Electrode assembly and secondary battery comprising same

Abstract

This electrode assembly comprises separator, a first electrode, and a second electrode. The first electrode and the second electrode are positioned with the separator interposed therebetween, and are wound together with the separator. At least one of the first electrode and the second electrode includes a main body and a substrate tab. The main body is composed of a base material and a mixed material layer. The substrate tab is positioned on one side of the main body at a distance from the mixed material layer, and is bent from the main body. The substrate tab includes: a plurality of first extension tabs having a trapezoidal shape, the height of which gradually changes along the longitudinal direction of the main body; and a plurality of second extension tabs having the same height and having a parallelogram shape.

Description

Electrode assembly and secondary battery having the same

[0001] The present disclosure relates to a secondary battery, and more particularly, to a secondary battery including a roll-type electrode assembly.

[0002] Rechargeable secondary batteries are used in a variety of applications, including powering small electronic devices such as mobile phones and laptops, and powering motors in vehicles such as electric and hybrid vehicles. A secondary battery essentially consists of an electrode assembly and a case that houses and seals the electrode assembly. Depending on their external shape, they can be categorized into cylindrical, prismatic, and pouch-shaped batteries.

[0003] An electrode constituting an electrode assembly may include a body composed of a substrate and a composite layer, and a plurality of extension tabs positioned on one side of the body. The plurality of extension tabs may be processed by laser cutting, and may be bent toward the winding center of the electrode assembly so as to overlap with extension tabs positioned inside thereof. The plurality of bent extension tabs may be fixed to a current collector plate by a method such as laser welding.

[0004] The present disclosure provides an electrode assembly capable of improving finishing quality by reducing the occurrence of defects in the process of bending multiple expansion tabs, and a secondary battery having the same.

[0005] An electrode assembly according to one embodiment includes a separator, a first electrode, and a second electrode. The first electrode and the second electrode are positioned with the separator therebetween and are wound together with the separator. At least one of the first electrode and the second electrode includes a body and a plurality of extension tabs. The body is composed of a substrate and a composite layer, and includes a leading end and a terminal end. The plurality of extension tabs are positioned on one side of the body at a distance from the composite layer along a width direction of the body, are positioned closer to the terminal end than to the leading end along a length direction of the body, and are bent from the body. The plurality of extension tabs are defined by a plurality of cutting lines inclined at a constant angle with respect to the length direction of the body and the width direction of the body.

[0006] The plurality of extension tabs may have a constant width and may be inclined toward the longitudinal end as they move away from the composite layer. The total length of the plurality of extension tabs along the longitudinal direction of the body may be greater than half the length of the body. The body may include an insulating layer positioned in contact with the composite layer, and the plurality of extension tabs may be positioned in contact with the insulating layer.

[0007] According to another embodiment, an electrode assembly includes a separator, a first electrode, and a second electrode. The first electrode and the second electrode are positioned with the separator therebetween and are wound together with the separator. At least one of the first electrode and the second electrode includes a body and a substrate tab. The body is composed of the substrate and a composite layer. The substrate tab is positioned on one side of the body at a distance from the composite layer and is bent from the body. The substrate tab includes a plurality of first extension tabs having a trapezoidal shape whose height gradually changes along the longitudinal direction of the body, and a plurality of second extension tabs having a parallelogram shape and having the same height.

[0008] The substrate tabs may be divided into a leading region, a middle region, and a terminal region. Non-extended tabs may be located in the leading region. A plurality of first extended tabs may be located in the middle region, and a plurality of second extended tabs may be located in the terminal region. The height of the plurality of first extended tabs may increase as they move away from the leading region.

[0009] The plurality of second extension tabs may have a constant width and may be defined by a plurality of cut lines inclined at a constant angle with respect to the longitudinal direction and the width direction of the main body. Each of the plurality of second extension tabs may be inclined toward the longitudinal end of the main body as it moves away from the composite layer.

[0010] The length of the front end region may be 10% to 15% of the length of the body, and the length of the end end region may be 60% to 80% of the length of the body. The body may include an insulating layer positioned in contact with the composite layer, and the substrate tab may be positioned in contact with the insulating layer.

