Secondary battery and device including the same

Abstract

A secondary battery according to one embodiment of the present disclosure includes: an electrode assembly with a jelly-roll structure, the electrode assembly including a positive electrode sheet, a negative electrode sheet and a separator; a cylindrical shell in which the electrode assembly is built; and a flat coil spring located between an outer peripheral surface of the electrode assembly and an inner wall of the cylindrical shell.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2019-0165769 filed in the Korean Intellectual Property Office on December 12, 2019, the disclosure of which is incorporated herein by reference in its entirety.

[0003] The present disclosure relates to a secondary battery and a device including the secondary battery, and more particularly, to a secondary battery including an electrode assembly having a jelly-roll structure and a device including the secondary battery. Background Art

[0004] Recently, with the rise in energy prices due to the depletion of fossil fuels and the growing concern about environmental pollution, the demand for environmentally friendly alternative energy is bound to play an important role in future life. Therefore, research on technologies for generating various power such as nuclear power, solar power, wind power and tidal power is underway, and power storage devices for more efficient use of the generated energy are also attracting attention.

[0005] In particular, as the technology of mobile devices develops and the demand for mobile devices increases, the demand for batteries as energy sources is rapidly increasing. Accordingly, many studies have been conducted on batteries that can meet various demands.

[0006] Typically, a lithium secondary battery, such as a lithium ion battery or a lithium ion polymer battery, having advantages such as high energy density, discharge voltage, output stability, etc., is highly desired.

[0007] In addition, secondary batteries can be classified based on the shape of the battery case into: a cylindrical battery having an electrode assembly installed in a cylindrical metal can; a prismatic battery having an electrode assembly installed in a prismatic metal can; and a pouch-shaped battery having an electrode assembly installed in a pouch-shaped case made of a laminated aluminum sheet.

[0008] In addition, secondary batteries may also be classified based on how to configure an electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are stacked.

[0009] Typically, the electrode assembly may include: a jelly roll (winding) type electrode assembly, in which a long sheet type positive electrode and a long sheet type negative electrode are wound with a separator interposed therebetween; and a stacked (laminated) type electrode assembly, in which a plurality of positive electrodes and negative electrodes cut into predetermined unit sizes are sequentially stacked with a separator interposed therebetween; etc.

[0010] Recently, in order to solve the problems involved in the jelly roll type electrode assembly and the stacked type electrode assembly, a stacked / folded type electrode, which is a combination of the jelly roll type electrode assembly and the stacked type electrode assembly, has been developed. The stacked / folded type electrode assembly has a structure in which the stacked unit cells of the positive electrode and the negative electrode of a specific unit are sequentially wound while being located on a separator with a separator interposed therebetween.

[0011] Meanwhile, in the case of lithium secondary batteries, a "bulge phenomenon" may occur: while the electrode thickens during repeated charging and discharging processes, the volume of the electrode assembly expands. If this bulge phenomenon deepens, not only the performance of the secondary battery deteriorates, but also the shape of the secondary battery may change, thus adversely affecting the structural stability.

[0012] Particularly, in the case of a lithium secondary battery using pure lithium metal as a negative electrode, the charging mechanism is different from that of a general graphite negative electrode, and thus, the thickness expansion of the negative electrode causes a bulging phenomenon of the secondary battery, which may cause serious problems.

[0013] In the graphite negative electrode, intercalation of lithium transferred from the positive electrode into graphite as a layered structure occurs, but in the lithium metal negative electrode, the negative electrode deposited on the positive electrode is stacked as it is, making the thickness variation of the secondary battery more serious.

[0014] For example, when 4.0 mAh / cm 2 When the positive electrode is loaded with 20 μm, the 20 μm lithium metal negative electrode can be extended by 10 μm on both sides, and when the Cu current collector is used, the 50 μm lithium metal negative electrode increases to 90 μm. In particular, considering that the lithium metal negative electrode is porous and lithium dendrite growth occurs, the thickness variation of the secondary battery may be more serious.

[0015] Therefore, there is a need to develop a secondary battery capable of effectively controlling volume expansion occurring during charge and discharge. Summary of the invention

[0016] Technical issues

[0017] Embodiments of the present disclosure have been designed to solve the above-mentioned problems of the aforementioned methods, and an object of the present disclosure is to provide a secondary battery capable of effectively controlling volume expansion occurring during charging and discharging, and a device including the secondary battery.

