Secondary battery

Abstract

The present invention relates to a secondary battery capable of preventing lifting by reinforcing the strength of an edge region of a terminal plate of a terminal. As an example of the present invention, disclosed is a secondary battery including: an electrode assembly including a first electrode, a separator, and a second electrode; a cylindrical case that accommodates the electrode assembly and has an open lower end; a terminal electrically connected to the first electrode of the electrode assembly and exposed to the outside of the case through the upper portion of the case; and a cap plate sealing the lower end of the case, wherein the terminal includes a protrusion protruding from the outside of the case toward the upper portion of the case.

Description

secondary battery

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

[0002] Secondary batteries are power storage systems that offer superior energy density by converting electrical energy into chemical energy and storing it. Compared to non-rechargeable primary batteries, secondary batteries are rechargeable and are widely used in IT devices such as smartphones, cellphones, laptops, and tablet PCs. Recently, interest in electric vehicles has grown to prevent environmental pollution, leading to the adoption of high-capacity secondary batteries in electric vehicles. These secondary batteries require high density, high output, and stability.

[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 can prevent lifting by reinforcing the strength of the edge area of ​​the terminal plate of the terminal.

[0005] In addition, the present invention can reduce the loss of internal space by applying steps and forgings to correspond to the shape of the terminal at the center of the 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] According to one embodiment of the present invention for solving the above technical problem, a secondary battery includes an electrode assembly having a first electrode, a separator, and a second electrode, a cylindrical case in which the electrode assembly is accommodated and has an open bottom, a terminal electrically connected to the first electrode of the electrode assembly, penetrating the upper portion of the case and exposed to the outside of the case, and a cap plate sealing the lower portion of the case, wherein the terminal may have a protrusion protruding from the outside of the case toward the upper portion of the case.

[0008] The terminal may be arranged on the outer side of the upper portion of the case and may include a terminal plate having a terminal hole in the center, and a fastening member that penetrates the case and the terminal plate on the inner side of the upper portion and is coupled to the terminal plate.

[0009] The above protrusion may protrude downward along the edge of the lower surface of the terminal plate.

[0010] The thickness of the above protrusion may be thicker than the thickness of other areas of the terminal plate and less than 2.2 times.

[0011] The terminal plate may include a mounting groove formed concavely from the upper surface to the lower surface in the peripheral area of ​​the terminal hole.

[0012] The case includes a flat, circular upper portion and a cylindrical body extending downward from an edge of the upper portion, the upper portion including an upper center portion located at the center; and an upper edge portion located on the outside of the upper center portion, wherein the upper center portion can protrude outward compared to the upper edge portion.

[0013] The upper portion of the case may further include an upper connecting portion connecting the upper center portion and the upper edge portion.

[0014] The outer diameter of the upper center portion may be smaller than the outer diameter of the protrusion.

[0015] The above protrusion may be located on the upper portion of the upper edge portion.

[0016] An insulating member may further be included between the terminal and the case.

[0017] The insulating member may include an outer insulating member interposed between the upper portion of the case and the terminal plate, and between the terminal hole of the case and the fastening member, and an inner insulating member positioned on the lower portion of the upper portion of the case and in contact with the outer insulating member.

[0018] The outer insulating member may have a region located on the lower side of the protrusion that is stepped from another region located on the lower side of the terminal plate, and may have a thickness thinner than the other region.

[0019] The inner insulating member may include an outer protruding region that is convex downwardly along an edge of the lower surface, and a central protruding region that is protruded downwardly along an area adjacent to the center of the lower surface.

[0020] The above central protrusion region may be located on the lower side of the upper connecting portion and the upper edge portion adjacent to the upper connecting portion.

[0021] The upper central portion includes a central region adjacent to the terminal hole and an outer region located outside the central region, and the central region may be thinner than the outer region and may be concave in an upward direction.

