KR20200141859A - Electrode-assembly and manufacturing method thereof - Google Patents

Abstract

Provided is a method for manufacturing an electrode assembly according to the present invention, in which a plurality of unit cells are placed one by one on a folding separator, and the folding separator is folded from one side to the other side so that the unit cells are stacked. The method comprises the steps of: (S1) manufacturing an electrode by applying an active material to the surface of a current collector; (S2) manufacturing unit cells by stacking a predetermined number of positive electrodes, separators, and negative electrodes; (S3) placing the unit cells on the folding separator; and (S4) folding the folding separator so that the unit cells are stacked, in which an adhesive layer is coated on the electrode placed on the outermost layer in the step of manufacturing an electrode (S1). In the electrode assembly according to the present invention in which a plurality of unit cells are placed one by one on the folding separator and the folding separator is folded from one side to the other side so that the unit cells are stacked, the outermost unit cells located in the uppermost and lowermost layers among the unit cells are coated with an adhesive layer having adhesive force on the outermost layer facing the folding separator.

Description

Electrode-assembly and manufacturing method thereof TECHNICAL FIELD

The present invention relates to an electrode assembly and a manufacturing method thereof, which are manufactured by being stacked by folding from one side of the folding separator after unit cells are seated on a folding separator, and more specifically, to the outermost of the unit cells located at the outermost side. The present invention relates to an electrode assembly and a method of manufacturing the same, in which an adhesive layer is disposed between an electrode of each layer and a folding separator so that the appearance of an electrode assembly, that is, a wrinkle in the surface of the folding separator, can be solved.

Batteries that store electrical energy may generally be classified into primary batteries and secondary batteries. While the primary battery is a disposable consumable battery, the secondary battery is a rechargeable battery manufactured using a material capable of repeating oxidation and reduction processes between current and material. That is, when a reduction reaction is performed on a material by electric current, power is charged, and when an oxidation reaction is performed on the material, the power is discharged. As such, electricity is generated by repetitive charge-discharge.

In general, types of secondary batteries include nickel cadmium batteries, nickel hydride batteries, lithium ion batteries, and lithium ion polymer batteries. Such secondary batteries have been applied and used not only for small products, but also for large products requiring high output, power storage devices for storing surplus generated power or new renewable energy, and power storage devices for backup.

Of these, a lithium secondary battery is generally formed by stacking a cathode, a separator, and an anode. And these materials are selected in consideration of battery life, charge/discharge capacity, temperature characteristics and stability. As the process of intercalation and deintercalation of lithium ions from the lithium metal oxide of the positive electrode to the negative electrode is repeated, charging and discharging of the lithium secondary battery proceeds.

In general, unit cells stacked in a three-layer structure of an anode/separator/cathode, or a five-layer structure of anode/separator/cathode/separator/anode or cathode/separator/anode/separator/cathode, or anode/separator/cathode It is repeatedly stacked to form one electrode assembly. And such an electrode assembly is accommodated in a case such as a cylindrical can or a square pouch.

Meanwhile, the electrode assembly is typically manufactured in a winding type (jelly roll type), a stack type (stack type), a stack and folding type, and the like.

The double stack and folding type has a mixed form of the winding type and the stack type. In other words, as shown in Fig. 1A, which shows how the electrode assembly is manufactured by the stack and folding method, a full cell or cathode (anode)/separator/anode (cathode )/Separator/cathode (anode) structure bicell (bicell), the unit cells 20 are placed on the folding separator 10 and successively folded (folded). . This stack-and-folding type electrode assembly has high stability because movement is additionally supported by the folding separator 10.

On the other hand, secondary batteries are manufactured to have various shapes and sizes according to their intended use. For example, secondary batteries used in tablet PCs and the like are manufactured to have a thin thickness but a relatively large area.

However, in the case of manufacturing a large-area electrode assembly in a stack-and-folding method, there is a problem that wrinkles occur on the surface of the folding separator 10. That is, as shown in FIG. 1B, where a wrinkle occurs on the surface of the pouch 40 in which the electrode assembly is embedded, the unit placed at the outermost side of the folding separator 10 while the folding separator 10 is being folded. There is a problem that wrinkles occur because complete adhesion and fixation are not achieved between cells. In addition, such wrinkles become more severe when heat and pressure are applied in an electrolyte injection process, a degas process, etc. after the electrode assembly is inserted into a pouch or case, thereby causing wrinkles on the appearance of the pouch 40.

