length of each sheet-like positive electrode 12 in the laminating step 24. In addition, the width | variety of a roll-shaped positive electrode material respond | corresponds to the dimension of the short side of the sheet-like positive electrode 12, and it cuts for every dimension of a long side.

  In the negative electrode forming step 22, as in the positive electrode forming step 21, the slurry kneaded with the negative electrode active material and the like is intermittently coated on a predetermined range of the surface of the copper foil that is continuous in a strip shape, and is dried and rolled. This is a step of manufacturing a strip-shaped negative electrode material having a large number of rectangular negative electrode active material layers 13b. This negative electrode material is brought into the next laminating step 24 in a state wound in a roll shape, and is cut into a predetermined length, that is, a length dimension of each sheet-like negative electrode 13 in the laminating step 24. The width of the roll-shaped negative electrode material also corresponds to the short side dimension of the sheet-shaped negative electrode 13.

  The separator forming step 23 is a step of manufacturing a separator material that is continuous in a strip shape using a synthetic resin material. This separator material is also brought into the next laminating step 24 while being wound in a roll shape, and is cut into individual sheet-like separators 11 in the laminating step 24. The width of the roll separator material corresponds to the short side dimension of the sheet separator 11.

  In the laminating step 24 which is the main part of the present invention, the negative electrode 13, the separator 11, the positive electrode 12, and the positive electrode material, the negative electrode material, and the separator material wound in a roll shape are cut into individual sheet shapes, respectively. The separators 11 and the negative electrodes 13 are sequentially stacked in an alternating order. In the stacking step 24, as will be described later, the pallet is circulated along a predetermined conveyance line, and the sheets (the negative electrode 13, the separator 11, and the positive electrode 12) are sequentially placed on the pallet by the stacking robot. Is done. Here, in the present invention, in the laminating step 24, a static eliminating step 30 for performing static elimination of the suction type hand of the separator laminating robot is additionally performed.

  When a predetermined number of layers are completed in the stacking step 24, the electrode stack 4 is transported from the pallet to the next fixing step 25. In the fixing step 25, the electrode laminate 4 is integrally fixed using a fixing tape extending in the stacking direction of the electrode laminate 4.

  In the next laminate bonding step 26, the electrode laminate 4 fixed integrally is disposed between two laminate films serving as the exterior body 5, and the periphery is heat-sealed leaving the electrolyte solution inlet.

  And in the liquid injection process 27, the laminated structure battery 1 is completed by inject | pouring electrolyte solution and sealing an electrolyte solution injection port. The laminated battery 1 is further subjected to aging for a predetermined period in the aging process 28 after initial charging, and then sent to the inspection process 29 for various inspections.

  FIG. 4 schematically shows the configuration of the laminating apparatus 31 used in the laminating step 24. The laminating apparatus 31 has a linear pallet conveying conveyor 33 composed of a friction conveyor that sequentially conveys the pallets 32 shown in detail in FIG. 5, and separator laminating stages at four locations along the conveying line composed of the conveyor 33. 34 is arranged. Furthermore, the negative electrode lamination stage 35 is arrange | positioned at two places of a conveyance line, and the positive electrode lamination stage 36 is arrange | positioned in two more places. These stages are arranged in accordance with the stacking order of the sheet materials in the electrode stack 4, and accordingly, in order from the entrance side of the pallet transport conveyor 33, the negative electrode stacking stage 35, the separator stacking stage 34, the positive electrode stacking stage 36, Eight lamination stages are arranged in the order of the separator lamination stage 34, the negative electrode lamination stage 35, the separator lamination stage 34, the positive electrode lamination stage 36, and the separator lamination stage 34.

  The separator stacking stage 34 is provided with a separator supply unit 38 that supplies the sheet-like separators 11 one by one. The separator supply unit 38 is set with the separator material wound in the above-described roll shape, and the separator material stage 38 a (FIG. 6) adjacent to the separator stacking stage 34 is used to sequentially feed the strip-shaped separator material. The sheet-like separator 11 is sequentially supplied one by one on the temporary placement stage 38a. Then, the separator 11 in the form of one sheet is conveyed onto the pallet 32 stopped on the separator stacking stage 34 by a stacking robot 51 (see FIGS. 6 and 7) described later. Separator supply sections 38 provided individually on the four separator stacking stages 34 are arranged on one side of the pallet transport conveyor 33.

