Improved safety of rectangular secondary batteries

Abstract

The disclosed invention relates to a rectangular secondary battery, and in one example, includes a case at least one side of which forms an open surface, an electrode assembly housed inside the case via the open surface of the case, and a cap plate which is coupled to the open surface of the case to seal it and has positive and negative electrode terminals, wherein a swelling tape which stretches or expands upon contact with an electrolyte filled in the case is attached to a surface of the electrode assembly, and a first concave beading processing portion is formed on at least two opposing surfaces along the front, rear, left and right edges of the case.

Description

[Technical field]

[0001] The present invention relates to a prismatic secondary battery having improved safety by preventing internal shaking of an electrode assembly.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0100399 dated August 11, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. [Background technology]

[0003] Unlike primary batteries, secondary batteries can be recharged, and they have been much researched and developed in recent years due to their potential for miniaturization and large capacity. The demand for secondary batteries as an energy source is rapidly increasing due to the increasing technological development and demand for mobile devices, as well as the emergence of electric vehicles and energy storage systems in response to the modern demand for environmental protection.

[0004] Secondary batteries are classified into coin type batteries, cylindrical type batteries, square type batteries, and pouch type batteries according to the shape of the battery case. The electrode assembly installed inside the battery case of the secondary battery is a power generating element capable of charging and discharging, which is made of a laminated structure of electrodes and a separator.

[0005] Electrode assemblies can be broadly classified into a jellyroll type in which a sheet-like positive electrode and negative electrode coated with an active material are wound with a separator interposed between them; a stack type in which a number of positive electrodes and negative electrodes are sequentially stacked with a separator interposed between them; and a stack & folding type in which a stack type unit cell is wound with a long separator film.

[0006] The positive and negative tabs of the electrode assembly housed in the prismatic secondary battery are joined to electrode leads, respectively, and then connected to the positive and negative terminals on the case. The case housing the electrode assembly has some extra space for electrical connection of the electrode assembly and for the amount of electrolyte required to be poured. Therefore, the electrode assembly inside the case may experience a rocking or slipping phenomenon due to external shock. In particular, the rocking phenomenon frequently occurs in prismatic secondary batteries used in hybrid and electric vehicles due to shocks while driving.

[0007] The structural support of the electrode assembly is mainly provided by the positive and negative tabs (electrode tabs) connected to the positive and negative terminals. Therefore, if the electrode assembly is rocked, various problems may occur, such as stress being concentrated on the electrode tabs, causing the tabs to break, or a short circuit due to electrical contact. In addition, damage to the tabs may reduce the capacity of the secondary battery or cause imbalance between the multiple batteries housed in the battery pack, resulting in various safety issues that shorten the lifespan of the batteries. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 2014-0017743 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to improve the support structure of an electrode assembly housed inside a prismatic secondary battery, thereby making it possible to suppress shaking during use.

[0010] However, the technical problem that the present invention aims to solve is not limited to the above-mentioned problem, and other problems not mentioned can be clearly understood by a person skilled in the art from the description of the invention described below. [Means for solving the problem]

[0011] The present invention relates to a prismatic secondary battery, in one example, comprising: a case at least one side of which forms an open surface; an electrode assembly housed inside the case via the open surface of the case; and a cap plate coupled to the open surface of the case to seal the open surface and having positive and negative electrode terminals. A swelling tape that expands or stretches upon contact with an electrolyte filled in the case is attached to a surface of the electrode assembly, and a first concave beading portion is formed on at least two opposing surfaces along the front, rear, left and right edges of the case.

[0012] The swelling tape stretches or expands in volume longitudinally upon contact with the electrolyte.

[0013] The swelling tape may be attached to the front, rear, left and right surfaces of the electrode assembly.

[0014] In an embodiment of the present invention, the swelling tape may be continuously attached along the edges of the front, rear, left and right sides of the electrode assembly.

[0015] Alternatively, the swelling tape may be attached along the edges of the front, rear, left and right sides of the electrode assembly, and may form a first gap along the entire edge between the front, rear, left and right sides of the electrode assembly.

[0016] Furthermore, the swelling tape may form a second gap in the center of the front and rear surfaces of the electrode assembly.

[0017] Here, the swelling tape attached to the front and rear surfaces of the electrode assembly may be cut off at both sides by the second blank portion.

[0018] In addition, the swelling tape may form third blank portions at the center of the left and right sides of the electrode assembly.