Accordingly, the present invention is an electrode assembly manufactured by folding the folding separator after a plurality of unit cells are seated on the folding separator, and the folding separator and the outermost unit cell placed at the outermost side are adhered to each other, thereby effectively generating wrinkles. The main purpose is to provide an electrode assembly and a method of manufacturing the same that can suppress

The present invention for achieving the object as described above provides a method of manufacturing an electrode assembly capable of suppressing the occurrence of wrinkles, and an electrode assembly capable of being manufactured by the above manufacturing method.

The electrode assembly according to the present invention is an electrode assembly manufactured by placing a plurality of unit cells on a folding separator one by one and folding the folding separator from one side to the other so that stacking of the unit cells is achieved, and the uppermost layer of the unit cells and The outermost unit cells located in the lowermost layer are characterized in that an adhesive layer having adhesive strength is coated on the outermost layer facing the folding separator.

On the outermost layer facing the folding separator in the outermost unit cell, a single-sided electrode coated with an active material is disposed on only one surface of the current collector, and the adhesive layer is coated on the surface of the current collector on which the active material is not applied in the single-sided electrode.

The adhesive layer may be formed by curing after a coating solution having adhesive strength is applied to the surface of the current collector.

In this case, the coating solution may contain a binder polymer, and an organic material or an inorganic material may be additionally added to the binder polymer.

Alternatively, the adhesive layer may be formed by laminating a film having adhesive force on the surface of the current collector.

In addition, the manufacturing method according to the present invention is a method of manufacturing an electrode assembly manufactured by placing a plurality of unit cells on a folding separator one by one and folding the folding separator from one side to the other so that the unit cells are stacked. An electrode manufacturing step (S1) of preparing a positive electrode and a negative electrode, respectively, by coating an active material on the surface of the; Manufacturing unit cells by stacking an anode, a separator, and a cathode by a predetermined number (S2); Seating the unit cells on a folding separator (S3); And folding the folding separator so that the unit cells are stacked (S4), and when folding is performed, among electrodes (anode and cathode) stacked on the outermost unit cells placed on the outermost layer, The electrode placed on the outermost layer is a single-sided electrode on which the active material is placed only on one side of the current collector, and the single-sided electrode is coated with an adhesive layer on the other side in the electrode manufacturing step (S1), and the step of seating the unit cells on the folding separator ( In S3), the single-sided electrode is mounted to be adhered to the folding separator through an adhesive layer.

In addition, the adhesive layer may be coated by applying a coating solution having adhesiveness to the current collector surface of the single-sided electrode and then curing to form the adhesive layer.

In this case, the coating liquid may be applied thicker in a specific area than in other areas on the current collector surface of the single-sided electrode that comes into contact with the folding separator.

The adhesive layer may be attached to a film in place of the coating solution. That is, the coating of the adhesive layer may form an adhesive layer by laminating a film having adhesiveness on the current collector surface of the single-sided electrode.

In the present invention having the above-described configuration, the adhesion between the electrode placed on the outermost layer of the outermost unit cells and the folding separator is made by the adhesive layer, so that the occurrence of wrinkles can be suppressed.

In addition, since the adhesive layer is applied to the outermost unit cells, it is possible to accurately form the adhesive layer only in a region where the electrode and the folding separator contact each other than when coated on the folding separator. Accordingly, waste of the coating liquid or the adhesive film can be prevented, and an adhesive layer can be formed regardless of the thickness or shape of the folding separator.

Therefore, the electrode assembly and its manufacturing method according to the present invention can minimize the occurrence of defects because wrinkles are suppressed in the appearance of the folding separator.

1A is a view showing a state in which unit cells are seated side by side on a folding separator and then folded from one side to form an electrode assembly.
1B is a view showing the appearance of wrinkles on the surface of an electrode assembly manufactured according to a conventional method.
Figure 2 is a flow chart showing the steps according to the manufacturing method of the present invention.
3 is a view showing a state in which the unit cells are seated on the folding separator, and an adhesive layer is additionally coated on the outermost electrode (anode) in contact with the folding separator in the outermost unit cells placed on the outermost layer.
4 is a view showing a state in which the thickness of the adhesive layers coated on the outermost electrodes placed on the outermost layer are formed differently.
5 is a view showing a state of being manufactured as an electrode assembly by folding in the state of FIG. 3.
6 is a diagram showing a graph and a table showing the adhesion between the folding separator and the outermost unit cell when the adhesive layer is not formed and the adhesion between the folding separator and the outermost unit cell when the adhesive layer is formed.
7 is a view showing a comparison of a state in which an electrode assembly having a conventional structure without an adhesive layer is inserted into a pouch (left) and a state in which an electrode assembly with an adhesive layer formed according to the present invention is inserted into a pouch (right).

