Electrode assembly and secondary battery comprising the same

Abstract

The present invention relates to an electrode assembly and a secondary battery including the same, wherein the leading edge of the positive plate is formed at an angle so as to disperse the stress applied to the deformation occurring at the center of the winding during charging and discharging of the secondary battery, thereby preventing the positive plate from penetrating the separator at the deformed area and short-circuiting with the negative plate. For example, the present invention relates to an electrode assembly formed by winding a laminate of a negative electrode plate, a separator, and a positive electrode plate, wherein the negative electrode plate has a negative coating layer formed on a negative electrode current collector plate, a positive electrode plate has a positive coating layer formed on a positive electrode current collector plate, and a separator interposed between the positive electrode plate and the negative electrode plate. The positive electrode plate comprises a one side extending along the longitudinal direction, a other side extending along the longitudinal direction opposite to the one side, a leading edge connecting the one side and the other side and located at the center of the winding of the wound electrode assembly and inclined to have an acute or obtuse angle with the one side, and a terminal edge connecting the one side and the other side and located at the outermost edge of the wound electrode assembly opposite to the leading edge. The invention also discloses a secondary battery comprising the same.

Description

Technology Field

[0001] Various embodiments of the present invention relate to an electrode assembly and a secondary battery including the same. Background Technology

[0002] Rechargeable batteries are power storage systems that provide excellent energy density by converting electrical energy into the form of chemical energy for storage. Unlike primary batteries, which are non-rechargeable, rechargeable batteries are widely used in IT devices such as smartphones, cellular phones, laptops, and tablet PCs. Recently, interest in electric vehicles has increased due to the need to prevent environmental pollution, leading to the adoption of high-capacity rechargeable batteries in these vehicles. These rechargeable batteries require characteristics such as high density, high output, and stability.

[0003] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. The problem to be solved

[0004] The present invention provides an electrode assembly capable of preventing short circuits caused by deformation by dispersing stress applied to deformation occurring during charging and discharging of a secondary battery through the inclined tip edge of the positive plate, and a secondary battery including the same. means of solving the problem

[0005] An electrode assembly according to an embodiment of the present invention and a secondary battery including the same comprises a negative electrode plate having a negative coating layer formed on a negative electrode current collector plate, a positive electrode plate having a positive coating layer formed on a positive electrode current collector plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and relates to an electrode assembly formed by winding a laminate of the negative electrode plate, the separator, and the positive electrode plate. The positive electrode plate may include a side extending along the longitudinal direction, a side extending along the longitudinal direction opposite to the side extending from

[0006] The above-mentioned tip side is located within the tip region, and within the tip region, the anode plate is in the shape of a right triangle, and the above-mentioned tip side may be the hypotenuse of the right triangle.

[0007] The above leading edge region may be wound by any one of 1 / 4 turn to 1 turn when winding the electrode assembly into a cylinder.

[0008] The above end side is parallel to the above end side, so the anode plate may be a parallelogram plate.

[0009] The above-mentioned cathode plate is a rectangular plate extending along the longitudinal direction and may include a side and a side parallel to one side of the anode plate, a leading side connecting one side of the cathode plate and the other side of the cathode plate and located at the center of the winding of the wound electrode assembly, and a trailing side connecting one side of the cathode plate and the other side of the cathode plate and located at the outermost edge of the wound electrode assembly opposite to the leading side of the cathode plate.

[0010] The leading edge of the above-mentioned cathode plate may be extended further along the longitudinal direction toward the center of the winding compared to the leading edge of the above-mentioned anode plate.

[0011] The leading edge of the above positive plate includes a first leading edge inclined at an acute angle from the first edge and a second leading edge inclined at an acute angle from the other edge and connected to the end of the first leading edge, and may have a bent portion at the part where the first leading edge and the second leading edge are connected.

[0012] The leading edge of the above positive plate includes a first leading edge inclined at an obtuse angle from the first edge and a second leading edge inclined at an obtuse angle from the other edge and connected to the end of the first leading edge, and may have a bent portion at the part where the first leading edge and the second leading edge are connected.

[0013] The above-mentioned bent portion may be located at the center of the above-mentioned tip edge.

[0014] The end edge of the above positive plate may have a shape corresponding to the leading edge.