[0022] The above-mentioned fastening member may include a cylindrical main body, a head portion located at one end of the main body and located inside the case, and a deformation portion located at the other end of the main body and plastically deformed to be coupled with the terminal plate.

[0023] The inner insulating member may include a first region interposed between the upper surface of the head portion and the central region of the upper center portion, a second region located outside the first region and having a step from the first region, and a third region connecting the first region and the second region and covering the side of the head portion.

[0024] The above first region may protrude in the upper direction of the case compared to the above second region.

[0025] The inner insulating member may have a uniform thickness.

[0026] According to the present invention, a secondary battery can be provided that can prevent lifting by reinforcing the strength of the edge area of ​​the terminal plate of the terminal.

[0027] In addition, according to the present invention, a secondary battery can be provided that can reduce loss of internal space by applying steps and forgings to correspond to the shape of a terminal at the center of a case.

[0028] 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.

[0029] 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.

[0030] Figure 1 is a perspective view illustrating a secondary battery according to the present invention.

[0031] Figure 2 is an example of a cross-sectional view of the secondary battery illustrated in Figure 1.

[0032] Figure 3 is an enlarged view of part A of Figure 2.

[0033] Figure 4 is a cross-sectional view of a secondary battery according to the present invention.

[0034] Figure 5 is an enlarged view of part B of Figure 4.

[0035] Figure 6 is a cross-sectional view of a secondary battery according to the present invention.

[0036] Figure 7 is an enlarged view of part C of Figure 6.

[0037] 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.

[0038] 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.

[0039] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0040] 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.

[0041] 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.

[0042] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0043] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] FIG. 1 is a perspective view illustrating a secondary battery according to the present invention, and FIG. 2 is a cross-sectional view of the secondary battery illustrated in FIG. 1.

[0048] As illustrated in FIGS. 1 and 2, the secondary battery (100) may include an electrode assembly (110), a case (120) that accommodates the electrode assembly (110) and an electrolyte therein, a terminal (150) coupled to a terminal hole provided at one end of the case (120), for example, an upper end, and a cap plate (160) that seals the other end of the case (110), for example, a lower end. The secondary battery (100) may further include a first collector plate (130) that electrically connects a first electrode (111) of the electrode assembly (110) and the terminal (150), and a second collector plate (140) that electrically connects a second electrode (112) of the electrode assembly (110) and the case (120).

[0049] The electrode assembly (110) may include a separator (113), a first electrode (111) and a second electrode (112) positioned with the separator (113) between them, and may be wound in a jelly-roll shape.

[0050] A first electrode (111) includes a first substrate and a first active material layer positioned on the first substrate. A first electrode tab may extend outward from a first non-conductive portion of the first substrate where the first active material layer is not positioned, and the first electrode tab may be electrically connected to a terminal (150) via a first current collector (130). A second electrode (112) includes a second substrate and a second active material layer positioned on the second substrate. A second electrode tab may extend outward from a second non-conductive portion of the second substrate where the second active material layer is not positioned, and the second electrode tab may be electrically connected to a case (120) via a second current collector (140). The first electrode tab and the second electrode tab may be positioned in opposite directions in the electrode assembly (110). The first electrode (111) may function as a positive electrode. In this case, the first substrate may be composed of, for example, aluminum foil, and the first active material layer may include, for example, a transition metal oxide. The second electrode (112) may function as a negative electrode. In this case, the second substrate may be composed of, for example, copper foil or nickel foil, and the second active material layer may include, for example, graphite. The separator (113) functions to prevent short circuiting between the first electrode (111) and the second electrode (112) while allowing the movement of lithium ions. The separator (113) may be composed of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, etc. The case (120) accommodates the electrode assembly (110) and the electrolyte, and together with the terminal (150) and the cap assembly (160), constitutes the outer appearance of the secondary battery (100). The case (120) may include a body portion (121) having a roughly cylindrical shape and an upper portion (122) connected to one side of the body portion (121). A beading portion (123) deformed toward the inside may be positioned in the body portion (121), and a crimping portion (124) bent toward the inside may be positioned at an end on the opening side of the body portion (121). A terminal hole (122a) penetrating through the center may be provided in the upper portion (122).The upper part (122) can be coupled by inserting a terminal (150) into the terminal hole. An insulating member (125, 127) for sealing and electrical insulation can be further interposed between the terminal hole and the terminal (150). The beading portion (123) can suppress movement of the electrode assembly (110) inside the case (120) and facilitate the settling of the cap gasket (127) and the cap plate (160). The crimping portion (124) can firmly fix the cap plate (160) by pressing the edge of the cap plate (160) through the cap gasket (127). The case (123) can be made of, for example, nickel-plated iron.