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

In order to clearly describe the present invention, parts irrelevant to the description have been omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

In addition, terms or words used in the present specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor appropriately defines the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

The present invention relates to an electrode assembly and a method of manufacturing the same, which can effectively suppress the occurrence of wrinkles by adhesion between the folding separator 10 and the outermost unit cell 20b placed on the outermost shell. Embodiments according to the present invention will be described in more detail with reference to these.

Embodiment 1

In the present invention, a plurality of unit cells 20 (20a, 20b, 20c) are placed on the folding separator 10, and the folding separator 10 is disposed from one side to the other so that the unit cells 20 are stacked. A method of manufacturing an electrode assembly manufactured by folding is provided as a first embodiment.

Figure 2 is a flow chart showing the steps according to the manufacturing method of the present invention, Figure 3 is a folding in the outermost unit cells (20b) to be placed on the outermost layer while the unit cells 20 are seated on the folding separator 10 It is a view showing a state in which the adhesive layer 30 is additionally coated on the outermost electrode that comes into contact with the separator 10.

2 and 3, in this embodiment, an electrode manufacturing step (S1) of manufacturing an electrode (ie, a positive electrode and a negative electrode) by coating an active material on the surface of a current collector, and manufacturing the unit cells 20 (S2), mounting the unit cells 20 (S3), and folding the folding separator 10 (S4). At this time, in the electrode manufacturing step (S1), all other electrodes are manufactured as double-sided electrodes in which the active material is applied to both sides of the current collector, but the electrode to be coated with the adhesive layer is manufactured as a single-sided electrode. In the example, it is made with a single-sided anode).

In the electrode manufacturing step (S1), an active material is applied to one side or both sides of a current collector, thereby manufacturing a double-sided electrode and a single-sided electrode to be coated with an adhesive layer. That is, the positive electrode 21 is manufactured by coating a positive electrode active material on the surface of the positive electrode current collector, and the negative electrode is manufactured by coating a negative electrode active material on the surface of the negative electrode current collector. At this time, in this embodiment, an adhesive layer is coated on the single-sided anode. Accordingly, the single-sided anode is manufactured such that a positive electrode active material is coated on one side of the positive electrode current collector and an adhesive layer is coated on the other side.

And, in the step (S2) of manufacturing the unit cells 20, the anode 21, the separator 23, and the cathode 22 are stacked by a predetermined number to form the unit cells 20: 20a, 20b, 20c. To manufacture. In this step, the unit cells 20 are C-type bi-cells 20c stacked in the order of the cathode 22 / separator 23 / anode 21 / separator 23 / cathode 22 from top to bottom. And an A-type bi-cell 20a having a structure of an anode 21/separator 23/cathode 22/separator 23/anode 21.

And, in the unit cell manufacturing step (S2), when folding of the folding separator 10 of the C-type bi-cell 20c and A-type bi-cell 20a is completed, unit cells disposed at the outermost side ( Hereinafter, the outermost unit cell) of the outermost layer of the 20b, a region placed on the outermost side of the folding separator 10 (i.e., the opposite side of the region placed from the folding separator to the outer surface when folding is completed as shown in FIG. It is manufactured so that a single-sided electrode is placed on the outermost layer to be in contact with

Meanwhile, in this embodiment, the electrode stacked on the outermost unit cells 20b and placed on the outermost layer in the electrode manufacturing step S1 is a single-sided electrode in which an active material is coated only on one surface of the current collector. The single-sided electrode is configured such that the current collector is exposed to the outside on the surface where the active material is not applied (although it may be a single-sided cathode), and in this embodiment, it is composed of a single-sided anode 21a. Accordingly, the cross-sectional anode 21a is disposed such that the layer on which the active material is applied faces the separator 23 and the surface where the active material is not applied and the current collector is exposed faces the folding separator 10.

In addition, the adhesive layer 30 may be coated in the step of manufacturing the unit cell (S2), but it is preferable to be coated in the electrode manufacturing step (S1) for convenience of the manufacturing process. The adhesive layer 30 is coated on the surface of the current collector to which the active material is not applied in the single-sided anode 21a.

In the method of coating the adhesive layer 30, the coating of the adhesive layer 30 may be performed by various known methods, but in this embodiment, a method of applying a coating liquid and a method of attaching an adhesive film are provided.

First, in the method of forming the adhesive layer 30 by applying the coating liquid, a coating liquid that creates adhesion by applying an attractive force between molecules on the applied surface is applied in a liquid state, and then between the cross-section anode 21a and the folding separator 10 It is configured to cure.

