Electrode assembly

Abstract

The present application may provide an electrode assembly and a use thereof. The present application can provide a structure of an electrode assembly capable of maximizing a capacity ratio per unit area of a positive electrode and a negative electrode while effectively achieving an N / P ratio exceeding 1 in the entire region where the positive electrode and the negative electrode face each other. Accordingly, the present application can provide an electrode assembly capable of maximizing energy density per volume and per weight even in a case where the N / P ratio exceeds 1. The present application may provide a method for manufacturing such an electrode assembly and a use of such an electrode assembly.

Description

Technical Field

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0086635, filed on Jul. 14, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present application relates to an electrode assembly. Background Art

[0003] The application areas of energy storage technology have expanded to mobile phones, cameras, notebook PCs, electric vehicles, etc.

[0004] One of the research fields of energy storage technology is a secondary battery capable of charging and discharging, and research and development have been conducted to improve the capacity density and specific energy of such a secondary battery.

[0005] The secondary battery includes an electrode assembly, which includes a structure in which a positive electrode and a negative electrode are stacked and a separator is inserted between the positive electrode and the negative electrode. When designing the electrode assembly, the negative electrode is made to have a higher and wider load than the positive electrode, that is, the so-called N / P ratio is designed to be greater than 1.

[0006] The N / P ratio is the ratio of the capacity per unit area of ​​the negative electrode to that of the positive electrode, that is, a value obtained by dividing the capacity per unit area of ​​the negative electrode by the capacity per unit area of ​​the positive electrode.

[0007] The reason for designing the N / P ratio to be greater than 1 is because when the negative electrode is not on the opposite surface of the positive electrode during charging, or when the load on the negative electrode is very low, the amount of lithium accepted in the negative electrode is less than the amount of lithium produced in the positive electrode, so there are problems such as lithium electrodeposition (electroplating).

[0008] If the N / P ratio is less than 1, battery short circuit may occur due to needle-shaped precipitation of lithium; since the lithium generated in the positive electrode is not fully utilized during discharge, efficiency reduction and capacity degradation may occur; and the electrolyte decomposes on the surface of the precipitated lithium, causing film growth, thereby efficiency reduction and resistance increase may occur.

[0009] Generally, the negative electrode or the positive electrode is manufactured by coating a slurry containing an electrode active material on the surface of a current collector and undergoing a drying and roll-pressing process, wherein the coated slurry forms an active material layer of the electrode.

[0010] However, if Figure 1 As shown in the example, in the process of coating the slurry on the current collector 100 to form the active material layer 101, due to the characteristics of the slurry, a landslide portion ( Figure 1 S), that is, along the coating direction ( Figure 1 The part where the thickness increases or decreases (in the direction of the arrow in the figure).

[0011] The inclination or width of the landslide portion, etc., depends on the composition of the slurry. When an electrode assembly is formed by making the positive electrode and the negative electrode face each other, an N / P ratio exceeding 1 must be achieved even in the region where the landslide portion exists in the positive electrode and the negative electrode, but since it is not easy to adjust the inclination or width of the landslide portion, adjusting the N / P ratio is also a difficult task.

[0012] Therefore, it is difficult to manufacture the electrode assembly so that the N / P ratio is greater than 1 in the entire region where the negative electrode and the positive electrode face each other.

[0013] Since it is important to achieve an N / P ratio greater than 1, the capacity per unit area of ​​the negative electrode is actually excessive and exceeds the required capacity when designing the electrode.

[0014] In this case, the desired N / P ratio can be achieved, but excess portions are generated in the negative electrode which are not used during actual charging and discharging of the secondary battery, thereby unnecessarily increasing the volume or weight of the electrode assembly or the secondary battery and resulting in inefficiency in terms of energy density. Summary of the invention

[0015] Technical issues

[0016] The present application relates to an electrode assembly and its use. One object of the present application is to provide a structure of an electrode assembly that can maximize the capacity ratio per unit area of ​​the positive electrode to the negative electrode, while effectively achieving an N / P ratio exceeding 1 in the entire area where the positive electrode and the negative electrode are opposite. Therefore, the present application aims to provide an electrode assembly that can maximize the energy density per unit volume and per unit weight even when the N / P ratio exceeds 1.

[0017] The present application also aims to provide a method for manufacturing such an electrode assembly.

[0018] Another object of the present application is to provide a use of an electrode assembly.

[0019] Technical Solution

[0020] The present application relates to an electrode assembly.

[0021] The electrode assembly of the present application includes: a negative electrode, a positive electrode and a separator, wherein

[0022] The negative electrode and the positive electrode can be stacked, and a separator is inserted between the negative electrode and the positive electrode.