[0019] Meanwhile, in an embodiment of the present invention, the first beading processing portion presses a surface of the swelling tape attached to the electrode assembly housed inside the case.

[0020] The first beading processing portion may be formed at a position spaced apart from an electrode tab of the electrode assembly housed inside the case, and may be formed adjacent to the cap plate so as to press against an upper portion of the electrode assembly housed inside the case.

[0021] The first beading processed portion may be formed continuously over four surfaces along the front, rear, left and right edges of the case.

[0022] The case may further include second beading processed portions formed on at least two opposing surfaces along the front, rear, left and right edges at a height adjacent to the bottom surface of the case.

[0023] The second beading processing portion supports a lower portion of the electrode assembly housed inside the case.

[0024] In an embodiment of the present invention, the second beading processing portion may contact and support a bottom surface of the electrode assembly. Effect of the Invention

[0025] In the prismatic secondary battery of the present invention having the above-mentioned configuration, the swelling tape, which expands or stretches upon contact with the electrolyte filled in the case, is attached to the front, rear, left and right sides of the electrode assembly, and the swelling tape, which has come into contact with the electrolyte, fills the gap between the inner surface of the case and the electrode assembly, thereby suppressing the oscillation of the electrode assembly in the front, rear and left and right directions.

[0026] In addition, in the prismatic secondary battery of the present invention, the concave beading portion formed on the case presses and fixes the electrode assembly via the swelling tape, thereby improving the support structure of the electrode assembly.

[0027] Therefore, the prismatic secondary battery of the present invention suppresses the front-rear and left-right shaking of the electrode assembly and improves the overall support structure, thereby preventing various problems such as short circuit due to electrical contact caused by the shaking phenomenon during use and breakage of tabs, and thus significantly improving the safety of the secondary battery.

[0028] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned can be clearly understood by those of ordinary skill in the art from the description of the invention described below.

[0029] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. [Brief description of the drawings]

[0030] [Figure 1] 1 is an exploded perspective view of a prismatic secondary battery according to an embodiment of the present invention; [Diagram 2] 1 is a perspective view illustrating an attachment structure of a swelling tape according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a perspective view illustrating an attachment structure of a swelling tape having a first blank portion. [Figure 4] 11A to 11C are perspective views illustrating attachment structures of a swelling tape having a second blank portion. [Diagram 5] 11A to 11C are perspective views illustrating attachment structures of a swelling tape having a second blank portion. [Figure 6] FIG. 13 is a perspective view illustrating an attachment structure of a swelling tape having a third blank portion. [Figure 7] 4 is a cross-sectional view illustrating a structure in which a first beading processing portion supports an electrode assembly. [Figure 8] 11 is a view illustrating a relative position between a first beading processing portion and an electrode assembly. [Figure 9]FIG. 13 is a perspective view illustrating an embodiment including a first beading processing portion and a second beading processing portion. [Figure 10] 4 is a cross-sectional view illustrating a structure in which a first beading processing portion and a second beading processing portion support an electrode assembly. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0032] However, this is not intended to limit the invention to any particular embodiment, but it should be understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0033] In the present invention, terms such as "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and may be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0034] In addition, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion in between. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion in between. In addition, in the present application, being "on" can include not only the case where it is located at the top, but also the case where it is located at the bottom.

[0035] The present invention relates to a prismatic secondary battery, in one example, including a case having at least one side forming an open surface, an electrode assembly housed inside the case via the open surface of the case, and a cap plate coupled to the open surface of the case to seal the open surface, and having positive and negative electrode terminals.

[0036] Here, in the prismatic secondary battery of the present invention, a swelling tape that expands or contracts upon contact with the electrolyte filled in the case is attached to the surface of the electrode assembly.

[0037] Here, the swelling tape may be one that elongates in the longitudinal direction upon contact with the electrolyte, or one that expands in volume upon contact with the electrolyte.

[0038] A first concave beading processed portion is formed on at least two opposing surfaces along the front, rear, left and right edges of the case.

[0039] Here, the first beading processed portion formed in a concave shape toward the inside of the case presses the surface of the swelling tape attached to the electrode assembly housed inside the case.

[0040] In the prismatic secondary battery of the present invention having such a configuration, swelling tapes that expand or elongate upon contact with the electrolyte filled in the case are attached to the front, rear, left and right sides of the electrode assembly, and the swelling tapes that come into contact with the electrolyte fill the gap between the inner surface of the case and the electrode assembly, thereby suppressing rocking of the electrode assembly in the front, rear, left and right directions.