  Similarly, the negative electrode stacking stage 35 and the positive electrode stacking stage 36 are respectively provided with a negative electrode supply unit 39 to a positive electrode supply unit 40 for supplying the sheet-like negative electrode 13 to the positive electrode 12 one by one. The negative electrode supply unit 39 is configured to set the negative electrode material wound in the above-described roll shape. A negative electrode temporary placement stage (not shown) adjacent to the negative electrode stacking stage 35 is used to sequentially feed the strip-shaped negative electrode material. The sheet-like negative electrodes 13 are sequentially supplied one by one on the temporary placement stage by cutting the sheet into predetermined dimensions. Then, this single sheet of negative electrode 13 is conveyed onto a pallet 32 stopped on the negative electrode stacking stage 35 by the same stacking robot as that for stacking separators. The positive electrode supply unit 40 has the same configuration, and supplies sheet-like positive electrodes 12 one by one from a roll-shaped positive electrode material, and the positive electrode 12 of the pallet 32 stopped on the positive electrode lamination stage 36 by a lamination robot. Transported up. The negative electrode supply unit 39 and the positive electrode supply unit 40 are respectively arranged on the other side of the pallet transport conveyor 33 (that is, the side opposite to the separator supply unit 38).

  The pallet 32 is made of, for example, an aluminum alloy. As shown in FIG. 5, the pallet 32 has a substantially rectangular plate shape, and has a sheet-like workpiece (the negative electrode 13 and the separator 11 in the central laminated region 41 indicated by a virtual line. The positive electrode 12) is placed and sequentially stacked. Clamps 42 are provided at positions corresponding to the four corners of the laminated region 41 to hold the laminated workpieces (in other words, the electrode laminate 4 in the middle of lamination) in the lamination direction. Each clamp 42 has a shape in which an arm 42b protrudes every 90 ° around the rotation shaft 42a. On each of the stacked stages 34, 35, 36, the clamp provided on each of the stacked stages 34, 35, 36. By a drive mechanism (not shown), it is rotated by 90 ° while moving up and down in a manner interlocked with the lamination of the sheet-like workpieces.

  That is, while the pallet 32 is moving, the clamps 42 are biased downward by the spring force, and the arm 42b approaching the stacking region 41 presses the electrode stack 4 in the middle of stacking onto the pallet 32. Yes. Then, in each of the stacking stages 34, 35, and 36, the next sheet-like workpiece (the negative electrode 13, the separator 11, and the positive electrode 12) is placed by the stacking robot while the arm 42 b holds the electrode stack 4. At this time, the four corners of the sheet-like workpiece ride on the arms 42b of the clamps 42, respectively, and thus the four corners are temporarily lifted upward as compared with the central portion of the sheet-like workpiece. And the clamp 42 rotates 90 degrees, raising / lowering up and down under the state which the lamination | stacking robot is pressing the electrode laminated body 4. FIG. As a result, the arm 42b that has pressed the electrode laminate 4 until then is pulled out in the rotational direction, and the next another arm 42b puts the electrode laminate 4 on the pallet 32 together with the newly laminated sheet-like workpiece. Press down. Thereby, a large number of sheet-like works can be sequentially stacked while avoiding misalignment.

  Each pallet 32 is individually conveyed in the direction of arrow F in FIG. 5 by a pallet conveyance conveyor 33 formed of a friction conveyor. The long side of the laminated region 41 having a rectangular shape (that is, the long side of the sheet-like workpiece (the negative electrode 13, the separator 11, the positive electrode 12)) is orthogonal to the conveying direction. In the negative electrode supply unit 39 and the positive electrode supply unit 40 of FIG. 4 described above with respect to the conveyance direction of the pallet 32, the negative electrode material and the positive electrode material continuous in a strip shape are orthogonal to the conveyance line as indicated by arrows D1 and D2. Supplied in the direction of Accordingly, the individually cut sheet-like negative electrode 13 and positive electrode 12 do not need to change their directions, and are transferred in parallel on the pallet 32. On the other hand, in the separator supply unit 38, a strip-like separator material is supplied in parallel to the transport line as indicated by an arrow D3 in FIG. Accordingly, the individually cut sheet-like separator 11 is transferred onto the pallet 32 while changing the direction of 90 ° by the laminating robot 51.

