JP2020087853A - Lithium-ion secondary battery electrode manufacturing apparatus and lithium-ion secondary battery electrode manufacturing method - Google Patents

Abstract

To prevent wrinkles from being formed on a metal foil when an active material layer is pressed.SOLUTION: A lithium-ion secondary battery electrode manufacturing apparatus includes a transport device that transports a metal foil 11, a coating device that coats an active material mixture 42 on the metal foil 11, a drying device, a blower nozzle 91 arranged in the drying device, a control unit that controls an air blow from the blower nozzle 91, and a pressure device. The blower nozzle 91 is arranged so as to face the upstream side in the transport direction of the metal foil 11. The blower nozzle 91 is arranged so as to face both ends 43A and 43B obliquely when viewed from the direction along the surface of the metal foil 11.SELECTED DRAWING: Figure 5

Description

The present invention relates to an apparatus for manufacturing an electrode for a lithium ion secondary battery and a method for manufacturing an electrode for a lithium ion secondary battery.

The lithium ion secondary battery includes positive and negative electrodes. The electrode is obtained by cutting an electrode sheet which is a raw material of the electrode. The electrode sheet includes a coated portion where the strip-shaped metal foil and the active material layer overlap with each other, and an uncoated portion where the strip-shaped metal foil and the active material layer do not overlap with each other. Patent Document 1 describes a manufacturing apparatus for manufacturing an electrode sheet. The electrode sheet is manufactured by providing an active material layer on a strip-shaped metal foil and pressing the active material layer. The manufacturing apparatus described in Patent Document 1 presses the active material layer with a pair of press rolls.

JP, 2016-139582, A

By the way, by being pressed by the press roll, the strip-shaped metal foil of the coated portion is rolled through the active material layer. On the other hand, the uncoated portion where the active material layer is not provided is hardly pressed by the press roll. There is a difference in the lengthwise direction between the strip-shaped metal foil of the coated part and the uncoated part, and wrinkles may occur at the boundary between the uncoated part and the coated part due to this difference. is there. The wrinkles also remain on the electrode obtained from the electrode sheet, which causes the active material layer to peel off from the metal foil.

An object of the present invention is to provide a manufacturing apparatus of an electrode for a lithium ion secondary battery and a manufacturing method of an electrode for a lithium ion secondary battery capable of suppressing wrinkles from being generated on a metal foil when pressure is applied to an active material layer. To provide.

An apparatus for manufacturing an electrode for a lithium-ion secondary battery that solves the above-mentioned problems, a conveying device that conveys a long metal foil, and an active material mixture layer that becomes an active material layer by drying on the metal foil. A coating device for forming, a drying device for drying the active material mixture layer, and a portion located between the active material mixture layer and both edges in the lateral direction of the metal foil as an uncoated portion. Then, by blowing gas toward the end of the active material mixture layer along the uncoated portion, it is possible to form the end portion toward the uncoated portion to be gradually thinned, And, a plurality of air-blowing nozzles arranged in the drying device, and a pressure device for pressurizing the active material layer, each air-blowing nozzle, facing the upstream of the transport direction of the metal foil, and, The metal foil is arranged so as to be oblique to the end when viewed from the direction along the surface of the metal foil.

When manufacturing an electrode for a lithium-ion secondary battery, gas is blown from a blow nozzle provided in the drying device. Since the air blowing nozzle is arranged so as to be obliquely oriented with respect to the end portion of the active material mixture layer, when air is blown from the air blowing nozzle, the end portion of the active material mixture layer flows by wind pressure, It is formed so as to gradually become thinner toward the uncoated portion. Since the active material mixture layer does not dry as much as the upstream of the metal foil in the conveying direction, the blowing nozzle is directed upstream in the conveying direction of the metal foil, and the active material mixture at the end portion is made to flow upstream. The active material mixture layer can be leveled. By drying the active material mixture layer in this state, an active material layer is formed in which the end portion along the uncoated portion gradually becomes thinner toward the uncoated portion. When the active material layer is pressed by the pressing device, the thicker the active material layer is, the larger the force applied to the metal foil is. Therefore, by gradually thinning the end portion of the active material layer toward the uncoated portion, as compared with the case where the entire active material layer including the end portion has a constant thickness, The amount of extension of the portion in contact with the end can be reduced. Therefore, when the active material layer is pressed, it is possible to suppress the generation of wrinkles due to the rolling of the metal foil due to the pressing.