[0023] The negative electrode and the positive electrode may respectively include a current collector layer and an active material layer at least present between the current collector layer and the separator,

[0024] The negative electrode and the positive electrode may respectively have a first end portion formed with a pole ear portion and a second end portion opposite to the first end portion.

[0025] The negative electrode and the positive electrode may be stacked in such a manner that the first ends thereof face each other, or in such a manner that the first end of one faces the second end of the other.

[0026] A cut portion may be formed in the active material layer at any one of the first end and the second end of the negative electrode, and a landslide portion may be formed in the active material layer at the other of the first end and the second end of the negative electrode,

[0027] The active material layers at both ends of the positive electrode may be located closer to the inside than the active material layers at both ends of the negative electrode.

[0028] The interval (I) between the positive electrode active material layer and the negative electrode active material layer at the negative end portion forming the landslide portion 2 ) and the interval (I 1 ) ratio I 2 / I 1 It can be in the range of 0.5 to 10.

[0029] In the electrode assembly, the negative electrode active material layer may be thicker than the positive electrode active material layer.

[0030] In the electrode assembly, a landslide portion may be formed in the active material layer at an end portion of the positive terminal opposite to the negative terminal where the cut portion is formed.

[0031] In the electrode assembly, a surface of the landslide portion of the positive electrode active material layer may be a cut surface.

[0032] In the electrode assembly, a cut portion may be formed in the positive electrode active material layer at an end portion opposite to an end portion where a landslide portion of the positive electrode active material layer is formed.

[0033] In the electrode assembly, the cut portion of the positive electrode active material layer may be located more inner than the landslide portion of the negative electrode active material layer.

[0034] The electrode assembly is designed to satisfy the following Formula 1.

[0035] [Formula 1]

[0036] T N / tanθ 1 ≤I 2

[0037] In Formula 1, T N is the thickness of the negative electrode active material layer, θ 1is the inclination angle of the negative landslide part, I 2 It is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative electrode end portion forming the landslide portion.

[0038] Here, tanθ 1 It can be in the range of 0.001 to 10.

[0039] The electrode assembly is designed to further satisfy Formula 2 below.

[0040] [Formula 2]

[0041] I 2 ≤T N / sinθ 1

[0042] In Formula 2, T N is the thickness of the negative electrode active material layer, θ 1 is the inclination angle of the negative landslide part, I 2 It is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative electrode end portion forming the landslide portion.

[0043] In the electrode assembly, a second landslide portion may be formed in the positive electrode active material layer at an end portion opposite to an end portion where the landslide portion of the positive electrode active material layer is formed.

[0044] Here, the surface of the second landslide portion of the positive electrode active material layer may be a cut surface.

[0045] The electrode assembly is designed to satisfy the following formula 3.

[0046] [Formula 3]

[0047] T N / tanθ 1 ≤I 2 +T P / tanθ 2

[0048] In Formula 3, T N is the thickness of the negative electrode active material layer, θ 1 is the inclination angle of the negative landslide part, I 2 is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative end portion forming the landslide portion, T P is the thickness of the positive electrode active material layer, θ 2 is the inclination angle of the second landslide portion of the positive electrode.

[0049] The electrode assembly is designed to further satisfy Formula 4 below.

[0050] [Formula 4]

[0051] I 2 +T P / tanθ 2 ≤T N / sinθ 1

[0052] In Formula 4, T N is the thickness of the negative electrode active material layer, θ 1 is the inclination angle of the negative landslide part, I 2 is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative end portion forming the landslide portion, T P is the thickness of the positive electrode active material layer, θ 2 is the inclination angle of the second landslide portion of the positive electrode.

[0053] The electrode assembly is designed to further satisfy Formula 5 below.

[0054] [Formula 5]

[0055] θ 2 / θ 1 >1

[0056] In Formula 5, θ 1 is the inclination angle of the negative pole landslide part, θ 2 is the inclination angle of the second landslide portion of the positive electrode.

[0057] In the electrode assembly, the negative electrode may also include an active material layer formed on the lateral side opposite to the side of the current collector layer facing the separator, and in this case, the active material layer formed on the lateral side opposite to the side of the current collector layer facing the separator and the active material layer present between the current collector layer and the separator have a symmetrical structure.

[0058] In the electrode assembly, the positive electrode may also include an active material layer formed on the lateral side opposite to the side of the current collector layer facing the separator, and in this case, the active material layer formed on the lateral side opposite to the side of the current collector layer facing the separator and the active material layer present between the current collector layer and the separator have a symmetrical structure.

[0059] The present application also relates to a secondary battery including an electrode assembly and an electrolyte.

