KR102616196B1 - Battery cell and battery module including the same - Google Patents

Abstract

A battery cell according to an embodiment of the present invention includes a battery case including a sealing portion in which an electrode assembly is mounted in a receiving portion and an outer periphery of the structure is sealed by heat fusion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case via the sealing portion; and a lead film located in a portion corresponding to the sealing portion at least one of the upper and lower portions of the electrode lead, wherein the lead film discharges gas extending from the inside of the battery case toward the outside of the battery case. A portion is formed, and the gas discharge portion is open toward the inside of the battery case.

Description

Battery cells and battery modules containing them {BATTERY CELL AND BATTERY MODULE INCLUDING THE SAME}

The present invention relates to a battery cell and a battery module including the same, and more specifically, to a battery cell and a battery module including the same with improved external emissions of gas generated inside the battery cell.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are receiving much attention as an energy source for not only mobile devices such as mobile phones, digital cameras, laptops, and wearable devices, but also power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

Depending on the shape of the battery case, these secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is built into a cylindrical or square metal can, and pouch-type batteries in which the electrode assembly is built in a pouch-shaped case of aluminum laminate sheet. do. Here, the electrode assembly built into the battery case is a power generating element capable of charging and discharging consisting of a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode, and a separator is formed between the positive electrode and the negative electrode in the form of a long sheet coated with an active material. It is classified into a jelly-roll type in which a plurality of anodes and cathodes are interposed and wound, and a stack type in which multiple anodes and cathodes are sequentially stacked with a separator interposed between them.

Among these, in particular, the usage of pouch-type batteries, which have a stacked or stacked/folded electrode assembly built into a pouch-type battery case of aluminum laminated sheets, is gradually increasing due to low manufacturing costs, small weight, and easy deformation. It is increasing.

Figure 1 is a top view of a conventional battery cell. Figure 2 is a cross-sectional view taken along the a-a' axis in Figure 1. Referring to Figures 1 and 2, the electrode assembly 11 of a conventional battery cell 10 is mounted on the receiving part 21, and includes a sealing part 25 whose outer periphery is sealed by heat fusion. Includes a battery case (20). Here, it includes an electrode lead 30 protruding outward from the battery case 20 via the sealing part 25, and a lead film 40 is formed between the upper and lower parts of the electrode lead 30 and the sealing part 25. ) is located.

However, as the energy density of battery cells increases recently, there is a problem that the amount of gas generated inside the battery cell also increases. In the case of the conventional battery cell 10, there are no parts that can discharge the gas generated inside the battery cell, so the battery cell may experience venting due to gas generation. In addition, moisture can penetrate into battery cells damaged by venting, which can cause side reactions, reduce battery performance, and generate additional gas. Accordingly, the need to develop battery cells with improved external emissions of gases generated inside the battery cell is increasing.

The problem to be solved by the present invention is to provide a battery cell with improved external emissions of gas generated inside the battery cell and a battery module including the same.

The problem to be solved by the present invention is not limited to the above-mentioned problems, and problems not mentioned can be clearly understood by those skilled in the art from this specification and the attached drawings. .

A battery cell according to an embodiment of the present invention includes a battery case including a sealing portion in which an electrode assembly is mounted in a receiving portion and an outer periphery of the structure is sealed by heat fusion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case via the sealing portion; and a lead film located in a portion corresponding to the sealing portion at least one of the upper and lower portions of the electrode lead, wherein the lead film discharges gas extending from the inside of the battery case toward the outside of the battery case. A portion is formed, and the gas discharge portion is open toward the inside of the battery case.

The front and both sides of the gas discharge unit may be closed based on the protruding direction of the electrode lead.

It may further include an internal layer covering at least a portion of the surface of the gas discharge unit.

The material forming the inner layer has a higher melting point than the material forming the lead film and may not react with the electrolyte solution.

The lead film may include a polyolefin-based material, and the inner layer may include at least one of polyolefin-based, fluorine-based, and porous ceramic-based materials.

The lead film may have a wider width than the electrode lead.

The lead film may have a length greater than the length of the sealing part and a length less than the length of the electrode lead.

The gas discharge portion may have a wider width than the electrode lead.

The lead film may include a first lead film and a second lead film, the first lead film may be located on an upper part of the electrode lead, and the second lead film may be located on a lower part of the electrode lead.

The electrode lead may be positioned between the first lead film and the second lead film, and the first lead film and the second lead film may be connected to each other.

An end of the gas discharge portion formed in the lead film may be located outside the outer surface of the battery case.

An end of the gas discharge portion that is open toward the inside of the battery case may be located inside the inner surface of the battery case.

A battery module according to another embodiment of the present invention may include the above-described battery cell.

According to embodiments, the present invention provides a battery cell including an electrode lead to which a lead film with a maximized penetration area is attached and a battery module including the same, so that the external emission of gas generated inside the battery cell can be improved. there is.

