Electrode assembly, secondary battery, battery pack and vehicle

Abstract

The present invention provides an electrode assembly in which a first electrode, a separator, and a second electrode are laminated and wound, wherein the outermost portion of the electrode assembly comprises a void space in which the first electrode covers the end of the second electrode through the separator and a thickness buffer provided in the void space, and a secondary battery comprising the same. The present invention provides a battery pack including the secondary battery and an automobile including the same.

Description

Technology Field

[0001] The present invention relates to an electrode assembly, a secondary battery, a battery pack, and an automobile. The present application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0078696 filed with the Korean Intellectual Property Office on June 28, 2022, the contents of which are incorporated herein by reference. Background Technology

[0002] Secondary batteries, which possess electrical characteristics such as high energy density and high applicability across product categories, are widely applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) driven by electric power sources.

[0003] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they not only have the primary advantage of being able to drastically reduce the use of fossil fuels but also the advantage of not generating any by-products from the use of energy.

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. The operating voltage of these individual secondary battery cells is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, multiple secondary batteries are connected in series to form a battery pack. Additionally, depending on the charge / discharge capacity required for the battery pack, multiple secondary batteries are connected in parallel to form a battery pack. Accordingly, the number of secondary batteries included in the battery pack and the electrical connection type can be set in various ways depending on the required output voltage and / or charge / discharge capacity. The problem to be solved

[0005] The present invention aims to provide an electrode assembly and a secondary battery capable of realizing high energy density by providing a thickness buffer in the empty space of the outermost part of the electrode assembly.

[0006] Another objective of the present invention is to provide a battery pack including a secondary battery having the improved structure as described above, and a vehicle including the same.

[0007] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below. means of solving the problem

[0008] One embodiment of the present invention provides an electrode assembly in which a first electrode, a separator, and a second electrode are laminated and wound, wherein the outermost portion of the electrode assembly comprises a void space in which the first electrode covers the end of the second electrode through the separator, and a thickness buffer provided in the void space.

[0009] Another embodiment of the present invention provides a secondary battery comprising an electrode assembly according to the above embodiment.

[0010] Another embodiment of the present invention provides a battery pack comprising a secondary battery according to the above embodiment.

[0011] Another embodiment of the present invention provides a vehicle comprising a battery pack according to the above-described embodiment. Effects of the invention

[0012] According to the development trend of secondary batteries requiring high capacity and high power, when coating an electrode active material layer on a current collector, the thickness of the current collector becomes thinner and the thickness of the electrode active material layer coated on the current collector becomes thicker in order to increase the energy density of the electrode.

[0013] In a conventional electrode assembly, when the positive electrode has a free edge where the end of the current collector and the end of the electrode active material layer coincide, a void is created by covering the end of the positive electrode coated with a thick electrode active material layer at the outermost part of the electrode assembly with the negative electrode.

[0014] The empty space formed on one side of the cathode facing the above-mentioned positive pre-edge end causes stress concentration when the electrode assembly is repeatedly charged and discharged, resulting in a problem where cracks frequently occur.

[0015] According to embodiments of the present invention, by providing a thickness buffer in the empty space formed in the cathode at the outermost part of the electrode assembly, the occurrence of cracks that may be formed by said empty space can be prevented.

[0016] This allows for the resolution of safety issues that may arise from cracks formed on the negative electrode and enables a stable increase in the current applied to the battery. Accordingly, it is possible to achieve high energy density and provide a high-capacity, high-output secondary battery.

[0017] However, the advantageous effects obtainable through the present invention are not limited to those described above, and other unmentioned effects will be clearly understood by those skilled in the art from the description of the invention below. Brief explanation of the drawing

[0018] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a schematic diagram showing the form in which a first electrode and a second electrode face each other at the outermost part of a conventional electrode assembly according to a comparative example of the present invention. Figure 2 is a photograph showing a case where a crack occurs due to a void space formed on one side of the first electrode at the outermost part of a conventional electrode assembly according to a comparative example of the present invention. FIG. 3 (a) is a drawing illustrating an electrode assembly according to FIG. 1, and (b) is a drawing illustrating an electrode assembly according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing the form in which the first electrode and the second electrode face each other at the outermost part of the electrode assembly according to an embodiment of the present invention. FIG. 5 shows an electrode assembly according to an embodiment of the present invention, (a) is a front view and (b) is a top view. FIGS. 6 to 8 are schematic plan views showing the first electrode and the second electrode of an electrode assembly according to an embodiment of the present invention. FIG. 9 is a diagram showing the schematic configuration of a battery pack including secondary batteries according to an embodiment of the present invention. FIG. 10 is a diagram showing the schematic configuration of a vehicle including a battery pack according to an embodiment of the present invention. Specific details for implementing the invention

[0019] Terms and words used in this specification and claims are not limited to their ordinary or dictionary meanings, and must be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0020] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0021] In addition, the term "…part" in the specification refers to a unit that processes at least one function or operation.

