Battery case and secondary battery including same

Abstract

A battery case according to an embodiment of the present invention may comprise an accommodation part that accommodates an electrode assembly in which a positive electrode and a negative electrode are alternately stacked with a separator interposed therebetween, and an edge portion of the negative electrode protrudes further outward than the positive electrode. The bottom surface of the accommodation part may comprise: a main region; and a peripheral region that is located around the main region, forms a predetermined step difference with the main region, and overlaps the edge portion of the negative electrode with respect to the stacking direction of the electrode assembly.

Description

Battery case and secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0127466, filed September 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a battery case that accommodates an electrode assembly including a positive electrode and a negative electrode larger than the positive electrode, and a secondary battery including the electrode assembly and the battery case.

[0005] Common types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. These batteries are used not only in small products such as digital cameras, DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in larger products requiring high output, such as electric and hybrid vehicles, as well as in power storage devices that store surplus power or renewable energy, and as backup power storage devices.

[0006] To manufacture these secondary batteries, first, an electrode active material slurry is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and these are laminated on both sides of a separator to form an electrode assembly of a predetermined shape. Then, the electrode assembly is housed in a battery case, filled with electrolyte, and sealed.

[0007] Secondary batteries are classified into pouch type and can type, depending on the material of the case housing the electrode assembly. Pouch type batteries house the electrode assembly in a pouch made of a flexible polymer material. Can type batteries house the electrode assembly in a case made of materials such as metal or plastic.

[0008] Typically, pouch-type battery cases are manufactured by pressing a flexible pouch film to form a cup-shaped receptacle. Once the receptacle is formed, an electrode assembly is housed within the receptacle and the sides are sealed to manufacture a secondary battery.

[0009] The pouch-type battery case is formed to accommodate the thickness of the electrode assembly, taking insertability into consideration. However, the positive and negative electrodes included in the electrode assembly differ in size. Specifically, the negative electrode is typically formed larger than the positive electrode. This size difference results in a slight thickness difference between the center and edges of the electrode assembly.

[0010] In the past, the receiving portion of a pouch-type battery case was formed to a uniform depth without considering such a difference in thickness, which resulted in the creation of empty space within the receiving portion, which could potentially cause safety issues such as lithium precipitation or electrode migration.

[0011] The problem to be solved by the present invention is to provide a battery case and secondary battery in which empty space within a receiving portion is minimized by compensating for the difference in thickness of an electrode assembly due to the difference in size between the positive and negative electrodes.

[0012] A battery case according to an embodiment of the present invention may include a receiving portion for receiving an electrode assembly in which a positive electrode and a negative electrode are alternately stacked with a separator in between, and an edge portion of the negative electrode protrudes outward from the positive electrode. A bottom surface of the receiving portion may include a main region; and a peripheral region positioned around the periphery of the main region, forming a predetermined step with respect to the main region and overlapping an edge portion of the negative electrode with respect to the stacking direction of the electrode assembly.

[0013] The above battery case may further include a terrace portion connected to the peripheral surface of the receiving portion. Based on the terrace portion, the depth of the main region may be deeper than the depth of the peripheral region.

[0014] The above-mentioned receiving portion may include a first receiving portion and a second receiving portion facing each other. The bottom surface of each of the first receiving portion and the second receiving portion may include the main region and the peripheral region.

[0015] The above perimeter region may have a closed loop shape.

[0016] A secondary battery according to an embodiment of the present invention may include a battery case having an electrode assembly in which a positive electrode and a negative electrode are alternately stacked with a separator therebetween, with an edge portion of the negative electrode protruding outward from the positive electrode; and a receiving portion for accommodating the electrode assembly. A bottom surface of the receiving portion may include a main region; and a peripheral region positioned around the periphery of the main region, forming a predetermined step with respect to the main region and overlapping an edge portion of the negative electrode with respect to the stacking direction of the electrode assembly.

[0017] The width of the above peripheral region may correspond to the width of the edge of the cathode.

[0018] The step between the main region and the peripheral region may correspond to half of the total thickness of the anode included in the electrode assembly.

[0019] The above-mentioned peripheral region may include a tab section extending parallel to a side from which a cathode tab protrudes from the cathode; and a side section extending in a direction perpendicular to the tab section and having a narrower width than the tab section.