[0051] The first collector plate (130) may have one surface that contacts and is coupled to the first electrode tab of the electrode assembly (110), and the other surface that contacts and is coupled to the terminal (150). The first collector plate (130) may be welded to the first electrode tab of the electrode assembly (110) and electrically connected. The first collector plate (130) may be welded and electrically connected while the other surface is in contact with the terminal (150).

[0052] The second collector plate (140) may have a central portion (141) that contacts and is coupled with the second electrode tab of the electrode assembly (110), and an edge portion (142) that contacts and is coupled with the body portion (121) of the case (120). The second collector plate (140) may be electrically connected by having the central portion (141) welded to the second electrode tab of the electrode assembly (110). The second collector plate (140) may be electrically connected by having the edge portion (142) welded in a state in which it contacts the beading portion (123) of the case (120).

[0053] The terminal (150) may include a terminal plate (151) positioned on the outside of the case (120), and a fastening member (152) that penetrates the terminal plate (151) and the case (120) and is connected thereto. The terminal plate (151) may have a terminal hole (151a) penetrating through its center. The fastening member (152) may be fixed by pressing the terminal plate (151) through the terminal hole (122a) of the upper portion (122) and the terminal hole (151a) of the terminal plate (151) from the inside of the case (120). An insulating member (125, 126) for electrical insulation may be interposed between the terminal (150) and the case (120). The fastening member (152) may further have a terminal groove (153) extending inward from the center. The terminal (150) can be externally welded to the first collector plate (130) through the terminal groove (153). The terminal (150) can be electrically connected to the first electrode (111) of the electrode assembly (110) through the first collector plate (130). The terminal (150) can have a different polarity from the case (120). The cap plate (160) can be fixed to the inside of the crimping portion (124) through the cap gasket (127) to seal the case (120). The cap plate (160) can include a safety vent (165) that is thinner than other areas due to the notch. When gas is generated due to overcharging or abnormal operation of the secondary battery (100), the safety vent (165) provided in the cap plate (160) can be cut along the notch. The cut safety vent (165) can prevent an explosion of the secondary battery (100) by releasing gas to the outside.

[0054] However, the present invention is not limited thereto, and the case may be configured in various shapes, such as circular or pouch-shaped. In addition, the case may be configured of a metal such as aluminum, aluminum alloy, nickel-plated steel, or a laminate film or plastic forming a pouch.

[0055] Fig. 3 is an enlarged view of part A of Fig. 2. Hereinafter, with reference to Figs. 1 to 3, the combination and structure of the terminal (150) and the case (120) will be described.

[0056] First, the upper portion (122) of the case (120) may have a circular plate shape. In addition, the body portion (121) may have a cylindrical shape extending downward from the edge of the upper portion (122). The upper portion (122) may include an upper center portion (1221) located at the center, and an upper edge portion (1222) located on the outer side of the upper center portion (1221) in a plan view. The upper center portion (1221) may protrude outwardly away from the electrode assembly (110) compared to the upper edge portion (1222). A step may be provided between the upper center portion (1221) and the upper edge portion (1222). The upper portion (1222) may further include an upper connecting portion (1223) connecting the upper center portion (1221) and the upper edge portion (1222). The upper portion (122) may have a terminal hole (122a) penetrating approximately the center of the upper center portion (1221). A terminal (150) can be inserted and connected into the terminal hole (122a) of the upper portion (122). The upper portion (122) has a shape in which the peripheral area where the terminal hole (122a) is formed protrudes upward.

