JP4166973B2 - PRESS DEVICE FOR PRODUCTION OF BATTERY ELECTRODE AND METHOD FOR PRODUCING BATTERY ELECTRODE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionBattery electrodeMore specifically, with respect to the manufacturing press apparatus, a sheet electrode having an electrode active material layer on at least one surface of a strip electrode current collector is pressed under a high load.Battery electrodeThe present invention relates to a manufacturing press. The present invention also provides:Battery electrodeIt relates to the manufacturing method.
[0002]
[Prior art]
  With recent reductions in size and weight of electronic devices such as various OA devices, VTR cameras, and mobile phones, secondary batteries used as drive power sources for these electronic devices are required to be reduced in size and weight and have higher performance. In order to meet these requirements, development of a lithium ion secondary battery as a non-aqueous electrolyte battery having a high discharge potential and a high discharge capacity has been rapidly promoted and put into practical use.
[0003]
  In general, each electrode of the positive electrode and the negative electrode of a nonaqueous electrolyte battery is prepared by mixing an electrode active material with a binder to prepare an electrode paint (mixture), applying the electrode paint on one side of the electrode current collector, and drying the electrode paint. Subsequently, an electrode paint is applied on the other surface of the electrode current collector and dried to form a sheet-like electrode having an electrode active material layer on both sides of the electrode current collector, and then the sheet-like electrode is added. Manufactured by pressing and cutting to a predetermined size. The electrode active material layer may be formed only on one side of the electrode current collector.
[0004]
  When forming the sheet-like electrode, an electrode active material layer is applied and formed at regular intervals in the length direction of the belt-like electrode current collector surface, while an electrode lead wire is provided between adjacent electrode active material layers. For this welding, it is necessary to secure a portion where the electrode current collector surface is exposed without applying the electrode paint. Usually, the electrode paint is not applied to both ends of the electrode current collector, and a portion where the electrode current collector surface is exposed remains. As described above, the sheet-like electrode has, on each surface thereof, an application section in which the electrode active material layer is applied and formed at regular intervals in the length direction, and a non-application section between adjacent electrode active material layers. The electrode active material layer is not applied and formed on both ends of the ears, and the electrode current collector surface is exposed.
[0005]
  As a conventional apparatus for pressure-processing a sheet electrode, for example, Japanese Patent Laid-Open No. 10-64521 has an electrode active material layer formed on a strip electrode collector at a predetermined pitch in the length direction thereof. And a pair of pressure rolls facing each other with the sheet-like electrode conveyed along a fixed path from both sides, and two pairs of bearing units supporting the roll shaft ends of each roll in pairs, Disclosed is a roller press device comprising a pair of spacers respectively interposed between two pairs of bearing units at the same side end so as to form a thickness adjustment gap between both roll outer peripheral surfaces. Has been.
[0006]
[Problems to be solved by the invention]
  In the above conventional apparatus, since the thickness adjustment gap is formed to prevent the electrode current collector from being stretched or cut, even if an attempt is made to press the sheet-like electrode with a high load, the adjustment gap and the sheet-like electrode are separated from each other. If the sheet-like electrode is pressure-compressed until the thickness becomes equal, no further load can be applied to the sheet-like electrode. For this reason, in the above conventional apparatus, it is not possible to pressurize the sheet-like electrode with a high load, and in order to compress the sheet-like electrode to the target thickness and increase the density of the electrode active material, it is necessary to repeat the pressurizing process several times. was there.
[0007]
  The object of the present invention is to solve the above-mentioned problems of the prior art and to pressurize the sheet electrode with a high load.Battery electrodeThe object is to provide a manufacturing press. In addition, the object of the present invention is toBattery electrodeUsing a manufacturing pressBattery electrodeEspecially non-aqueous electrolyte batteryElectricityIt is to provide a method for manufacturing an electrode.
[0008]
[Means for Solving the Problems]
  The present inventionThe battery electrode manufacturing press apparatus includes the following.
  (1)  A pressure unit having an electrode active material layer formed on at least one surface of a strip electrode current collector and having a pair of pressure rolls facing each other with a sheet-like electrode conveyed along a fixed path from both sides; A cutting unit that cuts off both ends of the electrode current collector on the surface on which the electrode active material layer is formed, upstream of the pressure unit of the sheet-like electrode conveyance path.RudenPress device for pond electrode manufacturingBecause
  The pressure unit includes a backup roll that supports one pressure roll, and a backup roll that supports the other pressure roll,
  In the pressure unit, a pair of bearing units supporting each of both ends of the roll shaft of one pressure roll and a pair of bearing units supporting each of both ends of the roll shaft of the other pressure roll There are shock absorbing spacers between them,
  The impact absorbing spacer is interposed such that the gap between the pressure rolls is 0.01 to 1 mm in a state where no load is applied to the pressure rolls and nothing is sandwiched between the pressure rolls. Have been
  The pressurizing pressure is 3000 kg / cm or more and 20000 kg / cm or less.is there.
