Secondary battery

Abstract

The present disclosure relates to a secondary battery, and a technical problem to be solved is to provide a secondary battery in which an anti-corrosion coating is applied to a welded portion between a negative electrode current collector plate and a case, so as to improve durability. To this end, the present invention provides: an electrode assembly having a first electrode plate, a second electrode plate, and a separator; a case in which the electrode assembly is accommodated; a negative electrode current collector plate that is welded to the case and electrically connected to the electrode assembly; and an anti-corrosion part applied to a connection area in which the negative electrode current collector plate is welded to the case, so as to prevent corrosion.

Description

secondary battery

[0001] The present disclosure relates to a secondary battery.

[0002] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

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

[0004] The present invention relates to a secondary battery capable of improving durability by applying an anti-rust coating to the welding area of ​​a negative electrode collector plate and a case.

[0005] In addition, the present invention relates to a secondary battery that can extend reliability and lifespan by preventing rust formation in a negative electrode collector plate and a case.

[0006] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0007] An exemplary secondary battery according to one embodiment of the present invention for solving the above technical problem includes an electrode assembly having a first electrode plate, a second electrode plate, and a separator, a case in which the electrode assembly is accommodated inside, a negative electrode collector plate that is fixed to the case by welding and electrically connected to the electrode assembly, and a rust prevention part that is applied to a connection portion of the negative electrode collector plate welded to the case to prevent rust from occurring.

[0008] In some examples, the insulation may use at least one of polymers PI, PAI, silicone resin, and epoxy resin.

[0009] In some examples, the insulation layer may be formed at the weld of the cathode current collector.

[0010] In some examples, the insulation layer may be formed at the welded portion of the negative electrode collector and at the negative electrode collector plate in contact with the case.

[0011] In some examples, the insulation layer may be formed around the opening of the case where the cathode current collector is installed in contact with it.

[0012] In some examples, the number of welds between the cathode current collector and the case may be 3 to 6.

[0013] In some examples, the number of coatings on the insulation may be equal to the number of welds.

[0014] In some examples, the rust inhibitor may be applied to the cathode current collector and then UV cured.

[0015] In some examples, the time required for UV curing may be 5 to 12 seconds.

[0016] In some examples, the temperature when UV curing can be between 100°C and 170°C.

[0017] In some examples, the coating thickness of the soundproofing part may be 3 to 10 um.

[0018] In some examples, the inhibitor may be applied to the cathode current collector by spraying.

[0019] An exemplary secondary battery according to one embodiment of the present invention for solving the above technical problem may include an electrode assembly including a first electrode plate, a second electrode plate, and a separator, a case in which the electrode assembly is accommodated inside, a negative electrode collector plate that is fixed to the case by welding and electrically connected to the electrode assembly, a rust prevention part that is applied to a connection portion of the negative electrode collector plate welded to the case to prevent rust, a vent plate that shields an open entrance of the case, and a cap gasket that is installed in a shape that surrounds the outer periphery of the vent plate and blocks electrical connection between the negative electrode collector plate and the case and the vent plate.

[0020] In some examples, the negative electrode collector plate may include a body portion installed in contact with the second electrode plate, an extension portion extending outwardly from the body portion and installed in contact with the second electrode plate together with the body portion, and a wing portion extending outwardly from the extension portion and being welded to the case.

[0021] In some examples, the wing section may include a wing body extending from the body section and a fixed wing extending in an arc shape from an end of the wing body and secured to the case by welding.

[0022] In some examples, the rust barrier may be formed at the welded portion of the fixed wing or along the entire fixed wing.

[0023] In some examples, the soundproofing portion may be formed in the body portion, the extension portion, and the wing portion.

[0024] In some examples, the wing section may include a wing body extending from the body section and a fixed wing extending in an arc shape from an end of the wing body and secured to the case by welding.

[0025] In some examples, the soundproofing portion may be formed on a fixed wing facing the wing body.

[0026] In some examples, the anti-corrosion unit may include a first coating member in which an anti-corrosion coating is applied to a fixed wing facing the wing body, and a second coating member in which an anti-corrosion coating is applied around an inlet of a case where the fixed wing is not located.

[0027] In some examples, the insulation may use at least one of polyvinylidene fluoride (PVDF), epoxy resins, polyurethane, ceramic coating, and polytetrafluoroethylene (PTFE).

[0028] According to the present invention, the durability of a secondary battery can be improved by applying a rust-preventive coating to the welded portion of a negative electrode current collector plate where rust easily occurs.

[0029] In addition, the present invention can prevent rust from occurring in the negative electrode collector and case, thereby extending reliability and lifespan and reducing maintenance costs.

[0030] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0031] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0032] Figure 1 is a perspective view of an exemplary secondary battery according to the present invention.

[0033] Figure 2 is a cross-sectional view of an exemplary secondary battery according to the present invention.

[0034] Figure 3 is a bottom view showing a state in which a rust-preventive coating is formed on a welded portion of an exemplary negative electrode collector plate according to the present invention.

[0035] Figure 4 is a bottom view showing a state in which a weld is formed on an exemplary negative electrode collector plate according to the present invention.

[0036] FIG. 5 is a partial cutaway perspective view showing an exemplary negative electrode collector plate according to the present invention fixed to a case.