[0022] The embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0023] To aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Additionally, the same reference numerals may be assigned to identical components in different embodiments.

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0025] One embodiment of the present invention provides an electrode assembly (111) in which a first electrode (100), a separator, and a second electrode (200) are stacked and wound, wherein the outermost portion (211) of the electrode assembly comprises a void space (400) in which the first electrode (100) covers the end (250) of the second electrode through the separator, and a thickness buffer portion (500) provided in the void space (400).

[0026] The first electrode (100) may be a negative electrode, and the second electrode (200) may be a positive electrode.

[0027] By providing a thickness buffer (500) in the empty space (400) formed in the outermost part (211) of the electrode assembly, the occurrence of cracks caused by the empty space (400) can be prevented, and safety problems that may occur as a result can be resolved.

[0028] FIG. 1 is a schematic diagram showing the form in which the first electrode (10) and the second electrode (20) face each other at the outermost part (2) of a conventional electrode assembly according to a comparative example of the present invention, and FIG. 2 is a photograph showing a case in which a crack occurs due to an empty space formed on one side of the first electrode at the outermost part of a conventional electrode assembly according to a comparative example of the present invention.

[0029] Referring to FIG. 1 and 2, in the case where the end of the second electrode (20) in the existing electrode assembly (1) has a free edge where the end of the current collector and the end of the electrode active material layer coincide, the end of the second electrode (20) coated with a thick electrode active material layer at the outermost part (2) of the electrode assembly can be covered with the first electrode (10) to create an empty space (40).

[0030] The above empty space (40) can be formed on one side of the first electrode (10) facing it by interposing a separator at the end of the second electrode (20).

[0031] The above empty space (40) has a problem in that stress is concentrated when the electrode assembly is repeatedly charged and discharged, causing cracks (C) to occur frequently. For example, the above empty space (40) may be formed in an active material layer or a non-active area provided in a current collector on one side of the first electrode (10) facing the end of the second electrode (20), and when the electrode assembly is repeatedly charged and discharged, stress is concentrated in the active material layer or non-active area, so cracks may easily occur.

[0032] According to one embodiment, the second electrode (200) having a free edge means that the end of the current collector (210) and the end of the electrode active material layer (220, 230) coincide at the second electrode. For example, a non-free portion may not be formed at the end (250) of the second electrode.

[0033] Accordingly, the second electrode (200) may have a middle tab structure, and the middle tab structure means further including a second electrode tab (240) provided in a portion other than both ends in the direction (P) perpendicular to the winding axis of the electrode assembly. Therefore, both ends in the direction (P) perpendicular to the winding axis of the electrode assembly may have a free edge in which a blank portion is not formed. (See FIGS. 6 to 8 to be described later)

[0034] In the above-mentioned conventional electrode assembly, if the end of the second electrode (20) has a free edge where the end of the current collector and the end of the electrode active material layer coincide, stress may be concentrated due to the empty space (40), causing a crack (C), and as a result, safety problems such as a short circuit or ignition may occur in the electrode.

[0035] FIG. 3 (a) is a front view showing the first electrode (10) and the second electrode (20) at the outermost part (2) of an electrode assembly according to one comparative example of the present invention, and FIG. 3 (b) is a front view showing the first electrode (100) and the second electrode (200) at the outermost part (211) of an electrode assembly according to one embodiment of the present invention.

[0036] Referring to FIGS. 3 (a) and (b), the electrode assembly (1, 111) includes a first electrode (10, 100), a separator (not shown), and a second electrode (20, 200). For example, the electrode assembly (1, 111) may be formed by stacking and winding the first electrode (10, 100), the separator (not shown), and the second electrode (20, 200). FIG. 3 only shows the first electrode (10, 100) and the second electrode (20, 200) with the separator omitted, but it is also possible to wind two or more unit cells consisting of the first electrode (10, 100) and the second electrode (20, 200).

