JP2018018678A - Method for manufacturing power storage device and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a loss of an active material layer.SOLUTION: A coating device 60 comprises a die head 62. A first active material mixture 43 and a second active material mixture 44 discharged from a discharge port 64 of the die head 62 are coated on a strip-like metal foil 42. A first coating part 45 applied with the first active material mixture 43 and a second coating part 46 applied with the second active material mixture 44 are formed in a longitudinal direction in a state in which the first coating part and the second coating part are arranged in a short direction of the strip-like metal foil 42. The second coating part 46 has a higher binder ratio than the first coating part 45. The second coating part 46 is formed so as to be along a side of an electrode facing a bottom wall of a case.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a power storage device and a power storage device.

  A power storage device such as a secondary battery or a capacitor includes a case and an electrode assembly housed in the case. The electrode assembly includes a plurality of electrodes stacked in layers while being insulated from each other (see, for example, Patent Document 1). The electrode includes a metal foil and an active material layer provided on at least one surface of the metal foil.

JP 2010-50111 A

  By the way, for example, when strong vibration acts on the power storage device, the electrode assembly may move within the power storage device, and the electrode assembly and the bottom wall of the case may collide. When a portion of the active material layer that faces the bottom wall of the case collides with the case, a defect occurs in which a part of the active material layer is dropped.

  An object of the present invention is to provide a method for manufacturing a power storage device that can suppress the loss of an active material layer, and a power storage device.

  A method for manufacturing a power storage device that solves the above problems includes an electrode that is a positive electrode or a negative electrode that includes an active material layer including an active material and a binder on at least one surface of a metal foil, and an electrode in which the electrodes are stacked in layers via an insulating material A method of manufacturing a power storage device comprising an assembly and a case in which an electrode assembly is accommodated, wherein an active material mixture containing an active material and a binder is applied to at least a part of the surface of the strip-shaped metal foil, A coating process for forming an electrode material, a cutting process for obtaining an electrode by cutting the electrode material, an assembling process for manufacturing an electrode assembly by stacking the electrodes, and a housing process for housing the electrode assembly in the case In the coating process, the electrode material to be at least one of the positive electrode and the negative electrode includes a first coating portion including an active material and a binder, an active material and the binder, and a bottom wall of the case In Along the portion to be the side that direction, to form a second coating section high proportion of the binder than the first coating unit.

  According to this, the portion of the active material layer along the side where the second coating portion is formed has a higher binder ratio than the other portions. The strength of the above-mentioned active material layer portion is improved by increasing the binder ratio. For this reason, the defect | deletion of an active material layer can be suppressed.

  Regarding the method for manufacturing the power storage device, the electrode assembly is a stacked type in which a plurality of electrodes and the insulating material are alternately stacked, and in the assembly step, the side of the dropped electrode is used as a contact surface. The electrodes may be stacked in contact with each other.

  When performing electrode lamination by dropping the electrode, the electrode is stopped by applying a portion of the active material layer along the side where the second coating portion of the dropped electrode is formed to the contact surface. At this time, an impact is applied to the portion of the active material layer along the side where the second coating portion of the electrode is formed, but the portion of the active material layer along the side where the second coating portion is formed is the binder ratio. Therefore, the active material layer is not easily lost. Therefore, even when the electrodes are dropped and stacked, the active material layer can be prevented from being lost.

  About the manufacturing method of the said electrical storage apparatus, the said coating process is the 1st storage part in which the 1st active material mixture containing a binder is stored, and the ratio of a binder higher than the said 1st active material mixture is 2nd. The strip-shaped metal foil is provided with each active material mixture from a die head having a manifold in which a second storage portion in which the active material mixture is stored is partitioned, and a slot for discharging each active material mixture from a discharge port. It may be carried out by discharging the ink.

  According to this, the active material mixture from which the ratio of a binder differs in a manifold can be stored. Since the active material mixture having a different binder ratio can be discharged from the discharge port, the first coating portion and the second coating portion can be easily formed.