[0060] Beneficial Effects

[0061] The present application may provide an electrode assembly and its use. The present application may provide a structure of an electrode assembly that can maximize the capacity ratio per unit area of ​​the positive electrode to the negative electrode, while effectively achieving an N / P ratio exceeding 1 in the entire area where the positive electrode and the negative electrode are opposite. Therefore, even in the case where the N / P ratio exceeds 1, the present application may provide an electrode assembly that can maximize the energy density per unit volume and unit weight. The present application may provide a method for manufacturing such an electrode assembly and the use of such an electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figures 1 to 3 , Figure 6 and Figure 8 is a schematic diagram for explaining the structure of an electrode.

[0063] Figure 4 , Figure 5 and Figure 7 is a schematic diagram for explaining the structure of an electrode assembly.

[0064] Fig. 9 is a schematic diagram for explaining a process of forming a cut portion on an electrode.

[0065] Fig.10 is a schematic diagram for explaining an exemplary structure of a negative electrode included in the electrode assembly of the present application.

[0066] Fig.11 and Fig.12 Schematic diagram for explaining the structure of an electrode assembly of the present application.

[0067] [Explanation of Reference Numerals]

[0068] 200: Diaphragm

[0069] 300: Negative

[0070] 400: Positive

[0071] 100, 103, 104: current collector layer

[0072] 101, 102, 301, 302, 401, 402: Active material layer

[0073] S: Landslide part

[0074] 10: Starting point of active material layer

[0075] NC: Uncoated part

[0076] 1011: Lateral side of the cutting part DETAILED DESCRIPTION

[0077] In this specification, the term "landslide portion" refers to an active material layer region, which includes a current collector layer and an active material layer formed on at least one side of the current collector layer in an electrode cross section, and the thickness of the active material layer significantly increases or decreases along the longitudinal direction of the current collector layer. The increase or decrease in thickness can be achieved at a constant ratio or a variable ratio.

[0078] In this specification, the term "normal thickness region" refers to a region where the thickness of the active material layer remains substantially constant along the longitudinal direction of the current collector layer in the cross section of the electrode.

[0079] Electrode refers to the positive or negative electrode.

[0080] The electrode cross section refers to a section after cutting the electrode along a direction parallel to the line between the end where the uncoated portion exists (when the electrode is viewed from the front) and the end opposite to the end where the uncoated portion exists, and parallel to the normal line of the surface of the current collector layer. The section can be a virtual section or an actual section.

[0081] Hereinafter, in the description of the electrode assembly of the present specification, the positional relationship of the active material layers of the positive electrode and the negative electrode is based on the relationship of the electrode cross sections.

[0082] Figure 2 is a schematic diagram exemplarily showing a cross section of an electrode, such as Figure 2 As shown in , the electrode of the present application may include a current collector layer 100 and active material layers 101, 102 formed on one or both sides of the current collector layer 100. In this case, the active material layers 101, 102 are formed so that there is a portion (so-called uncoated portion) in which the active material layers 101, 102 are not formed in one or more of the two ends of the current collector layer 100. The uncoated portion may form the pole ear portion described below. The uncoated portion may be formed in both ends of the electrode as shown in the figure, or the uncoated portion may be formed only in any one end of the electrode. When there is an uncoated portion in both ends of the electrode, it may be cut in a direction parallel to the line between the two ends of the electrode where the uncoated portion is present.

[0083] Figure 3 When viewed from the front side (the surface where the active material layer 101 is formed) Figure 2 Example of an electrode, and Figure 3 The dotted line in the figure is the cutting line used to observe the electrode cross section. Figure 3 As shown by the dotted line, cutting can be performed along a direction parallel to a line connecting the end where the uncoated portion of the electrode exists (when the electrode is observed from the front) and the end opposite to the end where the uncoated portion exists (or a line connecting the two ends of the uncoated portion of the electrode), parallel to either side of the electrode, and parallel to the normal to the surface of the current collector layer.

[0084] The longitudinal direction of the current collector layer refers to the direction parallel to the current collector layer in the electrode cross section (e.g., Figure 2 direction of the arrow in the figure).

[0085] Generally, an electrode, such as a negative electrode or a positive electrode, is manufactured by coating a slurry containing an electrode active material on one or both sides of a current collector layer and performing a drying and roll-pressing process, and the coated slurry forms an active material layer of the electrode.

[0086] like Figure 2 As shown in FIG. 1 , in such an electrode, due to the characteristics of the slurry, the thickness of the active material layers 101 and 102 is generated along the longitudinal direction of the current collector layer 100 ( Figure 2 The part that increases or decreases significantly (for example, by Figure 2 The part indicated by S).

[0087] In this specification, the portion where the thickness of the active material layer increases or decreases significantly may also be referred to as a landslide portion. The landslide portion may not only occur during the slurry coating process, but may also be formed by etching, cutting or non-contact cutting, etc., which will be described below.

