JP5929681B2 - Battery manufacturing method and paste coating apparatus - Google Patents

Description

  The present invention relates to a battery manufacturing method including an electrode plate having an electrode base material and an electrode layer formed on the electrode base material, and a paste coating apparatus used therefor.

  In general, an electrode plate of a battery is manufactured by applying an electrode paste on an electrode base material and drying it to form an electrode layer. By the way, since an electrode paste is manufactured in a certain amount at a time, it is often stored in a storage tank for each manufacturing lot, for example. In manufacturing a large number of electrode plates using such an electrode paste, the electrode paste is continuously applied onto the electrode substrate while switching the electrode pastes of different production lots.

  Patent Document 1 discloses a coating liquid coating apparatus that can switch and apply two coating liquids. The coating liquid coating apparatus includes a coating liquid supply apparatus that is a supply source of the coating liquid, and a coating apparatus that applies the coating liquid sent from the coating liquid supply apparatus to a substrate such as a glass substrate (Patent Literature). (See Fig. 1 in Fig. 1). Among these, the coating liquid supply apparatus has two coating liquid tanks each storing the coating liquid, and is configured so that the coating liquid stored in these coating liquid tanks can be switched and fed to the coating apparatus. Yes.

JP 2011-189295 A

  However, such a coating liquid coating apparatus is used for the production of battery electrode plates, and the electrode paste is continuously used as an electrode base material while switching the supply of a plurality of electrode pastes stored in a plurality of coating liquid tanks. When applying, the electrode paste before switching and the electrode paste after switching are applied simultaneously at the same time. Here, if the viscosity of the electrode paste greatly differs before and after switching due to different production lots, the viscosity of the electrode paste inside the coating apparatus varies depending on the location when switching. Then, the fluidity of the electrode paste in the coating apparatus becomes non-uniform, and in the electrode paste in the coating apparatus, the portion with high fluidity increases the discharge amount per unit width dimension, while the portion with low fluidity is the unit. The discharge amount per width dimension is reduced.

  For this reason, the amount of application to the electrode substrate (the thickness of the coating film) is likely to be nonuniform in the width direction at the time of switching. Specifically, the thickness of the coating film may be non-uniform in the width direction, for example, the coating film becomes thick at both ends in the width direction of the coating film, while the coating film becomes thin at the center in the width direction. In particular, when the viscosity of the electrode paste is high and the variation range of the viscosity that can be taken by the electrode paste is wide, the application amount to the electrode base material is likely to be non-uniform at the time of switching. In this way, it was difficult to continuously form an electrode layer having a uniform thickness in the width direction, including when switching the supply of electrode paste. On the other hand, in order to solve this problem, if the allowable range of the viscosity of the electrode paste is limited, the yield decreases when the electrode paste is manufactured.

  The present invention has been made in view of the current situation, and even if the supply of a plurality of electrode pastes is switched, the electrode paste is continuously applied uniformly in the width direction, and the electrode layer has a uniform thickness. It aims at providing the manufacturing method of the battery which can manufacture a battery provided with an electrode plate, and the paste coating apparatus used for this.

One aspect of the present invention for solving the above-described problem is a method for manufacturing a battery including an electrode plate having an electrode base material and an electrode layer formed on the electrode base material, using a paste coating apparatus. A coating step of applying the electrode paste onto the electrode substrate, and a drying step of drying the electrode paste applied to the electrode substrate to form the electrode layer. The construction apparatus includes a plurality of storage tanks that respectively store the electrode paste, a plurality of coating units that apply the electrode paste on the electrode base material, and each of the storage tanks and the plurality of coating units. is disposed between, a buffer tank for supplying a plurality of the coated portion after temporarily storing the electrode paste supplied from the storage tank, the electrode paste supplied to a plurality of the coated portion Stir paste A buffer tank having a拌mechanism, disposed from each said reservoir tank to the supply path to the buffer tank, and a switching device for switching the electrode paste supplied to the buffer tank from the storage tank, the buffer tank Is connected to each of the plurality of storage tanks via the supply path, and to a plurality of the coating portions, respectively, and a plurality of the paste disposed at equal distances from the common paste supply port. A plurality of paste discharge ports arranged in line symmetry with respect to a virtual symmetry line passing through the common paste supply port when the buffer tank is viewed from above, the common paste supply port and between a plurality of the paste discharge port, the paste stirring mechanism will have been disposed, the coating step, the switching device Even by switching supply of the electrode paste to the buffer tank from the storage tank Te, a method for producing a battery is a step of applying said electrode paste on the electrode substrate continuously.

In this battery manufacturing method, even if the supply of a plurality of electrode pastes is switched using a paste coating apparatus including a plurality of storage tanks, a coating unit, and a switching tool, the electrode paste is continuously applied to the electrode substrate. Apply to.
Furthermore, since this paste coating apparatus has a buffer tank that temporarily stores the electrode paste between the storage tank and the coating unit, the electrode paste from the storage tank to the buffer tank is switched before and after the electrode paste is switched. Even when the supply of water temporarily decreases or stops, the supply amount of the electrode paste from the buffer tank to the coating part can be kept constant, and the electrode paste can be applied continuously.

