Electrode assembly

Abstract

The present application can provide an electrode assembly in which positional errors that may occur during a notching process or an alignment process are minimized. Furthermore, the present application can provide an electrode assembly in which damage to the separator is minimized and stress concentration at the boundary is prevented by eliminating the sharp boundary of the active material layer formed by cutting in the vertical direction during the notching process.

Description

Technology Field

[0001] The present application relates to an electrode assembly and the use of said electrode assembly. Background Technology

[0002] As technology development and demand for mobile devices and electric vehicles increase, the demand for secondary batteries as an energy source is increasing, and accordingly, much research is being conducted to meet various requirements. Nickel-hydrogen batteries, lithium batteries, and lithium-ion batteries are used as secondary batteries, with lithium-ion batteries being the representative type.

[0003] These secondary batteries are classified into lithium-ion batteries, lithium-ion polymer batteries, and lithium-polymer batteries depending on the composition of the electrodes and electrolytes; among them, the use of lithium-ion polymer batteries is increasing because they have a low possibility of electrolyte leakage and are easy to manufacture. Generally, secondary batteries are classified according to the shape of the battery case into cylindrical batteries and prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries, in which the electrode assembly is housed in a pouch-type case made of aluminum laminate sheets.

[0004] The electrode assembly embedded in the battery case is a power generation element capable of charging and discharging, comprising a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode. It is classified into a jelly-roll type, which is wound with a separator interposed between a long sheet-type positive electrode and a negative electrode coated with an active material, and a stack type, which is sequentially stacked with a plurality of positive electrodes and negative electrodes of a predetermined size interposed in the separator. Such an electrode assembly is disclosed in Patent Document 1 (Korean Patent Publication No. 10-2008-0052869).

[0005] Recently, in order to improve capacity without increasing the overall volume by integrating secondary batteries, it is necessary to efficiently form an active material layer containing an electrode active material over a larger area on the electrode plate.

[0006] However, positional errors may occur in the process of notching multiple electrodes or aligning the electrodes, and the quality of the battery manufacturing may deteriorate due to said positional errors.

[0007] Furthermore, since the notching process of the electrode is generally performed in a vertical direction, the active material layer of the electrode has sharp boundaries, and there was a problem of quality degradation due to stress concentration at these sharp boundaries. In addition, there was also a problem where the sharp boundaries of the active material layer came into contact with and damaged the separator. Prior art literature

[0008] Republic of Korea Patent Publication No. 10-2008-0052869 The problem to be solved

[0009] The present application aims to provide an electrode assembly in which positional error that may occur during a notching process or an alignment process is minimized.

[0010] In addition, the present application aims to provide an electrode assembly that prevents stress concentration at the boundary and minimizes damage to the separator by eliminating the sharp boundary of the active material layer formed by cutting in the vertical direction during the notching process. means of solving the problem

[0011] An electrode assembly according to one example of the present application comprises: an anode plate having an anode tab protruding from one outer circumferential end and an anode active material layer including an anode active material formed on the lower part of the anode tab and on a current collector; a cathode plate having a cathode tab protruding from one outer circumferential end and a cathode active material layer including a cathode active material formed on the lower part of the cathode tab and on a current collector; and a separator interposed between the anode plate and the cathode plate, wherein a capacitance excess portion is included at one outer circumferential end of the cathode plate facing the anode tab, and the cathode active material layer formed on the capacitance excess portion has a sloped structure. Effects of the invention

[0012] The present application can provide an electrode assembly in which positional error that may occur during a notching process or alignment process is minimized.

[0013] In addition, the present application can provide an electrode assembly that prevents stress concentration at the boundary and minimizes damage to the separator by removing the sharp boundary of the active material layer formed by cutting in the vertical direction during the notching process. Brief explanation of the drawing

[0014] FIG. 1 is an exemplary drawing showing an electrode assembly according to one example of the present application. FIG. 2 is an exemplary drawing showing an anode plate according to one example of the present application. FIG. 3 is a top view of an anode plate according to an example of the present application. FIG. 4 is an exemplary drawing showing a cathode plate according to one example of the present application. FIG. 5 shows an example of a negative electrode active material layer on the excess capacitance portion and a volume ratio (R V It is a drawing to explain ). FIG. 6 is a top view of a cathode plate according to one example of the present application. FIG. 7 is a top view of a capacity excess portion according to an example of the present application. Specific details for implementing the invention