[0057] Here, the upper center portion (1221) can be formed by pressing from the inside to the outside of the flat upper portion (122) by deep drawing. In addition, the upper center portion (1221) can have a circular or polygonal planar shape. The upper center portion (1221) can have a shape corresponding to the terminal plate (151) of the terminal (150) on the planar surface. Since the upper center portion (1221) protrudes from the upper edge portion (1222), a space for installing the case (120) in which the terminal (150) is to be installed can be secured. Accordingly, the distance between the upper portion (122) and the first collector plate (130) can be reduced. Accordingly, the loss of the internal space of the case (120) can be minimized.

[0058] The terminal (150) may include a terminal plate (151) and a fastening member (152). The terminal plate (151) and the fastening member (152) may be made of the same material as the first current collector plate (130). For example, the terminal plate (151) and the fastening member (152) may be made of aluminum or an aluminum alloy.

[0059] A terminal plate (151) is arranged on the outer side of the upper portion (122) of the case (120). The terminal plate (151) is coupled with a fastening member (152) that passes through a terminal hole (122a) of the upper portion (122) and is fixed to the outer side of the upper portion (122). The terminal plate (151) may have a terminal hole (151a) provided at the center for inserting the fastening member (152). A mounting groove (1512) for mounting the fastening member (152) may be formed in a peripheral area of ​​the terminal hole (151a). The mounting groove (1512) may be formed concavely from the upper surface of the terminal plate (151). In addition, the mounting groove (1512) may have a larger diameter than the terminal hole (151a). After the terminal plate (151) and the fastening member (152) are combined, the upper surface of the terminal plate (151) and the upper surface of the fastening member (152) can be positioned on the same plane.

[0060] The terminal plate (151) may further include a protrusion (1511) protruding downward from the edge of the lower surface. The protrusion (1511) may protrude in a ring shape on the lower surface of the terminal plate (151) in a planar manner. As another example, a plurality of protrusions (1511) may protrude from the lower surface of the terminal plate (151) so as to be spaced apart from each other on the plane. Of course, a plurality of protrusions (1511) may protrude downward from the lower surface of the terminal plate (151). Here, the thickness (H1) of the region where the protrusion (1511) is located may be greater than the thickness (H2) of other regions of the terminal plate (151) and less than 2.2 times. The protrusion (1511) may be located on the outer side of the upper center portion (1221) and the upper connection portion (1223) on the plane. The protrusion (1511) may be located on the upper edge portion (1222). That is, the protrusion (1511) does not overlap with the upper center portion (1221) and the upper connection portion (1223) on a plane. Here, the outer diameter of the terminal plate (151) may be larger than the outer diameter of the upper center portion (1221) and the outer diameter of the upper connection portion (1223). In addition, the outer diameter of the protrusion (1511) may be the same as the outer diameter of the terminal plate (151). In addition, the inner diameter of the protrusion (1511) may be larger than the outer diameter of the upper center portion (1221) and the outer diameter of the upper connection portion (1223). For example, the inner diameter of the protrusion (1511) may be 43% to 90% of the outer diameter of the terminal plate (151). In addition, the outer diameter of the upper center portion (1221) may be 37% to 80% of the outer diameter of the terminal plate (151).

[0061] The terminal plate (151) is a thin plate shape, but since it has a protrusion (1511), rigidity can be secured due to an increase in the thickness of the edge region. In addition, since the protrusion (1511) is located on the outer side of the upper center (1221) and the upper connecting portion (1223) on a plane, the bonding force between the case (120) and the terminal plate (151) can be increased. In addition, since the terminal plate (151) has the protrusion (1511), after the fastening member (152) is riveted onto the terminal plate (151), the edge region of the terminal plate (151) can be prevented from being lifted off from the case (120).

