JP6046538B2 - Manufacturing method of secondary battery - Google Patents

Description

  The present invention relates to a method for manufacturing a secondary battery having a positive electrode and a negative electrode in which a mixture layer is formed on the surface of a current collector.

Conventionally, in a secondary battery manufacturing process, powder containing an active material (a positive electrode active material and a negative electrode active material) is supplied to the surface of a sheet-like current collector (a positive electrode current collector and a negative electrode current collector). Thus, a positive electrode and a negative electrode are manufactured by forming a mixture layer (a positive electrode mixture layer and a negative electrode mixture layer).
In the manufacturing process of the secondary battery, an electrode body is manufactured by winding a separator between such a positive electrode and a negative electrode, and pressing the wound product.
In the manufacturing process of the secondary battery, the electrode body and the current collecting terminal are joined by ultrasonic welding or the like, the electrode body is housed in the battery container, and the electrolytic solution is infiltrated into the electrode body to manufacture the secondary battery. Yes.

In such a secondary battery manufacturing process, the positive electrode and the negative electrode (in particular, the innermost side, that is, the portion wound first) are largely bent during winding and pressing.
Further, when the electrode body is joined to the current collector terminal by ultrasonic welding, the current collector vibrates due to the ultrasonic waves.
During such winding, pressing, welding, and the like, the mixture layer may peel from the current collector. In this case, the charge / discharge characteristics of the secondary battery are degraded.

As a technique for preventing peeling of the mixture layer, for example, there is a technique disclosed in Patent Document 1.
In the technique disclosed in Patent Document 1, a first layer containing a binder is formed on a current collector, and a second layer (mixture layer) containing an active material is formed on the first layer. Form. In the technique disclosed in Patent Document 1, the peel strength of the second layer is improved by making the binding force of the first layer stronger than the second layer.

In the case where the second layer is formed on the first layer as in the technique disclosed in Patent Document 1, the first layer is disposed at any location between the second layer and the current collector. There will be intervening layers.
For this reason, in the technique disclosed in Patent Document 1, the electrical resistance between the current collector and the active material may increase.

As a means for suppressing such an increase in electrical resistance, for example, as shown in FIG. 18, a binder is pattern-applied on the current collector to form a first grid-like or dot-like first view. Means for forming the layer are contemplated.
In this case, there exists a region P where the first layer is not formed at both ends in the width direction of the second layer (both left and right ends in FIG. 18).

In the region P where the first layer is not formed, the second layer is bound only by the binding force between the particles of the active material. At the center in the width direction of the second layer, the second layer formed in the region where the first layer is not formed has the second layer formed on the first layer around it. Therefore, by being supported from four directions, the binding property with the current collector can be maintained only by the binding force of the active material (that is, the peel strength is high). On the other hand, in the region P at both ends in the width direction of the second layer, there is only a part of the second layer formed on the first layer around it, so the second layer of the region P is There is a possibility that the supporting force from the periphery is reduced, and the peel strength of the second layer in the region P is reduced.
Therefore, in this case, when the secondary battery is manufactured, the second layer may peel from the current collector to the inner side in the width direction, starting from the region P where the first layer is not formed. There is sex.

  As described above, in the prior art, it is impossible to achieve both suppression of an increase in electrical resistance and improvement of peel strength.

JP 2004-79370 A

  The present invention has been made in view of the situation as described above, and provides a method for manufacturing a secondary battery capable of both suppressing an increase in electrical resistance and improving peel strength.

  A method for manufacturing a secondary battery according to the present invention is a method for manufacturing a secondary battery having a positive electrode and a negative electrode in which a mixture layer is formed on the surface of the current collector, wherein the binder is patterned on the surface of the current collector Applying the positive electrode by performing a step of applying and forming a coating portion, and a step of supplying a powder containing mixture particles onto the surface of the current collector and the binder to form the mixture layer In the step of manufacturing at least one of the negative electrode and forming the application portion, the binder is continuously applied to regions corresponding to both end portions in the width direction of the mixture layer. Forming the application part that is continuous in the length direction, forming the application part by partially applying the binder to a region inside the width direction both ends of the mixture layer, the application part is Forming a non-coated portion as a non-formed region, Than is.

  In the method for manufacturing a secondary battery according to the present invention, in the step of forming the coating portion, the binder is patterned in the width direction of the mixture layer and continuously in the length direction of the mixture layer. It is applied to form the stripe-shaped application part along the length direction of the mixture layer.

  In the method for manufacturing a secondary battery according to the present invention, the width of the application part formed in the region corresponding to both ends in the width direction of the mixture layer is a region inside the both ends in the width direction of the mixture layer. It is longer than the width of the application part to be formed.

  The present invention has an effect that it is possible to achieve both an increase in electrical resistance and an improvement in peel strength.