[0037] Figure 6 is a perspective view illustrating an exemplary negative electrode collector plate according to the present invention.

[0038] Figure 7 is a plan view illustrating an exemplary negative electrode collector plate according to the present invention.

[0039] Figure 8 is a bottom view showing a state in which a rust-preventive coating portion is formed on a fixed wing of an exemplary negative electrode collector plate according to the present invention.

[0040] Figure 9 is a bottom view showing a state in which a rust-preventing coating is formed on the fixed wing and beading portion of an exemplary negative electrode collector plate according to the present invention.

[0041] Figure 10 is a bottom view showing a state in which an anti-rust coating is formed on the entire surface of an exemplary negative electrode collector plate according to the present invention.

[0042] Fig. 11 is a bottom view showing a state in which an anti-rust coating portion is formed at the center of an exemplary fixed wing according to the present invention.

[0043] Fig. 12 is a bottom view showing a state in which a rust-preventing coating is formed at the center of an exemplary fixed wing and the inlet of the case according to the present invention.

[0044] FIGS. 13A and 13B are perspective views illustrating a battery pack including an exemplary secondary battery according to the present invention.

[0045] FIGS. 14A and 14B are perspective and side views illustrating a vehicle including an exemplary battery pack according to the present invention.

[0046] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0047] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0048] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0049] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0050] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0051] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0052] Any configuration being placed “on top (or bottom)” of a component or “on top (or bottom)” of a component may mean not only that any configuration is placed in contact with the top (or bottom) of the component, but also that other configurations may be interposed between the component and any configuration placed on (or under) the component.

[0053] Additionally, when it is described that a component is “connected,” “coupled,” or “connected” to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be “interposed” between the components, or that each component may be “connected,” “coupled,” or “connected” through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0054] When reference is made throughout the specification to “A and / or B,” this means A, B, or A and B, unless otherwise stated. In other words, “and / or” includes all or any combination of the listed items. When reference is made to “C through D,” this means C or more and D or less, unless otherwise stated.

[0055] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0056] FIG. 1 is a perspective view of an exemplary secondary battery (100) according to the present invention, and FIG. 2 is a cross-sectional view of an exemplary secondary battery (100) according to the present invention. As illustrated in FIGS. 1 and 2, the exemplary secondary battery (100) according to the present invention may include a case (110), an electrode assembly (120), a negative electrode current collector (130), a positive electrode current collector (146), a positive electrode terminal (144), a vent plate (160), a weld (190), and a rust-preventing portion (180). In some examples, the exemplary secondary battery (100) may include at least one of an insulating gasket (171), an upper insulating member (172), a cap gasket (173), and an inner gasket (174). In the present invention, the secondary battery (100) may be referred to as a cylindrical secondary battery (100) or a battery.

[0057] The case (110) can be modified in various ways within the technical concept of accommodating the electrode assembly (120) inside. The case (110) accommodates the electrode assembly (120) and the electrolyte, and together with the vent plate (160), can form the outer shape of the secondary battery (100). The case (110) may include or be referred to as a can, a housing, or an outer material. The case (110) may include a case upper wall (111) having a generally circular shape and a case side wall (112) having a cylindrical shape extending downward from the case upper wall (111). In some examples, the case (110) may be configured in various shapes, such as a pouch shape, in addition to a circular shape. In addition, the case (110) may include a metal such as steel, nickel-plated steel, stainless steel, a steel alloy, aluminum, an aluminum alloy, a cooling sheet for deep drawing (SPCE), or a laminate film or plastic that constitutes the pouch. The case side wall (112) may be provided with a beading portion (113) that is recessed toward the inside of the case (110). The lower end of the case side wall (112) may be provided with a crimping portion (114) that is curved toward the inside of the case (110). When both the beading portion (113) and the crimping portion (114) are included in the case (110), the crimping portion (114) is positioned at the lower side of the beading portion (113). The beading portion (113) may suppress movement of the electrode assembly (120) together with the case upper wall (111). The crimping portion (114) may press the edge of the vent plate (160) through the cap gasket (173) to firmly fix the vent plate (160).

[0058] An electrode assembly (120) may be accommodated inside a case (110) together with an electrolyte. The electrode assembly (120) may include or be referred to as an electrode group, an electrode body, or a jelly roll. The electrode assembly (120) may include a first electrode plate (121), a second electrode plate (122), and a separator (123) between the first electrode plate (121) and the second electrode plate (122), and may be wound in a cylindrical shape. In some examples, a hollow core (124) may be provided in the center of the electrode assembly (120) in a vertical longitudinal direction (vertically in the vertical direction with reference to FIG. 2). In some examples, a center pin may be coupled to the core (124).

[0059] The first electrode plate (121) may include a first substrate (1211) and a first active material layer (1212) positioned on the first substrate (1211). A first non-conductive portion or first tab (1213) of the first substrate (1211) where the first active material layer (1212) is not positioned may extend outward (e.g., upward), and the first tab (1213) may be electrically connected to the positive electrode current collector (146). In the present invention, the first tab (1213) may be referred to as a first non-conductive portion or a positive electrode substrate tab.