[0015] The term "room temperature" as used in this application refers to a natural temperature that is not heated or cooled, and may mean, for example, any temperature within the range of 10°C to 30°C, for example, about 15°C or higher, about 18°C ​​or higher, about 20°C or higher, about 23°C or higher, about 27°C or lower, or 25°C. Furthermore, among the physical properties mentioned in this application, if the measured temperature affects the physical property, unless specifically otherwise specified, said physical property is the property measured at room temperature. Also, unless specifically otherwise specified, the unit of temperature in this application is Celsius.

[0016] As used in this application, the term "thickness" refers to the average thickness unless otherwise noted.

[0018] Hereinafter, the present invention will be described with reference to the drawings according to embodiments thereof, but this is for the purpose of facilitating a better understanding of the present invention and does not limit the scope of the present invention.

[0019] An electrode assembly (1) according to one example of the present application may include an anode plate (10), a cathode plate (20), and a separator (30). FIG. 1 is an exemplary drawing showing an electrode assembly (1) according to one example of the present application. Referring to FIG. 1, the electrode assembly (1) according to one example of the present application may have a stack-type structure in which a separator (30) is introduced between the anode plate (10) and the cathode plate (20). In addition, although not shown in the drawing, the electrode assembly (1) may have a stack / folding-type structure in addition to a stack-type structure.

[0020] An electrode assembly (1) according to one example of the present application may have a rectangular or square shape in a planar shape. When the electrode assembly (1) has a rectangular or square shape in a planar shape, spatial efficiency can be secured when arranging a plurality of electrode assemblies (1).

[0021] In one example of the present application, the electrode assembly (1) may have the positive electrode tab (11) and the negative electrode tab (21) formed in opposite directions.

[0022] In an example of the present application, the electrode assembly (1) may have a negative plate (20) with a relatively larger area than the positive plate (10). By designing the negative plate (20) to have a relatively larger area than the positive plate (10), the deterioration of the battery cell quality due to lithium (Li) precipitation can be prevented. Although FIG. 1 shows the negative plate (20) and the positive plate (10) as having the same size, this is merely for convenience of explanation, and as described above, the negative plate (20) may have a relatively larger area than the positive plate (10).

[0023] positive plate

[0024] In one example of the present application, the positive plate (10) may have a positive tab (11) protruding from one outer circumference end, and a positive active material layer (12) containing a positive active material may be formed on the lower part of the positive tab (11) and on a current collector (13).

[0025] FIG. 2 is an exemplary drawing showing a positive plate (10) according to an example of the present application. Referring to FIG. 2, the positive plate (10) may have a structure in which a positive active material layer (12) is formed on both sides of a positive current collector (13). Additionally, although not shown in the drawing, the positive plate (10) may have a structure in which a positive active material layer (12) is formed on only one side of a positive current collector (13).

[0026] The positive active material layer (12) included in the above positive plate (10) may include a positive active material and a binder for the positive active material.

[0027] The above-mentioned cathode active material is not particularly limited, but, for example, layered compounds such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; lithium iron phosphate such as LiFePO4; chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Examples include lithium manganese composite oxides represented by O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, satisfying 0.01≤c3≤0.1) or Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn); and LiMn2O4 in which part of the Li of the chemical formula is substituted with alkaline earth metal ions, but are not limited to these.

[0028] The above positive active material layer (12) may contain a positive active material in a range of about 80% to 99.5% by weight, preferably 88% to 99% by weight, relative to the total weight.

[0029] The above-mentioned binder for the positive active material serves to improve adhesion between positive active materials and adhesion between the positive active material layer (12) and the current collector (13). The binder for the above-mentioned cathode active material is not particularly limited, but includes polyvinylidene fluoride (PVdF), polyvinyl alcohol, polyimide, polyamideimide, styrene butadiene rubber, polyethylene oxide, carboxyl methyl cellulose, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethyl methacrylate, and polybutylacrylate. One or more may be selected from the group consisting of polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate copolymer, and polyarylate, and preferably one or more may be selected from the group consisting of non-aqueous polyvinylidene fluoride, polyimide, and polyamideimide in terms of adhesion, chemical resistance, and electrochemical stability, and more preferably polyvinylidene fluoride.