The partial cross section figure of a secondary battery. Explanatory drawing of an electrode body. Explanatory drawing which shows a binder liquid supply apparatus. The perspective view which shows a gravure roll. Explanatory drawing which shows an application part and a non-application part. Explanatory drawing which shows a mode that a positive electrode is manufactured. Explanatory drawing which shows an application part, a non-application part, and a mixture layer. Explanatory drawing which shows the positive electrode after slit processing. Explanatory drawing which shows the negative electrode after slit processing. Explanatory drawing which shows a mode that an electrode body is manufactured. (A) The figure which shows a mode that a positive electrode, a negative electrode, and a separator are wound. (B) The figure which shows a mode that a press work is performed. Explanatory drawing which shows the site | part which measured the peeling strength of the negative electrode electrical power collector of this embodiment. Explanatory drawing which shows the result of having measured peeling strength. The figure which shows the result of having measured the precision of the position of the width direction both ends of a negative mix layer. The top view which shows the modification of the application part in this embodiment. (A) The figure which shows the application part formed in planar view lattice shape. (B) The figure which shows the application part formed in planar view dot shape. (C) The figure which shows the application part formed in planar view diagonal stripe form. Explanatory drawing which shows the electrode body manufactured by laminating | stacking a substantially plate-shaped positive electrode and negative electrode. Explanatory drawing which shows the gravure roll which apply | coats binder liquid in planar view grid | lattice form. (A) Top view. (B) The figure which shows the state by which the binder liquid was lifted. Explanatory drawing which shows the site | part which measured the peeling strength of the negative electrode collector which formed the application part in planar view grid shape. The top view which shows the electrical power collector in a prior art. (A) The figure which shows the electrical power collector with which a binder is apply | coated by planar view grid | lattice form. (B) The figure which shows the electrical power collector with which a binder is apply | coated in planar view dot shape.

  Below, the manufacturing method of the secondary battery of this embodiment is demonstrated.

  First, a schematic configuration of the secondary battery 1 will be described.

The secondary battery 1 of the present embodiment is a lithium ion secondary battery. The target to which the present invention is applied is not limited to the lithium ion secondary battery, and can be applied to other secondary batteries.
As shown in FIG. 1, the secondary battery 1 includes an exterior 10, an electrode body 20, an external terminal 60, and the like.

  The exterior 10 is a hollow battery container configured by closing a bottomed rectangular tube-shaped storage unit 11 having an open surface with a flat lid 12. An electrode body 20 is accommodated in the exterior 10.

  As shown in FIG. 2, the electrode body 20 is a wound electrode body including a positive electrode 30, a negative electrode 40, and a separator 50.

The positive electrode 30 and the negative electrode 40 are configured by forming a positive electrode mixture layer 32 and a negative electrode mixture layer 42 on the surface (both sides or one side surface) of a sheet-like positive electrode current collector 31 and a negative electrode current collector 41. .
In the positive electrode 30 and the negative electrode 40 of the present embodiment, the mixture layers 32 and 42 are formed on both surfaces of the current collectors 31 and 41, respectively.

The positive electrode mixture layer 32 is formed continuously from one end to the other end in the width direction of the positive electrode 30 (left and right direction in FIG. 2).
The negative electrode mixture layer 42 is continuously formed from the other end portion in the width direction of the negative electrode 40 to one end side.

  In the positive electrode 30 and the negative electrode 40, portions where the mixture layers 32 and 42 are not formed are formed as the non-mixture layers 33 and 43. That is, the non-mixture layers 33 and 43 have opposite positions in the width direction.

The separator 50 is a sheet-like member made of resin or the like. The width of the separator 50 is shorter than the width of the positive electrode 30 and the negative electrode 40.
The separator 50 is interposed between the positive electrode 30 and the negative electrode 40 in a state where the positions of both end portions in the width direction are located in the middle portions of the non-mixture layers 33 and 43 in the width direction.

The electrode body 20 is configured by winding the positive electrode 30, the negative electrode 40, and the separator 50 with the width direction of the positive electrode 30 as the winding axis direction, and pressing the wound one (see FIG. 10). ).
The electrode body 20 functions as a power generation element of the secondary battery 1 when the electrolyte injected into the exterior 10 penetrates.

As shown in FIG. 1, the external terminal 60 is attached to the lid portion 12 via the insulating members 62 and 63 in a state where a part of the external terminal 60 protrudes from the outer surface of the exterior 10 to the upper side (outward) of the secondary battery 1. On the other hand, it is fixed in an insulated state. The external terminal 60 is electrically connected to the positive electrode 30 and the negative electrode 40 via the current collecting terminal 61. The current collecting terminal 61 is joined to the non-mixture layers 33 and 43 by ultrasonic welding.
The external terminal 60 and the current collecting terminal 61 function as an energization path for taking out the electric power stored in the electrode body 20 to the outside or taking in the electric power from the outside into the electrode body 20.

In the secondary battery 1 configured in this manner, the charge / discharge characteristics are deteriorated when the mixture layers 32 and 42 are separated from the current collectors 31 and 41.
As described above, when the mixture layers 32 and 42 may be separated from the current collectors 31 and 41, for example, when the positive electrode 30 and the negative electrode 40 are wound, the current collecting terminals 61 are not connected to the non-current collector terminals 61 and 41, respectively. For example, when ultrasonically welding the mixture layers 33 and 43.

  The manufacturing method of the secondary battery of this embodiment prevents the deterioration of the charge / discharge characteristics due to the peeling of the mixture layers 32 and 42 by improving the peeling strength of the current collectors 31 and 41.

  Next, the procedure of the secondary battery manufacturing method will be described.

First, in the manufacturing method of the secondary battery, the mixture layers 32 and 42 are formed on the current collectors 31 and 41 to manufacture the positive electrode 30 and the negative electrode 40.
In the following, the procedure for manufacturing the positive electrode 30 will be described.

In forming the positive electrode mixture layer 32, in the secondary battery manufacturing method, the binder liquid A is applied to the positive electrode current collector 31 using a binder liquid supply device 70 as shown in FIG.
As shown in FIG. 3, the binder liquid supply device 70 includes a rubber roll 71, a gravure roll 72, a liquid pan 73, a blade 74, and the like.