[0015] In addition, an electrode assembly according to an embodiment of the present invention and a secondary battery including the same may include an electrode assembly, a case having an internal space and containing an electrolyte in the internal space of the electrode assembly, and a cap plate coupled to the upper part of the case to seal the case. Effects of the invention

[0016] An electrode assembly according to one embodiment of the present invention and a secondary battery including the same have a leading edge of the positive plate formed to be inclined, so that the stress applied to the deformation occurring at the center of the winding during charging and discharging of the secondary battery can be dispersed, thereby preventing the positive plate from penetrating the separator at the deformed area and thus preventing a short circuit with the negative plate. Brief explanation of the drawing

[0017] FIGS. 1a, FIGS. 1b, and FIGS. 1c are a perspective view, an exploded perspective view, and a longitudinal section view illustrating a secondary battery according to an embodiment of the present invention. FIGS. 2a and 2b are an exploded perspective view and a partially enlarged plan view illustrating an example of an electrode assembly of a secondary battery shown in FIGS. 1a to 1c before being wound. FIGS. 3A and FIGS. 3B are examples of deformation occurring at the center of the winding of the electrode assembly, and an enlarged perspective view showing the separator and the positive plate in FIG. 3A. FIGS. 4a and 4b are perspective views illustrating an example in which the leading edge region of the anode plate is wound 1 turn and an example in which the leading edge region of the anode plate is wound 1 / 4 turn. FIG. 5 is an exploded perspective view illustrating another example of the electrode assembly of the secondary battery shown in FIG. 1a to 1c before it is wound. Specific details for implementing the invention

[0018] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0019] The embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the invention is not limited to the following embodiments. Rather, these embodiments are provided to make the disclosure more faithful and complete and to fully convey the spirit of the invention to those skilled in the art.

[0020] Additionally, in the drawings below, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and like reference numerals in the drawings refer to like elements. As used herein, the term "and / or" includes any one of the listed items and all combinations of one or more thereof. Furthermore, in this specification, the meaning of "connected" refers not only to cases where Member A and Member B are directly connected, but also to cases where Member C is interposed between Member A and Member B so that Member A and Member B are indirectly connected.

[0021] The terms used herein are for describing specific embodiments and are not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Additionally, as used herein, "comprise" and / or "comprising" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups.

[0022] Although terms such as "first," "second," etc. are used in this specification to describe various components, parts, regions, layers, and / or parts, it is obvious that these components, parts, regions, layers, and / or parts should not be limited by these terms. These terms are used solely to distinguish one component, part, region, layer, or part from another region, layer, or part. Accordingly, the first component, part, region, layer, or part described below may refer to the second component, part, region, layer, or part without departing from the teachings of the present invention.

[0023] Spatial terms such as "beneath," "below," "lower," "above," and "upper" are used to facilitate understanding of one element or feature depicted in the drawings and another element or feature. These spatial terms are intended to facilitate understanding of the invention according to various process or usage states of the invention and are not intended to limit the invention. For example, if an element or feature in the drawings is inverted, an element described as "beneath" or "below" becomes "upper" or "on top." Therefore, "below" is a concept that encompasses "upper" or "below."

[0024] As illustrated in FIGS. 1a, 1b and 1c, a secondary battery (100) according to the present invention comprises a case (110), an electrode assembly (120) housed inside the case (110), and a cap assembly (130) that seals the top opening of the case (110).

[0025] The above case (110) includes a circular bottom portion (111) and a side portion (112) extending a certain length upward from the bottom portion (111). Here, the secondary battery (100) may be a cylindrical secondary battery formed by winding an electrode assembly (120) into a jelly roll shape. During the manufacturing process of the secondary battery (100), the top of the case (110) is open. Therefore, during the assembly process of the secondary battery, the electrode assembly (120) can be inserted into the case (110) together with the electrolyte. The above case (110) may be formed of steel, steel alloy, aluminum, aluminum alloy, or an equivalent thereof, but the material is not limited thereto. In addition, a beading part (113) that is inwardly recessed at the bottom of the case (110) with the cap assembly (130) as the center so that the electrode assembly (120) does not detach to the outside may be formed, and a crimping part (114) that is inwardly bent may be formed at the top thereof.

[0026] The electrode assembly (120) is housed inside the case (110) together with the electrolyte. Here, the electrolyte is an organic liquid containing a salt that is injected to allow lithium ions to move between the positive plate and the negative plate constituting the electrode assembly (120). It may comprise a non-aqueous organic electrolyte that is a mixture of a lithium salt such as LiPF6, LiBF4, LiClO4, etc., and a high-purity organic solvent, but the present invention is not limited thereto.