[0060] The second electrode plate (122) may include a second substrate (1221) and a second active material layer (1222) positioned on the second substrate (1221). A second non-conductive portion or second tab (1223) of the second substrate (1221) where the second active material layer (1222) is not positioned may extend outward (e.g., downward), and the second tab (1223) may be electrically connected to the negative electrode current collector (130). In some examples, the first tab (1213) and the second tab (1223) may extend in opposite directions. In the present invention, the second tab (1223) may be referred to as a second non-conductive portion or a negative electrode substrate tab.

[0061] The first electrode plate (121) can function as an anode. In this case, the first substrate (1211) can be composed of, for example, aluminum foil, and the first active material layer (1212) can include, for example, a transition metal oxide. The second electrode plate (122) can function as an anode. In this case, the second substrate (1221) can be composed of, for example, copper foil or nickel foil, and the second active material layer (1222) can include, for example, graphite and / or silicon.

[0062] The separator (123) can prevent short circuiting between the first electrode plate (121) and the second electrode plate (122) while allowing movement of lithium ions. In some examples, the separator (123) can be positioned on opposite sides of the first electrode plate (121), or on opposite sides of the second electrode plate (122).

[0063] The positive terminal (144) may be coupled to the case (110) and electrically connected to the electrode assembly (120). In one embodiment of the present invention, the positive terminal (144) may include or be referred to as a rivet, a terminal, or a rivet terminal. The positive terminal (144) may include a rivet post (141), a rivet head (142), and a rivet leg (143). The rivet post (141) may be coupled to the case upper wall (111) while penetrating the case upper wall (111). The rivet head (142) may be connected to the upper end of the rivet post (141) and may be positioned on the upper side of the case upper wall (111). The rivet leg (143) may be connected to the lower end of the rivet post (141) and may be positioned on the lower side of the case upper wall (111). In some examples, an insulating gasket (171) may be interposed between the rivet post (141) and the case top wall (111). In some examples, an upper insulating member (172) may be interposed between the rivet head (142) and the upper side of the case top wall (111). In some examples, an inner gasket (174) may be installed between the rivet leg (143) and the lower side of the case top wall (111). The inner gasket (174) is installed between the positive terminal (144) and the case (110), and various modifications are possible within the technical concept of blocking the electrical connection between the positive terminal (144) and the case (110).

[0064] In some examples, the insulating gasket (171), the upper insulating member (172), and the inner gasket (174) may be provided separately. The insulating gasket (171), the upper insulating member (172), and the inner gasket (174) may not be integral. In some examples, the insulating gasket (171) and the upper insulating member (172) may be integrally formed, and the inner gasket (174) may be formed as a separate member. In some examples, the insulating gasket (171), the upper insulating member (172), and the inner gasket (174) may be integrally formed. In some examples, the insulating gasket (171) and the inner gasket (174) may be integrally formed, and the upper insulating member (172) may be formed as a separate member.

[0065] In some examples, the rivet post (141) may include a rivet recess (1411). In some examples, the rivet leg (143) may be electrically connected to the positive collector plate (146). The electrical connection may be achieved by various methods, such as by welding the positive collector plate (146) to the rivet leg (143). In some examples, the rivet leg (143) and the positive collector plate (146) may be formed integrally. When the rivet leg (143) and the positive collector plate (146) are formed integrally, the number of parts is reduced, thereby reducing the time required for the production process. In some examples, the rivet leg (143) may be welded to the positive collector plate (146) by irradiating a laser beam through the rivet recess (1411). In some examples, after the welding process, the rivet recess (1411) may be filled with metal or closed with a metal plate. The positive terminal (144) may comprise aluminum, an aluminum alloy, copper, a copper alloy, nickel, or a nickel alloy. In this way, the positive terminal (144) may perform a function of electrically connecting to an external device. In some examples, the case top wall (111) may also perform a function of electrically connecting to an external device.

[0066] By installing the insulating gasket (171) and the upper insulating member (172), the gap between the case (110) and the positive terminal (144) is blocked, thereby preventing leakage of the electrolyte.

[0067] An inner gasket (174) may be interposed between the case (110) and the positive terminal (144). The inner gasket (174) may be in contact with or adhered to the case upper wall (111). In some examples, a portion of the inner gasket (174) may be in contact with or adhered to the rivet post (141).

[0068] The positive electrode collector (146) may be connected to the first tab (1213) of the electrode assembly (120). The positive electrode collector (146) may include or be referred to as a first current collector, a first conductor, or a first conductive plate. In some examples, the positive electrode collector (146) may be provided in a generally circular disk shape. A plurality of first tabs (1213) extending / protruding from the electrode assembly (120) may be electrically connected to a lower surface of the positive electrode collector (146). In some examples, the first tabs (1213) may be bent inwardly toward the core (124) or outwardly away from the core (124) and laser welded to the lower surface of the positive electrode collector (146). The positive electrode collector (146) may include aluminum, an aluminum alloy, copper, a copper alloy, nickel, or a nickel alloy.

[0069] The vent plate (160) can be modified in various ways within the technical concept of shielding the open entrance of the case (110). The vent plate (160) can be coupled by interposing a cap gasket (173) between the beading portion (113) and the crimping portion (114) of the case (110). The vent plate (160) may include or be referred to as a cap plate, a cap assembly, a safety vent, a conductive plate, or a sealing plate. In some examples, instead of providing the beading portion (113) and the crimping portion (114), the vent plate (160) may be directly welded to the case side wall (112), or the vent plates (160) may be coupled to the case side wall (112) in a curling or seaming manner.