A method for manufacturing an electrode for a lithium-ion secondary battery that solves the above problems, a long metal foil to be transported, a coating step of forming an active material mixture layer to be an active material layer by drying. A drying step of drying the active material mixture layer, and a drying step which is performed at the same time, and a portion located between the active material mixture layer and both edges of the metal foil in the lateral direction is uncoated. Part, the end portion of the active material mixture layer along the uncoated portion is blown to form an end portion toward the uncoated portion to be gradually thinned. An air blowing step and a pressurizing step of pressurizing the active material layer are provided, and in the air blowing step, the end faces the upstream side in the transport direction of the metal foil and when viewed from the direction along the surface of the metal foil. The gas is blown from a blowing nozzle that is arranged so as to be oblique to the portion.

According to this, by gradually thinning the end portion of the active material layer toward the uncoated portion by the blowing step, compared to the case where the entire active material layer including the end portion has a constant thickness, It is possible to reduce the amount of extension of the portion of the metal foil in contact with the end portion of the active material layer during the pressing step. Therefore, when the active material layer is pressed, it is possible to suppress the generation of wrinkles due to the rolling of the metal foil due to the pressing.

According to the present invention, it is possible to suppress the formation of wrinkles in the metal foil when the active material layer is pressed.

The top view of an electrode sheet. FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, showing an electrode sheet. The schematic block diagram which shows the manufacturing apparatus of the electrode for lithium ion secondary batteries. The schematic diagram at the time of seeing the ventilation nozzle arrange|positioned in the drying device from the thickness direction of a metal foil. The schematic diagram at the time of seeing the ventilation nozzle arrange|positioned in the drying device from the longitudinal direction of a metal foil.

Hereinafter, an embodiment of an apparatus for manufacturing an electrode for a lithium ion secondary battery and a method for manufacturing an electrode for a lithium ion secondary battery will be described.
As shown in FIGS. 1 and 2, the electrode sheet 10 has an elongated shape. The electrode sheet 10 includes a coated portion 21 in which an active material layer 12 is provided on a long metal foil 11 and an uncoated portion 22 from which the metal foil 11 is exposed. The electrode sheet 10 is a raw material of the electrode 30. The lithium ion secondary battery is an electrode assembly in which individual electrodes 30 cut out from the electrode sheet 10 are stacked via a separator, and the electrode assembly is housed in a case.

When the electrode sheet 10 is a raw material for a positive electrode of a lithium ion secondary battery, the metal foil 11 is an aluminum foil. When the electrode sheet 10 is a raw material of the negative electrode of the lithium ion secondary battery, the metal foil 11 is a copper foil. The active material layer 12 contains an active material, a conductive agent, and a binder depending on the polarity.

The active material layer 12 is provided over the entire length of the metal foil 11. The active material layer 12 is provided with a constant width in the center of the metal foil 11 in the lateral direction. The uncoated portions 22 are provided on both sides in the lateral direction of the metal foil 11 with the coated portion 21 interposed therebetween. The uncoated portion 22 is provided over the entire length of the metal foil 11 in the longitudinal direction. Both end portions 23 of the active material layer 12 are gradually thinned toward the uncoated portion 22 closest to the both end portions 23. The surfaces of both ends 23 of the active material layer 12 are inclined in an arc shape so as to be recessed in the thickness direction of the active material layer 12.

The electrode sheet 10 including the coated part 21 and the uncoated part 22 can be regarded as an electrode for a lithium ion secondary battery. As can be understood from FIG. 1, the individual electrode 30 cut out from the electrode sheet 10 is also cut out from the electrode sheet 10 with the coated portion 21 and the uncoated portion 22. Therefore, the individual electrode 30 cut out from the electrode sheet 10 can also be regarded as an electrode for a lithium ion secondary battery. That is, the electrode for the lithium ion secondary battery may be any electrode as long as it has the coated portion 21 and the uncoated portion 22, and the electrode sheet 10 before cutting the individual electrode 30 is used for the lithium ion secondary battery. The electrode 30 can be regarded as an electrode of the lithium ion secondary battery, or the individual electrode 30 cut out from the electrode sheet 10 can be regarded as an electrode for a lithium ion secondary battery.