The rubber roll 71 is a roll whose axial direction is the width direction of the positive electrode current collector 31 (direction perpendicular to the vertical direction of the paper surface and the horizontal direction of the paper surface in FIG. 3) and whose outer diameter is larger than that of the gravure roll 72. . The bottom (lower end) of the rubber roll 71 is in contact with the other side of the positive electrode current collector 31.
The positive electrode current collector 31 extends over the rubber roll 71 and extends upward.

As shown in FIGS. 3 and 4, the gravure roll 72 is a roll for applying the binder liquid A to the positive electrode current collector 31. The gravure roll 72 has the width direction of the positive electrode current collector 31 as an axial direction, and a plurality of groove portions 72 a and 72 b are formed on the outer peripheral surface.
The gravure roll 72 is opposed to the rubber roll 71 with the positive electrode current collector 31 in between, and the top (upper end) is in contact with one side surface of the positive electrode current collector 31.

The groove portions 72a and 72b are substantially circular recesses formed endlessly along the circumferential direction of the gravure roll 72 without the position of the gravure roll 72 in the axial direction changing. A plurality of grooves 72 a and 72 b are formed at intervals in the axial direction of the gravure roll 72.
In the axial direction of the gravure roll 72, the groove portions 72a located at both ends are longer in width than the other groove portions 72b.

In the following, such groove portions 72a located at both end portions will be referred to as “both end groove portions 72a”.
Hereinafter, the groove portions 72b other than the groove portions 72a at both ends are referred to as “inner groove portions 72b”.

The liquid pan 73 is a container for storing the binder liquid A. The lower part of the gravure roll 72 is accommodated in the liquid pan 73. That is, the lower part of the gravure roll 72 is in a state of being immersed in the binder liquid A of the liquid pan 73.
The gravure roll 72 rotates to cause the binder liquid A to adhere to the outer peripheral surface, and to allow the binder liquid A to enter the grooves 72a and 72b.

The binder liquid A is a liquid in which the binder is dispersed or dissolved in the dispersion medium.
As the binder, known ones such as SBR (styrene butadiene copolymer), polyacrylic acid, and polyvinylidene fluoride can be used. As the dispersion medium, water or an organic solvent can be used. The binder liquid A may contain a thickener or a surfactant in order to adjust the viscosity and wettability of the coating liquid. A well-known thing can be used as the said thickener or the said surfactant. The binder concentration in the binder liquid A is about 1.5 to 40% by weight.

The blade 74 is a member formed in a substantially triangular shape when viewed from the axial direction of the gravure roll 72. The blade 74 extends along the axial direction of the gravure roll 72, and the tip part comes into contact with the outer peripheral surface of the gravure roll 72 (part where the grooves 72 a and 72 b are not formed).
Such a portion of the gravure roll 72 that contacts the blade 74 is located downstream of the gravure roll 72 in the rotational direction of the gravure roll 72 and upstream of the gravure roll 72 in the rotational direction of the gravure roll 72. is there.

The blade 74 scrapes off the binder liquid A adhering to the outer peripheral surface of the gravure roll 72 before the binder liquid A adhering to the outer peripheral surface of the rotating gravure roll 72 contacts the positive electrode current collector 31.
Therefore, the gravure roll 72 has a binder liquid only in each of the groove portions 72a and 72b in a range from the downstream side in the rotation direction to the top portion (that is, the contact portion with the positive electrode current collector 31) from the contact portion with the blade 74. A exists.

  In the manufacturing method of the secondary battery, one side surface of the positive electrode current collector 31 that transports the binder liquid A that has entered the groove portions 72a and 72b of the gravure roll 72 by rotating the rolls 71 and 72 and the like. Apply to.

At this time, the binder liquid A is transferred to one side surface of the positive electrode current collector 31 along the shape of the groove portions 72 a and 72 b of the gravure roll 72.
Therefore, as shown in FIG. 5, the binder liquid A does not change the position in the axial direction of the gravure roll 72, that is, the width direction of the positive electrode current collector 31, and thus the circumferential direction of the gravure roll 72, that is, the positive electrode collection. It is applied continuously in the length direction of the electric body 31.

  Thereby, in the manufacturing method of the secondary battery, the binder liquid A is pattern-coated continuously in the length direction of the positive electrode mixture layer 32 while being spaced apart in the width direction of the positive electrode mixture layer 32.

  Here, “the pattern application of the binder liquid A” means that the binder liquid A is not applied over the entire surface of the application area of the binder liquid A, but a portion where the binder liquid A is applied becomes a predetermined pattern (pattern). Is to apply. When the binder liquid A is applied in a pattern, the binder liquid A is partially applied in the application area of the binder liquid A, and the application portions 31a and 31b, which are the portions where the binder liquid A is applied, and the binder liquid A The non-application part 31c which is a part which is not apply | coated is formed.

  In the method of manufacturing the secondary battery, before forming the positive electrode mixture layer 32 in this way, the application portions 31a and 31b having a stripe shape in plan view along the length direction of the positive electrode current collector 31 are formed into positive electrode current collectors. A process of forming on one side surface (surface) of the electric body 31 is performed.

In the following, the application portions 31a located at both ends in the width direction of the positive electrode current collector 31 in the application portions 31a and 31b are referred to as “application portions 31a at both ends”.
Hereinafter, the application part 31b other than the application part 31a at both ends will be referred to as an “inner application part 31b”.

As described above, the width of the groove 72a at both ends of the gravure roll 72 is longer than the width of the inner groove 72b (see FIG. 4).
For this reason, in this embodiment, the width D1 of the application part 31a at both ends is longer than the width D2 of the inner application part 31b. Further, the widths D1 of the application portions 31a at both ends are the same.