[0037] Referring to FIG. 3 (a), when the end of the second electrode (25) of the existing electrode assembly (1) has a free edge where the end of the current collector and the end of the electrode active material layer coincide, the end of the second electrode (25) coated with a thick electrode active material layer at the outermost part (2) of the electrode assembly can be covered by the first electrode (10) to create a void space (40). In the void space (40) formed on one side of the first electrode facing the second electrode end (25), stress is concentrated when the electrode assembly (1) is repeatedly charged and discharged, and a crack (C) may occur.

[0038] The empty space (40) formed on one side of the first electrode may be formed on one side of the first electrode active material layer (13) or the first electrode non-active portion (15) provided in the first electrode current collector (11), and when the electrode assembly (1) is repeatedly charged and discharged, stress may be concentrated on the first electrode active material layer (13) or the first electrode non-active portion (15), causing a crack (C) to easily occur.

[0039] FIG. 4 is a schematic diagram showing the form in which the first electrode (100) and the second electrode (200) face each other at the outermost part (211) of the electrode assembly according to an embodiment of the present invention.

[0040] FIG. 5 shows an electrode assembly (111) according to an embodiment of the present invention, (a) is a front view and (b) is a top view.

[0041] Referring to FIGS. 3 (b) to FIGS. 5, the electrode assembly (111) may have a jelly roll structure in which a first electrode (100), a separator (not shown), and a second electrode (200) are stacked and wound, and the electrode assembly (111) may be wound in a circular or elliptical shape.

[0042] The outermost part (211) of the electrode assembly may be provided at the end of the winding of the wound electrode assembly and may be the part furthest from the winding axis direction.

[0043] An empty space (400) covering the end (250) of the second electrode can be formed on one side of the first electrode (100) of the outermost part (211) of the electrode assembly with the separator interposed therebetween, and this may include a thickness buffer (500).

[0044] By providing a thickness buffer (500) in the empty space (400) formed on one side of the first electrode (100) at the outermost part (211) of the electrode assembly, the occurrence of cracks caused by the empty space (400) can be prevented.

[0045] According to one embodiment, the first electrode (100) comprises a first electrode current collector (110) and a first electrode active material layer (130) provided on the first electrode current collector (110), and the thickness buffer (500) is provided directly on a surface facing the center of the winding of the first electrode or via the separator between the end (250) of the second electrode and the end of the first electrode active material layer (130).

[0046] The thickness buffer portion (500) is not limited to the length from the end (250) of the second electrode to the end of the first electrode active material layer (130). For example, the thickness buffer portion (500) may be provided directly on the surface facing the center of the winding of the first electrode between the first electrode unwound portion (150) beyond the end of the first electrode active material layer (130) or by interposing the separator.

[0047] For example, the thickness buffer (500) may be provided with a length of 50% or more relative to the length between the end (250) of the second electrode and the end of the first electrode active material layer (130). The thickness buffer (500) may be 50% or more, 55% or more, 60% or more, 65% or more, or 70% or more relative to the length between the end (250) of the second electrode and the end of the first electrode active material layer (130). The thickness buffer (500) may be 100% or less, 95% or less, or 90% or less relative to the length between the end (250) of the second electrode and the end of the first electrode active material layer (130).

[0048] When the above range is satisfied, a thickness buffer (500) is provided in the empty space (400) formed in the outermost part (211) of the electrode assembly, thereby preventing the occurrence of cracks caused by the empty space (400).

[0049] According to one embodiment, the thickness buffer is provided with a thickness less than or equal to the thickness of the end portion of the second electrode. For example, the thickness (T2) of the thickness buffer may be provided with a thickness of 70% to 100% relative to 100% of the thickness (T1) of the end portion of the second electrode.

[0050] By providing a thickness buffer according to the thickness range, the occurrence of cracks caused by the empty space (400) in the electrode assembly (111) can be prevented.

[0051] According to one embodiment, the thickness buffer (500) does not overlap with the end (250) of the second electrode, and the thickness buffer (500) may be provided spaced apart from the end (250) of the second electrode by a distance (I) of 3 mm or less.

[0052] If the thickness buffer is provided in contact with the end of the second electrode and the range (I) without being spaced apart from the end of the second electrode, the empty space (400) formed in the outermost part of the electrode assembly may become larger, and thus, when charging and discharging are repeated on the electrode assembly (111), stress may be concentrated in the empty space (400) and a crack may occur.

[0053] The thickness buffer is provided with a length of 50% to 100% relative to 100% of the electrode assembly length in the winding axis direction of the electrode assembly.