[0062] The fastening member (152) has a roughly cylindrical shape and may be referred to as a rivet terminal. The fastening member (152) may be provided with a terminal groove (153) located approximately in the center from the upper surface to the lower surface. The fastening member (152) may be riveted to the upper portion (122) of the case (120) and the terminal plate (151).

[0063] The fastening member (152) may include a cylindrical body portion (1521), a head portion (1522) provided at one end of the body portion (1521), and a deformation portion (1523) provided at the other end of the body portion (1521). The fastening member (152) may be inserted by penetrating the terminal hole (122a) from the inside to the outside of the case (120). The head portion (1522) of the fastening member (152) may be located at the inside of the case (120). The deformation portion (1523), which is an end portion of the body portion (1521) that penetrates the terminal hole (122a) of the case (120) and the terminal hole (151a) of the terminal plate (151), may be plastically deformed to be coupled to the terminal plate (151). At this time, the deformation portion (1523) can be pressed outwardly on a plane to fill the mounting groove (1512) of the terminal plate (151). Since the plastic deformation of the deformation portion (1523) of the fastening member (152) occurs from the outside, the processed area can be visually inspected from the outside, thereby improving the reliability of the product.

[0064] The terminal plate (151) and the fastening member (152) of the above-described structure can be insulated from the upper part (122) of the case (120) by the outer insulating member (125) and the inner insulating member (126).

[0065] The outer insulating member (125) may be interposed between the upper portion (122) of the case (120) and the terminal plate (151), and between the terminal hole (122a) of the case (120) and the fastening member (152). The outer insulating member (125) may cover the terminal hole (122a) of the case (120) and extend along the upper portion of the case (120). In addition, the outer insulating member (125) may have a shape corresponding to the stepped shape of the upper portion (122) of the case (120) and the shape of the protrusion (1511) of the terminal plate (151). The outer insulating member (125) may have a thickness of one end region located below the protrusion (1511) of the terminal plate (151) thinner than other regions. That is, the outer insulating member (125) may have a step difference between one end region and other regions. The upper surface of the above outer insulating member (125) may be positioned lower than the upper surface of another area.

[0066] Additionally, the outer insulating member (125) may also be interposed between the inner surface of the upper portion (122) and the head portion (1522) of the fastening member (152). The outer insulating member (125) may be interposed between the inner surface of the upper portion (122) and the head portion (1522) of the fastening member (152) at the other end, and may be in contact with the inner insulating member (126).

[0067] The inner insulating member (126) has a roughly circular plate shape and can be positioned on the lower side of the upper part (122) of the case (120). The inner insulating member (126) is provided with a terminal hole penetrating the center, and the fastening member (152) can be coupled to the upper part (122) of the case (120) and the terminal plate (151) by penetrating the terminal hole of the inner insulating member (126). The inner insulating member (126) can have a central region adjacent to the terminal hole interposed between the upper part (122) and the head portion (1522) of the fastening member (152).

[0068] Additionally, the inner insulating member (126) may be provided with downwardly convex protruding regions (126a, 126b). The inner insulating member (126) may have a thicker protruding region (126a, 126b) than other regions. Here, the protruding regions (126a, 126b) may include an outer protruding region (126b) that protrudes downward along an edge of the lower surface of the inner insulating member (126) and a central protruding region (126a) that protrudes downward along an area adjacent to the center of the lower surface. The protruding regions (126a, 126b) may have a circular ring shape in plan view. The central protruding region (126a) may be located below the upper connecting portion (1223). In more detail, the central protrusion region (126a) may be located on the lower side of the upper connecting portion (1223) and the upper edge portion (1222) adjacent to the upper connecting portion (1223). The central protrusion region (126a) may be spaced apart from the head portion (1522) of the fastening member (152). The central protrusion region (126a) may partially overlap with the protrusion portion (1511) of the flat terminal plate (151).

