JP5454295B2 - Secondary battery manufacturing method and secondary battery electrode plate manufacturing apparatus - Google Patents

Description

The present invention relates to an electrode plate manufacturing apparatus manufacturing method and a secondary battery of the secondary batteries. More particularly, it relates to a manufacturing apparatus for a manufacturing method and the electrode plate of the secondary batteries comprising a drying the plurality of paste layers in the electrode core member electrode plate having bound.

  Secondary batteries are used in various fields such as electronic devices such as mobile phones and personal computers, vehicles such as hybrid vehicles and electric vehicles. Such a secondary battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. Moreover, it is common to use the electrode body which laminated | stacked the positive electrode plate, the negative electrode plate, and the separator which insulates them.

  The electrode plates (positive electrode plate and negative electrode plate) used for the electrode bodies laminated in this way are prepared by applying a composite material containing an active material to a metal foil serving as an electrode core material and then drying it. Among these electrode plates, there are those in which a plurality of paste layers are applied to an electrode core material and dried. In order to produce an electrode plate coated and dried with such a plurality of paste layers, the following coating drying method is generally used. First, the first layer is applied to the electrode core material to be a base material and then dried. Subsequently, the second layer is coated on the dried first coating layer and dried. Thus, coating and drying are sequentially repeated (see paragraph [0007] of Patent Document 1).

  As described above, in the coating and drying method in which coating and drying are sequentially repeated, when a plurality of layers having the same composition are formed, the adhesion between the layers is considered to be good. In addition, when a plurality of layers having different compositions are formed, it is said that different physical properties can be satisfied simultaneously (see paragraph [0004] etc. of Patent Document 1).

JP-A-8-050893

  In the technique described in Patent Document 1, it is possible to form a multilayer coating layer so that the paste does not mix between the layers by sequentially repeating coating and drying from the substrate side. However, in these techniques, it is necessary to repeat the coating and drying process as many times as the number of layers forming coating and drying. That is, as the number of layers increases, the number of processes increases. If such a coating drying method is used, the productivity of the electrode plate is low.

The present invention has been made to solve the above-described problems of the prior art. That it is an object, as well as to create an electrode plate is dried by applying a paste layer of a multilayer on the electrode core member, the high secondary battery electrode plates productive manufacturing how AND ITS electrode plate It is to provide a manufacturing apparatus.

  The secondary battery manufacturing method of the present invention made for the purpose of solving this problem includes a coating step of applying a paste layer to a positive electrode core material or a negative electrode core material, and a paste layer applied in the coating step. An electrode body creating process for forming a positive electrode plate or a negative electrode plate by drying, a positive electrode plate and a negative electrode plate dried in the drying step, and a separator for insulating them, and an electrode body creating step And a battery assembling step of injecting an electrolyte solution into the battery container while inserting the electrode body prepared in step 1 into the battery container. In the coating process, at least one of the positive electrode core material and the negative electrode core material is coated with two or more paste layers without drying each time, and in the drying process, two or more undried paste layers are applied. When drying, the temperature of the paste layer closer to the outermost layer of the two or more undried paste layers is increased, and the side farther from the outermost layer of the two or more undried paste layers. As the paste layer becomes lower, the temperature of the paste layer is lowered. In such a secondary battery manufacturing method, two or more undried paste layers can be dried in one step. Therefore, productivity is high. Moreover, there is no possibility that the pastes are mixed with each other at the interface between the layers.

  The method for manufacturing a secondary battery as described above, wherein, in at least a part of the drying step, when the two or more undried paste layers are dried, the outermost layer paste in the two or more undried paste layers The outermost paste layer may be heated only from the layer side. This is because each paste layer is dried while the temperature of the paste layer on the outermost layer side is high.

  The method for manufacturing a secondary battery as described above, wherein, in at least a part of the drying step, when the two or more undried paste layers are dried, the outermost layer paste in the two or more undried paste layers Heat the outermost paste layer from the front side of the layer, and heat the surface of the two or more undried paste layers from the opposite side of the outermost paste layer to the opposite side of the outermost layer weaker than the heating from the front side . Even if it does in this way, it is because it does not change that each paste layer is dried in the state where the temperature of the paste layer of the outermost layer side is high.

  The method for manufacturing a secondary battery as described above, wherein, in at least a part of the drying step, when the two or more undried paste layers are dried, the outermost layer paste in the two or more undried paste layers While heating the outermost paste layer from the front side of the layer, the surface opposite to the outermost layer from the opposite side of the outermost paste layer in the two or more undried paste layers may be cooled. This is because each paste layer is dried while the temperature of the paste layer on the outermost layer side is higher.

  In the method for manufacturing a secondary battery as described above, in the coating process, when two or more paste layers are applied without being dried each time, the outermost layer of the two or more paste layers is coated. As the volatile solvent in the paste layer that is not, it is more preferable to use a solvent whose boiling point under atmospheric pressure is equal to or higher than the boiling point under atmospheric pressure of the volatile solvent in the paste layer above the paste layer. This is because the drying speed of the paste layer located in the upper layer becomes faster. This is because the upper paste layer is sequentially dried.

  In the method of manufacturing a secondary battery as described above, in at least a part of the drying process, when drying two or more undried paste layers, the temperature of the atmosphere located above the outermost paste layer is It is even better if the temperature is higher than the temperature of the atmosphere located below the positive electrode core material or the negative electrode core material. This is because each paste layer is dried while the temperature of the paste layer on the outermost layer side is higher.

  In the method of manufacturing a secondary battery as described above, in at least a part of the drying process, when drying two or more undried paste layers, the temperature of the atmosphere located above the outermost paste layer is It is more preferable that the temperature is higher by 50 ° C. or more than the temperature of the atmosphere located below the positive electrode core material or the negative electrode core material. This is because the drying speed of the paste layer located in the upper layer is further increased. This is because the upper paste layer is sequentially dried.

  In the method for manufacturing a secondary battery as described above, in the drying step, the degree of heating from the outermost layer side of the undried paste layer and the heating from the opposite side of the outermost layer are increased in the initial stage of the drying step. It is better that the difference between the degree of heating and the degree of heating from the outermost layer side of the undried paste layer and the degree of heating from the opposite side of the outermost layer are smaller in the later stage of the drying process. This is because the upper paste layer can be dried in order, and the lower paste layer can be reliably dried.

The secondary battery electrode plate manufacturing apparatus according to the present invention includes an unwinding portion for unwinding the electrode core material of the electrode plate of the secondary battery, and two or more paste layers on the electrode core material in an undried state. The temperature of the paste layer is increased as the paste layer closest to the outermost layer among the two or more undried paste layers is coated with the coating layer to be applied in layers. In the two or more undried paste layers, the paste layer farthest from the outermost layer is wound with a drying oven for drying while lowering the temperature of the paste layer, and an electrode core material with the coating layer dried. And a take-up portion to take .

In at least a part of the drying furnace in the electrode plate manufacturing apparatus for a secondary battery described above, a heating device for heating toward the transport path is disposed above the transport path of the coated electrode core material. It is preferable that a cooling device for cooling toward the transport path is disposed below the transport path. Such an electrode plate manufacturing apparatus can dry two or more undried paste layers in one step. Therefore, productivity is high. Moreover, there is no possibility that the pastes are mixed with each other at the interface between the layers.

According to the present invention, an electrode plate is produced by applying a multi-layer paste layer to an electrode core material and drying, and a method of manufacturing a secondary battery with high productivity of the electrode plate and manufacturing of the electrode plate of the secondary battery A device is provided.

