Secondary battery and device including the same

Abstract

A secondary battery according to an embodiment of the present invention comprises: an electrode assembly including a positive electrode, a negative electrode, and a separator; a battery case in which the electrode assembly is accommodated; and a protective member formed between the electrode assembly and the battery case, in which the protective member includes 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

[0002] This application claims the benefit of 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, the disclosures of which are incorporated herein by reference in their entirety.

[0003] The present disclosure relates to a secondary battery and a device including the secondary battery, and more particularly, to a secondary battery having improved safety and a device including the secondary battery. Background Art

[0004] As technology develops and demand for mobile devices increases, demand for secondary batteries as energy sources has been rapidly increasing. Therefore, various studies have been conducted on batteries that can meet various needs.

[0005] Secondary batteries have attracted considerable attention as energy sources for power-driven devices such as electric bicycles, electric vehicles, and hybrid electric vehicles, and for mobile devices such as mobile phones, digital cameras, and laptop computers.

[0006] In recent years, attempts have been made to apply various materials to develop secondary batteries with good performance in terms of high energy density, long life and durability. However, even in the case where the secondary battery has such improved properties, the generation of internal gas can also be the cause of problems in high potential and high temperature storage environments. Due to the generation of such gas, the volume inside the secondary battery can increase or decrease. The increase or decrease in the volume of such internal components causes pressure on other components, and the pressure generated can cause physical impact on other secondary battery components, which can eventually degrade the function of the secondary battery or cause the secondary battery to explode. In addition, due to the improvement of the performance of portable electronic devices, the energy density and operating voltage of secondary batteries are increasing, and it is necessary to ensure the safety of such internal component volume changes.

[0007] In addition, in the case of a secondary battery, self-heating occurs in a high potential and high temperature storage environment, and there is a problem that thermal runaway occurs due to accumulation of self-heat, which may cause the secondary battery to explode.

[0008] Therefore, it is necessary to ensure safety against thermal runaway due to volume changes and self-heat accumulation of internal components. Summary of the invention

[0009] Technical issues

[0010] An object of the present disclosure is to provide a secondary battery having improved safety and a device including the secondary battery.

[0011] The objects of the present disclosure are not limited to the above objects, and any other objects and advantages not mentioned herein should be clearly understood by those skilled in the art from the following description and accompanying drawings.

[0012] Technical Solution

[0013] According to an embodiment of the present disclosure, a secondary battery is provided, which includes: an electrode assembly, the electrode assembly including a positive electrode, a negative electrode and a separator; a battery case, the battery case accommodating the electrode assembly; and a protective member, the protective member being formed between the electrode assembly and the battery case, wherein the protective member includes: a first protective layer, a second protective layer, and a denaturation member, the denaturation member being formed between the first protective layer and the second protective layer.

[0014] When the internal temperature of the secondary battery increases, the deformation member is deformed, and the deformed deformation member may break the first protective layer and the second protective layer.

[0015] The deformation of the deformation member may mean that a deformation portion is formed in the deformation member due to an increase in the internal temperature of the secondary battery.

[0016] The fact that the deformation member breaks the first protective layer and the second protective layer means that the deformation portion is formed at a broken portion in the first protective layer and the second protective layer.

[0017] The first protective layer includes a first shell and a first material layer, the first material layer includes a first material, and the second protective layer includes a second shell and a second material layer, the second material layer includes a second material, wherein the first material and the second material are different materials from each other.

[0018] The first material may include a hardening catalyst, and the second material may include an adhesive.

[0019] As the first protective layer and the second protective layer are broken, the first material and the second material may contact and react with each other.

[0020] A hardened layer may be formed inside the battery case through the reaction between the first material and the second material.

[0021] The first shell and the second shell may include one or more materials selected from the group consisting of low-density polyethylene LDPE, high-density polyethylene HDPE, oriented polypropylene (OPP), cast polypropylene CPP, oriented nylon ON, cast nylon CN, and polyethylene terephthalate PET.

[0022] The first material may include one or more materials selected from the group consisting of polyol, polyether polyol, and polyester polyol.

[0023] The second material may include one or more materials selected from the group consisting of diisocyanate TDI, methylene diphenyl diisocyanate MDI, hexamethylene diisocyanate (HDI), and isophorone diisocyanate IPDI.