[0069] Since the inner insulating member (126) can secure some space between the upper surface of the electrode assembly (110) and the protruding area (126a), the space can be secured and shaking can be prevented when the electrode assembly (110) expands and contracts during charging / discharging.

[0070] The inner insulating member (126) and the outer insulating member (125) can be fixed to the case (120) by a terminal (150).

[0071] Additionally, a compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) may be used as the positive electrode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0072] 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.

[0073] As an example, a compound represented by any one of the following chemical formulas may be used: 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 d G 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); Lia 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).

[0074] 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.

[0075] A positive electrode for a lithium secondary battery may include a current collector 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.

[0076] 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.

[0077] Al may be used as the above current collector, but is not limited thereto.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] A negative electrode for a lithium secondary battery includes a current collector and a negative electrode active material layer positioned 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.

[0084] 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.

[0085] 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.

[0086] The negative electrode 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.

[0087] An electrolyte for a lithium secondary battery contains a non-aqueous organic solvent and a lithium salt.

[0088] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0089] 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.

[0090] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0091] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Such separators may be polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film comprising two or more layers of these.

[0092] 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.

[0093] The above organic material may include a polyvinylidene fluoride-based antibody or a (meth)acrylic polymer.

[0094] 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.

[0095] 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.

[0096]

[0097] FIG. 4 is a cross-sectional view of a secondary battery (200) according to the present invention, and FIG. 5 is an enlarged view showing part B of FIG. 4. The secondary battery (200) may have a configuration similar to that of the secondary battery (100) previously described. The secondary battery (200) may include an electrode assembly (110), a case (220), a first current collecting plate (130), a second current collecting plate (140), a terminal (150), and a cap plate (160). Here, the secondary battery (200) may have electrode assembly (110), first current collecting plate (130), second current collecting plate (140), terminal (150), and cap plate (160) similar to those of the secondary battery (100). Hereinafter, the case (220) of the secondary battery (200), which is different from that of the secondary battery (100), will be mainly described.

[0098] First, the upper portion (222) of the case (220) may have a circular plate shape. The upper portion (222) may include an upper center portion (2221) located at the center and an upper edge portion (2222) located outside the upper center portion (2221) in a plan view. The upper center portion (2221) may protrude outwardly away from the electrode assembly (110) compared to the upper edge portion (2222). A step may be provided between the upper center portion (2221) and the upper edge portion (2222). The upper portion (222) may further include an upper connecting portion (2223) connecting the upper center portion (2221) and the upper edge portion (2222). The upper portion (222) may have a terminal hole (222a) penetrating approximately the center of the upper center portion (2221). A terminal (150) may be inserted into and coupled to the terminal hole (222a) of the upper portion (222). The upper part (222) has a shape in which the peripheral area where the terminal hole (222a) is formed protrudes upward in a convex manner.

[0099] Here, the upper central portion (2221) may be formed by pressing from the inside to the outside of the flat upper portion (222) by deep drawing. The upper central portion (2221) may include a central region (2221a) adjacent to the terminal hole (222a) and an outer region (2221b) located outside the central region (2221a) on a planar surface. Here, the central region (2221a) may be pressed further and thus may have a thinner thickness than the outer region (2221b). The upper surface of the central region (2221a) and the outer region (2221b) may be located on the same plane. The lower surface of the central region (2221a) may be more concave in the upper surface direction than the lower surface of the outer region (2221b). The lower surface of the central region (2221a) may have a step between the lower surface of the outer region (2221b). The thickness of the central region (2221a) may be 60% to 90% of the thickness of the outer region (2221b). The thickness of the outer region (2221b) may be similar to the thickness of the upper edge portion (2222) and the upper connecting portion (2223).

