Secondary battery

Abstract

In order to minimize an electrolyte pooling phenomenon due to electrode assembly expansion, a secondary battery may be provided, the battery comprising: an electrode assembly which includes a positive electrode, a negative electrode, and a separator interposed therebetween, is wound in one direction, and has formed a central hole; a case body having an accommodation space in which the electrode assembly and an electrolyte are accommodated; a cap assembly covering the case body; and an electrolyte absorber disposed in the central hole, wherein the electrolyte absorber is fixedly coupled to the cap assembly and is configured to absorb the flown-out electrolyte.

Description

secondary battery

[0001] Various embodiments of the present disclosure relate to secondary batteries.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0196265 dated December 24, 2024, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Secondary batteries are rechargeable and dischargeable, so they are widely used in mobile devices such as digital cameras, mobile phones, and laptops. In particular, demand for them is rapidly increasing as they are recently gaining attention as an energy source for electric vehicles and Energy Storage Systems (ESS).

[0004] Generally, secondary batteries can be classified according to the structure of the electrode assembly into a jelly-roll electrode assembly in which long sheet-type positive and negative electrodes are wound with a separator in between, a stack-type electrode assembly in which a plurality of positive and negative electrodes cut to a predetermined size are sequentially stacked with a separator in between, and a stack / folding-type electrode assembly in which bi-cells or full-cells, in which positive and negative electrodes cut to a predetermined size are stacked with a separator in between, are wound.

[0005] In addition, secondary batteries may be classified according to the shape of the case into cylindrical secondary batteries in which the electrode assembly is embedded in a cylindrical metal can, prismatic secondary batteries in which the electrode assembly is embedded in a prismatic metal can, and pouch-type secondary batteries in which the electrode assembly is embedded in a pouch-type case made of aluminum laminate sheet.

[0006] For example, in the case of a cylindrical secondary battery, a jelly-roll electrode assembly in which a positive electrode, a separator, and a negative electrode are wound integrally is housed in a cylindrical can along with an electrolyte. This structure can be manufactured by forming a sheet-shaped electrode (e.g., positive or negative electrode) by coating a composite material composed of an active material, a conductive material, and a binder onto a current collector in an unfolded state, and then winding this electrode sheet in one direction through a winding process to house it in a cylindrical can.

[0007] Meanwhile, the electrolyte, which is one of the key components of a secondary battery, can have a direct impact on the battery's charge / discharge performance and stability by enabling the movement of ions between the positive and negative electrodes.

[0008] However, during the charging of a secondary battery, the electrode assembly inside the case tends to increase in volume, and this increase in volume pressurizes the electrolyte. The pressurized electrolyte can leak into unintended areas within the case, causing various problems.

[0009] Particularly in the case of cylindrical cans, the pressurized electrolyte can extend beyond the longitudinal end region of the can and flow into the core, which is the empty space at the center in the width direction of the jelly-roll electrode assembly. Electrolyte flowing into these unintended areas can undergo a phase change into gas during high-temperature cycles, which can reduce the stability of the secondary battery and cause various problems, such as chemical corrosion on the inner wall of the case.

[0010] Various embodiments of the present disclosure are designed to solve at least some of the problems of the prior art as described above, and by minimizing the problem of electrolyte flowing into unintended areas within the case, it is possible to provide a secondary battery with minimized degradation and improved safety.

[0011] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by a person skilled in the art from the various embodiments of the present disclosure.

[0012] A secondary battery according to various embodiments of the present disclosure comprises an electrode assembly that is wound in one direction and forms a central hole, and includes a positive electrode, a negative electrode, and a separator interposed between them; a case body having a receiving space for accommodating the electrode assembly and an electrolyte; a cap assembly covering the case body; and an electrolyte absorber disposed in the central hole, wherein the electrolyte absorber may be configured to absorb an electrolyte that has leaked out by being fixedly coupled to the cap assembly.

[0013] For example, the secondary battery according to the present invention includes a positive electrode assembly that extends from the positive electrode and is connected to the cap assembly, and the positive electrode tab may have a structure that extends in a direction away from the center hole and is bent toward the center hole at one point.

[0014] For example, in the secondary battery according to the present invention, the cap assembly includes a current blocking device on the inside, and the electrolyte absorber can be fixed to the current blocking device.

[0015] For example, in the secondary battery according to the present invention, the electrolyte absorbent can be fixedly bonded to the cap assembly by an adhesive made of urethane material.

[0016] For example, in the secondary battery according to the present invention, the electrolyte absorbent may be formed of a mesoporous material.