At this time, the coating solution may be a known coating solution that can be used when manufacturing a secondary battery. For example, it may contain a binder polymer, and an organic material or an inorganic material may be additionally added to the binder polymer.

In addition, as shown in FIG. 4 showing a state in which the thicknesses of the adhesive layers 30 coated on the outermost unit cells 20b placed on the outermost layer are formed differently, the coating amount of the coating solution may be adjusted in thickness. have. That is, depending on the design of the electrode assembly or the characteristics of the coating solution, the coating amount of the uppermost layer and the lowermost layer may vary.

In addition, the adhesive layer 30 may be formed by laminating a film having adhesive force on the surface of the current collector instead of the coating solution.

And, in the step (S3) of seating the unit cells 20 on the folding separator 10, the folding separator 10 is folded in the state of FIG. 3 to be manufactured as an electrode assembly. As shown, when folding is completed, the A-type bicells 20a so that the cathode 22 and the anode 21 have an alternately repeated structure with the separator 23 or the folding separator 10 interposed therebetween. And C-type bi-cells 20c are respectively seated in predetermined positions. At this time, the outermost bi-cells 20b on which the adhesive layer 30 is formed are disposed so that when folding is performed, each of them is placed on the top and bottom layers, and the adhesive layer 30 of them is placed on the outermost side ( That is, when folding is complete, the bicell placed on the top layer is placed on the upper side, and the bicell placed on the bottom layer is placed so that the adhesive layer is placed on the bottom).

In the present invention, since the adhesive layer 30 is formed on the outermost bi-cell 20b placed on the outermost side, the use of the adhesive can be reduced compared to when the adhesive is applied to the folding separator 10, and the adhesive layer 30 is formed of the folding separator 10 ), it is possible to prevent the impregnation performance from deteriorating when the electrode assembly is embedded in the pouch 40 and impregnated with the electrolyte.

Finally, when the step (S4) of folding the folding separator 10 so that the unit cells 20 are stacked is completed, the manufacturing of the electrode assembly having the stack-and-fold structure is completed.

6 shows a graph and a table showing the adhesion between the folding separator and the outermost unit cell when the adhesive layer is not formed; and the adhesion between the folding separator and the outermost unit cell when the adhesive layer is formed. As described above, the electrode assembly of the present invention in which the adhesive layer 30 is additionally formed on the outermost unit cell (by cell) is formed between the outermost cross-section anode 21a and the folding separator 10 by the adhesive layer 30. It can be seen through Figure 6 that the adhesive strength is increased.

That is, the graph and table shown in FIG. 6 are placed on the outermost layer of the electrode assembly manufactured according to the present invention and the force required when peeling off the end portion of the folding separator 10 adhered by the adhesive layer 30 ( Adhesion) is the result of a peel test measuring. The test is a measurement of the force required when holding the end of the folding separator 10 and peeling it off at a speed of 50 mm/min in the vertical 90° direction.

As shown in Figure 6, it can be seen that the adhesive strength increased in the case of the adhesive layer 30 in both the dry state (before the electrolytic solution impregnation process) as well as the wet state (after the electrolytic solution impregnation process) compared to the case without the adhesive layer.

That is, conventional wrinkles are generated by the lifting between the folding separator 10 and the outermost unit cell 20b, and therefore, between the folding separator 10 and the outermost unit cell 20b by the adhesive layer 30 Increasing the adhesion can suppress the occurrence of wrinkles.

FIG. 7 shows a comparison of a state in which an electrode assembly of a conventional structure in which the adhesive layer 30 is not formed is inserted into a pouch (left) and an electrode assembly with an adhesive layer 30 formed according to the present invention inserted into the pouch (right). It is a drawing. As shown, it can be seen that when the electrode assembly manufactured by the manufacturing method of the present invention is embedded in the pouch, unlike the electrode assembly of the conventional structure, wrinkles do not occur on the exterior.

Embodiment 2

The present invention provides an electrode assembly that can be manufactured by the manufacturing method according to the first embodiment as a second embodiment.

In this embodiment, as shown in FIG. 5, in the electrode assembly, a plurality of unit cells 20 (20a, 20b, 20c) are placed on the folding separator 10 one by one, and the stacking of the unit cells 20 is The folding separator 10 has a structure in which the folding separator 10 is folded from one side to the other to be stacked. At this time, the anode 21 and the cathode 20 are repeatedly stacked, and the separator 23 or the folding separator 10 is positioned between the anode 21 and the cathode 22.