  (2) In the pressure unit, a pair of bearing units supporting each of both ends of the roll shaft of one pressure roll, and each of both ends of the roll shaft of the backup roll supporting the one pressure roll Shock absorbing spacers are interposed between the pair of bearing units that are supported,
  And a pair of bearing units supporting both ends of the roll shaft of the other pressure roll and a pair of bearing units supporting both ends of the roll shaft of the backup roll supporting the other pressure roll. Shock absorbing spacers are interposed between the
  The both shock absorbing spacers are interposed such that a gap between both the pressure rolls and the backup roll supporting each of them is 0.01 to 1 mm in a state where no load is applied to the two backup rolls. The press device for producing a battery electrode according to (1) above.
  (3) An electrode having an electrode active material layer formed on at least one surface of the belt-shaped electrode current collector, and having a pair of pressure rolls facing each other with the sheet-like electrode conveyed along a fixed path from both sides. Cutting unit for cutting off both ends of the electrode current collector on the surface on which the electrode active material layer is formed upstream of the pressure unit and the pressure unit of the sheet-like electrode conveyance path A press device for manufacturing a battery electrode comprising:
  The pressure unit includes a backup roll that supports one pressure roll, and a backup roll that supports the other pressure roll,
  In the pressure unit, a pair of bearing units supporting each of both ends of the roll shaft of one pressure roll and each of both ends of the roll shaft of the backup roll supporting the one pressure roll are supported. Shock absorbing spacers are interposed between a pair of bearing units,
  And a pair of bearing units supporting both ends of the roll shaft of the other pressure roll and a pair of bearing units supporting both ends of the roll shaft of the backup roll supporting the other pressure roll. Shock absorbing spacers are interposed between the
  The both shock absorbing spacers are interposed such that both the pressure rolls and the backup roll supporting each of the backup rolls have a gap of 0.01 to 1 mm with no load applied to the two backup rolls. ,
  The press apparatus for manufacturing a battery electrode, wherein the pressurizing pressure is 3000 kg / cm or more and 20000 kg / cm or less.
[0009]
  According to the inventionBattery electrodeIn the manufacturing press apparatus, since the cutting unit is provided upstream of the pressurizing unit in the sheet-like electrode conveyance path, the both-side ear ends are cut in advance before the sheet-like electrode is pressurized. When the conveyed sheet-like electrode is pressurized with a high load, the electrode current collector extends mainly in the sheet-like electrode conveyance direction. At this time, when the sheet-like electrode is pressed without cutting the both-side ear ends, the regions where the electrode active material layer is formed on the current collector surface and the both-side ear ends where the electrode active material layer is not formed There is a difference in the degree of stretching. That is, the degree of stretching at the both ends is smaller than the degree of stretching in the region where the electrode active material layer is formed. For this reason, the flatness of the sheet-like electrode after pressure processing may be impaired, which may cause wrinkles and breakage. Of the present inventionBattery electrodeIn the manufacturing press apparatus, as described above, the both ends of the ears are cut in advance before the sheet-like electrode is pressed, so that the sheet-like electrode is pressurized with a high load without causing wrinkles or breakage. Can do.
[0013]
  The present invention also provides an electrode mixture paint containing an electrode active material and a binder on at least one surface of a strip-shaped electrode current collector., With a certain gap in the length direction of the electrode current collectorApply and apply an electrode active material layer to the at least one side of the electrode current collectorAnd the non-application section where the electrode current collector surface is exposed are alternately arranged in the length direction of the electrode current collector,And the electrode collector paint is not applied to both ends of the electrode current collector to form a sheet-like electrode in which the electrode current collector surface is exposed,
  Excising the both ears so as not to leave the exposed electrode current collector surface,
  After that, the sheet electrode3000 kg / cm or more and 20000 kg / cm or lessIt is a manufacturing method of the electrode for batteries including pressurizing with the pressure of.
[0015]
  In the present invention,3000 kg / cm or more and 20000 kg / cm or lessPressurize with high pressureTheBy pressing the sheet-like electrode with such a high load, the electrode active material layer can be compressed to the target thickness with a small number of pressurization times, and the density of the active material per electrode volume can be increased.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present inventionBattery electrodeAn embodiment of a manufacturing press apparatus will be described with reference to the drawings.
[0017]
  FIG. 1 illustrates the present invention.Battery electrodeIt is a perspective view which shows an example of embodiment of the press apparatus for manufacture. In FIG. 1, a sheet-like electrode having an electrode active material layer (C) formed on at least one surface of a strip-shaped electrode current collector (B) is conveyed in the direction of arrow (A). In the following description, the left and right sides are referred to as the left and right when viewed from the upstream side to the downstream side of the sheet-like electrode conveyance path.