It is sectional drawing for demonstrating the battery manufactured by the manufacturing method of the secondary battery which concerns on this invention. It is a perspective view for demonstrating the winding electrode body of the battery manufactured by the manufacturing method of the secondary battery which concerns on this invention. It is an expanded view for demonstrating the winding structure of the winding electrode body of the battery manufactured by the manufacturing method of the secondary battery which concerns on this invention. It is a cross-sectional perspective view for demonstrating the structure of the positive electrode plate of the battery manufactured by the manufacturing method of the secondary battery which concerns on this invention. It is a cross-sectional perspective view for demonstrating the structure of the negative electrode plate of the battery manufactured by the manufacturing method of the secondary battery which concerns on 1st, 2nd, 4th embodiment. It is a conceptual diagram for demonstrating the cooling method of the paste layer which concerns on 1st Embodiment. Is a schematic diagram for explaining a coating drying apparatus used to manufacture the battery-. It is a conceptual diagram for explaining a coating liquid supply device for applying a multi-layer paste. It is a schematic diagram for explaining a winding apparatus used to manufacture the battery-. It is a conceptual diagram (the 1) for demonstrating another cooling method of the paste layer which concerns on 1st Embodiment. It is a conceptual diagram (the 2) for demonstrating another cooling method of the paste layer which concerns on 1st Embodiment. It is a schematic block diagram for demonstrating the coating drying apparatus used in manufacturing the battery which concerns on 2nd Embodiment. It is a conceptual diagram for demonstrating the drying method in the coating drying apparatus used in manufacturing the battery which concerns on 3rd Embodiment. It is a perspective view for demonstrating the drying method in the Example which concerns on this invention. It is sectional drawing for demonstrating the cross section of the negative electrode plate in the Example which concerns on this invention. It is sectional drawing for demonstrating the cross section of the negative electrode plate in the comparative example which concerns on this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. The present embodiment embodies the present invention regarding a lithium ion secondary battery, a manufacturing method thereof, and an electrode plate manufacturing apparatus.

(First embodiment)
1. Lithium ion secondary battery The battery according to the present embodiment is a cylindrical lithium ion secondary battery. FIG. 1 shows a cross-sectional view of the battery 100 of this embodiment. As shown in FIG. 1, the battery 100 is sealed by a battery case including a battery container 101 and a lid 102. The battery 100 includes a wound electrode body 200, a positive current collector 110, and a negative current collector 120. In addition, an electrolytic solution is injected into the battery container 101.

  The wound electrode body 200 repeatedly charges and discharges in the electrolytic solution and directly contributes to power generation. The positive electrode current collector plate 110 is a positive electrode current collector connected to a positive electrode core material of a wound electrode body 200 described later. The material is aluminum. The negative electrode current collector plate 120 is a negative electrode current collector connected to a negative electrode core material of a wound electrode body 200 described later. Its material is copper. FIG. 2 shows a perspective view of the wound electrode body 200 in which the positive electrode current collector plate 110 and the negative electrode current collector plate 120 are connected from FIG.

The electrolyte injected into the battery container 101 is obtained by dissolving an electrolyte in an organic solvent. Examples of organic solvents include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), ester solvents such as γ-butylactone (γ-BL), di- An organic solvent containing an ether solvent such as ethoxyethane (DEE) can be used. As the electrolyte salt, lithium salts such as lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), and lithium hexafluorophosphate (LiPF ₆ ) can be used.

  FIG. 3 is a development view showing a wound structure of the wound electrode body 200. As shown in FIG. 3, the wound electrode body 200 is wound in a state in which a positive electrode plate P, a separator S, a negative electrode plate N, and a separator T are stacked in this order from the inside. Here, the separator S and the separator T are insulating members made of the same material. For the understanding of the above winding order, only the codes are distinguished as S and T.

  As shown in FIG. 3, the positive electrode plate P has a positive electrode coating portion P1 and a positive electrode non-coating portion P2. The positive electrode coating part P1 is a place where a positive electrode active material or the like is applied to the positive electrode core material. The positive electrode non-coating portion P2 is a portion where a positive electrode active material or the like is not applied to the positive electrode core material. Therefore, the thickness of the positive electrode coating part P1 is thicker than the thickness of the positive electrode non-coating part P2.

  The negative electrode plate N includes a negative electrode coating portion N1 and a negative electrode non-coating portion N2. The negative electrode coating portion N1 is a portion where a negative electrode active material or the like is applied to the negative electrode core material. The negative electrode non-coating portion N2 is a portion where a negative electrode active material or the like is not applied to the negative electrode core material. Therefore, the thickness of the negative electrode coating part N1 is thicker than the thickness of the negative electrode non-coating part N2.

  An arrow A in FIG. 3 indicates the width direction (vertical direction in FIG. 1) of the positive electrode plate P, the negative electrode plate N, and the separators S and T. An arrow B in FIG. 3 indicates the longitudinal direction of the positive electrode plate P, the negative electrode plate N, and the separators S and T (the circumferential direction of the wound electrode body 200 in FIG. 1). The coating width in the width direction of the positive electrode coating portion P1 is slightly narrower than the coating width in the width direction of the negative electrode coating portion N1. This is because when the concentration of lithium ions in the electrolytic solution is high, the negative electrode active material occludes lithium ions to suppress an increase in the concentration. If the concentration of lithium ions in the electrolyte increases too much, lithium may precipitate in a dendritic form. When such precipitation occurs, the battery performance decreases.

2. FIG. 4 is a perspective sectional view of the positive electrode plate P. The direction indicated by arrow A in FIG. 4 is the same as the direction indicated by arrow A in FIG. That is, it is the width direction of the positive electrode plate P. The direction indicated by arrow B in FIG. 4 is the same as the direction indicated by arrow B in FIG. That is, it is the longitudinal direction of the positive electrode plate P.

  As shown in FIG. 4, the positive electrode plate P is obtained by forming a positive electrode mixture layer PA on a part of both surfaces of a strip-like positive electrode core material PB. On the left side in FIG. 4, a positive electrode non-coated portion P2 of the positive electrode plate P protrudes in the width direction. The positive electrode non-coated portion P2 is formed in a strip shape. The positive electrode uncoated portion P2 is a region where the positive electrode mixture is not applied to both surfaces of the positive electrode core material PB. Therefore, in the positive electrode non-coating portion P2, the positive electrode core material PB is still exposed. On the other hand, on the right side in FIG. 4, there is no protrusion corresponding to the positive electrode non-coated portion P2. In the positive electrode coating part P1, the positive electrode mixture layer PA is formed with a uniform thickness on both surfaces of the positive electrode core material PB.

The positive electrode mixture layer PA is a layer formed by applying a mixture containing a positive electrode active material capable of occluding and releasing lithium ions to an aluminum foil that is the positive electrode core material PB. As the positive electrode active material, lithium composite oxides such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and lithium cobaltate (LiCoO ₂ ) are used. In addition, the composite material includes a binder such as polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), and polyvinylidene fluoride (PVDF), and a thickener such as carboxymethyl cellulose (CMC).

  FIG. 5 is a perspective sectional view of the negative electrode plate N. FIG. The direction indicated by arrow A in FIG. 5 is the same as the direction indicated by arrow A in FIG. That is, it is the width direction of the negative electrode plate N. The direction indicated by the arrow B in FIG. 5 is the same as the direction indicated by the arrow B in FIG. That is, it is the longitudinal direction of the negative electrode plate N.

