Rechargeable batteries and devices containing them

Abstract

A secondary battery according to an embodiment of the present invention includes an electrode assembly including a positive electrode, a negative electrode, and a separator, a battery case that houses the electrode assembly, and a protective member formed between the electrode assembly and the battery case, the protective member including a first protective layer, a second protective layer, and a modified member formed between the first protective layer and the second protective layer.

Description

Technical Field

[0001] [Cross - reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0110744 filed on September 1, 2022 and Korean Patent Application No. 10 - 2023 - 0114560 filed on August 30, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference.

[0002] 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.

Background Art

[0003] As the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has been rapidly increasing. Therefore, many studies on secondary batteries that can meet various requirements have been conducted.

[0004] Secondary batteries have attracted much attention not only as an energy source for mobile devices such as mobile phones, digital cameras, and notebook computers, but also for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0005] Recently, various materials have been applied to develop secondary batteries with superior performance in terms of high energy density, long lifespan, and durability. However, even with secondary batteries possessing such improved characteristics, the generation of internal gases in high-potential and high-temperature storage environments can become a problem. This gas generation can increase or decrease the internal volume of the secondary battery. Such increases or decreases in the volume of internal components can induce pressure on other components, and this pressure can lead to physical shock to other secondary battery components, potentially resulting in a decrease in the battery's function or even an explosion. Furthermore, with the increasing performance of portable electronic devices, the energy density and operating voltage of secondary batteries are rising, making it necessary to ensure safety against such changes in the internal volume.

[0006] Furthermore, in the case of the aforementioned secondary battery, self-heating occurs in high-potential and high-temperature storage environments, and the accumulation of this self-heating can lead to thermal runaway, which can trigger an explosion of the secondary battery.

[0007] Therefore, it is necessary to ensure safety against thermal runaway caused by volume changes in the internal components and the accumulation of self-heating. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The problem that this invention aims to solve is to provide a secondary battery with improved safety and a device containing the same.

[0009] The problems that this invention aims to solve are not limited to those described above, and any problems not mentioned should be clearly understood by a person with ordinary skill in the art to which this invention pertains from this specification and the accompanying drawings. [Means for solving the problem]

[0010] A secondary battery according to one embodiment of the present invention includes an electrode assembly comprising a positive electrode, a negative electrode, and a separator membrane; a battery case housing the electrode assembly; and a protective member formed between the electrode assembly and the battery case, wherein the protective member comprises a first protective layer, a second protective layer, and a modified member formed between the first protective layer and the second protective layer.

[0011] When the internal temperature of the secondary battery rises, the modified member deforms, and the deformed modified member can cause the first protective layer and the second protective layer to rupture.

[0012] The deformation of the modified member may occur when a deformed portion is formed in the modified member due to an increase in the internal temperature of the secondary battery.

[0013] The deformation of the modified member may cause the first protective layer and the second protective layer to rupture, even if the deformation portion forms a rupture portion in the first protective layer and the second protective layer.

[0014] The first protective layer includes a first material layer containing a first case and a first substance, and the second protective layer includes a second material layer containing a second case and a second substance, wherein the first substance and the second substance may be different substances from each other.

[0015] The first material layer may contain a curing catalyst, and the second material layer may contain an adhesive.

[0016] The first protective layer and the second protective layer may rupture, causing the first substance and the second substance to come into contact and react with each other.

[0017] A hardened layer may be formed on the inside of the battery case by the reaction between the first substance and the second substance.

[0018] The first and second cases may contain one or more substances selected from the group consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), oriented polypropylene (OPP), casting polypropylene (CPP), oriented nylon (ON), casting nylon (CN), and polyethylene terephthalate (PET).

[0019] The first substance may include one or more substances selected from the group consisting of polyols, polyether polyols, and polyester polyols.

[0020] The second substance may include one or more substances selected from the group consisting of toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0021] The content ratio of the first substance and the second substance may be between 30:70 and 70:30.

[0022] The modified member may include a shape memory alloy layer or an electroactive polymer layer.

[0023] The secondary battery may further include a piezoelectric element connected to the electroactive polymer layer.

[0024] The device according to another embodiment of the present invention includes the secondary battery described above.