  The press apparatus shown in FIG. 1 includes a feeding unit (1), a cutting unit (2), a pressure unit (3), and a winding unit (not shown) in this order from the upstream side of the sheet-like electrode transport path. .
[0018]
  In order to facilitate the following description, the sheet-like electrode fed out from the feeding unit (1) will be described with reference to FIG. FIG. 2 shows the present invention.Battery electrodeIt is a top view which shows an example of the sheet-like electrode for manufacturing this.
[0019]
  The sheet-like electrode (M) is obtained by forming a number of rectangular electrode active material layers (C) having a width (Wc) on a strip-shaped electrode current collector (B) having a width (Wb). The active material layers (C) are arranged in a line with a gap between adjacent ones at a constant pitch (P) in the length direction of the electrode current collector. Thus, in the length direction, the application section (S) in which the electrode active material layer (C) is formed on the strip electrode collector (B) and the non-application section in which the surface of the electrode current collector (B) is exposed. (N) are formed alternately. Even in the coating section (S), the electrode active material layer (C) is not formed on the right and left ear ends (El) (Er) of the electrode current collector (B), and the electrode current collector (B ) The exposed part remains.
  AimBattery electrodeDepending on the type, the formation pattern of the application section (S) and the non-application section (N) may be the same or different on both sides of the current collector (B). In some cases, the active material layer (C) is formed only on one side of the current collector (B).
[0020]
  Referring to FIG. 1, a cutting unit (2) is provided downstream of the feeding unit (1) in the sheet-like electrode transport path. In FIG. 1, the cutting unit (2) is shown conceptually. As the cutting unit (2), for example, a known cutting means such as a rotary blade such as a shear method or a gang method or a laser can be used.
[0021]
  The cutting unit (2) cuts off the left and right ear ends (El) (Er) of the electrode current collector (B) described in FIG.
  If dust or the like is generated when cutting the ear ends (El) (Er) on both sides, use a rotating brush, ultrasonic wave, air knife, dust suction device, etc. Is preferably removed.
[0022]
  With reference to FIG. 3, the sheet-like electrode after cutting off both ear ends (El) (Er) with the above-described cutting unit (2) will be described. FIG. 3 is a plan view showing an example of a sheet-like electrode from which the both-side ear ends of the current collector are removed.
  In FIG. 3, the width (W1) of the current collector (B) after the resection of both ear ends is equal to the width of the electrode active material layer (C) in this figure. In the present invention, both ear ends (El) (Er) are excised so as not to leave portions where the electrode current collector (B) surface is exposed on the left and right sides of the electrode active material layer (C). That is, the width (W1) is cut so that the relationship between (Wb) and (Wc) described in FIG. 2 is (W1) ≦ (Wc) <(Wb). As described in FIG. 2, in the length direction, the coating section (S) where the electrode active material layer (C) is formed and the non-coating section (N) where the surface of the electrode current collector (B) is exposed. Are lined up alternately.
[0023]
  Referring to FIG. 1, a pressure unit (3) is provided downstream of the cutting unit (2) in the sheet-like electrode conveyance path. In the example of FIG. 1, a four-high rolling mill is provided as the pressure unit (3).
  In FIG. 1, a pressurizing unit (3) includes a horizontal upper roll (11) and a lower roll (left and right) extending in the left-right direction and arranged to face each other with a sheet-like electrode conveyed along a fixed path. 12). These upper and lower rolls (11) and (12) have a length wider than the width (W1) described in FIG.
[0024]
  The upper roll (11) is provided with an upper rotation shaft (13) so that the left and right ends thereof protrude left and right from the end surface of the upper roll (11). Similarly, the lower rotating shaft (14) is also provided on the lower roll (12) so that its left and right ends protrude left and right from the end surface of the lower roll (12). The left and right ends of the upper rotating shaft (13) are supported by a pair of left and right upper bearing units (15). The left and right ends of the lower rotating shaft (14) are supported by a pair of left and right lower bearing units (16).
[0025]
  As a pressure roll, a known mechanism for controlling the thickness distribution in the left-right direction of the sheet-like electrode, for example, roll bending, roll reverse bending, crown roll, crown variable roll, roll cloth, etc. may be used in combination. is there.
  As the material of both rolls (11) and (12), a metal such as steel or a hard synthetic resin is generally used. Both rolls (11) and (12) may be a combination of the same materials or different materials. In use, the surface temperatures of both rolls (11) and (12) are generally kept constant in the range from room temperature to 200 ° C.
[0026]
  In the example of FIG. 1, a pair of left and right shock absorbing spacers (17) are interposed between left and right upper and lower bearing units (15) and (16) on the same left and right sides.