  In addition, the width | variety of the application part of both ends does not necessarily need to be the same width | variety mutually.

The positions of the end portions on the outer side in the width direction of the coating portions 31a at both ends are arranged at the same positions as the positions of the end portions on the outer side in the width direction of the positive electrode mixture layer 32 (see FIG. 7).
That is, in the manufacturing method of the secondary battery, the application region of the binder liquid A corresponds to the region where the positive electrode mixture layer 32 is formed, and the inner application portion 31b is located inside the region where the positive electrode mixture layer 32 is formed. Form.

As shown in FIG. 6, after forming the application portions 31 a and 31 b, in the secondary battery manufacturing method, the application portions 31 a and 31 b are directed upward by the feed roll 75 disposed above the rubber roll 71. In this state, the positive electrode current collector 31 is conveyed in the right direction.
In the secondary battery manufacturing method, the powder B containing the positive electrode mixture particles is supplied to one side surface of the positive electrode current collector 31.

The mixture particles mean particles in the mixture layer, and include, for example, active material particles, conductive particles, and a binder in addition to active material particles, conductive particles, and a powdery binder. It means granulated particles as well as mixtures thereof.
In other words, the positive electrode mixture particles mean particles that constitute the positive electrode mixture layer 32. For example, in addition to the positive electrode active material particles, the conductive particles, and the powdered binder, the positive electrode active material particles, the conductive particles are used. Means granulated particles containing a conductive particle and a binder, and a mixture thereof.

When supplying the powder B containing the positive electrode mixture particles, for example, a hopper 81 and a spreading roll 82 are used in the method for manufacturing a secondary battery.
The hopper 81 is disposed above the positive electrode current collector 31 and has upper and lower ends opened. In the hopper 81, the powder B is stored.
The spreading roll 82 is disposed in the lower opening of the hopper 81, and a plurality of depressions are formed on the outer peripheral surface.

In the secondary battery manufacturing method, the spreading roll 82 is rotated to move the depression to the top of the spreading roll 82, and the powder B is supplied to the depression of the spreading roll 82.
And in the manufacturing method of a secondary battery, the spreading roll 82 is further rotated to move the depression supplied with the powder B to the vicinity of the bottom of the spreading roll 82, and the powder B is placed on one side of the positive electrode current collector 31. Drop it.

  As a result, as shown in FIGS. 6 and 7, in the method for manufacturing the secondary battery, the powder B is supplied to the region where the positive electrode mixture layer 32 is formed, that is, the application portions 31a and 31b and the non-application portion 31c. To do.

After supplying the powder B, the powder B is compressed in the manufacturing method of the secondary battery.
At this time, in the method for manufacturing the secondary battery, for example, a pair of rolls 83 arranged to face each other with the positive electrode current collector 31 interposed therebetween are rotated and brought close to each other.

  The pair of rolls may be compressed while heating the powder.

  Thereby, in the manufacturing method of the secondary battery, the positive electrode mixture layer 32 is formed on one side surface of the positive electrode current collector 31.

Such a positive electrode mixture layer 32 is always formed on the positive electrode current collector 31 at both ends in the width direction with the application portions 31a at both ends in between.
Therefore, in the method for manufacturing a secondary battery, both end portions in the width direction of the positive electrode mixture layer 32 can be bonded to the positive electrode current collector 31 by the application portions 31a at both ends.

  For this reason, the secondary battery manufacturing method binds the positive electrode current collector 31 and the positive electrode mixture layer 32 with a strong force at the both ends in the width direction of the positive electrode mixture layer 32 by the binding force of the application portions 31a at both ends. it can.

  That is, the secondary battery manufacturing method can improve the peel strength at both ends in the width direction of the positive electrode mixture layer 32.

  As described above, in the method for manufacturing the secondary battery according to the present embodiment, the powder B is supplied onto one side surface (non-applied portion 31 c) and the binder (each applied portion 31 a and 31 b) of the positive electrode current collector 31. A step of forming the mixture layer 32 is performed.

  In the manufacturing method of the secondary battery, the positive electrode mixture layer 32 is formed on the other side surface of the positive electrode current collector 31 in the same procedure as the case where the positive electrode mixture layer 32 is formed on one side surface of the positive electrode current collector 31. .

As shown in FIG. 7 and FIG. 8, after forming the positive electrode mixture layer 32 on both surfaces of the positive electrode current collector 31, in the secondary battery manufacturing method, with respect to both ends in the width direction of the positive electrode current collector 31. By performing slit processing, the width of the positive electrode current collector 31 is cut into a predetermined width.
At this time, in the method for manufacturing the secondary battery, for example, a cutting tool is disposed on the conveyance path of the positive electrode current collector 31 and both ends in the width direction of the positive electrode current collector 31 are cut.

  Thereby, in the manufacturing method of the secondary battery, the positive electrode mixture layer 32 is formed from one end in the width direction to the other end in the width direction, and the positive electrode non-mixture layer 33 is formed at the other end in the width direction. 30 is manufactured.

In such slit processing, the blade tool is disposed at one end in the width direction of the positive electrode mixture layer 32 (the end opposite to the side where the positive electrode non-mixture layer 33 is formed, that is, the right end in FIG. 8). As a result, a shearing force is applied.
Therefore, when the peel strength at one end in the width direction is low, the positive electrode mixture layer 32 may peel from the positive electrode current collector 31 to the inner side in the width direction with the one end in the width direction as a base point due to the shearing force. is there.