[0070] In some examples, the vent plate (160) may further include a vent notch (161) that is provided relatively thinly on the upper surface. In some examples, the vent plate (160) may include a peripheral region (162) that is sandwiched between the beading portion (113) and the crimping portion (114), an inner region (163) that is connected to the peripheral region (162) and is lower than the peripheral region (162), and a central region (164) that is connected to the inner region (163) and is higher than the inner region (163). The vent notch (161) may be provided on the inner region (163). In some examples, the central region (164) may be closer to the electrode assembly (120) than the peripheral region (162) and the inner region (163). This vent notch (161) is ruptured to release internal gas when the internal pressure of the secondary battery (100) is higher than a reference pressure. The vent plate (160) may be composed of iron, nickel-plated iron, stainless steel, aluminum, or an aluminum alloy. In some examples, the case (110) and the vent plate (160) coupled thereto may be collectively referred to as the case (110).

[0071] The cap gasket (173) is installed in a shape that wraps around the outer periphery of the vent plate (160). The cap gasket (173) blocks the electrical connection between the negative electrode collector (130) and the vent plate (160), and can be variously modified within the technical concept of blocking the electrical connection between the case (110) and the vent plate (160). The cap gasket (173) according to one embodiment of the present invention may be installed between the vent plate (160) and the wing portion (136) of the negative electrode collector (130). Since the cap gasket (173) is installed in contact with the rust-preventing portion (180), it prevents the rust-preventing portion (180) and the welding portion (190) where the rust-preventing portion (180) is installed from coming into contact with the air, thereby reducing or preventing the occurrence of rust. The cap gasket (173) is installed in a shape that wraps around the outer edge of the vent plate (160). The cross-section of the cap gasket (173) is shaped like the letter “ㄷ” and is joined to the edge of the vent plate (160). The upper side of the cap gasket (173) is in contact with the wing portion (136) located on the lower side of the beading portion (113), so that the wing portion (136) and the anti-corrosion portion (180) coated on the surface of the wing portion (136) can be prevented from coming into contact with the air.

[0072] FIG. 3 is a bottom view illustrating a state in which a rust-proof part (180) is formed on a welded part (190) of an exemplary negative electrode collector plate (130) according to the present invention, and FIG. 4 is a bottom view illustrating a state in which a welded part (190) is formed on an exemplary negative electrode collector plate (130) according to the present invention. As illustrated in FIGS. 2 to 4, the negative electrode collector plate (130) is fixed to the case (110) by welding and various modifications are possible within the technical concept of being electrically connected to the electrode assembly (120). The negative electrode collector plate (130) may be connected to the second tab (1223) of the electrode assembly (120). The negative electrode collector plate (130) may include or be referred to as a second current collector, a second conductor, or a second conductive plate. In some examples, the negative electrode collector plate (130) may be provided in a substantially circular disk shape. A plurality of second tabs (1223) extending / protruding from the electrode assembly (120) may be electrically connected to the upper surface of the negative electrode collector (130). In some examples, the second tabs (1223) may be bent inwardly toward the core (124) or outwardly away from the core (124), and may extend in a straight direction extending vertically. The second tabs (1223) may be laser welded to the upper surface of the negative electrode collector (130). The negative electrode collector (130) may include copper, a copper alloy, nickel, a nickel alloy, aluminum, or an aluminum alloy. In some examples, the negative electrode collector (130) may be electrically connected to the case (110) by being sandwiched between the beading portion (113) and the cap gasket (173).

[0073] A negative electrode collector plate (130) according to one embodiment of the present invention may include a body portion (132) installed in contact with a second electrode plate (122), an extension portion (134) extending outwardly from the body portion (132) and installed in contact with the second electrode plate (122) together with the body portion (132), and a wing portion (136) extending outwardly from the body portion (132) in a state spaced apart from the extension portion (134) and fixed to a case (110) by welding. In some examples, the wing portion (136) may include a wing body (137) extending from the body portion (132) and a fixed wing (138) extending in an arc shape from an end of the wing body (137) and fixed to the case (110) by welding. In some examples, the soundproofing portion (180) may be formed on the welded portion (190) of the fixed wing (138) or on the entire fixed wing (138).

[0074] Fig. 6 is a perspective view illustrating an exemplary negative electrode collector plate (130) according to the present invention, and Fig. 7 is a plan view illustrating an exemplary negative electrode collector plate (130) according to the present invention. As illustrated in Figs. 2, 6, and 7, the body portion (132) may be formed in a circular plate shape corresponding to the lower portion of the electrode assembly (120). In addition, the body portion (132) may be formed in a plate shape of various shapes other than a circular shape. Since the upper surface of the body portion (132) is fixed by welding while in contact with the lower portion of the electrode assembly (120), the body portion (132) can be fixed to the second tab (1223) exposed to the lower portion of the electrode assembly (120) and electrically connected thereto.