[0018] However, the problems to be solved by the embodiments of the present disclosure are not limited to the above-mentioned problems, and can be variously extended within the scope of the technical ideas included in the present disclosure.

[0019] Technical Solution

[0020] A secondary battery according to an embodiment of the present disclosure includes: an electrode assembly with a jelly-roll structure, the electrode assembly including a positive electrode sheet, a negative electrode sheet and a separator; a cylindrical shell in which the electrode assembly is built; and a flat coil spring located between an outer peripheral surface of the electrode assembly and an inner wall of the cylindrical shell.

[0021] The flat coil spring may be configured such that one end makes contact with the electrode assembly and the other end makes contact with the inner wall of the cylindrical case, and the flat coil spring wraps the electrode assembly one or more turns.

[0022] A positive electrode tab attached to the positive electrode tab may extend upward from the electrode assembly, and a negative electrode tab attached to the negative electrode tab may extend downward from the electrode assembly.

[0023] One end of the flat coil spring may overlap at least one of the positive electrode tab or the negative electrode tab in a radial direction of the electrode assembly.

[0024] The thickness of the flat coil spring increases from one end toward the other end.

[0025] The flat coil spring may include a first flat coil spring and a second flat coil spring, the first flat coil spring and the second flat coil spring respectively located at both ends of the electrode assembly with respect to a height direction of the electrode assembly.

[0026] The flat coil spring may further include a third flat coil spring located between the first flat coil spring and the second flat coil spring.

[0027] Compared to the third flat coil spring, the first flat coil spring and the second flat coil spring may have a larger spring constant, or the number of turns wrapping the electrode assembly may be increased.

[0028] A positive electrode tab attached to the positive electrode tab may extend upward from the electrode assembly, and a negative electrode tab attached to the negative electrode tab may extend downward from the electrode assembly.

[0029] In an outer circumferential surface of the electrode assembly, the first flat coil spring and the second flat coil spring may wrap portions corresponding to portions to which the positive electrode tab and the negative electrode tab are attached, respectively.

[0030] The negative electrode active material may be coated on the negative electrode sheet, and the negative electrode active material may include at least one of Li, Si, SiO 2 , or Sn.

[0031] Beneficial effects

[0032] According to an embodiment of the present disclosure, a flat coil spring is arranged between an electrode assembly having a jelly-roll structure and a cylindrical shell, so that not only the position of the electrode assembly is stably fixed but also the volume expansion of the electrode assembly generated during charging and discharging is suppressed, thereby enabling reversible charging and discharging. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is an exploded perspective view of an electrode assembly according to one embodiment of the present disclosure.

[0034] Figure 2 It is shown Figure 1 A perspective view of a state in which an electrode assembly is wound and then wrapped in a flat coil spring.

[0035] Figure 3 Yes Figure 2 A cross-sectional perspective view of a secondary battery including an electrode assembly and a flat coil spring.

[0036] Figure 4 It is a graphic Figure 3 Schematic horizontal cross-sectional view along line AA' in FIG.

[0037] Figure 5 is a perspective view showing a state in which the electrode assembly is wrapped in the first to third flat coil springs. DETAILED DESCRIPTION

[0038] 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 implement them. The present disclosure can be modified in various different ways and is not limited to the embodiments set forth herein.

[0039] Parts irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification.

[0040] In addition, in the drawings, for the convenience of description, the size and thickness of each element are arbitrarily illustrated, and the present disclosure is not necessarily limited to what is shown in the drawings. In the drawings, for the sake of clarity, the thickness of layers, regions, etc. is exaggerated. In the drawings, for the convenience of description, the thickness of some layers and regions is exaggeratedly shown.

[0041] In addition, it will be understood that when an element such as a layer, film, region, or plate is referred to as being "on" or "above" another element, the element can be directly on the other element, or there may also be intervening elements. In contrast, when an element is referred to as being "directly on" another element, this means that there are no other intervening elements. Furthermore, the terms "on" or "above" mean being placed on or below a reference portion, and do not necessarily necessarily mean being placed on the upper end of the reference portion facing in the direction opposite to gravity.