  As shown in FIG. 5, the negative electrode plate N is obtained by forming a negative electrode mixture layer NA1 and a negative electrode mixture layer NA2 on a part of both surfaces of a strip-like negative electrode core material NB. The negative electrode mixture layer NA1 is formed on both sides of the negative electrode core material NB that is a base material. The negative electrode mixture layer NA2 is formed outside the negative electrode mixture layer NA1, that is, on the surface layer side. Therefore, in the negative electrode plate N, the negative electrode mixture layer NA2, the negative electrode mixture layer NA1, the negative electrode core material NB, the negative electrode mixture layer NA1, and the negative electrode mixture layer NA2 are arranged in this order from the upper side in the drawing.

  On the right side in FIG. 5, the negative electrode non-coated portion N2 of the negative electrode plate N protrudes in the width direction. The negative electrode non-coated portion N2 is formed in a strip shape. The negative electrode non-coated portion N2 is a region where the negative electrode mixture is not applied to both surfaces of the negative electrode core material NB. Therefore, in the negative electrode non-coating portion N2, the negative electrode core material NB is still exposed. On the other hand, there is no protrusion corresponding to the negative electrode non-coated portion N2 on the left side in FIG. In the negative electrode coating portion N1, the negative electrode mixture layer NA1 and the negative electrode mixture layer NA2 are formed with a uniform thickness on both surfaces of the negative electrode core material NB.

  The negative electrode mixture layer NA1 is a layer formed by applying a mixture containing a negative electrode active material capable of occluding and releasing lithium ions to a copper foil as the negative electrode core material NB. As the negative electrode active material, carbon-based materials such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, and graphite are used. The composite material contains a binder such as polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), and polyvinylidene fluoride (PVDF), and a thickener such as carboxymethyl cellulose (CMC).

  The negative electrode mixture layer NA2 is a layer formed by applying a mixture containing a heat-resistant filler. Examples of the heat-resistant filler include alumina, magnesia, silica, titania and the like (insulating metal oxides thereof). Further, the same binder as that used for the negative electrode mixture layer NA2 can be used.

3. Method for Drying Paste Layer A method for drying a plurality of paste layers according to the method for manufacturing the battery 100 of the present invention will be described. In this embodiment, a plurality of paste layers are collectively dried by one drying. FIG. 6 is a conceptual diagram showing a method for drying a plurality of paste layers according to the present invention. The drying of the paste layer when forming the negative electrode mixture layers NA1 and NA2 will be described.

  In this embodiment, as shown in FIG. 6, a hot air nozzle 1301 and a cooling roller 1302 are used for drying the paste layer. Here, the hot air nozzle 1301 is for blowing the hot air H to the negative electrode paste layer NA20. The cooling roller 1302 is for conveying the negative electrode core material NB while supporting it. Moreover, it is a cooling device which also plays the role which cools negative electrode core material NB with the conveyance. The cooling roller 1302 is cooled by cooling water.

  The temperature of the hot air H ejected from the hot air nozzle 1301 is set to 70 ° C., for example. Then, the temperature of the hot air H sprayed on the negative electrode paste layer NA20 is approximately 70 ° C. The temperature of the atmosphere above the negative electrode paste layer NA20 is also about 70 ° C.

  On the other hand, the temperature of the cooling roller 1302 is set to 20 ° C., for example. The temperature of the negative electrode core material NB passing through the cooling roller 1302 is approximately 20 ° C. The temperature of the atmosphere below the negative electrode core material NB and around the cooling roller 1302 is also about 20 ° C.

  Therefore, the temperature difference between the temperature of the negative electrode core material NB and the temperature of the negative electrode paste layer NA20 is approximately 50 ° C. In addition, the temperature difference between the temperature of the atmosphere above the paste layer NA20 and the temperature of the atmosphere below the negative electrode core NB and around the cooling roller 1302 is also about 50 ° C. In this way, the outermost paste layer is heated from the outermost paste layer side, and the opposite surface of the outermost layer is cooled from the opposite side.

  Immediately after the paste is applied, that is, before drying, as shown in FIG. 6, the negative electrode paste layer NA10 and the negative electrode paste layer NA20 are arranged in this order on the negative electrode core material NB. The negative electrode paste layer NA10 is a paste layer containing a negative electrode active material. The negative electrode paste layer NA10 is an undried layer and becomes a negative electrode mixture layer NA1 after drying. The negative electrode paste layer NA20 is a paste layer containing a heat-resistant filler. The negative electrode paste layer NA20 is an undried layer, and becomes a negative electrode mixture layer NA2 after drying. That is, the negative electrode paste layer NA20 is a layer coated on the negative electrode paste layer NA10 without drying it. The solvent of the negative electrode paste layer NA10 and the negative electrode paste layer NA20 is both water. Therefore, the boiling point of water, which is a volatile solvent, of the negative electrode paste layer NA10 and the negative electrode paste layer NA20 is the same.

  In FIG. 6, the negative electrode core material NB is supported by the cooling roller 1302. Therefore, the negative electrode core material NB that is in contact with the cooling roller 1302 is cooled by the cooling roller 1302. This is because the cooling roller 1302 having a lower temperature has a sufficiently larger heat capacity than the negative electrode core material NB.

  In FIG. 6, the negative electrode core material NB, the negative electrode paste layer NA10, and the negative electrode paste layer NA20 are heated from above in the figure by hot air H blown from the hot air nozzle 1301. Of these, the negative electrode paste layer NA20 is best heated. This is because the negative electrode paste layer NA20, the negative electrode paste layer NA10, and the negative electrode core material NB are arranged in this order from the top in the drawing.

  In this drying step, the negative electrode paste layer NA20 is heated by the hot air H blown from the hot air nozzle 1301, and the negative electrode paste layer NA10 is deprived of heat. In the negative electrode paste layer NA10, heat is taken away from the negative electrode paste layer NA20 and heat is taken away from the negative electrode core material NB. Therefore, the temperature is higher in the order of the negative electrode paste layer NA20, the negative electrode paste layer NA10, and the negative electrode core material NB. That is, the temperature closer to the outermost layer of the undried paste layer is higher. Conversely, the temperature of the undried paste layer that is farther from the outermost layer is lower. Therefore, water mainly evaporates from the negative electrode paste layer NA20.

  Therefore, the negative electrode paste layer NA20 is dried faster than the negative electrode paste layer NA10. That is, the drying speed of the upper layer negative electrode paste layer NA20 is higher than the drying speed of the lower layer negative electrode paste layer NA10. Here, the drying speed is the number of molecules of the solvent that volatilizes from the layer per unit time. For gases, if the temperature and pressure are the same, the volume is almost proportional to the number of molecules. Further, in this embodiment, since the solvent of the negative electrode paste layer NA10 and the negative electrode paste layer NA20 is both water, the drying rate in this embodiment is proportional to the weight of water evaporated per unit time.

  Therefore, in the drying process of the multilayer paste layer according to the battery manufacturing method of the present embodiment, the following drying process is followed. That is, first, the temperature of the negative electrode paste layer NA20 rises. At this time, the temperature of the negative electrode paste layer NA10 does not rise so much. This is because the cooling roller 1302 cools the negative electrode core material NB. Therefore, the negative electrode paste layer NA20 starts to dry. If this drying is continued, the moisture in the negative electrode paste layer NA20 is almost evaporated. That is, the negative electrode paste layer NA20 is almost dried.

  At this time, the negative electrode paste layer NA10 is slightly dry compared to the initial state, but still has a sufficient amount of moisture. Since the heat of vaporization by the negative electrode paste layer NA20 is reduced, the temperature of the negative electrode paste layer NA10 becomes a temperature close to 100 ° C. immediately after the negative electrode paste layer NA20 is dried. Then, the negative electrode paste layer NA10 is dried. Here, when moisture evaporates from the negative electrode paste layer NA10, the negative electrode paste layer NA20 hardly becomes an obstacle. This is because the negative electrode paste layer NA20 has fine holes that allow water vapor to pass therethrough. When the drying is continued, the negative electrode paste layer NA10 is almost completely dried.