In addition, the outermost unit cells 20b positioned at the uppermost layer and the lowermost layer among the unit cells are coated with an adhesive layer 30 having adhesive force on the outermost layer facing the folding separator 10.

At this time, the electrode placed on the outermost layer facing the folding separator 10 in the outermost unit cell 20b is a single-sided electrode in which an active material is applied only to one surface of the current collector, and the adhesive layer 30 is applied to the surface where the active material is not applied. It is coated.

The adhesive layer 30 may be formed by applying a coating liquid having adhesive force on the surface of a current collector and then curing, or may be formed by laminating a film having adhesive force.

In the present invention having the configuration as described above, the adhesion between the single-sided electrode placed on the outermost side of the outermost unit cells 20b and the folding separator 10 is made by the adhesive layer 30, so that the occurrence of wrinkles can be suppressed. .

In addition, since the adhesive layer 30 is coated on the outermost unit cells, the adhesive layer can be accurately formed only in the area where the electrode and the folding separator contact each other than when it is coated on the folding separator 10, thereby reducing waste of coating liquid or adhesive film. Can be prevented. Accordingly, an adhesive layer can be formed regardless of the thickness or shape of the folding separator 10.

Therefore, the electrode assembly and its manufacturing method according to the present invention can minimize the occurrence of defects since wrinkles are suppressed in the appearance of the folding separator.

In the above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited thereto, and the technical idea of the present invention and the following description by those of ordinary skill in the art to which the present invention pertains. Various implementations are possible within the equal range of the claims to be made.

10: folding separator
20: unit cell (20a: A type bi-cell, 20c: C type bi-cell, 20b: outermost bi-cell)
21: anode, 21a: single-sided anode
22: cathode
23: separator
30: adhesive layer
40: pouch

Claims (11)

In the electrode assembly manufactured by folding the folding separator from one side to the other so that a plurality of unit cells are placed one by one on the folding separator and the unit cells are stacked,
An electrode assembly, characterized in that the outermost unit cells positioned at the uppermost layer and the lowermost layer among the unit cells are coated with an adhesive layer having adhesive force on the outermost layer facing the folding separator.
The method of claim 1,
In the outermost layer facing the folding separator in the outermost unit cell, a single-sided electrode coated with an active material is disposed on only one surface of a current collector, and the adhesive layer is coated on the surface of a current collector uncoated with an active material in the single-sided electrode. Electrode assembly characterized by.
The method of claim 2,
The adhesive layer is an electrode assembly, characterized in that formed by curing after applying a coating solution having adhesive force on the surface of the current collector.
The method of claim 3,
The coating liquid is an electrode assembly, characterized in that the binder (binder) causing a bonding force to the surface of the current collector.
The method of claim 4,
The coating solution is an electrode assembly, characterized in that prepared by adding an organic material to a binder.
The method of claim 4,
The coating solution is an electrode assembly, characterized in that prepared by adding an inorganic material to a binder.
The method of claim 2,
The adhesive layer is an electrode assembly, characterized in that formed by laminating a film having adhesive force on the surface of the current collector.
In the method of manufacturing an electrode assembly manufactured by placing a plurality of unit cells on a folding separator one by one and folding the folding separator from one side to the other so that the unit cells are stacked,
An electrode manufacturing step (S1) of manufacturing a positive electrode and a negative electrode, respectively, by coating an active material on the surface of the current collector;
Manufacturing unit cells by stacking an anode, a separator, and a cathode by a predetermined number (S2);
Seating the unit cells on a folding separator (S3); And
Including; folding the folding separator so that the unit cells are stacked (S4);
When folding is performed, among the electrodes stacked on the outermost unit cells placed on the outermost layer, the outermost electrode is a single-sided electrode in which an active material is placed only on one side of the current collector, and the single-sided electrode is the electrode manufacturing step ( In S1), an adhesive layer is coated on the other side,
In the step (S3) of seating the unit cells in the folding separator, the single-sided electrode is seated to be adhered to the folding separator through an adhesive layer.
The method of claim 8,
The coating of the adhesive layer,
A method of manufacturing an electrode assembly, characterized in that an adhesive layer is formed by applying a coating liquid having adhesiveness on the surface of a current collector of a single-sided electrode and then curing it.
The method of claim 9,
The method of manufacturing an electrode assembly, wherein the coating solution is applied thicker in a specific area than in other areas on the surface of the current collector of the single-sided electrode in contact with the folding separator.
The method of claim 8,
The coating of the adhesive layer,
The outermost unit cell is a method of manufacturing an electrode assembly, characterized in that the adhesive layer is formed by laminating a film having adhesive properties on the current collector surface of the single-sided electrode.

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