KR20160059688A - Electrode assembly - Google Patents

Abstract

The present invention relates to an electrode assembly and, more particularly, to an electrode assembly which maximizes capacity of a secondary battery and improves stability while improving the appearance of the secondary battery. The electrode assembly according to the present invention comprises: a unit stacking part having a structure of alternately stacking a plurality of electrodes and separation membranes; and a polymer film part arranged to contact the outside surface of the outermost electrode of the unit stacking part. The size of the polymer film part is either equal to the size of the outermost electrode or greater than the size of the outermost electrode.

Description

ELECTRODE ASSEMBLY

The present invention relates to an electrode assembly, and more particularly, to an electrode assembly capable of maximizing a capacity of a secondary battery, improving safety, and improving the appearance of the secondary battery.

Unlike primary batteries, rechargeable secondary batteries can be recharged, and they are being researched and developed recently due to their small size and high capacity. As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing.

The secondary battery may be configured such that an electrode assembly is embedded in the battery case. The electrode assembly mounted inside the battery case is a charge / dischargeable power generating device formed of a stacked structure of a positive electrode / separator / negative electrode.

1 is an exploded perspective view showing a structure in which a conventional electrode assembly is embedded in a case of a secondary battery. 2 is a perspective view showing a state in which the secondary battery is assembled in the drawing of FIG.

1 and 2, the electrode assembly 30 is formed by alternately stacking a plurality of electrodes 31 and a separation membrane 33. An electrode tab 51 is connected to one side of the plurality of electrodes 31. These electrode tabs 51 can be welded to each other and electrically connected. An electrode lead 55 may be connected to the electrode tab 51 to form an electrode terminal outside the case 10. Such a connection portion 50 may have a V-shaped bent groove.

Conventional electrode assemblies have been found to be desirable for placing the separator on the outermost layer. However, this form has a problem because it has many limitations in terms of capacity, safety, and appearance characteristics of the secondary battery.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide an electrode assembly that maximizes the capacity of a secondary battery, improves safety, and improves the appearance of the secondary battery.

An electrode assembly according to the present invention includes: a unit stack having a structure in which a plurality of electrodes and a separator are alternately stacked; And a polymer film part arranged to be in contact with the outer surface of the outermost electrode of the unit stack part. The size of the polymer film part is equal to or larger than the size of the outermost electrode.

An electrode assembly according to the present invention includes: a unit stack having a structure in which a plurality of electrodes and a separator are alternately stacked; And the polymer film portion disposed so as to be in contact with the outer surface of the outermost electrode of the unit stack portion, thereby maximizing the capacity of the secondary battery, improving safety, and improving the appearance of the secondary battery.

1 is an exploded perspective view showing a structure in which a conventional electrode assembly is embedded in a case of a secondary battery.
2 is a perspective view showing a state in which the secondary battery is assembled in the drawing of FIG.
3 is a perspective view showing an electrode assembly according to Embodiment 1 of the present invention.
4 is a cross-sectional view showing a process of bonding an electrode and a polymer film.
5 is a side view showing the first structure of the basic unit.
6 is a side view showing the second structure of the basic unit.
FIG. 7 is a side view showing a unit stack formed by stacking the basic unit of FIG. 5;
8 is a side view showing the third structure of the basic unit.
9 is a side view showing a fourth structure of the basic unit.
10 is a side view showing a unit stack formed by stacking the basic unit of FIG. 8 and the basic unit of FIG. 9. FIG.
11 is a process drawing showing a process of manufacturing a basic unit.
12 is a perspective view showing a unit stack formed by stacking basic unit bodies having different sizes.
13 is a side view showing the unit stack of FIG.
14 is a perspective view showing a unit stack portion in which basic unit pieces having different geometric shapes are laminated.
15 is a side view showing a first structure of the unit stack portion including the basic unit and the first auxiliary unit.
16 is a side view showing the second structure of the unit stack portion including the basic unit and the first auxiliary unit.
17 is a side view showing a third structure of the unit stack portion including the basic unit and the second auxiliary unit.
18 is a side view showing a fourth structure of the unit stack portion including the basic unit and the second auxiliary unit.
19 is a side view showing a fifth structure of the unit stack portion including the basic unit and the first auxiliary unit.
20 is a side view showing a sixth structure of the unit stack portion including the basic unit and the first auxiliary unit.
21 is a side view showing a seventh structure of the unit stack portion including the basic unit and the second auxiliary unit.
22 is a side view showing an eighth structure of a unit stack portion including a basic unit and a second auxiliary unit.
23 is a side view showing a ninth structure of the unit stack portion including the basic unit and the first auxiliary unit.
24 is a side view showing a tenth structure of the unit stack portion including the basic unit body, the first auxiliary unit body, and the second auxiliary unit body.
25 is a side view showing an eleventh structure of the unit stack portion including the basic unit and the second auxiliary unit.
26 is a cross-sectional view showing a polymer film portion attached to a unit stack portion including an auxiliary unit in the electrode assembly according to Embodiment 1 of the present invention.
27 is a perspective view showing an electrode assembly according to a second embodiment of the present invention.
28 is a perspective view showing an electrode assembly according to a third embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the following examples.

Example  One

3 is a perspective view showing an electrode assembly according to Embodiment 1 of the present invention.

Hereinafter, an electrode assembly according to a first embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 3, an electrode assembly 1000 according to Embodiment 1 of the present invention includes a unit stack portion 1700 and a polymer film portion 1300.

The unit stack unit 1700 has a structure in which a plurality of electrodes and a plurality of separators 1115 are alternately stacked. The unit stack section 1700 may have a structure in which the same number of electrodes and the separating films 1115 are alternately arranged and the basic unit bodies integrally coupled are repeatedly arranged. The detailed structure of the unit stack 1700 including the basic unit body will be described later.

On the other hand, the outermost electrode among the plurality of electrodes of the unit stack 1700 is the outermost electrode 1191. In FIG. 3, the uppermost electrode or the lowermost electrode is the outermost electrode 1191.