[0017] For example, a secondary battery according to the present invention may include a beading portion formed in the case body to prevent the electrode assembly from detaching after the electrode assembly is accommodated in the receiving space, and the electrolyte absorber may be configured to absorb the electrolyte accumulating in the space between the beading portion of the case body and the cap assembly. For example, the beading portion may be formed at one end of the case body adjacent to the cap assembly, and the beading portion and the cap assembly may constitute the lower end of the secondary battery.

[0018] For example, in a secondary battery according to the present invention, the electrolyte absorbent may be configured such that it extends in the longitudinal direction of the electrode assembly from the central hole and has different porosity at one end and the other end.

[0019] For example, the diameters of one end and the other end of the electrolyte absorber may be different from each other.

[0020] For example, the above electrolyte absorbent may have a tapered shape in which the diameter gradually increases as it goes upward.

[0021] For example, the secondary battery according to the present invention may further include an electrolyte replenishing member disposed between the case body and the electrode assembly. For example, the electrolyte replenishing member may be configured to absorb the swelling pressure of the electrode assembly and break based on the swelling pressure to supply electrolyte to the electrode assembly.

[0022] For example, the secondary battery according to the present invention may have a closed-loop shape such that the electrolyte replenishing member is positioned adjacent to the cap assembly and at least partially surrounds the electrode assembly.

[0023] According to various embodiments of the present disclosure, a secondary battery with improved stability can be provided.

[0024] For example, a secondary battery according to various embodiments of the present disclosure can minimize various problems, such as chemical corrosion of the secondary battery due to the accumulation of electrolyte within the case.

[0025] FIG. 1 is a schematic exploded perspective view for explaining the structure of a secondary battery according to one embodiment of the present disclosure.

[0026] FIG. 2 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present disclosure.

[0027] FIG. 3 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present disclosure.

[0028] Figure 4 is a partial cutaway cross-sectional view of a secondary battery, showing an enlarged view of area A of Figure 2.

[0029] FIG. 5 is a schematic cross-sectional view illustrating a configuration in which a cap assembly is positioned downward in a secondary battery according to one embodiment of the present disclosure.

[0030] FIG. 6 is a schematic cross-sectional view illustrating a configuration in which a cap assembly is positioned downward in a secondary battery according to one embodiment of the present disclosure.

[0031] FIG. 7 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present disclosure.

[0032] Figure 8 schematically illustrates one form of an electrolyte replenishment member.

[0033] Embodiments of the present invention will be described below with reference to the attached drawings. However, the scope of the present invention is not limited to the embodiments presented. For example, a person skilled in the art who understands the scope of the present invention may propose other embodiments that fall within the scope of the concept of the present invention by adding, changing, or deleting components, and such embodiments shall also be deemed to be within the scope of the concept of the present invention. In the drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

[0034] In describing the embodiments, technical details that are well known in the technical field to which the present invention belongs and are not directly related to the present invention are omitted. This is intended to convey the essence of the present invention more clearly without obscuring it by omitting unnecessary explanations.

[0035] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference numbers.

[0036] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0037] Identical reference numbers or symbols in each drawing attached to this specification represent parts or components that perform substantially the same function. For convenience of explanation and understanding, the same reference numbers or symbols may be used to describe different embodiments. That is, even if components having the same reference number are depicted in multiple drawings, the multiple drawings do not all represent a single embodiment.

[0038] The terms used in the embodiments have been selected to be as widely used as possible, taking into account their functions in the present disclosure; however, these may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant explanatory section. Therefore, terms used in the present disclosure should be defined not merely by their names, but based on their meanings and the overall content of the present disclosure.

[0039] When a part of a specification is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as “...part” or “...module” as used in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware or software, or as a combination of hardware and software.

[0040] The expression “at least one of a, b, and c” described throughout the specification may include ‘a alone’, ‘b alone’, ‘c alone’, ‘a and b’, ‘a and c’, ‘b and c’, or ‘a, b, and c all’.

[0041] In addition, it should be noted in advance that expressions such as upper side, top, lower side, bottom, side, front, and rear in the following description are based on the direction depicted in the drawings, and may be expressed differently if the direction of the object changes.

[0042] Additionally, in this specification and claims, terms including ordinal numbers, such as "first," "second," etc., may be used to distinguish between components. These ordinal numbers are used to distinguish identical or similar components from one another, and the meaning of the terms should not be limited by the use of such ordinal numbers. For example, the order of use or arrangement of components combined with such ordinal numbers should not be limited by the number. If necessary, each ordinal number may be used interchangeably.

[0043] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor may appropriately define the concept of the terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the invention and do not represent all aspects of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0044] In this specification, the term "battery" may be used interchangeably with "secondary battery." Additionally, "battery" (or "secondary battery") may be understood as a collective term for the units thereof, such as battery cells, battery cell assemblies containing battery cells, battery modules, or battery packs.