[0027] The electrode assembly (120) comprises a negative electrode plate (121) coated with a negative electrode active material, a positive electrode plate (122) coated with a positive electrode active material, and a separator (125) interposed between the negative electrode plate (121) and the positive electrode plate (122) to prevent a short circuit between the negative electrode plate (121) and the positive electrode plate (122) and to allow only the movement of lithium ions. The negative electrode plate (121), the positive electrode plate (122), and the separator (125) are wound in a roughly cylindrical shape. Additionally, a negative electrode tab (126) extending downward by a certain length may be attached to the negative electrode plate (121), and a positive electrode tab (127) extending upward by a certain length may be attached to the positive electrode plate (122), but the opposite is also possible.

[0028] Additionally, with reference to FIGS. 2a and 2b, an exploded perspective view and a partially enlarged plan view are shown, illustrating the electrode assembly of the secondary battery illustrated in FIGS. 1a to 1c prior to winding. FIG. 2b is an enlarged plan view of a certain area of ​​the winding tip in a plan view in which the negative electrode plate (121) and the positive electrode plate (122) are stacked prior to winding the electrode assembly (120). Of course, a separator (125) is interposed between the negative electrode plate (121) and the positive electrode plate (122), and the separator (125) is indicated by a dotted line to make the relationship between the positive electrode plate (122) and the negative electrode plate (121) clearer. Below, with reference to FIGS. 2a and 2b, the configuration of the secondary battery of the present invention and the electrode assembly will be described in detail.

[0029] First, the negative plate (121) of the electrode assembly (120) has a negative current collector plate (123a), which is a plate-shaped metal foil made of copper (Cu) or nickel (Ni), coated with a negative coating layer (123b), which is an active material made of a transition metal oxide, on both sides. The negative plate (121) may have a rectangular plate shape extending along the longitudinal direction (x). Here, the longitudinal direction (x) refers to the direction in which the negative plate (121), positive plate (122), and separator (125) are extended before the electrode assembly (120) is wound. The negative plate (121) may include a side (121a) extending along the longitudinal direction (x) and a side (121b) opposite to the side. Additionally, the negative plate (121) may further include a leading edge (121c) connecting one side (121a) and the other side (121b), and a trailing edge (121d). The leading edge (121c) and the trailing edge (121d) of the negative plate (121) may be perpendicular to the one side (121a) and the other side (121b). That is, the negative plate (121) may be a rectangular plate. Here, the leading edge (121c) may be located at the center of the winding of the wound electrode assembly (120), and the trailing edge (121d) may be located at the outermost edge of the wound electrode assembly (120).

[0030] Additionally, a cathode tab (126) may be attached to either the first surface of the cathode collector plate (123a) or the second surface opposite to the first surface. Furthermore, the cathode tab (126) may be extended by protruding a certain length from the longitudinal side (x) (121a) of the cathode collector plate (123a). The cathode tab (126) may be extended approximately perpendicularly from the longitudinal side (x) (121a) of the cathode collector plate (123a). Here, the cathode tab (126) may be attached to an uncoated area of ​​the cathode collector plate (123a) where the cathode coating layer (123b) is not coated. Preferably, the cathode tab (126) may be attached to an area adjacent to the end side (121d) of the cathode collector plate (123a). Of course, the negative electrode collector plate (123a) may be provided with an uncoated portion in the area adjacent to the end edge (121d) where the negative coating layer (123b) is not coated. However, the location where the negative tab (126) is attached in the present invention can be varied in many ways and is not limited thereto.

[0031] Additionally, an insulating tape (126a) may be further provided to cover the cathode tab (126) attached to the cathode collector plate (123a). The insulating tape (126a) may be attached to the cathode collector plate (123a) to cover the portion of the cathode tab (126) attached to the cathode collector plate (123a). At this time, the portion of the cathode tab (126) that protrudes a certain length from the lower part of the electrode assembly (120) may be exposed to the outside of the insulating tape (126a). Furthermore, the insulating tape (126a) may be attached to cover a portion of the cathode collector plate (123a) adjacent to the cathode tab (126) in the longitudinal direction (x). The cathode tab (126) may be made of copper or nickel, but the present invention is not limited thereto.