  The shock absorbing spacer (17) can be used for both pressurization when no pressure is applied to the pressure rolls (11) and (12) and nothing is sandwiched between the pressure rolls (11) and (12). It is good to interpose so that the clearance gap between rolls (11) and (12) may be set to 0.01-1 mm. When a load of 500 to 20000 kg / cm is applied to the pressure roll in this state, both pressure rolls (11) and (12) come into contact with each other without any gap. The sheet-like electrode can be pressurized with a high load, and vibrations of both rolls (11) and (12) are reduced. Therefore, even when the sheet-like electrode (M1) having the application section (S) and the non-application section (N) described in FIG. 3 is pressurized, the application section (S) is added to the non-application section (N). Since the vibrations of both rolls (11) and (12) due to the impact when the pressure roll is transferred are mitigated, the electrode current collector (B) in the non-coating zone (N) is not wrinkled.
[0027]
  Examples of the material for the shock absorbing spacer (17) include metals such as iron, copper, aluminum and lead, resins such as polyethylene terephthalate, polyester, vinyl chloride, polyethylene, polyimide, Teflon, cellophane, nylon and polypropylene, and glass. A fiber, a carbon fiber, a nonwoven fabric, etc., the composite of these materials, etc. are used.
[0028]
  In the example of FIG. 1, the upper roll (11) is supported by the upper backup roll (21), and the lower roll (12) is supported by the lower backup roll (22). The upper backup roll (21) is provided with an upper rotation shaft (23) so that the left and right ends thereof protrude left and right from the end surface of the upper backup roll (21). Similarly, the lower backup roll (22) is also provided with a lower rotating shaft (24) so that its left and right ends protrude left and right from the end face of the lower backup roll (22). The left and right ends of the upper rotating shaft (23) are supported by a pair of left and right upper bearing units (25). The left and right ends of the lower rotating shaft (24) are supported by a pair of left and right lower bearing units (26).
[0029]
  The backup rolls (21) and (22) are usually larger in diameter than the pressure rolls (11) and (12). As the backup rolls (21) and (22), a plurality of rolls whose left and right lengths are shorter than the pressure rolls (11) and (12) may be used. In the example of FIG. 1, the backup rolls (21) and (22) are each composed of five rolls. Each load of multiple backup rolls can be controlled, so by adjusting the load balance in the left-right directionBattery electrodeThe thickness distribution in the left-right direction can be controlled.
  As the material of the backup rolls (21) and (22), a metal such as steel or a hard synthetic resin is used as in the material of the pressure rolls (11) and (12). The backup rolls (21) and (22) may be made of the same material or different materials from the pressure rolls (11) and (12) supported by the backup rolls (21) and (22).
[0030]
  In the example of FIG. 1, a pair of left and right upper shock absorbing spacers (27) are interposed between the left and right upper bearing units (15) and (25) on the same left and right sides. A pair of left and right lower impact absorbing spacers (28) are interposed between the left and right lower bearing units (16) and (26) on the same left and right sides.
[0031]
  The upper and lower impact absorbing spacers (27), (28) are the pressure rolls (11), (12) and the backup rolls (21), (22) It is good to interpose so that both may be set to 0.01-1 mm. When a load of 500 to 20000 kg / cm is applied in this state, the pressure rolls (11) and (12) and the backup rolls (21) and (22) supporting the respective rolls contact each other. The sheet-like electrode can be pressurized with a high load, and vibrations of both pressure rolls (11) and (12) are reduced. Therefore, even when the sheet-like electrode (M1) having the application section (S) and the non-application section (N) described in FIG. 3 is pressurized, the application section (S) is added to the non-application section (N). Since the vibrations of both rolls (11) and (12) due to the impact when the pressure roll is transferred are mitigated, the electrode current collector (B) in the non-coating zone (N) is not wrinkled.
[0032]
  Examples of the material of the upper and lower shock absorbing spacers (27) and (28) include the same materials as those of the shock absorbing spacer (17). For example, metals such as iron, copper, aluminum, lead, polyethylene terephthalate, polyester, vinyl chloride, polyethylene, polyimide, Teflon, cellophane, nylon, polypropylene, etc., glass fiber, carbon fiber, non-woven fabric, etc. And the like.
[0033]
  As described above, in the example of FIG. 1, a four-high rolling mill is provided as the pressure unit (3). A two-high rolling mill not having the backup rolls (21) and (22) or a multi-high rolling mill having a multi-stage backup roll can also be used.
  Further, in the example of FIG. 1, an impact absorbing spacer (17) is interposed, and upper and lower impact absorbing spacers (27) and (28) are respectively interposed. As shown in FIG. 1, the spacer (17) may be used in combination with the upper and lower spacers (27) and (28), or any one of the spacer (17) and the upper and lower spacers (27) and (28) may be used. . The shock absorbing spacer (17) and the vertical shock absorbing spacers (27), (28) may not be used.