[0041] In addition, in the prismatic secondary battery of the present invention, the concave beading processing portion formed on the case indirectly presses and fixes the surface of the electrode assembly via the swelling tape, improving the support structure of the electrode assembly and suppressing slippage during use, thereby preventing various problems such as short circuits due to electrical contact and broken tabs, thereby significantly improving the safety of the secondary battery.

[0042] In addition, since the beading process does not directly press the surface of the electrode assembly, even if slight friction occurs on the beading process, the swelling tape buffers it, greatly reducing the risk of damage to the electrode assembly.

[0043] Therefore, in the prismatic secondary battery of the present invention, the electrode assembly is prevented from shaking in the front, back, left and right directions, and the support structure is improved, thereby preventing various problems such as short circuits due to electrical contact caused by the shaking phenomenon during use and breakage of tabs, etc. As a result, the safety of the secondary battery is significantly improved.

[0044] Hereinafter, a detailed description will be given of a specific embodiment of a prismatic secondary battery according to the present invention with reference to the accompanying drawings. For reference, the directions of front, back, up, down, left and right used in the following description are intended to facilitate understanding of the invention, and unless otherwise specified, the directions are based on the directions shown in the drawings.

[0045] (First embodiment) FIG. 1 is an exploded perspective view of a prismatic secondary battery 10 according to one embodiment of the present invention.

[0046] The illustrated prismatic secondary battery 10 includes a case 100 having at least one open surface, and an electrode assembly 300 including a plurality of stacked unit cells is housed inside the case 100 through the open surface of the case 100. A cap plate 200 including positive and negative electrode terminals 210 is coupled to the case 100 to seal the open surface.

[0047] The prismatic secondary battery 10 of the first embodiment shown in FIG. 1 is a one-way secondary battery in which positive and negative electrode terminals 210 are both disposed on the top surface of a case 100, and the top surface of the case 100 is an open surface, so that a cap plate 200 seals the top surface of the case 100.

[0048] The electrode assembly 300 in which the unit cells are stacked is sealed and housed in the case 100. A unit cell is a cell having a unit structure of anode / separator / cathode, and a plurality of unit cells are stacked to form one electrode assembly 300. The general structure of a unit cell is as follows.

[0049] The positive electrode includes a positive electrode current collector and a positive electrode active material applied to one or both sides of the positive electrode current collector. At one end of the width direction of the positive electrode current collector, there is a plain portion where the positive electrode active material is not applied. The plain portion is notched (punched) to form a positive electrode tab 312.

[0050] The negative electrode includes a negative electrode current collector and a negative electrode active material applied to one or both sides of the negative electrode current collector. At one end of the width direction of the negative electrode current collector, there is a non-coated portion where the negative electrode active material is not applied. Similarly, the non-coated portion of the negative electrode functions as a negative electrode tab 314.

[0051] In the first embodiment, the electrode tabs 310, i.e., the positive electrode tab 312 and the negative electrode tab 314, are located at the same end along the width direction of the electrode assembly 300, i.e., along the height direction of the prismatic secondary battery 10. In the illustrated example, the positive electrode tab 312 and the negative electrode tab 314 extend toward the upper surface of the prismatic secondary battery 10, and the positive electrode tab 312 and the negative electrode tab 314 are electrically connected to a positive electrode terminal and a negative electrode terminal provided on the cap plate 200, respectively.

[0052] In the present invention, the positive electrode active material coated on the positive electrode current collector and the negative electrode active material coated on the negative electrode current collector may be any active material known in the art without any limitations.

[0053] In one example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z(A includes at least one element selected from Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Ti, Si, Fe, V, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, 0.1≦z≦2; x, y, z, and the stoichiometric coefficients of the components in M ​​are selected such that the compound remains electrically neutral).

[0054] In another example, the positive electrode active material is an alkali metal compound xLiM disclosed in US Pat. No. 6,677,082, US Pat. No. 6,680,143, etc. 1 O2(1x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 x may be 0≦x≦1).

[0055] In another example, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1x M 2 y P 1y M 3 z O 4z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, Al, As, Sb, Si, Ge, V and S; M 3 contains halogen elements, optionally including F; <a≦2、0≦x≦1、0≦y<1、0≦z<1;a、x、y、z、M 1 , M 2 and M. 3wherein the stoichiometric coefficients of the components are selected such that the compound maintains electrical neutrality), or lithium metal phosphate, represented by Li3M2(PO4)3, where M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Mg, and Al.