In FIG. 3, the arrangement of the outermost electrode 1191 can be confirmed. Fig. 3 shows a top enlarged view (U) showing the top section of the electrode assembly 1000 according to the first embodiment of the present invention and a bottom enlarged view (D) showing the bottom section. The arrangement of the outermost electrode 1191 is specifically shown in the uppermost enlarged view (U) and the lowermost enlarged view (D).

In the electrode assembly 1000 according to the first embodiment of the present invention, the polymer film portion 1300 is disposed in contact with the outer surface of the outermost electrode 1191 of the unit stack portion 1700. The polymer film portion 1300 may be an insulator having no electrical conductivity or an insulating polymer film. Particularly, the polymer film part 1300 may be made of a material such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI) And combinations thereof.

The size of the polymer film portion 1300 may be equal to or greater than the size of the outermost electrode 1191 for electrical insulation.

When the polymer film part 1300 is arranged to be in contact with the outer surface of the outermost electrode 1191 as described above, the polymer film part 1300 is formed on the outermost layer of the electrode assembly 1000 according to the first embodiment of the present invention .

When the polymer film part 1300 is positioned at the outermost layer of the electrode assembly 1000, the safety of the secondary battery can be remarkably improved. When the polymer film portion 1300 is located on the outermost layer as in the electrode assembly 1000 according to the first embodiment of the present invention, the safety of the battery is improved more than that of the conventional secondary battery where the separator is located on the outermost layer Can be remarkably improved.

The separator 1115 is thin and has a high porosity so that it tears immediately when pierced by a sharp nail or the like. On the other hand, the polymer film part 1300 has a high elongation property. Therefore, when the polymer film portion 1300 is pierced with a sharp nail or the like, the polymer film portion 1300 is stretched rather than torn. Assuming that the secondary battery is penetrated from the outside by a pointed object such as a nail, if the separator is located in the outermost layer, the separator may be torn immediately, resulting in a short-term accident.

However, if the polymer film portion 1300 is present on the outermost layer of the electrode assembly 1000, even if the secondary battery is penetrated from the outside by a pointed object such as a nail, the polymer film portion 1300 is stretched to penetrate through the pointed object (Not shown), so that an immediate shot (or short circuit) can be prevented, and the time for shorting can be delayed. By preventing and delaying electrical shorts as described above, the safety of the secondary battery can be remarkably improved.

When the polymer film part 1300 is located at the outermost layer of the electrode assembly 1000, the outer surface of the secondary battery, in which the electrode assembly 1000 is inserted, Can be remarkably improved.

The separation membrane 1115 has many holes and is sufficiently impregnated with the electrolyte. So that the rigidity is deteriorated. Therefore, when such a separator 1115 is located on the outermost layer of the electrode assembly, the appearance may not be smooth and a curved shape may be formed. Further, since the separator 1115 has a property of shrinking at high temperature storage, the surface of the secondary battery 1115 may become uneven.

On the other hand, since the polymer film portion 1300 has no pores and the degree of impregnation with the electrolytic solution is significantly lowered, the rigidity is significantly higher than that of the separator 1115. Therefore, when the polymer film portion 1300 is located on the outermost layer of the electrode assembly 1000, the outer appearance of the secondary battery can be smooth and flat. Since the polymer film portion 1300 shrinks considerably even when stored at a high temperature, the surface of the secondary battery can be prevented from being rugged due to high temperature storage.

Meanwhile, since the polymer film portion 1300 is located on the outermost layer of the electrode assembly 1000, the problem of stickiness that may occur in the manufacturing process of the secondary battery may be improved.

When the separator is laminated together with another unit stack (not shown) or another basic unit (not shown) while the separator is located on the outermost layer, the separation membranes may stick to each other. Since there are many holes in the separation membrane, the adhesive material applied on the inner side of the separation membrane can leak out to the outer side of the separation membrane, so that the separation membrane can be formed with adhesive layers on both sides. In this case, there may arise a problem that the unit stack portion, which is additionally stacked on the outer side of the separator, or the sticking property of the base unit stack, which is attached to the unit stack portion or the basic unit,

The separator also has a high electrostatic property, so that when the separator is located on the outermost layer, the problem of stickiness can be caused more by static electricity.

When there is a need to temporarily stack the unit stack or the basic unit, and then remove it again, this stickiness problem can cause great difficulty in the battery manufacturing process.

Therefore, if the polymer film portion 1300 is located at the outermost layer of the electrode assembly 1000, the problem of stickiness can be prevented.

Since the polymer film part 1300 does not have holes, the adhesive material on the inner surface does not leak out, and thus the problem of stickiness between the stacked unit parts 1700 or the basic unit parts is not generated Do not.

In the electrode assembly 1000 according to the first embodiment of the present invention, the outermost electrode 1191 is formed in a region in contact with the separation membrane 1115, as shown in the uppermost enlarged view (U) and the lowermost enlarged view (D) Only the electrode active material (or the active material) may be coated. When the outermost electrode 1119 is a cathode, the electrode active material refers to the anode active material 1117.

In other words, the negative electrode active material 1117 may not be coated on the surface of the outermost electrode 1191 facing the polymer film portion 1300 (when the outermost electrode is the negative electrode). The electrode for coating the active material on only one side may be referred to as a single-sided electrode. In the electrode assembly 1000 according to the first embodiment of the present invention, the outermost electrode 1191 may be formed as a single-sided electrode.

The electrode assembly 1000 can be effectively manufactured by forming the outermost electrode 1191 as a cross-section electrode because the polymer film portion 1300 is disposed at the outermost portion of the electrode assembly 1000. If the separator 1115 is located at the outermost position of the electrode assembly, the cross-sectional electrode attached to the separator may bend or dry if the cross-section electrode is used. Unlike the polymer film portion 1300, the separation membrane 1115 has a plurality of holes, and the rigidity thereof is deteriorated.

In the case of the polymer film portion 1300, since there is no pore and has a predetermined rigidity, the cross-section electrode may not bend even if it is attached together with the cross-section electrode. In this manner, the polymer film portion 1300 can make use of the cross-section electrode.