[0011] According to one embodiment, a secondary battery includes an electrode assembly in which a first electrode and a second electrode are laminated and wound together with a separator, a can accommodating the electrode assembly in an internal space, and a cap plate coupled to an open end of the can to seal the can. At least one of the first electrode and the second electrode includes a body and a substrate tab. The body is composed of a substrate and a composite layer. The substrate tab is positioned on one side of the body at a distance from the composite layer and is bent from the body. The substrate tab includes a plurality of first extension tabs having a trapezoidal shape whose height gradually changes along a longitudinal direction of the body, and a plurality of second extension tabs having a parallelogram shape and having the same height.

[0012] The substrate tabs may be divided into a leading region, a middle region, and a terminal region. Non-extended tabs may be located in the leading region. A plurality of first extended tabs may be located in the middle region, and a plurality of second extended tabs may be located in the terminal region. The height of the plurality of first extended tabs may increase as they move away from the leading region.

[0013] The plurality of second extension tabs may have a constant width and may be defined by a plurality of cut lines inclined at a constant angle with respect to the longitudinal direction and the width direction of the main body. Each of the plurality of second extension tabs may be inclined toward the longitudinal end of the main body as it moves away from the composite layer.

[0014] The length of the front end region may be 10% to 15% of the length of the body, and the length of the end end region may be 60% to 80% of the length of the body. The body may include an insulating layer positioned in contact with the composite layer, and the substrate tab may be positioned in contact with the insulating layer.

[0015] An electrode assembly according to an embodiment can smoothly bend a plurality of expansion tabs, and can minimize the occurrence of defects such as cracks by distributing stress when bending the plurality of expansion tabs. Accordingly, the finishing quality of the bent substrate tabs can be improved, and the welding quality between the substrate tabs and the current collector plate can be improved, thereby increasing current collection efficiency. A secondary battery according to an embodiment can minimize internal resistance and increase output.

[0016] Figure 1 is a schematic diagram showing a winding process of an electrode assembly according to one embodiment.

[0017] Fig. 2 is a plan view showing the unfolded state of the first electrode of the electrode assembly illustrated in Fig. 1.

[0018] Fig. 3 is a cross-sectional view of the first electrode taken along line AA of Fig. 2.

[0019] Fig. 4 is a plan view showing the unfolded state of the second electrode of the electrode assembly illustrated in Fig. 1.

[0020] Fig. 5 is a cross-sectional view of the second electrode taken along the BB line of Fig. 3.

[0021] Figures 6a to 6c are schematic cross-sectional views of an electrode assembly according to one embodiment.

[0022] Fig. 7 is a partially enlarged view of the middle region of the first electrode shown in Fig. 2.

[0023] Fig. 8 is a partially enlarged view of the terminal side region of the first electrode illustrated in Fig. 2.

[0024] Figure 9 is a partial plan view of the electrode assembly shown in Figure 6c.

[0025] Figure 10 is a schematic diagram of a first electrode according to a comparative example.

[0026] Fig. 11 is a perspective view of a secondary battery according to one embodiment.

[0027] Figure 12 is a schematic cross-sectional view of the secondary battery illustrated in Figure 11.

[0028] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0029] Figure 1 is a schematic diagram showing a winding process of an electrode assembly according to one embodiment.

[0030] Referring to Fig. 1, the electrode assembly (100) of the present embodiment is a rolled electrode assembly for a cylindrical battery. The electrode assembly (100) is configured such that a first electrode (110) and a second electrode (120) are laminated and rolled with a separator (130) interposed therebetween. Each of the first electrode (110), the second electrode (120), and the separator (130) is formed in a strip shape extending long along the rolling direction.

[0031] The electrode assembly (100) may be configured such that a second electrode (120), a separator (130), a first electrode (110), and a separator (130) are sequentially stacked and then wound in a circular shape around a center pin (200). At this time, the second electrode (120) may be positioned closer to the center pin (200) than the first electrode (110), but the arrangement of the first electrode (110) and the second electrode (120) is not limited to the illustrated example. The center pin (200) may remain in the electrode assembly (100) or may be separated from the electrode assembly (100) after the electrode assembly (100) is wound.