[0056] Preferably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0057] In one example, the negative electrode active material may be a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. Metal oxides such as TiO2 and SnO2 having a potential of less than 2 V may also be used as the negative electrode active material. As the carbon material, low-crystalline carbon, high-crystalline carbon, etc. may both be used.

[0058] The separator interposed between the positive electrode and the negative electrode may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., or may be a laminate of these. As another example, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric such as a high melting point glass fiber or a polyethylene terephthalate fiber.

[0059] At least one surface of the separator may include a coating layer of inorganic particles. The separator itself may also be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder such that there is an interstitial volume between adjacent particles.

[0060] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O3 (PZT), Pb 1x La x Zr1y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3PbTiO3 (PMNPT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0061] The electrolyte that constitutes the electrolyte solution 400 in which the electrode assembly 300 is impregnated is A + B - In this case, the salt may have the structure: + Li + , Na + , K + and ions consisting of combinations of these. - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C -, CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The anion comprises one or more anions selected from the group consisting of:

[0062] The electrolyte may also be dissolved in an organic solvent, such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone, or a mixture thereof.

[0063] Returning to FIG. 1, the prismatic secondary battery 10 of the present invention includes a swelling tape 500 attached to the surface of the electrode assembly 300. The swelling tape 500 has a property of stretching or expanding upon contact with the electrolyte 400 filled in the case 100. That is, the swelling tape 500 has a property of stretching in the longitudinal direction or volumetrically expanding upon contact with the electrolyte 400.

[0064] There is some marginal space between the electrode assembly 300 and the case 100, taking into consideration the ease of assembly of the electrode assembly 300, space for electrical connection, the required amount of electrolyte 400 to be injected, etc. However, such marginal space may cause a rocking phenomenon in which the electrode assembly 300 in the case 100 rocks or slides due to an external impact.

[0065] To solve this problem, the prismatic secondary battery 10 of the present invention has a swelling tape 500 attached to the surface of the electrode assembly 300. The swelling tape 500, which is made of an expandable material that reacts with the electrolyte 400, does not have a thickness sufficient to completely fill the gap between the electrode assembly 300 and the case 100 in the initial state when it is not in contact with the electrolyte 400. As a result, when the electrode assembly 300 to which the swelling tape 500 is attached is housed in the case 100, good assembly properties are maintained.

[0066] When the electrode assembly 300 to which the swelling tape 500 is attached is completely housed in the case 100, the electrolyte 400 comes into contact with the swelling tape 500, causing the swelling tape 500 to elongate or expand. When the swelling tape 500 expands in volume, it fills the gap between the electrode assembly 300 and the case 100, and even when it expands in length, it fills the gap by forming a curved three-dimensional shape due to the balance between the force generated by the expansion of the base layer of the swelling tape 500 and the fixing force of the adhesive layer.

[0067] The substrate layer of the swelling tape 500 is made of a material that expands in length or volume when it comes into contact with a liquid such as the electrolyte 400, and the shape of the substrate layer is not particularly limited. For example, it may be in the form of a film or sheet.

[0068] The material of the substrate layer may be any material that has the property of expanding when it comes into contact with a liquid. As an example, the substrate layer may be a polymer film or sheet that is manufactured to exhibit the property of expanding when it comes into contact with a fluid by a stretching or shrinking process during the manufacturing process.

[0069] In one example, the substrate layer may be a substrate layer containing a urethane bond, an ester bond, or an ether bond, or a cellulose ester compound. Examples of such substrate layers include an acrylate-based substrate layer, a urethane-based substrate layer, an epoxy-based substrate layer, and a cellulose-based substrate layer.

[0070] The swelling tape 500 having such expansion properties is attached to the surface of the electrode assembly 300 via an adhesive layer, and extends or expands upon contact with the electrolyte 400 filled in the case 100, eliminating any gap between the electrode assembly 300 and the case 100, thereby preventing the electrode assembly 300 from shaking. As the electrode assembly 300 is stably supported via the swelling tape 500, problems such as short circuits of the electrode tabs 310 are eliminated, and the safety of the prismatic secondary battery 10 is improved.