[0045] In this specification, a battery module (or secondary battery module) is sufficient if it comprises a plurality of battery cells (or secondary battery cells) and is not limited to a specific shape, number, or stacking direction of the battery cells. For example, a battery module may include a battery cell assembly in which a plurality of battery cells are stacked. For example, a battery module may be understood as having a form in which the battery cells (or battery cell assembly) are housed in a module case to protect the battery cells from external impact.

[0046] FIG. 1 is a schematic exploded perspective view for explaining the structure of a secondary battery (1) according to one embodiment of the present disclosure.

[0047] The secondary battery (1) may include an electrode assembly (100) and a case (200) that accommodates the electrode assembly (100).

[0048] The electrode assembly (100) may include a plurality of electrodes (e.g., a first electrode (110), a second electrode (130)), an electrode tab (140) extending from at least some of the plurality of electrodes (110, 130), and a separator (120) interposed between the plurality of electrodes (110, 130).

[0049] For example, the electrode assembly (100) may have a structure in which a first electrode (110), a separator (120), and a second electrode (130) are sequentially stacked. For example, the electrode assembly (100) may have a structure in which a first electrode (110), a separator (120), a second electrode (130), and a separator (120) are sequentially stacked. For example, the first electrode (110) may be an anode and the second electrode (130) may be a cathode. Meanwhile, in one example, the outermost part of the electrode assembly (100) may be composed of a sealing tape to prevent the electrolyte impregnated in the electrode or separator from leaking out.

[0050] Each electrode (110, 130) of the electrode assembly (100) may have an active material layer coated on a sheet-shaped current collector. For example, the active material layer may be formed on at least one of a first surface (e.g., an inner surface facing the center hole (150) when wound) or a second surface facing in the opposite direction to the first surface (e.g., an outer surface facing away from the center hole (150) when wound) of the current collector configured in a sheet shape. Meanwhile, a portion of the current collector may include an uncoated portion where the active material layer is not coated.

[0051] For example, the first electrode (110) (e.g., positive electrode) can be formed by applying a composite material comprising at least an active material, a conductive material, and a binder to a current collector formed of a material such as an aluminum alloy. For example, the active material used in the first electrode (110) may include lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing one or more of these.

[0052] For example, the second electrode (130) (e.g., negative electrode) can be formed by applying a composite material comprising at least an active material, a conductive material, and a binder to a current collector formed of a material such as a copper alloy. For example, the active material used in the second electrode (130) may include a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, or tin or a tin compound.

[0053] In addition, in various embodiments of the present disclosure, materials such as active materials, conductive materials, and binders used for coating the electrodes (110, 130) may be various materials used in known secondary batteries.

[0054] The separator (120) can be placed between the electrodes (110, 130) to prevent electrical short circuits between the electrodes (110, 130) and can be configured to allow ions to pass through by impregnating an electrolyte. The separator (120) may include an insulating material. For example, the separator (120) may be formed of a porous polymer film or a porous nonwoven fabric. For example, the separator (120) may include a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., either alone or by laminating them. However, the separator included in the secondary battery according to various embodiments of the present disclosure is not necessarily limited to the above materials, and it goes without saying that various materials that can be conventionally applied in general secondary batteries may be used.

[0055] The electrode tab (140) is formed in a strip shape in a region of the end of each electrode (110, 130) (e.g., an uncoated region where the active material layer is not coated) and can be electrically connected to the electrode assembly (100) and the electrode terminal exposed to the outside. For example, the electrode tab (140) can be formed from aluminum (Al), copper (Cu), or lithium (Li) material.

[0056] The case (200) can form an internal space in which the electrode assembly (100) can be accommodated. For example, a jelly-roll type (wound type) electrode assembly (100) such as that shown in FIG. 1 may be accommodated in the internal space of a cylindrical case (200) by sequentially stacking a sheet-type first electrode (110), a separator (120), a second electrode (130), and a separator (120)) and then winding it in one direction (e.g., clockwise or counterclockwise) with respect to a central axis.

[0057] For example, the case (200) may include a case body (210) having an open end and a cap assembly (220) covering the open end of the case body (210).

[0058] The electrode assembly (100) can be received inside the case (200) through the open end of the case body (210). Once the electrode assembly (100) is received in the case (200), an electrolyte is injected into the inside of the case (200) so that the electrode assembly (100) is completely immersed, and a cap assembly (220) is attached to the open end of the case (200) to seal it, thereby forming a secondary battery (1).