  A power storage device that solves the above problems includes an electrode that is a positive electrode or a negative electrode including an active material layer containing an active material and a binder on at least one surface of a metal foil, and an electrode assembly in which the electrodes are stacked in layers via an insulating material And a case in which the electrode assembly is accommodated, wherein at least one of the electrodes has a side facing the bottom wall of the case, and the ratio of the binder is along the side and compared to other parts. Has a high area.

  According to this, the strength of the region of the active material layer along the side facing the bottom wall of the case is improved by increasing the binder ratio as compared with other portions. For this reason, the defect | deletion of an active material layer can be suppressed.

  According to the present invention, defects in the active material layer can be suppressed.

The perspective view of the secondary battery in embodiment. The perspective view of the electrode in an embodiment. Schematic which shows the manufacturing apparatus of the secondary battery in embodiment. The perspective view of the coating apparatus in embodiment. The 5-5 sectional view taken on the line of FIG. 4 which shows the coating apparatus in embodiment. The perspective view which shows the cutting device in embodiment. The perspective view which fractures | ruptures and shows a part of laminating apparatus in embodiment. The perspective view which shows the modification of a coating device. The perspective view which shows the modification of an electrode assembly. The perspective view which shows the modification of an electrode assembly.

Hereinafter, a method for manufacturing a power storage device and an embodiment of the power storage device will be described.
As shown in FIG. 1, a secondary battery 10 as a power storage device includes a case 11. The case 11 includes a bottomed square box-like case main body 12 that is open on one side, and a plate-like lid 13 that closes an opening portion of the case main body 12. The case body 12 includes a rectangular flat bottom wall 14 and four side walls 15 erected from the periphery of the bottom wall 14. The case body 12 and the lid 13 are joined by welding. The secondary battery 10 of the present embodiment is a lithium ion secondary battery, but may be any secondary battery such as a nickel hydride secondary battery. Further, the power storage device may be a capacitor including an active material layer.

  The secondary battery 10 includes an electrode assembly 20 housed in the case 11, and a positive electrode terminal 22 and a negative electrode terminal 23 that exchange power with the electrode assembly 20. The positive terminal 22 and the negative terminal 23 are fixed to the lid 13.

  As shown in FIG. 2, the electrode assembly 20 includes an electrode 24 that is a positive electrode or a negative electrode, and a separator 26 that is located between the positive electrode 24 and the negative electrode 24 as an isolation material. The positive electrode 24 and the negative electrode 24 are layered in a state of being insulated from each other by the separator 26. The electrode assembly 20 of this embodiment is a stacked type in which a plurality of individual electrodes 24 are stacked.

The electrode 24 includes a sheet-like metal foil 27. The metal foil 27 of the positive electrode 24 is, for example, an aluminum foil. The metal foil 27 of the negative electrode 24 is, for example, a copper foil.
The metal foil 27 includes a rectangular main body 28 and a tab 29 having a shape protruding from a first side 28 a that is one side of the main body 28. The metal foil 27 has a second side 28 b opposite to the first side 28 a of the main body 28. In the present embodiment, the first side 28a and the second side 28b are a pair of long sides facing each other. The first side 28 a of the main body 28 is also the first side 28 a of the electrode 24, and the second side 28 b of the main body 28 is also the second side 28 b of the electrode 24. The main body 28 may have a polygonal shape other than a square as long as the main body 28 has a shape having a first side and a second side that is the opposite side of the first side.

In a state where the electrode assembly 20 is accommodated in the case 11, the second side 28 b of each electrode 24 faces the bottom wall 14 of the case 11.
The electrode 24 includes an active material layer 30 on both surfaces of the main body 28. The active material layer 30 contains an active material for each polarity, a binder, and a conductive aid as necessary. Note that the electrode 24 that is a positive electrode or a negative electrode may include the active material layer 30 only on one surface of the main body 28.

  The active material layer 30 includes a first active material layer 31 and a second active material layer 32. The second active material layer 32 has a higher binder ratio than the first active material layer 31. The binder ratio is the binder ratio in each of the active material layers 31 and 32. For example, the binder ratio of the second active material layer 32 is 1.3 times or more compared to the binder ratio of the first active material layer 31. The binder ratio of the second active material layer 32 is determined within a range where the influence on the performance (output) of the secondary battery 10 can be allowed based on simulations and experiments.