[0071] In addition, in the prismatic secondary battery 10 of the present invention, a concave first beading processing portion 600 is formed on at least two opposing surfaces along the front, rear, left and right edges of the case 100. The first beading processing portion 600 forms a thin linear concave surface, and the concave surface of the first beading processing portion 600 has a depth that presses the electrode assembly 300 housed inside the case 100. More precisely, the concave surface of the first beading processing portion 600 directly presses the surface of the swelling tape 500 attached to the surface of the electrode assembly 300, thereby indirectly pressing the electrode assembly 300.

[0072] Since the first beading processing portion 600 has a thin linear shape, even if a concave surface is formed on the inside of the case 100, the effect on the capacity of the prismatic secondary battery 10 is very small. In other words, the effect of the first beading processing portion 600 on the capacity or size of the essential components of the prismatic secondary battery 10 housed inside the case 100, such as the electrode assembly 300 and / or the electrolyte 400, is very limited.

[0073] 1, the first beading processing parts 600 formed on at least two opposing surfaces along the front, rear, left and right edges of the case 100 press the surface of the electrode assembly 300 from both opposing directions. That is, the electrode assembly 300 having a surplus space with respect to the case 100 is pressed and fixed from both directions by the opposing first beading processing parts 600, thereby improving the support structure of the electrode assembly 300 and suppressing the slip phenomenon during use. As a result, the fluidity of the electrode assembly 300 is more reliably restricted by both the swelling tape 500 and the first beading processing parts 600, preventing various problems such as short circuits due to electrical contact and breakage of tabs, and thus significantly improving the safety of the prismatic secondary battery 10.

[0074] Meanwhile, the first embodiment of the present invention provides various embodiments of the attachment structure of the swelling tape 500. For example, as shown in Fig. 2, the swelling tape 500 may be attached to all four sides of the electrode assembly 300, i.e., the front, back, left and right. By attaching the swelling tape 500 to the front, back, left and right of the electrode assembly 300, the occurrence of oscillation in the front, back and left and right directions is suppressed.

[0075] In the illustrated embodiment, the swelling tape 500 is continuously attached around the edges of the front, rear, left and right sides of the electrode assembly 300, which is a particularly efficient attachment structure when the swelling tape 500 is attached automatically / semi-automatically using a roll-type wound swelling tape 500.

[0076] In addition, since the width of the swelling tape 500 corresponds to the width of the electrode assembly 300, the swelling tape 500 can be continuously attached to the entire front, back, left and right surfaces of the electrode assembly 300. Since the swelling tape 500 has insulating properties, the swelling tape 500 protects the entire front, back, left and right surfaces of the electrode assembly 300, which is more advantageous in preventing problems such as electrical shorts.

[0077] In order to further enhance the functionality of the swelling tape 500, the attachment structure of the swelling tape 500 may be provided with some gaps.

[0078] 3 is a perspective view illustrating an attachment structure of the swelling tape 500 having a first gap 510. Referring to FIG 3, the swelling tape 500 is attached along the edges of the front, rear, left and right sides of the electrode assembly 300, and the first gap 510 is formed along the entire edges between the front, rear, left and right sides of the electrode assembly 300.

[0079] In other words, the embodiment of FIG. 3 has a structure in which the swelling tapes 500 attached to the front, back, left and right surfaces of the electrode assembly 300 are separated from each other at the four edges of the electrode assembly 300.

[0080] This is in consideration of the disadvantage that if the swelling tape 500 is attached continuously around the edges of the front, back, left and right sides of the electrode assembly 300 as in the embodiment of FIG. 2, the swelling tape 500 will bend at the edges, in which case stress will be concentrated at the right-angle bent portions of the swelling tape 500.

[0081] If stress is concentrated at the bent portion of the swelling tape 500, a strong force acts on the edge of the electrode assembly 300 when the swelling tape 500 expands, which may cause deformation of the electrode assembly 300. The embodiment of FIG. 3 solves this problem of stress concentration by forming first blank portions 510 along the entire edges between the front, rear, left and right sides of the electrode assembly 300 in the swelling tape 500.

[0082] 4 and 5 are perspective views respectively illustrating an attachment structure of the swelling tape 500 having the second blank portion 520. For reference, although both Fig. 4 and Fig. 5 are illustrated as having the first blank portion 510, the first blank portion 510 and the second blank portion 520 are independent configurations and do not necessarily need to be combined together.