[0034]
  When pressurizing the sheet electrode, dust or the like may be generated. In this case, care should be taken not to attach dust to the pressure rolls (11), (12) and backup rolls (21), (22), and if dust adheres, for example, felt pads, resin Dust may be removed with a knife, a metal blade, ultrasonic waves, a dust suction device or the like.
[0035]
  With reference to FIG. 4, the effect obtained by excising the left and right ear ends (El) (Er) in advance before pressurization will be described. FIG. 4 is a perspective view of an application section of the sheet-like electrode shown in FIG. In the example of FIG. 4, the coating section (S) is formed with the same formation pattern on both sides of the current collector (B).
[0036]
  When the conveyed sheet-like electrode is pressurized with a high load, the electrode current collector (B) extends mainly in the conveying direction (A). When the sheet electrode is pressed with a high load without excising the left and right ear ends (El) (Er), the electrode active material layer (C) is formed on the surface of the current collector (B). Compared with the degree of stretching (Xc), the degree of stretching (Xb) at the both-side ear ends (El) (Er) where the electrode active material layer (C) is not formed is small. Due to the difference between the degree of stretching (Xc) and (Xb), the flatness of the sheet electrode after pressurization is impaired, which may cause wrinkles and breakage. As described with reference to FIG. 1, the pressing device of the present invention has a cutting unit (2) for cutting off both ear ends (El) (Er) upstream of the pressurizing unit (3) in the sheet-like electrode transport path. Since it is provided, both ears (El) (Er) that cause the difference in the degree of stretching are cut in advance and then pressurized. For this reason, even if it pressurizes a sheet-like electrode with a heavy load, the flatness of a sheet-like electrode is not impaired and a wrinkle and a fracture | rupture do not arise.
[0037]
  With reference to FIG. 1, the sheet-like electrode is fed out from the feeding unit (1) and conveyed in the direction indicated by the arrow (A). The electrode current collector layer (C) is not formed, and the electrode current collector (B) surface is exposed on both sides of the electrode current collector (El) (Er). It is excised by the cutting unit (2) provided upstream from 3). After the ear ends (El) and (Er) on both sides are excised, the sheet electrode passes between the upper and lower pressure rolls (11) and (12). When the coating section in which the active material layer (C) is coated and formed on the electrode current collector (B) passes between the upper and lower pressure rolls (11) and (12), the active material layer (C) Pressurized and compressed. As described with reference to FIG. 4, since both ear ends (El) (Er) are cut in advance before pressurization, the flatness of the sheet-like electrode is impaired even if the sheet-like electrode is pressurized with a high load. No wrinkles or breakage. Referring to FIG. 3, even when a sheet-like electrode in which the coating section (S) and the non-coating section (N) are alternately arranged in the length direction of the electrode current collector is pressed, the shock absorbing spacer (17 ) And / or upper and lower impact absorbing spacers (27), (28), both rolls (11), (12) due to impact when the pressure roll moves from the coating section (S) to the non-coating section (N). ) Is mitigated, so that no wrinkles are generated in the electrode current collector (B) in the non-coating zone (N). After pressurization, the sheet-like electrode is taken up by a take-up unit (not shown).
[0038]
  The present inventionBattery electrodeIt also relates to the manufacturing method.
  In the present invention, first, an electrode active material and a binder are mixed together with a solvent to prepare a slurry electrode mixture paint. At this time, a conductive agent or an additive may be added as necessary.
[0039]
  The electrode active material is not particularly limited as long as it is conventionally used as an electrode active material, and various materials can be used.
  As the positive electrode active material, for example, an oxide or a carbon material that can be doped / undoped with lithium ions can be used. Examples of such oxides include composite oxides containing lithium. For example, lithium cobaltate Li_xCoO₂(0 <x ≦ 1.0), lithium manganate Li_{1 + x}Mn_2-xO_Four(0 ≦ x ≦ 1/3), lithium nickelate Li_xNiO₂(0 <x ≦ 1.0). The average particle diameter of these oxide powders is preferably about 1 to 40 μm.
[0040]
  As the negative electrode active material, for example, an oxide such as a carbonaceous material, a lithium metal, a lithium alloy, or a tin oxide is used. The carbonaceous material is not particularly limited, and for example, amorphous carbon, acetylene black, petroleum coke, coal coke, artificial graphite, natural graphite, graphite-based carbon fiber, non-graphitizable carbon, etc. can be used. . Those skilled in the art can appropriately select from these according to the characteristics of the target battery.
[0041]
  The binder for the electrode paint is not particularly limited, and various binders such as a crystalline resin and an amorphous resin that have been conventionally used can be used. For example, as the binder, polyacrylonitrile (PAN), polyethylene terephthalate, polyvinylidene fluoride (PVDF), polyvinyl fluoride, fluorocarbon resins such as fluororubber, and the like can be used.