[0020] A secondary battery according to an embodiment of the present invention may include an electrode assembly in which a positive electrode and a negative electrode are alternately stacked with a separator therebetween, wherein an edge of the negative electrode protrudes outward more than the positive electrode; a battery case having a receiving portion for accommodating the electrode assembly; and a pad disposed at least on one side of the receiving portion with respect to the stacking direction of the electrode assembly. The pad may include a support portion having a predetermined thickness and overlapping with an edge of the negative electrode with respect to the stacking direction of the electrode assembly.

[0021] The width of the above support may correspond to the width of the edge of the above cathode.

[0022] The above support may have a closed loop shape.

[0023] The thickness of the above support may correspond to the total thickness of the plurality of positive electrodes included in the electrode assembly.

[0024] The above pad may further include a cover portion located inside the support portion and having a thinner thickness than the support portion.

[0025] The difference between the thickness of the cover portion and the thickness of the support portion may correspond to the total thickness of the plurality of positive electrodes included in the electrode assembly.

[0026] The above pad can be in close contact with the inner side of the bottom surface of the receiving portion.

[0027] The above-mentioned receiving portion may include a first receiving portion and a second receiving portion that face each other. The pad may include a first pad positioned on one side with respect to the stacking direction of the electrode assembly and located within the first receiving portion; and a second pad positioned on the other side with respect to the stacking direction of the electrode assembly and located within the second receiving portion.

[0028] The support member may include a tab section extending parallel to a side from which a cathode tab protrudes from the cathode; and a side section extending in a direction perpendicular to the tab section and having a narrower width than the tab section.

[0029] According to a preferred embodiment of the present invention, the empty space within the receiving portion caused by the relatively thin thickness of the edge portion of the electrode assembly can be minimized, and problems such as lithium precipitation or electrode slippage that may occur in the electrode assembly due to the empty space can be resolved.

[0030] In addition, the configurations according to preferred embodiments of the present invention may include effects that can be easily predicted by those skilled in the art.

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

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

[0033] Figure 2 is a schematic diagram of the electrode assembly illustrated in Figure 1.

[0034] Figure 3 is a side view of a secondary battery according to one embodiment of the present invention.

[0035] FIG. 4 is a cross-sectional view showing the interior of a secondary battery according to one embodiment of the present invention, with the periphery of the bottom surface of the receiving portion being enlarged.

[0036] Figure 5 is a plan view of a secondary battery according to one embodiment of the present invention.

[0037] Figure 6 is a plan view of the electrode assembly illustrated in Figure 1.

[0038] Figure 7 is an exploded perspective view of a secondary battery according to another embodiment of the present invention.

[0039] FIG. 8 is a cross-sectional view showing the inside of a secondary battery according to another embodiment of the present invention, with the area around the support portion of the pad enlarged.

[0040] Figure 9 is a plan view of the pad illustrated in Figure 7.

[0041] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0042] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0043] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0044] In the drawing, each component of a secondary battery according to one embodiment of the present invention is schematically illustrated, and the size of the component or the thickness of the line may be expressed somewhat exaggerated for the convenience of understanding.

[0045] FIG. 1 is an exploded perspective view of a secondary battery according to one embodiment of the present invention, and FIG. 2 is a schematic diagram of the electrode assembly illustrated in FIG. 1.

[0046] A secondary battery (10) according to one embodiment of the present invention may include a battery case (100) and an electrode assembly (200).

[0047] The battery case (100) may be a pouch-type battery case. The battery case (100) may include a receiving portion (110). More specifically, the battery case (100) may be manufactured by sealing a first case (101) and a second case (102) with each other, and a receiving portion (110) may be formed in at least one of the first case (101) and the second case (102).

[0048] As illustrated in FIG. 1, when a receiving portion (110) is formed in each of the first case (101) and the second case (102), the battery case (100) may include a pair of receiving portions (110). If necessary, the receiving portion (110) of the first case (101) may be referred to as a first receiving portion, and the receiving portion (110) of the second case (102) may be referred to as a second receiving portion. The pair of receiving portions (110) may face each other and together define a receiving space for receiving the electrode assembly (200). The pair of receiving portions (110) may be formed to have the same or different depths. The sum of the depths of the pair of receiving portions (110) may be approximately the same as or similar to the thickness of the electrode assembly (200).

[0049] On the other hand, if the receiving portion (110) is formed in only one of the first case (101) and the second case (102), the battery case (100) may include a single receiving portion (110). The receiving portion (110) may solely define a receiving space for receiving the electrode assembly (200). The depth of the receiving portion may be approximately equal to or similar to the thickness of the electrode assembly (200).