[0042] Furthermore, throughout the specification, when a part is referred to as “comprising” a specific component, it means that the part can further include other components, without excluding the other components, unless otherwise stated.

[0043] Furthermore, throughout the specification, when referred to as a “plane”, this means that the target portion is viewed from the upper side, and when referred to as a “section”, this means that the target portion is viewed from the section side cut vertically.

[0044] Figure 1 is an exploded perspective view of an electrode assembly 100 according to one embodiment of the present disclosure, Figure 2 It is shown Figure 1 A perspective view of a state in which the electrode assembly 100 is wound and then wrapped in a flat coil spring 500, and Figure 3 Yes Figure 2 A cross-sectional perspective view of a secondary battery including an electrode assembly and a flat coil spring.

[0045] refer to Figures 1 to 3 According to one embodiment of the present disclosure, a secondary battery 10 includes: an electrode assembly 100 having a jelly-roll structure, the electrode assembly 100 including a positive electrode sheet 200, a negative electrode sheet 300 and a separator 400; a cylindrical shell 600, in which the electrode assembly 100 is built; and a flat coil spring 500, which is located between an outer circumferential surface 101 of the electrode assembly 100 and an inner wall of the cylindrical shell 600.

[0046] The electrode assembly 100 having a jelly roll structure is formed such that the positive electrode sheet 200, the negative electrode sheet 300, and the separator 400 are wound together, and the separator 400 may be interposed between the positive electrode sheet 200 and the negative electrode sheet 300. In addition, when wound in the form of a jelly roll, in order to prevent the positive electrode sheet 200 and the negative electrode sheet 300 from contacting each other, the separator 400 may be additionally disposed below the negative electrode sheet 300.

[0047] The positive electrode active material is coated on the positive electrode sheet 200 to form the positive electrode active material layer 220 , and the positive electrode tab 210 may be bonded to the positive electrode non-coating portion 230 where the positive electrode active material layer 220 is not formed by a method such as welding.

[0048] Similarly, a negative electrode active material is coated on the negative electrode sheet 300 to form a negative electrode active material layer 320 , and the negative electrode tab 310 may be bonded to the negative electrode uncoated portion 330 where the negative electrode active material layer 320 is not formed by a method such as welding.

[0049] At this time, Figure 1 , the positive electrode uncoated portion 230 and the negative electrode uncoated portion 330 are respectively formed at one end of the positive electrode sheet 200 and the negative electrode sheet 300, but they correspond to one example and can be formed in the middle by being separated from one end of the positive electrode sheet 200 and the negative electrode sheet 300.

[0050] At the same time, as in Figure 1 As shown in , it is desirable that the extension directions of the positive electrode tab 210 and the negative electrode tab 310 are opposite to each other. Figure 2 As shown in , when the electrode assembly 100 is wound, the positive electrode tab 210 may extend upward (in the z-axis direction) from the electrode assembly 100, and the negative electrode tab 310 may extend downward (in the direction opposite to the z-axis direction) from the electrode assembly 100.

[0051] Figure 4 It is a graphic Figure 3 Schematic horizontal cross-sectional view along line AA' in FIG.

[0052] and Figures 1 to 3 Reference together Figure 4 The flat coil spring 500 located between the outer circumferential surface 101 of the electrode assembly 100 and the inner wall of the cylindrical shell 600 may be configured such that one end 501 makes contact with the electrode assembly 100 and the other end 502 makes contact with the inner wall of the cylindrical shell 600 .

[0053] In addition, such a flat coil spring 500 may wrap the electrode assembly 100 one or more times, thereby effectively pressing the electrode assembly 100 .

[0054] As described above, a "bulging phenomenon" may occur: during repeated charge and discharge processes, the volume of the electrode assembly 100 expands. If this bulging phenomenon deepens, not only the performance of the secondary battery is deteriorated, but also the shape of the secondary battery may change, thereby adversely affecting structural stability.

[0055] Therefore, according to this embodiment, the flat coil spring 500 located between the outer circumferential surface 101 of the electrode assembly 100 and the inner wall of the cylindrical shell 600 can not only stably fix the electrode assembly 100 inside the cylindrical shell 600, but also effectively suppress the volume expansion of the electrode assembly 100.

