JP5954220B2 - Electrode manufacturing apparatus and electrode manufacturing method - Google Patents

Description

  The present invention relates to an electrode manufacturing apparatus and an electrode manufacturing method.

  Conventionally, lithium ion secondary batteries, nickel-hydrogen secondary batteries, and the like are well known as power storage devices mounted on vehicles such as EVs (Electric Vehicles) and PHVs (Plug-in Hybrid Vehicles). Some of these power storage devices have an electrode assembly formed by winding, for example, an electrode having an active material layer on the surface of a strip-shaped metal foil or by laminating an electrode sheet obtained by punching the electrode There is.

  By the way, in the case of a strip-shaped electrode, warping in the longitudinal direction may occur due to being wound and stored in a roll shape or heated (baked) while being wound in a roll shape. When winding or punching and stacking electrodes that have warped, there is a risk that the edge of the electrode assembly will be displaced and the performance as a power storage device may be reduced. It is preferable to correct the warp.

  Although not such an apparatus for correcting the warping of the electrode, a warp correcting apparatus for correcting the warping of the metal strip has been proposed (for example, Patent Document 1). In the warp correction device of Patent Document 1, by providing a bridle roll on each of the upstream side and downstream side of the continuous heat treatment furnace in the transport direction of the metal strip, and performing heat treatment while applying tension to the metal strip by each bridle roll, While correcting the warp, it reduces the internal stress that accompanies the correction.

JP 2000-109933 A

  However, in the warp correction device of Patent Document 1, since the bridle roll is further passed after the continuous heat treatment furnace, there is a possibility that the warp is generated again in the metal strip whose warp has been corrected.

  This invention was made paying attention to the problem which exists in the said prior art, The objective is providing the manufacturing apparatus of an electrode which can correct the curvature of an electrode, and can reduce internal stress, and the manufacturing method of an electrode There is to do.

An electrode manufacturing apparatus that solves the above problems is an electrode manufacturing apparatus having an active material layer containing an active material on at least one surface of a strip-shaped metal foil, and the electrode is placed in the longitudinal direction of the electrode at room temperature. A correction unit having a correction roll that corrects by warping in a direction opposite to the warp, a heating unit that is provided on the downstream side of the correction unit in the transport direction of the electrode and heats the electrode in a flat state, and the transport direction SUMMARY said provided immediately downstream of the heating unit, forming the electrode, or possess a processed portion for winding, the shape of the electrode is not deformed between the processing unit and the heating unit in the And

  According to this, the curvature of the electrode is corrected by the correction roll of the correction unit, and the internal stress is reduced by heating the electrode in a flat state in the heating unit. And, since the processing portion is provided immediately downstream of the heating portion, the electrode is molded in a state where the warpage of the electrode is corrected and the residual stress is reduced without deforming the electrode in advance, or Can be wound. Therefore, it is possible to correct the warping of the electrode and reduce internal stress.

  Moreover, about the manufacturing apparatus of the said electrode, it is preferable that the said heating part has a support roll which supports the electrode conveyed by this heating part. According to this, it can suppress that an active material layer is damaged compared with the floating type which floats and conveys an electrode, for example by spraying a fluid.

  Moreover, about the said manufacturing apparatus of the electrode, it is preferable that the said heating part is a heating furnace which has the heating space which the said electrode passes and heats this passed electrode. According to this, the whole electrode can be heated uniformly by allowing the electrode to pass through the heating space, and internal stress can be prevented from remaining in a part of the electrode.

  In the electrode manufacturing apparatus, the active material layer includes a binder that binds the active material, and the temperature of the heating unit is 120 ° C. or higher and less than the thermal decomposition temperature of the binder. Preferably there is. According to this, it can suppress that a binder thermally decomposes, reducing residual stress by heat processing.

An electrode manufacturing method that solves the above problem is a method for manufacturing an electrode having an active material layer containing an active material on at least one surface of a strip-shaped metal foil, wherein the electrode is placed in the longitudinal direction of the electrode at room temperature. A correction process for correcting by warping in the opposite direction to the warp, a heating process for heating the electrode that has corrected the warp in a flat state, and a processing process for forming or winding the heated electrode without being deformed in advance, have a, and summarized in that there is no step of deforming the shape of the electrode between said heating step and said processing step.