4). Method for Manufacturing Secondary Battery A method for manufacturing the battery 100 of this embodiment will be described. The manufacturing method of the battery 100 of this embodiment is characterized by the electrode plate coating process and the drying process. Therefore, it demonstrates centering on a coating process and a drying process.

  The schematic block diagram of the coating drying apparatus 1000 of this form is shown in FIG. The coating and drying apparatus 1000 is an electrode plate manufacturing apparatus for creating an electrode plate. As shown in FIG. 7, the coating / drying apparatus 1000 includes an unwinding unit 1100, a coating unit 1200, a drying furnace 1300, and a winding unit 1400. The unwinding unit 1100 has a unwinding shaft 1101. The unwinding shaft 1101 is for unwinding the electrode core material. Therefore, the unwinding shaft 1101 can be rotated.

  The coating unit 1200 includes a coating liquid supply unit 1210 and a backup roller 1220. The coating liquid supply unit 1210 is a coating liquid supply apparatus for applying a multilayer coating liquid to the electrode core material. The backup roller 1220 conveys the electrode core material and supports the electrode core material when the coating liquid supply unit 1210 applies the electrode core material.

  As shown in FIG. 8, the coating liquid supply unit 1210 includes a first coating liquid supply port 1211, a second coating liquid supply port 1212, a first coating liquid holding unit 1213, and a second coating liquid holding unit 1214. Have. The 1st coating liquid supply port 1211 is for coating the coating liquid which forms negative electrode paste layer NA10 on negative electrode core material NB. The 1st coating liquid holding | maintenance part 1213 is a pool part for hold | maintaining the coating liquid. The second coating liquid supply port 1212 is for coating a coating liquid for forming the negative electrode paste layer NA20 on the negative electrode paste layer NA10. The second coating liquid holding part 1214 is a pool part for holding the coating liquid. In addition, when coating is performed on the positive electrode core material PB, the coating liquid may be supplied from one of the first coating liquid supply port 1211 or the second coating liquid supply port 1212. In that case, it is sufficient not to supply the coating liquid to the coating liquid supply port that is not used. Alternatively, a normal coating solution supply apparatus having only one coating solution supply port can be used.

  The drying furnace 1300 is for drying all of one or more paste layers at a time. The drying furnace 1300 includes a hot air nozzle 1301 and a cooling roller 1302 as shown in FIG. The hot air nozzle 1301 is for heating and drying the coating layer. The hot air nozzle 1301 is arranged above the electrode core conveyance path so that the hot air H is ejected toward the conveyance path.

  The cooling roller 1302 is a roller for supporting and transporting the electrode roller in contact with the electrode core material. And it is a cooling device for contacting an electrode core material and cooling an electrode core material in the meantime. The cooling roller 1302 is arranged below the electrode core conveyance path so as to cool toward the conveyance path. When the back surface of the electrode core material that has already been coated / dried is coated / dried, the dried negative electrode mixture layer NA2, which is the lowermost layer in that case, contacts the cooling roller 1302 for cooling. Will be.

  The winding unit 1400 has a winding shaft 1401. The winding shaft 1401 is for winding up the electrode plate from which the coating layer has been dried. The winding shaft 1401 is connected to power such as a motor, and can rotate at a constant rotational speed.

  Accordingly, the electrode core material set on the unwinding shaft 1101 is conveyed to the coating unit 1200 in the direction of arrow C in FIG. Thereafter, the coated paste layer is dried while the electrode core material is conveyed in the drying furnace 1300 in the direction of arrow D in FIG. Thereafter, the electrode core material is wound around the winding shaft 1401 in the direction of arrow E in FIG.

4-1. Production of positive electrode plate The positive electrode plate P is produced by the coating / drying apparatus 1000. The coating liquid supplied from the coating liquid supply unit 1210 is for the positive electrode. Here, the coating process will be described. First, the positive electrode core material PB is sent out from the unwinding shaft 1101. Next, the positive electrode coating liquid is applied to the positive electrode core PB with a predetermined width and thickness by the coating liquid supply unit 1210. Thereby, the paste layer of the positive electrode is applied on the positive electrode core material PB. Next, the drying process will be described. In the drying process, the coated positive electrode core material PB is conveyed into the drying furnace 1300. Inside the drying furnace 1300, the positive electrode paste layer is dried by hot air H blown from the hot air nozzle 1301. Then, the positive electrode plate P from which the positive electrode paste layer is dried is wound around the winding shaft 1401.

  The coating / drying apparatus 1000 shown in FIG. 7 is an apparatus that coats and dries only one side of the electrode core material. Therefore, in order to apply both surfaces, after forming the positive electrode mixture layer PA on one surface, the positive electrode mixture layer PA may be formed on the opposite surface. Therefore, the positive electrode core material PB is passed through the coating / drying apparatus 1000 twice. However, if a coating / drying apparatus that coats and dries both sides instead of the coating / drying apparatus 1000 of FIG. 7 is used, the number of times of passing the positive electrode core material PB through the coating / drying apparatus may be one. The double-sided coating / drying apparatus includes a coating liquid supply apparatus that coats the surface opposite to the coating surface downstream of the drying furnace 1300 in FIG. 7 and a drying furnace downstream thereof. Similarly, the negative electrode plate N can be coated on both sides.

4-2. Production of negative electrode plate The negative electrode plate N is also produced by the coating / drying apparatus 1000. However, the coating liquid supplied from the coating liquid supply unit 1210 is for the negative electrode. Here, the coating process will be described. First, the negative electrode core material NB is unwound from the unwinding part 1100 of the coating drying apparatus 1000. Then, the negative electrode core material NB is conveyed to the coating unit 1200. In the coating unit 1200, the negative electrode paste layer NA10 is coated on the negative electrode core material NB and the negative electrode paste layer NA20 is coated on the negative electrode paste layer NA10 by the coating liquid supply unit 1210 shown in FIG. Subsequently, the negative electrode core material NB coated with the coating liquid is conveyed into the drying furnace 1300.

  Next, the drying process will be described. Inside the drying furnace 1300, the arrangement is as shown in FIG. In the drying furnace 1300, as described above, the negative electrode paste layer NA20 is dried before the negative electrode paste layer NA10. This is because the drying rate of the negative electrode paste layer NA20 is faster than the drying rate of the negative electrode paste layer NA10. After the negative electrode paste layers NA10 and NA20 are dried, the electrode core material NB is wound around the winding shaft 1401. Thus, in this embodiment, two or more paste layers are applied without drying each time, and the two or more paste layers are collectively dried. It should be noted that the order in which the positive electrode plate P and the negative electrode plate N are created may be first.

4-3. Next, the separators S and T are wound on the positive electrode plate P and the negative electrode plate N, which have already been dried, using the winding device 2000 shown in FIG. The winding device 2000 includes a positive electrode plate supply unit 2001, a negative electrode plate supply unit 2002, separator supply units 2003 and 2004, and a winding shaft 2005. Here, as shown in FIG. 3, the positive electrode plate P, the separator S, the negative electrode plate N, and the separator T are stacked and wound in order from the inside. The wound electrode body 200 is created by rotating the wound shaft 2005 in the direction of arrow F in FIG.

4-4. Battery Assembly Step Subsequently, the wound electrode body 200 is inserted into the battery container 101. Then, an electrolytic solution is injected into the battery container 101 and sealed. Thereby, the battery 100 is assembled. After this, it is advisable to perform processes such as conditioning and aging, and various inspection processes.