[0088] In addition, in this article, the case where the thickness is significantly increased or decreased means that the portion where the active material layers 101 and 102 in the electrode cross section start (for example, Figure 210) is set as the origin, the distance from the origin to any point of the active material layer 101, 102 measured along the longitudinal direction of the current collector layer is taken as the x-axis value, and the thickness of the active material layer 101, 102 at the relevant distance is taken as the y-axis value, and a curve graph is drawn. At this time, the absolute value of the slope of the relevant curve graph is 0.001 or greater. The length of the x-axis and the thickness of the y-axis have the same unit. Here, when the curve graph is not a straight line, the slope can be a differential value at the relevant point. In another example, the absolute value of the slope of the landslide portion may be greater than or equal to 0.002, greater than or equal to 0.004, greater than or equal to 0.006, greater than or equal to 0.008, greater than or equal to 0.01, greater than or equal to 0.02, greater than or equal to 0.04, greater than or equal to 0.06, greater than or equal to 0.08, greater than or equal to 0.1, greater than or equal to 0.12, greater than or equal to 0.14, greater than or equal to 0.16, greater than or equal to 0.18, or greater than or equal to 0.2; or may be less than or equal to 10, less than or equal to 9, less than or equal to 0. 8, 7, 6, 5, 4, 3, 2, 1, 0.8, 0.6, 0.4, 0.2, 0.1, 0.08, 0.06, 0.04, 0.02, 0.01, 0.008, 0.006, 0.004, 0.002, etc.

[0089] At the same time, when the longitudinal direction of the current collector ( Figure 2 Observe the direction of the arrow in the Figure 2 When the active material layers 101 and 102 of the electrode cross section in FIG. 1 are formed, there is a region where the thickness of the active material layers 101 and 102 remains substantially constant from the end point of the landslide portion to the start point of the landslide portion in the other end, and this region is a normal thickness region. In the normal thickness region, the absolute value of the slope may be in the range of approximately greater than or equal to 0 and less than 0.001. In another example, the upper limit of the absolute value of the slope may be less than or equal to 0.0008, less than or equal to 0.0006, less than or equal to 0.0004, or less than or equal to 0.0002, and so on.

[0090] The electrode assembly of the present application comprises at least a negative electrode, a positive electrode and a separator, wherein the electrode assembly may comprise a negative electrode and a positive electrode in a stacked state, with a separator inserted between the negative electrode and the positive electrode. Figure 4 1 is a schematic diagram showing a structure in which a negative electrode 300 and a positive electrode 400 are stacked with a separator 200 interposed between the negative electrode and the positive electrode.

[0091] like Figure 4As shown, the electrode assembly may include a separator 200, a negative electrode 300 and a positive electrode 400, and may also include any one or more of the two or more of the above. Figure 5 As exemplarily shown, the electrode assembly may also include two or more multi-unit structures in which the negative electrode 300 , the separator 200 , and the positive electrode 400 are sequentially stacked.

[0092] The negative electrode of the electrode assembly may include a current collector layer and an active material layer formed on at least one side of the current collector layer, and the positive electrode may also include a current collector layer and an active material layer formed on at least one side of the current collector layer.

[0093] Figure 6 The negative electrode structure is exemplarily shown, in which active material layers 301 and 302 are formed on both sides of the current collector layer 103. Figure 6 In the embodiment, the active material layers 301 and 302 are formed on both sides of the current collector layer 103 , but the active material layer may be formed only on one side of the current collector layer.

[0094] The positive electrode can also be formed in the same manner as the negative electrode.

[0095] Figure 7 The stacking and Figure 6 The invention relates to a structure in which a negative electrode of the same type and a positive electrode of the same type are provided and a separator is inserted between the negative electrode and the positive electrode, and this structure includes a negative electrode active material layer 302, a negative electrode collector layer 103, a negative electrode active material layer 301, a separator 200, a positive electrode active material layer 401, a positive electrode collector layer 104 and a positive electrode active material layer 402 in sequence.

[0096] In the electrode assembly, the negative electrode and the positive electrode may each include a current collector layer ( Figure 7 103, 104) and in the current collector layer ( Figure 7 103, 104) and diaphragm ( Figure 7 at least one active material layer ( Figure 7 301, 401).

[0097] The negative electrode and the positive electrode may respectively have a first end portion at which a lug portion is formed and a second end portion opposite to the first end portion.