  According to this, while correcting the curvature of an electrode by a correction process, an internal stress can be reduced by heating an electrode in a flat state by a heating process. In the processing step, the heated electrode is formed or wound without being deformed in advance. Therefore, it is possible to correct the warping of the electrode and reduce internal stress.

  According to the present invention, it is possible to correct the warping of the electrode and reduce the internal stress.

The front view which shows the manufacturing apparatus of an electrode typically. (A) And (b) is a front view which shows typically a part of manufacturing apparatus of the electrode in another embodiment. The front view which shows typically a part of manufacturing apparatus of the electrode in another embodiment.

Hereinafter, an embodiment of an electrode manufacturing apparatus will be described.
As shown in FIG. 1, the manufacturing apparatus 10 of the present embodiment includes a supply mechanism 12 as a supply unit that supplies a strip-shaped electrode 11 used in a lithium ion secondary battery as a power storage device. The supply mechanism 12 includes, for example, a supply roll 12a that sets an electrode roll 11a wound around a core material in a roll shape and supplies the electrode 11 to the apparatus.

  Here, the electrode 11 has an active material layer 11c containing an active material, a conductive agent, and a binder on both surfaces of a strip-shaped metal foil 11b. In the electrode 11 for the positive electrode, the metal foil 11b is, for example, an aluminum foil, and an active material for the positive electrode is used as the active material. Moreover, in the electrode 11 for negative electrodes, the metal foil 11b is copper foil, for example, and the active material for negative electrodes is used as an active material. The binder used for the active material layer 11c is, for example, polyvinylidene fluoride having a thermal decomposition temperature of 375 ° C., polytetrafluoroethylene having a thermal decomposition temperature of 390 ° C., or the like.

  In addition, the electrode 11 is stored in a state of the electrode roll 11a for a predetermined period or is subjected to a heating (baking) process so that the electrode 11 is bent along the circumferential direction of the electrode roll 11a. Are warped in the longitudinal direction.

  In the manufacturing apparatus 10, the electrode 11 is drawn from the upper part of the supply roll 12 a (electrode roll 11 a) toward the side in the transport direction Y <b> 1 of the electrode 11 and supplied. For this reason, in the manufacturing apparatus 10, the electrode 11 is curved downward due to the brazed warp.

  On the downstream side of the supply mechanism 12 in the transport direction Y1 of the electrode 11, a correction mechanism 14 is provided as a correction unit that corrects the warpage of the electrode 11 in the longitudinal direction. The correction mechanism 14 has a cylindrical first guide roll 15a that is supported so as to be rotatable about an axis and guides the electrode 11 in a warping direction of the electrode 11 (downward in the present embodiment). The transport direction Y1 of the electrode 11 is directed downward in the present embodiment by the first guide roll 15a.

  The correction mechanism 14 is supported below the first guide roll 15a so as to be rotatable around the axis, and the conveyance direction Y1 of the electrode 11 guided by the first guide roll 15a is opposite (in the present embodiment, upward). It has a cylindrical second guide roll 15b that is reversed in the direction of heading. The second guide roll 15b conveys the electrode 11 so as to follow the outer peripheral surface of the second guide roll 15b, thereby bending the electrode 11 in a direction opposite to the warp of the electrode 11.

  Further, the correction mechanism 14 is supported above the second guide roll 15b so as to be rotatable about the axis, and changes the transport direction Y1 of the electrode 11 guided by the second guide roll 15b. Have Therefore, the guide rolls 15a and 15c and the second guide roll 15b are juxtaposed in the vertical direction (up and down direction).

  Each guide roll 15a-15c is arrange | positioned mutually parallel (or substantially parallel). Each guide roll 15a-15c is made of rubber metal, for example. Further, the correction mechanism 14 does not have a temperature control device such as a heating device and a cooling device, and guides the electrode 11 by the guide rolls 15a to 15c at room temperature without heating or cooling the electrode 11. To do. Here, “normal temperature” in the present specification refers to a temperature of 5 ° C. or more and 35 ° C. or less (20 ° C. ± 15 ° C.).

  Further, the rotational speed of the first guide roll 15a is set slightly slower than the rotational speed of the third guide roll 15c. For this reason, the electrode 11 is in close contact with the outer peripheral surface of the second guide roll 15b while being given tension along the longitudinal direction between the guide rolls 15a and 15c.