[0032] Fig. 2 is a plan view showing the unfolded state of the first electrode of the electrode assembly illustrated in Fig. 1, and Fig. 3 is a cross-sectional view of the first electrode taken along line AA of Fig. 2.

[0033] Referring to FIGS. 2 and 3, the first electrode (110) includes a main body (10) including a first substrate (11) and a first composite layer (12), and a substrate tab (20) positioned on one side (upper side based on the drawing) of the main body (10) at a certain distance from the first composite layer (12). The main body (10) may include an insulating layer (13) in contact with the first composite layer (12), and the substrate tab (20) may be positioned in contact with the insulating layer (13). The substrate tab (20) may be a portion of one side (upper side) of the first substrate (11) that is not covered by the first composite layer (12) and the insulating layer (13).

[0034] The first electrode (110) may include a leading end (31) located at the center of the electrode assembly (100) and a terminal end (32) located at the outermost edge of the electrode assembly (100). The first composite layer (12) and the insulating layer (13) may have a constant width and may be positioned lengthwise along the longitudinal direction (L direction) of the first electrode (110).

[0035] The substrate tab (20) is a portion to be fixed to the first collector plate (not shown), and has the function of collecting the current of the main body (10) and transmitting it to the first collector plate. The substrate tab (20) may have different shapes in three regions. The three regions may include a front region (A10) in contact with the front end (31), a terminal region (A30) in contact with the terminal end (32), and a middle region (A20) located between the front region (A10) and the terminal region (A30). The substrate tab (20) includes a plurality of extension tabs (22, 23) located in the middle region (A20) and the terminal region (A30), and may be processed by laser cutting.

[0036] The first substrate (11) may be composed of a metal sheet having excellent electrical conductivity, such as aluminum foil or aluminum mesh. The first composite layer (12) may be manufactured by a process of preparing a slurry containing an active material, a conductive material, a binder, etc., applying the slurry to both sides of the first substrate (11), and drying and compressing the applied slurry. The first substrate (11) provides a path for the movement of charges generated in the first composite layer (12) and supports the first composite layer (12).

[0037] The active material of the first composite layer (12) may be composed of a compound capable of reversible intercalation and deintercalation of lithium, and specifically may include at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. For example, the active material of the first composite layer (12) may include a transition metal oxide such as LiCoO2, LiNiO2, LiMn2O4, Li(NiCoAl)O2, LiFePO4, Li(NiCoMn)O2, etc.

[0038] The insulating layer (13) may include an inorganic material. The inorganic material may be a ceramic, and the ceramic may be one or more of aluminum oxide (Al2O3), barium titanium oxide (BaTiO4), titanium oxide (TiO2), and silicon oxide (SiO2). The thickness of the insulating layer (13) may be less than or equal to the thickness of the first composite layer (12), but is not limited to this example. The first electrode (110) may be referred to as an anode.

[0039] Fig. 4 is a plan view showing the unfolded state of the second electrode of the electrode assembly illustrated in Fig. 1, and Fig. 5 is a cross-sectional view of the second electrode taken along the BB line of Fig. 3.

[0040] Referring to FIGS. 4 and 5, the second electrode (120) includes a main body (40) including a second substrate (41) and a second composite layer (42), and a substrate tab (50) positioned on the other side (lower side based on the drawing) of the main body (40) at a certain distance from the second composite layer (42). The substrate tab (50) may be the other side (lower side) edge portion of the second substrate (41) that is not covered by the second composite layer (42). The substrate tab (50) of the second electrode (120) is positioned on the opposite side from the substrate tab (20) of the first electrode (110).

[0041] The second electrode (120) may include a leading end (61) positioned at the center of the electrode assembly (100) and a terminal end (62) positioned at the outermost edge of the electrode assembly (100). The second composite layer (42) may have a constant width and may be positioned lengthwise along the longitudinal direction (L direction) of the second electrode (120).