[0054] The length (HL) of the thickness buffer section may be 50% or more, 55% or more, 60% or more, 65% or more, or 70% or more relative to 100% of the length of the electrode assembly in the winding axis direction (H) of the electrode assembly. The length (HL) of the thickness buffer section may be 100% or less, 95% or less, 90% or less, 85% or less, or 80% or less relative to 100% of the length of the electrode assembly in the winding axis direction (H) of the electrode assembly.

[0055] When the above range is satisfied, the occurrence of cracks that may be formed in the empty space (400) can be prevented due to the thickness buffer (500) provided in the empty space (400) formed in the outermost part (211) of the electrode assembly.

[0056] According to one embodiment, the second electrode (200) comprises a second electrode current collector (210) and a second electrode active material layer (220, 230) provided on the second electrode current collector (210), and at the end (250) of the second electrode, the end of the second electrode current collector (210) and the end of the second electrode active material layer (220, 230) coincide.

[0057] The fact that the end of the second electrode current collector (210) and the end of the second electrode active material layer (220, 230) coincide at the end (250) of the second electrode may mean that the end (250) of the second electrode in the electrode assembly (111) has a free edge, and that no uneven portion is formed at both ends in the direction (P) perpendicular to the winding axis of the electrode assembly of the second electrode (200).

[0058] The fact that the end of the second electrode current collector (210) and the end of the second electrode active material layer (220, 230) coincide means that the lengths of the second electrode current collector (210) and the second electrode active material layer (220, 230) are the same at the end (250) of the second electrode, and at this time, the length of the second electrode current collector (210) and the length of the second electrode active material layer (220, 230) may be within the general error range of the industry. For example, the length of the second electrode current collector (210) relative to the length of the second electrode active material layer (220, 230) at the end (250) of the second electrode may be +0.5% or less.

[0059] According to one embodiment, the end (250) of the second electrode is provided at the end of the winding of the wound electrode assembly.

[0060] The first electrode (100) may include a first electrode active material layer (120, 130) on at least one surface of the first electrode current collector (110), and the second electrode (200) may include a second electrode active material layer (220, 230) on at least one surface of the second electrode current collector (210).

[0061] These first electrode (100) and second electrode (200) are not particularly limited and can be manufactured in a form in which the first electrode active material or the second electrode active material is attached to the first electrode current collector (110) and the second electrode current collector (210), respectively, according to conventional methods known in the art.

[0062] The first electrode (100) may have a first electrode active material layer (130) on one surface of the first electrode current collector (110) at the outermost part (211) of the electrode assembly, and may include a non-active part (15) where the active material layer is not provided.

[0063] On the other hand, the end (250) of the second electrode may be present at the outermost part (211) of the electrode assembly.

[0064] The end portion (250) of the second electrode is provided with a second electrode active material layer (220, 230) on each side of the second electrode current collector (210), and may have a free edge structure that does not include a non-circular portion. That is, the end portion (250) of the second electrode may include the end portion of the second electrode active material layer (220, 230) and the end portion of the second electrode current collector (210), which have the same length in the direction (P) perpendicular to the winding axis, and the end portion of the second electrode active material layer (220, 230).

[0065] According to one example, the first electrode active material layer (130) of the first electrode (100) may face the second electrode active material layer (230) of the second electrode (200) through a separator.

[0066] According to one embodiment, the first electrode (100) is provided longer in a direction (P) perpendicular to the winding axis than the second electrode (200) facing it via the separator, and the first electrode active material layer (130) provided on the surface facing the winding center of the first electrode (100) is provided longer in a direction (P) perpendicular to the winding axis than the end (250) of the second electrode facing it via the separator.

[0067] By providing the first electrode active material layer (130) as being longer than the end (250) of the second electrode, i.e., the second electrode active material layer (230), damage to the separator can be prevented even when charging the electrode assembly (111), and a reduction in the battery life can be prevented.

[0068] The first electrode (100) is extended longer than the second electrode (200). That is, the end (250) of the second electrode is formed to be shorter than the end of the first electrode (100) facing it.

[0069] Accordingly, at the outermost part (211) of the electrode assembly, the first electrode (100) can cover the end (250) of the second electrode through the separator. The end (250) of the second electrode may be provided at the end of the winding of the wound electrode assembly and located at the outermost part (211) of the electrode assembly.