[0083] The second blank portion 520 is a blank portion formed in the center of the front and rear surfaces of the electrode assembly 300. As shown in FIG. 4, the second blank portion 520 may have a closed shape inside the swelling tape 500, or as shown in FIG. 5, the second blank portion 520 may have a shape that disconnects both sides of the swelling tape 500 attached to the front and rear surfaces of the electrode assembly 300.

[0084] The second blank portion 520 is intended to form a space for restoring a certain amount of the electrolyte 400 that is reduced due to the volume occupied by the swelling tape 500, and also to accommodate the phenomenon (swelling phenomenon) in which the central portion of the electrode assembly 300 swells as the charge / discharge cycle is repeated.

[0085] Here, the front and rear surfaces of the electrode assembly 300 are referred to based on the drawings and also refer to the widest surfaces of the prismatic secondary battery 10 when viewed from the topography. In other words, it is the originally intended purpose that the second blank portion 520 is formed on the widest surface of the electrode assembly 300.

[0086] 6 illustrates an embodiment in which a third blank portion 530 is formed in the center of the left and right sides of the electrode assembly 300. The third blank portion 530 is intended to complement the second blank portion 520, and is preferably provided together with the second blank portion 520.

[0087] Second embodiment The second embodiment of the present invention provides various embodiments of the beading processing unit. In the second embodiment, the beading processing unit includes a first beading processing unit 600 and a second beading processing unit 610.

[0088] FIG. 7 is a cross-sectional view illustrating a structure in which the first beading processor 600 supports the electrode assembly 300, and FIG. 8 is a view illustrating the relative positions of the first beading processor 600 and the electrode assembly 300. As shown in FIG.

[0089] 7, the first beading processing unit 600 presses the surface of the swelling tape 500 attached to the electrode assembly 300 housed inside the case 100. More specifically, the concave surface of the first beading processing unit 600 directly presses the surface of the swelling tape 500 attached to the surface of the electrode assembly 300, thereby indirectly compressing the electrode assembly 300. As a result, the electrode assembly 300 inside the case 100 is not damaged by the pressure of the first beading processing unit 600, and the support structure thereof is significantly improved.

[0090] 8 is a view illustrating the front of the prismatic secondary battery 10, with the electrode assembly 300 housed inside the case 100 shown by hidden lines. The first beading processing part 600 is formed at a position spaced apart from the electrode tab 310 of the electrode assembly 300. This is to prevent the first beading processing part 600 from directly pressing the electrode tab 310 and generating stress in the electrode tab 310, and also to ensure that the position of the first beading processing part 600 faces the swelling tape 500.

[0091] In addition, the first beading processing portion 600 may be formed adjacent to the cap plate 200 forming the upper surface of the case 100 so as to press the upper portion of the electrode assembly 300 housed inside the case 100 .

[0092] The first beading processing part 600 may be formed on the two surfaces of the case 100 that have the longest widthwise length among the front, rear, left and right edges, i.e., the front and rear surfaces of the case 100 based on the drawing. As a result, the first beading processing part 600 may be formed to a sufficient length, so that the electrode assembly 300 can be firmly supported. Alternatively, as shown in FIG. 1, the first beading processing part 600 may be formed continuously on four surfaces along the front, rear, left and right edges of the case 100, so that the electrode assembly 300 can be more securely supported by indirectly pressing the electrode assembly 300 from all four sides.

[0093] Meanwhile, FIG. 9 is an oblique view illustrating an embodiment having a first beading processing portion 600 and a second beading processing portion 610, and FIG. 10 is a cross-sectional view illustrating a structure in which the first beading processing portion 600 and the second beading processing portion 610 support the electrode assembly 300.

[0094] As shown in Figures 9 and 10, according to another embodiment of the second embodiment, the case 100 further includes a second beading processing portion 610 formed on at least two opposing surfaces along the front, rear, left and right edges at a height adjacent to the bottom surface of the case 100.

[0095] The second beading processing unit 610 is an additional component that complements the above-mentioned first beading processing unit 600 and more reliably prevents the slip phenomenon of the electrode assembly 300. The first beading processing unit 600 presses and supports the upper part of the electrode assembly 300, while the second beading processing unit 610 supports the lower part of the electrode assembly 300.

[0096] 10, the second beading processing unit 610 contacts and supports the bottom surface of the electrode assembly 300 without pressing the surface of the electrode assembly 300 housed inside the case 100. That is, the second beading processing unit 610 does not directly press the electrode assembly 300, but plays a role in supporting the bottom surface to prevent the electrode assembly 300 from sliding downward.