Therefore, in the method for manufacturing a secondary battery according to the present embodiment, the positive electrode mixture layer is formed by always forming the application portions 31a at both ends between the both ends in the width direction of the positive electrode mixture layer 32 and the positive electrode current collector 31. The peel strength at both ends in the width direction of 32 is improved.
According to this, the method for manufacturing a secondary battery can prevent the positive electrode mixture layer 32 from being separated from the positive electrode current collector 31 when the positive electrode current collector 31 is cut.

  As shown in FIG. 9, in the method for manufacturing a secondary battery, the negative electrode 40 is manufactured by the same procedure as that for manufacturing the positive electrode 30.

At this time, in the method for manufacturing a secondary battery, powder containing negative electrode mixture particles is supplied to the negative electrode current collector 41.
The negative electrode mixture particle means a particulate material constituting the negative electrode mixture layer 42. For example, in addition to the negative electrode active material particles, the conductive particles, and the powdery binder, the negative electrode active material particles, the conductive particles, And granulated particles containing a binder, and a mixture thereof.

  That is, the mixture particles according to the present invention become the positive electrode mixture particles when producing a positive electrode, and the negative electrode mixture particles when producing a negative electrode.

  In addition, the manufacturing method of a secondary battery should just form at least any one of a positive electrode and a negative electrode by forming each application part in at least any one of a positive electrode collector and a negative electrode collector.

  As shown in FIG. 10, after manufacturing the positive electrode 30 and the negative electrode 40, the electrode body 20 is manufactured in the manufacturing method of a secondary battery.

At this time, in the secondary battery manufacturing method, the positive electrode 30, the negative electrode 40, and the separator 50 are conveyed to the take-up roll 91.
In the secondary battery manufacturing method, the positive electrode 30, the negative electrode 40, and the separator 50 are wound by a certain amount with the separator 50 sandwiched between the positive electrode 30 and the negative electrode 40, and the positive electrode 30, the negative electrode 40, And the separator 50 is cut.
In the method for manufacturing a secondary battery, the electrode body 20 is manufactured by performing press working on such a wound positive electrode 30, negative electrode 40, and separator 50.

In the manufacture of such an electrode body 20, the positive electrode 30 and the negative electrode 40 (particularly, the part wound most inward, that is, the part wound first by the take-up roller) are wound and pressed. Bends greatly.
Therefore, each mixture layer 32 and 42 may peel from the positive electrode current collector 31 to the inner side in the width direction with the both ends in the width direction as a base point when the peel strength at the both ends in the width direction is low.
On the other hand, each of the mixture layers 32 and 42 is supported by the inner coating portions 31b and 41b from both sides in the width direction at the center portion in the width direction, so that each current collector is collected only by the binding force between particles such as an active material. The binding property with the bodies 31 and 41 can be maintained.

  Therefore, as shown in FIGS. 8 and 9, in the method for manufacturing the secondary battery according to the present embodiment, both ends are always provided between the width direction both ends of the mixture layers 32 and 42 and the current collectors 31 and 41. Application portions 31a and 41a are formed.

According to this, in the manufacturing method of the secondary battery, the application portions 31a and 41a at both ends are reliably interposed between the current collectors 31 and 41 and the mixture layers 32 and 42 in the largely bent portion. Can be made.
Therefore, the manufacturing method of the secondary battery can ensure the peel strength of the mixture layers 32 and 42 in the largely bent portion.

  For this reason, in the manufacturing method of the secondary battery, even when the current collectors 31 and 41 are largely bent when the electrode body 20 is manufactured, the both end portions in the width direction of the mixture layers 32 and 42 are used as base points. It can prevent that each mixture layer 32 * 42 peels to the width direction inner side.

  As shown in FIG. 1, after manufacturing the electrode body 20, in the secondary battery manufacturing method, the current collector terminal 61 fixed to the lid 12 and the non-mixture layers 33 and 43 of the electrode body 20 are provided. Join by ultrasonic welding.

  At this time, since the electrode body 20 is vibrated by ultrasonic waves, there is a possibility that the mixture layers 32 and 42 are peeled to the inner side in the width direction with the both ends in the width direction of the mixture layers 32 and 42 as base points. is there.

  Therefore, in the manufacturing method of the secondary battery of the present embodiment, the application portions 31a and 41a at both ends are always formed between the width direction both ends of the mixture layers 32 and 42 and the current collectors 31 and 41, respectively. The peel strength at both ends in the width direction of the mixture layers 32 and 42 is improved (see FIGS. 8 and 9).

  Thereby, the manufacturing method of a secondary battery can prevent that each mixture layer 32 * 42 peels from each current collector 31 * 41, when the electrode body 20 and the current collection terminal 61 are joined.

  After the electrode body 20 and the current collecting terminal 61 are joined, the electrode body 20 is housed in the exterior 10 in the method for manufacturing a secondary battery. And in the manufacturing method of a secondary battery, the accommodating part 11 and the cover part 12 of the exterior 10 are joined by welding.

In the method for manufacturing a secondary battery, an electrolytic solution is injected from a hole formed in the lid portion 12 to infiltrate the electrolytic solution into the electrode body 20, and the hole 10 is sealed to seal the exterior 10.
Thereafter, in the secondary battery manufacturing method, the secondary battery 1 is subjected to self-discharge inspection or the like, and the secondary battery 1 having the positive electrode 30 and the negative electrode 40 is manufactured.

  According to this, the manufacturing method of the secondary battery of the present embodiment is as follows: when the current collectors 31 and 41 are cut, when the positive electrode 30 and the negative electrode 40 are wound, when the electrode body 20 and the current collector terminal 61 are welded. The secondary battery 1 can be manufactured without the mixture layers 32 and 42 being peeled off from the current collectors 31 and 41.