  Although not shown in FIG. 4, a pallet return conveyor (not shown) is provided above the transfer line including the stacking stages 34, 35, and 36 in parallel with the transfer line. This pallet reflux conveyor is also composed of a friction conveyor, and conveys the pallet 32 in the opposite direction (the direction from the right side to the left side in FIG. 4) of the conveyance line including the stacking stages 34, 35, and 36. A lifter 45 for transferring the pallet 32 from the lower conveyance line to the upper pallet return conveyor is provided at the end point of the transfer line, and the pallet 32 is moved from the upper pallet return conveyor at the start point of the transfer line. A similar lifter 46 is provided for transfer to the lower transport line.

  Accordingly, each pallet 32 passes through the lower conveyance line and is sequentially laminated at each of the lamination stages 34, 35, 36, and then again through the lifter 45, the pallet reflux conveyor and the lifter 46, the first negative electrode lamination. Return to stage 35. In this way, one pallet 32 circulates through a loop composed of the conveyance line and the pallet return conveyor a plurality of times until the predetermined number of layers described above is completed. Then, the pallet 32 on which the predetermined number of layers are completed is transported to the next fixing step 25 as shown by an arrow F1 in FIG. 4, and the electrode stack 4 is fixed by the tape described above. Further, as shown by an arrow F2 in FIG. 4, an empty pallet 32 is appropriately replenished and a new stacking is started. Therefore, a plurality of pallets 32 are flowing in the stacking device 31 in a state where the number of stacks is different.

  6 and 7 show an example of a stacking robot 51 that transfers the sheet-like separator 11 from the separator supply unit 38 onto the pallet 32 of the separator stacking stage 34. The stacking robot 51 includes an arm 53 that reciprocates along a rail 52 that extends in a direction orthogonal to the transfer line, and a suction-type hand 55 that is attached to the tip of the arm 53 via a joint 54. ing. The suction-type hand 55 uses a rectangular porous suction plate 55a corresponding to the outer shape of the separator 11 as a suction portion, and is thin by performing suction on the entire surface of the flat porous suction plate 55a. The sheet-like separator 11 can be held without being damaged. As shown in FIG. 8, the porous adsorption plate 55a has a slightly smaller dimension than the outer shape of the separator 11 and is substantially arc-shaped at the four corners in order to avoid interference with the clamp 42 of the pallet 32. The notch part 56 is provided. Due to the notches 56, the clamps 42 can be rotated while the porous adsorption plate 55a is on the pallet 32.

  The operation of the stacking robot 51 is positioned in a state where the suction type hand 55 is lowered and cut on the separator temporary placement stage 38a of the separator supply unit 38 with the arm 53 moved to the separator supply unit 38 side. The separator 11 is held by suction. Next, the suction type hand 55 moves up and moves onto the pallet 32 of the separator stacking stage 34. During this movement, the orientation of the porous adsorption plate 55a rotates by 90 °. Then, the suction type hand 55 descends on the pallet 32, and the separator 11 is stacked on the electrode stack 4 in the middle of stacking. In this state, as described above, the clamps at the four corners rotate and the clamping operation is performed, so that suction by the suction type hand 55 is released in a state where the arm 42b of the clamp 42 fixes the uppermost separator 11. Thereafter, the suction type hand 55 moves up and moves onto the separator supply unit 38 again. In the present invention, the laminated robot is not limited to the linear movement type along the rail 52 as described above, but can be applied to various types such as a turning type robot.

  As a result of the suction-type hand 55 repeating the reciprocating operation and the contact with the separator 11 as described above, the porous suction plate 55a of the suction-type hand 55 is gradually charged. If this charging is left, a discharge spark is generated between the porous adsorption plate 55a holding the separator 11 and the pallet 32 made of aluminum alloy or the like, and a minute hole is made in the separator 11 made of synthetic resin. In general, this discharge is likely to occur at the four corners of the porous adsorption plate 55 a, particularly at the corners generated by the notches 56. Note that at least the surface of the porous suction plate 55a of the suction-type hand 55 that is in contact with the separator 11 is made of an insulator, and is gradually charged by repeated contact with the separator 11 that is also an insulator.

  In the present invention, in order to avoid the occurrence of discharge sparks due to such charging over time, after the appropriate number of stacking processes, neutralization is performed on the porous adsorption plate 55a as the neutralization process 30. This static elimination process 30 is performed manually by an operator using a rod-like ionizer 61 as shown in FIG. The ionizer 61 has a relatively thin rod shape with a rectangular cross section, and a plurality of ion outlets 62 are provided side by side on one side. Between the ion outlets 62, the surface of the porous adsorption plate 55a and A block-shaped cushioning material 63 for avoiding contact with the ion outlet 62 is provided.