Next, an apparatus for manufacturing an electrode for a lithium ion secondary battery (hereinafter referred to as a manufacturing apparatus) will be described. The manufacturing apparatus of this embodiment is an apparatus for manufacturing the electrode sheet 10. The manufacturing apparatus of the present embodiment may be provided with a cutting device that cuts out the individual electrodes 30 from the electrode sheet 10, so that the manufacturing apparatus may be a device that manufactures the electrodes 30. That is, the manufacturing apparatus may be an apparatus for manufacturing the electrode sheet 10 or an apparatus for manufacturing the individual electrode 30 as the electrode for the lithium ion secondary battery.

As shown in FIGS. 3 and 4, the manufacturing apparatus 41 includes a carrying device 50 for carrying the metal foil 11, a coating device 60 for applying the active material mixture 42 to the metal foil 11, a drying device 80, and a drying device 80. An air blowing nozzle 91 arranged in the device 80, a control unit 92 for controlling the air blowing from the air blowing nozzle 91, and a pressurizing device 81 are provided. The manufacturing apparatus 41 is arranged in, for example, a dry room.

The transport device 50 includes a supply device 51 that supplies the metal foil 11 and a winding device 55 that winds the manufactured electrode sheet 10. The supply device 51 includes a supply reel 52 around which the metal foil 11 is wound, and a first shaft 53 on which the supply reel 52 is installed. The supply reel 52 is rotatably supported by the first shaft 53. The metal foil 11 pulled out from the supply reel 52 is in a state where the longitudinal direction extends in the circumferential direction of the supply reel 52. Although illustration is omitted, in the present embodiment, it is assumed that the metal foil 11 having the active material layer 12 already formed on one of the both surfaces is wound around the supply reel 52.

The winding device 55 includes a winding reel 56 that winds the electrode sheet 10, and a second shaft 57 on which the winding reel 56 is installed. The take-up reel 56 is rotatably supported by the second shaft 57. The electrode sheet 10 is wound around the take-up reel 56 with the longitudinal direction extending in the circumferential direction of the take-up reel 56. The supply reel 52 and the take-up reel 56 rotate by rotating both the first shaft 53 and the second shaft 57, or the second shaft 57 by a drive source such as a motor (not shown). Thereby, the metal foil 11 is conveyed. In the following description, the carrying direction refers to the carrying direction of the metal foil 11.

The coating device 60 is located downstream of the supply device 51 in the transport direction. The coating device 60 includes a die head 62 and a backup roll 61 that is arranged apart from the die head 62. The die head 62 includes a manifold 63 in which the active material mixture 42 is stored, a discharge port 64 of the active material mixture 42, and a slot 65 for discharging the active material mixture 42 from the discharge port 64. The die head 62 is arranged so that the ejection port 64 faces the metal foil 11. The slot 65 connects the manifold 63 and the discharge port 64. The active material mixture 42 is a paste in which an active material, a conductive agent, a binder and a solvent are mixed. The coating device 60 applies the active material mixture 42 to the center of the metal foil 11 in the lateral direction with a constant width. As a result, the active material mixture layer 43, which is a layer of the active material mixture 42, is formed on the metal foil 11. The active material mixture layer 43 becomes the active material layer 12 by drying. Both ends 43A, 43B in the width direction of the active material mixture layer 43 are along the uncoated portion 22 located between the active material mixture layer 43 and both edges E1, E2 in the lateral direction of the metal foil 11. .

The drying device 80 is located downstream of the coating device 60 in the transport direction. The drying device 80 dries the active material mixture layer 43, for example, by raising the atmospheric temperature in the furnace by a heating unit. The active material mixture layer 43 is gradually dried by passing through the drying device 80.

FIG. 4 schematically shows the arrangement position of the blowing nozzle 91. The blowing nozzle 91 is supported by the drying device 80 by a supporting unit (not shown). Gas is supplied to the blower nozzle 91 from a supply source (not shown). The control unit 92 blows gas from the blowing nozzle 91 by controlling the supply source. The gas blown from the blowing nozzle 91 is, for example, dry air.

A plurality of blower nozzles 91 are arranged corresponding to both ends 43A and 43B of the active material mixture layer 43. More specifically, a plurality of blower nozzles 91 are arranged on both sides of the metal foil 11, and are arranged side by side toward the downstream side in the transport direction.