[0098] The pole ear portion refers to the above-mentioned uncoated portion (the region of the current collector layer where the active material layer is not formed), and this portion may be a portion to which the pole ear is joined in a process such as pole ear welding. In another example, the pole ear portion refers to a portion of the electrode electrically connected to the outside. The uncoated portion may be formed at both ends of the electrode, or may be formed only at one end of the electrode. Figure 81 shows a case where the uncoated portion NC is formed at both ends of the electrode, wherein the active material layers 101 and 102 are formed on both sides of the current collector layer 100. Figure 8 As shown, when uncoated portions are formed at both ends of the electrode, one of the two uncoated portions can be designated as the first end, and the opposite side can be designated as the second end. In one example, a portion to which a tab is attached or to which the tab is electrically connected to the outside by tab welding or the like can be designated as the first end.

[0099] In the electrode assembly, the negative electrode and the positive electrode may be stacked so that the first ends of the negative electrode and the positive electrode are opposite to each other. In another example, the negative electrode and the positive electrode may be stacked so that the first end of either the negative electrode and the positive electrode and the second end of the other are opposite to each other. Here, the situation where any two parts are opposite to each other means that when the first end of the first end of the second ... Figure 4 , Figure 5 and Figure 7 When the electrodes are viewed in the normal direction of the surface of the diaphragm 200 in the structure, these portions overlap, or at least partially overlap.

[0100] In the electrode assembly of the present application having the above structure, a cut portion may be formed in the active material layer of one of the first end and the second end of the negative electrode, and a landslide portion may be formed in the active material layer of the other end. In the negative electrode, a normal thickness region may be formed between the cut portion and the landslide portion.

[0101] The cutting portion refers to a portion formed by making the extension direction of the lateral side of the end of the active material layer in the electrode cross section form an angle within ±5 degrees, ±4 degrees, ±3 degrees, ±2 degrees or ±1 degree with the normal line of the surface of the collector layer, or a portion formed by making the normal line of the surface of the collector layer roughly parallel to the extension direction of the lateral side.

[0102] The cut portion may be formed by a cutting process such as a vertical cut or a slotting process. In this case, the electrode cross section is the same as that in the process of explaining the landslide portion and the normal thickness region.

[0103] As described above, in the electrode that has been subjected to slurry coating, drying and rolling, landslide portions are generally formed at both ends, whereby its cross section presents a similar Fig. 9 That is, Fig. 9 As shown in the example, in the process of coating the slurry on the current collector 100 to form the active material layers 101, 102, due to the characteristics of the slurry, a landslide portion is generated at the starting point and the end point of the coating, that is, along the coating direction or the longitudinal direction of the current collector layer 100 ( Fig. 9 The part with increased or decreased thickness (direction of the double-headed arrow in the figure) Fig. 9 in S).

[0104] By cutting any one of the two ends where the landslide portion is formed by a cutting process such as vertical cutting or slotting, an electrode having one end being the landslide portion and the other end being the cut portion can be formed.

[0105] For example, when following Fig. 9 When cutting in the direction of the dotted line in the one-way arrow direction, such as Fig.10 As shown, an electrode is formed in which one end is a landslide portion and the other end is a cutting portion.

[0106] exist Fig.10 In the electrode, the extension direction of the lateral side 1011 of the active material layer at the end (ie, the cut portion) is substantially parallel to the normal line (the direction of the unidirectional arrow) of the surface of the current collector layer.

[0107] In the electrode assembly of the present application, the active material layers at both ends of the positive electrode may be located at inner positions than the active material layers at both ends of the negative electrode, respectively.

[0108] Here, the active material layers at the two ends of the positive electrode are respectively located at a position closer to the inside than the active material layers at the two ends of the negative electrode, which means that when the electrode assembly is observed in the normal direction of the membrane surface, the negative electrode active material layer extends and is formed more on both ends than the positive electrode active material layer.

[0109] That is to say, Fig.11 or Fig.12 As shown in the exemplary embodiment, when the electrode assembly is observed along the normal direction of the surface of the separator 200, the negative electrode active material layer 301 extends and is formed more along the longitudinal direction of the current collector layers 103 and 104 than the positive electrode active material layer 401. Fig.11 and Fig.12 middle, I 1 and I 2 All are greater than 0. With this arrangement, the phenomenon that the N / P ratio is less than 1 (hereinafter, referred to as the N / P inversion phenomenon) can be effectively prevented.

[0110] In one example, the negative electrode active material layer 301 may be formed to have a larger area than the positive electrode active material layer 401 .

[0111] In one example, in the electrode cross section, the interval ( Fig.11 and Fig.12 I 1 ) and the interval between the positive electrode active material layer 401 and the negative electrode active material layer 301 at the negative terminal where the landslide portion is formed ( Fig.11 and Fig.12 I 2) ratio I 2 / I 1 It can be in the range of 0.5 to 10.