  Furthermore, since this buffer tank has a paste agitation mechanism for agitating the electrode paste supplied to the coating section, the electrode paste supplied to the buffer tank before switching and the buffer after switching are switched at the time of switching the electrode paste. The electrode paste supplied to the tank can be stirred and mixed uniformly. As a result, even if the viscosity of the electrode paste supplied to the buffer tank before and after switching is greatly different, the change in the viscosity of the electrode paste supplied from the buffer tank to the coating portion can be moderated.

For this reason, at the time of switching, it is suppressed that the viscosity of the electrode paste varies depending on the location inside the coating part, and the non-uniformity of the fluidity of the electrode paste inside the coating part is suppressed. The non-uniform discharge amount per unit width is suppressed. Therefore, at any time, including when switching the supply of the electrode paste, the application amount of the electrode paste to the electrode substrate (the thickness of the coating film) can be made uniform in the width direction. Therefore, according to this battery manufacturing method, even if the supply of a plurality of electrode pastes is switched, the electrode paste can be continuously applied uniformly in the width direction to form an electrode layer having a uniform thickness in the width direction. And the battery using the electrode plate which has the electrode layer of uniform thickness in the above-mentioned width direction can be manufactured.
Furthermore, since the paste coating apparatus according to this battery manufacturing method has a plurality of coating portions, the electrode paste can be applied using these coating portions simultaneously. In addition, the plurality of paste discharge ports connected to the plurality of coating portions are arranged equidistant from the common paste supply port, respectively, and are arranged in line symmetry with respect to a virtual symmetry line passing through the common paste supply port. And the above-mentioned paste stirring mechanism is arrange | positioned between the common paste supply port and the some paste discharge port. For this reason, when the supply of the electrode paste is switched, the electrode paste having the same agitation and uniform viscosity can be fed from each paste discharge port to each coating portion.

The “electrode plate” may be, for example, a positive electrode plate in which a positive electrode active material layer containing a positive electrode active material is formed on a positive electrode electrode substrate, or a negative electrode active material layer containing a negative electrode active material on a negative electrode electrode substrate. The formed negative electrode plate may be used. Alternatively, a bipolar electrode plate (bipolar electrode plate) in which a positive electrode active material layer is formed on one main surface of an electrode substrate and a negative electrode active material layer is formed on the other main surface may be used.
In addition, the “battery” may include, for example, a wound-type electrode body in which a positive electrode plate and a negative electrode plate each having a belt shape are wound on each other via a separator, and each has a predetermined shape (for example, a rectangular shape). Etc.) may be provided with a stacked electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked via separators.

  Furthermore, in the battery manufacturing method described above, the paste stirring mechanism is disposed between the common paste supply port and each paste discharge port, and the buffer tank is viewed from above, and A method of manufacturing a battery having a plurality of stirrers arranged in line symmetry with respect to a virtual symmetry line, rotating the plurality of stirrers at the same rotational speed, and rotating the adjacent stirrers opposite to each other And good.

  By using the paste coating apparatus having such a paste stirring mechanism, when the supply of the electrode paste is switched, the paste is sufficiently stirred from each paste discharge port to each coating portion, and the viscosity is particularly uniform. Electrode paste can be fed.

  Furthermore, in the battery manufacturing method described above, the buffer tank may be a battery manufacturing method in which the buffer tank is line-symmetric with respect to the virtual symmetry line when viewed from above.

  By using such a paste coating apparatus having a buffer tank, when the supply of the electrode paste is switched, the electrodes are sufficiently stirred and particularly uniform in viscosity from each paste discharge port to each coating section. Can send paste.

  Furthermore, in the method for manufacturing a battery according to any one of the above, the electrode paste stored in the storage tank has a viscosity of 700 to 10,000 mPa · s, and a possible viscosity variation range is 3500 mPa · s. The battery manufacturing method described above is preferable.

  When using an electrode paste having a high viscosity of 700 to 10000 mPa · s and a fluctuation range of the viscosity of 3500 mPa · s or more (for example, an electrode paste having a possible viscosity of 1000 to 6500 mPa · s). As described above, when switching the supply of multiple electrode pastes and trying to apply continuously, the viscosity is originally high and the viscosity fluctuates for each production lot. In some cases, the viscosity of the electrode paste is greatly fluctuated. In this case, the case where the application amount to the electrode base material is not uniform in the width direction at the time of switching is particularly likely to occur.

  On the other hand, in this manufacturing method, the above-mentioned paste coating apparatus is used. For this reason, as described above, even if the viscosity of the electrode paste supplied to the buffer tank before and after switching is greatly different, the change in the viscosity of the electrode paste supplied from the buffer tank to the coating portion is moderated. can do. For this reason, at the time of switching, it is suppressed that the viscosity of the electrode paste varies depending on the location inside the coating part, and the non-uniformity of the fluidity of the electrode paste inside the coating part is suppressed. The non-uniform discharge amount per unit width is suppressed. Therefore, at any time, including when switching, the amount of electrode paste applied to the electrode substrate (the thickness of the coating film) can be made uniform in the width direction.

  Furthermore, in the battery manufacturing method described above, the amount of change in viscosity per unit time of the electrode paste supplied to the coating part is ΔP (mPa · s / s), and the unit from the coating part When the discharge amount per hour is ΔV (cc / s) and the viscosity change amount ΔQ = ΔP / ΔV (mPa · s / cc), the coating process is performed even when the electrode paste is switched. It is preferable to set the viscosity change amount ΔQ to 1.0 mPa · s / cc or less and to provide a battery manufacturing method in which the electrode paste is continuously applied onto the electrode substrate.