[0030] When the binder for the anode active material comprises polyvinylidene fluoride, the polyvinylidene fluoride may have a weight-average molecular weight in the range of 400,000 g / mol to 1,500,000 g / mol, preferably 600,000 g / mol to 1,200,000 g / mol, in order to improve adhesion between the aforementioned active materials and secure the desired viscosity. Here, the weight-average molecular weight can be measured using gel permeation chromatography (GPC). Additionally, the polyvinylidene fluoride may have a melting point of 150°C to 180°C, preferably 165°C to 175°C, to improve solubility. Here, the melting point can be measured using differential scanning calorimetry (DSC).

[0031] The above positive active material layer (12) may contain a binder for the positive active material in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the positive active material.

[0032] The positive active material layer (12) included in the positive plate (10) may additionally include a conductive material. The conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and, for example, one or more selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farness black, lamp black, thermal black; conductive fiber such as carbon fiber or metal fiber; conductive tube such as carbon nanotube (CNT); metal powder such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0033] The above positive active material layer (12) may contain a conductive material in an amount of 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, relative to 100 parts by weight of the positive active material.

[0034] In addition, the positive active material layer (12) may have a thickness within the range of 1 to 500 μm.

[0035] The positive current collector (13) included in the positive plate (10) is not particularly limited in type, size, or shape, as long as it is conductive without causing chemical changes in the battery. For example, the positive current collector (13) may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc. Fine irregularities may be formed on the surface of the positive current collector (13) to increase the adhesion of the positive active material, and various forms such as film, sheet, foil, net, porous body, foam, and nonwoven fabric are possible. In addition, the positive current collector (13) may have a thickness within the range of 3 to 500 μm.

[0036] According to one example of the present application, the positive plate (10) may include an insulating layer on at least a portion of the positive active material layer (12). Here, the insulating layer may be positioned to cover at least a portion of the surface of the positive active material layer (12) and at least a portion of the surface of the non-positive portion of the current collector (13) where the positive active material layer (12) is not located. That is, the insulating layer according to one example of the present application can minimize a short circuit that may occur between the positive plate (10) and the negative plate (20) by covering at least a portion of the retaining portion (where the positive active material layer is located) and at least a portion of the non-positive portion (where the positive active material layer is not located) on the current collector (13).

[0037] The above insulating layer may include a binder for the insulating layer. The binder for the insulating layer is not particularly limited in type as long as it can provide bonding between the positive active material layer (12) and the positive current collector (13) or between the insulating layer and the positive current collector (13). Examples include polyvinylidene fluoride (PVdF), polyvinyl alcohol, styrene butadiene rubber, styrene butadiene latex, polyethylene oxide, carboxyl methyl cellulose, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. One or more may be selected from the group consisting of sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate copolymer, and polyarylate, and preferably may be polyvinylidene fluoride (PVdF), styrene-butadiene rubber, styrene-butadiene latex, or a mixture thereof in terms of adhesion, chemical resistance, and electrochemical stability.

[0038] In addition, the binder for the insulating layer may use the same compound as the binder for the positive active material. In this case, the bonding strength may be further improved in the overlapping region of the positive active material layer (12) and the insulating layer, and as a result, the stability, adhesion, bonding strength, and processability of the product may be improved.

[0039] FIG. 3 is a top view of a positive plate (10) according to an example of the present application. Referring to FIG. 3, the positive tab (11) may extend from the positive current collector (13) and protrude from one outer circumference end of the positive plate (10), and the positive active material layer (12) may be formed on the lower part (15) of the positive tab (11) and on the positive current collector (13).

[0040] Referring to FIG. 3, the centerline of the positive tab (11) may be formed to coincide with the centerline of the positive current collector (13). That is, the positive tab (11) and the positive current collector (13) may be aligned so that their centers coincide with each other. Here, the centerline may refer to an imaginary line that has the same width (w) on the left and right sides with respect to the width direction (w) of the object.