[0042] The substrate tab (50) is a portion to be fixed to the second collector plate (not shown) and functions to collect the current of the main body (40) and transmit it to the second collector plate. The substrate tab (50) may have different shapes in the front end region (A10), the middle region (A20), and the end end region (A30). The substrate tab (50) may include a plurality of extension tabs (52, 53) located in the middle region (A20) and the end end region (A30), and may be processed by laser cutting.

[0043] The second substrate (41) may be composed of a metal sheet having excellent electrical conductivity, such as copper foil, copper mesh, nickel foil, or nickel mesh. The second composite layer (42) may be manufactured by a process of preparing a slurry containing an active material, a conductive material, a binder, etc., applying the slurry to both sides of the second substrate (41), and drying and compressing the applied slurry. The second substrate (41) provides a path for the movement of charges generated in the second composite layer (42) and supports the second composite layer (42).

[0044] The active material of the second composite layer (42) may include a material capable of reversible intercalation and deintercalation of lithium ions, such as a carbon-based material. The active material of the second composite layer (42) may include at least one of crystalline carbon and amorphous carbon. The second electrode (120) may be referred to as a negative electrode.

[0045] Referring to FIGS. 1 to 5, the separator (130) may be composed of a porous substrate or a porous substrate having a coating layer positioned on at least one surface. The porous substrate may include one or more of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester, polycarbonate, and polyimide. The coating layer may include a binder, and the binder may include a polyvinylidene fluoride-based compound. The separator (130) insulates the first electrode (110) and the second electrode (120) while allowing the movement of lithium ions.

[0046] In the case where the first composite layer (12) and the second composite layer (42) in the secondary battery directly face each other, a short circuit may occur, so this situation must be prevented. For example, when the secondary battery is exposed to high temperatures, the separator (130) may shrink, causing a portion of the first composite layer (12) and a portion of the second composite layer (42) to directly face each other, and even when the alignment of the first electrode (110), the separator (130), and the second electrode (120) is misaligned, a portion of the first composite layer (12) and a portion of the second composite layer (42) may directly face each other.

[0047] The insulating layer (13) may be provided on the first electrode (110) so as to face the upper edge of the second substrate (41) and a portion of the second composite layer (42) with the separator (130) interposed therebetween. Accordingly, in a situation where there is a risk that the first composite layer (12) and the second composite layer (42) may directly face each other, such as when the secondary battery is exposed to high temperature and the separator (130) shrinks, or when the alignment of the first electrode (110) and the second electrode (120) is slightly misaligned during the winding process of the electrode assembly (100), the insulating layer (13) faces the second composite layer (42) instead of the first composite layer (12), thereby preventing a short circuit from occurring.

[0048] Referring again to FIG. 2, the substrate tab (20) of the first electrode (110) may include a non-extended tab (21) located in the front end region (A10), a plurality of first extended tabs (22) located in the middle region (A20), and a plurality of second extended tabs (23) located in the end end region (A30).

[0049] The non-extended tabs (21) may have a constant height (first height, h1). The plurality of first extended tabs (22) have a trapezoidal shape, and the heights of the plurality of first extended tabs (22) may gradually change along the longitudinal direction (L direction) of the first electrode (110). The plurality of second extended tabs (23) may have the same height (second height, h2). The second height (h2) is greater than the first height (h1). The heights of the plurality of first extended tabs (22) are greater than the first height (h1) and less than the second height (h2).

[0050] The height of the plurality of first extension tabs (22) may increase as they move away from the front end region (A10). All of the plurality of first extension tabs (22) may have different heights. On the other hand, the substrate tabs of the middle region (A20) may be classified into a plurality of groups having different heights, and at least two first extension tabs (22) may be positioned within each group. The first case is illustrated as an example in Fig. 2.

[0051] Referring to FIGS. 2 and 4, the substrate tab (50) of the second electrode (120) may have the same configuration as the substrate tab (20) of the first electrode (110). That is, the substrate tab (50) of the second electrode (120) may include a non-extended tab (51) positioned in the front end region (A10), a plurality of third extended tabs (52) positioned in the middle region (A20), and a plurality of fourth extended tabs (53) positioned in the end end region (A30). The plurality of third extended tabs (52) may have the same configuration as the plurality of first extended tabs (22), and the plurality of fourth extended tabs (53) may have the same configuration as the plurality of second extended tabs (23).