[0059] The electrolyte can serve as a transport medium for ions (e.g., lithium ions (Li Ions)) generated by electrochemical reactions at the electrodes during the charging and discharging of a secondary battery. For example, the electrolyte may be a non-aqueous organic electrolyte, which is a mixture of a lithium salt and a high-purity organic solvent. In other examples, the electrolyte may be a polymer utilizing a polymeric electrolyte. In various embodiments, the electrolyte may be composed of other types of electrolyte materials other than those described above.

[0060] FIG. 2 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present disclosure. For example, FIG. 2 may be a conceptual cross-sectional view in the A-A' direction of FIG. 1.

[0061] Referring to FIG. 2, a secondary battery (1) according to one embodiment may be a cylindrical secondary battery, and an electrode assembly (100) received inside a cylindrical case (200, see FIG. 1) of the secondary battery (1) may be a jelly-roll electrode assembly in which a plurality of electrodes and a separator are wound in one direction. However, this is merely for convenience of explanation, and the present invention is not limited to a cylindrical secondary battery or a jelly-roll electrode assembly, and it is understood that the embodiments of the present disclosure may also be applied to secondary batteries or electrode assemblies having other structures or shapes within a range that is easily understood by a person skilled in the art.

[0062] As illustrated in FIG. 2, electrode tabs (140) may be formed protruding from each electrode (e.g., the first electrode (110) or the second electrode (130) of FIG. 1). For example, two electrode tabs (140) corresponding to each of the two electrodes having different polarities of the electrode assembly (100) (e.g., the first electrode (110), the second electrode (130)) may each be formed protruding in opposite directions within the case (200). However, the embodiments of the present disclosure are not limited to such bidirectional electrode tab structures, and it is also possible for the electrode tabs corresponding to each of the two electrodes having different polarities of the electrode assembly (100) to be configured to face in one direction (i.e., configured as a unidirectional electrode tab structure).

[0063] Meanwhile, each electrode tab (140) formed protruding from each electrode (110, 130) can be electrically connected to a current collector plate (160, 170). For example, in an embodiment, the first current collector plate (160) may be placed on one side in the longitudinal direction of the electrode assembly (100), and the second current collector plate (170) may be placed on the other side in the longitudinal direction of the electrode assembly (100).

[0064] For example, the first current collector plate (160) may be a negative current collector plate and the second current collector plate (170) may be a positive current collector plate. For example, the first current collector plate (160) may be connected to the negative electrode of the electrode assembly (100) to guide current to the negative terminal, and the second current collector plate (170) may be connected to the positive electrode to guide current to the positive terminal. On the other hand, it goes without saying that, depending on changes in the structure or design of the secondary battery (1), the first current collector plate (160) may be configured as a negative current collector plate and the second current collector plate (170) as a positive current collector plate.

[0065] The material of the current collector plate (160, 170) may include aluminum, copper, nickel, titanium, or stainless steel, but is not necessarily limited thereto, and metals and metal alloys commonly used as current collector materials may be adopted in the examples. For example, the positive current collector may be aluminum or an aluminum alloy, and the negative current collector may be copper or a copper alloy.

[0066] A central hole (150), which is an empty space, may be formed in the center of the electrode assembly (100) formed by the wound laminate. The central hole (150) may be used as an entry space for a welding rod for welding the electrode assembly (100) and the case body (210). Additionally, the central hole (150) may be used as an inlet for injecting an electrolyte.

[0067] The secondary battery (1) can be manufactured by sealing it with a cap assembly (220) after the electrolyte is injected. The electrode assembly (100) can expand during charging of the secondary battery (1) and contract during discharging. When the electrode assembly (100) expands, the electrolyte impregnated in the electrode assembly (100) may leak out accordingly. This phenomenon is also referred to as the electrolyte squeezed-out phenomenon.

[0068] The electrolyte leaked due to the electrolyte accumulation phenomenon may be converted into a gas by the high-temperature cycle of the secondary battery (1), which can reduce the stability of the secondary battery (1) and cause various reliability problems, such as chemical corrosion of the case (200) as it remains in a specific space within the case (200). To prevent such problems, the secondary battery (1) according to various embodiments of the present disclosure may include an electrolyte absorber (310).

[0069] For example, the electrolyte absorber (310) is placed in the central hole (150) formed by the electrode assembly (100) and can absorb the electrolyte leaked out by the expansion of the electrode assembly (100).

[0070] For example, the electrolyte absorber (310) may include a porous material. For example, the electrolyte absorber (310) may include a porous polymer material.

[0071] For example, the electrolyte absorber may include a mesoporous material. The electrolyte absorber (310) including the mesoporous material has a light weight characteristic, which can satisfy the lightweight requirements required for the secondary battery (1). For example, the mesoporous material may have buffering properties, and accordingly, the electrolyte absorber (310) may prevent the risk of damaging the electrode assembly (100) and may function to absorb the swelling pressure of the electrode assembly (100).