  The binder is usually used in an amount of 1 to 40 parts by weight, preferably 2 to 25 parts by weight, particularly preferably 5 to 15 parts by weight, based on 100 parts by weight of the electrode active material.
[0042]
  The solvent for the electrode paint is not particularly limited, and various solvents conventionally used in preparing the electrode paint can be used. For example, N-methylpyrrolidone (NMP), methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), cyclohexanone, toluene and the like can be mentioned.
[0043]
  A conductive agent can be added for the purpose of supplementing the electron conductivity of the electrode active material, if necessary. The conductive agent is not particularly limited, and various known conductive agents may be used. Examples thereof include acetylene black, graphite, and gold / silver / copper fine particles. Furthermore, various known additives such as lithium carbonate, oxalic acid and maleic acid can also be added.
[0044]
  Mixing of an electrode active material, a binder, a conductive agent, a solvent, and the like can be performed by a conventional method. For example, they are mixed in a dry air or inert gas atmosphere by a roll mill method.
[0045]
  Next, the obtained slurry-like electrode paint is applied on the belt-like electrode current collector. The application may be performed on both sides of the current collector or only on one side depending on the purpose of the electrode. In addition, when applying the electrode paint on both sides of the current collector, it may be applied to both sides at the same time and the next drying step may be performed, or it may be applied to one side and the drying step followed by application to the other side. And you may perform a drying process.
[0046]
  When applying the electrode paint, in order to form the application section (S) and the non-application section (N) at a predetermined pitch (P) in the length direction of the current collector, for example, the application liquid is intermittently supplied to the die nozzle. A method (Japanese Patent Application Laid-Open No. 2000-149929), a method of previously masking the non-application section (N) (Japanese Patent Application No. 2001-119140 filed on April 18, 2001) by the applicant, etc. may be applied. . Of course, other various methods may be applied.
[0047]
  Application of the electrode paint to the electrode current collector is a known method such as extrusion coating, gravure coating, reverse roll coating, dip coating, kiss coating, doctor coating, knife coating, curtain coating, nozzle coating, screen printing, etc. It can be performed by a coating method.
[0048]
  In the present invention, as the electrode current collector, a metal foil, a metal sheet, a punching metal, a metal net or the like is used, and a metal foil or a punching metal is preferable. The metal material for the electrode current collector is not particularly limited, and various metal materials conventionally used for electrode current collectors can be used. Examples of such a metal material include copper, aluminum, stainless steel, nickel, iron and the like, and copper, aluminum and the like are preferable. The thickness of the electrode current collector is usually 1 to 30 μm, preferably 5 to 20 μm.
[0049]
  Following application of the electrode paint, drying is performed to remove the solvent. Drying can be performed by a conventional method. For example, drying is performed at 30 to 150 ° C. for about 5 to 15 minutes. Thus, referring to FIG. 2, the electrode active material layer (C) is formed on one side or both sides of the electrode current collector (B), and the coating section (S) and the non-coating section (N) are formed into the electrode collector. A sheet-like electrode (M) formed at a predetermined pitch (P) in the length direction of the electric body is obtained. In the sheet-like electrode (M), the electrode active material layer (C) is not formed by coating on both ears (El) (Er) of the electrode current collector (B), and the surface of the electrode current collector (B) Exposed.
[0050]
  After drying, the both ends of the ears (El) (Er) are excised so as not to leave the exposed current collector (B) surface, and then the sheet-like electrode is pressed to form the electrode active material layer. The thickness is made thin and uniform, and the density of the active material per electrode volume is increased. At this time, the press device of the present invention including a cutting unit and a pressure unit may be used.
[0051]
  Pressurized pressureIs over 3000kg / cmIt is. Pressurization with a high load of 1000 kg / cm or moreSoA multi-high rolling mill such as a four-high rolling mill is used to uniformly press the sheet electrode while suppressing the bending of the pressure roll.TheUpper pressure limitIs 2It is about 0000 kg / cm, and preferably about 10000 kg / cm.
[0052]
  The surface treatment of the sheet-like electrode may be performed immediately before and / or immediately after the pressing process. The surface treatment can be performed using, for example, a heating furnace using far-infrared rays, hot air, or the like, or a radiation irradiation apparatus such as an electron beam, α ray, β ray, γ ray, X ray, or ultraviolet ray.
[0053]
  After the pressing process, the sheet-like electrode is cut into a predetermined dimension. The cutting generally includes a slitting process for making the electrode a predetermined width along the manufacturing flow direction and a cutting process for making the electrode a desired length.
[0054]
【Example】
  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[Example 1: Production of positive electrode]
  A slurry-like positive electrode paint having the following composition was prepared.