[0056] When the volume expansion of the electrode assembly 100 is not suppressed, the distance between the positive electrode sheet 200 and the negative electrode sheet 300 increases and the resistance increases due to the volume expansion, and eventually, reversible discharge may not be performed. At this time, the flat coil spring 500 according to the present embodiment can effectively suppress the volume expansion of the electrode assembly 100, thereby enabling the secondary battery to be reversibly charged and discharged.

[0057] In addition, since the spring has a spiral shape, uniform pressure can be applied to the entire outer circumferential surface 101 of the electrode assembly 100. That is, the effect of suppressing volume expansion can be uniformly exhibited over the entire outer circumferential surface 101.

[0058] In addition, Figure 4 , it is exaggeratedly shown for explanation, but the flat coil spring 500 is a spring wound in a spiral shape, and thus can be disposed between the inside of the cylindrical case 600 and the cylindrical jelly-roll electrode assembly 100 without occupying a large volume. That is, space utilization is improved, which has the advantage of increasing battery capacity.

[0059] In particular, since the electrode assembly 100 has a relatively small volume when the electrode assembly 100 is in a discharged state, the flat coil spring 500 may be disposed on the outer circumferential surface of the electrode assembly 100 in the discharged state and then embedded in the cylindrical case 600 .

[0060] Thereafter, when charging is performed and the electrode assembly 100 expands, the flat coil spring 500 may apply uniform pressure to the entire outer circumferential surface of the electrode assembly 100 as described above.

[0061] Meanwhile, one end 501 of the flat coil spring 500 can overlap at least one of the positive electrode tab 210 or the negative electrode tab 310 in the radial direction of the electrode assembly 100 .

[0062] Here, the radial direction means a direction corresponding to a radius based on the center of the electrode assembly 100 when the wound electrode assembly 100 is viewed from above.

[0063] exist Figure 4 , only the state in which one end 501 overlaps with the positive electrode tab 210 in the radial direction is shown, but the negative electrode tab 310 may also overlap with the one end 501 in the radial direction.

[0064] The wound electrode assembly 100 can only have an asymmetrical shape when viewed from above due to the positive electrode tab 210 and the negative electrode tab 310 respectively attached to the positive electrode sheet 200 and the negative electrode sheet 300. When the electrode assembly 100 expands due to charging and discharging, the asymmetrical shape is further deepened, which may cause a problem of shape distortion.

[0065] Therefore, one end 501 of the flat coil spring 500 is arranged to overlap at least one of the positive electrode tab 210 or the negative electrode tab 310 in the radial direction of the electrode assembly 100, so that the highest pressure can be applied to the portion where the shape distortion is most likely to occur. Thus, the shape distortion of the electrode assembly 100 caused by the positive electrode tab 210 or the negative electrode tab 310 during volume expansion can be minimized.

[0066] Furthermore, although not specifically shown, the thickness of the flat coil spring 500 may increase as the flat coil spring 500 moves from the other end 502 toward the one end 501 .

[0067] By forming a thickness gradient in the flat coil spring 500 in this way, one end 501 of the flat coil spring 500 arranged at a position corresponding to the positive electrode tab 210 or the negative electrode tab 310 can be designed to apply a stronger elastic force. Thus, the shape distortion of the electrode assembly 100 caused by the positive electrode tab 210 or the negative electrode tab 310 during volume expansion can be minimized.

[0068] At the same time, refer again Figure 2 , the flat coil spring 500 according to the present embodiment may wrap the entire outer circumferential surface 101 of the electrode assembly 100. This is to apply uniform pressure to the entire outer circumferential surface 101 of the electrode assembly 100.

[0069] Figure 5 is a perspective view showing a state in which the electrode assembly 100 is wrapped in the first to third flat coil springs 510 , 520 , and 530 as a modified embodiment of the present disclosure.

[0070] refer to Figure 5 As described above, the positive electrode tab 210 may extend upward (in the z-axis direction) from the electrode assembly 100, and the negative electrode tab 310 may extend downward (in the direction opposite to the z-axis direction) from the electrode assembly 100.