[0112] In another example, the ratio I 2 / I 1 It may be greater than or equal to 1, greater than or equal to 1.5, greater than or equal to 2, greater than or equal to 2.5, greater than or equal to 3, greater than or equal to 4, greater than or equal to 5, greater than or equal to 6, or greater than or equal to 7; or it may be less than or equal to 9, less than or equal to 8, less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2.5, less than or equal to 2, less than or equal to 1.5, or less than or equal to 1, etc. At such a ratio, an electrode assembly that ensures high energy density while effectively preventing the N / P inversion phenomenon can be provided.

[0113] In the electrode assembly, the negative electrode active material layer may also be formed to be thicker than the positive electrode active material layer, thereby providing an electrode assembly that ensures high energy density while effectively preventing the N / P inversion phenomenon. In the above, the thickness of each active material layer is the thickness in the normal thickness region. If the thickness of the normal thickness region is somewhat inconsistent, the relevant thickness refers to the average thickness of the normal thickness region. Although not particularly limited, the thickness T of the negative electrode active material layer N and the thickness T of the positive electrode active material layer P The ratio T N / T P can be greater than 1 and less than or equal to 5. In another example, the ratio T N / T P It can also be less than or equal to 4.5, less than or equal to 4, less than or equal to 3.5, less than or equal to 3, less than or equal to 2.5, less than or equal to 2, or less than or equal to 1.5, and so on.

[0114] In the electrode assembly, a landslide portion can be formed in the active material layer at the end of the positive terminal opposite to the end where the negative electrode cut portion is formed. In this way, an electrode assembly that ensures high energy density while effectively preventing the N / P inversion phenomenon can be provided.

[0115] Fig.11 and Fig.12 2 is a schematic diagram exemplarily showing an electrode assembly having such a shape. The figure shows a case where active material layers 301 and 401 are formed only between current collectors 103 and 104 and separator 200 , but active material layers 301 and 401 may also be formed on opposite lateral sides of each current collector layer 103 and 104 .

[0116] In addition, Fig.11 and Fig.12 In the case of landslide, the inclined surface of the landslide part (e.g., S N , SP The inclined surface may also have a curved shape (e.g., a convex curve or a concave curve, etc.), or other different shapes other than a linear shape.

[0117] Reference Fig.11 and Fig.12 , a cut portion is formed at the right end of the negative electrode active material layer 301, and a landslide portion is formed at the left end, and a landslide portion is formed at the right end of the positive electrode active material layer 401 opposite to the end where the cut portion is formed.

[0118] Fig.11 It is one aspect of the electrode assembly of the present application. In this case, at one end of the positive electrode active material layer 401 ( Fig.11 The above-mentioned landslide portion is formed at the right end portion in the figure, and a cut portion is formed at the opposite end portion of the positive electrode active material layer 401.

[0119] In this structure, the cut portion of the positive electrode active material layer 401 may be located further inward than the landslide portion of the negative electrode active material layer 301 .

[0120] Reference Fig.11 In the structure of , the case where the cut portion of the positive electrode active material layer 401 is located at a position further inward than the landslide portion of the negative electrode active material layer 301 means that the following Formula 1 is satisfied.

[0121] [Formula 1]

[0122] T N / tanθ 1 ≤I 2

[0123] In Formula 1, T N is the thickness of the negative electrode active material layer, that is, the thickness of the normal thickness area of ​​the negative electrode active material layer, θ 1 is the inclination angle of the landslide portion of the negative electrode active material layer, I 2 It is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative electrode end portion where the landslide portion is formed.

[0124] Fig.11 T is shown in N ,θ 1 and I 2 .

[0125] Here, as shown in the figure, to obtain θ 1 The negative electrode active material layer ( Fig.11 The inclined surface S of 301) NThe slope of the landslide portion may have an angle formed by a connecting straight line between the starting point of the landslide portion and the end point of the landslide portion and the longitudinal direction of the current collector layer 103. The actual inclined surface of the landslide portion may be as follows: Fig.11 The linear shape shown can also be other shapes, even if it is not a linear shape, it is based on obtaining θ 1 The shape obtained by the virtual straight line when

[0126] In the above formula 1, T N / tanθ 1 is the width of the landslide portion of the negative electrode active material layer 301, given by Fig.11 W N express.

[0127] By forming the active material layers 301 , 401 to satisfy Formula 1, the electrode assembly may be designed to exhibit high energy density while stably preventing the N / P inversion phenomenon.