  The boundary line B between the first active material layer 31 and the second active material layer 32 is closer to the second side 28b and parallel to the second side 28b. The first active material layer 31 is between the first side 28 a and the boundary line B. The second active material layer 32 is between the boundary line B and the second side 28b. Therefore, the area of the first active material layer 31 is larger than the area of the second active material layer 32. The second active material layer 32 is a region having a higher binder ratio than the first active material layer 31, which is another part, along the second side 28 b.

  The dimension of the second active material layer 32 along the short side of the main body 28 is provided within a range in which the influence on the performance (output) of the secondary battery 10 is allowable based on experiments and simulations. For example, the second active material layer 32 is provided within a range of 1 mm from the second side 28b toward the first side 28a.

Next, an apparatus for manufacturing the secondary battery 10 (an apparatus for manufacturing the power storage device) and a method for manufacturing the secondary battery 10 will be described.
As shown in FIG. 3, the manufacturing apparatus 40 of the secondary battery 10 includes an electrode material manufacturing apparatus 41, an electrode manufacturing apparatus 90, a stacking apparatus 100, and a housing apparatus 110. First, the electrode material manufacturing apparatus 41 will be described.

  As shown in FIG. 3 and FIG. 4, the electrode material manufacturing apparatus 41 applies the first active material mixture 43 and the second active material mixture 44 to the strip-shaped metal foil 42 to thereby apply the first coating unit 45 and the first coating material 45. 2 is an apparatus for producing a long electrode material 47 by performing a coating process for forming a coating portion 46. Of the directions along the surface of the strip-shaped metal foil 42, the direction along the long sides E1 and E2 is the longitudinal direction, and the direction orthogonal to the longitudinal direction along the surface of the strip-shaped metal foil 42 is the short direction. .

  The 1st active material mixture 43 and the 2nd active material mixture 44 knead | mix each active material for polarity, a conductive support agent, a binder, and a solvent. The second active material mixture 44 has a higher binder ratio than the first active material mixture 43. For example, the binder ratio of the second active material mixture 44 is 1.3 times or more compared to the binder ratio of the first active material mixture 43. The first active material mixture 43 forms the first active material layer 31. The second active material mixture 44 forms the second active material layer 32.

  The first coating part 45 is formed by applying the first active material mixture 43. The second coating part 46 is formed by applying the second active material mixture 44. The 1st coating part 45 and the 2nd coating part 46 are formed in the longitudinal direction of the strip | belt-shaped metal foil 42 in the state located in a line with the transversal direction of the strip | belt-shaped metal foil 42. FIG. The second coating unit 46 has a higher binder ratio than the first coating unit 45. The second coating part 46 is sandwiched by the first coating part 45 from the short direction of the strip-shaped metal foil 42. The 2nd coating part 46 is provided within the range of 1 mm toward the both sides of a transversal direction from the center of the transversal direction of the strip | belt-shaped metal foil 42, for example. In the present embodiment, the coating portions 45 and 46 are formed on both surfaces of the strip-shaped metal foil 42, but the coating portions 45 and 46 may be formed only on one surface of the strip-shaped metal foil 42.

  The strip-shaped metal foil 42 includes an exposed portion 48 along the long sides E1 and E2. Each exposed portion 48 is exposed with a constant width in the longitudinal direction of the strip-shaped metal foil 42. The exposed portion 48 is a portion where the coating portions 45 and 46 do not exist, and is a portion where the strip-shaped metal foil 42 is exposed. That is, in the coating process, the active material mixture 43 and 44 is applied to a part of the surface of the strip-shaped metal foil 42.

  The electrode material manufacturing apparatus 41 includes a supply device 51 that supplies the strip-shaped metal foil 42, a coating device 60 that applies the active material mixture 43, 44 to the strip-shaped metal foil 42 to form the coating portions 45, 46, Is provided. The electrode material manufacturing apparatus 41 includes a pressurizing device 81 that pressurizes the coating portions 45 and 46, and a winding device 55 that winds the strip-shaped metal foil 42 on which the coating portions 45 and 46 are formed.