  Even when the supply of the electrode paste is switched in this way, by limiting the amount of change ΔQ in the electrode paste to 1.0 mPa · s / cc or less, the coating amount of the electrode paste (the thickness of the coating film) is about the width direction. It can be made more uniform.

Another aspect is a paste coating apparatus for applying an electrode paste onto an electrode base material, wherein the electrode paste is applied onto the electrode base material and a plurality of storage tanks each storing the electrode paste. A plurality of coating units are arranged between each of the storage tanks and the plurality of coating units, and after temporarily storing the electrode paste supplied from the storage tank, the plurality of coating units A buffer tank for supplying a buffer tank having a paste agitating mechanism for agitating the electrode paste supplied to a plurality of the coating units, and arranged in a supply path from each of the storage tanks to the buffer tank, e Bei and a switching device for switching the electrode paste supplied to the buffer tank from the storage tank, the buffer tank, a plurality of the storage capacitor via the supply channel And a plurality of paste discharge ports respectively connected to the plurality of coating parts and arranged at equal distances from the common paste supply port, and the buffer tank When viewed from above, the plurality of paste discharge ports are arranged symmetrically about a virtual symmetry line passing through the common paste supply port, and between the common paste supply port and the plurality of paste discharge ports, It is a paste coating apparatus in which the paste stirring mechanism is arranged .

  Since the buffer tank according to this paste coating apparatus has a paste stirring mechanism that stirs the electrode paste supplied to the coating unit, at the time of switching transition of the electrode paste, the electrode paste that was supplied to the buffer tank before switching, The electrode paste supplied to the buffer tank after the switching can be stirred and uniformly mixed. As a result, even if the viscosity of the electrode paste supplied to the buffer tank before and after switching is greatly different, the change in the viscosity of the electrode paste supplied from the buffer tank to the coating portion can be moderated.

For this reason, at the time of switching, it is suppressed that the viscosity of the electrode paste varies depending on the location inside the coating part, and the non-uniformity of the fluidity of the electrode paste inside the coating part is suppressed. The non-uniform discharge amount per unit width is suppressed. Therefore, at any time, including when switching the supply of the electrode paste, the application amount of the electrode paste to the electrode substrate (the thickness of the coating film) can be made uniform in the width direction. Therefore, if this paste coating apparatus is used, even if the supply of a plurality of electrode pastes is switched, the electrode paste can be continuously applied uniformly in the width direction to form an electrode layer having a uniform thickness in the width direction.
Furthermore, since this paste coating apparatus has a plurality of coating portions, the electrode paste can be applied using these coating portions simultaneously. In addition, the plurality of paste discharge ports connected to the plurality of coating portions are arranged equidistant from the common paste supply port, respectively, and are arranged in line symmetry with respect to a virtual symmetry line passing through the common paste supply port. And the above-mentioned paste stirring mechanism is arrange | positioned between the common paste supply port and the some paste discharge port. For this reason, when the supply of the electrode paste is switched, the electrode paste having the same agitation and uniform viscosity can be fed from each paste discharge port to each coating portion.

1 is a perspective view of a lithium ion secondary battery according to an embodiment. 1 is a longitudinal sectional view of a lithium ion secondary battery according to an embodiment. It is an expanded view of an electrode body which concerns on embodiment and shows the state which mutually accumulated the positive electrode plate and the negative electrode plate through the separator. It is explanatory drawing which concerns on embodiment and shows a paste coating apparatus. It is explanatory drawing which concerns on embodiment and shows the buffer tank seen from upper direction. It is a graph which shows the relationship between time and the viscosity of the positive electrode paste supplied to a coating die | dye at the time of the transfer transition of the positive electrode paste from which a viscosity differs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a lithium ion secondary battery 10 (hereinafter also simply referred to as battery 10). FIG. 3 shows the electrode body 30. In the following description, the thickness direction BH, the width direction CH, and the height direction DH of the battery 10 are defined as the directions shown in FIGS. 1 and 2. The battery 10 is a square sealed battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle. The battery 10 includes a rectangular parallelepiped battery case 20, a flat wound electrode body 30 accommodated in the battery case 20, a positive terminal 60 and a negative terminal 70 supported by the battery case 20, and the like. Has been. Further, a non-aqueous electrolyte solution 27 is held in the battery case 20.

  Among these, the electrode body 30 is accommodated in the battery case 20 in a state of being laid down so that its axis (winding axis) is parallel to the width direction CH of the battery 10 (see FIG. 2). This electrode body 30 has a belt-like positive electrode plate 31 and a belt-like negative electrode plate 41 which are stacked on each other via two belt-like separators 51 and 51 made of a resin porous film (see FIG. 3). It is wound around and compressed into a flat shape. A part of the positive electrode plate 31 in the width direction protrudes from the separators 51, 51 to one side in the axial direction (leftward in FIG. 2, upper in FIG. 3) in a spiral shape and is connected to the positive electrode terminal 60. (Welding). A part of the negative electrode plate 41 in the width direction protrudes from the separators 51, 51 in a spiral shape on the other side in the axial direction (right side in FIG. 2, downward in FIG. 3). Connected (welded).