If the end face electrode can be used as the outermost electrode 1191 in the electrode assembly 1000, the capacity of the secondary battery can be maximized.

When the active material is coated on the outer surface of the outermost electrode, the active material is a part that does not react to generate electrical energy (hereinafter referred to as a battery reaction). Therefore, even if the active material on the outer surface of the outermost electrode is eliminated, there is no great difference in the capacity of the secondary battery. That is, the cross-sectional electrode can have the same capacitance with a thickness smaller than that of the electrode coated with active material on both sides (hereinafter referred to as a double-sided electrode). As a result, the secondary battery using the single-sided electrode can exhibit the same capacity even with a smaller thickness.

In this case, if the active material of the battery reaction area is increased by the reduced thickness, the secondary battery having the same thickness as the existing secondary battery and maximizing the electric capacity can be produced.

Meanwhile, if the end face electrode can be used as the outermost electrode 1191 in the electrode assembly 1000, the safety of the secondary battery can be further improved.

Since the active materials 1111 and 1117 themselves are an unstable substance that easily causes a chemical reaction, it may mean that safety is further improved even with a cross-sectional electrode itself, which is partially removed.

Further, the thickness of the cathode current collector 1113 or the anode current collector 1119, which is a base material coated with the active material, can be made thicker by using the space generated by the active material, 1113 and 1119 can further improve the safety remarkably.

4 is a cross-sectional view showing a process of bonding an electrode and a polymer film.

Referring to FIG. 4, the outermost electrode 1191 and the polymer film portion 1300 may be bonded to each other. At this time, the adhesion between the electrode and the polymer film portion 1300 may be an adhesion by applying a pressure using a roll press (P). Or the adhesion between the electrode and the polymer film portion 1300 may be adhesion by applying pressure and heat together. In addition, the adhesion between the electrode and the polymer film portion 1300 may be adhesion by lamination. In this way, the electrode and the polymer film portion 1300 can be firmly attached to each other.

[Structure of Unit Stack Part]

The unit stack 1700 included in the electrode assembly according to the first embodiment of the present invention is formed by alternately stacking electrodes and a separator 1115. However, the unit stack unit 1700 may have a more specific and specific internal structure.

That is, the unit stack unit 1700 included in the electrode assembly 1000 according to the first embodiment of the present invention may have a structure in which basic unit members are stacked.

Here, the unit stack portion may have a structure in which one kind of basic unit bodies are repeatedly arranged, or two or more kinds of basic unit bodies may have a structure, for example, alternately arranged in a predetermined order.

In order to explain the concrete structure of the unit stack portion, the contents of what is the basic unit body will be described below.

[Structure of Basic Unit Structure]

In the electrode assembly 1000 according to the first embodiment of the present invention, the basic unit is formed by alternately arranging the electrodes and the separator. At this time, the same number of electrodes and separator are arranged. For example, as shown in FIG. 5, the basic unit body 110a may be formed by stacking two electrodes 111 and 113 and two separation membranes 112 and 114. At this time, the positive electrode and the negative electrode can naturally face each other through the separator. When the basic unit body is thus formed, the electrodes (see reference numeral 111 in Fig. 5 and Fig. 6) are positioned at one end of the basic unit body, and the separator (reference numerals in Figs. 5 and 6 114 separator) is located.

The electrode assembly 1000 according to the first embodiment of the present invention has a basic feature in that the unit stack can be formed only by stacking the basic unit. That is, a basic feature is that one kind of basic unit body is repeatedly laminated, or two or more kinds of basic unit bodies are stacked in a predetermined order to form a unit body stack part. In order to realize such a characteristic, the basic unit may have the following structure.

First, the basic unit may be formed by sequentially stacking a first electrode, a first separator, a second electrode, and a second separator. 5, the first unit electrode 111, the first separation membrane 112, the second electrode 113, and the second separation membrane 114 are arranged on the lower side Or the first electrode 111, the first separator 112, the second electrode 113 and the second separator 114 may be sequentially stacked from the lower side to the upper side as shown in FIG. 6, . The basic unit having such a structure is hereinafter referred to as a first basic unit. Here, the first electrode 111 and the second electrode 113 are opposite to each other. For example, if the first electrode 111 is a positive electrode, the second electrode 113 is a negative electrode.

When the first electrode, the first separator, the second electrode, and the second separator are stacked in this order to form the basic unit, as shown in FIG. 7, only one basic unit body 110a is repeatedly stacked So that the unit stack portion 100a can be formed. In addition to the four-layer structure, the basic unit may have an eight-layer structure or a twelve-layer structure. That is, the basic unit may have a structure in which a four-layer structure is repeatedly arranged. For example, the basic unit may include a first electrode, a first separator, a second electrode, a second separator, a first electrode, a first separator, a second electrode, and a second separator.

Second, the basic unit may be formed by stacking a first electrode, a first separator, a second electrode, a second separator, a first electrode, and a first separator in this order, or a second electrode, a second separator, 1 separator, a second electrode, and a second separator may be sequentially stacked. The basic unit having the former structure will hereinafter be referred to as a second basic unit and the basic unit having the latter structure will be referred to as a third basic unit hereinafter.

More specifically, as shown in FIG. 8, the second basic unit 110c includes a first electrode 111, a first separator 112, a second electrode 113, a second separator 114, The first separator 111 and the first separator 112 may be sequentially stacked from the upper side to the lower side. 9, the third basic unit 110d includes a second electrode 113, a second separation membrane 114, a first electrode 111, a first separation membrane 112, a second electrode 113 And the second separation membrane 114 may be sequentially stacked from the upper side to the lower side. Alternatively, they may be stacked in order from the lower side to the upper side.

When only one second basic unit 110c and one third basic unit 110d are stacked, a structure in which a four-layer structure is repeatedly stacked is formed. Therefore, if the second basic unit 110c and the third basic unit 110d are sequentially stacked alternately one after another, as shown in FIG. 10, the unit stack portion 100b is formed only by stacking the second and third basic units can do.