[0050] Each receiving portion (110) may include a bottom surface (111) and a peripheral surface (114). The bottom surface (111) of the receiving portion (110) may face the electrode assembly (200) in the thickness direction. The peripheral surface (114) of the receiving portion (110) may surround the periphery of the electrode assembly (200).

[0051] The detailed configuration of the bottom surface (111) of the receiving portion (110) will be described in detail later.

[0052] The battery case (100) may further include a terrace portion (120) connected to the peripheral surface (114) of the receiving portion (110). The terrace portion (120) may be formed approximately parallel to the bottom surface (111) of the receiving portion (110).

[0053] For example, when a receiving portion (110) is formed in each of the first case (101) and the second case (102), the first case (101) and the second case (102) may each include a terrace portion (120). The terrace portion (120) of the first case (101) and the terrace portion (120) of the second case (102) may be sealed while in contact with each other, thereby allowing the electrode assembly (200) to be sealed within the battery case (100).

[0054] As another example, if the receiving portion (110) is formed only in the first case (101), the first case (101) may include a terrace portion (120). In addition, the second case (102) may have a flat shape. The terrace portion (120) of the first case (101) may be sealed while in contact with the second case (102), thereby allowing the electrode assembly (200) to be sealed within the battery case (100).

[0055] As illustrated in Fig. 1, the first case (101) and the second case (102) may be separate members. In this case, the first case (101) and the second case (102) may be sealed at four sides while in contact with each other so as to face each other.

[0056] However, it is not limited thereto, and the first case (101) and the second case (102) may be connected to share one side. In this case, when the one side is folded, the first case (101) and the second case (102) may come into contact so as to face each other, and in this state, the remaining three sides excluding the one side may be sealed.

[0057] Meanwhile, the electrode assembly (200) may have a positive electrode (210) and a negative electrode (220) alternately stacked with a separator (230) in between. That is, the electrode assembly (200) may include a positive electrode (210), a negative electrode (220), and a separator (230). The electrode assembly (200) may be formed in various forms, such as a stack type, a winding type, a stack and folding type, etc., and since this is a well-known technology, a description thereof will be omitted.

[0058] Each electrode (210)(220) may be provided with an electrode tab (210a)(220a). The electrode tab (210a)(220a) is connected to the electrode (210)(220) and may protrude outward.

[0059] More specifically, each anode (210) may be provided with an anode tab (210a), and each cathode (220) may be provided with a cathode tab (220a). The anode tabs (210a) of a plurality of anodes (210) may be joined together and welded. The cathode tabs (220a) of a plurality of cathodes (220) may be joined together and welded.

[0060] As illustrated in FIG. 1, the positive electrode tab (210a) and the negative electrode tab (220a) may protrude in different directions with respect to the electrode assembly (200). However, this is not limited to the above, and the positive electrode tab (210a) and the negative electrode tab (220a) may also protrude in parallel in the same direction.

[0061] An electrode lead (240) (250) may be connected to the electrode tab (210a) (220a). One end of the electrode lead (240) (250) may be connected to the electrode tab (210a) (220a) and the other end may protrude to the outside of the battery case (100). The electrode lead (240) (250), together with the electrode tab (210a) (220a), may act as a path through which electrons may move between the inside and the outside of the electrode assembly (200).

[0062] In more detail, a positive lead (240) may be connected to the positive tab (210a), and a negative lead (250) may be connected to the negative tab (220a). The positive lead (240) may be connected to a portion where a plurality of positive tabs (210a) are joined and welded together. The negative lead (250) may be connected to a portion where a plurality of negative tabs (220a) are joined and welded together.

[0063] A portion of each electrode lead (240)(250) may be surrounded by an insulating material such as an insulating tape. The insulating material may be positioned between the first case (101) and the second case (102), and in this state, the first case (101) and the second case (102) may be sealed to each other. In this case, a portion of the inner surfaces of the first case (101) and the second case (102) may be sealed to the insulating material. Accordingly, the insulating material may prevent current from flowing to the battery case (100) through the electrode lead (240)(250) and maintain the sealing of the battery case (100).

[0064] Meanwhile, the cathode (220) generally has a larger size than the anode (210). That is, the edge of the cathode (220) may protrude outward more than the anode (210). The degree to which the cathode (220) protrudes more than the anode (210) can be defined as the width (g) of the edge of the cathode (220).

