KR20240032665A - Secondary battery and device including the same - Google Patents

Abstract

A secondary battery according to an embodiment of the present invention includes an electrode assembly including an anode, a cathode, and a separator; a battery case storing the electrode assembly; and a protective member formed between the electrode assembly and the battery case, wherein the protective member includes a first protective layer, a second protective layer, and a modified layer formed between the first protective layer and the second protective layer. Includes absence.

Description

Secondary battery and device including the same {SECONDARY BATTERY AND DEVICE INCLUDING THE SAME}

The present invention relates to a secondary battery and a device including the same, and more specifically, to a secondary battery with improved safety and a device including the same.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. Accordingly, much research is being conducted on secondary batteries that can meet various needs.

Secondary batteries are attracting much attention as an energy source not only for mobile devices such as mobile phones, digital cameras, and laptops, but also for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

Recently, attempts have been made to apply various materials to develop secondary batteries with good performance in terms of high energy density, long lifespan, and durability. However, even in the case of secondary batteries with such improved characteristics, internal gas generation may be a problem in environments of high potential and high temperature storage. The volume inside the secondary battery may increase or decrease due to the generation of such gas. This increase or decrease in volume of the internal configuration causes pressure on other components, and the generated pressure may lead to a physical impact on other secondary battery components, which may eventually deteriorate the function of the secondary battery or cause an explosion of the secondary battery. Moreover, the energy density and operating voltage of secondary batteries are increasing due to improvements in the performance of portable electronic devices, and it is necessary to ensure safety against changes in the volume of the internal structure.

In addition, in the case of the secondary battery, self-heating occurs in an environment of high potential and high temperature storage, and there is a problem in that thermal runaway occurs due to the accumulation of the self-heating, causing explosion of the secondary battery.

Therefore, it is necessary to ensure safety against thermal runaway due to changes in volume of the internal structure and accumulation of self-heating.

The problem to be solved by the present invention is to provide a secondary battery with improved safety and a device containing 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 secondary battery according to an embodiment of the present invention includes an electrode assembly including an anode, a cathode, and a separator; a battery case storing the electrode assembly; and a protective member formed between the electrode assembly and the battery case, wherein the protective member includes a first protective layer, a second protective layer, and a modified layer formed between the first protective layer and the second protective layer. Includes absence.

When the internal temperature of the secondary battery rises, the denatured member is deformed, and the deformed denatured member may rupture the first protective layer and the second protective layer.

The deformation of the deformable member may mean that a deformable part is formed in the deformable member due to an increase in the internal temperature of the secondary battery.

When the modified member ruptures the first protective layer and the second protective layer, the deformation member may form a ruptured portion in the first protective layer and the second protective layer.

The first protective layer includes a first material layer including a first case and a first material, and the second protective layer includes a second material layer including a second case and a second material. The first material and the second material may be different materials.

The first material layer may include a curing catalyst, and the second material layer may include an adhesive.

When the first protective layer and the second protective layer are ruptured, the first material and the second material may come into contact and react with each other.

A hardened layer may be formed inside the battery case by a reaction between the first material and the second material.

The first case and the second case are low density polyethylene (LDPE, low density polyethylene), high density polyethylene (HDPE, high density polyethylene), oriented polypropylene (OPP, oriented polypropylene), and non-oriented polypropylene (CPP, casting polypropylene). , oriented nylon (ON), non-oriented nylon (CN, casting nylon), and polyethylene terephthalate (PET, polyethylene terephthalate).

The first material may include one or more materials selected from the group consisting of polyol, polyether polyol, and polyester polyol.

The second material is toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). It may contain one or more substances selected from the group consisting of.

The content ratio of the first material and the second material may be 30:70 to 70:30.

The modified member may include a shape memory alloy layer or an electroactive polymer layer.

The secondary battery may further include a piezoelectric element connected to the electroactive polymer layer.

A device according to another embodiment of the present invention includes the secondary battery described above.