[0032] The anode plate (122) has an anode coating layer (124b), which is an active material made of a transition metal oxide, coated on both sides of an anode current collector plate (124a), which is a plate-shaped metal foil made of aluminum (Al). The anode plate (122) may have a rectangular plate shape extending along the longitudinal direction (x). The anode plate (122) may include a side (122a) extending along the longitudinal direction (x) and a side (122b) opposite to the side. Additionally, the anode plate (122) may further include a leading side (122c) connecting the side (122a) and the side (122b) and a trailing side (122d). One side (122a) and the other side (122b) of the positive plate (122) may be parallel to one side (121a) and the other side (121b) of the negative plate (121). Also, as shown in FIG. 2b, the leading side (122c) of the positive plate (122) may be shorter in the longitudinal direction (x) from the center of the winding of the electrode assembly (120) compared to the leading side (121c) of the negative plate (121). That is, the leading side (121c) of the negative plate (121) may be extended further toward the center of the winding compared to the leading side (122c) of the positive plate (122).

[0033] The leading edge (122c) of the positive plate (122) may be an inclined surface that is inclined to have an acute or obtuse angle with respect to the first side (122a). Although the leading edge (122c) is shown in FIG. 2a as being inclined at an acute angle from the first side (122a), it may be formed to be inclined at an obtuse angle. The leading edge (122c) of the positive plate (122) may be located within the leading edge region (a). The leading edge region (a) may be a certain area from the center of the winding of the electrode assembly (120). Here, the positive plate (122) in the leading edge region (a) may have a right-angled triangle shape, and the leading edge (122c) may be the hypotenuse. Here, since the leading edge (122c) located in the leading edge region (a) is formed as an inclined surface, it can disperse the stress generated during the charging and discharging of the secondary battery (100).

[0034] For example, FIGS. 3a and 3b show an example in which deformation occurs due to increased stress at the center of the winding of the electrode assembly (120) as the secondary battery (100) undergoes repeated charging and discharging, and an enlarged perspective view is shown of the separator (125) and positive plate (122) at the center of the winding of the electrode assembly (120) in which deformation has occurred. Here, the electrode assembly (120) may have a Z-deformation that is bent by compressive stress approximately parallel to the winding axis at the center of the winding. In such an electrode assembly (120), if the leading edge (122c) is perpendicular to the first edge (122a), stress is concentrated in the deformed part, and the positive plate (122) may penetrate the separator (125) and short circuit with the negative plate (121). That is, since the positive plate (122) of the secondary battery (100) has a leading edge (122c) located in the leading edge region (a) formed as an inclined surface, it can disperse the stress generated during the charging and discharging of the secondary battery (100), thereby preventing a short circuit caused by deformation.

[0035] The above-mentioned leading edge region (a) may be located at the center of the winding when the negative plate (121), separator (125), positive plate (122), and separator (125) are stacked and wound in a cylindrical shape. The leading edge region (a) may be wound for any one selected from 1 / 4 turn to 1 turn when winding the electrode assembly (120) into a cylinder. Here, if the leading edge region (a) is smaller than 1 / 4 turn, it may be difficult to disperse the stress generated during charging and discharging, and if it is larger than 1 turn, it may cause a decrease in the capacity of the electrode assembly (120). For example, FIG. 4a shows a positive plate (122) with the leading edge region (a) wound in 1 turn, and FIG. 4b shows a positive plate (122) with the leading edge region (a) wound in 1 / 4 turn. That is, as shown in FIGS. 4a and 4b, the positive plate (122) has a leading edge (122c) inclined in the leading edge region (a), so that even if deformation occurs in the center of the winding due to the charging and discharging of the secondary battery (100), stress can be dispersed, thereby preventing a short circuit with the negative plate (121).

[0036] Additionally, the end side (122d) of the anode plate (122) may be parallel to the leading side (122c). That is, the anode plate (122) may be a parallelogram-shaped plate. Here, when manufacturing the anode plate (122), the end side (122d) can be naturally formed into a shape corresponding to the leading side (122c) when the leading side (122c) is cut as an inclined surface from a roll-type anode plate. However, the shape of the end side (122d) may be varied by additional cutting processing. For example, the end side (122d) may be perpendicular to the leading side (122a).

[0037] Here, the leading edge (122c) may be located at the center of the winding in the wound electrode assembly (120), and the trailing edge (122d) may be located at the outermost edge of the wound electrode assembly (120).