As described above, in the electrode assembly according to the first embodiment of the present invention, one kind of basic unit body has a four-layer structure or a four-layer structure in which the first electrode, the first separation membrane, the second electrode and the second separation membrane are sequentially arranged, As shown in FIG. When two or more kinds of basic unit bodies are arranged in a predetermined order, a structure in which a four-layer structure or a four-layer structure is repeatedly arranged is formed. For example, when the first basic unit has a four-layer structure and two second basic units and three second basic units are stacked one upon the other, a twelve-layer structure in which a four-layer structure is repeatedly stacked .

Therefore, when one kind of basic unit body is repeatedly laminated or two or more kinds of basic unit bodies are laminated in a predetermined order, a unit stack can be formed only by lamination.

In the electrode assembly according to the first embodiment of the present invention, the unit stack portion is formed by stacking the basic unit units in units of basic units. That is, first, a basic unit body is manufactured, and then it is repeatedly or stacked in a predetermined order to produce a unit body stack portion. Thus, the unit stack can be formed only by stacking the basic unit pieces. In this case, the basic unit can be very precisely aligned. When the basic unit is precisely aligned, the electrode and the separator can be precisely aligned in the unit stack. In addition, the productivity of the unit stack can be greatly improved. This is because the process becomes very simple.

[Production of basic unit]

Referring to FIG. 11, a process for manufacturing the first basic unit will be described. First, a first electrode material 121, a first separation material 122, a second electrode material 123, and a second separation material 124 are prepared. Here, the first membrane material 122 and the second membrane material 124 may be the same material. The first electrode material 121 is cut to a predetermined size through the cutter C ₁ and the second electrode material 123 is cut to a predetermined size through the cutter C ₂ . The first electrode material 121 is then laminated to the first separator material 122 and the second electrode material 123 is laminated to the second separator material 124.

It is then preferable to adhere the electrode material and the separation membrane material to each other in the laminator (L ₁ , L ₂ ). By such adhesion, a basic unit in which the electrode and the separator are integrally combined can be produced. The methods of combining can vary. The laminator (L ₁ , L ₂ ) applies pressure or heat to the material for adhesion. Such adhesion makes it easier to laminate the base unit when the unit unit stack is manufactured. Such bonding is also advantageous for alignment of the basic unit. When the first separation membrane material 122 and the second separation membrane material 124 are cut to a predetermined size through the cutter C ₃ after the adhesion, the basic unit body 110a can be manufactured. During this process, the ends of the separator may not be joined to the ends of the adjacent separator.

As described above, in the basic unit, the electrodes can be adhered to the adjacent separation membrane. Or the separator is bonded to the electrode. At this time, it is preferable that the electrodes are adhered to the separator as a whole on the surface facing the separator. This is because the electrode can be stably fixed to the separator. Typically, the electrode is smaller than the separator.

To this end, an adhesive may be applied to the separator. However, in order to use the adhesive in this way, it is necessary to apply the adhesive in the form of a mesh or a dot over the adhesive surface. If an adhesive is applied to the entire adhesion surface without any gaps, reactive ions such as lithium ions can not pass through the separation membrane. Therefore, if an adhesive is used, it is difficult to bond the electrode as a whole even though the electrode can be adhered to the separator as a whole (that is, over the entire adhesive surface).

Alternatively, the electrodes can be adhered to the separator as a whole through the separator having the coating layer having the adhesive force. Will be described in detail. The separator may comprise a porous separator substrate, such as a polyolefin-based separator substrate, and a porous coating layer that is entirely coated on one or both sides of the separator substrate. Wherein the coating layer can be formed of a mixture of binder polymers that connect and fix the inorganic particles and the inorganic particles to each other.

Herein, the inorganic particles can improve the thermal stability of the separator. That is, the inorganic particles can prevent the separation membrane from contracting at a high temperature. And the binder polymer can fix the inorganic particles and improve the mechanical stability of the separator. Further, the binder polymer can adhere the electrode to the separation membrane. Since the binder polymer is distributed throughout the coating layer, unlike the above-mentioned adhesive, adhesion can be gently formed on the whole of the adhesion surface. Therefore, by using such a separation membrane, the electrode can be more stably fixed to the separation membrane. In order to enhance such adhesion, the laminator described above can be used.

However, the inorganic particles may form a densely packed structure to form interstitial volumes between the inorganic particles as a whole in the coating layer. At this time, a pore structure can be formed in the coating layer by the interstitial volume defined by the inorganic particles. Even if a coating layer is formed on the separation membrane due to such a pore structure, lithium ions can pass through the separation membrane well. For reference, the interstitial volume defined by the inorganic particles may be blocked by the binder polymer depending on the position.

Here, the filling structure can be described as a structure in which gravel is contained in a glass bottle. Accordingly, when the inorganic particles are filled, the interstitial volume between the inorganic particles is not locally formed in the coating layer, but the interstitial volume is formed between the inorganic particles as a whole in the coating layer. Accordingly, as the size of the inorganic particles increases, the pore size due to the interstitial volume also increases. Due to such a charging structure, lithium ions can smoothly pass through the separator on the entire surface of the separator.

On the other hand, the basic unit bodies in the unit body stack portion can also be bonded to each other. For example, in FIG. 5, if the lower surface of the second separation membrane 114 is coated with an adhesive or the coating layer is coated, another basic unit body may be adhered to the lower surface of the second separation membrane 114.

In this case, the adhesion force between the electrode and the separator in the basic unit may be greater than the adhesion between the basic units in the unit stack. Of course, there may be no adhesion between the base units. In this case, when the unit stack portion is separated, there is a high possibility that it is separated into units of the basic unit due to the difference in the adhesive strength. For reference, the adhesive force may be expressed by the peeling force. For example, the adhesive force between the electrode and the separator may be expressed as the force required to separate the electrode and the separator from each other. In this way, the basic unit body in the unit stack can not be combined with the adjacent basic unit body, or can be combined with the adjacent basic unit body in a bonding force different from that of the electrode and separator bonded to each other in the basic unit body.