[0065] Due to the size difference between the positive electrode (210) and the negative electrode (220), the thickness of the electrode assembly (200) may be thicker at the edges than at the center. The central portion of the electrode assembly (200) may be a portion where the positive electrode (210), the negative electrode (220), and the separator (230) are laminated, and the edge portion of the electrode assembly (200) may be a portion where the edge portion of the negative electrode (220) and the separator (230) are laminated.

[0066] In more detail, the thickness of the central portion of the electrode assembly (200) may correspond to the total thickness of the positive electrode (210), the negative electrode (220), and the separator (230). On the other hand, the thickness of the edge portion of the electrode assembly (200) may correspond to the total thickness of the negative electrode (220) and the separator (230). That is, the thickness of the central portion of the electrode assembly (200) and the thickness of the edge portion of the electrode assembly (220) may differ by the total thickness of the positive electrode (210).

[0067] The difference between the thickness of the central portion and the thickness of the edge portion of the electrode assembly (200) may vary depending on the thickness of each anode (210) and the number of layers of the anodes (210).

[0068] FIG. 3 is a side view of a secondary battery according to one embodiment of the present invention, and FIG. 4 is a cross-sectional view illustrating the interior of a secondary battery according to one embodiment of the present invention, with an enlarged view of the periphery of the bottom surface of the receiving portion. To facilitate understanding, FIG. 4 illustrates the positive electrode (210), the negative electrode (220), and the separator (230) as being slightly spaced apart from each other, but those skilled in the art will readily understand that they are actually stacked on top of each other.

[0069] To compensate for the thickness difference between the central and peripheral portions of the electrode assembly (200), the receiving portion (110) of the battery case (100) may include a main region (112) and a peripheral region (113) formed with different depths.

[0070] In more detail, the bottom surface (111) of the receiving portion (110) may include a main area (112) and a peripheral area (113) located around the main area (112) and forming a predetermined step with the main area (112).

[0071] The peripheral region (113) may have a closed loop shape. The peripheral region (113) may surround the main region (112). The peripheral region (113) may be connected to the peripheral surface (114) of the receiving portion (110).

[0072] The peripheral region (113) may overlap with the edge portion of the cathode (220) with respect to the stacking direction of the electrode assembly (200). The width (W1) of the peripheral region (113) may correspond to the width (g) of the edge portion of the cathode (220). In the present specification, corresponding may mean identical or similar.

[0073] Based on the terrace section (120), the depth (d1) of the main area (112) may be deeper than the depth (d2) of the peripheral area (113). The step (S) between the main area (112) and the peripheral area (113) may mean the difference between the depth (d1) of the main area (112) and the depth (d2) of the peripheral area (113).

[0074] If the battery case (100) includes a pair of receiving portions (110), the bottom surface (111) of each receiving portion (110) may include the main region (112) and the peripheral region (113). In this case, the step (S) between the main region (112) and the peripheral region (113) may correspond to approximately half of the thickness difference between the central portion and the edge portion of the electrode assembly (200). That is, the step (S) between the main region (112) and the peripheral region (113) may correspond to half of the total thickness of the plurality of positive electrodes (210) included in the electrode assembly (200). For example, the step (S) may be 0.1 mm to 1 mm.

[0075] By the peripheral area (113) of the receiving portion (110), the empty space within the receiving portion (110) caused by the relatively thin thickness of the edge of the electrode assembly (200) can be minimized, and problems such as lithium precipitation or electrode slippage that may occur in the electrode assembly (200) due to the empty space can be resolved.

[0076] Fig. 5 is a plan view of a secondary battery according to one embodiment of the present invention, and Fig. 6 is a plan view of the electrode assembly illustrated in Fig. 1. To aid understanding, the illustration of the separator (230) is omitted in Fig. 6.

[0077] In the electrode assembly (200), the width (g) of the edge of the cathode (220) is not constant along the circumference of the cathode (220) and may be formed differently depending on the location. In this regard, for the stability of the electrode assembly (200), it is common to form the size difference between the cathode (220) and the anode (210) to be greater at the tab portion.

[0078] In more detail, the cathode (200) may include a first side from which a cathode tab (220a) protrudes, a second side parallel to the first side, and third and fourth sides perpendicular to the first and second sides. In addition, the second side may be adjacent to the side from which the cathode tab (210a) protrudes in the anode (210). In this case, the width (g1) of the edges of the first and second sides may be wider than the width (g2) of the edges of the third and fourth sides.