[0041] In addition, the width (w2) of the positive current collector (13) may be 10 mm or more, 25 mm or more, 50 mm or more, 75 mm or more, 100 mm or more, 125 mm or more, 150 mm or more, 175 mm or more, or 200 mm or more, or 500 mm or less, 480 mm or less, 460 mm or less, 440 mm or less, 420 mm or less, or 400 mm or less.

[0042] Additionally, the width (w1) of the positive tab (11) may be 10 mm or more, 20 mm or more, 30 mm or more, 40 mm or more, 50 mm or more, 60 mm or more, 70 mm or more, 80 mm or more, 90 mm or more, or 100 mm or more, or 200 mm or less, 190 mm or less, 180 mm or less, 170 mm or less, 160 mm or less, or 150 mm or less.

[0043] When the width (w2) of the anode current collector (13) and the width (w1) of the anode tab (11) each satisfy the above range, the stability of electron movement can be secured.

[0044] Referring to FIG. 3, the positive tab (11) may be structured to protrude by a predetermined distance (h2) from one end of an adjacent positive current collector (13). At this time, the predetermined distance (h2) may be 10 mm or more, 15 mm or more, 20 mm or more, 25 mm or more, 30 mm or more, 35 mm or more, 40 mm or more, 45 mm or more, or 50 mm or more, or 100 mm or less, 95 mm or less, 90 mm or less, 85 mm or less, 80 mm or less, 75 mm or less, 70 mm or less, 65 mm or less, or 60 mm or less.

[0045] Additionally, a positive active material layer (12) may be formed on at least a portion of the positive tab (11), and may be formed at a predetermined distance (h1) from one end of the positive current collector (13) adjacent to the positive tab (11). At this time, the predetermined distance (h1) may be 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, or 1 mm or more, or 5 mm or less, 4.8 mm or less, 4.6 mm or less, 4.4 mm or less, 4.2 mm or less, 4 mm or less, 3.8 mm or less, 3.6 mm or less, 3.4 mm or less, 3.2 mm or less, or 3 mm or less.

[0046] The safety of the battery can be ensured if each of the predetermined distance (h2) from one end of the adjacent positive current collector (13) and the predetermined distance (h1) from one end of the positive current collector (13) adjacent to the positive tab (11) satisfies the above range.

[0047] cathode plate

[0048] In one example of the present application, a negative plate (20) may have a negative tab (21) protruding from one outer circumference end, and a negative active material layer (22) containing a negative active material may be formed on the lower part of the negative tab (21) and on a current collector (23).

[0049] FIG. 4 is an exemplary drawing showing a cathode plate (20) according to an example of the present application. Referring to FIG. 4, the cathode plate (20) may have a structure in which a cathode active material layer (22) is formed on both sides of a cathode current collector (23). Additionally, although not shown in the drawing, the cathode plate (20) may have a structure in which a cathode active material layer (22) is formed on only one side of the cathode current collector (23).

[0050] The negative active material layer (22) included in the above negative plate (20) may include a negative active material and a binder for the negative active material.

[0051] The above-mentioned negative electrode active material is not particularly limited, but a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO₂ β Examples include metal oxides capable of doping and dedoping lithium, such as (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Furthermore, the carbon material may include low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0052] The above negative electrode active material layer (22) may contain a negative electrode active material in a range of about 80% to 99.5% by weight, preferably 88% to 99% by weight, relative to the total weight.

[0053] The above-mentioned binder for the negative electrode active material serves to improve adhesion between the negative electrode active materials and the adhesion between the negative electrode active material layer (22) and the current collector (23). The binder for the above-mentioned cathode active material is not particularly limited, but includes polyvinylidene fluoride (PVdF), polyvinyl alcohol, polyimide, polyamideimide, styrene butadiene rubber, polyethylene oxide, carboxyl methyl cellulose, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and polymethyl methacrylate. One or more may be selected from the group consisting of polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate copolymer, and polyarylate, and preferably one or more may be selected from the group consisting of non-aqueous polyvinylidene fluoride, polyimide, and polyamideimide in terms of adhesion, chemical resistance, and electrochemical stability, and more preferably polyvinylidene fluoride.