  The positive electrode plate (electrode plate) 31 has a strip-like positive electrode foil (electrode substrate) 32 made of aluminum as a core material. Of the front and back surfaces of the positive electrode foil 32, a part of the width direction (vertical direction in FIG. 3) (downward in FIG. 3) extends in a strip shape in the longitudinal direction (horizontal direction in FIG. 3). Positive electrode active material layers (electrode layers) 33 and 33 are formed. The positive electrode active material layer 33 is formed of a positive electrode active material, a conductive material, and a binder. In this embodiment, lithium-cobalt-nickel-manganese composite oxide is used as the positive electrode active material, acetylene black (AB) is used as the conductive material, and polyvinylidene fluoride (PVDF) is used as the binder.

  The negative electrode plate 41 has a strip-shaped negative electrode foil 42 made of copper as a core material. Each of the front and back surfaces of the negative electrode foil 42 extends in a strip shape in the longitudinal direction (left and right direction in FIG. 3) on a part (upward in FIG. 3) in the width direction (up and down direction in FIG. 3). Negative electrode active material layers 43 and 43 are formed. The negative electrode active material layer 43 is formed of a negative electrode active material, a thickener, and a binder. In this embodiment, natural graphite is used as the negative electrode active material, carboxymethyl cellulose (CMC) is used as the thickener, and styrene butadiene rubber (SBR) is used as the binder.

  Next, a method for manufacturing the battery 10 will be described. First, the positive electrode plate 31 is manufactured. That is, a strip-shaped positive electrode foil 32x having a dimension in which a plurality of strip-shaped positive electrode foils 32 are connected in the longitudinal direction is prepared. A positive electrode paste (electrode paste) AP in which a positive electrode active material, a conductive material, and a binder are dispersed in a solvent (specifically, N-methylpyrrolidone (NMP)) is prepared. This positive electrode paste AP has a viscosity of 700 to 10000 mPa · s, and a possible viscosity fluctuation range is 3500 mPa · s or more. Specifically, the possible viscosity of the positive electrode paste AP of the present embodiment is 1000 to 6500 mPa · s. The viscosity of the positive electrode paste AP and the viscosity of the negative electrode paste BP to be described later were both measured using a B-type viscometer under the conditions of 25 ° C. and 1 rpm.

  And in a coating process, positive electrode paste AP is apply | coated on a part of width direction among one main surfaces of the positive electrode foil 32x using the paste coating apparatus 100 (refer FIG. 4). The paste coating apparatus 100 includes a plurality (two in the present embodiment) of storage tanks 111 and 112, a plurality (two in the present embodiment) of coating dies (coating portions) 121 and 122, and a buffer tank. 131, a switching tool 141, and three pumps 151, 152, and 153, which are connected via pipes 161 to 168.

Among these, the storage tanks (the first storage tank 111 and the second storage tank 112) store the positive electrode paste AP. In the present embodiment, the positive electrode paste AP stored in the first storage tank 111 is referred to as a first positive electrode paste AP1, and the positive electrode paste AP stored in the second storage tank 112 is referred to as a second positive electrode paste AP2.
The coating dies (the first coating die 121 and the second coating die 122) discharge the positive electrode paste AP and apply it to the positive electrode foil 32x.

The buffer tank 131 is disposed between the storage tanks 111 and 112 and the coating dies 121 and 122, and is connected to these via pipes 161 to 168 as will be described later. The buffer tank 131 temporarily stores the positive electrode paste AP supplied from the storage tanks 111 and 112 and then supplies the positive electrode paste AP to the coating dies 121 and 122. The buffer tank 131 has a bottomed cylindrical shape having a substantially oval opening when viewed from above (see FIG. 5), and is symmetric with respect to a virtual symmetry line LX, which will be described later.
Hereinafter, the positive electrode paste AP supplied from the storage tanks 111 and 112 to the buffer tank 131 will be referred to as the positive electrode paste APa, the positive electrode paste AP supplied from the buffer tank 131 to the coating dies 121 and 122, and the positive electrode paste APb. say.

  The buffer tank 131 has one common paste supply port 132 to which the positive electrode paste APa is supplied, and a plurality (two in this embodiment) of paste discharge ports (first paste discharge port 133 and the second paste discharge port) for discharging the positive electrode paste APb. A second paste discharge port 134) is provided. Among these, the common paste supply port 132 is provided on the side surface 131 c of the buffer tank 131. Specifically, when the buffer tank 131 is viewed from above (see FIG. 5), the common paste supply port 132 is located at a position where the buffer tank 131 is line-symmetric with respect to the virtual symmetry line LX passing through the common paste supply port 132. Is provided.

  On the other hand, the first paste discharge port 133 and the second paste discharge port 134 are respectively provided on the bottom surface 131 d of the buffer tank 131. Specifically, the first paste discharge port 133 and the second paste discharge port 134 are arranged at an equal distance from the common paste supply port 132, respectively. That is, the distance L1 from the common paste supply port 132 to the first paste discharge port 133 is equal to the distance L2 from the common paste supply port 132 to the second paste discharge port 134 (L1 = L2). Further, when the buffer tank 131 is viewed from above, the first paste discharge port 133 and the second paste discharge port 134 are arranged symmetrically with respect to the virtual symmetry line LX passing through the common paste supply port 132.