  The supply device 51 includes a supply reel 52 around which a strip-shaped metal foil 42 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 strip-shaped metal foil 42 drawn out from the supply reel 52 has a longitudinal direction extending in the circumferential direction of the supply reel 52. Although illustration is omitted, in the present embodiment, a strip-shaped metal foil 42 in which coating portions 45 and 46 that have been coated and dried are formed on one surface of both surfaces is wound around the supply reel 52. Suppose that When manufacturing the positive electrode 24, an aluminum foil is used as the strip-shaped metal foil 42, and when manufacturing the negative electrode 24, a copper foil is used as the strip-shaped metal foil 42.

  The winding device 55 includes a winding reel 56 that winds the strip-shaped metal foil 42 and a second shaft 57. The take-up reel 56 is rotatably supported by the second shaft 57. The strip-shaped metal foil 42 is wound around the take-up reel 56 with the longitudinal direction extending in the circumferential direction of the take-up reel 56. Both the first shaft 53 and the second shaft 57, or the second shaft 57 is rotated by a driving source such as a motor (not shown), whereby the supply reel 52 and the take-up reel 56 are rotated. Thereby, the strip | belt-shaped metal foil 42 is conveyed along a conveyance path | route.

  The coating device 60 is located downstream of the supply device 51 in the transport direction of the strip-shaped metal foil 42. The coating apparatus 60 includes a die head 62 and a backup roll 61 that is disposed apart from the die head 62. The die head 62 includes a manifold 63 in which the active material mixture is stored, a discharge port 64 for the active material mixture 43 and 44, and a slot 79 for discharging the active material mixture 43 and 44 from the discharge port 64. . The die head 62 is disposed so that the discharge port 64 faces the strip-shaped metal foil 42. The slot 79 connects the manifold 63 and the discharge port 64.

  As shown in FIGS. 4 and 5, in the die head 62, the direction parallel to the short direction of the strip-shaped metal foil 42 is the width direction. The manifold 63 is divided into three storage portions 77 and 78 in the width direction by a partition wall 76. The three reservoirs 77 and 78 are two first reservoirs 77 and one second reservoir 78. The second reservoir 78 is sandwiched between the two partition walls 76. The first storage part 77 is located outside the second storage part 78 in the width direction. A first tank T1 is connected to the first reservoir 77 via a pump P. A second tank T2 is connected to the second reservoir 78 via a pump P. A first active material mixture 43 is stored in the first tank T1. A second active material mixture 44 is stored in the second tank T2.

  By driving the pump P, the first active material mixture 43 is stored in the first storage unit 77. Further, the first active material mixture 43 sent from the first reservoir 77 to the slot 79 is discharged from the discharge port 64. Similarly, the second active material mixture 44 is stored in the second storage part 78. The second active material mixture 44 sent from the second reservoir 78 to the slot 79 is discharged from the discharge port 64. The first active material mixture 43 and the second active material mixture 44 discharged from the discharge port 64 are applied to the strip-shaped metal foil 42.

  As shown in FIG. 3, a drying device 80 is disposed downstream of the coating device 60 in the transport direction of the strip-shaped metal foil 42. The drying device 80 is a device that supplies hot air to the coating units 45 and 46, for example.

  The pressurizing device 81 is located downstream of the drying device 80 in the conveying direction of the strip-shaped metal foil 42. The pressure device 81 includes a pair of press rolls 82 that sandwich the coating portions 45 and 46. The coating parts 45 and 46 are pressurized by passing between the press rolls 82, and the density is improved. Thereby, the electrode material 47 is manufactured.

Next, the electrode manufacturing apparatus 90 will be described.
The electrode manufacturing apparatus 90 is an apparatus that performs a cutting process of cutting the electrode 24 having a predetermined shape by cutting the long electrode material 47.