[0054] When the binder for the cathode active material comprises polyvinylidene fluoride, the polyvinylidene fluoride may have a weight-average molecular weight in the range of 400,000 g / mol to 1,500,000 g / mol, preferably 600,000 g / mol to 1,200,000 g / mol, in order to improve adhesion between the aforementioned active materials and secure the desired viscosity. Here, the weight-average molecular weight can be measured using gel permeation chromatography (GPC). Additionally, the polyvinylidene fluoride may have a melting point of 150°C to 180°C, preferably 165°C to 175°C, to improve solubility. Here, the melting point can be measured using differential scanning calorimetry (DSC).

[0055] The above negative electrode active material layer (22) may contain a binder for the negative electrode active material in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the negative electrode active material.

[0056] The negative electrode active material layer (22) included in the above negative electrode plate (20) may additionally include a conductive material. The conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farness black, lamp black, thermal black; conductive fibers such as carbon fiber or metal fiber; conductive tubes such as carbon nanotubes (CNT); metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0057] The above negative electrode active material layer (22) may contain a conductive material in an amount of 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, relative to 100 parts by weight of the negative electrode active material.

[0058] In addition, the negative electrode active material layer (22) may have a thickness within the range of 1 to 500 μm.

[0059] The negative current collector included in the above negative plate (20) is not particularly limited in type, size, shape, etc., as long as it is conductive without causing chemical changes in the battery. Examples of the above negative current collectors may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloys. In addition, similar to the positive current collector, fine irregularities may be formed on the surface to strengthen the bonding strength of the negative active material, and it may be used in various forms such as film, sheet, foil, net, porous body, foam, nonwoven fabric, etc. The above negative current collector (23) may have a thickness within the range of 3 to 500 μm.

[0060] A negative electrode plate (20) according to one example of the present application may also include an insulating layer on at least a portion of the negative active material layer (22), similar to the positive electrode plate (10) described above. Since the insulating layer has the same characteristics as the insulating layer of the positive electrode plate (10), specific details are omitted.

[0061] A cathode plate (20) according to one example of the present application may include a capacitance excess portion (24) at one outer circumference end of the cathode plate (20). Referring to FIG. 4, the capacitance excess portion (24) may be formed in a direction opposite to that of the cathode tab (21) of the cathode plate (20).

[0062] As described above, in an example of the present application, the electrode assembly (1) may have the positive electrode tab (11) and the negative electrode tab (21) formed in opposite directions, and the capacity excess portion (24) may face the positive electrode tab (11). That is, the capacity excess portion (24) may be included at one outer circumference end of the negative electrode plate (20) facing the positive electrode tab (11).

[0063] Referring to FIG. 4, a negative active material layer (22) may be formed on the capacity excess portion (24). As shown in FIG. 4, the negative active material layer (22) may be formed on both sides of the capacity excess portion (24), and although not shown in the drawing, the negative active material layer (22) may be formed on only one side of the capacity excess portion (24).

[0064] Additionally, referring to FIG. 4, the negative active material layer (22) formed on the capacity excess portion (24) may have a sloped structure. The sloped structure may be suitable as a curved profile so that the negative active material layer (22) does not have sharp corners. The sloped structure may be formed by applying a negative slurry that forms the negative active material layer (22) on the negative current collector (23) such that at least one edge forms a curved profile, and then performing a notching process controlled so that the curved profile is not destroyed after drying and rolling.

[0065] When the negative active material layer (22) formed on the capacity excess portion (24) has an angled corner, there is a high possibility of damage to the separator due to stress concentrated at the corner. When the negative active material layer (22) formed on the capacity excess portion (24) has a sloped structure with a curved profile, the stress is dispersed when manufacturing the electrode assembly (1) or when operating the electrode assembly (1), so damage to the separator caused by the negative active material layer (22) can be prevented.

[0066] The negative active material layer (22) formed on the capacity excess portion (24) according to one example of the present application has a volume ratio (R) according to the following general formula 1. V ) may be 40% or more, 41% or more, 42% or more, 43% or more, 44% or more, or 45% or more. In another example, the above volume ratio (R V ) may be 60% or less, 59% or less, 58% or less, 57% or less, 56% or less, or 55% or less. The above volume ratio (R V ) may be included within a range formed by appropriately selecting the upper and lower limits listed above. The volume ratio (R V If the above range is satisfied, damage to the separator can be prevented while minimizing capacity degradation.