[0052] Figures 6a to 6c are schematic cross-sectional views of an electrode assembly according to one embodiment. Figure 6a illustrates a front end region (A10) of a first electrode (110) and a second electrode (120), Figure 6b illustrates a middle region (A20) of the first electrode (110) and the second electrode (120), and Figure 6c illustrates a terminal end region (A30) of the first electrode (110) and the second electrode (120).

[0053] Referring to FIGS. 6A to 6C, a plurality of expansion tabs (22, 23) positioned on a first electrode (110) may be first bent toward the winding center of the electrode assembly (100) by being pushed by high-pressure air during the winding process of the electrode assembly (100), and may be secondarily bent by being pressed by a jig (not shown) after the winding of the electrode assembly (100). The plurality of expansion tabs (22, 23) may be flattened by the second bending so as to overlap with the expansion tabs (22, 23) positioned inside them. The folded plurality of expansion tabs (22, 23) may then be fixed to a first collector plate (not shown) by a method such as laser welding.

[0054] A plurality of expansion tabs (52, 53) positioned on the second electrode (120) can be first bent toward the winding center of the electrode assembly (100) by being pushed by high-pressure air during the winding process of the electrode assembly (100), and can be secondarily bent by being pressed by a jig (not shown) after the winding of the electrode assembly (100). The plurality of expansion tabs (52, 53) can be flattened by the second bending so as to overlap with the expansion tabs (52, 53) positioned inside them. The folded plurality of expansion tabs (52, 53) can then be fixed to the second collector plate (not shown) by a method such as laser welding.

[0055] A typical electrode assembly undergoes volume changes such as expansion during the charging process and contraction during the discharging process, and this volume change is mainly due to a volume change of the second composite layer. The non-expanded tab (21) of the tip region (A10) has the smallest height among the base tabs (20) of the first electrode (110) and is positioned parallel to the main body (10). Therefore, the non-expanded tab (21) maintains a sufficient distance from the second composite layer (42) so that it can maintain insulation from the second composite layer (42) even when the second composite layer (42) expands, thereby suppressing the occurrence of a short circuit.

[0056] However, since the non-extended tab (21) is not a part connected to the first collector plate, the resistance of the first electrode (110) increases as the length of the non-extended tab (21) increases. The length of the front end area (A10) where the non-extended tab (21) is located may be approximately 10% to 15% of the length of the first electrode (110).

[0057] Fig. 7 is a partially enlarged view of the middle region of the first electrode shown in Fig. 2.

[0058] Referring to FIGS. 2 and 7, each of the plurality of first extension tabs (22) in the middle region (A20) includes two first side portions (221) that are inclined in a diagonal direction. The two first side portions (221) are not parallel to each other and have a predetermined inclination angle with respect to the width direction (W direction) of the first electrode (110). The two first side portions (221) can be symmetrical left and right with respect to the center line (CC line) of the first extension tab (22).

[0059] The plurality of first expansion tabs (22) form a trapezoidal shape and have a multi-step structure in which the height gradually increases toward the longitudinal end (32). In this structure, the first expansion tabs (22) having a relatively small height are bent first, and then the first expansion tabs (22) having a relatively large height are bent to cover the first expansion tabs (22) located inside them from above. Therefore, in the above-described structure, the plurality of first expansion tabs (22) can be bent smoothly, and the stress applied to the first expansion tabs (22) can be distributed as much as possible, so that defects such as the occurrence of cracks can be minimized.

[0060] The length of the intermediate region (A20) where the plurality of first extension tabs (22) are positioned may be approximately 5% to 30% of the length of the first electrode (110). The sum of the length of the tip region (A10) and the length of the intermediate region (A20) may be approximately 20% to 40% of the length of the first electrode (110).

[0061] Fig. 8 is a partially enlarged view of the terminal side region of the first electrode illustrated in Fig. 2.