[0038] Additionally, an anode tab (127) may be attached to either the first surface of the anode collector plate (124a) or the second surface opposite to the first surface. Additionally, the anode tab (127) may be extended by protruding a certain length from the longitudinal side (122b) of the anode collector plate (124a). The anode tab (127) may be extended approximately perpendicularly from the longitudinal side (122b) of the anode collector plate (124a). Here, the anode tab (127) may be extended to the opposite side (121a) from which the cathode tab (126) protrudes. The anode tab (127) may be attached to the uncoated portion of the anode collector plate (124a) where the anode coating layer (124b) is not coated. Preferably, the positive tab (127) may be attached to a certain area spaced a certain distance from the leading edge (122c) in the longitudinal direction (x) of the positive current collector plate (124a). Of course, the positive current collector plate (124a) may be provided with an uncoated portion where the positive coating layer (124b) is not coated in a certain area spaced a certain distance from the leading edge (122c). However, the location where the positive tab (127) is attached in the present invention may be varied in many ways and is not limited thereto.

[0039] Additionally, an insulating tape (127a) may be further provided to cover the positive tab (127) attached to the positive current collector plate (124a). The insulating tape (127a) may be attached to the positive current collector plate (124a) to cover the portion of the positive tab (127) attached to the positive current collector plate (124a). At this time, the portion of the positive tab (127) that protrudes a certain length above the electrode assembly (120) may be exposed to the outside of the insulating tape (127a). Furthermore, the insulating tape (127a) may be attached to cover a portion of the positive current collector plate (124a) adjacent to the positive tab (127) in the longitudinal direction (x). The positive tab (127) may be made of aluminum, but the present invention is not limited thereto.

[0040] Additionally, the negative tab (126) and the positive tab (127) may be located on the same side of the wound negative plate (121) and the positive plate (122), or on opposite sides of the negative plate (121) and the positive plate (122). Here, the same side may be a side facing the same center of the wound in the wound electrode assembly (120), or a side facing the same outermost edge.

[0041] Additionally, the negative tab (126) of the electrode assembly (120) can be welded to the bottom portion (111) of the case (110). Thus, the case (110) can operate as a negative electrode. Of course, conversely, the positive tab (127) can be welded to the bottom portion (111) of the case (110), and in this case, the case (110) can operate as a positive electrode.

[0042] In addition, a first insulating plate (128) may be interposed between the electrode assembly (120) and the bottom part (111), which is coupled to the case (110) and has a first hole (128a) formed in the center and a second hole (128b) formed on the outer side thereof. This first insulating plate (128) serves to prevent the electrode assembly (120) from making electrical contact with the bottom part (111) of the case (110). In particular, the first insulating plate (128) serves to prevent the positive plate (122) of the electrode assembly (120) from making electrical contact with the bottom part (111). Here, the first hole (128a) serves to allow the gas to move quickly upward when a large amount of gas is generated due to a malfunction of the secondary battery, and the second hole (128b) serves to allow the negative tab (126) to pass through and be welded to the bottom part (111). Additionally, the electrode assembly (120) is further provided with a center pin (not shown) in the form of a hollow circular pipe approximately in the center, so that a large amount of gas generated when the secondary battery malfunctions can be easily discharged through the internal passage of the center pin.

[0043] Additionally, a second insulating plate (129) may be interposed between the electrode assembly (120) and the cap assembly (130), which is coupled to the case (110) and has a first hole (129a) formed in the center and a plurality of second holes (129b) formed on the outer side thereof. This second insulating plate (129) serves to prevent the electrode assembly (120) from making electrical contact with the cap assembly (130). In particular, the second insulating plate (129) serves to prevent the negative plate (121) of the electrode assembly (120) from making electrical contact with the cap assembly (130). Here, the first hole (129a) serves to allow the gas to move quickly to the cap assembly (130) when a large amount of gas is generated due to a malfunction of the secondary battery, and the second hole (129b) serves to allow the positive electrode tab (127) to pass through and be welded to the cap assembly (130). Additionally, the remaining second hole (129b) serves to allow the electrolyte to flow quickly into the electrode assembly (120) during the electrolyte injection process. The electrolyte acts as a transport medium for lithium ions generated by electrochemical reactions in the positive and negative plates inside the battery during charging and discharging.

[0044] The above cap assembly (130) comprises a cap-up (131) having a plurality of through holes (131d), a safety plate (133) installed at the bottom of the cap-up (131), a connecting ring (135) installed at the bottom of the safety plate (133), a cap-down (136) coupled to the connecting ring (135) and having first and second through holes (136a, 136b) formed therein, a sub-plate (137) fixed at the bottom of the cap-down (136) and electrically connected to an anode tab (127), and an insulating gasket (138) that insulates the cap-up (131), the safety plate (133), the connecting ring (135), and the cap-down (136) from the side (111) of the case (110).