[0071] The flat coil spring 500a according to the present embodiment may include a first flat coil spring 510 and a second flat coil spring 520, which are respectively located at both ends of the electrode assembly 100 in the height direction (direction parallel to the z-axis) of the electrode assembly 100. In particular, in the outer circumferential surface 101 of the electrode assembly 100, the first flat coil spring 510 and the second flat coil spring 520 may respectively wrap portions corresponding to portions to which the positive electrode tab 210 and the negative electrode tab 310 are attached.

[0072] In addition, the flat coil spring 500 a may include a third flat coil spring 530 located between the first flat coil spring 510 and the second flat coil spring 520 .

[0073] The flat coil springs are classified into first to third flat coil springs 510 , 520 , and 530 , but in order to apply uniform pressure to the entire outer circumferential surface 101 of the electrode assembly 100 , the first to third flat coil springs 510 , 520 , and 530 may wrap the entire outer circumferential surface 101 of the electrode assembly 100 .

[0074] In this case, the first flat coil spring 510 and the second flat coil spring 520 may have a larger spring constant, or the number of turns of wrapping the electrode assembly may be increased, compared to the third flat coil spring 530. That is, the pressure applied by the first flat coil spring 510 and the second flat coil spring 520 may be greater than the pressure applied by the third flat coil spring 530.

[0075] With respect to the height direction of the electrode assembly 100 (the direction parallel to the z-axis), both ends of the electrode assembly 100 correspond to the portions to which the positive electrode tab 210 and the negative electrode tab 310 are attached, respectively. As described above, due to the positive electrode tab 210 and the negative electrode tab 310, the wound electrode assembly 100 can only have an asymmetric shape when viewed from above, and when the electrode assembly 100 expands due to charging and discharging, this asymmetric shape may be further deepened, which may cause a problem of shape distortion.

[0076] Accordingly, the spring constant or the number of wrapped turns of the first flat coil spring 510 and the second flat coil spring 520 is made greater than the spring constant or the number of wrapped turns of the third flat coil spring 530, and a higher pressure is applied to the portion of the electrode assembly 100 where shape distortion may most frequently occur in the height direction.

[0077] Figure 5Only one positive electrode tab 210 and one negative electrode tab 310 are shown separately, but these are an example, and multiple positive electrode tabs 210 may extend upward and multiple negative electrode tabs 310 may extend downward. When both the positive electrode tab 210 and the negative electrode tab 310 are composed of multiple tabs in this way, shape distortion during volume expansion may be more problematic. Therefore, the first flat spiral spring 510 and the second flat spiral spring 520 according to the present embodiment may be more effective.

[0078] Referring again to Figure 1 , a negative electrode active material is coated on the negative electrode sheet 300 to form a negative electrode active material layer 320, wherein the negative electrode active material may include at least one of Li, Si, SiO2, or Sn.

[0079] When the negative electrode active material contains the above materials, a greater volume expansion is induced in the electrode assembly 100 including the negative electrode sheet 300. Accordingly, when the negative electrode active material includes at least one of Li, Si, SiO2, or Sn, the effect of suppressing volume expansion in the present disclosure by the flat spiral springs 500 and 500a may be more prominent.

[0080] More specific examples of the negative electrode active material may include: carbon, such as non-graphitizable carbon and graphitic carbon; metal composite oxides, such as Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2 (0 ≤ x ≤ 1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Groups 1, 2, and 3 in the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium titanium oxide, lithium metal; lithium alloy; silicon alloy; tin alloy; metal oxides, such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers, such as polyacetylene; Li-Co-Ni-based materials, etc.

[0081] Meanwhile, referring again to Figure 3 , the secondary battery 10 in the present disclosure can be manufactured by accommodating the electrode assembly 100 in a cylindrical case 600, injecting an electrolyte solution into the cylindrical case 600, and then coupling a cap assembly 700 to the upper end of the cylindrical case 600.

[0082] In this case, the cylindrical case 600 may include a crimping portion 610 and a curling portion 620.

[0083] The crimping portion 610 refers to a portion located above the crimping portion 620 to wrap around the cap assembly 700 , and is used for stable coupling of the cap assembly 700 .

[0084] The beading portion 620 refers to a portion of the cylindrical case 600 that is recessed in a central direction of the electrode assembly 100 , which is used for stable coupling of the cap assembly 700 and prevents the electrode assembly 100 from flowing.