[0072] For example, the electrolyte absorber (310) may include a porous paper material. As a more specific example, the electrolyte absorber (310) may include porous alumina-silica paper, thereby minimizing the possibility of explosion of the secondary battery (1) through high heat resistance and excellent insulation properties, and minimizing flame and heat transfer in the event of an explosion.

[0073] According to various embodiments, the electrolyte absorbent (310) may have a pipe shape penetrating the center hole (150).

[0074] The diameter D1 of the electrolyte absorbent may be, for example, 2 mm or around that.

[0075] The diameter D1 of the electrolyte absorber (310) can be appropriately designed to correspond to the diameter D2 of the center hole (150). For example, the electrolyte absorber (310) may have a diameter D1 smaller than the diameter D2 of the center hole (150) so that when the electrolyte absorber (310) is placed in the center hole (150), a predetermined gap is formed between it and the inner surface of the electrode assembly (100). This gap can minimize the possibility of damage to either side caused by interference between the two members when the electrode assembly (100) or the electrolyte absorber (310) expands.

[0076] FIG. 3 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present disclosure. For example, FIG. 3 may correspond to a conceptual cross-sectional view in the A-A' direction of the secondary battery (1) shown in FIG. 1.

[0077] Unlike what was described with reference to FIG. 2, an electrolyte absorber (310) according to one embodiment may be provided with a diameter (D1, D2) equal to that of the center hole (150) so that no empty space is formed in the lateral direction of the center hole (150) of the electrode assembly (100). That is, the diameter D1 of the electrolyte absorber (310) and the diameter D2 of the center hole (150) may be configured to be substantially the same.

[0078] In this case, based on the transverse direction, the center hole (150) is filled by the electrolyte absorber (310), so that the electrode assembly (100) supports the electrolyte absorber (310) from one another, thereby minimizing flow between the two members (100, 310) and further preventing damage or short circuit of the electrode assembly (100) caused by repeated collisions between the two members (100, 310).

[0079] Figure 4 is a partial cutaway cross-sectional view of a secondary battery, showing an enlarged view of area A of Figure 2.

[0080] Referring to FIG. 4, in a secondary battery (1) according to various embodiments, an electrolyte absorber (310) may be coupled to a part of a case (200, FIG. 1). For example, the electrolyte absorber (310) may be fixedly coupled to a cap assembly (220) that covers one end of a case body (210).

[0081] For example, the electrolyte absorber (310) disposed in the center hole (150) of the electrode assembly (100) may have a pipe shape extending along the longitudinal direction of the center hole (150) and may be coupled to one area of ​​the inner surface of the cap assembly (220).

[0082] More specifically, an electrolyte absorbent (310) according to one embodiment may be coupled to a current interrupt device (CID, 180) provided on the inner surface of a cap assembly (220) at one end in the longitudinal direction. The current interrupt device (180) may have a structure capable of interrupting the circuit of the secondary battery (1) in the event of overcharging or overcurrent. For example, the current interrupt device (180) may serve to interrupt the circuit of the secondary battery (1) when the internal pressure of the secondary battery (1) rises abnormally or the temperature rises rapidly.

[0083] In the example, the electrolyte absorber (310) and the current blocking device (180) can be bonded and fixed by an adhesive (320).

[0084] For example, the adhesive (320) may include a urethane material. The urethane adhesive (320) ensures sufficient adhesion while minimizing the possibility of unintended chemical reactions occurring in the secondary battery (1) by not generating by-products during the reaction.

[0085] Meanwhile, the electrolyte absorber (310) can be fixed by being bonded to the inner center area of ​​the current blocking device (180).

[0086] For example, the inner surface center region of the current blocking device (180) according to one embodiment may include an area that is recessed outwardly (e.g., the recessed portion (181) of FIG. 4), and the electrolyte absorber (310) may have a shape that fits into this recessed shape of the current blocking device (180) and may be seated and fixed in the recessed area of ​​the current blocking device (180).

[0087] For example, the diameter of the recess (181) of the current blocking device (180) may correspond to the diameter (D1, FIG. 2) of the electrolyte absorber (310). The diameter of the recess (181) may be equal to or slightly larger than the diameter (D1) of the electrolyte absorber (310). In some cases, the lateral gap between the electrolyte absorber (310) and the recess (181) may be filled with an adhesive (320). Such a joining shape between the recess (181) of the current blocking device (180) and the electrolyte absorber (310) can maximize the face-to-face area between the current blocking device (180) and the electrolyte absorber (310), thereby strengthening the fixing force between the two members (180, 310).