[0067] [General Formula 1]

[0068] R V = V1 / V2 × 100

[0069] In general formula 1, V1 is the volume of a negative active material layer formed to have a sloped structure on the capacity excess portion, and V2 is the volume of a negative active material layer formed to have a hexahedral structure on the capacity excess portion.

[0070] FIG. 5 is an example of a negative active material layer (22) on an excess capacity portion (24) and a volume ratio (R VThis is a drawing for explaining ). Referring to FIG. 5, the left side shows an example of a negative active material layer (22) on a surplus capacity portion (24) according to an example of the present application. The negative active material layer (22) may have a curved profile so as not to have sharp corners and may have a sloped structure. In addition, the volume of the negative active material layer (22) on the surplus capacity portion (24) at this time can be denoted as V1. Also, referring to FIG. 5, the right side shows a negative active material layer (22) formed to have a cuboidal structure on the surplus capacity portion (24), and the volume of the negative active material layer (22) at this time can be denoted as V2. In addition, h, which is the height of each negative active material layer (22) shown in FIG. 5 A wah h B V1 and V2 can be measured respectively under the same conditions. That is, for a negative electrode active material layer (22) having a sloped structure, the average height of the non-sloped portion is h A It can be said that the average height of the negative active material layer (22) having a cuboid structure is h B It can be said that.

[0071] FIG. 6 is a top view of a cathode plate (20) according to an example of the present application. Referring to FIG. 6, a cathode tab (21) may extend from a cathode current collector (23) and protrude from one outer circumference end of the cathode plate (20), and a cathode active material layer (22) may be formed on the lower part (25) of the cathode tab (21) and on the cathode current collector (23).

[0072] Referring to FIG. 6, the centerline of the negative tab (21) may be formed to coincide with the centerline of the negative current collector (23). That is, the negative tab (21) and the negative current collector (23) may be aligned so that their centers coincide with each other.

[0073] Additionally, referring to FIG. 6, the width (w4) of the negative current collector (23) may be 10 mm or more, 25 mm or more, 50 mm or more, 75 mm or more, 100 mm or more, 125 mm or more, 150 mm or more, 175 mm or more, or 200 mm or more, or 500 mm or less, 480 mm or less, 460 mm or less, 440 mm or less, 420 mm or less, or 400 mm or less.

[0074] Additionally, the width (w3) of the cathode tab (21) may be 10 mm or more, 20 mm or more, 30 mm or more, 40 mm or more, 50 mm or more, 60 mm or more, 70 mm or more, 80 mm or more, 90 mm or more, or 100 mm or more, or 200 mm or less, 190 mm or less, 180 mm or less, 170 mm or less, 160 mm or less, or 150 mm or less.

[0075] When the width (w4) of the above-mentioned negative current collector (23) and the width (w3) of the above-mentioned negative tab (21) each satisfy the above range, the stability of electron movement can be secured.

[0076] Referring to FIG. 6, the cathode tab (21) may be structured to protrude a predetermined distance (h4) from one end of an adjacent cathode current collector (23).

[0077] At this time, the above-mentioned predetermined distance (h4) may be 10 mm or more, 15 mm or more, 20 mm or more, 25 mm or more, 30 mm or more, 35 mm or more, 40 mm or more, 45 mm or more, or 50 mm or more, or 100 mm or less, 95 mm or less, 90 mm or less, 85 mm or less, 80 mm or less, 75 mm or less, 70 mm or less, 65 mm or less, or 60 mm or less.

[0078] Additionally, a negative active material layer (22) may be formed on at least a portion of the negative tab (21), and may be formed at a predetermined distance (h3) from one end of the negative current collector (23) adjacent to the negative tab (21).

[0079] At this time, the predetermined distance (h3) may be 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, or 1 mm or more, or 5 mm or less, 4.8 mm or less, 4.6 mm or less, 4.4 mm or less, 4.2 mm or less, 4 mm or less, 3.8 mm or less, 3.6 mm or less, 3.4 mm or less, 3.2 mm or less, or 3 mm or less. If the predetermined distance (h4) from one end of the adjacent negative electrode current collector (23) and the predetermined distance (h3) from one end of the negative electrode current collector (23) adjacent to the negative electrode tab (21) each satisfy the above range, the safety of the battery can be ensured.