  As shown in FIG. 3, the electrode manufacturing apparatus 90 includes an electrode material supply apparatus 91 that supplies an electrode material 47. The electrode material supply device 91 includes an electrode material supply reel 92 around which the electrode material 47 manufactured by the electrode material manufacturing device 41 is wound, and a third shaft 93 on which the electrode material supply reel 92 is installed. The electrode material supply reel 92 is a take-up reel 56 around which the electrode material 47 manufactured by the electrode material manufacturing apparatus 41 is wound. That is, the take-up reel 56 around which the electrode material 47 is taken up is installed on the third shaft 93. The electrode material supply reel 92 is rotatably supported by the third shaft 93. The electrode material 47 drawn out from the electrode material supply reel 92 has a longitudinal direction extending in the circumferential direction of the electrode material supply reel 92.

  The electrode manufacturing apparatus 90 includes a pair of cylindrical transport rollers 94 that transport the electrode material 47 with the electrode material 47 interposed therebetween. The electrode material 47 is transported along the transport path by the rotation of the electrode material supply reel 92 and the transport roll 94.

  As shown in FIGS. 3 and 6, the electrode manufacturing apparatus 90 includes a cutting device 95 that cuts the electrode material 47. The cutting device 95 cuts the electrode 24 having a predetermined shape from the electrode material 47 by cutting the electrode material 47 along a predetermined cutting line L along the outer shape of the electrode 24. The planned cutting line L is a part of the electrode material 47 where cutting is planned. In the present embodiment, the planned cutting line L has the same shape as the contour of the electrode 24 having a predetermined shape, and is a closed ring.

  The planned cutting line L of the present embodiment is determined so that the two electrodes 24 are cut out in the short direction of the electrode material 47. The planned cutting line L includes a line L1 extending in the longitudinal direction of the electrode material 47 at the center in the lateral direction. By cutting the electrode material 47 along the line L1, the second sides 28b of the two electrodes 24 are formed. The line L1 is located in the second coating part 46. That is, the second side 28 b of the electrode 24 is formed by cutting the second coating portion 46. Since the second side 28b of the electrode 24 is a side facing the bottom wall 14 of the case 11, in the coating process, the second coating part 46 is provided along a portion that becomes a side facing the bottom wall 14 of the case 11. It can be said that it is formed.

  In the exposed portion 48, the planned cutting line L includes a line L2 extending in the longitudinal direction along the edge of the first coating portion 45, and a line L3 protruding from the midway position of the line L2 toward the long sides E1, E2. Prepare. By cutting the electrode material 47 along these lines L2 and L3, the first side 28a and the tab 29 are formed. The planned cutting line L includes a line L4 that connects the line L1 and the line L2. By cutting the electrode material 47 along the line L4, the short side of the main body 28 is formed. The 1st coating part 45 comprises the 1st active material layer 31 by being cut | disconnected, and the 2nd coating part 46 comprises the 2nd active material layer 32 by cut | disconnecting. The strip-shaped metal foil 42 constitutes the metal foil 27 by being cut.

  As shown in FIG. 6, the cutting device 95 of this embodiment is a laser device which cuts the electrode material 47 by irradiating a laser. The cutting device 95 cuts the electrode material 47 by irradiating the electrode material 47 with a laser in accordance with the planned cutting line L. As the cutting device 95, a die cutting device that cuts the electrode material 47 by sandwiching the electrode material 47 between a rotary die and an anvil roll, a punching device that punches the electrode material 47 by punching the electrode material 47, or the like is used. Also good. The electrode manufacturing apparatus 90 includes a transport device 96 that transports the electrode 24 cut by the cutting device 95. The transport device 96 transports the electrode 24 to a predetermined position.

  Next, the stacking apparatus 100 will be described. The laminating apparatus 100 is an apparatus that performs a laminating process as an assembling process for laminating the positive and negative electrodes 24 manufactured by the electrode manufacturing apparatus 90 and the separator 26.

  As shown in FIG. 7, the stacking apparatus 100 is an apparatus that stacks the electrodes 24 by using the fall of the electrodes 24 due to its own weight. The stacking apparatus 100 includes a positive and negative electrode 24 and an electrode transport apparatus 101 that transports the separator 26. The positive and negative electrodes 24 and the separator 26 are transported to the electrode transport device 101 by a device that holds the electrodes 24 and the separator 26 by suction, for example. The electrode transport apparatus 101 transports the electrode 24 so that the second side 28b of the electrode 24 is located downstream in the transport direction.