  A heating unit for heating the electrode 11 and a high-temperature tank 17 as a heating furnace are provided on the downstream side of the correction mechanism 14 in the transport direction Y1. In the internal space S as a heating space in the high-temperature tank 17, a high-temperature heat medium such as air or nitrogen gas is supplied from the outside, and the high-temperature heat medium is blown onto the electrode 11, thereby The whole is heated uniformly (or substantially uniformly).

  In the internal space S of the high-temperature tank 17, a plurality of cylindrical transport rolls 17 a that transport while supporting the electrode 11 guided by the third guide roll 15 c from below are supported so as to be rotatable around the axis. The high temperature tank 17 of the present embodiment has two transport rolls 17a. The transport rolls 17a are arranged in parallel to each other in the horizontal direction, and support the electrodes 11 in a flat state. Here, the “flat state” in this specification is intended to include not only a completely flat state but also a slightly bent or curved state. In this embodiment, each conveyance roll 17a becomes a support roll.

  A forming mechanism 19 is provided as a processing portion for forming the electrode 11 by punching the electrode 11 immediately downstream of the high temperature bath 17 in the transport direction Y1. Here, “immediately downstream of the high-temperature tank 17” is intended not to sandwich a device that changes the shape of the electrode 11 between the high-temperature tank 17 and the forming mechanism 19, for example, a cooling device, A device that does not change the shape of the electrode 11, such as an inspection device, may be interposed.

Next, the manufacturing method of the electrode 11 by the manufacturing apparatus 10 is demonstrated with the effect | action.
First, the electrode roll 11a is set on the supply roll 12a. Next, the electrode 11 supplied from the supply mechanism 12 is conveyed by the guide rolls 15a to 15c of the correction mechanism 14 to correct the warpage of the electrode 11 (correction process).

  If it demonstrates in detail, the tension | tensile_strength along a longitudinal direction will be given to the electrode 11 by the rotational speed difference of each guide roll 15a, 15c. Therefore, the electrode 11 is conveyed while being pressed against the outer peripheral surface of the second guide roll 15b and following the outer peripheral surface of the second guide roll 15b.

  For this reason, in the second guide roll 15b, the electrode 11 is warped in the opposite direction to the warped while it is in the state of the electrode roll 11a, thereby correcting the warp. In the present embodiment, the second guide roll 15b functions as a correction roll.

  Moreover, in the manufacturing apparatus 10 (correction mechanism 14), the curvature of the electrode 11 by the 2nd guide roll 15b is corrected at normal temperature. For this reason, compared with the case where correction of the curvature of the electrode 11 is performed while heating, the curvature of the electrode 11 can be corrected with a uniform temperature.

  At this time, in particular, the metal foil 11b of the electrode 11 is in a state where internal stress is generated by correcting the warp. In addition, when internal stress remains in the electrode 11, there exists a possibility that the electrode 11 may warp again or deform | transform with progress of time.

  Next, the electrode 11 whose warpage has been corrected is transported to the high temperature bath 17 and transported while heating the internal space S of the high temperature bath 17 in a flat state (heating step). Since the internal stress of the electrode 11 is reduced by being heated in the high-temperature tank 17, it is possible to suppress the electrode 11 from being deformed over time. Further, since the electrode 11 is in a flat state in the high-temperature bath 17, it is possible to suppress the occurrence of a new warp as compared with the case where the electrode 11 is heated in a deformed state.

  In the manufacturing apparatus 10, by using the high-temperature tank 17, the electrode 11 is uniformly and sufficiently heated as compared with the case where the electrode 11 is heated using, for example, a heat roll with a built-in heater. It is possible to suppress the internal stress from remaining on the surface.

  The heating temperature in the heating process, that is, the temperature of the heat medium supplied into the high-temperature tank 17 is 120 ° C. or higher. Thereby, the internal stress of the electrode 11 is reduced suitably and it can suppress that the electrode 11 deform | transforms with progress of time. The temperature of the heat medium supplied into the high-temperature tank 17 is set to a temperature lower than the thermal decomposition temperature of the binder contained in the active material layer 11 c of the electrode 11. Thereby, when the internal stress of the electrode 11 is relieved, it is possible to prevent the binder from being thermally decomposed and damaging or peeling off the active material layer 11c.