  The buffer tank 131 and the coating dies 121 and 122 are connected via a supply path 160 constituted by pipes 161 to 164. Specifically, a pipe 164 is connected to the common paste supply port 132 of the buffer tank 131, and is connected to a pump 151 that feeds the positive electrode paste APa toward the buffer tank 131 (see FIG. 4). Further, the pump 151 is connected to a switching tool 141 described later via a pipe 163. Further, the switching tool 141 is connected to the first storage tank 111 via a pipe 161 and is connected to the second storage tank 112 via a pipe 162.

  In addition, a pipe 165 is connected to the first paste discharge port 133 and is connected to a pump 152 that feeds the positive electrode paste APb from the buffer tank 131. Further, the pump 152 is connected to the first coating die 121 via a pipe 167. A pipe 166 is connected to the second paste discharge port 134 and is connected to a pump 153 that feeds the positive electrode paste APb from the buffer tank 131. Further, the pump 153 is connected to the second coating die 122 via a pipe 168.

  Between the common paste supply port 132 and the paste discharge ports 133 and 134, the positive electrode paste APa supplied from the storage tanks 111 and 112 (common paste supply port 132) is stirred, and the coating dies 121 and 122 (paste) A paste stirring mechanism 136 for supplying to the discharge ports 133, 134) is arranged (see FIG. 5). Specifically, the paste stirring mechanism 136 includes a first stirring bar 137 disposed between the common paste supply port 132 and the first paste discharge port 133, a common paste supply port 132, and a second paste discharge port 134. And a second stirrer 138 disposed between the two. The first stirrer 137 and the second stirrer 138 are arranged so that their rotation axes are perpendicular (vertical) to the bottom surface 131d of the buffer tank 131, respectively. Further, the first stirrer 137 and the second stirrer 138 are arranged symmetrically with respect to the above-described virtual symmetry line LX passing through the common paste supply port 132 when the buffer tank 131 is viewed from above. In addition, the first stirrer 137 and the second stirrer 138 rotate at the same rotational speed as each other and reversely rotate from each other.

  Next, the switching tool 141 will be described (see FIG. 4). The switching tool 141 is a three-way valve, and is arranged in the supply path 160 from the two storage tanks 111 and 112 to the buffer tank 131 as described above. The switching tool (three-way valve) 141 switches the storage tank connected to the buffer tank 131 to one of the first storage tank 111 and the second storage tank 112 and supplies the positive electrode paste AP supplied to the buffer tank 131 to the first. Switching to either the positive electrode paste AP1 or the second positive electrode paste AP2.

  In the coating process, even when the supply of the positive electrode paste APa from the storage tanks 111 and 112 to the buffer tank 131 is switched by the switching tool 141 using the paste coating apparatus 100, the positive electrode paste APb is continuously applied to the positive electrode foil. Apply on 32x. At that time, since the paste coating apparatus 100 includes the two coating dies 121 and 122 as described above, as will be described later, a part of the main surface on the opposite side of the positive electrode foil 32x on a part in the width direction. In addition, the positive electrode paste APb can be applied. The two coating dies 121 and 122 may be used to simultaneously apply the positive electrode paste AP to one main surface of the two positive electrode foils 32x and 32x. Alternatively, the two coating dies 121 and 122 may simultaneously form two positive electrode active material layers on a positive electrode foil having a dimension in which a plurality of (for example, four) positive electrode foils 32x are connected in the width direction. You may use for.

  In this coating step, each of the pumps 151 to 153 is operated, and the first positive electrode paste AP1 stored in the first storage tank 111 is first passed through the pipes 161 to 164, the buffer tank 131, and the pipes 165 to 168. The solution is fed to the coating dies 121 and 122 and applied from the coating dies 121 and 122 onto a part of one main surface of the positive electrode foil 32x in the width direction. At this time, in the present embodiment, the paste stirring mechanism 136 in the buffer tank 131 is operated to stir the positive electrode paste AP (first positive electrode paste AP1) in the buffer tank 131. This is for reliably preventing the components of the positive electrode paste AP from settling in the buffer tank 131.

  Thereafter, when the first positive electrode paste AP1 in the first storage tank 111 runs out, the switching tool 141 is operated to switch the connection with the buffer tank 131 from the first storage tank 111 to the second storage tank 112. The positive electrode paste APa supplied to 131 is switched from the first positive electrode paste AP1 to the second positive electrode paste AP2. Since the buffer tank 131 temporarily stores the positive electrode paste AP, even when the supply of the positive electrode paste APa from the storage tanks 111 and 112 to the buffer tank 131 temporarily decreases or stops during this switching transition. The supply amount of the positive electrode paste APb from the buffer tank 131 to the coating dies 121 and 122 can be kept constant.

  In addition, even at the time of switching, the paste stirring mechanism 136 in the buffer tank 131 is continuously operated to stir the positive electrode paste AP in the buffer tank 131. As a result, the first positive electrode paste AP1 supplied to the buffer tank 131 before switching and the second positive electrode paste AP2 supplied to the buffer tank 131 after switching are stirred and mixed uniformly. Then, the mixed positive electrode paste APb is fed toward the coating dies 121 and 122 and applied onto the positive electrode foil 32x by the coating dies 121 and 122. For this reason, as will be described later, even if the viscosity of the first positive electrode paste AP1 and the second positive electrode paste AP2 is greatly different, the viscosity of the positive electrode paste APb supplied from the buffer tank 131 to the coating dies 121 and 122 is reduced. Change can be moderated. The ratio of the first positive electrode paste AP1 in the positive electrode paste AP in the buffer tank 131 gradually decreases, while the ratio of the second positive electrode paste AP2 gradually increases.