The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by those skilled in the art from this specification and the attached drawings.

Figure 1 is a top view of a conventional battery cell.
FIG. 2 is a cross-sectional view taken along the a-a' axis in FIG. 1.
Figure 3 is a top view of a battery cell according to this embodiment.
Figure 4 is a perspective view of an electrode lead included in the battery cell of Figure 3.
Figure 5 is a cross-sectional view taken along the c-c' axis in Figure 4.
Figure 6 is a cross-sectional view taken along the d-d' axis in Figure 4.
Figure 7 is a cross-sectional view taken along the b-b' axis in Figure 3.
Figure 8 is a diagram showing the flow of gas generated inside the battery cell in Figure 7 being discharged to the outside.
Figure 9 is a diagram showing a cross section of a battery cell according to Experimental Example 1.
Figure 10 is a diagram showing the results of measuring the gas pressure within the battery cell according to Experimental Example 2.

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

In order to clearly explain the present invention, parts that are not relevant to the description are omitted, and identical or similar components are assigned the same reference numerals throughout the specification.

In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, so the present invention is not necessarily limited to what is shown. In the drawing, the thickness is enlarged to clearly express various layers and areas. And in the drawings, for convenience of explanation, the thicknesses of some layers and regions are exaggerated.

In addition, throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

In addition, throughout the specification, when referring to “on a plane,” this means when the target portion is viewed from above, and when referring to “in cross section,” this means when a cross section of the target portion is cut vertically and viewed from the side.

Below, the pouch battery cell 100 according to an embodiment of the present invention will be described. However, the description here will be based on one side of the two sides of the pouch battery cell 100, but it is not necessarily limited to this, and the other side may also be explained with the same or similar content.

Figure 3 is a top view of a battery cell according to this embodiment.

Referring to FIG. 3, the battery cell 100 according to this embodiment includes a battery case 200, an electrode lead 300, and a lead film 400.

The battery case 200 includes a sealing portion 250 in which the electrode assembly 110 is mounted in the storage portion 210 and the outer periphery of the battery case is sealed by heat fusion. The battery case 200 may be a laminate sheet including a resin layer and a metal layer. More specifically, the battery case 200 is made of a laminated sheet and may be composed of an outer resin layer forming the outermost layer, a barrier metal layer to prevent penetration of substances, and an inner resin layer for sealing.

Additionally, the electrode assembly 110 may have a jelly-roll type (rolled type), stack type (laminated type), or composite type (stacked/folded type) structure. More specifically, the electrode assembly 110 may be composed of an anode, a cathode, and a separator disposed between them.

Hereinafter, the description will focus on the electrode lead 300 and the lead film 400.

Figure 4 is a perspective view of an electrode lead included in the battery cell of Figure 3.

Referring to Figures 3 and 4, the electrode lead 300 is electrically connected to the electrode tab (not shown) included in the electrode assembly 110, and is connected to the battery case 200 via the sealing part 250. It protrudes outward. Additionally, the lead film 400 is located in a portion corresponding to the sealing portion 250 at least one of the upper and lower portions of the electrode lead 300. Accordingly, the lead film 400 can prevent short circuits from occurring in the electrode lead 300 during heat fusion and improve the sealing properties of the sealing portion 250 and the electrode lead 300.

Additionally, the lead film 400 may have a wider width than the electrode lead 300. The lead film may have a length greater than the length of the sealing part and a length less than the length of the electrode lead. Accordingly, the lead film 400 can prevent the side of the electrode lead 300 from being exposed to the outside without interfering with the electrical connection of the electrode lead 300.

In addition, the lead film 400 includes a first lead film and a second lead film, the first lead film is located on the upper part of the electrode lead 300, and the second lead film is located on the lower part of the electrode lead 300. It can be located in . At this time, the electrode lead 300 is heat-sealed together with the sealing portion 250 while positioned between the first lead film and the second lead film, so that the first lead film and the second lead film are connected to each other. It may be.

Accordingly, the lead film 400 can prevent the side surface of the electrode lead 300 from being exposed to the outside while improving the sealing properties of the sealing portion 250 and the electrode lead 300.

Figure 5 is a cross-sectional view taken along the c-c' axis in Figure 4. Figure 6 is a cross-sectional view taken along the d-d' axis in Figure 4. Figure 7 is a cross-sectional view taken along the b-b' axis in Figure 3.

Referring to FIGS. 5 to 7, the lead film 400 is formed with a gas discharge portion 450 extending from the inside of the battery case 200 toward the outside of the battery case 200, and the gas discharge portion 450 ) is open toward the inside of the battery case 200. Additionally, the front and both sides of the gas discharge portion 450 may be closed based on the protruding direction of the electrode lead 300. Here, the gas discharge portion 450 may refer to a portion of the lead film 400 in which the remaining sides, excluding the side open toward the inside of the battery case 200, are non-adhered to each other. Additionally, the gas discharge portion 450 may have a wider width than the electrode lead 300.