[0088] Meanwhile, according to various embodiments, the anode tab (140) extending from the anode and connected to the cap assembly (220) may have an avoidance structure so as not to interfere with the electrolyte absorber (310).

[0089] For example, according to one embodiment, the anode tab (140) may be extended in a direction away from the center hole (150), then bent in a direction closer to the center hole (150) at one point and electrically connected to the cap assembly (220). With this structure, the anode tab (140) may not come into contact with the electrolyte absorber (310) which is placed in the center hole (150) and fixedly coupled to the center of the cap assembly (220).

[0090] As another example, unlike that illustrated in FIG. 4, the positive electrode tab (140) according to one embodiment may have an avoidance shape that is not bent at one point but is bent overall so as not to interfere with the electrolyte absorber (310) which is formed extending along the length direction from the center hole (150).

[0091] FIG. 5 is a cross-sectional view schematically illustrating a configuration in which a cap assembly (220) is positioned downward in a secondary battery according to one embodiment of the present disclosure. For example, FIG. 5 may correspond to a secondary battery (1) according to an embodiment described with reference to FIG. 2. The description of the present embodiment may be applied in the same manner to the extent that it does not contradict the features of other embodiments.

[0092] Referring to FIG. 5, the beading portion (230) may be positioned on one side of the case body (210) where the cap assembly (220) is placed (e.g., the bottom of the secondary battery (1) in FIG. 5).

[0093] The beading portion (230) may have a shape that is recessed toward the center of the secondary battery (1) by a predetermined depth in a region along a certain height perimeter of the case body (210). The beading portion (230) may be manufactured by folding or bending a plate constituting the case body (210).

[0094] The beading portion (230) can secure sealing of at least one area of ​​the internal space of the secondary battery (1) and reinforce the mechanical strength of the case body (210).

[0095] For example, the beading portion (230) can prevent the electrode assembly (100) housed inside the case body (210) from shaking in the internal clearance space or moving outward from the beading portion (230). The beading portion (230) contributes to the easy positional alignment of the cap assembly (220) on the case body (210) and can subsequently allow the cap assembly (220) to be fixed to the case body (210). Furthermore, the beading portion (230) can also perform the functions of preventing internal gas leakage and dispersing pressure.

[0096] Meanwhile, the cap assembly (220) may include a vent portion provided to allow venting gas to be discharged in situations where venting is required. For example, the cap assembly (220) may be provided with a notch portion (not shown) as a vent portion that induces the discharge of venting gas by breaking when the internal pressure of the secondary battery (1) exceeds a reference size.

[0097] In the embodiment, the downward placement of the cap assembly (220) and the beading part (230) allows heat and pressure to be dissipated downward as much as possible in the event of a thermal event such as an explosion in the secondary battery (1), thereby minimizing the risk of various problems caused by the explosion being transmitted to the cabin room of the vehicle.

[0098] On the other hand, the downward arrangement of the cap assembly (220) and the beading portion (230) can cause a problem in which the electrolyte leaks out from the electrode assembly (100) during the charging and discharging process of the secondary battery (1) and is not reabsorbed into the electrode assembly (100), but gradually accumulates in the area below the beading portion (230). Accordingly, the electrolyte accumulated in the area below the beading portion (230) can cause problems such as chemically corroding the case body (210) or damaging the cap assembly (220).

[0099] According to an embodiment of the present disclosure, as the electrolyte absorber (310) is provided to be in contact with the cap assembly (220), the electrolyte accumulated in the area below the beading portion (230) in the internal space can be easily absorbed.

[0100] According to one embodiment, in order to minimize the accumulation of electrolyte in the area below the beading portion (230) within the internal space of the secondary battery (1), the electrolyte absorber (310) may have a structure that allows it to move upward more effectively when absorbing electrolyte.

[0101] For example, in configuring an electrolyte absorber (310) containing a mesoporous material, the porosity may be configured to increase as it moves further away from the cap assembly (220), that is, as it moves upward from the electrolyte absorber (310). For example, the size of the pores in the region of the electrolyte absorber (310) far from the cap assembly (220) may be larger than the size of the pores in the region relatively close to it.

[0102] According to another embodiment, the electrolyte absorber (310) may have a pore density in a region far from the cap assembly (220) that is greater than the pore density in a region relatively close to it. Through this configuration, the electrolyte absorber (310) can further promote capillary action to prevent the electrolyte from accumulating at the bottom of the secondary battery (1).

[0103] Unlike the above embodiments, the electrolyte absorber (310) may have a uniform porosity over the entire area. That is, the electrolyte absorber (310) may have the same or similar pore size and density over the entire area.

[0104] FIG. 6 illustrates a secondary battery (1) of another embodiment in which the cap assembly (220) is positioned so as to face downward.