Effects of the Invention

[0025] According to the embodiment, even if the temperature of the secondary battery of the present invention rises due to self-heating of the secondary battery, before thermal runaway occurs, the protective layer is broken by the shape memory alloy, and the curing catalyst and the adhesive come into contact with each other and react with each other, thereby forming a cured layer inside the case. Therefore, the possibility of thermal runaway can be minimized and the secondary battery can be maintained in a safe state.

[0026] The effects of the present invention are not limited to the effects described above, and the effects not mentioned should be clearly understood by those having ordinary knowledge in the technical field to which the present invention pertains in this specification and the accompanying drawings.

Brief Description of the Drawings

[0027] [Figure 1] It is a cross-sectional view showing a secondary battery according to an embodiment of the present invention. [Figure 2] It is an enlarged view of part A in FIG. 1 and is a cross-sectional view showing a protective member included in the secondary battery according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view showing the state in which the protective member in FIG. 2 is deformed due to an increase in the temperature of the secondary battery. [Figure 4] It is an enlarged view of part B in FIG. ۳. [Figure 5] It is a plan view of a part of the configuration of the secondary battery described in FIGS. 1 to Four according to an embodiment of the present invention, as viewed from above. [Figure 6] It is an enlarged view of part A in FIG. 1 and is a cross-sectional view showing a protective member included in the secondary battery according to another embodiment of the present invention. [Figure 7] It is a cross-sectional view showing the state in which the protective member in FIG. 6 is deformed due to an increase in the temperature of the secondary battery. [Figure 8]Figures 6 and 7 show a top view of a part of the configuration of a secondary battery described in one embodiment of the present invention. [Modes for carrying out the invention]

[0028] The following describes various embodiments of the present invention in detail, with reference to the attached drawings, so that those with ordinary skill in the art to which the present invention pertains can easily implement them. The present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0029] To clearly explain the present invention, irrelevant parts have been omitted, and the same or similar reference numerals have been used throughout the specification for identical or similar components.

[0030] Furthermore, the dimensions and thicknesses of each component shown in the drawings are arbitrary for the sake of explanation and are not necessarily limited to those shown in the present invention. The thicknesses are shown enlarged in the drawings to clearly represent various layers and regions. In addition, the thicknesses of some layers and regions are exaggerated in the drawings for the sake of explanation.

[0031] Furthermore, when a specification states that a certain part "includes" a certain component, this means that, unless otherwise stated, it does not exclude other components, but rather can further include other components.

[0032] Furthermore, throughout the specification, "on a plane" means when the subject is viewed from above, and "on a cross-section" means when the subject is viewed from the side of a cross-section obtained by cutting the subject perpendicularly.

[0033] In the following section, the secondary battery according to this embodiment will be described in detail with reference to the drawings.

[0034] Figure 1 is a cross-sectional view showing a secondary battery according to one embodiment of the present invention.

[0035] Referring to Figure 1, the secondary battery 100 according to this embodiment includes an electrode assembly 10 including a positive electrode 11, a negative electrode 12, and a separator membrane 13, a battery case 50 housing the electrode assembly 10, and a protective member 40 formed between the electrode assembly 10 and the battery case 50. The protective member 40 includes a first protective layer 41, a second protective layer 45, and a shape memory alloy layer 43 formed between the first protective layer 41 and the second protective layer 45.

[0036] The electrode assembly 10 includes a positive electrode 11, a negative electrode 12, and a separator membrane 13 interposed between the positive electrode 11 and the negative electrode 12. 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 may be arranged side by side with a certain distance between them. The tabs may be connected to an external circuit by being connected to a positive electrode lead 31 and a negative electrode lead 32, respectively.

[0037] Furthermore, the electrode assembly 10, the positive electrode tab 21, and the negative electrode tab 22 may be sealed by a pouch-type battery case 50. The battery case 50 may typically consist of a laminate sheet containing a resin layer and a metal layer. In this case, for electrical connection with the outside of the electrode assembly 10, a portion of the positive electrode lead 31 and the negative electrode lead 32 may be exposed to the outside while sealed by the pouch. However, the type of battery case 50 is not limited to this, and it may also be a rectangular or cylindrical case.

[0038] In this embodiment, a protective member 40 is 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 Figure 1, and may be formed on both the upper and lower parts of the electrode assembly 10, but is not limited to this, and may be positioned corresponding to only one side of the electrode assembly 10.