[0045] Here, the insulating gasket (138) is substantially formed in a compressed shape between the beading portion (113) and the crimping portion (114) formed on the side (111) of the case (110). Additionally, the through hole (131d) formed in the cap-up (131) and the through hole (136b) formed in the cap-down (136) serve to discharge internal gas to the outside when abnormal internal pressure occurs inside the case (110). Of course, due to this internal pressure, the safety plate (133) is first inverted upward and electrically separated from the sub-plate (137), and then the safety plate (133) is torn and the internal gas is released to the outside.

[0046] Referring to FIG. 5, an exploded perspective view is shown illustrating another example of the electrode assembly of the secondary battery illustrated in FIG. 1a to 1c before it is wound. As shown in FIG. 5, the electrode assembly (220) comprises a negative electrode plate (121) in which a negative electrode active material (123b) is coated on a negative electrode current collector plate (123a), a positive electrode plate (222) in which a positive electrode active material (224b) is coated on a negative electrode current collector plate (223a), and a separator (125) interposed between the negative electrode plate (121) and the positive electrode plate (222) to prevent a short circuit between the negative electrode plate (121) and the positive electrode plate (222) and to allow only the movement of lithium ions.

[0047] The negative plate (121) and separator (125) of the electrode assembly (220) are identical to the electrode assembly (120) shown in FIGS. 2a and 2b. Therefore, the following description will focus on the positive plate (222) of the electrode assembly (220), which is different from the electrode assembly (120).

[0048] The anode plate (222) has an anode coating layer (224b), which is an active material made of a transition metal oxide, coated on both sides of an anode current collector plate (224a), which is a plate-shaped metal foil made of aluminum (Al). The anode plate (222) may have a plate shape that extends along the longitudinal direction (x). The anode plate (222) may include a side (222a) that extends along the longitudinal direction (x) and a side (222b) opposite to the side. Additionally, the anode plate (222) may further include a leading side (222c) and a trailing side (222d) connecting the side (222a) and the side (222b). The side (222a) and the side (222b) of the anode plate (222) may be parallel to the side (121a) and the side (121b) of the negative plate (121). Additionally, the leading edge (222c) of the positive plate (222) may be shorter in the longitudinal direction (x) from the center of the winding of the electrode assembly (220) compared to the leading edge (121c) of the negative plate (121). That is, the leading edge (121c) of the negative plate (121) may be extended longer in the direction of the center of the winding compared to the leading edge (222c) of the positive plate (222).

[0049] The leading edge (222c) of the above positive plate (222) may include a first leading edge (222ca) inclined to have an acute or obtuse angle with one side (222a) and a second leading edge (222cb) inclined to have an acute or obtuse angle with the other side (222b). Here, the first leading edge (222ca) may be connected to the end of the one side (222a), and the second leading edge (222cb) may be connected to the end of the other side (222b).

[0050] Here, if the first end side (222ca) has an acute angle with the first side (222a), the second end side (222cb) may have an acute angle with the other side (222b). Of course, if the first end side (222ca) has an obtuse angle with the first side (222a), the second end side (222cb) may have an obtuse angle with the other side (222b). For example, the angle between the first end side (222ca) and the first side (222a) and the angle between the second end side (222cb) and the other side (222b) may be the same.

[0051] Additionally, the end of the first end edge (222ca) is connected to the end of the second end edge (222cb). That is, the end edge (222c) may have a bent portion (222cc) at the part where the first end edge (222ca) and the second end edge (222cb) are connected. Preferably, the lengths of the first end edge (222ca) and the second end edge (222cb) may be the same, and the bent portion (222cc) may be located at the center of the end edge (222c). However, the lengths of the first end edge (222ca) and the second end edge (222cb) are not limited in the present invention.

[0052] The leading edge (222c) of the positive plate (222) may be located within the leading edge region (a). Here, the positive plate (222) in the leading edge region (a) may have the shape of two right triangles, and the first leading edge (222ca) and the second leading edge (222cb) may each be the hypotenuses of the two right triangles. Here, the stress generated during the charging and discharging of the secondary battery (100) can be dispersed by the two leading edge (222ca) and the second leading edge (222cb) that are inclined with respect to the one side (222a) and the other side (222b) located in the leading edge region (a).