According to embodiments, even if the secondary battery temperature rises due to self-heating of the secondary battery of the present invention, the protective layer is destroyed by the shape memory alloy before thermal runaway occurs, and the curing catalyst and the adhesive come into contact and react with each other, thereby forming the case. Since a hardening layer is formed on the inside, the possibility of thermal runaway is minimized and the secondary battery can be maintained in a safe state.

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.

1 is a cross-sectional view showing a secondary battery according to an embodiment of the present invention.
FIG. 2 is an enlarged view of portion A of FIG. 1 and is a cross-sectional view showing a protection member included in a secondary battery according to an embodiment of the present invention.
Figure 3 is a cross-sectional view showing the deformation of the protection member of Figure 2 due to an increase in temperature of the secondary battery.
Figure 4 is an enlarged view of part B of Figure 3.
Figure 5 is a plan view from above of a partial configuration of the secondary battery described in Figures 1 to 4 according to an embodiment of the present invention.
FIG. 6 is an enlarged view of portion A of FIG. 1 and is a cross-sectional view showing a protection member included in a secondary battery according to another embodiment of the present invention.
FIG. 7 is a cross-sectional view showing the deformation of the protection member of FIG. 6 due to an increase in temperature of the secondary battery.
FIG. 8 is a top plan view of a partial configuration of the secondary battery described in FIGS. 6 and 7 according to an embodiment of the present invention.

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.

Hereinafter, the secondary battery according to this embodiment will be described in detail with reference to the drawings.

1 is a cross-sectional view showing a secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, the secondary battery 100 according to this embodiment includes an electrode assembly 10 including an anode 11, a cathode 12, and a separator 13; a battery case 50 storing the electrode assembly 10; and a protective member 40 formed between the electrode assembly 10 and the battery case 50, where the protective member 40 includes a first protective layer 41, a second protective layer 45, and a second protective layer 45. It includes a shape memory alloy layer 43 formed between the first protective layer 41 and the second protective layer 45.

The electrode assembly 10 includes an anode 11, a cathode 12, and a separator 13 interposed between the anode 11 and the cathode 12. In addition, a positive electrode tab 21 is formed on one side of the positive electrode 11, and a negative electrode tab 22 is formed on one side of the negative electrode 12, and the positive electrode tab 21 and the negative electrode tab 22 are spaced at regular intervals. They can be placed side by side. The tabs can be connected to an external circuit by being connected to the anode lead 31 and the cathode lead 32, respectively.

Additionally, the electrode assembly 10, the positive electrode tab 21, and the negative electrode tab 22 may be sealed by a pouch-shaped battery case 50. The battery case 50 may typically be made of a laminated sheet including a resin layer and a metal layer. At this time, for electrical connection to the outside of the electrode assembly 10, a portion of the positive electrode lead 31 and the negative electrode lead 32 may be sealed by a pouch while exposed to the outside. However, the type of the battery case 50 is not limited to this and may be a rectangular or cylindrical case.

In this embodiment, it includes a protective member 40 formed between the electrode assembly 10 and the battery case 50. The protective member 40 is formed between the electrode assembly 10 and the battery case 50 as shown in FIG. 1, and may be formed on both the upper and lower parts of the electrode assembly 10, but is not limited to this and is not limited to this. It may be located corresponding to only one side of the assembly 10.

FIG. 2 is an enlarged view of portion A of FIG. 1 and is a cross-sectional view showing a protection member included in a secondary battery according to an embodiment of the present invention. Figure 3 is a cross-sectional view showing the deformation of the protection member of Figure 2 due to an increase in temperature of the secondary battery. Figure 4 is an enlarged view of part B of Figure 3. Figure 5 is a top plan view of a partial configuration of a secondary battery according to an embodiment of the present invention.