[0079] For example, as illustrated in FIG. 6, the negative electrode tab (220a) may protrude from the short side of the negative electrode (220), and the positive electrode tab (210a) may protrude from the short side of the positive electrode (210) in the opposite direction to the negative electrode tab (220a). In this case, the width (g1) of the edge portions of both short sides of the negative electrode (220) may be wider than the width (g2) of the edge portions of both long sides of the negative electrode (220).

[0080] In order to correspond to the width (g1, g2) of the edge of the cathode (220), the peripheral area (113) of the receiving portion (110) of the battery case (100) may include a tab section (113a) and a side section (113b) having a narrower width than the tab section (113a).

[0081] The tab section (113a) may extend parallel to the side from which the negative electrode tab (220a) protrudes from the negative electrode (220). The side section (113b) may extend in a direction perpendicular to the tab section (113a). More specifically, the tab section (113a) may be provided in a pair parallel to the first side and the second side of the negative electrode (220). The side section (113b) may be provided in a pair parallel to the third side and the fourth side of the negative electrode (220).

[0082] Each tab section (113a) may overlap with the edge of the first side or the second side of the cathode (220) with respect to the stacking direction of the electrode assembly (200). Each side section (113b) may overlap with the edge of the third side or the fourth side of the cathode (220) with respect to the stacking direction of the electrode assembly (200).

[0083] The width (W11) of the tab section (113a) may be wider than the width (W12) of the side section (113b).

[0084] The width (W11) of the tab section (113a) may correspond to the width (g1) of the edge of the first or second side of the cathode (220). The width (W12) of the side section (113b) may correspond to the width (g2) of the edge of the third or fourth side of the cathode (220).

[0085] For example, the width (W11) of the tab section (113a) may be 1 mm to 3 mm, and the width (W12) of the side section (113b) may be 1 mm to 2 mm. In addition, the width (W11) of the tab section (113a) may be 1 mm to 1.5 mm wider than the width (W12) of the side section (113b).

[0086] In this way, the peripheral area (113) of the receiving portion (110) can be optimized to match the shape of the edge of the electrode assembly (200), and the empty space within the receiving portion (110) can be minimized.

[0087] Fig. 7 is an exploded perspective view of a secondary battery according to another embodiment of the present invention, and Fig. 8 is an enlarged cross-sectional view showing the interior of a secondary battery according to another embodiment of the present invention, with the area around the support portion of the pads being depicted. To facilitate understanding, Fig. 8 shows the positive electrode (210), the negative electrode (220), and the separator (230) slightly spaced apart from each other, but those skilled in the art will readily understand that they are actually laminated.

[0088] Below, we will omit any overlapping information from what was previously explained and focus on explaining the differences.

[0089] A secondary battery (10') according to another embodiment of the present invention may further include a pad (300) instead of the receiving portion (110) of the battery case (100) being formed at a constant depth without a step. That is, in order to compensate for the thickness difference between the central portion and the edge portion of the electrode assembly (200), the secondary battery (10') may further include a pad (300).

[0090] The pad (300) may be placed on at least one side of the electrode assembly (200) with respect to the stacking direction within the receiving portion (110). More specifically, the pad (300) may be placed between the bottom surface (111) of the receiving portion (110) and the edge of the electrode assembly (200). The pad (300) may be in close contact with the inside of the bottom surface (111) of the receiving portion (110).

[0091] The pad (300) may be made of a material that is non-reactive with the electrolyte injected into the receiving portion (110). The pad (300) may be elastically deformed by an external force to accommodate a certain degree of thickness change. For example, the pad (300) may be in the form of a sponge or foam pad. The pad (300) has the additional advantage of being able to absorb excess electrolyte within the receiving portion (110) or prevent external impact from being transmitted to the electrode assembly (200).

[0092] When a receiving portion (110) is formed in each of the first case (101) and the second case (102), a pair of pads (300) may be provided. More specifically, the pair of pads (300) may include a first pad (300A) positioned on one side with respect to the stacking direction of the electrode assembly (200), and a second pad (300B) positioned on the other side with respect to the stacking direction of the electrode assembly (200). The first pad (300A) may be positioned within the receiving portion (110) of the first case (101), and the second pad (300B) may be positioned within the receiving portion (110) of the second case (102).