[0039] Figure 2 is an enlarged view of portion A in Figure 1, and is a cross-sectional view showing a protective member included in a secondary battery according to one embodiment of the present invention. Figure 3 is a cross-sectional view showing how the protective member in Figure 2 is deformed due to a temperature rise in the secondary battery. Figure 4 is an enlarged view of portion B in Figure 3. Figure 5 is a top view of a part of the configuration of a secondary battery according to one embodiment of the present invention.

[0040] Referring to Figure 2, the protective member 40 may include a first protective layer 41, a second protective layer 45, and a shape memory alloy layer 43 formed between the first protective layer 41 and the second protective layer 45. In this case, Figures 1 and 2 show the first protective layer 41 located on the battery case 50 side and the second protective layer 45 located on the electrode assembly 10 side, but it is not limited to this, and the second protective layer 45 may be located on the battery case 50 side and the first protective layer 41 on the electrode assembly 10 side. Furthermore, the first protective layer 41 and the second protective layer 45 may be arranged on the lead side, such as the positive electrode lead 31 or the negative electrode lead 32, or in the part where the pouch case (battery case 50) is sealed, as long as it does not interfere with cell driving.

[0041] Furthermore, referring to Figure 5, the shape memory alloy layer 43 may be formed to have a smaller area than the first protective layer 41 and the second protective layer 45. However, although the first protective layer 41 is omitted in Figure 5, it is obvious that the first protective layer 41 is formed on top of the shape memory alloy layer 43.

[0042] Referring to Figures 2 and 4, the first protective layer 41 may include a first case 41a and a first material layer 41b containing a first substance, and the second protective layer 45 may include a second case 45a and a second material layer 45b containing a second substance. The first substance 41b and the second substance 45b may be different substances from each other.

[0043] Therefore, in Figures 2 and 4, the shape memory alloy layer 43 is located between the first protective layer 41 and the second protective layer 45, and the first material layer 41b and the second material layer 45b are separated by the first case 41a and the second case 45a so as not to come into contact with 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.

[0044] On the other hand, in the case of the secondary battery 100, self-heating may occur in high-potential and high-temperature storage environments, and when the internal temperature of the secondary battery 100 rises due to such self-heating, the shape memory alloy layer 43 may be deformed.

[0045] Referring to Figures 3 and 4, when the internal temperature of the secondary battery 100 rises, the shape memory alloy layer 43 deforms at a temperature before thermal runaway occurs, and the deformed shape memory alloy layer 43 can cause the first protective layer 41 and the second protective layer 45 to rupture. For example, since thermal runaway occurs at approximately 140 to 150 degrees Celsius, the shape memory alloy layer 43 can operate at approximately 130 degrees Celsius or below.

[0046] In this case, the deformation of the shape memory alloy layer 43 may occur when a deformed portion 43' is formed in the shape memory alloy layer 43 due to an increase in the internal temperature of the secondary battery 100.

[0047] Specifically, shape memory alloys are materials that return to their original shape when heated above a certain temperature, and through this phenomenon, a deformed portion 43' can be formed in the shape memory alloy layer 43 when the internal temperature of the secondary battery 100 rises.

[0048] Therefore, the rupture of the first protective layer 41 and the second protective layer 45 by the shape memory alloy layer 43 may also occur if the deformed portion 43' ruptures the first protective layer 41 and the second protective layer 45. More specifically, the deformed portion 43' may rupture the first protective layer 41 and the second protective layer 45 by forming rupture portions 41a' and 45a' in the first protective layer 41 and the second protective layer 45.

[0049] In particular, the rupture 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, the first material layer 41b and the second material layer 45b may be exposed to the outside of the first case 41a and the second case 45a, respectively.

[0050] Therefore, when the secondary battery 100 according to this embodiment generates its own heat, the first protective layer 41 and the second protective layer 45 rupture, causing the first material layer 41b and the second material layer 45b to come into contact and react with each other.

[0051] In this case, the first material layer 41b may contain a curing catalyst, and the second material layer 45b may contain an adhesive.

[0052] Therefore, a hardened layer may be formed on the inside of the battery case 50 by the reaction between the first material layer 41b and the second material layer 45b. By strengthening the inner wall of the battery case 50 with such a hardened layer, it is possible not only to delay the temperature rise due to self-heating, but also to delay and suppress the occurrence of thermal runaway through the delay in temperature rise.