[0062] Referring to FIGS. 2 and 8, a plurality of diagonally inclined cutting lines (CL) are positioned on the substrate tab of the end-side region (A30) to define a plurality of second expansion tabs (23). At this time, the diagonal direction is a direction inclined at a predetermined angle with respect to both the longitudinal direction (L direction) and the width direction (W direction) of the first electrode (110), and has a constant inclination.

[0063] Each of the plurality of second extension tabs (23) includes two second side portions (231) that are inclined in a diagonal direction. The two second side portions (231) are parallel to each other and have the same inclination angle with respect to the longitudinal direction (L direction) and the width direction (W direction) of the first electrode (110). The plurality of second extension tabs (23) may have the same width and may have a shape that is inclined toward the terminal end portion (32) as they get farther away from the insulating layer (13).

[0064] After all of the plurality of first expansion tabs (22) are bent, the plurality of second expansion tabs (23) are sequentially bent so that the plurality of second expansion tabs (23) first cover the bent first expansion tabs (22) from above, and then cover the second expansion tabs (23) located inside them from above. In the process of bending the plurality of second expansion tabs (23), the second expansion tabs (23) can reduce the overlapping area with the neighboring second expansion tabs (23) along the longitudinal direction (L direction) of the first electrode (110) due to the parallelogram structure.

[0065] Figure 9 is a partial plan view of the electrode assembly shown in Figure 6c.

[0066] Referring to FIGS. 8 and 9, two adjacent second extension tabs (23) along the longitudinal direction of the first electrode (110) are positioned with an inclined cutting line (CL) interposed therebetween. The second extension tab (23) formed in the shape of a parallelogram has a portion (23A) that overlaps with the adjacent second extension tab (23) during the process of being vertically bent from the main body (10).

[0067] Figure 10 is a schematic diagram of a first electrode according to a comparative example.

[0068] Referring to Fig. 10, in the first electrode (210) of the comparative example, a plurality of second expansion tabs (70) are positioned with a cutting line (CL1) parallel to the width direction (W direction) of the first electrode (210) interposed therebetween. The second expansion tab (70) of the comparative example, which is rectangular, has a portion (70A) that overlaps with an adjacent second expansion tab (70) during the process of being vertically bent from the main body.

[0069] Referring to FIGS. 9 and 10, the area of ​​the portion (23A) where adjacent second expansion tabs (23) overlap each other in the first electrode (110) of the embodiment is smaller than the area of ​​the portion (70A) where adjacent second expansion tabs (70) overlap each other in the comparative example. In the first electrode (210) of the comparative example, when bending a plurality of second expansion tabs (70), the area where adjacent second expansion tabs (70) overlap each other becomes larger, making it difficult to bend the second expansion tabs (70), and stress may be concentrated on the second expansion tabs (70), which may cause defects such as cracks.

[0070] The electrode assembly (100) of the present embodiment can smoothly bend the second expansion tab (23) by reducing the area (23A) of the overlapping portion between adjacent second expansion tabs (23), and can minimize defects such as cracks by dispersing the stress applied to the second expansion tab (23). This function is equally applied to the fourth expansion tab (53) located on the second electrode (120).

[0071] The length of the terminal-side region (A30) where the plurality of second extension tabs (23) are positioned may be more than half the length of the first electrode (110), and may be approximately 60% to 80% of the length of the first electrode (110). Since the plurality of second extension tabs (23) substantially function to transfer the current of the first electrode (110) to the first collector plate, the length of the terminal-side region (A30) may be more than 60% of the length of the first electrode (110) in order to secure current collection performance.

[0072] The electrode assembly (100) of the present embodiment can reduce defects in the substrate tabs (20, 50) and improve the finishing quality of the bent substrate tabs (20, 50) by configuring the second extension tabs (23) and the fourth extension tabs (53) described above. The improvement in the finishing quality of the substrate tabs (20) leads to an improvement in the welding quality with the first and second collector plates and an improvement in the current collection efficiency.

[0073] FIG. 11 is a perspective view of a secondary battery according to one embodiment, and FIG. 12 is a schematic cross-sectional view of the secondary battery illustrated in FIG. 11.