[0070] In the case where the end (25) of the second electrode in the existing electrode assembly (1) has a free-edge structure in which the end (25) of the second electrode current collector (21) and the end of the electrode active material layer (22, 23) overlap, the first electrode (10) can cover the end (25) of the second electrode through the separator, and an empty space (40) can be formed.

[0071] The above empty space (40) may be formed on one or both sides of the first electrode (10) facing the second electrode (20) by the thickness (T1) of the end of the second electrode, and when charging and discharging, stress may be concentrated in the empty space (40), which may cause damage to the separator interposed between them or cause a short circuit between the two electrodes due to the occurrence of a crack (C) in the electrode (see FIGS. 1 to 3 (a)).

[0072] However, the outermost portion (211) of the electrode assembly according to one embodiment of the present invention is provided with a thickness buffer portion (500) in the empty space (400) in which the first electrode (100) covers the end portion (250) of the second electrode through the separator. The thickness buffer portion (500) can relieve stress concentration in the empty space (400), thereby maintaining the separator between the first electrode (100) and the second electrode (200) and preventing cracks (C) in the electrodes, thereby ensuring the stability of the battery.

[0073] According to one embodiment, the thickness buffer (500) may be provided between the end of the first electrode active material layer (130) and the point facing the end (250) of the second electrode. By providing the thickness buffer (500) at the above location, the occurrence of cracks caused by the empty space (400) can be prevented, and safety problems that may arise as a result can be resolved.

[0074] According to one embodiment of the present invention, the thickness buffer (500) is an electrolyte swelling layer.

[0075] The above electrolyte swelling layer may be impregnated with a liquid to expand or become flexible, and may be made of a polymer material.

[0076] As one of the characteristics of the above polymer material, solvent molecules can penetrate between the chains of the polymer material, thereby increasing its volume.

[0077] Therefore, since the electrolyte swelling layer expands or becomes flexible when it absorbs the electrolyte, it can relieve stress concentration in the empty space (400), thereby preventing the occurrence of cracks caused by the empty space (400) and resolving safety issues that may arise as a result.

[0078] According to one embodiment, the electrolyte swelling layer comprises polyurethane. However, the electrolyte swelling layer is not limited thereto as long as it is swollen by the electrolyte.

[0079] The above electrolyte swelling layer can be swollen by the electrolyte containing the above compound, thereby relieving stress concentration in the above empty space (400) and preventing damage to the separator and electrode.

[0080] The above electrolyte swelling layer can be considered to be swollen when the thickness (T2) of the thickness buffer portion is 90% to 100% of the end thickness (T1) of the second electrode, and the thickness (T2) of the thickness buffer portion can be measured by a thickness measuring instrument.

[0081] According to one embodiment of the present invention, the thickness buffer (500) is an electrolyte swelling tape comprising the electrolyte swelling layer.

[0082] According to one embodiment, the width (HL) of the swelling tape may be 50% to 100% relative to the width of the first electrode. The width (HL) of the swelling tape may be 50% or more, 55% or more, 60% or more, 65% or more, or 70% or more relative to the width of the first electrode. The width (HL) of the swelling tape may be 100% or less, 95% or less, 90% or less, 85% or less, or 80% or less relative to the width of the first electrode.

[0083] When the width (HL) of the swelling tape satisfies the above range, the occurrence of cracks that may be formed due to the empty space (400) can be prevented, and safety problems that may occur as a result can be resolved.

[0084] According to one embodiment, the first electrode (100) comprises a first electrode current collector (110) and a first electrode active material layer (130) provided on the first electrode current collector (110), and the electrolyte swelling tape is attached directly to the surface facing the center of the winding of the first electrode between the end (250) of the second electrode and the end of the first electrode active material layer (130), or via the separator.

[0085] For example, the electrolyte swelling tape may be provided with a length of 50% or more relative to the length between the end (250) of the second electrode and the end of the first electrode active material layer (130). The electrolyte swelling tape may be 50% or more, 55% or more, 60% or more, 65% or more, or 70% or more relative to the length between the end (250) of the second electrode and the end of the first electrode active material layer (130). The electrolyte swelling tape may be 100% or less relative to the length between the end (250) of the second electrode and the end of the first electrode active material layer (130).

[0086] When the above range is satisfied, the occurrence of cracks caused by the above empty space (400) can be prevented, and safety problems that may occur as a result can be resolved.