[0085] The cap assembly 700 includes an upper cap 710 for forming a positive electrode terminal, a cap plate 730 to which the positive electrode tab 210 extending upward from the electrode assembly 100 is connected, and a gasket 720 for maintaining airtightness.

[0086] The gasket 720 is installed on the inner surface of the crimping portion 610 and the upper inner surface of the crimping portion 620 to increase the sealing force between the cap assembly 700 and the cylindrical housing 600 .

[0087] Meanwhile, the upper and lower insulating members 810 and 820 are respectively disposed on the upper and lower portions of the electrode assembly 100 , so that the electrode assembly 100 can be prevented from coming into contact with the cap assembly 700 or the bottom of the cylindrical case 600 and being energized.

[0088] Also, although not specifically shown, for electrical insulation, an insulating film wrapping the outer circumferential surface of the electrode assembly 100 may be added, and in the present disclosure, the insulating film may be located between the outer circumferential surface of the electrode assembly 100 and the flat coil spring 500 .

[0089] The center pin 900 may be embedded in the center of the electrode assembly 100. The center pin 900 generally includes a metal material to impart a predetermined strength, and is composed of a cylindrical structure in which a plate material is bent into a round shape. The center pin 900 may be used as a channel for fixing and supporting the electrode assembly 100 and for discharging gas generated by an internal reaction during charge / discharge and operation.

[0090] Meanwhile, the one or more secondary batteries according to the embodiments of the present disclosure can be applied to various devices. These devices can be applied to vehicles such as electric bicycles, electric vehicles, hybrid vehicles, but are not limited thereto, and can be applied to various devices that can use secondary batteries.

[0091] Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure defined in the appended claims also belong to the scope of rights.

[0092] Description of Reference Numerals

[0093] 10: Secondary battery

[0094] 100: Electrode assembly

[0095] 200: Positive electrode sheet

[0096] 210: Positive electrode terminal

[0097] 300: Negative electrode sheet

[0098] 310: Negative electrode terminal

[0099] 400: Separator

[0100] 500: Flat coil spring

[0101] 600: Cylindrical shell

Claims

1. A secondary battery comprising: An electrode assembly having a jelly roll structure, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet and a separator; A cylindrical shell, wherein the electrode assembly is built in the cylindrical shell; and a flat coil spring located between the outer peripheral surface of the electrode assembly and the inner wall of the cylindrical housing, The flat coil spring is configured such that one end of the flat coil spring contacts the electrode assembly and the other end of the flat coil spring contacts the inner wall of the cylindrical shell, and the flat coil spring wraps the electrode assembly one or more times. wherein a positive electrode tab attached to the positive electrode sheet extends upward from the electrode assembly, and A negative electrode tab attached to the negative electrode sheet extends downward from the electrode assembly, and The one end of the flat coil spring overlaps with at least one of the positive electrode tab or the negative electrode tab in a radial direction of the electrode assembly.

2. The secondary battery according to claim 1, in, The thickness of the flat coil spring increases from the other end toward the one end.

3. The secondary battery according to claim 1, in, The flat coil spring includes a first flat coil spring and a second flat coil spring, and the first flat coil spring and the second flat coil spring are respectively located at both ends of the electrode assembly in a height direction relative to the electrode assembly.

4. The secondary battery according to claim 3, in, The flat coil spring further includes a third flat coil spring located between the first flat coil spring and the second flat coil spring.

5. The secondary battery according to claim 4, in, Compared to the third flat coil spring, the first flat coil spring and the second flat coil spring have a larger spring constant or an increased number of turns wrapping around the electrode assembly.

6. The secondary battery according to claim 5, in, A positive electrode tab attached to the positive electrode sheet extends upward from the electrode assembly, and A negative electrode tab attached to the negative electrode sheet extends downward from the electrode assembly.

7. The secondary battery according to claim 6, in, In the outer peripheral surface of the electrode assembly, the first flat coil spring and the second flat coil spring respectively wrap portions corresponding to portions to which the positive electrode tab and the negative electrode tab are attached.

8. The secondary battery according to claim 1, in, A negative electrode active material is coated onto the negative electrode sheet, and The negative electrode active material includes at least one of Li, Si, SiO2 or Sn.

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

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