Of the air blowing nozzles 91, the air blowing nozzle 91 located at the most upstream side in the transport direction is arranged so as to blow air to the active material mixture layer 43 located near the inlet of the drying device 80. That is, the blowing nozzle 91 is arranged so as to blow air to the active material mixture layer 43 immediately after entering the drying device 80. It can be said that each air blowing nozzle 91 is arranged so as to blow air to the active material mixture layer 43 from a state before the active material mixture layer 43 is dried by the drying device 80. The air blowing nozzles 91 located on the downstream side in the transport direction blow air to the active material mixture layer 43 that has been dried, in other words, to the active material mixture layer 43 that contains less solvent.

Each blower nozzle 91 blows a gas toward each end portion 43A, 43B of the active material mixture layer 43. Specifically, each blow nozzle 91 blows gas toward the end portions 43A and 43B closest to each blow nozzle 91.

The blower nozzle 91 is arranged so as to face the upstream side in the transport direction. As shown in FIG. 4, when viewed from the thickness direction of the metal foil 11, the angle θ1 of the angle formed by the direction in which the blower nozzle 91 faces and the longitudinal direction of the metal foil 11, which is the direction in which both ends 43A and 43B extend, is It is preferably 0° or more and 10° or less. In the present embodiment, each blowing nozzle 91 is arranged so as to face the center of the metal foil 11 in the lateral direction. That is, the direction in which each blower nozzle 91 faces intersects the center of the metal foil 11 in the lateral direction.

Further, when viewed from the thickness direction of the metal foil 11, the central axis of the air blowing direction of each air blowing nozzle 91 is positioned outside the both ends 43A, 43B of the active material mixture layer 43 in the width direction of the active material mixture layer 43. ing. It can be said that in each blow nozzle 91, the blow port through which the gas is blown is located outside the end portions 43A, 43B closest to each blow nozzle 91 in the lateral direction of the metal foil 11. Thereby, the gas blown from each blow nozzle 91 reaches each end 43A, 43B from the outer side in the lateral direction of the metal foil 11 rather than the end 43A, 43B closest to each blow nozzle 91.

As shown in FIG. 5, the blowing nozzle 91 is arranged so as to be oblique to the both end portions 43A and 43B when viewed from the direction along the surface of the metal foil 11. When viewed from the longitudinal direction of the metal foil 11 among the directions along the surface of the metal foil 11, the angle θ2 formed by the direction of the blow nozzle 91 and the direction along the surface of the metal foil 11 is 15° or more and 30° or less. Preferably. The direction in which the air blowing nozzle 91 faces can also be said to be the air blowing direction of the gas blown from the air blowing nozzle 91.

The active material mixture layer 43 is conveyed in the drying device 80 while receiving the wind pressure of the gas blown by the blow nozzle 91 at both ends 43A and 43B. When the active material mixture layer 43 is dried by the drying device 80, the active material mixture layer 43 becomes the active material layer 12.

The pressure device 81 is located downstream of the drying device 80 in the transport direction of the metal foil 11. The pressure device 81 includes a pair of press rolls 82 arranged with the active material layer 12 sandwiched therebetween. Each press roll 82 of the present embodiment has a structure in which a heat medium can flow inside. Therefore, the peripheral surface of the press roll 82 is heated by the heat medium.

By passing between the pair of press rolls 82, the active material layer 12 is pressed and thereby densified. Further, the active material layer 12 is pressed while being heated, so that the active material layer 12 is further densified.

Next, a method for manufacturing an electrode for a lithium ion secondary battery using the manufacturing apparatus 41 will be described.
The coating device 60 forms the active material mixture layer 43 by applying the active material mixture 42 to the conveyed metal foil 11. This process is the coating process. After the coating step, a drying step of drying the active material mixture layer 43 formed on the metal foil 11 with the drying device 80 is performed. Further, at the same time as the drying step, the air blowing step of blowing air to the active material mixture layer 43 is performed.