[0087] Additionally, the electrolyte swelling tape is not limited to a length from the end (250) of the second electrode to the end of the first electrode active material layer (130). For example, the electrolyte swelling tape may be provided directly on the surface facing the center of the winding of the first electrode between the first electrode unwound portion (150) and beyond the end of the first electrode active material layer (130), or with the separator interposed therebetween.

[0088] According to one embodiment of the present invention, the first electrode (100) includes a blank portion (150) in which the electrode active material layer is not provided at the edge portion of the first electrode current collector (110) provided at one end in a direction (P) perpendicular to the winding axis at the outermost portion (211) of the electrode assembly, and further includes a protective tape (160) provided on the blank portion (150).

[0089] According to one embodiment, the first electrode (100) further includes a tab (140) provided at one or more of both ends in the longitudinal direction of the electrode assembly, that is, in the direction (P) perpendicular to the winding axis of the electrode assembly, and the second electrode (200) further includes a tab (240) provided at a portion other than both ends in the direction (P) perpendicular to the winding axis of the electrode assembly.

[0090] FIG. 5 shows an electrode assembly (111) according to an embodiment of the present invention, (a) is a front view and (b) is a top view.

[0091] FIGS. 6 to 8 are schematic plan views showing the first electrode and the second electrode of an electrode assembly according to an embodiment of the present invention.

[0092] Referring to FIGS. 5 to 8, a first electrode tab (140) is formed that is electrically connected to the first electrode current collector (110) of the first electrode (100) and protrudes to the outside of the electrode assembly (111), and the first electrode tab (140) provides a passage through which current is input or output during the charging or discharging process of the secondary battery.

[0093] In this case, the protective tape (160) may be positioned on the unprotected portion (150) of the first electrode current collector electrically connected to the first electrode tab (140) and on the portion opposite in the thickness direction of the unprotected portion, such as a mark. In this way, the protective tape (160) can cover and protect not only the first electrode tab (140) but also the mark that may be formed on the opposite side thereof when the first electrode tab (140) is formed. Additionally, for the convenience of the battery manufacturing process, the end of the first electrode protective tape (160) may coincide with the end of the first electrode.

[0094] By providing the protective tape (160) on the first electrode (100), a short circuit with the end (250) of the second electrode can be prevented. Additionally, the protective tape (160) can also prevent a short circuit between the outermost first electrode (100) and the outermost second electrode (200) caused by a mark created when the first electrode tab (140) is formed. Therefore, a short circuit of the electrode can be prevented by the protective tape (160) provided on the first electrode (100) facing the second electrode (200).

[0095] The length of the protective tape (160) in the winding axis direction (H) may be about 100 to about 120%, preferably about 105 to about 110%, of the length of the first electrode current collector (110) in the winding axis direction (H). When the length of the protective tape (160) in the winding axis direction (H) satisfies the above range, a short circuit between the electrodes can be prevented and an electrochemical reaction of the desired first electrode active material can be induced.

[0096] The protective tape (160) may comprise one or more selected from the group consisting of polypropylene, polyethyleneterephthalate, and polyimide. Additionally, the protective tape (160) can protect the first electrode active material layer by adhering with excellent elasticity and durability in response to volume changes during charging and discharging.

[0097] One embodiment of the present invention provides a secondary battery (600) comprising at least one of the aforementioned electrode assemblies (111).

[0098] According to one embodiment, the secondary battery (600) may include an electrode assembly (111), a battery can, a seal, and terminals.

[0099] In the electrode assembly (111) above, the first electrode (100) may be a negative electrode, and the second electrode (200) may be a positive electrode having polarity opposite to that of the first electrode (100). The first electrode (100) and the second electrode (200) may have a sheet shape. The electrode assembly (111) may have, for example, a jelly roll shape. That is, the electrode assembly (111) may be manufactured by winding a laminate formed by sequentially stacking the first electrode (100), the separator, the second electrode (200), and the separator at least once, with respect to the winding center. In this case, an additional separator may be provided on the outer surface of the electrode assembly (111) to insulate it from the battery can.

[0100] In the present invention, the positive active material coated on the positive current collector and the negative active material coated on the negative current collector may be used without limitation as long as they are active materials known in the art.

[0101] Non-limiting examples of the above-mentioned positive active material include conventional positive active materials that can be used in the positives of conventional electrochemical devices, and in particular, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or lithium composite oxides that are combinations thereof may be used.