  The battery manufacturing method of the present embodiment uses a negative electrode plate N in which a negative electrode mixture layer NA1 and a negative electrode mixture layer NA2 are formed in this order on a negative electrode core material NB. In producing the negative electrode plate N, the negative electrode paste layer NA10 and the negative electrode paste layer NA20 are applied to the negative electrode core material NB without being dried each time, and then dried together. In that case, it is made to dry from negative electrode paste layer NA20 far from a base material. This is because, even if convection or the like occurs in the negative electrode paste layer NA10, there is no possibility that the coating liquids of the two are mixed at the boundary surface between the negative electrode paste layer NA20 and the negative electrode paste layer NA10.

5. Modified example 5-1. Here, a modification of the present embodiment will be described. In this embodiment, as shown in FIGS. 6 and 7, the cooling roller 1302 is disposed below the electrode core material NB inside the drying furnace 1300. However, other than the cooling roller 1302 may be used. For example, as shown in FIG. 10, an air nozzle 1303 may be provided below the position through which the electrode core material passes. This is because the electrode core material can be floated by the air nozzle 1303 and the electrode core material can be cooled by the cold air R ejected from the air nozzle 1303.

  Here, the cold air R is air having a temperature lower than that of the hot air H. Therefore, air having a temperature slightly higher than room temperature may be used. Also, air at the same level as room temperature may be used. Further, it may be cooled air. However, the greater the temperature difference between hot air H and cold air R, the greater the effect of the present invention.

  Moreover, as shown in FIG. 11, it is good also as arrange | positioning a surface plate on the lower side of an electrode core material. This is because, if the thickness of the surface plate is sufficient, the heat capacity is large, so that the electrode core material can be sufficiently cooled. The electrode core material is slid and conveyed with respect to the surface plate.

5-2. Heating in the drying furnace Here, another modification will be described. In this embodiment, the hot air nozzle 1301 is used to dry the paste applied to the electrode core material. However, other heating devices may be used. That is, instead of the hot air nozzle 1301, an IR heater or other heater may be used. However, induction heaters cannot be used. It is because it will heat from the electrode core material side instead of the paste side.

5-3. Others The cooling roller 1302 may be a normal roller. In this case, the heating is performed only from the negative electrode paste layer NA20 side of the outermost layer, and there is no change in temperature difference between the negative electrode paste layer NA20 and the negative electrode paste layer NA10.

  Further, heating may be performed weaker than the outermost layer side from the opposite side of the negative electrode paste layer NA20 which is the outermost layer. This is because the temperature difference between the negative electrode paste layer NA20 and the negative electrode paste layer NA10 is not changed. However, in that case, the effect of the present invention is not so great.

6). Summary As described above in detail, the method for manufacturing the battery 100 according to the present embodiment applies a plurality of paste layers to the electrode core and simultaneously dries the plurality of coating layers. . At that time, it is dried not from the base material side but from the paste layer on the side close to the surface layer. This is to prevent the upper and lower paste layers from mixing even if convection occurs in the lower paste layer. Thereby, the manufacturing method of the battery 100 which can dry several paste layers at once is implement | achieved.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, an electrode body used for a battery is not limited to a wound electrode body. Therefore, the present invention can be applied even to a battery having flat electrode bodies. Any secondary battery using stacked electrode bodies stacked and stacked can be applied. The present invention can be applied not only to a cylindrical battery but also to a square battery.

  In addition, the positive electrode mixture layer PA and the negative electrode mixture layers NA1 and NA2 are formed on both sides of the positive electrode core material PB and the negative electrode core material NB, respectively. However, the composite material layer may be formed on only one side. Further, two or more composite material layers may be formed on the positive electrode plate. In that case, the composite material layer formed on the negative electrode plate may be a single layer. The present invention can be applied as long as at least one of the positive electrode plate and the negative electrode plate has two or more composite layers. Then, when forming only one layer of the composite material layer, the coating drying apparatus 1000 of the present embodiment may be used, or a conventional coating drying apparatus that does not have a cooling device such as the cooling roller 1302. May be used. In this embodiment, as shown in FIG. 8, a coating liquid supply unit 1210 that simultaneously coats two layers is used. However, two layers may be applied to the core material by installing coating liquid supply units that apply only one layer at two locations and coating each layer independently.

(Second Embodiment)
A second embodiment will be described. In the battery manufacturing method according to this embodiment, the drying furnace is divided into a plurality of zones, and the electrode core material coated with the paste is passed through the plurality of drying zones to be dried. The other points are the same as in the first embodiment. Therefore, the drying process will be mainly described.

  In this embodiment, the drying furnace 3300 is divided into zone J, zone K, and zone L, as shown in FIG. And each has different drying conditions. In FIG. 12, the electrode core material is conveyed in the direction of arrow I. Accordingly, after the electrode core material is applied, it is transported in the order of zone J, zone K, and zone L.

  As shown in FIG. 12, in the zone J, a hot air nozzle 3301 is arranged in the upper part in FIG. 12, and a cooling roller 3302 is arranged in the lower part in FIG. The temperature of the hot air H ejected from the hot air nozzle 3301 is 110 ° C. The temperature of the cooling roller 3302 is 20 ° C.

  In the zone K, the hot air nozzle 3303 is arranged in the upper part in FIG. 12, and the blower nozzle 3304 is arranged in the lower part in FIG. The temperature of the hot air H ejected from the hot air nozzle 3303 is 130 ° C. The temperature of the cold air R ejected from the blower nozzle 3304 is 30 ° C.

  In the zone L, the hot air nozzle 3305 is arranged in the upper part in FIG. 12, and the hot air nozzle 3306 is arranged in the lower part in FIG. The temperature of the hot air H ejected from the hot air nozzle 3305 is 130 ° C. The temperature of the hot air H ejected from the hot air nozzle 3306 is 130 ° C.

  Therefore, in the drying process of the paste layer using the drying furnace 3300, the difference between the degree of heating from the outermost layer side and the degree of heating from the opposite side is larger in the initial stage of drying. On the other hand, the difference between the degree of heating from the outermost layer side and the degree of heating from the opposite side becomes smaller in the later stage of drying.

  Here, the drying process of the negative electrode plate N of this embodiment will be described. The other steps are the same as those in the first embodiment, and will be omitted. The negative electrode core material NB coated with the negative electrode paste layer NA10 and the negative electrode paste layer NA20 is first conveyed to the zone J. In zone J, the negative electrode paste layer NA20 is dried. At this time, the negative electrode paste layer NA10 is hardly dried. This is because cooling is performed by the cooling roller 3302 via the negative electrode core material NB. Therefore, the temperature of the negative electrode paste layer NA20 is higher than the temperature of the negative electrode paste layer NA10.

  Subsequently, the negative electrode core material NB is conveyed to the zone K. Immediately after being conveyed to the zone K, the negative electrode paste layer NA20 is about half dried. In the middle of the zone K, the negative electrode paste layer NA20 is almost completely dried. Therefore, thereafter, the negative electrode paste layer NA20 is not deprived of the heat of vaporization. Then, the negative electrode paste layer NA10 starts to dry. Even at this stage, the temperature of the negative electrode paste layer NA20 is higher than the temperature of the negative electrode paste layer NA10. This is because the negative electrode paste layer NA20 has almost lost water and has reached a temperature of 100 ° C. or higher, which is the boiling point of water.