[0097] In this embodiment, the second beading processing part 610 supports the bottom surface of the electrode assembly 300, while the first beading processing part 600 presses and fixes the upper part of the electrode assembly 300, so that the slip phenomenon of the electrode assembly 300 is completely eliminated.

[0098] Here, the reason why the second beading processing portion 610 is not formed as a structure that compresses the electrode assembly 300 is that it is considered that unintended deformation may occur in the electrode assembly 300 during the process of inserting the electrode assembly 300 so that both the upper and lower parts of the electrode assembly 300 are fixed, and that if a swelling phenomenon occurs in the electrode assembly 300 due to repeated charging and discharging of the rectangular secondary battery 10, the compressive structure of the second beading processing portion 610 may get in the way when accommodating the deformation of the electrode assembly 300.

[0099] Similarly to the first beading processed portion 600, the second beading processed portion 610 may be formed on the front and rear surfaces that have the longest widthwise length among the front, rear, left and right edges of the case 100, or may be formed continuously on all four sides along the front, rear, left and right edges of the case 100. Fig. 9 shows an embodiment in which the second beading processed portion 610 is formed continuously on all four sides along the front, rear, left and right edges of the case 100.

[0100] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations described in the drawings or embodiments, etc. in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, so it is understood that there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0101] 10: Square secondary battery 100:Case 200: Cap plate 210: Electrode terminal 300: Electrode assembly 310: Electrode tab 312: Positive electrode tab 314: Negative electrode tab 400: Electrolyte 500: Swelling tape 510: 1st blank area 520:Second blank space 530: 3rd blank space 600: First beading processing section 610: Second beading processing section

Claims

1. A case in which at least one surface forms an open surface; an electrode assembly that is housed inside the case through an open surface of the case; a cap plate that is coupled to the open surface of the case in a sealing manner and that is provided with positive and negative electrode terminals; A swelling tape is attached to a surface of the electrode assembly, the swelling tape expanding or contracting upon contact with the electrolyte filled in the case. A rectangular secondary battery, wherein a first concave beading process portion is formed on at least two mutually opposing faces along the front, rear, left and right edges of the case.

2. The prismatic secondary battery according to claim 1 , wherein the swelling tape is elongated or volumically expanded in a longitudinal direction upon contact with the electrolyte.

3. The swelling tape is The prismatic secondary battery of claim 1 , wherein the insulating layer is attached to the front, rear, left and right sides of the electrode assembly.

4. The swelling tape is The prismatic secondary battery of claim 3 , wherein the electrode assembly is continuously attached along the edges of the front, rear, left and right sides.

5. The swelling tape is The prismatic secondary battery of claim 3 , wherein the electrode assembly is attached along edges of the front, rear, left and right sides, and a first blank portion is formed along the entire edges between the front, rear, left and right sides of the electrode assembly.

6. The swelling tape is The prismatic secondary battery according to claim 5 , wherein a second blank portion is formed at the center of the front and rear surfaces of the electrode assembly.

7. The prismatic secondary battery of claim 6 , wherein both sides of the swelling tape attached to the front and rear surfaces of the electrode assembly are interrupted by the second blank portion.

8. The swelling tape is The prismatic secondary battery according to claim 6 or 7, wherein a third blank portion is formed in the center of the left and right side surfaces of the electrode assembly.

9. The first beading processing section is The prismatic secondary battery of claim 1 , wherein a surface of the swelling tape attached to the electrode assembly housed inside the case is compressed.

10. The first beading processing section is the electrode tab of the electrode assembly housed inside the case is formed at a position spaced apart from the electrode tab, The prismatic secondary battery of claim 9 , wherein the electrode assembly is formed adjacent to the cap plate so as to press against an upper portion of the electrode assembly housed inside the case.

11. The first beading processing section is The prismatic secondary battery according to claim 9 , wherein the insulating layer is formed continuously over four sides along the front, rear, left and right edges of the case.

12. The prismatic secondary battery according to claim 10 , further comprising second beading processed portions formed on at least two opposing surfaces along front, rear, left and right edges at a height adjacent to the bottom surface of the case.

13. The second beading processing section is The prismatic secondary battery of claim 12 , further comprising a support for a lower portion of the electrode assembly housed inside the case.

14. The second beading processing section is The prismatic secondary battery of claim 12 , wherein the electrode assembly is supported by contacting a bottom surface of the electrode assembly.

Images