[0100] The head portion (1522) of the fastening member (152) may be positioned at the lower portion of the central region (2221a). That is, by making the thickness of the central region (2221a) where the head portion (1522) is positioned thinner in the upper central portion (1221), the space where the head portion (1522) is positioned can be more secured. Accordingly, the distance between the upper portion (122) of the case (120) and the first collector plate (130) can be further reduced. That is, the loss of the internal space of the case (120) can be further minimized.

[0101] The terminal plate (151) and the fastening member (152) can be insulated from the upper part (222) of the case (220) by the outer insulating member (225) and the inner insulating member (226).

[0102] The outer insulating member (225) may be similar to the outer insulating member (225) of the secondary battery (100).

[0103] The inner insulating member (226) has a roughly circular plate shape and can be positioned on the lower side of the upper part (222) of the case (220). The inner insulating member (226) is provided with a terminal hole penetrating the center, and the fastening member (152) can be coupled to the upper part (222) of the case (220) and the terminal plate (151) by penetrating the terminal hole of the inner insulating member (226). The inner insulating member (226) can include a first region (2261) adjacent to the terminal hole, and a second region (2262) positioned on the outer side of the first region (2261) in a planar manner. The first region (2261) can protrude toward the upper part (222) of the case (220) compared to the second region (2262). A step can be provided between the first region (2261) and the second region (2262). The inner insulating member (226) may include a third region (2263) connecting the first region (2261) and the second region (2262). The first region (2261) may be in close contact with the lower surface of the central region (2221a) of the upper central portion (2221) of the case (120). In addition, the second region (2262) may be located on the outer region (2221b) of the upper central portion (2221) of the case (220) and the lower side of the upper connecting portion (2223) and the upper edge portion (2222). The first region (2261) may be interposed between the head portion (1522) of the terminal (150) and the central region (2221a) of the upper central portion (2221). The third region (2263) may cover the side surface of the head portion (1522) of the terminal (150). That is, the inner insulating member (226) can be bent and extended along the upper and side surfaces of the head portion (1522). The inner insulating member (226) can have a constant thickness.

[0104]

[0105] Fig. 6 is a cross-sectional view of a secondary battery (300) according to the present invention, and Fig. 7 is an enlarged view showing part B of Fig. 6. The secondary battery (300) may have a configuration similar to that of the secondary battery (200) previously described. The secondary battery (300) may include an electrode assembly (110), a case (220), a first current collecting plate (130), a second current collecting plate (140), a terminal (350), and a cap plate (160). Here, the electrode assembly (110), the case (220), the first current collecting plate (130), the second current collecting plate (140), and the cap plate (160) of the secondary battery (300) may be similar to those of the secondary battery (100). Hereinafter, the terminal (350), which is different from that of the secondary battery (200), will be mainly described in the secondary battery (300).

[0106] The terminal (350) may include a terminal plate (351) and a fastening member (152). The terminal plate (351) and the fastening member (152) may be made of the same material as the first current collector plate (130). For example, the terminal plate (351) and the fastening member (152) may be made of aluminum or an aluminum alloy. The fastening member (152) may be similar to the fastening member (152) of the secondary battery (100).

[0107] The terminal plate (351) is arranged on the outer side of the upper part (122) of the case (120) in a flat plate shape. The terminal plate (351) is coupled with a fastening member (152) that passes through a terminal hole (122a) of the upper part (122) and is fixed to the outer side of the upper part (122). The terminal plate (351) may have a terminal hole (151a) provided at the center for inserting the fastening member (152). A mounting groove (1512) for mounting the fastening member (152) may be formed in a peripheral area of ​​the terminal hole (351a). The mounting groove (1512) may be formed concavely from the upper surface of the terminal plate (351). In addition, the mounting groove (1512) may have a larger diameter than the terminal hole (351a). After the terminal plate (351) and the fastening member (152) are combined, the upper surface of the terminal plate (351) and the upper surface of the fastening member (152) can be positioned on the same plane.