  Subsequently, the negative electrode core material NB is conveyed to the zone L. Immediately after being conveyed to the zone L, the negative electrode paste layer NA10 is about half dried. In the zone L, both the negative electrode paste layer NA20 side and the negative electrode core material NB side are heated, so that most of the remaining water in the negative electrode paste layer NA20 and the negative electrode paste layer NA10 is evaporated.

  Thereby, the negative electrode plate N formed with the negative electrode mixture layer NA1 and the negative electrode mixture layer NA2 is produced. Thereafter, a lithium ion secondary battery is manufactured through the same process as in the first embodiment. The method for manufacturing a lithium ion secondary battery according to this embodiment can evaporate moisture from the negative electrode paste layers NA20 and NA10 more reliably than the method for manufacturing a secondary battery according to the first embodiment. This is because the zone L is heated from both sides.

  Even in the case of double-sided coating, there is no problem in drying the negative electrode paste layers NA10 and NA20. This is because the negative electrode mixture layers NA1 and NA2 that have already been dried are merely heated, and there is no loss of thermal energy due to the heat of vaporization.

  As described above in detail, the battery manufacturing method according to the present embodiment applies a plurality of paste layers to the electrode core material and simultaneously dries the plurality of coating layers. At that time, it is dried not from the base material side but from the paste layer on the side close to the surface layer. This is to prevent the upper and lower paste layers from mixing even if convection occurs in the lower paste layer. As a result, a battery manufacturing method capable of drying a plurality of paste layers at a time is realized.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, an electrode body used for a battery is not limited to a wound electrode body. Therefore, the present invention can be applied even to a battery having flat electrode bodies. Any secondary battery using stacked electrode bodies stacked and stacked can be applied. The present invention can be applied not only to a cylindrical battery but also to a square battery.

  In addition, the positive electrode mixture layer PA and the negative electrode mixture layers NA1 and NA2 are formed on both sides of the positive electrode core material PB and the negative electrode core material NB, respectively. However, the composite material layer may be formed on only one side. Further, two or more composite material layers may be formed on the positive electrode plate. In that case, the composite material layer formed on the negative electrode plate may be a single layer. The present invention can be applied as long as at least one of the positive electrode plate and the negative electrode plate has two or more composite layers. In the case of forming a single-layer mixture layer, a coating / drying apparatus having the drying furnace 3300 of this embodiment may be used, or a conventional apparatus that does not have a cooling apparatus such as the cooling roller 3302 may be used. A coating and drying apparatus may be used.

(Third embodiment)
A third embodiment will be described. In the battery manufacturing method according to this embodiment, three or more paste layers are applied on the negative electrode core material NB, and the paste layers are all dried at once. The other steps are the same as those in the first embodiment. Therefore, the process of applying a number of paste layers and the process of drying will be mainly described.

  In this embodiment, a large number of paste layers of three or more layers are formed on the negative electrode core material NB. FIG. 13 is a conceptual diagram showing a case where an M paste layer is formed on the negative electrode core NB. Here, M is an integer of 3 or more. As shown in FIG. 13, the first layer, the second layer,..., The Mth layer are formed from the negative electrode core side. Of these paste layers, the outermost layer is the Mth layer. Moreover, the solvent of these paste layers is all water.

  In the battery manufacturing method of this embodiment, the coating drying apparatus 1000 shown in FIG. 7 may be used in which M coating liquid supply ports are arranged in the coating liquid supply unit. This is because an M paste layer is formed on the negative electrode core NB. In the drying furnace 1300, the furnace length may be designed according to the thickness of the paste layer of the M layer. Further, the set temperature in the furnace and the set temperature of the hot air H may be changed.

  Here, a method for manufacturing the battery of this embodiment will be described. Similarly to the first embodiment, the negative electrode core material NB is conveyed to the coating unit 1200. In the coating unit 1200, M paste layers are formed on the negative electrode core NB by M coating liquid supply ports.

  Subsequently, as shown in FIG. 13, the paste layer of the M layer is heated from the side of the Mth layer which is the outermost layer. On the other hand, the negative electrode core material NB is cooled by the cooling roller 1302. Therefore, the Mth layer receives the hot air H blown from the hot air nozzle 1301. The Mth layer is heated by hot air H, and the (M-1) th layer is deprived of heat. In the (M-1) th layer, heat is taken from the Mth layer and heat is taken away by the (M-2) th layer.

  In the second layer, heat is taken away from the third layer, and heat is taken away in the first layer. In the first layer, heat is taken away from the second layer, and heat is taken away by the negative electrode core material NB. The negative electrode core material NB takes heat from the first layer and is cooled by the cooling roller 1302.

Thus, the relationship between the temperatures of the layers is as follows.
Temperature of Mth layer ≧ Temperature of (M-1) layer ≧ Temperature of (M-2) layer
…… ≧ Temperature of the second layer ≧ Temperature of the first layer, that is, the higher the temperature of the undried paste layer, the higher the temperature. Conversely, the lower layer of the undried paste layer tends to have a lower temperature.

Therefore, when different types of volatile solvents are used in each layer, the temperature relationship of each layer is as follows.
Temperature of Mth layer> Temperature of (M-1) layer> Temperature of (M-2) layer
.... temperature of the second layer> temperature of the first layer, that is, the temperature of the upper layer of the undried paste layer is higher. Conversely, the lower layer of the undried paste layer has a lower temperature.

  In this way, heating from the outermost layer side is the same as in the first embodiment. Therefore, the order of drying the M layer paste layers is as follows. That is, the order is the Mth layer, the (M−1) th layer,..., The second layer, and the first layer.

  The drying speed is as follows. That is, the drying speed is faster in the order of the Mth layer, the (M-1) th layer, ..., the second layer, and the first layer.

  Thereby, the negative electrode plate N in which the negative electrode composite material layer of M layers was formed is produced. Thereafter, a lithium ion secondary battery is manufactured through the same process as in the first embodiment. In the manufacturing method of the lithium ion secondary battery of this embodiment, a secondary battery having an electrode plate having a multilayer paste layer can be manufactured.

  As described above in detail, the method for manufacturing a battery according to the present embodiment applies three or more paste layers to the electrode core material and simultaneously dries three or more coating layers. It is. At that time, it is dried not from the base material side but from the paste layer on the side close to the surface layer. This is to prevent the upper and lower paste layers from mixing even if convection occurs in the lower paste layer. Thereby, the manufacturing method of the battery which can dry three or more paste layers at once is implement | achieved.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, an electrode body used for a battery is not limited to a wound electrode body. Therefore, the present invention can be applied even to a battery having flat electrode bodies. Any secondary battery using stacked electrode bodies stacked and stacked can be applied. The present invention can be applied not only to a cylindrical battery but also to a square battery.

  In addition, the positive electrode mixture layer PA, the negative electrode mixture layers NA1, NA2, and the like are formed on both sides of the positive electrode core material PB and the negative electrode core material NB, respectively. However, the composite material layer may be formed on only one side. Moreover, the composite material layer of 3 or more layers may be formed in the positive electrode plate. In that case, the composite material layer formed on the negative electrode plate may be a single layer. The present invention can be applied as long as three or more composite layers are formed on at least one of the positive electrode plate and the negative electrode plate. And when forming only the single-material mixture layer, you may use the coating drying apparatus 1000 which concerns on this invention, and the conventional coating drying apparatus which does not have cooling devices, such as the cooling roller 1302, is used. It may be used.

(Fourth embodiment)
A fourth embodiment will be described. The difference between this embodiment and the first embodiment is the volatilization temperature of the solvent used for the negative electrode paste layer NA10 and the negative electrode paste layer NA20. Other than that, it is almost the same as the first embodiment. Therefore, the differences will be mainly described.