[0093] Each pad (300) may include a support portion (310) that overlaps with an edge portion of the cathode (220) with respect to the stacking direction of the electrode assembly (200). The pad (300) may further include a cover portion (320) that is positioned inward from the support portion (310) and has a thickness thinner than the support portion (310).

[0094] The cover portion (320) may be in the form of a thin film or sheet. The cover portion (320) may cover the electrode assembly (200).

[0095] The support portion (310) may have a closed loop shape. The support portion (310) may protrude from the cover portion (320) toward the electrode assembly (200). The support portion (310) may be attached to the cover portion (320). However, this is not limited thereto, and the support portion (310) and the cover portion (320) may also be formed integrally.

[0096] The outer circumference of the support portion (310) may face the inner circumference of the receiving portion (110). The support portion (310) may have a predetermined thickness.

[0097] The support (310) may overlap with the edge of the cathode (220) with respect to the stacking direction of the electrode assembly (200). The width (W2) of the support (310) may correspond to the width (g) of the edge of the cathode (220) (see FIG. 4).

[0098] The thickness of the support portion (310) may be thicker than the thickness of the cover portion (320). When the battery case (100) includes a pair of receiving portions (110), the thickness difference (t) between the support portion (310) and the cover portion (320) in each of the first pad (300A) and the second pad (300B) may correspond to approximately half of the thickness difference between the center portion and the edge portion of the electrode assembly (200). The thickness difference (t) between the support portion (310) and the cover portion (320) may correspond to half of the total thickness of the plurality of positive electrodes (210) included in the electrode assembly (200). For example, the thickness difference (t) may be 0.1 mm to 1 mm.

[0099] However, it is not limited thereto, and the pad (300) may be composed of only the support portion (310) without including the cover portion (320). That is, the pad (300) may have a closed loop shape. In this case, the thickness of the support portion (310) of each of the first pad (300A) and the second pad (300B) may correspond to approximately half of the thickness difference between the central portion and the edge portion of the electrode assembly (200). The thickness of the support portion (310) may correspond to half of the total thickness of the plurality of positive electrodes (210) included in the electrode assembly (200).

[0100] By the support portion (310) of the pad (300), the empty space within the receiving portion (110) caused by the relatively thin thickness of the edge portion of the electrode assembly (200) can be minimized, and problems such as lithium precipitation or electrode slippage that may occur in the electrode assembly (200) due to the empty space can be resolved.

[0101] Figure 9 is a plan view of the pad illustrated in Figure 7.

[0102] In order to correspond to the width (g1, g2) of the edge portion of the cathode (220) described above (see FIG. 6), the support portion (310) of the pad (300) may include a tab section (310a) and a side section (310b) having a narrower width than the tab section (310a).

[0103] The tab section (310a) may extend parallel to the side from which the negative electrode tab (220a) protrudes from the negative electrode (220). The side section (310b) may extend in a direction perpendicular to the tab section (310a). More specifically, the tab section (310a) may be provided in a pair parallel to the first side and the second side of the negative electrode (220). The side section (310b) may be provided in a pair parallel to the third side and the fourth side of the negative electrode (220).

[0104] Each tab section (310a) may overlap with the edge of the first side or the second side of the cathode (220) with respect to the stacking direction of the electrode assembly (200). Each side section (310b) may overlap with the edge of the third side or the fourth side of the cathode (220) with respect to the stacking direction of the electrode assembly (200).

[0105] The width (W21) of the tab section (310a) may be wider than the width (W22) of the side section (310b).

[0106] The width (W21) of the tab section (310a) may correspond to the width (g1) of the edge of the first or second side of the cathode (220) (see FIG. 6). The width (W22) of the side section (310b) may correspond to the width (g2) of the edge of the third or fourth side of the cathode (220).

[0107] For example, the width (W21) of the tab section (310a) may be 1 mm to 3 mm, and the width (W22) of the side section (310b) may be 1 mm to 2 mm. In addition, the width (W21) of the tab section (310a) may be 1 mm to 1.5 mm wider than the width (W22) of the side section (310b).

[0108] In this way, the peripheral area (113) of the receiving portion (110) can be optimized to match the shape of the edge of the electrode assembly (200), and the empty space within the receiving portion (110) can be minimized.

[0109] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0110] Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention but to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments.