  Therefore, the secondary battery manufacturing method can prevent the deterioration of the charge / discharge characteristics due to the peeling of the mixture layers 32 and 42.

As shown in FIGS. 8 and 9, in the method for manufacturing a secondary battery, a plurality of application portions 31 b and 41 b having a stripe shape in plan view are formed in the middle portions in the width direction of the mixture layers 32 and 42. .
According to this, the manufacturing method of a secondary battery can form each mixture layer 32 * 42 directly on each collector 31 * 41 in the area | region in which each non-application part 31c * 41c is formed.

  Therefore, the secondary battery manufacturing method can suppress an increase in the electrical resistance of the secondary battery 1 as compared with the case where the coating portion is formed in the entire region where the mixture layers 32 and 42 are formed.

  In other words, in the method of manufacturing a secondary battery, in each mixture layer 32 and 42, both end portions in the width direction where a relatively high peel strength is required are always adhered by the application portions 31a and 41a at both ends to ensure the peel strength. In addition, the intermediate portion in the width direction where a relatively high peel strength is not required is partially adhered by the inner application portions 31b and 41b to ensure conductivity.

According to this, the manufacturing method of the secondary battery can optimize the balance between the peeling strength and the conductivity of the mixture layers 32 and 42.
Therefore, the method for producing a secondary battery can both suppress an increase in electrical resistance and improve the peel strength.

In this way, in the method of manufacturing the secondary battery, in the step of forming the application portions 31a, 31b, 41a, and 41b, the binder liquid A is applied to the regions corresponding to both ends in the width direction of the mixture layers 32 and 42. It coats continuously and forms application part 31a * 41a of the both ends which continue in the length direction of each mixture layer 32 * 42.
Further, in the step of forming the application portions 31a, 31b, 41a, and 41b, the binder liquid A is partially applied to the inner regions of the mixture layers 32 and 42 in the width direction at both ends, and the inner application is performed. The portions 31b and 41b are formed, and the non-application portions 31c and 41c are formed as regions where the inner application portions 31b and 41b are not formed.

  The manufacturing method of the secondary battery is such that the application portions 31a and 41a at both ends are always formed in the regions where the width direction both ends of the mixture layers 32 and 42 are formed, and each mixture is formed by the application portions 31a and 41a at both ends. The powder B can be reliably adhered to both ends in the width direction of the layers 32 and 42.

According to this, the manufacturing method of the secondary battery can stabilize the positions of both end portions in the width direction of the mixture layers 32 and 42 (positions of the outer edge portions of the mixture layers 32 and 42 in the width direction). .
Therefore, the manufacturing method of the secondary battery can improve the accuracy of the widths of the non-mixture layers 33 and 43.

Therefore, the manufacturing method of the secondary battery can make each mixture layer 32 and 42 oppose correctly when manufacturing the electrode body 20 (refer FIG. 2).
That is, the secondary battery manufacturing method can accurately match the positions of both end portions in the width direction of the mixture layers 32 and 42 facing each other with the separator 50 interposed therebetween. That is, the method for manufacturing a secondary battery makes it difficult for the end portion of one mixture layer to protrude in the width direction with respect to the end portion of the other mixture layer, thereby eliminating unevenness in battery reaction.

  For this reason, the manufacturing method of a secondary battery can improve battery performance.

  Here, in the manufacturing method of the secondary battery according to the present embodiment, the application portions 31 a, 31 b, 41 a, and 41 b are formed in a stripe shape in plan view along the length direction of the current collectors 31 and 41.

According to this, when manufacturing the electrode body 20, the manufacturing method of the secondary battery is such that each current collector 31, 41 and each mixture layer 32. All the application parts 31a, 31b, 41a, and 41b can be interposed between 42.
In other words, the method for manufacturing a secondary battery has a higher peel strength at the greatly bent portion than when the application portions are formed in a stripe shape in plan view along the width direction of the current collectors 31 and 41. It can be improved.

  Therefore, the method for manufacturing the secondary battery can more reliably prevent the mixture layers 32 and 42 from being peeled even when the current collectors 31 and 41 are largely bent when the electrode body 20 is manufactured. Can be prevented.

Here, as shown in FIG. 16, when forming a substantially lattice-shaped coating portion in plan view, the blade 74 contacts the outer peripheral surface of the gravure roll 172 while straddling the groove 172 a of the gravure roll 172. .
In this case, when the blade 74 contacts the outer peripheral surface of the gravure roll 172 across the groove 172a, the blade 74 imparts a shearing force to the binder liquid A that has entered the groove 172a.
The binder liquid A that has entered the groove 172a is lifted to the outer peripheral surface of the gravure roll 172 by the shearing force (see the arrow in the vicinity of the binder liquid A in FIG. 16).

Therefore, in this case, there is a possibility that the binder liquid A cannot be accurately transferred along the shape of the groove 172a.
That is, in this case, there is a possibility that the application portion having a substantially lattice shape in plan view cannot be formed accurately.

On the other hand, in the manufacturing method of the secondary battery of the present embodiment, the application portions 31a, 31b, 41a, and 41b are formed in a stripe shape in plan view along the length direction of the current collectors 31 and 41.
For this reason, as shown in FIGS. 3 and 4, in the gravure roll 72, the shape of each of the groove portions 72 a and 72 b is a shape along the circumferential direction of the gravure roll 72, that is, the rotational direction.