  In the manufacturing method of this embodiment, N-methyl-2-pyrrolidone (NMP, hereinafter referred to as NMP) is used as the volatile solvent of the negative electrode paste layer NA10 shown in FIG. The boiling point of NMP at atmospheric pressure is 202 ° C. The solvent of the negative electrode paste layer NA20 is water. The boiling point at atmospheric pressure is of course 100 ° C.

  That is, in this embodiment, the boiling point of the solvent of the negative electrode paste layer NA20 is lower than the boiling point of the solvent of the negative electrode paste layer NA10. Therefore, among these two paste layers, the negative electrode paste layer NA20 is first dried and then the negative electrode paste layer NA10 is dried. This drying order is the same as that in the first embodiment. That is, the drying rate of the negative electrode paste layer NA20 is faster than the drying rate of the negative electrode paste layer NA10.

  In this embodiment, the temperature of the hot air H ejected from the hot air nozzle 1301 is set to about 250 ° C. This is because the paste layer is dried at a temperature higher than the boiling point of NMP. That is, the temperature of the hot air H set by the drying of this embodiment is higher than that of the first embodiment.

  Next, the drying process will be described. The negative electrode core material NB coated with the two paste layers is conveyed into the drying furnace 1300. First, the temperature of the negative electrode paste layer NA20 that is the outermost layer rises. On the other hand, the temperature of the negative electrode paste layer NA10 does not rise so much. This is because the cooling roller 1302 cools the negative electrode core material NB. That is, the temperature of the negative electrode paste layer NA20 is higher than the temperature of the negative electrode paste layer NA10. Here, since the temperature of the negative electrode paste layer NA20 is less than 100 ° C., the negative electrode paste layer NA10 is hardly dried.

  If the drying is continued as it is, the negative electrode paste layer NA20 is almost dried. Then, the temperature of the negative electrode paste layer NA20 rises above 100 ° C., which is the boiling point of water. Eventually, it exceeds 202 ° C., the boiling point of NMP. Subsequently, the temperature of the negative electrode paste layer NA10 reaches 202 ° C., which is the boiling point of NMP. Near that temperature, most of the NMP volatilizes. Even here, the temperature of the negative electrode paste layer NA20 is higher than the temperature of the negative electrode paste layer NA10.

  Thus, even during the drying, the temperature of the undried paste layer closer to the outermost layer is higher. Conversely, the temperature of the undried paste layer that is farther from the outermost layer is lower. If this drying is continued, the negative electrode paste layer NA10 will eventually be dried.

  Thereby, the negative electrode plate N formed with the negative electrode mixture layer NA1 and the negative electrode mixture layer NA2 is produced. Thereafter, a lithium ion secondary battery is manufactured through the same process as in the first embodiment.

  The battery manufactured by the battery manufacturing method of the present embodiment is substantially the same as the battery 100 of the first embodiment. However, in general, the solvent is not completely removed from the composite layer of the positive electrode plate and the negative electrode plate. In addition, a small amount of solvent remains in the mixture layer even after the battery is formed. Therefore, it is possible to identify the type of solvent used to form the composite layer by disassembling the battery and performing an appropriate analysis on the composite layer.

  As described in detail above, this embodiment has the characteristics that 1) drying from the outermost layer side, and 2) the solvent in the upper layer has a lower volatilization temperature. Therefore, the present embodiment can suppress the mixing of the upper paste layer and the lower paste layer due to the lower layer convection, compared to the first embodiment having only the feature point 1).

  Here, a modification of this embodiment will be described. In this embodiment, the coating / drying apparatus 1000 is used to create the negative electrode plate N. However, the effect of the present invention can be obtained without cooling from the negative electrode core material NB side. Therefore, a conventional coating drying apparatus that does not have the cooling roller 1302 may be used. However, it goes without saying that it is more effective to use the coating / drying apparatus 1000.

  Another modification of this embodiment will be described. In this embodiment, water is used as the solvent for the negative electrode paste layer NA20, and NMP is used as the solvent for the negative electrode paste layer NA10. However, other solvent combinations may be used. For example, methyl ethyl ketone (MEK) can be used as the solvent of the negative electrode paste layer NA20, and water can be used as the solvent of the negative electrode paste layer NA10.

  The boiling point of methyl ethyl ketone is 79.5 ° C. The boiling point of water is 100 ° C. Therefore, the temperature of the volatile solvent of the negative electrode paste layer NA20 is lower than the temperature of the volatile solvent of the negative electrode paste layer NA10.

You may make it form the paste layer of M layer like 2nd Embodiment. In that case, the following relationship holds.
Volatilization temperature of the solvent of the Mth layer ≦ Volatilization temperature of the solvent of the (M-1) th layer Volatilization temperature of the solvent of the (M-1) th layer ≦ Volatilization temperature of the solvent of the (M-2) th layer Volatilization temperature of the solvent ≦ Volatilization temperature of the solvent in the first layer

  As described above in detail, the battery manufacturing method according to the present embodiment applies a plurality of paste layers to the electrode core material and simultaneously dries the plurality of coating layers. At that time, it is dried not from the base material side but from the paste layer on the side close to the surface layer. This is to prevent the upper and lower paste layers from mixing even if convection occurs in the lower paste layer. Thereby, the manufacturing method of the battery which can be dried in one process is realized, without drying the paste layer of several layers at every coating.

  In addition, the battery according to the present embodiment includes a positive electrode plate P, a negative electrode plate N, and a wound electrode body 200 wound with a separator sandwiched therebetween. In the negative electrode plate N, two negative electrode mixture layers NA1 and NA2 are formed on both surfaces of the negative electrode core material NB. Of the two negative electrode mixture layers, the volatilization temperature of the solvent slightly contained in the outermost negative electrode mixture layer NA2 is slightly contained in the negative electrode mixture layer NA1 located therebelow. Below the volatilization temperature of the solvent.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, an electrode body used for a battery is not limited to a wound electrode body. Therefore, the present invention can be applied even to a battery having flat electrode bodies. Any secondary battery using stacked electrode bodies stacked and stacked can be applied. The present invention can be applied not only to a cylindrical battery but also to a square battery.

  In addition, the positive electrode mixture layer PA and the negative electrode mixture layers NA1 and NA2 are formed on both sides of the positive electrode core material PB and the negative electrode core material NB, respectively. However, the composite material layer may be formed on only one side. Further, two or more composite material layers may be formed on the positive electrode plate. In that case, the composite material layer formed on the negative electrode plate may be a single layer. The present invention can be applied as long as at least one of the positive electrode plate and the negative electrode plate has two or more composite layers. And when forming only the single-material mixture layer, you may use the coating drying apparatus 1000 which concerns on this invention, and the conventional coating drying apparatus which does not have cooling devices, such as the cooling roller 1302, is used. It may be used.

  Here, an experiment in which the surface layer drying rate is made faster than the lower layer drying rate will be described. In Example 1, it was dried by the drying method shown in FIG. In Comparative Example 1, the substrate was heated and dried from the negative electrode core material side. Regarding conditions other than the drying conditions shown here, Example 1 and Comparative Example 1 are the same.

  The sample materials used in this experiment are shown below. The negative electrode core material is a copper foil. The lower negative electrode paste layer (corresponding to the negative electrode paste layer NA10 in FIG. 6) is a paste containing the negative electrode active material described in the first embodiment. The upper negative electrode paste layer (corresponding to the negative electrode paste layer NA20 in FIG. 6) is a paste containing the heat-resistant filler described in the first embodiment. The solvent of these pastes is water.