[0024] A content ratio of the first material to the second material may be 30:70 to 70:30.

[0025] The deformable member may include a shape memory alloy layer or an electroactive polymer layer.

[0026] The secondary battery may further include a piezoelectric element connected to the electroactive polymer layer.

[0027] According to another embodiment of the present disclosure, there is provided a device including the above-mentioned secondary battery.

[0028] Beneficial Effects

[0029] According to an embodiment, even if the temperature of the secondary battery 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 hardening catalyst and the adhesive contact and react with each other to form a hardened layer inside the shell, thereby minimizing the probability of thermal runaway and keeping the secondary battery in a safe state.

[0030] The effects of the present disclosure are not limited to the above-mentioned effects, and additional other effects that are not mentioned will be clearly understood by those skilled in the art from the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a cross-sectional view showing a secondary battery according to an embodiment of the present disclosure;

[0032] Figure 2 yes Figure 1 , and is a cross-sectional view showing a protection member included in a secondary battery according to an embodiment of the present disclosure;

[0033] Figure 3 It is shown Figure 2 A cross-sectional view showing a state in which a protective member is deformed due to a temperature increase of a secondary battery;

[0034] Figure 4 yes Figure 3 an enlarged view of part B;

[0035] Figure 5 The embodiment of the present disclosure is viewed from above. Figures 1 to 4 A plan view of a partial configuration of a secondary battery described in;

[0036] Figure 6 yes Figure 1 , and is a cross-sectional view showing a protection member included in a secondary battery according to another embodiment of the present disclosure;

[0037] Figure 7 It is shown Figure 6 A cross-sectional view of a state in which a protective member is deformed due to a temperature increase of a secondary battery; and

[0038] Figure 8 The embodiment of the present invention is viewed from above Figure 6 and Figure 7 A plan view of a partial configuration of a secondary battery described in FIG. DETAILED DESCRIPTION

[0039] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice them. The present disclosure can be modified in various different ways without being limited to the embodiments set forth herein.

[0040] To clearly describe the present disclosure, parts irrelevant to the description will be omitted, and the same reference numerals designate the same elements throughout the description.

[0041] In addition, since the size and thickness of each element shown in the drawings are arbitrarily illustrated for the sake of convenience of explanation, it will be apparent that the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thickness is exaggerated to clearly show several layers and regions. In the drawings, the thickness of some layers and regions is exaggerated for the sake of convenience of explanation.

[0042] In addition, throughout the description, when a part is referred to as “including” or “comprising” a certain component, it means that the part may further include other components without excluding the other components, unless otherwise specified.

[0043] In addition, throughout the description, when referred to as “plane”, it means that the target portion is viewed from the upper side, and when referred to as “cross section”, it means that the target portion is viewed from the side of the cross section cut vertically.

[0044] Now, a secondary battery according to the present disclosure will be described with reference to the accompanying drawings.

[0045] Figure 1 is a cross-sectional view showing a secondary battery according to an embodiment of the present disclosure.

[0046] Reference Figure 1 According to the present embodiment, the secondary battery 100 includes: an electrode assembly 10 including a positive electrode 11, a negative electrode 12 and a separator 13; a battery case 50 accommodating the electrode assembly 10; and a protective member 40 formed between the electrode assembly 10 and the battery case 50, wherein 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.

[0047] The electrode assembly 10 includes a positive electrode 11, a negative electrode 12, and a separator 13 interposed between the positive electrode 11 and the negative electrode 12. In addition, a positive electrode tab 21 is formed on one side of the positive electrode 11, 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 at regular intervals. The tabs may be connected to a positive electrode lead 31 and a negative electrode lead 32, respectively, thereby being connected to an external circuit.

[0048] In addition, 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 generally be made of a laminated sheet including a resin layer and a metal layer. At this time, in order to be electrically connected to the outside of the electrode assembly 10, portions of the positive electrode lead 31 and the negative electrode lead 32 may be sealed by a bag while being exposed to the outside. However, the type of the battery case 50 is not limited thereto, and may be a prismatic case or a cylindrical case.