Therefore, in the method for manufacturing a secondary battery, the blade 74 does not straddle the grooves 72a and 72b.
For this reason, in the method for manufacturing a secondary battery, the binder liquid A that has entered the groove 172a is lifted to the outer peripheral surface of the gravure roll 172, as in the case of forming a substantially lattice-shaped coating portion in plan view. Can be prevented.

Therefore, the secondary battery manufacturing method can accurately transfer the binder liquid A to the surfaces of the current collectors 31 and 41. That is, the manufacturing method of the secondary battery can apply the binder liquid A according to the pattern.
For this reason, the method for manufacturing a secondary battery can more reliably achieve both an increase in electrical resistance and an improvement in peel strength.

  As described above, in the method of manufacturing the secondary battery, in the step of forming the coating portions 31a, 31b, 41a, and 41b, the striped coating portions 31a and 31b along the length direction of the mixture layers 32 and 42 are formed. -41a and 41b are formed.

As described above, in the manufacturing method of the secondary battery, the widths of the coating portions 31a and 41a at both ends are made longer than the widths of the inner coating portions 31b and 41b (see widths D1 and D2 shown in FIG. 5).
Thereby, in the manufacturing method of a secondary battery, the peeling strength of the width direction both ends of each mixture layer 32 * 42 is made higher.

  According to this, the manufacturing method of a secondary battery can ensure more reliably the peeling strength of the width direction both ends of each mixture layer 32 * 42, and it is the electroconductivity in the width direction middle part of each mixture layer 32 * 42. Can be secured.

That is, the manufacturing method of the secondary battery can make the balance between the peel strength and the conductivity of each mixture layer 32 and 42 more optimal.
Therefore, the method for manufacturing a secondary battery can more reliably achieve both suppression of an increase in electrical resistance and improvement of peel strength.

  Thus, in the manufacturing method of the secondary battery, the widths of the application portions 31a and 41a at both ends formed in the regions corresponding to the both ends in the width direction of the mixture layers 32 and 42 are the same as those of the mixture layers 32 and 42. It is longer than the width of the inner coating portions 31b and 41b formed in the inner region from both ends in the width direction.

  Next, the result of measuring the peel strength of the negative electrode mixture layer 42 will be described.

  As shown in FIG. 11, in the measurement, the peel strength at both ends in the width direction of the negative electrode mixture layer 42 (see reference symbol P <b> 1 shown in FIG. 11) and the peel strength at the middle portion in the width direction of the negative electrode mixture layer 42 (FIG. 11). ) (See reference P2).

In the measurement, after forming the negative electrode mixture layer 42 on the negative electrode current collector 41, a cut was made along the width direction of the negative electrode current collector 41 between the negative electrode current collector 41 and the negative electrode mixture layer 42. The negative electrode mixture layer 42 was peeled off from the negative electrode current collector 41 along the length direction of the electric body 41.
In the measurement, the peel strength of the negative electrode mixture layer 42 of the present embodiment was measured by measuring the magnitude of the force required at this time.

  As shown in FIG. 12 and FIG. 17, in the measurement, as a comparative example, an application part having a lattice shape in plan view was formed on the negative electrode current collector, and the peel strength at both ends in the width direction of the negative electrode mixture layer (shown in FIG. 17). The reference symbol P3) and the peel strength at the intermediate portion in the width direction of the negative electrode mixture layer (see reference symbol P4 shown in FIG. 17) were measured.

  The peel strength of the negative electrode mixture layer of the comparative example was higher in the peel strength in the middle in the width direction than the peel strength at both ends in the width direction.

This is considered to be due to the formation of non-coated portions, which are portions where the binder liquid is not applied, at both ends in the width direction of the negative electrode mixture layer.
That is, in this case, the negative electrode mixture layer is bound only by the binding force between the particles of the negative electrode active material or the like in the portion where the non-coated portion is formed, and as a result, the non-coated portion is formed. It is thought that the peel strength at the part where the film is lowered.

  On the other hand, as shown in FIG. 11 and FIG. 12, the peel strength at both ends in the width direction of the negative electrode mixture layer 42 of the present embodiment is the peel strength at the intermediate portion in the width direction of the present embodiment and the negative electrode mixture of the comparative example. It became higher than the peel strength at both ends in the width direction of the layer.

This is considered to be due to the presence of the coating portions 41 a at both ends at both ends in the width direction of the negative electrode mixture layer 42.
That is, in this case, the negative electrode current collector 41 and the negative electrode mixture layer 42 can be bound with a strong force at the both ends in the width direction of the negative electrode mixture layer 42 by the binding force of the coating portions 41a at both ends.
Therefore, in this case, it is considered that the negative electrode mixture layer 42 did not peel until a large force was applied to the negative electrode mixture layer 42.

  As described above, in the method for manufacturing a secondary battery, the application portions 31a at both ends continuous in the length direction of the mixture layers 32 and 42 are formed in regions corresponding to both ends of the mixture layers 32 and 42 in the width direction. -It turns out that the peeling strength in the width direction both ends of each mixture layer 32 * 42 can be improved by forming 41a.

  Next, the result of measuring the width of the negative electrode non-mixture layer 43 will be described.

As shown in FIG. 13, in the measurement, as Comparative Example 1, a negative electrode mixture layer was formed after forming a planar grid-like coating portion on the negative electrode current collector, and the width of the negative electrode non-mixture layer was measured. .
In the measurement, as Comparative Example 2, a negative electrode mixture layer was formed after forming a dot-like coated portion in plan view on the negative electrode current collector, and the width of the negative electrode non-mixture layer was measured.