[0075] The extension portion (134) and the wing portion (136) are provided in multiples, and the extension portions (134) and the wing portions (136) can be installed alternately along the direction of the circle. According to one embodiment of the present invention, the number of extension portions (134) and wing portions (136) is the same, and the body portion (132) can be divided into numbers corresponding to the extension portions (134). For example, the extension portions (134) and the wing portions (136) are provided in fours each, and the extension portions (134) and the wing portions (136) can be installed alternately along the direction of the circle.

[0076] The wing portion (136) can be transformed into various shapes within the technical concept of extending downward from the edge of the body portion (132) and being fixed to the case (110). A plurality of wing portions (136) can be provided so as to be spaced apart from each other along the edge of the body portion (132).

[0077] For example, the wing portion (136) is illustrated as having four wings symmetrically arranged around the body portion (132), but the present invention is not limited thereto. The wing portion (136) may extend in a shape that bends downward multiple times from the edge of the body portion (132).

[0078] A wing member (136) according to one embodiment of the present invention includes a wing body (137) extending outwardly from a body member (132) and a fixed wing (138) extending from the wing body (137) and fixed to a case (110) by welding. The fixed wing (138) may extend in an arcuate direction from an end of the wing body (137).

[0079] FIG. 5 is a partial cutaway perspective view illustrating an exemplary negative electrode collector plate (130) according to the present invention fixed to a case (110). As illustrated in FIG. 5, the wing body (137) may have a shape that is sequentially bent in the outer and upper directions of the body portion (132). As another example, the wing body (137) may be connected to the fixed wing (138) by extending to the outer side of the body portion (132) without a separate bent or stepped shape. The wing portion (136) forms a passage for current to flow between the second electrode plate (122) of the electrode assembly (120) and the case (110).

[0080] The anti-rust portion (180) illustrated in Fig. 3 is applied to the connection portion of the negative electrode collector plate (130) welded to the case (110) and can be modified in various ways within the technical concept of preventing rust. Since the fixed wing (138) of the negative electrode collector plate (130) is fixed by welding while in contact with the case (110), a weld portion (190) is formed.

[0081] The number of welds between the negative electrode collector plate (130) and the case (110) may be 3 to 6. That is, the negative electrode collector plate (130) is provided with 3 to 6 fixed wings (138), and the number of welds (190) that fix the fixed wings (138) to the case (110) may also be the same as the number of fixed wings (138). According to one embodiment of the present invention, the negative electrode collector plate (130) has four wing parts (136), and the extension parts (134) are configured with four. In addition, the weld parts (190) in which welding is performed while the fixed wings (138) of the wing parts (136) are in contact with the case (110) are also formed on each fixed wing (138), so the number of weld parts (190) is also 4. Each welded portion (190) can be installed spaced apart at 90° intervals. The number and the spaced angle of the welded portion (190), the wing portion (136), and the extension portion (134) are not limited as described above, and various modifications may be possible as needed. The fixed wing (138) of the negative electrode collector plate (130) is fixed to the case (110) by welding while in contact with the case (110). Since the case (110) and the negative electrode collector plate (130) are made of different metal materials, the welding that fixes the negative electrode collector plate (130) to the case (110) is a double metal welding. The material of the case (110) is iron, which is prone to corrosion and oxidation. Therefore, a rust-preventing portion (180) is formed by applying a rust-preventing coating or coating to the welded portion (190) where corrosion may easily occur. In order to prevent corrosion of the welded portion (190), a rust-preventing portion (180) is formed by coating the welded portion (190) with a polymer material. The rust-preventing portion (180) may include or be referred to as a rust-preventing coating portion. By installing the rust-preventing portion (180), rust generation of the negative electrode current collector (130) and the case (110), including the welded portion (190), can be prevented, and the generation of foreign substances can be minimized, thereby extending the life of the secondary battery (100) and improving operational reliability.

[0082] When selecting a material for the insulation layer (180), the chemical stability of the material, minimization of interaction with the electrolyte, coating efficiency, and economy must be considered.

[0083] The rust-proofing part (180) can use at least one of polymer-based PI, PAI, silicone resin, polyvinylidene fluoride (PVDF), polyurethane, ceramic coating, polytetrafluoroethylene (PTFE), and epoxy resins. The rust-proofing part (180) can use a resin that is dryable, heat-resistant, adhesive, flame-retardant, and chemical-resistant. The polymer-based PI is polyimide, and has heat stability, chemical resistance, and electrical insulation. Chemical resistance is a property that is suitable for use in various environments because it has high resistance to various compounds. PAI is polyamide-imide, and has heat stability, chemical resistance, and electrical insulation.

[0084] Polyvinylidene fluoride (PVF) possesses excellent chemical resistance and exhibits excellent resistance to electrolytes in lithium-ion batteries. Furthermore, PVF can form an effective barrier to protect the negative electrode current collector from electrolyte chemicals.

[0085] Epoxy resins offer high adhesion and chemical resistance and can be widely used as anti-corrosion coatings.

[0086] Polyurethane coatings provide excellent durability and have chemical and water resistance properties, which help prevent corrosion caused by electrolytes.

[0087] Ceramic coatings are highly chemically stable and highly resistant to heat and electricity. Ceramics maintain stable performance when in contact with the battery's electrolyte.