[0049] In this embodiment, the secondary battery 100 includes a protective member 40 formed between the electrode assembly 10 and the battery case 50. Figure 1 As shown in , the protection member 40 is formed between the electrode assembly 10 and the battery case 50 and may be formed on both the upper and lower portions of the electrode assembly 10 , but is not limited thereto and may be positioned corresponding to only one surface of the electrode assembly 10 .

[0050] Figure 2 yes Figure 1 2 is an enlarged view of a portion A of , and is a cross-sectional view showing a protection member included in a secondary battery according to an embodiment of the present disclosure. Figure 3 It is shown Figure 2A cross-sectional view of a state in which a protective member is deformed due to a temperature increase of a secondary battery. Figure 4 yes Figure 3 An enlarged view of part B. Figure 5 is a plan view of a partial configuration of a secondary battery according to an embodiment of the present disclosure, viewed from above.

[0051] Reference Figure 2 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. Figure 1 and Figure 2 The first protective layer 41 is illustrated as being located on the battery case 50 side and the second protective layer 45 is located on the electrode assembly 10 side, but the present disclosure is not limited thereto, and 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 the cell operation is not disturbed, the first protective layer 41 and the second protective layer 45 may be provided on a lead portion such as the positive electrode lead 31 or the negative electrode lead 32, or in a portion of the sealed pouch-type battery case 50.

[0052] In addition, refer 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. Figure 5 , illustration of the first protective layer 41 is omitted, but it will be apparent that the first protective layer 41 is formed in an upper portion of the shape memory alloy layer 43 .

[0053] At this time, refer to Figure 2 and Figure 4 , the first protective layer 41 may include a first shell 41a and a first material layer 41b including a first material, and the second protective layer 45 may include a second shell 45a and a second material layer 45b including a second material. The first material and the second material may be different materials from each other.

[0054] Therefore, in Figure 2 and Figure 4 In the embodiment, 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 shell 41a and the second shell 45a 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.

[0055] On the other hand, in the case of the secondary battery 100 , self-heating may occur in a high potential and high temperature storage environment, and therefore, when the internal temperature of the secondary battery 100 increases due to such self-heating of the secondary battery 100 , the shape memory alloy layer 43 may deform.

[0056] Reference Figure 3 and Figure 4 When the internal temperature of the secondary battery 100 increases, the shape memory alloy layer 43 is deformed at a temperature before thermal runaway occurs, and the deformed shape memory alloy layer 43 may rupture the first protective layer 41 and the second protective layer 45. In one example, since thermal runaway occurs at approximately 140 to 150 degrees Celsius, the shape memory alloy layer 43 may operate at a temperature of about 130 degrees Celsius or less.

[0057] 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 .

[0058] Specifically, the shape memory alloy is a material that restores a shape before deformation when heated to a certain temperature or higher, and when the internal temperature of the secondary battery 100 increases using this phenomenon, a deformation portion 43 ′ may be formed in the shape memory alloy layer 43 .

[0059] Therefore, the shape memory alloy layer 43 ruptures the first and second protective layers 41 and 45, which may mean that the deformation portion 43' ruptures the first and second protective layers 41 and 45. More specifically, the deformation portion 43' forms rupture portions 41a' and 45a' in the first and second protective layers 41 and 45, thereby rupturing the first and second protective layers 41 and 45.

[0060] Specifically, the ruptures 41a' and 45a' may be formed on the first shell 41a and the second shell 45a. That is, the ruptures 41a' and 45a' are respectively formed on the first shell 41a and the second shell 45a so that the first material layer 41b and the second material layer 45b may be respectively exposed to the outside of the first shell 41a and the second shell 45a.

[0061] Therefore, during the self-heating of the secondary battery 100 according to the present embodiment, since the first protection layer 41 and the second protection layer 45 are broken, the first material layer 41 b and the second material layer 45 b may contact and react with each other.

[0062] At this time, the first material layer 41 b may include a hardening catalyst, and the second material layer 45 b may include an adhesive.

[0063] Therefore, through the reaction between the first material layer 41a and the second material layer 45b, a hardened layer can be formed inside the battery housing 50. The inner wall of the battery housing 50 is reinforced by such a hardened layer, thereby not only delaying the temperature rise due to self-heating, but also delaying and suppressing the occurrence of thermal runaway by utilizing the delay in temperature rise.