  FIG. 6 shows the change over time in the viscosity Pc of the positive electrode paste APb supplied to the coating dies 121 and 122 when switching is performed for the positive electrode pastes AP1 and AP2 having different viscosities Pc1 and Pc2 (Pc1 <Pc2). . If the positive electrode paste AP in the buffer tank 131 is not stirred without operating the paste stirring mechanism 136, the supply of the positive electrode paste APa is immediately after switching from the first positive electrode paste AP1 to the second positive electrode paste AP2. The viscosity Pc of the positive electrode paste APb supplied from the buffer tank 131 to the coating dies 121 and 122 rapidly increases.

  On the other hand, in this embodiment, the paste stirring mechanism 136 is operated and the positive electrode paste AP in the buffer tank 131 is stirred by the first stirring bar 137 and the second stirring bar 138. Therefore, even when the first positive electrode paste AP1 is switched to the second positive electrode paste AP2 having a higher viscosity, the viscosity Pc of the positive electrode paste APb supplied from the buffer tank 131 to the coating dies 121 and 122 increases only slowly. do not do.

  After the supply of the positive electrode paste APa to the buffer tank 131 is switched from the first positive electrode paste AP1 to the second positive electrode paste AP2, while using the second positive electrode paste AP2 stored in the second storage tank 112, The first storage tank 111 is replaced with another storage tank in which the positive electrode paste AP is stored. Alternatively, instead of replacing the storage tank, the first storage tank 111 is supplemented with the positive electrode paste AP.

  Thereafter, when the remaining amount of the second positive electrode paste AP2 in the second storage tank 112 is exhausted, the switching tool 141 is operated again, and the connection with the buffer tank 131 is changed from the second storage tank 112 to the first storage tank 111. The positive electrode paste APa to be switched and supplied to the buffer tank 131 is switched from the second positive electrode paste AP2 to the first positive electrode paste AP1. Then, the first positive electrode paste AP1 in the first storage tank 111 is applied onto the positive electrode foil 32x. Thus, in the coating process of this embodiment, the positive electrode paste APb is continuously applied onto the positive electrode foil 32x while switching the supply of the plurality of positive electrode pastes APa.

  In this coating process, even when the positive electrode paste APa is switched, the viscosity change amount ΔQ is set to 1.0 mPa · s / cc or less, and the positive electrode paste APb is continuously applied onto the positive electrode foil 32x. The viscosity change amount ΔQ is obtained as follows. That is, the viscosity change amount ΔP (mPa · s / s) per unit time of the positive electrode paste APa supplied to the coating dies 121 and 122 is obtained. Further, a discharge amount ΔV (cc / s) per unit time from the coating dies 121 and 122 is obtained. Then, the viscosity change amount ΔQ (mPa · s / cc) is calculated from ΔQ = ΔP / ΔV. In order to adjust the value of the viscosity change amount ΔQ, the viscosity difference between the two positive electrode pastes AP1 and AP2, the discharge amount ΔV from the coating dies 121 and 122, and the like may be appropriately changed.

  After the coating process, in the drying process, the positive electrode paste APb applied to the positive electrode foil 32x is dried with hot air, and a strip-shaped positive electrode active material having a dimension in which a plurality of strip-shaped positive electrode active material layers 33 are connected in the longitudinal direction. Layer 33x is formed.

  Next, the above-described coating process is performed again, and the positive electrode paste AP is applied to the main surface on the opposite side of the positive electrode foil 32x on a part in the width direction using the paste coating apparatus 100. Furthermore, a drying process is performed, and the positive electrode paste AP applied to the positive electrode foil 32x is dried with hot air to form the positive electrode active material layer 33x. Thereafter, the positive electrode active material layers 33x and 33x are compressed by a pressure roll to increase the density. Then, this positive electrode plate is cut into a predetermined dimension and separated. Thus, the positive electrode plate 31 is formed.

  Separately, the negative electrode plate 41 is manufactured. That is, a strip-shaped negative electrode foil 42x having a dimension in which a plurality of strip-shaped negative electrode foils 42 are connected in the longitudinal direction is prepared. Further, a negative electrode paste BP in which a negative electrode active material, a thickener, and a binder are dispersed in a solvent (specifically, water) is prepared. And this negative electrode paste BP is apply | coated on one part main surface of the negative electrode electrode foil 42x on a part of width direction, this is dried with a hot air, and the strip | belt-shaped negative electrode active material layer 43 has two or more in the longitudinal direction. A strip-shaped negative electrode active material layer 43x having a connected dimension is formed (see FIG. 3). Similarly, the negative electrode paste BP is applied on a part of the main surface on the opposite side of the negative electrode foil 42x in the width direction, and dried with hot air to form the negative electrode active material layer 43x. Thereafter, the negative electrode active material layers 43x and 43x are compressed by a pressure roll to increase the density. Thereafter, the negative electrode plate is cut into a predetermined size and separated. Thus, the negative electrode plate 41 is formed.