Accordingly, the lead film 400 allows gas generated inside the battery case 200 to flow within the gas discharge unit 450. Additionally, when the pressure of the lead film 400 exceeds a predetermined level, gas generated inside the battery case 200 may pass through the gas discharge unit 450 and be discharged to the outside. In addition, the lead film 400 can maximize the gas permeation area through the gas discharge portion 450, allowing a large amount of gas to be discharged.

Additionally, the lead film 400 may further include an internal layer 410 covering at least a portion of the surface of the gas discharge portion 450. More preferably, the inner layer 410 may cover the entire surface of the gas outlet 450. Here, the inner layer 410 may be coated on the gas discharge portion 450, or may be manufactured as a separate film and attached to the gas discharge portion 450.

Accordingly, even if the lead film 400 is heat-sealed together with the sealing portion 250 while positioned on at least one of the upper and lower portions of the electrode lead 300, the gas discharge portion 450 is heat-sealed by the inner layer 410. It can be preserved in an unfused state.

More specifically, the inner layer 410 may be made of a material with a higher melting point than the material forming the lead film 400. Additionally, the inner layer 410 may be made of a material that does not react with the electrolyte solution contained in the battery case 300. As an example, the lead film 400 may include a polyolefin-based material, and the inner layer 410 may include at least one of polyolefin-based, fluorine-based, and porous ceramic-based materials. Additionally, the inner layer 410 includes a getter material, so that gas permeability can be increased while moisture permeability can be minimized. For example, the getter material may be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silica (SiO ₂ ), etc., but is not limited thereto and may react with water (H ₂ O). Any substance that can be used can be used.

Accordingly, the inner layer 410 is made of the above-described material, does not react separately with the electrolyte, and does not cause heat fusion or thermal deformation during the high-temperature heat fusion process, so the gas discharge portion 450 is left blank. It can be maintained. That is, the inner surface of the gas discharge portion 450 can be maintained in a non-adhesive state. In addition, when the gas generated within the battery case 200 flows into the gas discharge part 450, the inner surfaces of the gas discharge part 450 are spaced apart from each other, and the gas flowing inside the gas discharge part 450 flows to the outside. Can be easily discharged. In addition, the lead film 400 is made of the above-described material, so that the airtightness of the battery cell 100 can be maintained and leakage of the internal electrolyte solution can also be prevented.

Referring to FIG. 7 , the end of the gas discharge portion 450 formed in the lead film 400 may be located outside the outer surface of the battery case 200. Additionally, the end of the gas discharge portion 450 that is open toward the inside of the battery case 200 may be located inside the inner surface of the battery case 200.

Accordingly, the lead film 400 can maximize the area of the gas discharge portion 450, thereby maximizing the area of the inner layer 410 to which the gas generated inside the battery case 200 is exposed. Additionally, the penetration area of gas generated inside the battery case 200 can be maximized, allowing a large amount of gas to be discharged.

Figure 8 is a diagram showing the flow of gas generated inside the battery cell in Figure 7 being discharged to the outside.

Referring to FIGS. 5 to 8 , gas generated inside the battery cell 100 of FIG. 7 may flow toward the gas discharge portion 450 of the lead film 400. At this time, the gas discharge portion 450 may be expanded toward the top and bottom compared to FIG. 7 by the gas inside the battery cell 100. In addition, as shown in Figure 8A, when the gas inside the battery cell 100 exceeds a predetermined pressure, the gas inside the battery cell 100 may be discharged to the outside through the gas discharge unit 450.

Accordingly, compared to FIG. 2, as the gas discharge portion 450 is located on the lead film 400, the penetration area of the gas inside the battery cell 100 is also maximized, thereby reducing the gas generated inside the battery cell 100. External emissions of gas can also be maximized.

A battery module according to another embodiment of the present invention includes the battery cell described above. Meanwhile, one or more battery modules according to this embodiment may be packaged in a pack case to form a battery pack.

The battery module described above and the battery pack containing it can be applied to various devices. These devices can be applied to transportation means such as electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and can be applied to various devices that can use battery modules and battery packs containing them, which are also applicable to the present invention. falls within the scope of invention rights.

Below, the content of the present invention will be described through more specific examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

<Example>

A battery cell was manufactured including an electrode assembly mounted in a storage portion within a battery case and a sealing portion having a structure in which the outer periphery of the battery case was sealed by heat fusion. Here, the electrode tab included in the electrode assembly is electrically connected to the electrode lead, and the electrode lead protrudes outward from the battery case via the sealing portion. At this time, a lead film is attached to the upper part of the electrode lead at a position corresponding to the sealing part, and a gas discharge part extending from the inside of the battery case to the outside of the battery case is formed in the lead film.