[0064] In order to break due to the deformation of the shape memory alloy layer 43 in this way, the first shell 41a and the second shell 45a may include one or more materials selected from the group consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), oriented polypropylene (OPP), cast polypropylene (CPP), oriented nylon (ON), cast nylon (CN) and polyethylene terephthalate (PET). The above materials are materials that can be broken due to a predetermined pressure generated when the deformation portion 43' is formed in the shape memory alloy layer 43. In addition, the thickness of the first shell 41a and the second shell 45a can be 10μm to 50μm. If the thickness is less than 10μm, the first shell 41a and the second shell 45a can be destroyed even under a small impact, so that a hardened layer can be formed, so this is not preferred. If the thickness exceeds 50μm, the first shell 41a and the second shell 45a are not destroyed despite the deformation of the shape memory alloy layer 43, so that a hardened layer cannot be formed, so this is not preferred.

[0065] In addition, the first material layer 41 b may include one or more materials selected from the group consisting of polyol, polyether polyol, and polyester polyol.

[0066] The second material layer 45 b may include one or more materials selected from the group consisting of triisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0067] Therefore, a compound such as polyurethane may be formed by the reaction between the first material layer 41 b and the second material layer 45 b , thereby forming a hardened layer.

[0068] In order to effectively cause a reaction between the first material layer 41 b and the second material layer 45 b when in contact, a content ratio of the first material layer 41 b and the second material layer 45 b may be 30:70 to 70:30.

[0069] The first material and the second material may be semi-solid materials with a viscosity ranging from 10 to 90,000 cP. If the viscosity is too low, the first material or the second material may flow out to cause a reaction even when the first shell 41a and the second shell 45a are not destroyed, so this is not preferred. If the viscosity is too high, even if the first shell 41a and the second shell 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, which is not preferred.

[0070] In the 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 shells 41a and 45a, so that normal operation is possible without forming a hardened layer. In addition, if the internal temperature of the secondary battery 100 rises due to various reasons under abnormal conditions such as overcharge, high potential or high temperature storage environment, the shape memory alloy layer 43 is deformed, and the first material layer 41b and the second material layer 45b contact each other to form a hardened layer. Thus, by reinforcing the inner wall of the battery housing 50, thermal runaway caused by additional temperature rise can be delayed and the safety of the secondary battery can be further improved.

[0071] Figure 6 yes Figure 1 : is an enlarged view of a portion A of , and is a cross-sectional view showing a protection member included in a secondary battery according to another embodiment of the present disclosure. Figure 7 It is shown Figure 6 A cross-sectional view of a state in which a protective member is deformed due to a temperature increase of a secondary battery. Figure 8 The embodiment of the present invention is viewed from above Figure 6 and Figure 7 A plan view of a partial configuration of a secondary battery described in FIG.

[0072] Reference Figure 6 According to the present embodiment, the protective member 46 may include a first protective layer 41, a second protective layer 45, and a degeneration member formed between the first protective layer 41 and the second protective layer 45. Figures 2 to 5 The shape memory alloy layer 43 described in the embodiment may include a piezoelectric element 47 and an electroactive polymer layer 48 as a deformable member.

[0073] According to the present embodiment, at least one electroactive polymer layer 48 may be electrically and / or physically connected to the piezoelectric element 47. Figure 8 , the piezoelectric element 47 may be in contact with the electroactive polymer layer 48 at portions of both side surfaces, and may be connected to the piezoelectric element 47 using a connecting member 49. With this connection structure, an electrical signal generated by applying pressure to the piezoelectric element 47 may be transmitted to the electroactive polymer layer 48 via the connecting member 49.

[0074] Specifically, due to the internal temperature increase and / or gas generation of the secondary battery 100, pressure increases, and the pressure may be transmitted to the piezoelectric element 47. When pressure is applied to the piezoelectric element 47, the electroactive polymer layer 48 operates under the action of the current generated thereby. Figure 7As shown in FIG. 4 , the electroactive polymer layer 48 may be physically deformed to form a deformed portion 48 ′ in the electroactive polymer layer 48 . The first protective layer 41 and the second protective layer 45 may be broken due to the deformed portion 48 ′. Figure 7 The shape of the deformation portion 48' shown in FIG. 4 is an example, and Figure 7 The shape of the deformed portion 48 ′ shown in FIG. 4 may be deformed due to contraction and expansion of the electroactive polymer layer 48 due to ion movement and diffusion in response to a change in external voltage.