[0088] Polytetrafluoroethylene has excellent chemical resistance, minimizes reaction with electrolytes, and can provide excellent rust prevention performance.

[0089] According to one embodiment of the present invention, the rust-preventing portion (180) may be formed on the welded portion (190) of the negative electrode current collector (130). The rust-preventing portion (180) is formed in a shape that covers the welded portion (190). In some examples, the rust-preventing portion (180) may be formed by applying an rust-preventing solution to the negative electrode current collector (130) and then UV curing. The time required for UV curing may be 5 to 12 seconds. In addition, the temperature at the time of UV curing may be 100°C to 170°C. The coating thickness of the rust-preventing portion (180) may be 3 to 10 μm. In some examples, the rust-preventing solution may be applied to the negative electrode current collector (130) by spraying.

[0090] Welding is performed while the fixed wing (138) of the negative electrode collector (130) is in contact with the case (110), and after the welded portion (190) is formed, an anti-rust solution is sprayed onto the welded portion (190) and then UV cured to form the anti-rust portion (180).

[0091] UV curing (Ultraviolet curing) is a process in which a compound hardens into a solid state by exposure to short-wavelength ultraviolet (UV) light. UV curing is accomplished using UV lamps or LEDs.

[0092] The rust inhibitor, which includes a substance that prevents rust formation, includes a substance that is converted into a solid by light as a catalyst. This rust inhibitor is sprayed onto the welded portion (190), thereby forming a thin film while ensuring uniform application of the rust inhibitor.

[0093] When the surface to which the rust inhibitor has been applied is exposed to UV light, the reactive substances within the rust inhibitor are activated, causing the rust inhibitor to turn into a solid.

[0094] UV curing typically cures materials within seconds to minutes, improving productivity. UV curing requires relatively little energy for complete curing. Because UV lamp light rapidly activates specific materials, energy consumption is generally low. UV curing offers precise control, allowing the light to be directed only to the required area, allowing for precise curing of specific areas.

[0095] After forming the sealing portion (180), installation of the cap gasket (173) and the vent plate (160) and bending of the crimping portion (114) can be additionally performed.

[0096] FIG. 8 is a bottom view illustrating a state in which a rust-preventing portion (182) is formed on a fixed wing (138) of an exemplary negative electrode collector plate (130) according to the present invention. As illustrated in FIG. 8, the rust-preventing portion (182) may be formed on a welded portion (190) of the negative electrode collector plate (130) and on the negative electrode collector plate (130) that is in contact with the case (110). The fixed wing (138) of the negative electrode collector plate (130) that is in contact with the case (110) may extend in an arc shape along the curvature of the case (110) that is formed in a cylindrical shape. The fixed wing (138) is provided in plurality, and a welded portion (190) is located at the center of the fixed wing (138). The soundproofing part (182) can be applied in a shape that covers the welding part (190) and the fixed wings (138) on both sides of the welding part (190).

[0097] Fig. 9 is a bottom view illustrating a state in which a rust-preventing portion (184) is formed on the fixed wing (138) and the beading portion (113) of an exemplary negative electrode collector plate (130) according to the present invention. As illustrated in Fig. 9, the rust-preventing portion (184) may be formed around the entrance of the case (110) in which the negative electrode collector plate (130) is installed in contact. The rust-preventing portion (184) may be applied to the surfaces of the fixed wing (138) and the beading portion (113) of the case (110) and may be installed in a ring shape.

[0098] Fig. 10 is a bottom view illustrating a state in which an anti-rust coating portion (185) is formed on the entire surface of an exemplary negative electrode collector plate (130) according to the present invention. As illustrated in Fig. 10, the anti-rust portion (185) may be formed on the body portion (132), the extension portion (134), and the wing portion (136). The anti-rust portion (185) may be formed on the entire lower surface of the negative electrode collector plate (130). When the anti-rust coating portion (185) is formed on the entire lower surface of the negative electrode collector plate (130), corrosion can be prevented more effectively and durability can be improved compared to when the anti-rust coating is applied only to the welded portion. The upper surface of the negative electrode collector plate (130) is in contact with the electrode assembly (120), and the lower surface of the negative electrode collector plate (130) is installed facing the vent plate (160).

[0099] By applying an anti-rust coating to the entire lower surface of the negative current collector plate (130), corrosion protection can be provided not only at the welded area but also across the entire lower surface of the negative current collector plate (130). Accordingly, the negative current collector plate (130) can significantly reduce the possibility of corrosion due to contact with the electrolyte. In addition, since an anti-rust protective layer is formed across the entire lower surface of the negative current collector plate (130), the durability of the negative current collector plate (130) is improved, and battery performance can be maintained stably for a long period of time. In addition, compared to a case where an anti-rust coating is applied to only a portion of the negative current collector plate (130), when an anti-rust coating is applied to the entire lower surface of the negative current collector plate (130), the electrical and chemical properties of the electrode can be maintained more uniformly. In addition, the task of applying an anti-rust coating only to the welded area of ​​the negative current collector plate (130) may require precise process control and may increase the complexity of the process. However, if an anti-rust coating is applied to the entire lower surface of the negative electrode collector (130), the manufacturing process can be simplified compared to when an anti-rust coating is applied to only a portion of the negative electrode collector (130).