Next, two strip-shaped separators 51 are prepared, and the above-described positive electrode plate 31 and negative electrode plate 41 are overlapped with each other through the separators 51 and 51 (see FIG. 3), and wound around the axis using a winding core. . Thereafter, the electrode body 30 is formed by compressing it into a flat shape.
Separately, a rectangular plate-like lid member 23 (see FIG. 2) of the battery case 20 is prepared, and a positive electrode terminal 60 and a negative electrode terminal 70 are fixed to the lid member 23, respectively. Thereafter, a bottomed rectangular tube-shaped main body member 21 of the battery case 20 is prepared, and after the electrode body 30 is accommodated in the main body member 21, the main body member 21 and the lid member 23 are laser-welded to form the battery case 20. Form. Thereafter, the electrolytic solution 27 is injected into the battery case 20. Thereafter, the battery is subjected to initial charging and various inspections. Thus, the battery 10 is completed.

As described above, in the method for manufacturing the battery 10, the paste coating apparatus 100 including the plurality of storage tanks 111, 112, the coating dies 121, 122, and the switching tool 141 is used. Even when the supply is switched, the positive electrode paste APb is continuously applied onto the positive electrode foil 32x.
Further, since the paste coating apparatus 100 includes a buffer tank 131 that temporarily stores the positive electrode paste AP between the storage tanks 111 and 112 and the coating dies 121 and 122, before and after switching of the positive electrode paste AP. Even when the supply of the positive electrode paste APa from the storage tanks 111 and 112 to the buffer tank 131 temporarily decreases or stops, the supply amount of the positive electrode paste APb from the buffer tank 131 to the coating dies 121 and 122 is kept constant. The positive electrode paste APb can be applied continuously.

  Furthermore, since this buffer tank 131 has a paste stirring mechanism 136 for stirring the positive electrode paste APb supplied to the coating dies 121 and 122, it is supplied to the buffer tank 131 before switching when the positive electrode paste APa is switched. The positive electrode paste APa and the positive electrode paste APa supplied to the buffer tank 131 after the switching can be stirred and mixed uniformly. Thereby, even if the viscosity of the positive electrode paste APa supplied to the buffer tank 131 before and after switching is greatly different, the change in the viscosity of the positive electrode paste APb supplied from the buffer tank 131 to the coating dies 121 and 122 is changed. It can be relaxed.

  For this reason, at the time of switching, the viscosity of the positive electrode paste APb in the coating dies 121 and 122 is suppressed from being different depending on the location, and the non-uniformity of the fluidity of the positive electrode paste APb in the coating dies 121 and 122 is suppressed. Therefore, nonuniform discharge amount per unit width dimension due to the location from the coating dies 121 and 122 is suppressed. Therefore, at any time including the transition of the supply of the positive electrode paste APa, the application amount (the thickness of the coating film) of the positive electrode paste APb to the positive electrode foil 32x can be made uniform in the width direction. Therefore, even if the supply of the plurality of positive electrode pastes APa is switched, the positive electrode paste APb can be continuously applied uniformly in the width direction to form the positive electrode active material layer 33x having a uniform thickness in the width direction. And the battery 10 using the positive electrode plate 31 which has the positive electrode active material layer 33 of uniform thickness in the above-mentioned width direction can be manufactured.

  Furthermore, since the paste coating apparatus 100 according to the present embodiment includes the plurality of coating dies 121 and 122, the positive electrode paste APb can be applied using these coating dies 121 and 122 simultaneously. In addition, the plurality of paste discharge ports 133 and 134 connected to the plurality of coating dies 121 and 122 are arranged at equal distances from the common paste supply port 132, respectively, and about the virtual symmetric line LX passing through the common paste supply port 132. They are arranged in line symmetry. A paste stirring mechanism 136 is disposed between the common paste supply port 132 and the plurality of paste discharge ports 133 and 134. For this reason, when the supply of the positive electrode paste APa is switched, the positive electrode paste APb which is similarly stirred and has a uniform viscosity can be fed from the respective paste discharge ports 133 and 134 to the respective coating dies 121 and 122.

The paste stirring mechanism 136 is disposed between the common paste supply port 132 and each paste discharge port 133, 134, and is disposed symmetrically about the virtual symmetry line LX when the buffer tank 131 is viewed from above. Two stir bars 137, 138. The stirrers 137 and 138 are rotated at the same rotational speed and are rotated in the opposite directions. By using the paste coating apparatus 100 having such a paste agitating mechanism 136, when the supply of the positive electrode paste APa is switched, it is sufficient from the respective paste discharge ports 133, 134 toward the respective coating dies 121, 122. The positive electrode paste APb having a particularly uniform viscosity can be fed.
Further, the buffer tank 131 is line-symmetric with respect to the virtual symmetry line LX when viewed from above. By using the paste coating apparatus 100 having such a buffer tank 131, when the supply of the positive electrode paste APa is switched, the paste coating apparatus 100 is sufficiently provided from the respective paste discharge ports 133, 134 toward the respective coating dies 121, 122. The positive electrode paste APb which is stirred and has a particularly uniform viscosity can be fed.