[0105] According to one embodiment, as a method to make the upper region porosity of the electrolyte absorber (310) greater than the lower region porosity, the electrolyte absorber (310) may be provided with a tapered shape in which the diameter gradually increases as it goes upward.

[0106] For example, in order to maximize the absorption capacity of the electrolyte absorber (310) and minimize the phenomenon of the electrolyte accumulating in the lower part of the internal space of the secondary battery (1) through capillary action, the other end of the electrolyte absorber (310) may extend to the top of the secondary battery (1). For example, the other end of the electrolyte absorber (310), that is, the top, may be provided to be in contact with the first current collector plate (160).

[0107] FIG. 7 is a partial cutaway cross-sectional view of a secondary battery (1) according to another embodiment. For example, FIG. 7 is a conceptual cross-sectional view in the A-A' direction of FIG. 1. FIG. 8 is a schematic illustration of one form of an electrolyte replenishing member (410).

[0108] Referring to FIGS. 7 and 8, a secondary battery (1) according to one embodiment may include an electrolyte absorber (310) for absorbing an electrolyte that has accumulated around a case after coming out of an electrode assembly (100) during use (i.e., charging and discharging) and an electrolyte replenishing member (410) for additionally supplying an electrolyte that has become insufficient in the electrode assembly (100).

[0109] For example, the electrolyte replenishment member (410) may be positioned between the electrode assembly (100) and the case (200) (e.g., case body (210)). For example, the electrolyte replenishment member (410) may have a capsule shape capable of containing electrolyte in its internal space (411).

[0110] The electrolyte (e.g., second electrolyte) contained in the internal space (411) of the electrolyte replenishment member (410) may be physically separated from the electrolyte (e.g., first electrolyte) injected to impregnate the electrode assembly (100). At this time, the second electrolyte contained in the electrolyte replenishment member (410) may be of the same or different material as the first electrolyte already impregnated in the electrode assembly (100).

[0111] In the embodiment, the electrolyte replenishment member (410) may be formed of a material capable of absorbing the swelling pressure of the electrode assembly (100). For example, the electrolyte replenishment member (410) may be composed of a material with elasticity. For example, the electrolyte replenishment member (410) may be broken when a swelling pressure exceeding a predetermined size is applied, and upon the breakage of the electrolyte replenishment member (410), the electrolyte (e.g., second electrolyte) contained in the internal space may be discharged to the outside of the electrolyte replenishment member (410) and flow toward the electrode assembly (100).

[0112] Meanwhile, in the embodiment, the electrolyte replenishment member (410) may be positioned adjacent to one end of the electrode assembly (100) so that the second electrolyte discharged upon breakage can penetrate the electrode assembly (100) more effectively. For example, the electrolyte replenishment member (410) may be positioned adjacent to the cap assembly (220) between the case body (210) and the electrode assembly (100). In this case, as a separate member (e.g., sealing tape) is additionally provided at the outermost end of the electrode assembly (100), the second electrolyte from the electrolyte replenishment member (410) can be impregnated through one end in the longitudinal direction of the electrode assembly (100) even in a structure where the second electrolyte cannot be directly impregnated through the side portion of the electrode assembly (100). Furthermore, according to one embodiment, the electrolyte replenishing member (410) may be positioned to surround the electrode assembly (100) at one end in the longitudinal direction of the electrode assembly (100) (e.g., the periphery of the cap assembly (220)), and accordingly, damage to the case (200) may be minimized by absorbing swelling pressure in a specific area of ​​the case body (210) that is prone to damage due to swelling pressure (e.g., the area of ​​the beading portion (230) of the case body (210) that is beaded inwardly at a location adjacent to the cap assembly (220)).

[0113] Meanwhile, in the embodiment, the electrolyte replenishment member (410) may have a closed-loop shape overall. For example, the electrolyte replenishment member (410) may be ring-shaped (e.g., circular ring, square ring, elliptical ring, etc.). Accordingly, the electrolyte replenishment member (410) can effectively absorb the swelling pressure of the electrode assembly (100) regardless of the direction in which the swelling pressure of the electrode assembly (100) is applied toward the case (200), that is, regardless of the direction of swelling.

[0114] For example, in a cylindrical (or elliptical or polygonal prism) electrode assembly (100), the swelling pressure acts most strongly in the direction from the inner circumference side of the electrode assembly (100) toward the outer circumference side, and acts only relatively small in the direction from the outer circumference side of the electrode assembly (100) toward the inner circumference side or from the center side of the electrode assembly (100) toward both ends in the longitudinal direction.