  The stacking apparatus 100 includes a storage unit 102 at the transport destination of the electrode 24 in the electrode transport apparatus 101. The storage portion 102 includes a bottom portion 103, a pair of guide wall portions 104 erected from the bottom portion 103, and a contact wall portion 105 provided between the pair of guide wall portions 104. The storage portion 102 is disposed such that the bottom portion 103 is inclined downward toward the contact wall portion 105.

  The electrode 24 and the separator 26 transported by the electrode transport device 101 fall from the electrode transport device 101 to the storage unit 102. The electrode 24 and the separator 26 dropped in the storage unit 102 slide on the bottom 103 or the electrode 24 dropped earlier. The electrode 24 stops when the second side 28b and the second active material layer 32 contact the contact surface 105a. The electrode 24 and the separator 26 conveyed by the electrode conveying device 101 are stacked. After a predetermined number of positive and negative electrodes 24 and separators 26 are stacked and all the stacking steps are completed, the electrode assemblies 20 are manufactured by fixing them together with tape or the like. The tab 29 of the electrode assembly 20 is electrically connected to the positive terminal 22 and the negative terminal 23.

  The housing device 110 is a device that performs a housing process of housing the electrode assembly 20 in the case 11. The accommodating device 110 accommodates the electrode assembly 20 such that the second side of each electrode 24 of the electrode assembly 20 faces the bottom portion 103.

After the electrode assembly 20 is accommodated in the case 11, the secondary battery 10 is manufactured by welding the case body 12 and the lid 13.
Next, the effect | action of the manufacturing method of the secondary battery 10 and the effect | action of the secondary battery 10 are demonstrated.

  In the stacking step, the electrode 24 that slides down is stopped by applying the second active material layer 32 along the second side 28b and the second side 28b of the electrode 24 to the contact surface 105a. The second active material layer 32 along the second side 28 b has a higher binder ratio than the first active material layer 31. For this reason, even if the second active material layer 32 along the second side 28b of the electrode 24 hits the contact surface 105a and an impact is applied to the second active material layer 32, the second active material layer 32 is not easily lost.

  The electrode assembly 20 is accommodated in the case 11 so that the second side 28 b of each electrode 24 faces the bottom wall 14. For example, when an impact is applied to the secondary battery 10, the impact is applied to the second side 28 b of the electrode 24 and the second active material layer 32. Even in this case, the second active material layer 32 is not easily lost.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The electrode 24 includes a second active material layer 32 having a higher binder ratio than the first active material layer 31 along the second side 28b of the metal foil 27. In the active material layer 30, the second side 28b The strength of the edge along is increased. Since the electrode assembly 20 is accommodated in the case 11 so that the second side 28b faces the bottom wall 14, for example, even when an impact is applied from the bottom wall 14 to the second side 28b, the second side 28b The active material layer 32 is not easily lost. Therefore, defects in the active material layer 30 can be suppressed.

  (2) In the stacking step, the electrode 24 is dropped by its own weight. And in order to stop the electrode 24 which falls, the 2nd edge | side 28b of the electrode 24 and the 2nd active material layer 32 are applied to the contact surface 105a. The second active material layer 32 has higher strength than the first active material layer 31. Therefore, the loss of the second active material layer 32 due to the contact between the contact surface 105a and the electrode 24 is suppressed.

  (3) By dividing the manifold 63 of the die head 62 into a plurality of storage portions 77 and 78, the active material mixtures 43 and 44 having different binder ratios can be stored. Since the active material mixtures 43 and 44 having different binder ratios can be discharged from the discharge port 64, the first coating portion 45 and the second coating portion 46 are easily formed.

  (4) By dividing the manifold 63 of the die head 62 into the plurality of storage portions 77 and 78, the active material mixtures 43 and 44 having different binder ratios can be applied by one application. For this reason, for example, the manufacturing process can be performed without increasing the number of processes.