[0074] Referring to FIGS. 11 and 12, the secondary battery (300) of the present embodiment includes an electrode assembly (100) having the above-described configuration, a can (310) that accommodates the electrode assembly (100), first and second current collector plates (140, 150), and an electrolyte in an internal space, and a cap plate (320) that is coupled to an open end of the can (310) to seal the can (310). The first current collector plate (140) is fixed to a folded substrate tab (20) of the first electrode, and the second current collector plate (150) is fixed to a folded substrate tab (50) of the second electrode.

[0075] The can (310) is formed in a shape in which one side (top) is open so that the electrode assembly (100) and the first and second collector plates (140, 150) can be inserted. The can (310) may include a circular bottom portion (311) and a cylindrical side portion (312) connected to the edge of the bottom portion (311). The bottom portion (311) may be referred to as a top portion when the top and bottom of the secondary battery (300) are reversed.

[0076] A terminal hole may be located in the center of the bottom portion (311), and a rivet terminal (330) may be installed in the terminal hole via a first insulator (81). The first insulator (81) insulates the bottom portion (311) and the rivet terminal (330), and seals the terminal hole to prevent leakage of the electrolyte. The rivet terminal (330) may be connected to the first current collector (140) and may be charged with the same polarity as the first electrode, and may function as a first terminal (positive terminal).

[0077] After the electrode assembly (100) and the first and second collector plates (140, 150) are accommodated inside the can (310), the side portion (312) can be formed to have a beading portion (313) by conventional press processing. The beading portion (313) is a portion that is sunken toward the inside of the can (310) and has the function of suppressing movement of the electrode assembly (100).

[0078] The second collector plate (150) may include a conductive portion (151) that is in close contact with the inner surface of the beading portion (313). The conductive portions (151) may be provided in multiple numbers along the edge of the second collector plate (150). The can (310) may be charged with the same polarity as the second electrode by the conductive portion (151) and may function as a second terminal (negative terminal). At this time, a second insulator (82) may be positioned between the bottom portion (311) and the first collector plate (140) to insulate the bottom portion (311) and the first collector plate (140).

[0079] The side portion (312) can be formed to have a crimping portion (314) by conventional press processing. The crimping portion (314) can be a portion in which the opening-side end of the side portion (312) is vertically bent toward the inside of the can (310). The edge of the cap plate (320) can be pressed between the beading portion (313) and the crimping portion (314) via the third insulator (83), and the cap plate (320) can be firmly fixed to the end of the side portion (312). The cap plate (320) can be electrically non-polar by being insulated from the first electrode and the second electrode.

[0080] A notch groove (321) may be positioned on the inner surface of the cap plate (320). The notch groove (321) may have a V-shaped cross-section, and may be in the shape of an arc on the bottom surface (when the target object is viewed from above). The internal temperature of the secondary battery (300) may rise due to various reasons such as rapid charging and discharging, external impact, exposure to a high-temperature environment, etc., and the internal pressure may rise due to evaporation of the electrolyte, etc. When the internal pressure of the secondary battery (300) rises, the cap plate (320) may break around the notch groove (321) to discharge internal gas.

[0081] In the secondary battery (300) of the above-described configuration, the electrode assembly (100) can smoothly bend the plurality of expansion tabs (22, 23, 52, 53), and can minimize the occurrence of defects such as cracks by distributing stress when bending the plurality of expansion tabs (22, 23, 52, 53). Accordingly, the finishing quality of the bent base tabs (20, 50) can be improved, and the welding quality of the base tabs (20, 50) and the current collector plate (140, 150) can be improved, thereby increasing the current collection efficiency. The secondary battery (300) of the present embodiment can increase the output by minimizing the internal resistance.

[0082] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Separator; and It includes a first electrode and a second electrode positioned with the separator between them and wound together with the separator, At least one of the first electrode and the second electrode, A main body composed of a substrate and a composite layer, and including a front end and a longitudinal end; and A plurality of extension tabs are positioned on one side of the main body at a distance from the composite layer along the width direction of the main body, and are positioned closer to the longitudinal end than the leading end along the longitudinal direction of the main body, and are bent from the main body. An electrode assembly in which the plurality of extension tabs are defined by a plurality of cut lines inclined at a constant angle with respect to the longitudinal direction of the main body and the width direction of the main body.