For reference, ultrasonic welding of the separator is not preferable when the separator includes the above-mentioned coating layer. The separator is typically larger than the electrode. Accordingly, there is an attempt to bond the ends of the first separator 112 and the ends of the second separator 114 by ultrasonic welding. However, it is necessary to pressurize the object directly with ultrasonic welding. However, if the end of the membrane is directly pressed by the horn, the coating layer having an adhesive force may adhere to the membrane. This can lead to device failure.

[Variation of basic unit body]

Up to now, only basic unit pieces having the same size have been described. However, the basic unit may have different sizes. By stacking the basic unit bodies having different sizes, the unit body stack unit can be manufactured in various shapes. Here, the size of the basic unit is described based on the size of the separation membrane. This is because the separator is usually larger than the electrode.

12 and 13, the basic unit pieces may be divided into at least two groups having a plurality of different sizes (see reference numerals 1101a, 1102a, and 1103a in FIG. 13). When such basic unit bodies are stacked according to their sizes, a unit body stack unit 100c having a plurality of stages can be formed. 12 and 13 illustrate an example in which three basic unit bodies 1101a, 1102a, and 1103a, which are divided into three groups, are stacked to form three ends. For reference, the basic unit pieces belonging to one group may form two or more stages.

However, when the plurality of stages are formed, it is most preferable that the basic unit has a structure in which the above-described four-layer structure or four-layer structure is repeatedly laminated, that is, the structure of the first basic unit. (In the present specification, the basic unit bodies are regarded as belonging to one kind of basic unit body even if they are different in size if they have the same lamination structure.)

In detail, it is preferable that the number of the positive electrodes and the number of the negative electrodes are the same. It is preferable that electrodes opposite to each other between the first and second ends are opposed to each other through the separator. However, for example, in the case of the second and third basic unit bodies, two kinds of basic unit bodies are required to form one stage as described above.

However, as shown in FIG. 13, in the case of the first basic unit, only one basic unit is required to form one stage as described above. Therefore, if the basic unit has a structure in which the above-described four-layer structure or four-layer structure is repeatedly laminated, the number of basic unit pieces can be reduced even if a plurality of stages are formed.

Also, for example, in the case of the second and third basic unit bodies, at least one of the two basic unit bodies needs to be stacked in order to form one stage as described above, so that one stage has a structure of at least 12 layers. However, in the case of the first basic unit, only one basic unit may be stacked to form one stage as described above, so that one stage has a structure of at least four layers. Therefore, when the basic unit has a structure in which the above-described four-layer structure or four-layer structure is repeatedly laminated, the thickness of each end can be very easily adjusted when forming a plurality of stages.

On the other hand, the basic unit bodies may have different sizes or may have different geometric shapes. For example, as shown in FIG. 14, the basic unit bodies may have a difference in edge shape as well as a size, and there may be a difference in the presence or absence of punching. More specifically, as shown in Fig. 14, the basic unit pieces divided into three groups may be stacked with each other to form three stages, in which the basic unit pieces having the same geometric shape are stacked. For this purpose, the basic unit may be divided into at least two groups (each group having a different geometric shape). Also in this case, it is most preferable that the basic unit has a structure in which the above-described four-layer structure or four-layer structure is repeatedly laminated, that is, the structure of the first basic unit. (In the present specification, if the basic unit bodies have the same lamination structure, they are regarded as belonging to one kind of basic unit body even though their geometrical shapes are different from each other.)

[Auxiliary unit]

The unit stack may further include at least one of the first auxiliary unit and the second auxiliary unit. First, the first auxiliary unit will be described. In the electrode assembly according to the first embodiment of the present invention, the basic unit has electrodes at one end and a separator at the other end. Accordingly, when the basic unit bodies are sequentially stacked, the electrodes (reference numeral 116 in Fig. 15, hereinafter referred to as " terminal electrodes ") are located at the uppermost or bottommost portion of the unit stack. The first auxiliary unit is further laminated to such a terminal electrode.

More specifically, if the terminal electrode 116 is a positive electrode, the first auxiliary unit body 130a is separated from the separation electrode 114 in order from the terminal electrode 116, that is, outwardly from the terminal electrode 116, A cathode 113, a separator 112, and an anode 111 in this order. If the terminal electrode 116 is a cathode, the first auxiliary unit body 130b is electrically connected to the separator 114 and the anode 114 in order from the terminal electrode 116, that is, outwardly from the terminal electrode 116, (113) may be sequentially stacked.

As shown in FIGS. 15 and 16, the unit stacks 100d and 100e can position the anode at the outermost side of the terminal electrode through the first auxiliary unit bodies 130a and 130b. At this time, it is preferable that the anode located at the outermost side, that is, the anode of the first auxiliary unit body is coated on the active material layer only on one side (one side looking downward with reference to FIG. When the active material layer is coated as described above, the active material layer is not located on the outermost side of the end electrode side, so that the active material layer can be prevented from being wasted. For reference, since the anode is configured to emit lithium ions (for example), it may be advantageous in battery capacity if the anode is located at the outermost position.

Next, the second auxiliary unit will be described. The second auxiliary unit basically performs the same function as the first auxiliary unit. Will be described in detail. The basic unit has an electrode at one end and a separator at the other end. Accordingly, when the basic unit bodies are sequentially stacked, the separation membrane (refer to separation membrane 117 in FIG. 17, hereinafter referred to as "separation membrane") is located at the uppermost or bottommost portion of the unit cell stack. The second auxiliary unit is additionally stacked on such a terminal separation membrane.

More specifically, if the electrode 113 in contact with the end separator 117 in the basic unit body is a positive electrode, the second auxiliary unit 140a is divided into the cathodes 111, A separator 112 and an anode 113 may be stacked. If the electrode 113 in contact with the end separator 117 in the basic unit is a negative electrode, the second auxiliary unit 140b may be formed of the positive electrode 111 as shown in FIG.