<Comparative example>

A battery cell was manufactured in the same manner as in the example, except that a separate gas discharge portion was not formed in the lead film.

<Experimental Example 1 - CT scan image>

For the battery cell of the example, CT imaging was performed focusing on the sealing portion where the lead film and electrode leads were located, and a CT imaging image of the corresponding portion was obtained as shown in FIG. 9.

Figure 9 is a diagram showing a cross section of a battery cell according to Experimental Example 1. In the battery cell of the example, FIG. 9(a) is a CT image of a cross-section of the lead film and electrode lead before the internal pressure of the battery cell of the example increases, and FIG. 9(b) shows gas inside the battery cell of the example. This is a CT image of the cross-section of the lead film and electrode lead after injection to increase the internal pressure of the battery cell of the example.

Referring to FIG. 9(a), it is confirmed that no significant change is observed centered on the gas discharge portion formed in the lead film before the internal pressure of the battery cell of the example increases. However, as the internal pressure of the battery cell of the example increases, it can be seen that the gas discharge portions formed in the lead film are spaced apart in the vertical direction (arrow direction), as shown in FIG. 9(b).

Accordingly, as in this embodiment, when a gas discharge portion is formed in the lead film of a battery cell, when the internal pressure of the battery cell increases, the gas discharge portion is spaced apart in the vertical direction, so that the gas discharge portion inside the battery cell Gas may enter. That is, it can be confirmed that the gas discharge part included in the battery cell of this embodiment serves as a gas discharge path for the battery cell.

<Experimental Example 2 - Measurement of gas pressure within a battery cell>

For the battery cells of Examples and Comparative Examples, the gas pressure inside the battery cells was measured over time, and the results are shown in FIG. 10. In the battery cell of the example, the initial internal pressure of the battery cell is 1 atmosphere.

Figure 10 is a diagram showing the results of measuring the gas pressure within the battery cell according to Experimental Example 2.

Referring to FIG. 10, it can be seen that the initial internal pressure of the battery cell according to the comparative example is 1 atm, and the internal pressure decreases relatively little over time. In contrast, in the battery cell according to this embodiment, it can be seen that the internal pressure decreases relatively significantly over time, with the initial internal pressure being 1 atm. That is, it can be confirmed that the battery cell according to this embodiment effectively discharges the internal gas to the outside through the gas outlet formed in the lead film over time.

Accordingly, it can be seen that the battery cell according to this embodiment has a gas outlet formed in the lead film, so that when the pressure inside the battery cell increases, gas is easily discharged to the outside through the gas outlet.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims can also be made. It falls within the scope of invention rights.

100: battery cell
110: Electrode assembly
200: Battery case
210: storage unit
250: Sealing part
300: electrode lead
400: lead film
410: inner layer
450: Gas discharge unit

Claims (13)

a battery case in which the electrode assembly is mounted in a storage portion and includes a sealing portion whose outer periphery is sealed by heat fusion;
an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case via the sealing portion; and
At least one of the upper and lower portions of the electrode lead includes a lead film located in a portion corresponding to the sealing portion,
The lead film is formed with a gas discharge portion extending from the inside of the battery case toward the outside of the battery case,
The gas discharge portion is open toward the inside of the battery case,
The gas discharge portion is a battery cell that is a portion of the lead film in which surfaces other than the surface open toward the inside of the battery case are non-adhered to each other. In paragraph 1:
A battery cell in which the front and both sides of the gas outlet are closed based on the protruding direction of the electrode lead. In paragraph 2,
A battery cell further comprising an inner layer covering at least a portion of the surface of the gas discharge portion. In paragraph 3,
The material forming the inner layer has a higher melting point than the material forming the lead film and does not react with the electrolyte solution. In paragraph 4,
The lead film includes a polyolefin-based material,
The inner layer is a battery cell including at least one of polyolefin-based, fluorine-based, and porous ceramic-based materials. In paragraph 1:
The lead film is a battery cell having a wider width than the electrode lead. In paragraph 6:
The lead film is a battery cell having a length greater than the length of the sealing part and a length smaller than the length of the electrode lead. In paragraph 6:
The gas discharge portion is a battery cell having a width wider than the electrode lead. In paragraph 1:
The lead film includes a first lead film and a second lead film,
The first lead film is located on top of the electrode lead,
The second lead film is a battery cell located below the electrode lead. In paragraph 9:
The electrode lead is located between the first lead film and the second lead film, and the first lead film and the second lead film are connected to each other. In paragraph 1:
A battery cell in which an end of the gas discharge portion formed in the lead film is located outside the outer surface of the battery case. In paragraph 11:
The end of the gas discharge portion that is open toward the inside of the battery case is located inside the inner surface of the battery case. A battery module including the battery cell according to claim 1.