[0115] Accordingly, in the comparative example, the electrolyte replenishment member (410) may be inserted into the center hole (150) of the electrode assembly (100) or interposed between the end of the case (200) (e.g., cap assembly (220)) and the adjacent end of the electrode assembly (100). However, in the case of such a comparative example, the swelling pressure applied to the electrolyte replenishment member (410) may not be sufficient to cause the electrolyte replenishment member (410) to break, and thus the electrolyte replenishment member (410) may not break at the required time, thereby failing to provide the effect according to the embodiments of the present invention of supplying insufficient electrolyte to the electrode assembly (100). Furthermore, as the electrolyte replenishment member (410) is positioned between the case body (210) and the electrode assembly (100), the effect of protecting vulnerable points of the case (200) from swelling of the electrode assembly (100) may also not be obtained.

[0116] The electrolyte replenishment member (410) can be formed to an appropriate size that can be interposed between the case (200) and the electrode assembly (100). For example, the outer diameter (300D1) of the electrolyte replenishment member (410) can be configured to a size corresponding to the inner diameter of the case (200) so that it can be positioned inside the case (200). Additionally, the inner diameter (300D2) of the electrolyte replenishment member (410) can be configured to a size corresponding to the outer diameter of the electrode assembly (100) in a corresponding area so that the electrolyte replenishment member (410) can surround the outer edge of the electrode assembly (100).

[0117] In one example, the electrolyte replenishment member (410) may be attached to the inner surface of the case body (210) before the electrode assembly (100) is received in the case (200). For instance, the electrode assembly (100) may be inserted into the internal space of the case (200) in which the electrolyte replenishment member (410) is mounted on the inner surface. In this process, for smoother assembly, the outer diameter of the electrode assembly (100) may be configured to be smaller than the inner diameter (300D2) of the electrolyte replenishment member (410).

[0118] Meanwhile, the present specification and drawings disclose preferred embodiments of the present invention. Although specific terms have been used, they are used merely in a general sense to facilitate the explanation of the technical content of the present invention and to aid in understanding the invention, and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that, in addition to the embodiments disclosed herein, other variations based on the technical concept of the present invention are possible.

[0119] The aforementioned embodiments are merely examples, and other embodiments may be implemented within the scope of the claims set forth below.

Claims

1. An electrode assembly comprising an anode, a cathode, and a separator interposed between them, wound in one direction and forming a central hole; A case body having a receiving space for accommodating the electrode assembly and electrolyte, and a cap assembly covering the case body; and It includes an electrolyte absorbent disposed in the above-mentioned central hole, and The above electrolyte absorbent is, A secondary battery configured to absorb the leaked electrolyte by being fixedly coupled to the above-mentioned cap assembly.

2. In Paragraph 1, The electrode assembly includes an anode tab that extends from the anode and is connected to the cap assembly, and A secondary battery, wherein the positive electrode tab extends in a direction away from the center hole and is bent toward the center hole at one point.

3. In Paragraph 1, The above cap assembly includes a current blocking device on the inside, and A secondary battery in which the above electrolyte absorbent extends in the longitudinal direction of the electrode assembly from the center hole and is fixed to the current blocking device.

4. In Paragraph 1, A secondary battery in which the above electrolyte absorbent is fixedly bonded to the above cap assembly by a urethane adhesive.

5. In Paragraph 1, The above electrolyte absorber comprises a mesoporous material, in a secondary battery.

6. In Paragraph 1, The above case body is, It includes a beading portion formed to prevent the electrode assembly from detaching after the electrode assembly is received in the receiving space, The above electrolyte absorbent is, A secondary battery configured to absorb an electrolyte that accumulates in the space between the beading portion of the case body and the cap assembly.

7. In Paragraph 6, The above beading portion is formed at one end of the case body adjacent to the cap assembly, and A secondary battery in which the above beading portion and the above cap assembly constitute the lower part of the secondary battery.

8. In Paragraph 1, The above electrolyte absorbent is, A secondary battery extending in the longitudinal direction of the electrode assembly from the above-mentioned central hole, configured such that the porosity of one end and the other end are different.

9. In Paragraph 1, The above electrolyte absorbent is, A secondary battery in which the diameters of one end and the other end are different from each other.

10. In Paragraph 9, The above electrolyte absorbent is, A secondary battery having a tapered shape in which the diameter gradually increases toward the top.

11. In Paragraph 1, A secondary battery further comprising an electrolyte replenishing member disposed between the case body and the electrode assembly, which absorbs swelling pressure of the electrode assembly and breaks based on the swelling pressure to supply electrolyte to the electrode assembly.

12. In Paragraph 11, A secondary battery in which the electrolyte replenishing member is positioned adjacent to the cap assembly and has a closed-loop shape to at least partially surround the electrode assembly.

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