[0128] Here, tanθ 1 can have a value in the range of 0.001 to 10. In another example, tanθ 1 It may be greater than or equal to 0.002, greater than or equal to 0.004, greater than or equal to 0.006, greater than or equal to 0.008, greater than or equal to 0.01, greater than or equal to 0.02, greater than or equal to 0.04, greater than or equal to 0.06, greater than or equal to 0.08, greater than or equal to 0.1, greater than or equal to 0.12, greater than or equal to 0.14, greater than or equal to 0.16, greater than or equal to 0.18, or greater than or equal to 0.2; or it may be less than or equal to 9, less than or equal to 8, less than or equal to 7, less than or equal to 0. 6, 5, 4, 3, 2, 1, 0.8, 0.6, 0.4, 0.2, 0.1, 0.08, 0.06, 0.04, 0.02, 0.01, 0.008, 0.006, 0.004, 0.02, 0.01, 0.008, 0.006, 0.004, 0.002, etc.

[0129] Fig.11 The aspect can further satisfy the following formula 2.

[0130] [Formula 2]

[0131] I 2 ≤T N / sinθ 1

[0132] In Formula 2, T N ,θ 1 and I 2 The meaning of is the same as that in Formula 1.

[0133] By further satisfying Formula 2, the expected effect in the present application can be further improved.

[0134] In another aspect of the present application, Fig.12 As shown, at one end of the positive electrode active material layer 401 ( Fig.12 The right end portion of the positive electrode active material layer 401 forms a landslide portion, and the opposite end portion ( Fig.12 The left end portion) can form a second landslide portion.

[0135] In this case, the electrode assembly may be designed to satisfy Formula 3 below.

[0136] [Formula 3]

[0137] T N / tanθ 1 ≤I 2 +T P / tanθ 2

[0138] In Formula 3, T N ,θ 1 and I 2 As defined in Equations 1 and 2, T P is the thickness of the positive electrode active material layer, θ 2 is the inclination angle of the second landslide portion of the positive electrode active material layer.

[0139] Here, the thickness T of the negative electrode active material layer in Formulas 1 and 2 is N Similarly, the thickness of the positive electrode active material layer T P The meaning of is the thickness of the normal thickness region of the positive electrode active material layer. In addition, θ in formulas 1 and 2 can also be obtained according to 1 The inclination angle θ of the second landslide portion of the positive electrode active material layer is obtained by the method 2 .

[0140] The relationship in formula 3 means that Fig.12 I 2 and W P The sum is greater than or equal to W N This relationship is a necessary relationship to achieve the purpose of this application.

[0141] You can Fig.12 The structure is designed to further satisfy the following formula 4.

[0142] [Formula 4]

[0143] I 2 +T P / tanθ 2 ≤T N / sinθ 1

[0144] In Formula 4, T N ,θ 1 ,I 2 、T P and θ 2 has the same meaning as in Formula 3.

[0145] You can also Fig.12 The structure is designed to further satisfy the following formula 5.

[0146] [Formula 5]

[0147] θ 2 / θ 1 >1

[0148] In Formula 5, θ 1 and θ 2 has the same meaning as in Formulas 3 and 4.

[0149] The θ in formula 5 can be formed according to the appropriate proportion 2 / θ 1 For example, θ 2 / θ 1 It can be less than or equal to 5, less than or equal to 4.5, less than or equal to 4, less than or equal to 3.5, less than or equal to 3, less than or equal to 2.5, less than or equal to 2, or less than or equal to 1.5, and so on.

[0150] Through this design, the capacity per unit area of ​​the positive electrode can be maximized while ensuring the capacity relationship between the negative and positive electrodes without N / P inversion.

[0151] As mentioned above, in Fig.11 and Fig.12 In the structure of the electrode assembly, the case where the active material layers 301 and 401 are formed only between the current collectors 103 and 104 and the separator 200 is shown, but the active material layers 301 and 401 may be formed on the opposite sides of the respective current collector layers 103 and 104 .

[0152] For example, in the above structure, the negative electrode may also be included in the current collector layer ( Fig.11 and Fig.12 An active material layer is formed on a lateral side of 103) opposite to the side facing the separator 200.

[0153] In this case, the further included active material layer may be combined with the active material layer present in the current collector layer ( Fig.11 and Fig.12 103) and diaphragm ( Fig.11 and 12 200) between the active material layers ( Fig.11 and Fig.12 301) has a symmetrical structure.

[0154] That is, for example, Fig.10 As shown, when the active material layers 101 and 102 are formed on both sides of the current collector layer 100, the active material layers 101 and 102 may have a symmetrical structure. In this example, the symmetrical structure refers to a substantially symmetrical structure.

[0155] Therefore, in a symmetrical structure, the inclination angle of the landslide portion of the active material layer (e.g. Fig.11 and Fig.12 θ 1 ) or thickness( Fig.11 and Fig.12 T N ) do not necessarily have exactly the same value. For example, when the absolute value of the error in the tilt angle or thickness in the two active material layers is 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less, the two active material layers can be considered to have a symmetrical structure. Here, for example, for thickness, when the thickness of one active material layer is designated as T N1 and the thickness of the other active material layer is designated as T N2 When the calculation error is 100×(T N1 -T N2 ) / T N2 , and the same is true for the tilt angle.