Referring to FIG. 2, the protective member 40 has a first protective layer 41, a second protective layer 45, and a shape formed between the first protective layer 41 and the second protective layer 45. It may include a memory alloy layer 43. At this time, in FIGS. 1 and 2, the first protective layer 41 is shown to be located on the battery case 50 side and the second protective layer 45 is shown to be located on the electrode assembly 10 side, but the present invention is not limited to this. The second protective layer 45 may be located on the battery case 50 side and the first protective layer 41 may be located on the electrode assembly 10 side. In addition, if it does not interfere with cell operation, the first protective layer 41 and the second protective layer are applied to the lead portion such as the positive lead 31 or the negative lead 32 or to the portion where the pouch case 50 is sealed. (45) may also be placed.

Additionally, referring to FIG. 5 , the shape memory alloy layer 43 may be formed to have a smaller area than the first and second protective layers 41 and 45 . However, although the first protective layer 41 is shown omitted in FIG. 5, it is obvious that the first protective layer 41 is formed on the top of the shape memory alloy layer 43.

At this time, referring to FIGS. 2 and 4, the first protective layer 41 includes a first case 41a and a first material layer 41b including a first material, and the second protective layer 45 may include a second case 45a and a second material layer 45b including a second material. The first material 41b and the second material 45b may be different materials.

Therefore, in FIGS. 2 and 4, the shape memory alloy layer 43 is located between the first protective layer 41 and the second protective layer 45 and is formed by the first case 41a and the second case 45a. The first material layer 41b and the second material layer 45b are separated so as not to contact each other. In this case, the first material layer 41b and the second material layer 45b do not react with each other and the secondary battery (100) operates normally.

Meanwhile, in the case of the secondary battery 100, self-heating may occur in an environment of high potential and high temperature storage, and when the internal temperature of the secondary battery 100 increases due to self-heating of the secondary battery 100, the shape memory alloy layer (43) can be modified.

3 and 4, when the internal temperature of the secondary battery 100 rises, the shape memory alloy layer 43 is deformed at a temperature before thermal runaway occurs, and the deformed shape memory alloy layer 43 is The first protective layer 41 and the second protective layer 45 may be ruptured. For example, since thermal runaway occurs at approximately 140 degrees Celsius to 150 degrees Celsius, the shape memory alloy layer 43 may operate below about 130 degrees Celsius.

At this time, the deformation of the shape memory alloy layer 43 may mean that a deformation portion 43' is formed in the shape memory alloy layer 43 due to an increase in the internal temperature of the secondary battery 100.

Specifically, shape memory alloy is a material that returns to the shape before deformation when heated above a certain temperature. Through this phenomenon, when the internal temperature of the secondary battery 100 increases, a deformed portion 43' is formed in the shape memory alloy layer 43. can be formed.

Therefore, the reason why the shape memory alloy layer 43 ruptures the first protective layer 41 and the second protective layer 45 is that the deformation portion 43' causes the first protective layer 41 and the second protective layer ( 45) may rupture. More specifically, the deformation portion 43' forms rupture portions 41a' and 45a' in the first protective layer 41 and the second protective layer 45, thereby forming the first protective layer 41 and the second protective layer 45. This may rupture the layer 45.

In particular, the ruptured portions 41a' and 45a' may be formed on the first case 41a and the second case 45a. That is, by forming the rupture portions 41a' and 45a' on the first case 41a and the second case 45a, respectively, the first material layer 41b and the second material layer 45b are each formed in the first case 41a and the second case 45a. It may be exposed to the outside of the case 41a and the second case 45b.

Therefore, when the secondary battery 100 according to this embodiment self-heats, the first protective layer 41 and the second protective layer 45 are ruptured, thereby forming the first material layer 41b and the second material layer ( 45b) can react with each other upon contact.

At this time, the first material layer 41b may include a curing catalyst, and the second material layer 45b may include an adhesive.

Therefore, a hardened layer may be formed inside the battery case 50 by a reaction between the first material layer 41a and the second material layer 45b. By strengthening the inner wall of the battery case 50 with this hardened layer, it is possible to delay the temperature rise due to self-heating, as well as delay and suppress the occurrence of thermal runaway through the delay in the temperature rise.