[0111] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0112] [Explanation of symbols]

[0113] 10: Secondary battery 100: Battery case

[0114] 110: Receptacle 111: Bottom surface (of the receptacle)

[0115] 112: Main area 113: Perimeter area

[0116] 113a: Tap section 113b: Side section

[0117] 114: (Perimeter of the receiving area) 120: Terrace area

[0118] 200: Electrode assembly 210: Anode

[0119] 210a: positive tab 220: negative tab

[0120] 220a: Negative tab 230: Separator

[0121] 240: Positive lead 250: Negative lead

[0122] 300: Pad 310: Support

[0123] 310a: Tap section 310b: Side section

[0124] 320: Cover

Claims

1. A battery case including a receiving portion that receives an electrode assembly in which a positive electrode and a negative electrode are alternately laminated with a separator in between, and the edge of the negative electrode protrudes outward more than the positive electrode, The bottom surface of the above-mentioned receiving portion is Main area; and A battery case including a peripheral region positioned around the main region and having a predetermined step from the main region, and overlapping with an edge portion of the negative electrode with respect to the stacking direction of the electrode assembly.

2. In paragraph 1, Further comprising a terrace portion connected to the periphery of the above-mentioned receiving portion, A battery case in which the depth of the main area is deeper than the depth of the peripheral area based on the above terrace area.

3. In paragraph 1, The above-mentioned receiving portion includes a first receiving portion and a second receiving portion facing each other, The bottom surface of each of the first and second receiving portions is a battery case including the main region and the peripheral region.

4. In paragraph 1, The above-mentioned peripheral area is a battery case having a closed loop shape.

5. An electrode assembly in which positive and negative electrodes are alternately laminated with a separator between them, and the edge of the negative electrode protrudes outward more than the positive electrode; and A battery case having a receiving portion for receiving the electrode assembly, The bottom surface of the above-mentioned receiving portion is Main area; and A secondary battery comprising a peripheral region positioned around the main region, forming a predetermined step with the main region, and overlapping an edge portion of the negative electrode with respect to the stacking direction of the electrode assembly.

6. In paragraph 5, A secondary battery in which the width of the above peripheral area corresponds to the width of the edge of the negative electrode.

7. In paragraph 5, A secondary battery in which the step between the main region and the peripheral region corresponds to half of the total thickness of the positive electrode included in the electrode assembly.

8. In paragraph 5, The above perimeter area is, A tab section extending parallel to the side from which the cathode tab protrudes from the cathode; and A secondary battery including a side section extending in a direction perpendicular to the tab section and having a narrower width than the tab section.

9. An electrode assembly in which a positive electrode and a negative electrode are alternately laminated with a separator between them, and the edge of the negative electrode protrudes outward more than the positive electrode; A battery case having a receiving portion for receiving the electrode assembly; and Including a pad arranged on at least one side with respect to the stacking direction of the electrode assembly within the receiving portion, The above pad, A secondary battery comprising a support portion having a predetermined thickness and overlapping an edge portion of the negative electrode with respect to the stacking direction of the electrode assembly.

10. In paragraph 9, A secondary battery in which the width of the support portion corresponds to the width of the edge portion of the cathode.

11. In paragraph 9, The above support is a secondary battery having a closed loop shape.

12. In paragraph 9, A secondary battery in which the thickness of the support portion corresponds to the total thickness of the plurality of positive electrodes included in the electrode assembly.

13. In paragraph 9, The above pad, A secondary battery further comprising a cover portion positioned inside the support portion and having a thickness thinner than the support portion.

14. In paragraph 13, A secondary battery in which the difference between the thickness of the cover portion and the thickness of the support portion corresponds to the total thickness of the plurality of positive electrodes included in the electrode assembly.

15. In paragraph 9, The above pad is a secondary battery that is in close contact with the inner side of the bottom surface of the receiving portion.

16. In paragraph 9, The above-mentioned receiving portion includes a first receiving portion and a second receiving portion facing each other, The above pad, A first pad positioned on one side of the stacking direction of the electrode assembly and located within the first receiving portion; and A secondary battery including a second pad positioned on the other side with respect to the stacking direction of the electrode assembly and located within the second receiving portion.

17. In paragraph 9, The above support part, A tab section extending parallel to the side from which the cathode tab protrudes from the cathode; and A secondary battery including a side section extending in a direction perpendicular to the tab section and having a narrower width than the tab section.

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