[0053] In order to rupture due to the deformation of the shape memory alloy layer 43, the first case 41a and the second case 45a may contain one or more materials selected from the group consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), oriented polypropylene (OPP), casting polypropylene (CPP), oriented nylon (ON), casting nylon (CN), and polyethylene terephthalate (PET). The material is capable of rupturing by a predetermined pressure generated by the formation of a deformed portion 43' in the shape memory alloy layer 43. The thickness of the first case 41a and the second case 45a may be between 10 μm and 50 μm. If the thickness is less than 10 μm, the first case 41a and the second case 45a may break even with a small impact, and a hardened layer may be formed, which is undesirable. If the thickness exceeds 50 μm, the first case 41a and the second case 45a do not break despite the deformation of the shape memory alloy layer 43, and a hardened layer is not formed, which is undesirable.

[0054] Furthermore, the first material layer 41b may contain one or more substances selected from the group consisting of polyol, polyether polyol, and polyester polyol.

[0055] The second material layer 45b may contain one or more substances selected from the group consisting of toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0056] Therefore, a compound such as polyurethane is formed by the reaction between the first material layer 41b and the second material layer 45b, and a cured layer can be formed.

[0057] The content ratio of the first material layer 41b to the second material layer 45b may be between 30:70 and 70:30 in order for the first material layer 41b and the second material layer 45b to effectively trigger a reaction upon contact.

[0058] The first and second substances may be semi-solid substances with a viscosity in the range of 10 to 90,000 cP. If the viscosity is excessively low, the first or second substance may flow out and a reaction may occur even if the first case 41a and the second case 45a are not destroyed, which is undesirable. If the viscosity is excessively high, even if the first case 41a and the second case 45a are destroyed, a sufficient reaction may not occur between the first and second substances, making it difficult to form a hardened layer, which is also undesirable.

[0059] In such a 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, allowing for normal operation without the formation of a hardened layer. However, in abnormal conditions such as overcharging, high potential, or high-temperature storage environments, if the internal temperature of the secondary battery 100 rises due to various causes, the shape memory alloy layer 43 deforms, causing the first material layer 41b and the second material layer 45b to come into contact and react to form a hardened layer. This strengthens the inner wall of the battery case 50, delaying thermal runaway phenomena due to additional temperature increases and further improving the safety of the secondary battery.

[0060] Figure 6 is an enlarged view of portion A in Figure 1, and is a cross-sectional view showing a protective member included in a secondary battery according to another embodiment of the present invention. Figure 7 is a cross-sectional view showing how the protective member in Figure 6 is deformed due to a temperature rise in the secondary battery. Figure 8 is a top view of a part of the configuration of the secondary battery described in Figures 6 and 7 according to one embodiment of the present invention.

[0061] Referring to Figure 6, the protective member 46 according to this embodiment may include a first protective layer 41, a second protective layer 45, and a modified member formed between the first protective layer 41 and the second protective layer 45. Instead of the shape memory alloy layer 43 described in the embodiments of Figures 2 to 5, the modified member may include a piezoelectric element 47 and an electroactive polymer layer 48.

[0062] According to this embodiment, at least one electroactive polymer layer 48 can be electrically and / or physically connected to the piezoelectric element 47. Referring to Figure 8, the piezoelectric element 47 can be in contact with the electroactive polymer layer 48 at a portion of both sides and can be connected to the piezoelectric element 47 through a connecting member 49. Through such a connecting structure, the electrical signal generated when pressure is applied to the piezoelectric element 47 can be transmitted to the electroactive polymer layer 48 through the connecting member 49.

[0063] Specifically, the internal temperature of the secondary battery 100 rises and / or gas is generated, causing the pressure to increase, and this pressure may be transmitted to the piezoelectric element 47. When pressure is applied to the piezoelectric element 47, the resulting current activates the electroactive polymer layer 48, and as an example, as shown in Figure 7, physical deformation of the electroactive polymer layer 48 may occur, forming a deformed portion 48' in the electroactive polymer layer 48. Such a deformed portion 48' may cause the first protective layer 41 and the second protective layer 45 to rupture. The shape of the deformed portion 48' shown in Figure 7 is just one example, and the shape of the deformed portion 48' in Figure 7 can be changed by the contraction and expansion of the electroactive polymer layer 48 due to ion movement and diffusion in response to changes in the external voltage.