In addition, you may change embodiment as follows.
As shown in FIG. 8, the coating apparatus 120 may be a comma coater. The coating apparatus 120 attaches to the surface of the coating roll 122 the storage tank 121 that stores the active material mixture 43, 44, the cylindrical coating roll 122, and the active material mixture 43, 44 supplied from the storage tank 121. And a substantially cylindrical comma roll 123 that adjusts the supply amount of the active material mixture 43, 44. The coating apparatus 120 includes a cylindrical backing roll 124 that guides the strip-shaped metal foil 42. Each roll 122, 123, 124 is arranged in parallel.

  The storage tank 121 includes a partition wall 133 that partitions the inside of the storage tank 121 into two first storage portions 131 and one second storage portion 132. Two first storage portions 131 in which the first active material mixture 43 is stored are provided across a second storage portion 132 in which the second active material mixture 44 is stored. As each roll 122, 123, 124 rotates, the active material mixture 43, 44 attached to the surface of the coating roll 122 is applied to the strip-shaped metal foil 42.

  As shown in FIG. 9, the electrode assembly 140 may be a winding type in which a long electrode 141 is wound. In the above-described embodiment, the assembly process in the manufacturing process includes a stacking process in which the positive and negative electrodes 24 and the separator 26 are stacked. However, in the case of a winding type, a winding process is provided instead. The positive and negative electrodes 141 include a long metal foil 142. The metal foil 142 includes a plurality of tabs 143 on the first side 142a which is one long side. The electrode 141 includes an active material layer 144 on at least one side. The active material layer 144 includes a first active material layer 145 and a second active material layer 146. The second active material layer 146 extends along the second side 142b that is the opposite side of the first side 142a.

  The second active material layer 32 only needs to be provided at least on the electrode with the active material layer exposed at the outer periphery of the electrode assembly, and may be formed only on one electrode, for example, the negative electrode. . As an example, as shown in FIG. 10, in a lithium ion secondary battery, a separator-containing positive electrode 202 in which a positive electrode 201 is accommodated in a bag-like separator 200 and a negative electrode 203 are stacked. The electrode assembly 204 is formed, and only the active material layer 30 of the negative electrode 203 is exposed on the outer periphery of the electrode assembly 204. In such a structure, it is only necessary that the second active material layer 32 be formed only at least on the negative electrode 203.

  The first coating portion 45 and the second coating portion 46 are formed in the coating process for the electrode material 47 to be at least one of the positive electrode 24 and the negative electrode 24, and the other electrode 24 For the electrode material 47 to be, only one coated portion may be formed.

In the coating process, the active material mixture 43, 44 may be applied to the entire surface of the strip-shaped metal foil 42.
The laminating apparatus 100 may be an apparatus in which the electrode 24 and the separator 26 are alternately conveyed by the conveying device 96 that lifts and conveys the electrode 24 and the separator 26. That is, the laminating process may be performed by a method other than sliding off using its own weight.

  In the case where the two electrodes 24 are not cut out side by side in the short direction of the electrode material 47, the electrode material 47 includes one first coating portion 45 and one second coating portion 46 on the strip-shaped metal foil 42. It may be a structure. Moreover, when cutting out the some electrode 24 along with the transversal direction of the electrode material 47, you may change the number of the 1st coating parts 45 and the 2nd coating parts 46 according to the number.

  In the embodiment, the first coating portion 45 and the second coating portion 46 are formed by applying the active material mixture 43, 44 having a different binder ratio to the strip-shaped metal foil 42. However, the strip-shaped metal foil 42 is formed. One kind of active material mixture may be applied to the substrate. In this case, before applying the active material mixture to the strip-shaped metal foil 42, a binder is applied in the longitudinal direction of the strip-shaped metal foil 42. Then, the active material mixture is applied to the portion where the binder is applied by the coating apparatus 60 and the portion where the binder is not applied. Of the portion where the active material mixture is applied, the portion where the binder is not applied becomes the first coating portion 45. Of the portion where the active material mixture is applied, the portion where the binder is applied becomes the second coating portion 46 having a higher binder ratio than the first coating portion 45. In this case, it is not necessary to use a plurality of types of active material mixture, and the coating device 60 may not have a plurality of storage portions.