As shown in FIGS. 17 and 18, the unit stack portions 100f and 100g can position the anode at the outermost side of the terminal separator through the second auxiliary unit bodies 140a and 140b. At this time, the anode located at the outermost position, that is, the anode of the second auxiliary unit, is disposed on both sides of the current collector in the same manner as the anode of the first auxiliary unit body (only one side viewed from the top in FIG. 17) It may be desirable to coat the active material layer.

However, the first auxiliary unit and the second auxiliary unit may have structures different from those described above. First, the first auxiliary unit will be described. 19, if the terminal electrode 116 is a cathode, the first auxiliary unit body 130c may be formed by sequentially stacking the separation membrane 114 and the cathode 113 from the terminal electrode 116. [ 20, the first auxiliary unit body 130d includes a separation membrane 114, a cathode 113, a separation membrane 112, and a cathode 111 which are connected to the terminal electrodes 116 ) In this order.

As shown in FIGS. 19 and 20, the unit stack portions 100h and 100i can position the cathodes on the outermost sides of the terminal electrodes through the first auxiliary unit bodies 130c and 130d.

Next, the second auxiliary unit will be described. As shown in FIG. 21, if the electrode 113 in contact with the terminal separating film 117 in the basic unit body is a positive electrode, the second auxiliary unit body 140c may be formed of the negative electrode 111. 22, when the electrode 113 in contact with the terminal separator 117 in the basic unit is a cathode, the second auxiliary unit 140d includes the positive electrode 111, the separator 112, and the negative electrode 13, May be stacked in this order from the terminal separation membrane 117. As shown in FIGS. 21 and 22, the unit stack portions 100j and 100k can position the cathodes on the outermost side of the terminal separation membrane through the second auxiliary unit bodies 140c and 140d.

For reference, the cathode may cause a reaction with an aluminum layer of a battery case (e.g., a pouch-shaped case) due to a potential difference. Therefore, it is preferable that the negative electrode is insulated from the battery case through the separator. To this end, the first and second auxiliary unit bodies may further include a separation membrane on the outer side of the cathode in FIG. 19 to FIG. For example, in contrast to the first auxiliary unit 130c of FIG. 19, the first auxiliary unit 130e of FIG. 23 may further include a separation membrane 112 on the outermost side. However, in the electrode assembly according to the first embodiment of the present invention, a polymer film may be used instead of the outermost separator 112.

On the other hand, the unit stack portion 100m may be formed as shown in Fig. The basic unit body 110b may include a first electrode 111, a first separator 112, a second electrode 113, and a second separator 114 stacked in this order from the lower side to the upper side. Here, the first electrode 111 may be an anode and the second electrode 113 may be a cathode.

The first auxiliary unit 130f may be formed by sequentially laminating a separation membrane 114, a cathode 113, a separation membrane 112, and an anode 111 from a terminal electrode 116. At this time, the anode 111 of the first auxiliary unit 130f may have an active material layer formed on only one surface of the collector facing the basic unit 110b.

The second auxiliary unit 140e includes an anode 111, a separator 112, a cathode 113, a separator 114 and a cathode 118 (second anode) sequentially from the terminal separator 117 May be stacked. At this time, the anode (118, the second anode) located at the outermost one of the anode of the second auxiliary unit 140e may have an active material layer only on one side of the collector facing the basic unit 110b.

Finally, the unit stack portion 100n may be formed as shown in FIG. The basic unit 110e may include a first electrode 111, a first separator 112, a second electrode 113, and a second separator 114 stacked from the upper side to the lower side. In this case, the first electrode 111 may be a cathode and the second electrode 113 may be a cathode. The second auxiliary unit 140f may be formed by sequentially laminating the cathode 111, the separation membrane 112, the anode 113, the separation membrane 114, and the cathode 119 from the terminal separation membrane 117.

26 is a cross-sectional view showing a polymer film portion attached to a unit stack portion including an auxiliary unit in the electrode assembly according to Embodiment 1 of the present invention.

Referring to FIG. 26, the basic unit body 1500 has a structure in which an anode 1131, a separation membrane 1115, a cathode 1151, and a separation membrane 1115 are stacked. In the configuration in which the basic unit bodies 1500 are sequentially stacked, the electrode located on the uppermost layer may be the terminal electrode 1211. [ In this case, the terminal electrode 1211 may be an anode. On the other hand, in the structure in which the basic unit bodies 1500 are sequentially stacked, the terminal separation membrane 1231 can be positioned at the lowest layer.

The first auxiliary unit body 1510 may be further stacked above the terminal electrode 1211 and the second auxiliary unit body 1530 may be disposed below the terminal separation membrane 1231. [ Here, the first auxiliary unit body 1510 may be formed by sequentially arranging the separation membrane 1115 and the cathode 1151 from the terminal electrode 1211. The second auxiliary unit body 1530 may be formed by sequentially arranging the anode 1131, the separation membrane 1115 and the cathode 1151 from the terminal separation membrane 1231.

The polymer film portion 1300 may be disposed on the outer surface of the outermost cathode 1151 of the first auxiliary unit body 1510 and the second auxiliary unit body 1530. In addition, the outermost cathode 1151 and the polymer film portion 1300 may be adhered to each other.

Example  2

27 is a perspective view showing an electrode assembly according to a second embodiment of the present invention.

The electrode assembly according to the second embodiment of the present invention has a configuration similar to that of the electrode assembly according to the first embodiment described above. However, the second embodiment differs from the first embodiment in that it further includes an electrode tab and an extension.

For the sake of reference, the same (or significant) reference numerals are given to the same (or significant) parts as those of the above-described configuration, and a detailed description thereof will be omitted.

Hereinafter, an electrode assembly according to a second embodiment of the present invention will be described with reference to FIG.