[0102] In one example, the positive active material is the general chemical formula A[A x M y ]O 2+z It may include an alkali metal compound represented by (A contains at least one element among Li, Na and K; M contains at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x ≥ 0, 1 ≤ x+y ≤ 2, -0.1 ≤ z ≤ 2; the stoichiometric coefficients of the components included in x, y, z and M are selected so that the compound maintains electrical neutrality).

[0103] In another example, the positive active material is an alkali metal compound xLiM disclosed in US6,677,082, US6,680,143, etc. 1 O 2-(1-x) Li2M 2 O3(M 1 It comprises at least one element having an average oxidation state of 3; M 2 It contains at least one element having an average oxidation state of 4; 0≤x≤1).

[0104] In another example, the positive active material is, with the general chemical formula Li a M 1 x Fe 1-x M 2 P y1-y M 3 z O 4-z (M 1Silver comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M3 comprises a halogen element optionally including F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; a, x, y, z, M 1 , M 2 , and M 3 The stoichiometric coefficient of the component included in the compound is selected so that the compound maintains electrical neutrality), or may be a lithium metal phosphate represented as Li3M2(PO4)3 [M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al].

[0105] Preferably, the positive active material may include primary particles and / or secondary particles formed by the aggregation of primary particles.

[0106] Non-limiting examples of cathode active materials include conventional cathode active materials that can be used in the cathodes of conventional electrochemical devices, and in particular, lithium adsorbent materials such as lithium metal or lithium alloy, carbon, petroleum coke, activated carbon, graphite, or other carbons may be used.

[0107] In one example, the negative electrode active material may be a carbon material, lithium metal or lithium metal compound, silicon or silicon compound, tin or tin compound, etc. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V may also be used as negative electrode active materials. As for the carbon material, low-crystallinity carbon, high-crystallinity carbon, etc. may all be used.

[0108] Non-limiting examples of positive current collectors include foils made of aluminum, nickel, or combinations thereof, and non-limiting examples of negative current collectors include foils made of copper, gold, nickel, or copper alloys or combinations thereof.

[0109] The separator may be a porous polymer film, such as a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, or ethylene / methacrylate copolymer, used alone or in a laminate thereof. As another example, the separator may be a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers.

[0110] At least one surface of the separation membrane may include a coating layer of inorganic particles.

[0111] In addition, it is possible for the membrane itself to consist of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure bonded to a binder such that interstitial volume exists between adjacent particles. The inorganic particles may be composed of inorganic materials having a dielectric constant of 5 or higher. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3 - It may include at least one material selected from the group consisting of PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0112] The electrolyte is A + B -It may be a salt having a structure like that. Here, A + is Li + , Na + , K + It includes alkali metal cations such as or ions composed of combinations thereof. And B - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It includes one or more anions selected from the group consisting of

[0113] The electrolyte can also be used by dissolving it in an organic solvent. As organic solvents, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone, or mixtures thereof may be used.

[0114] Another embodiment of the present invention provides a battery pack (700) comprising at least one of the aforementioned secondary batteries (600). For example, the secondary battery (600) may be a cylindrical secondary battery.

[0115] The cylindrical secondary battery (600) according to the above-described embodiment can be used to manufacture a battery pack (700).

[0116] FIG. 9 is a diagram showing the schematic configuration of a battery pack (700) including secondary batteries (600) according to an embodiment of the present invention.

[0117] Referring to FIG. 9, a battery pack (700) according to an embodiment of the present invention includes an assembly in which cylindrical secondary batteries (600) are electrically connected and a pack housing (710) that accommodates the same. The cylindrical secondary batteries (600) are battery cells according to the embodiment described above. In the drawings, for convenience of drawing, components such as busbars, cooling units, and external terminals for electrically connecting the cylindrical secondary batteries are omitted.

[0118] Another embodiment of the present invention provides a vehicle (800) comprising at least one of the aforementioned battery packs (700).

[0119] The above battery pack (700) may be mounted on a vehicle (800). The vehicle (800) may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle.

[0120] FIG. 10 is a drawing for explaining a vehicle (800) including the battery pack (700) of FIG. 9.

[0121] Referring to FIG. 10, a vehicle (800) according to one embodiment of the present invention includes a battery pack (700) according to one embodiment of the present invention. The vehicle operates by receiving power from the battery pack (700) according to one embodiment of the present invention.