  In addition, when apply | coating a binder over the whole surface of the strip | belt-shaped metal foil 42, it is necessary to reduce the quantity of the binder contained in an active material mixture. Then, there are few binders of an active material mixture, and stability of an active material mixture falls. When the electrode 24 is manufactured, by applying a binder only to a portion where the active material layer 30 is likely to be lost, it is possible to prevent the active material layer 30 from being lost while ensuring the stability of the active material mixture. .

  -Moreover, it is an electrode provided with an active material layer containing an active material and a binder on at least one surface of the metal foil, and an edge on which an end surface of the active material layer is exposed on the outer periphery, and the active material layer is the active material An electrode having a region with a high binder ratio along at least one side where the end face of the layer is exposed can be used for, for example, a laminate-type secondary battery without a case. Such an electrode can use one side of a region having a high binder ratio for collision during conveyance or positioning for stacking. When the conveyance speed of the production line is increased for the purpose of improving production efficiency, the active material layer is likely to be lost and the active material particles are peeled off due to the above-mentioned guidance for conveyance and positioning for lamination. When the electrode described above is used, it is possible to manufacture an electrode assembly with high production efficiency while suppressing defects in the active material layer. Therefore, in this case, as long as it is one side of the individual electrode constituting the stacked electrode assembly, it does not necessarily have to be one side facing the bottom wall of the case.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery (electric storage device), 11 ... Case, 14 ... Bottom wall, 20 ... Electrode assembly, 24 ... Electrode, 26 ... Separator (insulating material), 27 ... Metal foil, 28a ... First side, 28b ... 2nd side, 29 ... tab, 30 ... active material layer, 40 ... secondary battery manufacturing device (power storage device manufacturing device), 43 ... first active material mixture, 44 ... second active material mixture, 45 ... 1st coating part, 46 ... 2nd coating part, 47 ... electrode material, 62 ... die head, 63 ... manifold, 64 ... discharge port, 77 ... 1st storage part, 78 ... 2nd storage part, 79 ... slot, 105a: Contact surface.

Claims (4)

An electrode which is a positive electrode or a negative electrode provided with an active material layer containing an active material and a binder on at least one side of the metal foil;
An electrode assembly in which the electrodes are stacked in layers via an insulating material;
A method of manufacturing a power storage device comprising a case in which the electrode assembly is accommodated,
An application step of applying an active material mixture containing an active material and a binder to at least a part of the surface of the belt-shaped metal foil to form an electrode material;
A cutting step of obtaining the electrode by cutting the electrode material;
An assembly process for manufacturing the electrode assembly by stacking the electrodes;
A housing step of housing the electrode assembly in the case,
In the coating step, the electrode material to be at least one of the positive electrode and the negative electrode includes a first coating portion including an active material and a binder, the active material and the binder, and a bottom of the case A method for manufacturing a power storage device, comprising: a second coating portion that has a higher binder ratio than the first coating portion along a side that faces the wall. The electrode assembly is a laminated type in which a plurality of electrodes and the insulating material are alternately laminated,
2. The method for manufacturing a power storage device according to claim 1, wherein, in the assembling step, the electrodes are stacked by bringing the side of the dropped electrode into contact with a contact surface. The coating process includes
A first storage part in which a first active material mixture containing a binder is stored, and a second storage part in which a second active material mixture having a higher binder ratio than the first active material mixture is partitioned. A manifold,
3. The power storage device according to claim 1, wherein the power storage device is performed by discharging each active material mixture to the strip-shaped metal foil from a die head including a slot for discharging each active material mixture from a discharge port. Manufacturing method. An electrode which is a positive electrode or a negative electrode provided with an active material layer containing an active material and a binder on at least one side of the metal foil;
An electrode assembly in which the electrodes are stacked in layers via an insulating material;
A case in which the electrode assembly is accommodated,
At least one of the electrodes includes a side facing the bottom wall of the case, and has a region with a higher binder ratio than other parts along the side.

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