[0100] In addition, a rust-proofing portion (185) may be formed not only on the lower surface of the negative electrode collector (130) but also on the entire upper and lower surfaces of the negative electrode collector (130) except for the area where the electrode assembly (120) and the negative electrode collector (130) are connected.

[0101] Fig. 11 is a bottom view illustrating a state in which a rust-preventive coating portion (186) is formed in the center of an exemplary fixed wing (138) according to the present invention. As illustrated in Fig. 11, the rust-preventive portion (186) may be formed on the fixed wing (138) facing the wing body (137). The widthwise length of the wing body (137) and the widthwise length in which the rust-preventive portion (186) is formed may be the same. The rust-preventive portion (186) may be formed in a shape that covers the welded portion (190) formed on the fixed wing (138). The area where the negative electrode collector (130) and the case (110) are welded is an important point where electrical connection is made, and by applying an intensive rust-preventive coating to this area, connection failure or performance degradation due to corrosion can be effectively prevented. In addition, by applying the coating only to the necessary portion where the welded portion (190) is formed, rather than the entire surface of the negative electrode collector plate (130), the anti-rust coating material can be saved, and the manufacturing cost can be reduced. In addition, the anti-rust coating can be applied to cover the welded portion (190) of the fixed wing (138), and the anti-rust coating can be omitted from other portions of the negative electrode collector plate (130). Since the anti-rust coating is formed only on the essential portions of the negative electrode collector plate (130), other portions of the negative electrode collector plate (130) can be protected from the potential increase in electrical resistance caused by the anti-rust coating.

[0102] FIG. 12 is a bottom view illustrating a state in which an anti-rust coating portion (185) is formed at the center of an exemplary fixed wing (138) according to the present invention and at the inlet of the case (110). As illustrated in FIG. 12, the anti-rust portion (187) includes a first coating member (187a) and a second coating member (187b). The first coating member (187a) can be modified in various ways within the technical concept of applying an anti-rust coating to the fixed wing (138) facing the wing body (137). The second coating member (187b) can be modified in various ways within the technical concept of applying an anti-rust coating around the inlet of the case (110) where the fixed wing (138) is not positioned. The first coating member (187a) and the second coating member (187b) can be positioned on the same circular arc based on the center of the negative electrode current collector (130). The first coating member (187a) forms a first coating member (187a) that is a rust-preventing coating in a width direction equal to the width direction length of the wing body (137). The fixed wings (138) located on both sides of the first coating member (187a) may not be provided with an anti-rust coating.

[0103] The inlet portion of the case (110) located on both sides of the fixed wing (138) may be a beading portion (113) formed in the case (110). Since the negative electrode collector plate (130) is welded to the beading portion (113) protruding inwardly of the case (110), the negative electrode collector plate (130) can be fixed to the case (110).

[0104] The second coating member (187b) may be formed at the entrance of the case (110) located on both sides of the fixed wing (138). By forming the anti-corrosion portion (187) around the essential anti-corrosion portion of the negative electrode collector (130) and the entrance of the case (110), corrosion that may occur inside the secondary battery (100) can be effectively prevented.

[0105] In addition, by forming a rust-proof part (187) around the entrance of the case (110), leakage of electrolyte or intrusion of external substances can be prevented, thereby improving the safety of the secondary battery (100).

[0106] The electrode assembly is described in more detail below.

[0107] In some examples, a compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) may be used as the cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof may be used.

[0108] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0109] As an example, a compound represented by any one of the following chemical formulas may be used.

[0110] Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 dG e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0111] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0112] A positive electrode for a lithium secondary battery may include a current collector (e.g., a first substrate) and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0113] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0114] Aluminum may be used as the current collector, but is not limited thereto.

[0115] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0116] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0117] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-based alloy, or a combination thereof.

[0118] The above silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0119] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0120] A negative electrode for a lithium secondary battery may include a current collector (e.g., a second substrate) and a negative electrode active material layer formed on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0121] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0122] The above binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included.

[0123] The current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0124] An electrolyte for a lithium secondary battery may include a non-aqueous organic solvent and a lithium salt.

[0125] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0126] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof, and may be used alone or in combination of two or more thereof.

[0127] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0128] As described above, a lithium secondary battery may have a separator between the positive and negative electrodes. Such a separator may be a multilayer film of polyethylene, polypropylene, polyvinylidene fluoride, or two or more layers thereof.

[0129] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof, positioned on one or both sides of the porous substrate.

[0130] The above organic material may include a polyvinylidene fluoride-based antibody or a (meth)acrylic polymer.

[0131] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from, but not limited to, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0132] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0133] The battery according to the above-described embodiment can be used to manufacture a battery pack.