In the air blowing step, air is blown obliquely toward both ends 43A and 43B when viewed from the direction along the surface of the metal foil 11 which is upstream from the air blowing nozzle 91. Since the air blowing nozzle 91 is arranged so as to be obliquely oriented with respect to both end portions 43A and 43B, when air is blown from the air blowing nozzle 91, both end portions 43A and 43B of the active material mixture layer 43 flow due to wind pressure. Then, it is formed so as to gradually become thinner toward the uncoated portion 22. The surfaces of both ends 43A and 43B of the active material mixture layer 43 are inclined in an arc shape so as to be recessed in the thickness direction of the active material mixture layer 43 by wind pressure.

The active material mixture 42 that has flowed by the wind pressure tries to bulge in a convex shape on the end face in the thickness direction of the active material mixture layer 43, as shown by the broken line in the figure, but the blower nozzle 91 is directed upstream in the transport direction. Therefore, the active material mixture 42 flows upstream in the transport direction. In the drying device 80, the drying of the active material mixture layer 43 progresses toward the downstream side in the transport direction. That is, since the active material mixture layer 43 is not dried as much as upstream in the transport direction, the active material mixture layer 43 has fluidity. Therefore, when the active material mixture 42 is continuously flowed toward the upstream side in the transport direction, the flowed active material mixture 42 is buried in the active material mixture layer 43 and is leveled flat. By disposing the blowing nozzle 91 as in the present embodiment, it is possible to manufacture the electrode sheet 10 in which unevenness of the active material layer 12 is less likely to occur due to the flowing active material mixture 42 and the active material layer 12 has less unevenness. ..

The active material mixture layer 43 together with the metal foil 11 is conveyed in the drying device 80 while maintaining the shapes of both ends 43A and 43B of the active material mixture layer 43 by the air blow from the air blow nozzle 91. By being transported in the drying device 80, drying progresses from the surface of the active material mixture layer 43, and the active material mixture layer 43 is solidified in a state where the shapes of both end portions 43A and 43B are maintained. When both ends 43A and 43B of the active material mixture layer 43 are gradually thinned toward the uncoated portion 22, for example, when the active material mixture layer 43 is formed by a coating process or subsequent cutting, The shape of both end portions 43A and 43B cannot be maintained until solidified. On the other hand, the shape can be maintained by carrying it while applying wind pressure to both ends 43A and 43B and drying it while making the shapes of both ends 43A and 43B. Then, the active material mixture layer 43 becomes the active material layer 12.

A pressing process is performed after the drying process and the blowing process. In the pressurizing step, the pressurizing device 81 pressurizes the active material layer 12. Thereby, the electrode sheet 10 is manufactured.
The operation of this embodiment will be described.

When manufacturing the electrode sheet 10, the active material layer 12 is pressed by the pressing device 81. Since both ends 23 of the active material layer 12 are gradually thinned toward the uncoated portion 22, the force applied to the metal foil 11 when pressed by the pressure device 81 is equal to the uncoated portion 22. It gets smaller as it gets closer to. Therefore, the amount of extension of the metal foil 11 when it is pressed by the pressing device 81 is smaller at both end portions 23 than at the central portion of the active material layer 12. Since both end portions 23 of the active material layer 12 are provided along the uncoated portion 22, the amount of extension of the portion of the metal foil 11 along the uncoated portion 22 is small.

The effects of this embodiment will be described.
(1) The both ends 23 of the active material layer 12 are formed so as to be gradually thinned toward the uncoated portion 22 by the blowing of gas by the blowing nozzle 91. When pressure is applied by the pressure device 81, the amount of extension of the portion of the metal foil 11 that contacts both ends 23 of the active material layer 12 can be reduced. Since both end portions 23 of the active material layer 12 are provided along the uncoated portion 22, when the active material layer 12 is pressed as compared with the case where the active material layer 12 has a constant thickness. The generation of wrinkles due to the rolling of the metal foil 11 due to pressure can be suppressed.

In particular, when the active material layer 12 is pressed by the press roll 82 whose peripheral surface is heated as in the present embodiment, the metal foil 11 is easily softened and deformed by the heat of the press roll 82, and the metal foil 11 is wrinkled. Is likely to occur. Specifically, heating the metal foil 11 lowers the yield point, and wrinkles are likely to occur on the metal foil 11 due to the lowering of the yield point. Therefore, when the electrode sheet 10 is manufactured using the press roll 82 whose peripheral surface is heated, a remarkable effect is obtained.