  The drying method in Example 1 will be described with reference to FIG. As shown in FIG. 14, a sample is placed on a surface plate. The material of the surface plate is stainless steel. At this time, it arrange | positions so that the copper foil which is a negative electrode core material may turn down. With this arrangement, the upper negative electrode paste layer becomes the outermost layer. Then, hot air H is applied to the upper negative electrode paste layer by the heat gun 301. The surface plate is large enough. The temperature is sufficiently lower than that of the hot air H.

  Therefore, in the state where hot air H is applied to the upper negative paste layer, the temperature is higher in the order of the upper negative paste layer, the lower negative paste layer, and the surface plate. That is, the drying speed of the upper negative electrode paste layer is faster than the drying speed of the lower negative electrode paste layer.

  The drying method in Comparative Example 1 will be described. In the comparative example 1, it heats from a surface plate. Therefore, during drying, the temperature of the upper negative electrode paste layer is lower than that of the lower negative electrode paste layer. Therefore, the lower negative electrode paste layer is first dried. Then, after the lower negative electrode paste layer is dried, the upper negative electrode paste layer is dried. Therefore, the drying speed of the upper negative electrode paste layer is slower than the drying speed of the lower negative electrode paste layer.

  15 is a cross-sectional view showing a cross section of a sample of the negative electrode plate after drying in Example 1. FIG. In Example 1, the thickness of the lower paste layer is about 100 μm. The thickness of the upper paste layer is about 20 μm.

  16 is a cross-sectional view showing a cross section of a sample of the negative electrode plate after drying in Comparative Example 1. FIG. In Comparative Example 1, the thickness of the lower paste layer is about 100 μm. The thickness of the upper paste layer is about 60 μm.

  When Example 1 and Comparative Example 1 are compared, the lower paste layers are approximately the same at about 100 μm. The upper paste layer in Example 1 is thinner than the upper paste layer in Comparative Example 1. The boundary surface X between the upper paste layer and the lower paste layer in Example 1 is flatter than the boundary surface Y between the upper paste layer and the lower paste layer in Comparative Example 1. That is, there are few irregularities. The unevenness on the boundary surface X is about 1 μm. The unevenness at the boundary surface Y is about 10 μm.

DESCRIPTION OF SYMBOLS 100 ... Battery 110 ... Positive electrode current collecting plate 120 ... Negative electrode current collecting plate 200 ... Winding electrode body 1000 ... Coating drying apparatus 1100 ... Unwinding part 1200 ... Coating part 1210 ... Coating liquid supply part 1211 ... 1st coating liquid supply Port 1212 ... Second coating liquid supply port 1220 ... Backup rollers 1300 and 3300 ... Drying furnaces 1301, 3301, 3303, 3305 and 3306 ... Hot air nozzles 1302 and 3302 ... Cooling rollers 1303 ... Air nozzles 304 ... ... winding device 2001 ... positive electrode plate supply unit 2002 ... negative electrode plate supply unit 2003, 2004 ... separator supply unit 2005 ... winding axis P ... positive electrode plate PA ... positive electrode mixture layer PB ... positive electrode core material P1 ... positive electrode coating unit P2 ... Non-coated positive electrode part N ... Negative electrode plate NA1, NA2 ... Negative electrode mixture layer NA10, NA20 ... Negative electrode paste layer NB ... Negative electrode core material N1 Fukyokunuriko portion N2 ... negative electrode non-coated portion S, T ... separator X, Y ... interface

Claims (10)

A coating process for applying a paste layer to the positive electrode core material or the negative electrode core material;
A drying step of drying the paste layer coated in the coating step to form a positive electrode plate or a negative electrode plate;
An electrode body creation step of creating an electrode body by stacking the positive electrode plate and the negative electrode plate dried in the drying step and a separator for insulating them;
In a method for manufacturing a secondary battery, the battery assembly process includes inserting the electrode body created in the electrode body creation process into a battery container and injecting an electrolyte into the battery container.
In the coating process,
At least one of the positive electrode core material and the negative electrode core material is coated with two or more paste layers without drying each time,
In the drying step,
When drying two or more undried paste layers,
Of the two or more undried paste layers, the closer the outermost paste layer is,
Increase the temperature of the paste layer,
Of the two or more undried paste layers, the paste layer farthest from the outermost layer is
A method for manufacturing a secondary battery, wherein the temperature of the paste layer is lowered. A method of manufacturing a secondary battery according to claim 1,
In at least part of the drying step,
When drying two or more undried paste layers,
A method of manufacturing a secondary battery, comprising heating the outermost paste layer only from the outermost paste layer side in the two or more undried paste layers. A method of manufacturing a secondary battery according to claim 1,
In at least part of the drying step,
When drying two or more undried paste layers,
Heating the outermost paste layer from the front side of the outermost paste layer in two or more undried paste layers,
A method for manufacturing a secondary battery, comprising: heating a surface on the opposite side of the outermost layer from an opposite side of the outermost paste layer in two or more undried paste layers to be weaker than heating from the front side. A method of manufacturing a secondary battery according to claim 1,
In at least part of the drying step,
When drying two or more undried paste layers,
Heating the outermost paste layer from the front side of the outermost paste layer in two or more undried paste layers,
A method of manufacturing a secondary battery, comprising cooling an opposite surface of the outermost layer from an opposite side of the outermost paste layer in two or more undried paste layers. A method for manufacturing a secondary battery according to any one of claims 1 to 4,
In the coating process,
When coating two or more paste layers without drying each time,
As the volatile solvent in the paste layer that is not the outermost layer of the two or more paste layers, a solvent whose boiling point under atmospheric pressure is equal to or higher than the boiling point under atmospheric pressure of the volatile solvent in the paste layer above the paste layer is used. A method for producing a secondary battery. A method of manufacturing a secondary battery according to any one of claims 1 to 5,
In at least part of the drying step,
When drying two or more undried paste layers,
A method for manufacturing a secondary battery, wherein a temperature of an atmosphere located above the paste layer of the outermost layer is higher than a temperature of an atmosphere located below the positive electrode core material or the negative electrode core material. A method of manufacturing a secondary battery according to claim 6,
In at least part of the drying step,
When drying two or more undried paste layers,
A method for producing a secondary battery, characterized in that the temperature of the atmosphere positioned above the outermost paste layer is 50 ° C. higher than the temperature of the atmosphere positioned below the positive electrode core material or the negative electrode core material . A method for manufacturing a secondary battery according to any one of claims 1 to 7,
In the drying step,
The earlier the drying process,
There is a large difference between the degree of heating from the outermost layer side of the undried paste layer and the degree of heating from the opposite side of the outermost layer,
Later in the drying process,
A method for manufacturing a secondary battery, characterized in that a difference between a degree of heating of the undried paste layer from the outermost layer side and a degree of heating from the opposite side of the outermost layer is small. An unwinding portion for unwinding the electrode core material of the electrode plate of the secondary battery ;
A coating part in which two or more paste layers are stacked in an undried state on the electrode core material to form a coating layer;
The coating layer ,
Of the two or more undried paste layers, the closer the paste layer to the outermost layer,
Increase the temperature of the paste layer,
Of the two or more undried paste layers, the farther away from the outermost layer,
While lowering the temperature of the paste layer,
A drying oven for drying;
The coating layer of the electrode plate manufacturing device for a secondary battery, wherein the Turkey of having a take-up portion for winding said electrode core member that is dried. An apparatus for manufacturing an electrode plate for a secondary battery according to claim 9,
In at least part of the drying oven,
A heating device for heating toward the transport path is disposed above the transport path of the coated electrode core material,
An apparatus for manufacturing an electrode plate for a secondary battery, wherein a cooling device for cooling toward the transport path is disposed below the transport path.

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