  Moreover, in the high temperature tank 17, the electrode 11 is conveyed in the state supported by each conveyance roll 17a. For this reason, it can suppress that the active material layer 11c of the electrode 11 is damaged with the fluid sprayed compared with the case where the floating type which floats and conveys the electrode 11 is employ | adopted, for example by spraying a fluid strongly.

  Next, the heated electrode 11 is conveyed to the forming mechanism 19 without being deformed in advance in the high-temperature tank 17, and the electrode 11 is punched by the forming mechanism 19 to be formed into a substantially rectangular electrode sheet (processing step). . As described above, an apparatus for changing the shape of the electrode 11 is not disposed between the high-temperature tank 17 and the forming mechanism 19. That is, in the manufacturing apparatus 10, after the internal stress is relaxed (heating process) by the high-temperature tank 17, the shape of the electrode 11 is deformed until the forming mechanism 19 punches the electrode 11 (processing process). No process is performed. For this reason, it can suppress that a curvature generate | occur | produces again in the electrode 11 which corrected the curvature and reduced the internal stress. Thereafter, the electrode sheets molded by the molding mechanism 19 are stacked with a separator sandwiched therebetween to form an electrode assembly for a lithium ion secondary battery.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The warping of the electrode 11 is corrected by the second guide roll 15b, and the internal stress is reduced by heating the electrode 11 in a flat state in the high temperature bath 17. And since the shaping | molding mechanism 19 is provided in the downstream immediately of the high-temperature tank 17, the curvature of the electrode 11 is corrected and internal stress is reduced without deforming the electrode 11 in advance. 11 can be formed. Accordingly, the warpage of the electrode 11 can be corrected and the internal stress can be reduced.

(2) The warping of the electrode 11 is corrected at room temperature. For this reason, since a curvature can be corrected in the state where the temperature of the electrode 11 is uniform, it can suppress that a curvature is corrected unevenly.
(3) In the high temperature bath 17, the electrode 11 is supported by the transport roll 17a. For this reason, it can suppress that the active material layer 11c of the electrode 11 is damaged compared with the case where the electrode 11 is conveyed by a floating type, for example.

(4) Since the electrode 11 is heated by the high-temperature tank 17, the entire electrode 11 can be heated uniformly, and internal stress remaining in a part of the electrode 11 can be suppressed.
(5) In the high temperature bath 17, the electrode 11 is heated at a temperature of 120 ° C. or higher and lower than the thermal decomposition temperature of the binder. For this reason, it can suppress that a binder thermally decomposes, reducing the internal stress of the electrode 11 by heat processing.

(6) In the processing step, the heated electrode 11 is molded without being deformed in advance. Accordingly, the warpage of the electrode 11 can be corrected and the internal stress can be reduced.
(7) Further, since the warpage of the electrode 11 is corrected and the internal stress is reduced, the electrode sheet is displaced at the edge of the electrode assembly when the electrode sheet obtained by punching the electrode 11 is laminated. Can be suppressed.

  (8) The guide rolls 15a and 15c and the second guide roll 15b are arranged so as to be aligned in the vertical direction. For this reason, compared with the case where it arrange | positions so that each guide roll 15a, 15c and the 2nd guide roll 15b may be located in a line with a horizontal direction, it can suppress that the full length of the manufacturing apparatus 10 becomes long.

The embodiment is not limited to the above, and may be embodied as follows, for example.
(Circle) as shown to Fig.2 (a), the high temperature tank 17 may have the 3 or more conveyance roll 17a. Moreover, the conveyance roll 17a may be arrange | positioned corresponding to the surface (lower surface) of the curvature direction side of the electrode 11, and the surface (upper surface) on the opposite side to curvature, respectively. Further, as shown in FIG. 2B, the transport roll 17 a may be disposed so as to correspond to the surface (upper surface) on the opposite side to the warp of the electrode 11.