[0080] Referring to FIG. 6, the excess capacity portion (24) extends from the negative current collector (23) and may be included at one outer circumference end of the negative plate (20), and may be formed in a direction opposite to that of the negative tab (21) of the negative plate (20).

[0081] Additionally, referring to FIG. 6, the centerline of the capacitance excess portion (24) may be formed to coincide with the centerline of the negative current collector (23). That is, the capacitance excess portion (24) and the negative current collector (23) may be aligned so that their centers coincide with each other.

[0082] Additionally, referring to FIG. 6, the width (w5) of the capacity excess portion (24) may be 10 mm or more, 20 mm or more, 30 mm or more, 40 mm or more, 50 mm or more, 60 mm or more, 70 mm or more, 80 mm or more, 90 mm or more, or 100 mm or more, or 200 mm or less, 190 mm or less, 180 mm or less, 170 mm or less, 160 mm or less, or 150 mm or less.

[0083] If the width (w5) of the above capacity excess portion (24) satisfies the above range, quality degradation due to positional error of the positive plate (10) and negative plate (20) can be prevented when manufacturing the electrode assembly (1).

[0084] In addition, in order to ensure battery stability and prevent quality degradation caused by positional errors of the positive plate (10) and the negative plate (20), it may be preferable that the ratio (w5 / w1) of the width (w1) of the positive tab (11) and the width (w5) of the capacity excess portion (24) be 1.01 or more, 1.015 or more, 1.02 or more, or 1.025 or more, or 1.05 or less, 1.045 or less, 1.04 or less, or 1.035 or less. In addition, to ensure battery stability and prevent quality degradation caused by positional errors of the positive plate (10) and the negative plate (20), the width (w5) of the capacity excess portion (24) may be wider than the width (w1) of the positive tab (11) by at least 1.5 mm, at least 1.75 mm, or at least 2 mm, and in another example, the width (w5) of the capacity excess portion (24) may be wider than the width (w1) of the positive tab (11) by at least 3.5 mm, at least 3.25 mm, or at least 3 mm. The width (w5) of the capacity excess portion (24) may be wider than the width (w1) of the positive tab (11) within a range formed by appropriately selecting the upper and lower limits listed above.

[0085] Additionally, referring to FIG. 6, the excess capacitance portion (24) may be structured to protrude further by a predetermined distance (h5) from one end of the adjacent negative current collector (23). At this time, considering the prevention of quality degradation due to positional errors of the positive plate (10) and the negative plate (20) when manufacturing the electrode assembly (1), the predetermined distance (h5) may be 0.1 mm or more, 0.15 mm or more, or 0.2 mm or more, and in other examples, 1 mm or less, 0.95 mm or less, or 0.9 mm or less. The predetermined distance (h5) may be within a range formed by appropriately selecting the upper and lower limits listed above.

[0086] FIG. 7 is a top view of a capacity excess portion (24) according to an example of the present application. Referring to FIG. 7, the capacity excess portion (24) may have at least one end having a curved structure. In FIG. 7, both ends of the capacity excess portion (24) have a curved structure, but this is merely an example, and at least one end may have a curved structure. The curved structure may be a structure having a round shape processed to form a curved surface.

[0087] The curved structure of the above-mentioned capacity excess portion (24) may have a radius of curvature (r) of 0.1 mm or more, 0.125 mm or more, 0.15 mm or more, or 0.2 mm or more, and in other examples, the radius of curvature (r) may be 0.4 mm or less, 0.375 mm or less, 0.35 mm or less, 0.325 mm or less, or 0.3 mm or less. The radius of curvature (r) may be within a range formed by appropriately selecting the upper and lower limits listed above. When the radius of curvature (r) satisfies the above range, the volume ratio (R) according to the aforementioned general formula 1 V) can be made to satisfy the above range, and ultimately, damage to the separator can be prevented while minimizing capacity degradation. The radius of curvature (r) may refer to the radius of a circle forming the curved structure, and specifically, may refer to the radius of the arc furthest from the curved structure.