In order to rupture due to deformation of the shape memory alloy layer 43, the first case 41a and the second case 45a are made of low density polyethylene (LDPE, low density polyethylene) or high density polyethylene (HDPE, high density polyethylene). , oriented polypropylene (OPP, oriented polypropylene), non-oriented polypropylene (CPP, casting polypropylene), oriented nylon (ON, oriented nylon), non-oriented nylon (CN, casting nylon), polyethylene terephthalate (PET, polyethylene terephthalate) It may contain one or more substances selected from the group consisting of. The above materials are materials that can be ruptured by a predetermined pressure generated as the deformation portion 43' is formed in the shape memory alloy layer 43. Additionally, the thickness of the first case 41a and the second case 45a may be 10 μm to 50 μm. If the thickness is less than 10㎛, the first case (41a) and the second case (45a) may be destroyed even by a small impact and a hardened layer may be formed, which is not desirable. If the thickness exceeds 50㎛, it is not preferable because the first case 41a and the second case 45a are not destroyed despite deformation of the shape memory alloy layer 43 and a hardened layer cannot be formed.

Additionally, the first material layer 41b may include one or more materials selected from the group consisting of polyol, polyether polyol, and polyester polyol.

The second material layer 45b is made of toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). It may contain one or more substances selected from the group consisting of isophorone diisocyanate).

Accordingly, a compound such as polyurethane may be formed through a reaction between the first material layer 41b and the second material layer 45b to form a cured layer.

In order for the first material layer 41b and the second material layer 45b to react effectively by contact, the content ratio of the first material layer 41b and the second material layer 45b is 30:70 to 70:30. It can be.

The first material and the second material may be semi-solid materials with a viscosity in the range of 10 to 90,000 cP. If the viscosity is too low, the first material or the second material may flow out and cause a reaction even when the first case 41a and the second case 45a are not destroyed, which is undesirable, and if the viscosity is too high, the first material or the second material may flow out and cause a reaction. This is undesirable in that even if the first case 41a and the second case 45a are destroyed, a sufficient reaction does not occur between the first material and the second material, making it difficult to form a hardened layer.

In this secondary battery 100, under normal operating conditions, the first material layer 41b and the second material layer 45b are separated by the shape memory alloy layer 43 and the cases 41a and 45a, so that the cured layer Normal operation is possible without formation. In addition, when the internal temperature of the secondary battery 100 increases due to various causes under abnormal circumstances such as overcharging, high potential, or high temperature storage, the shape memory alloy layer 43 is deformed and the first material layer 41b ) and the second material layer 45b react to form a hardened layer, thereby strengthening the inner wall of the battery case 50, thereby delaying the thermal runaway phenomenon caused by an additional temperature rise, thereby improving the safety of the secondary battery. It can be improved further.

FIG. 6 is an enlarged view of portion A of FIG. 1 and is a cross-sectional view showing a protection member included in a secondary battery according to another embodiment of the present invention. FIG. 7 is a cross-sectional view showing the deformation of the protection member of FIG. 6 due to an increase in temperature of the secondary battery. FIG. 8 is a top plan view of a partial configuration of the secondary battery described in FIGS. 6 and 7 according to an embodiment of the present invention.

Referring to FIG. 6, the protective member 46 according to this embodiment includes a first protective layer 41, a second protective layer 45, and the first protective layer 41 and the second protective layer 45. It may include a metamorphic member formed in between. Instead of the shape memory alloy layer 43 described in the embodiment of FIGS. 2 to 5, the modified member may include a piezoelectric element 47 and an electroactive polymer layer 48.

According to this embodiment, at least one electroactive polymer layer 48 may be electrically and/or physically connected to the piezoelectric element 47. Referring to FIG. 8 , the piezoelectric element 47 may be in contact with the electroactive polymer layer 48 at some portions of both side surfaces and may be connected to the piezoelectric element 47 through the connecting member 49. Through this connection structure, an electrical signal generated when pressure is applied to the piezoelectric element 47 can be transmitted to the electroactive polymer layer 48 through the connection member 49.