[0055]
(Composition of positive electrode paint)
Positive electrode active material: 100 parts by weight of lithium cobalt oxide
Conductive agent: 6 parts by weight of acetylene black
Binder: Fluororubber 5 parts by weight
Solvent: 39 parts by weight of N-methylpyrrolidone (NMP)
Solvent: 39 parts by weight of methyl isobutyl ketone (MIBK)
[0056]
  First, 5 parts by weight of a binder was dissolved in 20 parts by weight of MIBK to prepare a lacquer. Next, 25 parts by weight of the lacquer was added to 6 parts by weight of the conductive agent and kneaded, and then 19 parts by weight of MIBK and both parts of NMP 39 were added to the kneaded material and dissolved to prepare a paste. 100 parts by weight of the positive electrode active material was added to 89 parts by weight of the paste and mixed well to obtain a positive electrode paint.
[0057]
  Next, referring to FIG. 2, the above positive electrode paint is intermittently applied by nozzle coating to one side of an electrode current collector (B) made of an aluminum foil having a thickness of 20 μm and a width (Wb) of 400 mm. The electrode active material layer (C) was formed by drying in a drying furnace at ˜130 ° C. The length of the current collector in the coating section (S) was 400 mm, the width (Wc) was 380 mm, and the length of the current collector in the non-application section (N) was 20 mm. Thereafter, a similar coating operation was performed on the other surface of the aluminum foil to form an electrode active material layer (C). As a result, a sheet-like electrode (M) having an overall thickness of the electrode current collector (B) and the electrode active material layers (C) on both sides of 350 μm was obtained.
[0058]
  Using the press device of the present invention comprising a cutting unit (2) and a pressure unit (3), the obtained sheet-like electrode (M) has both ear ends (El) (Er ), And then the sheet electrode was pressurized. Referring to FIG. 3, the width (W1) after excision of both ear ends and before pressurization was 370 mm. Referring to FIG. 1, metal pressure rolls (11) and (12) having a diameter of 420 mm and five metal backup rolls (21 and 22) having a diameter of 500 mm were used. Bearing unit (15) so that the gap between the unloaded rolls (11) and (12) is 0.46 mm with nothing sandwiched between the upper and lower pressure rolls (11) and (12) Metal shock absorbing spacers (17) and (17) were interposed between (15) and the bearing units (16) and (16). Vertical shock absorbing spacers (27), (27), (28) and (28) were not interposed. A load was applied so that the sheet-like electrode having a thickness of 350 μm before pressurization could be compressed to a target thickness of 230 μm to produce a battery electrode. The load applied to the pressure part at this time is 4600 kg / cm. When no sheet electrode is sandwiched between the upper and lower rolls (11) and (12), both rolls (11) and (12) It was in contact with no gap.
[0059]
[Comparative Example 1]
  A battery electrode was produced in the same manner as in Example 1 except that both ear ends (El) (Er) were not excised. During the pressurization, the load applied to the pressurizing part was 4600 kg / cm.
[0060]
[Example 2](Reference example)
  A battery electrode was produced in the same manner as in Example 1 except that the shock absorbing spacers (17) and (17) were not interposed. During the pressurization, the load applied to the pressurizing part was 1800 kg / cm.
[0061]
[Example 3]
  The gap between the pressure roll (11) and the backup roll (21) and the pressure roll (12) and the backup roll (22) without any impact absorbing spacers (17) and (17) and without any load. Except for interposing metal upper shock absorbing spacers (27) and (27) and metal lower shock absorbing spacers (28) and (28) so that the gap between them is 0.1 mm. A battery electrode was produced in the same manner as in Example 1. During the pressurization, the load applied to the pressurizing part was 3000 kg / cm.
[0062]
[Example 4]
  A battery electrode was produced in the same manner as in Example 1 except that the upper impact absorbing spacers (27) and (27) and the lower impact absorbing spacers (28) and (28) were interposed. The shock absorbing spacers (27) and (28) were made of the same material and the same dimensions as the shock absorbing spacers (27) and (28) used in Example 3. During the pressurization, the load applied to the pressurizing part was 7400 kg / cm.
[0063]
  The states of the battery electrodes produced in Examples 1 to 4 and Comparative Example 1 were observed. In Examples 1, 3, and 4, the obtained battery electrode had good flatness, and the electrode current collector (B) exposed in the non-application section (N) was not wrinkled or broken. In Example 2, the electrode current collector (B) exposed in the non-application section (N) was wrinkled, but there was no problem in practical use. On the other hand, in Comparative Example 1, the flatness of the battery electrode was poor, and it was broken at several places.
[0064]
【The invention's effect】
  According to the present invention, the sheet-like electrode can be pressurized with a high load, and the flatness of the sheet-like electrode is not impaired even after being pressurized with a high load, and wrinkles and breakage do not occur. The electrode active material layer can be compressed to the target thickness with a small number of pressurization times, and the density of the active material per electrode volume can be increased.