2. In paragraph 1, An electrode assembly wherein the plurality of extension tabs have a constant width and are inclined toward the terminal end as they move away from the composite layer.

3. In paragraph 2, An electrode assembly wherein the total length of the plurality of extension tabs along the longitudinal direction of the main body is greater than half the length of the main body.

4. In any one of paragraphs 1 to 3, The above body includes an insulating layer positioned in contact with the composite layer, An electrode assembly in which the above plurality of extension tabs are positioned in contact with the above insulating layer.

5. Separator; and It includes a first electrode and a second electrode positioned with the separator between them and wound together with the separator, At least one of the first electrode and the second electrode, A body composed of a substrate and a composite layer; and A substrate tab is positioned on one side of the main body at a distance from the composite layer and is bent from the main body, The above-mentioned substrate tab comprises an electrode assembly including a plurality of first extension tabs having a trapezoidal shape whose height gradually changes along the longitudinal direction of the main body, and a plurality of second extension tabs having the same height and having a parallelogram shape.

6. In paragraph 5, The above description tab is divided into a front end area, a middle area, and a longitudinal area, A non-extended tab is located in the above-mentioned front-end area, The above plurality of first extension tabs are located in the middle area, The electrode assembly wherein the plurality of second extension tabs are located in the terminal side region.

7. In paragraph 6, An electrode assembly in which the height of the plurality of first extension tabs increases as they move away from the tip side region.

8. In paragraph 6, An electrode assembly in which the plurality of second extension tabs have a constant width and are defined by a plurality of cutting lines inclined at a constant angle with respect to the longitudinal and width directions of the main body.

9. In paragraph 8, An electrode assembly wherein each of the plurality of second extension tabs is inclined toward the terminal end of the main body as it moves away from the composite layer.

10. In paragraph 6, The length of the above-mentioned tip region is 10% to 15% of the length of the above-mentioned main body, An electrode assembly in which the length of the above terminal region is 60% to 80% of the length of the main body.

11. In any one of paragraphs 5 to 19, The above body includes an insulating layer positioned in contact with the composite layer, The above-described tab is an electrode assembly positioned in contact with the above-described insulating layer.

12. An electrode assembly in which a first electrode and a second electrode are laminated and wound together with a separator; A can accommodating the electrode assembly in an internal space; and A cap plate is included that is joined to the opening end of the can to seal the can, At least one of the first electrode and the second electrode, A body composed of a substrate and a composite layer; and A substrate tab is positioned on one side of the main body at a distance from the composite layer and is bent from the main body, A secondary battery comprising a plurality of first extension tabs having a trapezoidal shape whose height gradually changes along the longitudinal direction of the main body, and a plurality of second extension tabs having the same height and having a parallelogram shape.

13. In paragraph 12, The above description tab is divided into a front end area, a middle area, and a longitudinal area, A non-extended tab is located in the above-mentioned front-end area, The above plurality of first extension tabs are located in the middle area, The secondary battery wherein the plurality of second extension tabs are located in the terminal side region.

14. In paragraph 13, A secondary battery in which the height of the plurality of first expansion tabs increases as they move away from the tip-side region.

15. In paragraph 13, A secondary battery in which the plurality of second extension tabs have a constant width and are divided by a plurality of cutting lines inclined at a constant angle with respect to the longitudinal direction and the width direction of the main body.

16. In paragraph 15, A secondary battery in which each of the plurality of second extension tabs is inclined toward the terminal end of the main body as it moves away from the composite layer.

17. In paragraph 13, The length of the above-mentioned tip region is 10% to 15% of the length of the above-mentioned main body, A secondary battery in which the length of the above-mentioned end region is 60% to 80% of the length of the above-mentioned main body.

18. In any one of paragraphs 12 to 17, The above body includes an insulating layer positioned in contact with the composite layer, The above-mentioned secondary battery tab is positioned in contact with the above-mentioned insulating layer.

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