27, the electrode assembly 2000 according to the second embodiment of the present invention includes a unit stack unit 1700 and a unit stack unit 1700 having a structure in which a plurality of electrodes and separation membranes 1115 are alternately stacked, And a polymer film portion 1300 arranged to be in contact with the outer surface of the outermost electrode 1191 of the polymer film portion 1100. The electrode assembly 2000 of the second embodiment has the same advantages as those of the first embodiment except that the electrode assembly 2000 includes electrode tabs 1251 extending from the ends of the plurality of electrodes and electrode tabs 1251 extending from the polymer film part 1300 in the direction of the electrode tabs 1251 And further includes an extension portion 1310.

The extension portion 1310 may be an insulator having no specific electrical conductivity, or an insulating polymer film. Particularly, the extension portion 1310 may be made of a material such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI) And combinations thereof.

At this time, the extension part 1310 may be formed of the same material as the polymer film part 1300, and may be formed integrally with the polymer film part 1300.

There is an effect that the electrode tab 1251 can be protected by the extension portion 1310. The extension portion 1310 can cover the electrode tab 1251, so that the electrode tab 1251 can be prevented from being damaged.

In addition, the extension portion 1310 also has an effect of significantly improving the safety of the battery. That is, the extension portion 1310 can prevent a short-circuit accident caused by the contact of the electrode tab 1251 with the other conductive member, and the safety of the battery can be remarkably increased.

Particularly, when the extension portion 1310 is welded together with the electrode tab 1251, the protective tape for the electrode tab 1251 used for protecting the electrode tab 1251 may not be used any more . Thereby reducing the process cost and process time. Welding of the extension portion 1310 and the electrode tab 1251 may be performed by ultrasonic welding.

Example  3

28 is a perspective view showing an electrode assembly according to a third embodiment of the present invention.

The electrode assembly according to the third embodiment of the present invention has a configuration similar to that of the electrode assembly according to the second embodiment described above. However, the third embodiment differs from the second embodiment in that the extension portion is curved.

For the sake of reference, the same (or significant) reference numerals are given to the same (or significant) parts as those of the above-described configuration, and a detailed description thereof will be omitted.

Hereinafter, an electrode assembly according to a third embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 28, the electrode assembly 3000 according to the third embodiment of the present invention includes a plurality of electrode tabs 1251 extending from the ends of the plurality of electrodes, The welded portion 1253 can be formed.

At this time, the extension portion 1310 may have a bent shape toward the welded portion 1253. 28, the uppermost extensions 1310 are bent downwardly toward the welds 1253 in the drawing, and the lowermost extensions 1310 are bent upwardly toward the welds 1253 It is bent in the direction.

The extended portion 1310 can basically prevent the pouch and the electrode tab 1251 from being short-circuited. The bent portion 1310 has a further effect, It is possible to prevent the lead portion 1253 and the lead portion 1271 from being shorted to each other. In other words, it is possible to prevent the ends of the electrode tabs 1251 facing the unit stack 1700 and the lead portions 1271 from being shorted to each other.

In the case of the conventional secondary battery, if the battery shakes due to the movement of the battery or the like, the welded portion 1253 and the lead portion 1271 may contact each other, resulting in a short-circuit accident. The electrode assembly 3000 according to the third embodiment of the present invention is provided with the bent extension portion 1310 to prevent the welded portion 1253 and the lead portion 1271 from being shorted to each other. Accordingly, the safety of the secondary battery can be further ensured.

While the present invention has been described in connection with certain exemplary embodiments and drawings, it is to be understood that the present invention is not limited thereto and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

1: secondary battery
10: Case
30: Electrode assembly
31: Electrode
33: Membrane
50: Connection
51: Electrode tab
55: Electrode lead
100a to 100n:
110a to 110e: basic unit
111: first electrode
112: first separator
113: second electrode
114: second separator
116: terminal electrode
117: terminal membrane
121: first electrode material
122: first separation membrane material
123: second electrode material
124: Second separation membrane material
130a to 130f: a first auxiliary unit body
140a to 140f: a second auxiliary unit
1111: cathode active material
1113: positive collector
1115: Membrane
1117: anode active material
1119: cathode collector
1131: anode
1151: cathode
1191: Outermost electrode
1211: terminal electrode
1231: terminal membrane
1251: electrode tab
1253:
1271:
1300: Polymer film part
1310: Extension part
1500: basic unit
1510: First auxiliary unit
1530: Second auxiliary unit
1700: unit stack unit
P: roll press

Claims (32)