In FIG. 13, “◯” is described in the column of the width of the non-mixture layer when the variation in the width of the negative electrode mixture layer is small.
In FIG. 13, “x” is described in the column of the width of the non-mixture layer when the variation in the width of the negative electrode mixture layer is large.

In the negative electrode non-mixture layers of Comparative Example 1 and Comparative Example 2, the measurement result of the width was “x”.
This is because the presence of the region where the coating part is not formed at both ends in the width direction of the negative electrode mixture layer, the powder cannot be reliably adhered to the region, and as a result, the negative electrode non-mixture layer It is thought that the width of the has varied.

On the other hand, in the negative electrode non-mixture layer 43 of this embodiment, the measurement result of the width was “◯”.
This is because the application part 41a at both ends is always present at both ends in the width direction of the negative electrode mixture layer 42, so that the powder B can be reliably attached to both ends in the width direction of the negative electrode mixture layer 42. It is considered that the variation in the width of the negative electrode non-mixture layer 43 is reduced.

  As described above, in the method for manufacturing a secondary battery, the application portions 31a at both ends continuous in the length direction of the mixture layers 32 and 42 are formed in regions corresponding to both ends of the mixture layers 32 and 42 in the width direction. -It turns out that the dispersion | variation in the width | variety of each non-mixture layer 33 * 43 can be reduced by forming 41a.

In addition, the manufacturing method of a secondary battery should just form application | coating of both ends in the width direction both ends of each mixture layer, and it is not necessarily the striped application part of planar view along the length direction of each mixture layer There is no need to form.
For example, as shown in FIG. 14, in the method for manufacturing a secondary battery, as an inner application part formed on the positive electrode current collector 31, for example, a planar grid application part 131 b and a planar dot application part 231 b are used. Alternatively, the application portion 331b may be formed with a diagonal line in plan view.

  If the application part 331b that is oblique in plan view is formed, the inclination angle of the application part 331b with respect to the length direction of the positive electrode current collector 31 is preferably 45 ° or less.

Thereby, the manufacturing method of the secondary battery is a gravure roll, even when a shearing force is applied to the binder liquid infiltrated into the groove of the gravure roll when the binder liquid adhered to the outer peripheral surface of the gravure roll is scraped off by the blade. The binder liquid that has entered the groove portion can escape along the shape of the groove portion.
Therefore, the manufacturing method of the secondary battery can accurately form the application portion 331b that is oblique in plan view.

In addition, in the case of forming the application part 131b having a lattice shape in plan view, the application part 231b having a dot shape in plan view, or the application part 331b having a diagonal line in plan view as illustrated in FIG. You may make the width | variety of the application part 31a of both ends longer than the width | variety of each application part 131b * 231b * 331b.
Thereby, since the manufacturing method of a secondary battery can make the balance of the peeling strength of a mixture layer and electroconductivity more optimal, it suppresses the increase in electrical resistance and improves peeling strength. This can be achieved more reliably.

In addition, the kind of electrode body manufactured by the manufacturing method of a secondary battery is not limited to this embodiment.
For example, as shown in FIG. 15, the secondary battery manufacturing method may manufacture an electrode body 420 in which a substantially plate-like positive electrode 430 and negative electrode 440 are stacked in the thickness direction with a separator 450 interposed therebetween.
In this case, the direction in which one end is adjacent to the positive electrode mixture layer 433 and the other end is the end of the positive electrode current collector 431, that is, the horizontal direction in FIG. It becomes the width direction of the mixture layer concerning. Further, in this case, the direction perpendicular to the width direction of the mixture layer and the thickness direction of the positive electrode current collector 430, that is, the vertical direction on the paper surface in FIG. 15, is the length direction of the mixture layer according to the present invention. Become.

DESCRIPTION OF SYMBOLS 1 Secondary battery 30 Positive electrode 31a * 31b Application part 31c Non-application part 32 Positive electrode mixture layer 40 Negative electrode 41a * 41b Application part 41c Non-application part 42 Negative electrode mixture layer A Binder liquid B Powder

Claims (3)

A method for producing a secondary battery having a positive electrode and a negative electrode in which a mixture layer is formed on the surface of a current collector,
Forming a coating portion by applying a binder pattern on the surface of the current collector; and
Supplying powder containing mixture particles on the surface of the current collector and the binder to form the mixture layer;
To produce at least one of the positive electrode and the negative electrode,
In the step of forming the application part,
In the region corresponding to both ends in the width direction of the mixture layer, the binder is continuously applied to form the application portion continuous in the length direction of the mixture layer,
The region inside the both widthwise end portions of the mixture layer, thereby forming the coating portion of the binder by partially coating, which forms a non-coating portion as said coating portion is not formed region And
The powder includes, as the mixture particles, active material particles, conductive particles, and a powdery binder, or active material particles, conductive particles, and granulated particles including a binder, or the powder The body includes, as the mixture particles, active material particles, conductive particles, and a powdery binder, and a mixture of active material particles, conductive particles, and granulated particles containing the binder,
In the step of forming the mixture layer, the supplied powder is compressed.
A method for manufacturing a secondary battery. In the step of forming the application part,
The binder is pattern-coated continuously in the length direction of the mixture layer while being spaced apart in the width direction of the mixture layer, and the striped application part along the length direction of the mixture layer Form,
The manufacturing method of the secondary battery of Claim 1. The width of the application part formed in the region corresponding to both ends in the width direction of the mixture layer,
Longer than the width of the application part to be formed in the region inside the width direction both ends of the mixture layer,
The manufacturing method of the secondary battery of Claim 1 or Claim 2.

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