[0053] In such an electrode assembly (220), if the leading edge (222c) is perpendicular to the leading edge (222a) and the other edge (222b), stress is concentrated in the deformed portion, causing the positive plate (222) to penetrate the separator (125) and a short circuit may occur with the negative plate (121). That is, since the positive plate (222) of the secondary battery (100) has a first leading edge (222ca) and a second leading edge (222cb) located in the leading area (a) formed as inclined surfaces, the stress applied to the deformed portion during charging and discharging of the secondary battery (100) can be dispersed, thereby preventing a short circuit caused by deformation.

[0054] The leading edge region (a) may be located at the center of the winding when the negative plate (121), separator (125), positive plate (222), and separator (125) are stacked and wound in a cylindrical shape. The leading edge region (a) may be wound for any one selected from 1 / 4 turn to 1 turn when winding the electrode assembly (220) into a cylinder. Here, if the leading edge region (a) is smaller than 1 / 4 turn, it may be difficult to disperse the stress generated during charging and discharging, and if it is larger than 1 turn, it may cause a decrease in the capacity of the electrode assembly (220).

[0055] In addition, the end side (222d) of the positive plate (222) and the leading side (222c) can be formed with corresponding shapes. As shown in FIG. 5, in the leading region (a), if the first leading side (222ca) has an acute angle with one side (222a) and the second leading side (222cb) has an acute angle with the other side (222b), then the end side (222d) has the first leading side (222da) having an obtuse angle with one side (222a) and the second leading side (222db) having an obtuse angle with the other side (222b). Of course, conversely, the leading side (222c) may have the shape of the leading side (222d) of FIG. 5, and the leading side (222d) may have the shape of the leading side (222c) of FIG. 5.

[0056] Additionally, the first end side (222da) may be connected to the first side (222a), and the second end side (222db) may be connected to the other side (222b). Additionally, a bend (222dc) may be provided at the portion where the first end side (222da) and the second end side (222db) are connected. Preferably, the lengths of the first end side (222da) and the second end side (222db) may be equal, and the bend (222dc) may be located at the center of the end side (222d). However, the lengths of the first end side (222da) and the second end side (222db) are not limited in the present invention.

[0057] Here, the end edge (222d) can be naturally formed into a corresponding shape when the end edge (222c) of the roll-type anode plate is cut to have a first end edge (222ca), a second end edge (222cb), and a bent portion (222cc) during the manufacture of the anode plate (222). However, the end edge (222d) can be varied by additional cutting processing.

[0058] Here, the leading edge (222c) may be located at the center of the winding in the wound electrode assembly (220), and the trailing edge (222d) may be located at the outermost edge of the wound electrode assembly (220).

[0059] Additionally, an anode tab (127) may be attached to either the first surface of the anode collector plate (224a) or the second surface opposite to the first surface. Additionally, the anode tab (127) may be extended by protruding a certain length from the longitudinal side (x) of the anode collector plate (224a). The anode tab (127) may be extended approximately perpendicularly from the longitudinal side (x) of the anode collector plate (224a). Here, the anode tab (127) may be extended to the opposite side (121a) from which the cathode tab (126) protrudes. The anode tab (127) may be attached to the uncoated portion of the anode collector plate (224a) where the anode coating layer (224b) is not coated. Preferably, the positive tab (127) may be attached to a certain area spaced a certain distance from the leading edge (222c) in the longitudinal direction (x) of the positive current collector plate (224a). Of course, the positive current collector plate (224a) may be provided with an uncoated portion where the positive coating layer (224b) is not coated in a certain area spaced a certain distance from the leading edge (222c). However, the location where the positive tab (127) is attached in the present invention may be varied in many ways and is not limited thereto.

[0060] Additionally, an insulating tape (127a) may be further provided to cover the positive tab (127) attached to the positive current collector plate (224a). The insulating tape (127a) may be attached to the positive current collector plate (224a) to cover the portion of the positive tab (127) attached to the positive current collector plate (224a). At this time, the portion of the positive tab (127) that protrudes a certain length above the electrode assembly (220) may be exposed to the outside of the insulating tape (127a). Furthermore, the insulating tape (127a) may be attached to cover a portion of the positive current collector plate (224a) adjacent to the positive tab (127) in the longitudinal direction (x). The positive tab (127) may be made of aluminum, but the present invention is not limited thereto.