[0122] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0123] 1, 111: Electrode assembly 2, 211: Outermost part of the electrode assembly 10, 100: First electrode 11, 110: First electrode current collector 12, 13, 120, 130: First electrode active material layer 14, 140: First electrode tab 15, 150: First electrode non-existent portion 16, 160: Protective tape 20, 200: Second electrode 21, 210: Second electrode current collector 22, 23, 220, 230: Second electrode active material layer 24, 240: Second electrode tab 25, 250: Second electrode end 40, 400: empty space 500: Thickness buffer 600: Secondary battery 700: Battery pack 710: Pack Housing 800: Car C: Crack H: Winding axis direction HL: Length of the thickness buffer in the winding axis direction P: Direction perpendicular to the winding axis PL: Length of the thickness buffer in the direction perpendicular to the winding axis T1: Thickness of the second electrode end T2: Thickness of the thickness buffer I: Spacing between the second electrode end and the thickness buffer.

Claims

Claim 1 An electrode assembly in which a first electrode, a separator, and a second electrode are laminated and wound, wherein the first electrode is a negative electrode and the second electrode is a positive electrode, and the outermost portion of the electrode assembly comprises a void space in which the first electrode covers the end of the second electrode through the separator and a thickness buffer provided in the void space. Claim 2 An electrode assembly according to claim 1, wherein the first electrode comprises a first electrode current collector and a first electrode active material layer provided on the first electrode current collector, and the thickness buffer is provided either directly on a surface facing the winding center of the first electrode or via the separator between the end of the second electrode and the end of the first electrode active material layer. Claim 3 An electrode assembly according to claim 2, wherein the thickness buffer is provided with a length of at least 50% relative to the length between the end of the second electrode and the end of the first electrode active material layer. Claim 4 An electrode assembly according to claim 1, wherein the thickness buffer is provided with a thickness less than or equal to the thickness of the end of the second electrode. Claim 5 An electrode assembly according to claim 4, wherein the thickness buffer is provided with a thickness of 70% to 100% relative to the thickness of the end portion of the second electrode. Claim 6 An electrode assembly according to claim 1, wherein the thickness buffer does not overlap with the end of the second electrode. Claim 7 An electrode assembly according to claim 1, wherein the thickness buffer is provided with a length of 50% to 100% relative to 100% of the electrode assembly length in the winding axis direction of the electrode assembly. Claim 8 An electrode assembly according to claim 1, wherein the second electrode comprises a second electrode current collector and a second electrode active material layer provided on the second electrode current collector, and the end of the second electrode current collector and the end of the second electrode active material layer coincide at the end of the second electrode. Claim 9 An electrode assembly according to claim 1, wherein the end of the second electrode is provided at the winding end of the wound electrode assembly. Claim 10 An electrode assembly according to claim 1, wherein the first electrode is provided longer in a direction perpendicular to the winding axis than the second electrode facing it via the separator. Claim 11 An electrode assembly according to claim 2, wherein the first electrode active material layer provided on the surface facing the center of the winding of the first electrode is provided longer in a direction perpendicular to the winding axis than the end of the second electrode facing it, with the separator interposed therebetween. Claim 12 An electrode assembly according to claim 1, wherein the thickness buffer is an electrolyte swelling layer. Claim 13 An electrode assembly according to claim 12, wherein the electrolyte swelling layer comprises polyurethane. Claim 14 An electrode assembly according to claim 12, wherein the thickness buffer is an electrolyte swelling tape comprising the electrolyte swelling layer. Claim 15 An electrode assembly according to claim 14, wherein the first electrode comprises a first electrode current collector and a first electrode active material layer provided on the first electrode current collector, and the electrolyte swelling tape is attached directly to a surface facing the center of the winding of the first electrode or via the separator between the end of the second electrode and the end of the first electrode active material layer. Claim 16 An electrode assembly according to claim 2, wherein the first electrode comprises a non-existent portion in which the first electrode active material layer is not provided at the edge portion of the first electrode current collector provided at one end in a direction perpendicular to the winding axis at the outermost portion of the electrode assembly, and further comprises a protective tape provided at the non-existent portion. Claim 17 An electrode assembly according to claim 1, wherein the first electrode further comprises a tab provided at one or more of both ends in a direction perpendicular to the winding axis of the electrode assembly. Claim 18 An electrode assembly according to claim 1, wherein the second electrode further comprises a tab provided at a portion other than both ends in a direction perpendicular to the winding axis of the electrode assembly. Claim 19 delete Claim 20 A secondary battery comprising an electrode assembly according to any one of claims 1 to 18. Claim 21 A battery pack comprising a secondary battery according to claim 20. Claim 22 An automobile comprising at least one battery pack according to claim 21.

Images