[0075] In addition to the above description regarding the electroactive polymer layer 48, Figures 2 to 5 The contents described in the embodiment of the present invention also apply to this embodiment.

[0076] As described above, the secondary battery according to the present embodiment can be applied to various devices. Specifically, it can be applied to vehicle devices such as electric bicycles, electric vehicles, or hybrid vehicles, but is not limited thereto and can be applied to various devices that can use secondary batteries.

[0077] The present invention has been described in detail with reference to the preferred embodiments of the present invention. However, it will be appreciated by those skilled in the art that the scope of the present disclosure is not limited thereto, and that various modifications and improvements may be made in these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined in the appended claims and their equivalents.

[0078] [Explanation of Reference Numerals]

[0079] 10: Electrode assembly

[0080] 21, 22: Positive terminal, negative terminal

[0081] 31, 32: Positive lead, negative lead

[0082] 40: Protective components

[0083] 41: First protective layer

[0084] 43: Shape memory alloy layer

[0085] 45: Second protection layer

[0086] 47: Piezoelectric element

[0087] 48: Electroactive polymer layer

[0088] 50: Battery housing

[0089] 100: Secondary battery

Claims

1. A secondary battery, comprising: An electrode assembly, the electrode assembly comprising a positive electrode, a negative electrode and a separator; a battery housing, the battery housing housing the electrode assembly; as well as a protective member formed between the electrode assembly and the battery case, Wherein, the protection component comprises: The first protective layer, A second protective layer, and A property-changing member is formed between the first protective layer and the second protective layer.

2. The secondary battery according to claim 1, wherein When the internal temperature of the secondary battery increases, the denaturing member is deformed, and The deformed deformable member breaks the first protective layer and the second protective layer.

3. The secondary battery according to claim 2, wherein: The deformation of the denaturing member means that a deformation portion is formed in the denaturing member due to an increase in the internal temperature of the secondary battery.

4. The secondary battery according to claim 3, wherein The fact that the deformation member breaks the first protective layer and the second protective layer means that the deformation portion forms a breaking portion in the first protective layer and the second protective layer.

5. The secondary battery according to claim 4, wherein The first protective layer includes a first shell and a first material layer, the first material layer includes a first material, and the second protective layer includes a second shell and a second material layer, the second material layer includes a second material, The first material and the second material are different materials.

6. The secondary battery according to claim 5, wherein The first material includes a hardening catalyst, and The second material includes an adhesive.

7. The secondary battery according to claim 5, wherein As the first protective layer and the second protective layer are broken, the first material and the second material come into contact with each other and react.

8. The secondary battery according to claim 5, wherein A hardened layer is formed inside the battery case through the reaction between the first material and the second material.

9. The secondary battery according to claim 5, wherein The first shell and the second shell include one or more materials selected from the group consisting of low-density polyethylene LDPE, high-density polyethylene HDPE, oriented polypropylene OPP, cast polypropylene CPP, oriented nylon ON, cast nylon CN, and polyethylene terephthalate PET.

10. The secondary battery according to claim 5, wherein The first material includes one or more materials selected from the group consisting of polyol, polyether polyol, and polyester polyol.

11. The secondary battery according to claim 5, wherein The second material includes one or more materials selected from the group consisting of diisocyanate TDI, methylene diphenyl diisocyanate MDI, hexamethylene diisocyanate HDI, and isophorone diisocyanate IPDI.

12. The secondary battery according to claim 5, wherein The content ratio of the first material to the second material is 30:70 to 70:

30.

13. The secondary battery according to claim 1, wherein The deformable member includes a shape memory alloy layer or an electroactive polymer layer. 14 . The secondary battery according to claim 3 , further comprising a piezoelectric element connected to the electroactive polymer layer.

15. A device comprising the secondary battery according to claim 1.

Images