  As shown in Drawing 3, the 2nd guide roll 15b may be constituted combining a plurality of rolls. For example, the second guide roll 15b may be composed of a pair of columnar second guide rolls 21a and 21b that are supported parallel to each other and rotatable about the axis. In this case, the warping of the electrode 11 is corrected while being sandwiched between the second guide rolls 21a and 21b. The outer peripheral surface of the second guide roll 21a may be formed in a concave shape along the axial direction, while the outer peripheral surface of the second guide roll 21b may be a so-called crown roll formed in a convex shape along the axial direction. . Moreover, you may make it correct the electrode 11 by rotating the 2nd guide rolls 21a and 21b, bending a center axis | shaft by feedback control.

  O You may change arrangement | positioning of each guide roll 15a-15c. For example, you may arrange | position each guide roll 15a, 15c and the 2nd guide roll 15b so that it may rank in a horizontal direction (left-right direction).

(Circle) you may provide two or more 2nd guide rolls 15b which correct the curvature of the electrode 11. FIG.
Each guide roll 15a-15c may have a coating layer such as diamond-like carbon, polytetrafluoroethylene, and molybdenum disulfide on the surface. According to this, the friction coefficient of each guide roll 15a-15c can be made small, and consumption of the energy concerning conveyance of the electrode 11 can be reduced.

  In the high temperature tank 17, you may heat by making the metal foil 11b of the electrode 11 heat-generate, for example by induction heating. Moreover, in the high temperature tank 17, a heater may be provided in the internal space S, and the electrode 11 may be heated by radiant heat.

  The forming mechanism 19 may be a device that winds the electrode 11 for the positive electrode and the electrode 11 for the negative electrode with a separator interposed therebetween, and forms each electrode 11 into an electrode assembly. According to this, when winding the electrode 11, it can suppress that the electrode 11 slip | deviates in the edge part of an electrode assembly resulting from the curvature of the electrode 11. FIG.

  (Circle) the shaping | molding mechanism 19 may be an apparatus which cut | disconnects the electrode 11 along a longitudinal direction or the width direction. According to this, it is possible to prevent the electrode 11 from being cut at a position different from the target position to be cut due to the warp of the electrode 11.

  In the high temperature tank 17, the position of each conveyance roll 17a may be changed as long as the electrode 11 can be conveyed in a flat state. For example, the transport roll 17a on the downstream side of the transport roll 17a on the upstream side in the transport direction Y1 may be disposed above or below.

O You may actualize in the manufacturing apparatus of the electrodes for electrical storage apparatuses, such as a nickel hydride secondary battery and an electrical double layer capacitor.
O You may actualize in the manufacturing apparatus of the electrode for electrical storage apparatuses used other than a vehicle.

  Y1 ... conveying direction, 10 ... manufacturing apparatus, 11 ... electrode, 11b ... metal foil, 11c ... active material layer, 14 ... straightening mechanism (correcting part), 15b ... second guide roll (correcting roll), 17 ... high temperature bath ( Heating unit, heating furnace), 17a ... transport roll, 19 ... molding mechanism (molding unit).

Claims (5)

An electrode manufacturing apparatus having an active material layer containing an active material on at least one surface of a strip-shaped metal foil,
A straightening part having a straightening roll for straightening the electrode in a direction opposite to the warping in the longitudinal direction of the electrode at room temperature;
A heating unit that is provided on the downstream side of the correction unit in the conveying direction of the electrode and heats the electrode in a flat state;
The provided immediately downstream of the heating unit in the transport direction, the electrode forming, or possess a processed portion for winding, a,
The electrode manufacturing apparatus , wherein the shape of the electrode is not deformed between the heating unit and the processing unit .   The said heating part is an electrode manufacturing apparatus of Claim 1 which has a support roll which supports the electrode conveyed by this heating part.   3. The electrode manufacturing apparatus according to claim 1, wherein the heating unit is a heating furnace having a heating space through which the electrode passes and which heats the passed electrode. 4. The active material layer includes a binder that binds the active material,
The temperature of the said heating part is 120 degreeC or more, and is less than the thermal decomposition temperature of the said binder, The manufacturing apparatus of the electrode of any one of Claims 1-3. A method for producing an electrode having an active material layer containing an active material on at least one surface of a strip-shaped metal foil,
A correction step of correcting the electrode in a direction opposite to the warpage in the longitudinal direction of the electrode at room temperature;
A heating step of heating the electrode that has corrected the warpage in a flat state;
Molding without causing the cooked electrode is pre-deformed, or the winding processing step, possess,
There is no process of changing the shape of the electrode between the heating process and the processing process .