A unit stack portion having a structure in which a plurality of electrodes and a separation membrane are alternately stacked; And
And a polymer film portion disposed to be in contact with an outer surface of the outermost electrode of the unit stack portion,
Wherein the size of the polymer film portion is equal to or greater than the size of the outermost electrode. The method according to claim 1,
The polymer film part may be made of any one selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI) The electrode assembly comprising: The method according to claim 1,
Wherein the outermost electrode is coated with an active material only in a region where the outermost electrode is in contact with the separation membrane. The method according to claim 1,
Wherein the outermost electrode and the polymer film portion are bonded to each other. The method of claim 4,
Wherein the adhesion between the outermost electrode and the polymer film part is adhesion by pressure or adhesion by pressure and heat. The method according to claim 1,
An electrode tab extending from an end of the plurality of electrodes; And
And an extension extending from the polymer film portion in a direction in which the electrode tab is formed. The method of claim 6,
The extended portion may be formed of any one selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI) . The method of claim 6,
Wherein the extension is welded together with the electrode tab. The method of claim 6,
The electrode tabs extending from the plurality of electrodes are welded to each other to form a welded portion,
Wherein the extension portion is bent toward the welded portion. The method according to any one of claims 1 to 9,
The unit stack portion may include (a) a structure in which one kind of basic unit bodies, in which the same number of electrodes and separation membranes are alternately arranged and integrally combined, are repeatedly arranged, or (b) Two or more kinds of basic unit bodies arranged and integrally joined are arranged in a predetermined order,
The one type of basic unit of (a) has a four-layer structure in which a first electrode, a first separation membrane, a second electrode, and a second separation membrane are sequentially stacked, or a structure in which the four-layer structure is repeatedly laminated,
Wherein a structure in which the four-layer structure or the four-layer structure is repeatedly formed is formed by laminating the two or more kinds of the basic unit bodies of (b) one by one in a predetermined order. The method of claim 10,
Wherein the basic unit body is not coupled to the adjacent basic unit body in the unit body stack unit or is coupled with the adjacent basic unit body in a bonding force different from the coupling force of the electrode and the separation membrane in the basic unit body. . The method of claim 10,
The one kind of basic unit (a) includes a first basic unit having a structure in which the four-layer structure or the four-layer structure is repeatedly arranged,
Wherein the unit stack portion has a structure in which the first basic unit is repeatedly arranged. The method of claim 10,
The two or more kinds of basic units of (b)
A first electrode, a first electrode, a first electrode, a first separator, a second electrode, a second separator, a first electrode, and a first separator,
A third electrode, a second electrode, a second electrode, a first electrode, a first electrode, a first electrode, a second electrode, and a second separator in this order,
Wherein the unit stack portion has a structure in which the second basic unit and the third basic unit are alternately arranged. The method of claim 10,
The one kind of the basic unit (a) is provided in a plurality of groups and is divided into at least two groups having different sizes,
Wherein the unit stack portion has a structure in which one kind of basic unit bodies of (a) are stacked according to the size to form a plurality of stages. The method of claim 10,
The one kind of the basic unit (a) is divided into at least two groups having a plurality of different geometrical shapes,
Wherein the unit stack portion has a structure in which one kind of basic unit bodies of (a) are stacked according to a geometrical shape to form a plurality of stages. The method of claim 10,
Wherein the electrodes are adhered to adjacent separation membranes in each basic unit. 18. The method of claim 16,
Wherein the electrode is adhered to the adjacent separation membrane as a whole on a surface facing the adjacent separation membrane. 18. The method of claim 16,
Wherein the adhesion between the electrode and the separation membrane is an adhesion by applying pressure to the electrode and the adjacent separation membrane or by applying pressure and heat to the electrode and the adjacent separation membrane. 18. The method of claim 16,
Wherein an adhesion force between the electrode and the adjacent separation membrane in the basic unit body is greater than an adhesion force between the basic unit body in the unit body stack unit. 18. The method of claim 16,
Wherein the separation membrane comprises a porous membrane base material and a porous coating layer entirely coated on one or both sides of the membrane base material,
The coating layer is formed of a mixture of inorganic particles and binder polymers that connect and fix the inorganic particles to each other.
Wherein the electrode is bonded to the adjacent separation membrane by the coating layer. The method of claim 20,
Wherein the inorganic particles form a densely packed structure to form interstitial volumes between the inorganic particles as a whole in the coating layer and form a pore structure in the coating layer by the interstitial volume defined by the inorganic particles. Is formed on the surface of the electrode assembly. The method of claim 10,
The unit stack may further include a first auxiliary unit stacked on a terminal electrode, which is an electrode located at the uppermost or bottommost position,
When the terminal electrode is an anode, the first auxiliary unit body is formed by sequentially stacking a separation membrane, a cathode, a separation membrane and an anode from the terminal electrode,
Wherein when the terminal electrode is a cathode, the first auxiliary unit body is formed by sequentially stacking a separation membrane and an anode from the terminal electrode. 23. The method of claim 22,
Wherein the positive electrode of the first auxiliary unit body comprises:
Collecting house; And
And an active material coated on only one surface of the current collector facing the basic unit. The method of claim 10,
The unit stack may further include a second auxiliary unit stacked on a terminal separation membrane, which is a separation membrane located at the uppermost or bottommost position,
When the electrode in contact with the terminal separator in the basic unit body is an anode, the second auxiliary unit body is formed by laminating a cathode, a separator and an anode sequentially from the terminal separator,
Wherein the second auxiliary unit body is formed as an anode when the electrode adjacent to the terminal separation membrane in the basic unit body is a cathode. 27. The method of claim 24,
Wherein the positive electrode of the second auxiliary unit body comprises:
Collecting house; And
And an active material coated on only one surface of the current collector facing the basic unit. The method of claim 10,
The unit stack may further include a first auxiliary unit stacked on a terminal electrode, which is an electrode located at the uppermost or bottommost position,
Wherein when the terminal electrode is an anode, the first auxiliary unit body is formed by sequentially stacking a separation membrane and a cathode from the terminal electrode,
Wherein when the terminal electrode is a cathode, the first auxiliary unit body is formed by sequentially stacking a separation membrane, an anode, a separation membrane, and a cathode from the terminal electrode. 27. The method of claim 26,
Wherein the first auxiliary unit further comprises a separation membrane on the outer side of the cathode. The method of claim 10,
The unit stack may further include a second auxiliary unit stacked on a terminal separation membrane, which is a separation membrane located at the uppermost or bottommost position,
The second auxiliary unit body is formed as a cathode when the electrode in contact with the terminal separation membrane in the basic unit body is an anode,
Wherein the second auxiliary unit body is formed by sequentially stacking an anode, a separator and a cathode from the terminal separator when the electrode adjacent to the separator in the basic unit is a cathode. 29. The method of claim 28,
Wherein the second auxiliary unit further comprises a separation membrane on the outer side of the cathode. The method of claim 10,
The unit stack may further include a second auxiliary unit stacked on a terminal separation membrane, which is a separation membrane located at the uppermost or bottommost position,
Wherein the second auxiliary unit is formed by stacking a first anode, a separator, a cathode, a separator and a second anode in order from the terminal separator when the electrode adjacent to the separator in the basic unit is a cathode. 32. The method of claim 30,
And a second anode of the second auxiliary unit body,
Collecting house; And
And an active material coated on only one side of the current collector facing the basic unit. The method of claim 10,
The unit stack may further include a second auxiliary unit stacked on a terminal separation membrane, which is a separation membrane located at the uppermost or bottommost position,
Wherein the second auxiliary unit is formed by stacking a first cathode, a separator, a cathode, a separator, and a second cathode in order from the terminal separator when the electrode adjacent to the separator in the basic unit is an anode.

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