  FIG. 10 shows the static elimination work using the ionizer 61. In this static elimination work, the suction type hand 55 of the stacking robot 51 receives the separator temporary placement stage 38a side of the separator supply unit 38 (that is, the sheet-like separator 11). The suction type hand 55 is raised from the separator temporary placement stage 38a. At this time, the laminating apparatus 31 is stopped, and the worker can access the separator supply unit 38 from the front side (that is, from the lower side in FIG. 4) toward the transport line. As shown in the drawing, one end of a rod-like ionizer 61 is held by a finger 65 and the ion blower outlet 62 is placed in an upward position and inserted between the porous adsorption plate 55a and the separator temporary placement stage 38a. Then, the rod-like ionizer 61 is moved in the lateral direction along the surface of the porous adsorption plate 55a, thereby eliminating the charge over the entire surface of the porous adsorption plate 55a. As can be understood from FIG. 6, the ionizer 61 is inserted along the short side direction of the porous adsorption plate 55a and moved in the long side direction. Therefore, the ionizer 61 has a length extending at least over the short side of the porous adsorption plate 55a. The static elimination operation is completed in one stroke or one reciprocation of the ionizer 61 from one end to the other end of the long side. As described above, discharge sparks are likely to be generated at the corners of the porous adsorption plate 55a. Therefore, it is particularly desirable to surely remove the charge from the four corners of the porous adsorption plate 55a and the range including the corners generated by the notches 56. The frequency of performing such static elimination work varies depending on various conditions. For example, if the number of times of stacking by one stacking robot 51 reaches about 300 to 4000 times, the charging voltage sandwiches the separator 11. There is no risk of exceeding the breakdown voltage, and therefore no discharge sparks are produced during the lamination process.

  The above-described static elimination work is performed for the stacking robots 51 in all the separator stacking stages 34. In the above embodiment, since the static elimination work is performed using the rod-like ionizer 61 when the suction type hand 55 is in the retracted position on the separator supply unit 38 side as described above, it is easy for the worker to access and the short time. The entire surface of the porous adsorption plate 55a can be reliably discharged in time. Further, since the ionizer 61 includes the block-shaped buffer material 63, the surface of the porous adsorption plate 55a is not damaged during the static elimination work.

  The lamination robots in the other negative electrode lamination stage 35 and positive electrode lamination stage 36 are not shown, but basically have the same configuration as the lamination robot 51 in the separator lamination stage 34 described above, and the porous adsorption plate Adsorption type hand using About the porous adsorption | suction plate in the adsorption | suction type hand for these negative electrodes 13 and positive electrodes 12, a static elimination process is arbitrary. In these lamination robots that laminate the negative electrode 13 and the positive electrode 12, charging gradually occurs due to a reciprocating operation in the air, but even if a discharge spark occurs between the pallet 32 and the negative electrode 13 or the positive electrode 12. Therefore, the necessity for the static elimination process is much lower than that of the suction type hand 55 in the laminating robot 51 for laminating separators.

Claims (3)

An electrode stacking stage on which a sheet-like electrode cut into a predetermined shape is placed via a suction-type hand along a conveyance line of a metal pallet, and a sheet-like separator cut into a predetermined shape via a suction-type hand And placing the separator and the separator alternately on the pallet in the electrode stacking stage and the separator stacking stage, and the pallet as the electrode stacking stage and the separator stacking stage. In the method for producing an electrode laminate in a laminated battery in which a laminate is made to circulate a plurality of times through a separator lamination stage and reach a predetermined number,
The adsorption type hand in the separator stacking stage includes a rectangular porous adsorption plate corresponding to the outer shape of the separator,
After a suitable number of stacking treatments, using a rod-shaped ionizer having a length over one side of the porous adsorption plate, the ionizer is moved along the surface of the porous adsorption plate. method for producing charge eliminating step including, electrode stack to the charge removing the entire surface in contact with the separators including the four corners. The four corners of the porous adsorption plate are provided with notches that avoid interference with the electrode laminate clamp of the pallet,
The discharging process neutralizes the range including the notch portion, the manufacturing method of the electrode stack according to claim 1. The method for producing an electrode laminate according to claim 1 or 2 , wherein the static elimination step performs static elimination in a state where the adsorption hand is in a retracted position for receiving a sheet-like separator.

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