[0108] The terminal plate (351) may have a certain thickness except for the area where the mounting groove (1512) is located. The outer diameter of the terminal plate (351) may be similar to the outer diameter of the upper center portion (2221). An outer insulating member (225) may be interposed between the terminal plate (351) and the upper center portion (2221).

[0109] 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 having a first electrode, a separator, and a second electrode; A cylindrical case in which the electrode assembly is accommodated and has an open bottom; A terminal electrically connected to the first electrode of the electrode assembly, penetrating the upper part of the case and exposed to the outside of the case; and Includes a cap plate that seals the lower part of the case, The secondary battery has a terminal having a protrusion protruding from the outside of the case toward the upper side of the case.

2. In paragraph 1, The above terminal A terminal plate disposed on the outer side of the upper portion of the case and having a terminal hole in the center; and A secondary battery including a case on the inner side of the upper portion and a fastening member penetrating the terminal plate and coupled to the terminal plate.

3. In paragraph 2, The above-mentioned protrusion is a secondary battery that protrudes downward along the edge of the lower surface of the terminal plate.

4. In paragraph 3, A secondary battery in which the thickness of the above protrusion is thicker and less than 2.2 times than the thickness of other areas of the terminal plate.

5. In paragraph 2, A secondary battery in which the terminal plate includes a mounting groove formed concavely from the upper surface to the lower surface in the peripheral area of ​​the terminal hole.

6. In paragraph 3, The above case is The upper part is in the shape of a flat circular plate; and It includes a cylindrical body extending downward from the upper edge, The upper part is the upper center located in the center; and Includes an upper edge portion located outside the upper center portion, A secondary battery in which the upper central portion protrudes outward compared to the upper edge portion.

7. In paragraph 6, The upper part of the above case A secondary battery further comprising an upper connecting portion connecting between the upper central portion and the upper edge portion.

8. In paragraph 6, A secondary battery in which the outer diameter of the upper center portion is smaller than the outer diameter of the protrusion portion.

9. In paragraph 6, A secondary battery in which the above protrusion is located on the upper portion of the upper edge portion.

10. In paragraph 7, A secondary battery further comprising an insulating member interposed between the terminal and the case.

11. In paragraph 10, The above insulating material An outer insulating member interposed between the upper portion of the case and the terminal plate, and between the terminal hole of the case and the fastening member; and A secondary battery positioned at the lower side of the upper portion of the case and including an inner insulating member in contact with the outer insulating member.

12. In paragraph 11, The above outer insulating member is a secondary battery in which one region located on the lower side of the protrusion is stepped from another region located on the lower side of the terminal plate and has a thickness that is thinner than the other region.

13. In paragraph 11, A secondary battery in which the inner insulating member includes an outer protrusion region convex downwardly along an edge from the lower surface and a central protrusion region protruding downwardly along an area adjacent to the center of the lower surface.

14. In paragraph 13, The secondary battery wherein the central protrusion region is located on the lower side of the upper connecting portion and the upper edge portion adjacent to the upper connecting portion.

15. In paragraph 11, The upper center above a central area adjacent to the terminal hole; and Including an outer region located outside the above central region, A secondary battery in which the central region is thinner than the outer region and is concave in the upward direction.

16. In paragraph 15, The above fastening member Cylindrical body; A head portion located at one end of the main body portion and located inside the case; and A secondary battery including a deformable portion located at the other end of the main body and plastically deformed and coupled to the terminal plate.

17. In paragraph 16, The inner insulating member comprises a first region interposed between the upper surface of the head portion and the central region of the upper central portion; A second region located outside the first region and having a step from the first region; and A secondary battery comprising a third region connecting the first region and the second region and covering a side of the head portion.

18. In paragraph 17, The above first region is a secondary battery that protrudes in the upper direction of the case compared to the above second region.

19. In paragraph 17, A secondary battery wherein the inner insulating member has a uniform thickness.

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