(2) By flowing the active material mixture 42 upstream in the transport direction, it is possible to manufacture the electrode sheet 10 in which the active material layer 12 has few irregularities. Therefore, the deposition of lithium from the active material layer 12 can be suppressed.

The embodiment can be modified and implemented as follows. The embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.
After forming the active material layer 12, an active material layer having a lower density than that of the active material layer 12 may be formed on both end portions 23 of the active material layer 12. When the pressure of the active material layer is applied by the pressure device 81, the force acting on the metal foil 11 increases as the density of the active material layer increases. Therefore, even if an active material layer having a density lower than that of the active material layer 12 is provided on both ends 23 of the active material layer 12, the same effect as that of the embodiment can be obtained.

The coating device 60 may be a comma coater, a lip coater or the like as long as it can apply the active material mixture.
The peripheral surface of the press roll 82 may not be heated. Further, the peripheral surface of the press roll 82 may be cooled.

The number of air blowing nozzles 91 may be changed as appropriate.
The arrangement position of the air blowing nozzle 91 may be appropriately changed as long as the both end portions 43A and 43B of the active material mixture layer 43 can be gradually thinned toward the uncoated portion 22.

The blowing nozzle 91 may be arranged so as to surround the active material mixture layer 43 located near the inlet of the drying device 80.
The air blowing nozzles 91 may be provided so that the air blowing direction can be changed by an actuator.

The angle θ2 may be changed. For example, when the electrode sheet 10 is curved in the thickness direction, the angle θ2 may be 15° or more and 30° or less. According to this, both ends of the active material mixture layer 43 can be efficiently dried and the shape can be fixed. Further, the control unit 92 may change the angle θ1 or the angle θ2 according to the basis weight of the active material mixture or the thickness of the active material mixture layer 43. In this case, the blower nozzle 91 is provided with a member capable of changing the angle θ1 and the angle θ2.

The air blowing nozzles 91 may be arranged so as to blow air toward the edges E1 and E2 of the metal foil 11 from the center side in the lateral direction of the metal foil 11 rather than the end portions 43A and 43B.
The electrode sheet 10 may have the active material layer 12 provided on only one surface of the metal foil 11.

Only one of the both ends 43A and 43B of the active material mixture layer 43 may be formed so as to gradually become thinner toward the uncoated portion 22.

E1, E2... Both edges, 10... Electrode sheet, 11... Metal foil, 12... Active material layer, 22... Uncoated part, 30... Electrode (electrode for lithium ion secondary battery), 41... Lithium ion secondary Device for manufacturing electrode for battery, 42... Active material mixture, 43... Active material mixture layer, 43A, 43B... Both ends, 50... Conveying device, 60... Coating device, 80... Drying device, 91... Blower nozzle ..

Claims (2)

A transport device for transporting a long metal foil,
A coating device for forming an active material mixture layer to be an active material layer by drying on the metal foil,
A drying device for drying the active material mixture layer,
When the portion located between the active material mixture layer and both edges in the lateral direction of the metal foil is an uncoated portion, the end faces of the active material mixture layer along the uncoated portion are directed. By blowing a gas, the end portion can be formed so as to gradually thin toward the uncoated portion, and a plurality of blowing nozzles arranged in the drying device,
A pressurizing device for pressurizing the active material layer,
Each blowing nozzle is for a lithium ion secondary battery that is arranged so as to face upstream in the transport direction of the metal foil and obliquely to the end when viewed from the direction along the surface of the metal foil. Electrode manufacturing equipment. A coating process of forming an active material mixture layer, which becomes the active material layer by drying, on the long metal foil to be transported.
A drying step of drying the active material mixture layer,
When the portion which is performed at the same time as the drying step and is located between the active material mixture layer and both edges in the lateral direction of the metal foil is an uncoated portion, the active material along the uncoated portion is formed. An air blowing step of blowing the gas toward the end of the material mixture layer to form the end so that the end is gradually thinned toward the uncoated portion,
A pressurizing step of pressurizing the active material layer,
In the blowing step, a gas is blown from a blowing nozzle that is arranged so as to face an upstream side in a conveying direction of the metal foil, and that is obliquely oriented with respect to the end portion when viewed from a direction along the surface of the metal foil. A method for manufacturing an electrode for a lithium ion secondary battery.