Specifically, the pressure increases as the internal temperature of the secondary battery 100 increases and/or gas is generated, and this pressure may be transmitted to the piezoelectric element 47. When pressure is applied to the piezoelectric element 47, the electrical current generated thereby causes the electroactive polymer layer 48 to operate, and as shown in FIG. 7, the physical properties of the electroactive polymer layer 48 are increased. Deformation may occur and a deformation portion 48' may be formed in the electroactive polymer layer 48. Due to this deformation portion 48', the first protective layer 41 and the second protective layer 45 may be ruptured. The shape of the deformed portion 48' shown in FIG. 7 is an example, and the deformed portion of FIG. 7 ( The shape of 48') is deformable.

Except for the description of the electroactive polymer layer 48 described above, all of the information described in the embodiment of FIGS. 2 to 5 is applicable to the present embodiment.

The secondary battery according to this embodiment described above can be applied to various devices. Specifically, it can be applied to transportation means such as electric bicycles, electric vehicles, and hybrids, but is not limited to this and can be applied to various devices that can use secondary batteries.

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 are also possible. falls within the scope of rights.

10: Electrode assembly
21, 22: positive tab, negative tab
31, 32: positive lead, negative lead
40: protection member
41: first protective layer
43: Shape memory alloy layer
45: second protective layer
47: Piezoelectric element
48: Electroactive polymer layer
50: battery case
100: secondary battery

Claims (15)

An electrode assembly including an anode, a cathode, and a separator;
a battery case storing the electrode assembly; and
It includes a protective member formed between the electrode assembly and the battery case,
The protective member is,
first protective layer,
a second protective layer, and
A secondary battery comprising a denatured member formed between the first protective layer and the second protective layer. In paragraph 1:
When the internal temperature of the secondary battery rises, the denatured member is deformed,
A secondary battery in which the deformed denatured member ruptures the first protective layer and the second protective layer. In paragraph 2,
The deformation of the deformable member is
A secondary battery in which a deformation part is formed in the denatured member due to an increase in the internal temperature of the secondary battery. In paragraph 3,
The reason why the modified member ruptures the first protective layer and the second protective layer is,
A secondary battery wherein the deformation portion forms a rupture portion in the first protective layer and the second protective layer. In paragraph 4,
The first protective layer includes a first case and a first material layer including a first material, and the second protective layer includes a second material layer including a second case and a second material,
A secondary battery wherein the first material and the second material are different materials. In paragraph 5,
The first material includes a curing catalyst,
A secondary battery wherein the second material includes an adhesive. In paragraph 5,
A secondary battery in which the first material and the second material come into contact and react with each other when the first protective layer and the second protective layer are ruptured. In paragraph 5,
A secondary battery in which a cured layer is formed inside the battery case by a reaction between the first material and the second material. In paragraph 5,
The first case and the second case are low density polyethylene (LDPE, low density polyethylene), high density polyethylene (HDPE, high density polyethylene), oriented polypropylene (OPP, oriented polypropylene), and non-oriented polypropylene (CPP, casting polypropylene). , a secondary battery containing one or more materials selected from the group consisting of oriented nylon (ON), non-oriented nylon (CN, casting nylon), and polyethylene terephthalate (PET). In paragraph 5,
A secondary battery wherein the first material includes one or more materials selected from the group consisting of polyol, polyether polyol, and polyester polyol. In paragraph 5,
The second material is toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). A secondary battery comprising one or more materials selected from the group consisting of. In paragraph 5,
A secondary battery wherein the content ratio of the first material and the second material is 30:70 to 70:30. In paragraph 1:
A secondary battery wherein the modified member includes a shape memory alloy layer or an electroactive polymer layer. In paragraph 3,
A secondary battery further comprising a piezoelectric element connected to the electroactive polymer layer. A device comprising a secondary battery according to claim 1.