[0134] Figures 13a and 13b are perspective views illustrating a battery pack including an exemplary secondary battery according to the present invention. Referring to Figures 13a and 13b, the battery pack (300) may include a plurality of battery modules (200) and a housing (310) for accommodating the plurality of battery modules (200). For example, the housing (310) may include first and second housings (311, 312) that are coupled in a direction facing each other with the plurality of battery modules (200) interposed therebetween. The plurality of battery modules (210) may be electrically connected to each other using a bus bar (251), and the plurality of battery modules (200) may be electrically connected to each other in a series / parallel or series-parallel hybrid manner to obtain a required electrical output. In the drawings, for convenience of illustration, components such as a bus bar, a cooling unit, and an external terminal for electrically connecting battery cells are omitted. In some examples, the battery pack (300) may be mounted on a vehicle. A vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. A vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0135] Figures 14a and 14b are perspective and side views illustrating an automobile including an exemplary battery pack according to the present invention. In Figure 14a, the battery pack (300) may include a battery pack cover (311) (which may correspond to the first housing) which is a part of a vehicle underbody (410) and a pack frame (312) (which may correspond to the second housing) which is disposed at a lower portion of the vehicle underbody (410). The battery pack cover (311) and the pack frame (312) may be formed integrally with the vehicle floor (420). The vehicle underbody (410) separates the interior and exterior of the vehicle, and the pack frame (312) may be disposed at the exterior of the vehicle.

[0136] As illustrated in FIG. 14b, the vehicle (500) may be formed by combining additional components, such as a hood (510) at the front of the vehicle and fenders (520) positioned at the front and rear of the vehicle, respectively, with the vehicle body (400). The vehicle (500) includes a battery pack (300) including a battery pack cover (311) and a pack frame (312), and the battery pack (300) may be combined with the vehicle body component (400).

[0137] Although the present invention has been described above with reference to 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 idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. An electrode assembly comprising a first electrode plate, a second electrode plate, and a separator; A case in which the electrode assembly is accommodated inside; a cathode current collector fixed to the case by welding and electrically connected to the electrode assembly; and A secondary battery including a rust-preventing member applied to a connecting portion of the negative electrode current collector welded to the case to prevent rust.

2. In paragraph 1, A secondary battery characterized in that the above-mentioned anti-corrosion part uses at least one of polymer series PI, PAI, silicone resin and epoxy resin.

3. In paragraph 1, A secondary battery characterized in that the above-mentioned rust-proof part is formed at a welded portion of the negative electrode collector plate.

4. In paragraph 1, A secondary battery characterized in that the above-mentioned rust-proof part is formed on the welded portion of the negative electrode collector plate and the negative electrode collector plate in contact with the case.

5. In paragraph 1, A secondary battery characterized in that the above-mentioned soundproofing part is formed around the entrance of the case in which the negative electrode collector is installed in contact with it.

6. In paragraph 1, A secondary battery characterized in that the number of welds between the negative electrode collector plate and the case is 3 to 6.

7. In paragraph 6, A secondary battery characterized in that the number of coatings on the above-mentioned anti-corrosion portion is the same as the number of weldings.

8. In paragraph 1, A secondary battery characterized in that the above-mentioned rust-preventing part applies a rust-preventing agent to the negative electrode current collector and then UV-cures it.

9. In paragraph 8, A secondary battery characterized in that the time required for the above UV curing is 5 to 12 seconds.

10. In paragraph 8, A secondary battery characterized in that the temperature at which the above UV curing is performed is 100°C to 170°C.

11. In paragraph 8, A secondary battery characterized in that the coating thickness of the above-mentioned anti-corrosion part is 3 to 10 um.

12. In paragraph 8, A secondary battery characterized in that the above-mentioned anti-rust solution is applied to the negative electrode current collector by spraying.

13. An electrode assembly comprising a first electrode plate, a second electrode plate, and a separator; A case in which the electrode assembly is accommodated inside; A cathode collector plate which is fixed to the case by welding and electrically connected to the electrode assembly; An anti-rust portion applied to the connecting portion of the negative electrode collector plate welded to the case to prevent rust; A vent plate shielding the open inlet of the above case; and A secondary battery including a cap gasket installed in a shape that surrounds the outer periphery of the vent plate and blocks electrical connection between the negative electrode collector plate and the case and the vent plate.

14. In paragraph 13, The above negative electrode collector plate is a body part installed in contact with the second electrode plate; An extension portion extending to the outside of the body portion and installed in contact with the second electrode plate together with the body portion; and A secondary battery including a wing portion extending outwardly from the body portion in a state spaced apart from the extension portion and fixed to the case by welding.

15. In paragraph 14, A secondary battery characterized in that the above-mentioned soundproofing part is formed in the body part, the extension part, and the wing part.

16. In paragraph 14, The above wing portion includes a wing body extending from the body portion; and A secondary battery including a fixed wing extending in an arc shape from an end of the wing body and fixed to the case by welding.

17. In paragraph 16, A secondary battery characterized in that the above-mentioned soundproofing part is formed at a welded portion of the fixed wing or the entire fixed wing.

18. In paragraph 16, A secondary battery characterized in that the above-mentioned soundproofing part is formed on the fixed wing facing the wing body.

19. In paragraph 16, The above-mentioned anti-rust portion comprises a first coating member in which an anti-rust coating is applied to the fixed wing facing the wing body; and A secondary battery including a second coating member having an anti-rust coating formed around the inlet of the case where the fixed wing is not located.

20. In paragraph 13, A secondary battery characterized in that the above-mentioned rust-proofing part uses at least one of polyvinylidene fluoride (PVDF), epoxy resin, polyurethane, ceramic coating, and polytetrafluoroethylene (PTFE).

Images