[0064] Except for the explanation regarding the electroactive polymer layer 48 described above, all of the information described in the examples in Figures 2 to 5 is applicable to these examples as well.

[0065] The secondary battery according to the embodiment described above can be applied to a variety of devices. Specifically, it can be applied to means of transportation such as electric bicycles, electric vehicles, and hybrids, but is not limited to these, and can be applied to a variety of devices in which secondary batteries are used.

[0066] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements by those skilled in the art, using the basic concepts of the present invention as defined in the following claims, also fall within the scope of the present invention. [Explanation of symbols]

[0067] 10: Electrode assembly 21: Positive Tab 22: Negative electrode tab 31: Positive lead 32: Negative lead 40: Protective component 41:1st 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

1. An electrode assembly including a positive electrode, a negative electrode, and a separator membrane, A battery case for housing the electrode assembly, Includes a protective member formed between the electrode assembly and the battery case, The protective member is The first protective layer, The second protective layer, A secondary battery comprising a modified member formed between the first protective layer and the second protective layer, The first protective layer comprises a first substance, and the second protective layer comprises a second substance. The first substance comprises a curing catalyst, The second substance includes an adhesive, When the internal temperature of the secondary battery rises, the modified member is deformed. The deformed modified member causes the first protective layer and the second protective layer to rupture. A secondary battery in which a hardened layer is formed on the inside of the battery case by a reaction between the first substance and the second substance.

2. An electrode assembly comprising a positive electrode, a negative electrode, and a separator membrane, A battery case for housing the electrode assembly, Includes a protective member formed between the electrode assembly and the battery case, The protective member is The first protective layer, The second protective layer, A secondary battery comprising a modified member formed between the first protective layer and the second protective layer, The first protective layer includes a first material layer containing a first case and a first substance, and the second protective layer includes a second material layer containing a second case and a second substance. The first substance and the second substance are different substances from each other. The modified member includes a shape memory alloy layer or an electroactive polymer layer. When the internal temperature of the secondary battery rises, the modified member is deformed. The deformed modified member causes the first protective layer and the second protective layer to rupture. A secondary battery in which a hardened layer is formed on the inside of the battery case by a reaction between the first substance and the second substance.

3. The deformation of the modified member is The secondary battery according to claim 1 or 2, wherein a deformed portion is formed in the modified member due to an increase in the internal temperature of the secondary battery.

4. The modified member causes the first protective layer and the second protective layer to rupture. The secondary battery according to claim 3, wherein the deformed portion forms a rupture portion in the first protective layer and the second protective layer.

5. The first protective layer includes a first material layer containing a first case and a first substance, and the second protective layer includes a second material layer containing a second case and a second substance. The secondary battery according to claim 1, wherein the first substance and the second substance are different substances from each other.

6. The first substance comprises a curing catalyst, The secondary battery according to claim 2, wherein the second substance includes an adhesive.

7. The secondary battery according to claim 1 or 2, wherein the first protective layer and the second protective layer rupture, causing the first substance and the second substance to come into contact and react with each other.

8. The secondary battery according to claim 2 or 5, wherein the first case and the second case each contain one or more materials selected from the group consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), oriented polypropylene (OPP), unoriented polypropylene (CPP), oriented nylon (ON), unoriented nylon (CN), and polyethylene terephthalate (PET).

9. The secondary battery according to claim 2 or 5, wherein the first substance comprises one or more substances selected from the group consisting of polyol, polyether polyol, and polyester polyol.

10. The secondary battery according to claim 2 or 5, wherein the second substance comprises one or more substances selected from the group consisting of toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

11. The secondary battery according to claim 2 or 5, wherein the content ratio of the first substance and the second substance is 30:70 to 70:

30.

12. The secondary battery according to claim 1, wherein the modified member includes a shape memory alloy layer or an electroactive polymer layer.

13. The secondary battery according to claim 12, further comprising a piezoelectric element connected to the electroactive polymer layer.

14. A device comprising a secondary battery according to claim 1 or 2.

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