[0061] Additionally, the negative tab (126) and the positive tab (127) may be located on the same side of the wound negative plate (121) and the positive plate (222), or on opposite sides of the negative plate (121) and the positive plate (222). Here, the same side may be a side facing the same center of the wound in the wound electrode assembly (220), or a side facing the same outermost edge.

[0062] Additionally, the negative tab (126) of the electrode assembly (220) can be welded to the bottom portion (111) of the case (110). Thus, the case (110) can operate as a negative electrode. Of course, conversely, the positive tab (127) can be welded to the bottom portion (111) of the case (110), and in this case, the case (110) can operate as a positive electrode.

[0063] The above description is merely one embodiment for implementing an electrode assembly and a secondary battery including the same according to the present invention. The present invention is not limited to the above-described embodiment, and the technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the gist of the invention as claimed in the following patent claims. Explanation of the symbols

[0064] 100: Secondary battery 110: Case 120, 220: Electrode assembly 121: Cathode plate 122, 122: Positive plate 125: Separator 130: Cap assembly

Claims

Claim 1 An electrode assembly formed by winding a laminate of the cathode plate, the separator, and the anode plate, wherein a cathode coating layer is formed on a cathode collector plate and the cathode plate is a rectangular plate; an anode plate wherein an anode coating layer is formed on an anode collector plate; and a separator interposed between the anode plate and the cathode plate, wherein the anode plate comprises: a side extending along the longitudinal direction; a side extending along the longitudinal direction opposite to the side extending from Claim 2 An electrode assembly according to claim 1, wherein the leading edge is located within a leading edge region, the positive plate within the leading edge region is in the shape of a right triangle, and the leading edge is the hypotenuse of the right triangle. Claim 3 In claim 2, the leading edge region is an electrode assembly wound by any one of 1 / 4 turn to 1 turn when the electrode assembly is wound into a cylinder. Claim 4 An electrode assembly according to claim 1, wherein the longitudinal side is parallel to the leading side, and the positive plate is a parallelogram-shaped plate. Claim 5 An electrode assembly according to claim 1, wherein the cathode plate is a rectangular plate extending along the longitudinal direction and comprising: one side and the other side parallel to one side of the anode plate; a leading edge connecting one side of the cathode plate and the other side of the cathode plate and located at the center of the winding of the wound electrode assembly; and a trailing edge connecting one side of the cathode plate and the other side of the cathode plate and located at the outermost edge of the electrode assembly wound opposite to the leading edge of the cathode plate. Claim 6 In claim 1, the electrode assembly in which the leading edge of the cathode plate extends further along the longitudinal direction toward the center of the winding compared to the leading edge of the anode plate. Claim 7 An electrode assembly is formed by winding a laminate of the cathode plate, the separator, and the anode plate, wherein the cathode plate has a cathode coating layer formed thereon and the cathode plate is a rectangular plate; an anode plate has an anode coating layer formed thereon on the anode plate; and a separator interposed between the anode plate and the cathode plate, wherein the anode plate comprises: a side extending along the longitudinal direction; a side extending along the longitudinal direction opposite to the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending from the side extending thereon; An electrode assembly comprising a second end edge that is inclined to have an acute angle from the other end edge and connected to the end of the first end edge, and having a bent portion at the part where the first end edge and the second end edge are connected, wherein the bent portion is located at the center of the end edge. Claim 8 An electrode assembly is formed by winding a laminate of the cathode plate, the separator, and the anode plate, wherein the cathode plate has a cathode coating layer formed thereon and the cathode plate is a rectangular plate; an anode plate has an anode coating layer formed thereon on the anode plate; and a separator interposed between the anode plate and the cathode plate, wherein the anode plate comprises: a side extending along the longitudinal direction; a side extending along the longitudinal direction opposite to the side extending from thereon; An electrode assembly comprising a second end edge that is inclined at an obtuse angle from the other end edge and connected to the end of the first end edge, and having a bent portion at the part where the first end edge and the second end edge are connected, wherein the bent portion is located at the center of the end edge. Claim 9 In claim 7 or 8, the bent portion is an electrode assembly located at the center of the leading edge. Claim 10 An electrode assembly according to claim 7 or 8, wherein the end edge of the anode plate has a shape corresponding to the leading edge. Claim 11 A secondary battery comprising: an electrode assembly described in any one of claims 1 to 8; a case having an internal space in which the electrode assembly contains an electrolyte in the internal space; and a cap plate coupled to the upper part of the case to seal the case.

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