[0088] separator

[0089] A separator (30) according to one example of the present application may be interposed between a positive plate (10) and a negative plate (20).

[0090] The separator (30) above separates the positive plate (10) and the negative plate (20) and provides a passage for the movement of lithium ions. Any separator commonly used in the industry can be used without special limitations, and it is particularly desirable that it has low resistance to the movement of ions in the electrolyte and excellent electrolyte moisture retention ability. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like an ethylene polymer, a propylene polymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0092] A battery cell according to one example of the present application may have an electrode assembly (1) according to one example of the present application embedded together with an electrolyte in a battery case.

[0093] The above electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a gel-type polymer electrolyte, a molten inorganic electrolyte, etc., commonly used in the industry, but is not limited thereto. Specifically, the above electrolyte may include an organic solvent and a lithium salt.

[0094] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.In this case, using a mixture of cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9 can result in excellent performance of the electrolyte.

[0095] The above lithium salt can be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. It is preferable to use the lithium salt within the range of 0.1 to 2.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and allow lithium ions to move effectively.

[0096] In addition to the components of the above electrolyte, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be included in an amount of 0.1 to 5 weight% based on the total weight of the electrolyte.

[0097] Additionally, a battery pack according to one example of the present application may include one or more of the battery cells, and a device according to one example of the present application may include the battery pack. The device may be selected from, for example, a computer, a mobile phone, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle, an electric motorcycle, an electric golf cart, or a power storage system. Since the structure and method of manufacturing such a device are known in the art, a detailed description thereof is omitted in this specification.

Claims

Claim 1 A positive plate having a positive tab protruding from one outer circumferential end and a positive active material layer containing a positive active material formed on the lower part of the positive tab and on a current collector; a negative plate having a negative tab protruding from one outer circumferential end and a negative active material layer containing a negative active material formed on the lower part of the negative tab and on a current collector; and a separator interposed between the positive plate and the negative plate, wherein the negative plate facing the positive tab includes a capacitance excess portion at one outer circumferential end, and the negative active material layer formed on the capacitance excess portion has a sloped structure, and a volume ratio (R) according to the following general formula 1 V Electrode assembly in which ) is within the range of 40 to 60%: [General Formula 1]R V = V1 / V2 × 100 In general formula 1, V1 is the volume of a negative active material layer formed to have a sloped structure on the excess capacity portion, and V2 is the volume of a negative active material layer formed to have a hexahedral structure on the excess capacity portion. Claim 2 In paragraph 1, the electrode assembly is an electrode assembly having a stacked or stacked / folded structure. Claim 3 In claim 1, the electrode assembly is an electrode assembly having a rectangular or square shape in planar form. Claim 4 An electrode assembly according to claim 1, wherein the positive electrode tab and the negative electrode tab are formed in opposite directions. Claim 5 In claim 1, the negative electrode plate is an electrode assembly having a relatively larger area than the positive electrode plate. Claim 6 In claim 1, the negative electrode plate and the positive electrode plate are an electrode assembly stacked in a state where their mutual centers coincide. Claim 7 An electrode assembly according to claim 1, wherein the capacitance excess portion has a structure protruding further by a predetermined distance (h5) from one end of an adjacent negative current collector, and the predetermined distance (h5) is within the range of 0.1 to 1 mm. Claim 8 An electrode assembly according to claim 1, wherein the ratio (w5 / w1) of the width of the positive tab (w1) and the width of the capacitance excess portion (w5) is within the range of 1.01 to 1.

05. Claim 9 In claim 1, the width (w5) of the excess capacity portion is wider within the range of 1.5 to 3.5 mm compared to the width (W1) of the anode tab, forming an electrode assembly. Claim 10 In claim 1, the capacitance excess is an electrode assembly having at least one end having a curved structure. Claim 11 An electrode assembly according to claim 10, wherein the radius of curvature of the curved structure is within the range of 0.1 to 0.4 mm. Claim 12 delete Claim 13 A battery cell in which the electrode assembly according to claim 1 is embedded together with an electrolyte in a battery case. Claim 14 A battery pack comprising one or more battery cells according to paragraph 13. Claim 15 A device including a battery pack according to paragraph 14.

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