  In the present embodiment, the positive electrode paste AP having a high viscosity of 700 to 10000 mPa · s and a fluctuation range that the viscosity can take is 3500 mPa · s or more. On the other hand, the paste coating apparatus 100 is used. For this reason, even if the viscosity of the positive electrode paste APa supplied to the buffer tank 131 varies greatly before and after the switching, the viscosity of the positive electrode paste APb supplied from the buffer tank 131 to the coating dies 121 and 122 is changed. It can be relaxed. For this reason, at the time of switching, the viscosity of the positive electrode paste APb in the coating dies 121 and 122 is suppressed from being different depending on the location, and the non-uniformity of the fluidity of the positive electrode paste APb in the coating dies 121 and 122 is suppressed. Therefore, nonuniform discharge amount per unit width dimension due to the location from the coating dies 121 and 122 is suppressed. Therefore, at any time including when switching, the application amount (the thickness of the coating film) of the positive electrode paste APb to the positive electrode foil 32x can be made uniform in the width direction.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the embodiment, the present invention is applied to manufacture of the positive electrode plate 31, but the present invention may be applied to manufacture of the negative electrode plate 41.
In the embodiment, the three-way valve is exemplified as the switching tool 141 for switching the supply of the positive electrode paste AP, but is not limited thereto. For example, instead of the three-way valve 141, a two-way valve is provided in each of the pipe 161 and the pipe 162, and the supply of the positive electrode paste AP can be switched by controlling the opening and closing of these valves.

10 Lithium ion secondary battery (battery)
30 Electrode body 31 Positive electrode plate (electrode plate)
32 Positive electrode foil (electrode substrate)
32x Positive electrode foil 33 (before individual division) Positive electrode active material layer (electrode layer)
33x Positive active material layer 41 (before separation) Negative electrode plate 100 Paste coating device 111 First storage tank 112 Second storage tank 121 First coating die (coating portion)
122 2nd coating die (coating part)
131 Buffer tank 132 Common paste supply port 133 First paste discharge port 134 Second paste discharge port 136 Paste stirring mechanism 137 First stirrer 138 Second stirrer 141 Switching tool AP Positive electrode paste AP1 First positive electrode paste AP2 Second positive electrode paste APa Positive electrode paste APb (supplied from storage tank to buffer tank) APb (supplied from buffer tank to coating die) Positive electrode paste L1, L2 Distance LX Virtual symmetry line

Claims (5)

A method for producing a battery comprising an electrode plate having an electrode substrate and an electrode layer formed on the electrode substrate,
Using a paste coating device, a coating process for applying an electrode paste onto the electrode substrate;
Drying the electrode paste applied to the electrode substrate to form the electrode layer, and
The paste coating apparatus is
A plurality of storage tanks each storing the electrode paste;
A plurality of coating portions for applying the electrode paste on the electrode substrate;
A buffer tank disposed between each of the storage tanks and the plurality of coating units, and temporarily supplying the electrode paste supplied from the storage tank to the plurality of coating units. A buffer tank having a paste stirring mechanism for stirring the electrode paste supplied to a plurality of the coating units;
A switching tool that is disposed in a supply path from each of the storage tanks to the buffer tank, and that switches the electrode paste supplied from the storage tank to the buffer tank,
The buffer tank is
One common paste supply port connected to the plurality of storage tanks via the supply path;
A plurality of paste discharge ports respectively connected to the plurality of coating portions and arranged at equal distances from the common paste supply port,
When the buffer tank is viewed from above, the plurality of paste discharge ports are arranged symmetrically with respect to a virtual symmetry line passing through the common paste supply port,
The paste stirring mechanism is arranged between the common paste supply port and the plurality of paste discharge ports,
The coating process includes
A method for manufacturing a battery, which is a step of continuously applying the electrode paste onto the electrode base material even if the supply of the electrode paste from the storage tank to the buffer tank is switched by the switching tool. A battery manufacturing method according to claim 1 , comprising:
The paste stirring mechanism is
A plurality of stirrers arranged between the common paste supply port and each of the paste discharge ports, and arranged in line symmetry with respect to the virtual symmetry line when viewed from above the buffer tank;
A method for manufacturing a battery, wherein the plurality of stirring bars are rotated at the same rotational speed, and the adjacent stirring bars are rotated in the opposite directions. A method of manufacturing a battery according to claim 2 ,
The buffer tank is
A method for producing a battery, which is viewed from above and is in a line-symmetric form with respect to the virtual symmetry line. It is a manufacturing method of the battery as described in any one of Claims 1-3 , Comprising:
The electrode paste stored in the storage tank is
A method for producing a battery having a viscosity of 700 to 10000 mPa · s and a variable viscosity range of 3500 mPa · s or more. A paste coating apparatus for applying an electrode paste onto an electrode substrate,
A plurality of storage tanks each storing the electrode paste;
A plurality of coating portions for applying the electrode paste on the electrode substrate;
A buffer tank disposed between each of the storage tanks and the plurality of coating units, and temporarily supplying the electrode paste supplied from the storage tank to the plurality of coating units. A buffer tank having a paste stirring mechanism for stirring the electrode paste supplied to a plurality of the coating units;
Arranged from the storage tank of each supply passage to said buffer tank, Bei example and a switching device for switching the electrode paste supplied to the buffer tank from the storage tank,
The buffer tank is
One common paste supply port connected to the plurality of storage tanks via the supply path;
A plurality of paste discharge ports respectively connected to the plurality of coating portions and arranged at equal distances from the common paste supply port,
When the buffer tank is viewed from above, the plurality of paste discharge ports are arranged symmetrically with respect to a virtual symmetry line passing through the common paste supply port,
The paste coating apparatus , wherein the paste stirring mechanism is disposed between the common paste supply port and the plurality of paste discharge ports .

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