[Brief description of the drawings]
FIG. 1 of the present inventionBattery electrodeIt is a perspective view which shows an example of embodiment of the press apparatus for manufacture.
FIG. 2 in the present inventionBattery electrodeIt is a top view which shows an example of the sheet-like electrode for manufacturing this.
FIG. 3 is a plan view showing a sheet-like electrode in which both ends of the current collector are cut off.
4 is a perspective view of an application section of the sheet-like electrode shown in FIG. 2. FIG.
[Explanation of symbols]
(1): Feeding unit
(2): Cutting unit
(3): Pressure unit
(11): Pressure roll
(12): Pressure roll
(17): Shock absorbing spacer
(21): Backup roll
(22): Backup roll
(27): Shock absorbing spacer
(28): Shock absorbing spacer
(B): Electrode current collector
(C): Electrode active material layer
(M): Sheet electrode
(M1): Sheet electrode
(El) (Er): Both ear ends

Claims (4)

A pressure unit having an electrode active material layer formed on at least one surface of a strip electrode current collector and having a pair of pressure rolls facing each other with a sheet-like electrode conveyed along a fixed path from both sides; A cutting unit that cuts off both ends of the electrode current collector on the surface on which the electrode active material layer is formed, upstream of the pressure unit of the sheet-like electrode conveyance path. a that batteries electrode manufacturing a press device,
The pressure unit includes a backup roll that supports one pressure roll, and a backup roll that supports the other pressure roll,
In the pressure unit, a pair of bearing units supporting each of both ends of the roll shaft of one pressure roll and a pair of bearing units supporting each of both ends of the roll shaft of the other pressure roll There are shock absorbing spacers between them,
The impact absorbing spacer is interposed such that the gap between the pressure rolls is 0.01 to 1 mm in a state where no load is applied to the pressure rolls and nothing is sandwiched between the pressure rolls. Have been
The press apparatus for manufacturing a battery electrode, wherein the pressurizing pressure is 3000 kg / cm or more and 20000 kg / cm or less. In the pressure unit, a pair of bearing units supporting each of both ends of the roll shaft of one pressure roll and each of both ends of the roll shaft of the backup roll supporting the one pressure roll are supported. Shock absorbing spacers are interposed between the pair of bearing units,
And a pair of bearing units supporting both ends of the roll shaft of the other pressure roll and a pair of bearing units supporting both ends of the roll shaft of the backup roll supporting the other pressure roll. between the shock absorbing spacer has been interposed respectively,
The both shock absorbing spacers are interposed such that a gap between both the pressure rolls and the backup roll supporting each of them is 0.01 to 1 mm in a state where no load is applied to the two backup rolls. The press apparatus for manufacturing a battery electrode according to claim 1 . A pressure unit having an electrode active material layer formed on at least one surface of a strip electrode current collector and having a pair of pressure rolls facing each other with a sheet-like electrode conveyed along a fixed path from both sides; A cutting unit for excising both ends of the electrode current collector on the surface on which the electrode active material layer is formed, upstream of the pressure unit of the sheet-like electrode conveyance path. A press device for manufacturing a battery electrode,
The pressure unit includes a backup roll that supports one pressure roll, and a backup roll that supports the other pressure roll,
In the pressure unit, a pair of bearing units supporting each of both ends of the roll shaft of one pressure roll and each of both ends of the roll shaft of the backup roll supporting the one pressure roll are supported. Shock absorbing spacers are interposed between the pair of bearing units,
And a pair of bearing units supporting both ends of the roll shaft of the other pressure roll and a pair of bearing units supporting both ends of the roll shaft of the backup roll supporting the other pressure roll. Shock absorbing spacers are interposed between the
The both shock absorbing spacers are interposed such that both the pressure rolls and the backup roll supporting each of the backup rolls have a gap of 0.01 to 1 mm with no load applied to the two backup rolls. ,
The press apparatus for manufacturing a battery electrode, wherein the pressing pressure is 3000 kg / cm or more and 20000 kg / cm or less. An electrode mixture paint containing an electrode active material and a binder is applied to at least one surface of a strip-shaped electrode current collector with a certain gap in the length direction of the electrode current collector, and the electrode active material is applied to the at least one surface of the electrode current collector. The coating section in which the material layer is formed and the non-coating section in which the electrode current collector surface is exposed are alternately arranged in the length direction of the electrode current collector, and the electrode mixture paint is applied to both ends of the electrode current collector. Form a sheet-like electrode that is not coated and the electrode current collector surface is exposed,
Excising the both ears so as not to leave the exposed electrode current collector surface,
Then, the manufacturing method of the electrode for batteries including pressurizing a sheet-like electrode with the pressure of 3000 kg / cm or more and 20000 kg / cm or less .

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