[0156] In the above structure, the positive electrode may further include a current collector layer ( Fig.11 and Fig.12 An active material layer is formed on a lateral side of 104) opposite to the side facing the separator 200.

[0157] In this case, as in the case of the negative electrode, the further included active material layer may be combined with the active material layer present in the current collector layer ( Fig.11 and Fig.12 104) and diaphragm ( Fig.11 and Fig.12 200) between the active material layers ( Fig.11 and Fig.12 401) has a symmetrical structure, wherein the meaning of the symmetrical structure is the same as that of the negative electrode.

[0158] In the present application, the surface of the landslide portion (i.e., the surface of the inclined portion) in the active material layer of the negative electrode or the positive electrode may be a cut surface, i.e., a cut surface. That is, the landslide portion may be a landslide portion naturally generated in the slurry coating process, or may be a landslide portion artificially formed by cutting. When the inclination angle or width ( Fig.11 and Fig.12 W N , W P ,θ 1 ,θ 2 etc.) or the interval between the negative electrode active material layer and the positive electrode active material layer ( Fig.11 and Fig.12 I 1 and I 2 When the above formulas 1 to 5 are not satisfied, a known cutting method can be used to artificially form a landslide portion.

[0159] There is no particular limitation on the method of artificially forming such a landslide portion, and a known etching, cutting, or non-contact cutting (eg, laser cutting) method may be applied.

[0160] Furthermore, in the electrode assembly of the present application, there is no particular limitation on materials forming the current collector, the active material layer, and the like, and the structure may be formed using known materials.

[0161] In addition, there is no limitation on the manufacturing method, and the electrode assembly can be constructed by manufacturing the electrode using a known manufacturing method, and if necessary, the above-mentioned etching, cutting or non-contact cutting process can also be performed on the electrode formed by the known manufacturing method.

[0162] The present application also relates to a secondary battery or an electrochemical element including an electrode assembly and an electrolyte.

[0163] If the electrode assembly of the present application is applied, there is no particular limitation on the material constituting the secondary battery or the electrochemical element, and known materials may be used.

Claims

1. An electrode assembly, comprising: Negative electrode, positive electrode and separator, wherein the negative electrode and the positive electrode are stacked and the separator is inserted between the negative electrode and the positive electrode, The negative electrode and the positive electrode respectively include a current collector layer and an active material layer at least located between the current collector layer and the separator. The negative electrode and the positive electrode respectively have a first end portion formed with a pole ear portion and a second end portion opposite to the first end portion. wherein the negative electrode and the positive electrode are stacked in a manner that their first ends face each other, or in a manner that the first end of one of the negative electrode and the positive electrode faces the second end of the other of the negative electrode and the positive electrode, wherein a cutting portion is formed in the active material layer at one of the first end and the second end of the negative electrode, and a landslide portion is formed in the active material layer at the other of the first end and the second end of the negative electrode, The active material layers at the two ends of the positive electrode are respectively located closer to the inside than the active material layers at the two ends of the negative electrode. Among them, the ratio I2 / I1 of the interval I2 between the positive electrode active material layer and the negative electrode active material layer at the negative end forming the landslide portion to the interval I1 between the positive electrode active material layer and the negative electrode active material layer at the negative end forming the cut portion is in the range of 0.5 to 10.

2. The electrode assembly according to claim 1, wherein: The negative electrode active material layer is thicker than the positive electrode active material layer.

3. The electrode assembly according to claim 1, wherein: A landslide portion is formed in the active material layer of the positive terminal portion opposite to the negative terminal portion where the cut portion is formed.

4. The electrode assembly according to claim 3, wherein: The surface of the landslide portion of the positive electrode active material layer is a cut surface.

5. The electrode assembly according to claim 3, wherein: A cut portion is formed in the positive electrode active material layer at an end portion opposite to an end portion where the landslide portion of the positive electrode active material layer is formed.

6. The electrode assembly according to claim 5, wherein: The cut portion of the positive electrode active material layer is located more inner than the landslide portion of the negative electrode active material layer.

7. The electrode assembly according to claim 5, satisfying the following formula 1: [Formula 1] T N / tanθ1≤I2 in, T N is the thickness of the negative electrode active material layer, θ1 is the inclination angle of the landslide portion of the negative electrode, and I2 is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative end portion where the landslide portion is formed.

8. The electrode assembly according to claim 7, wherein: tanθ1 is in the range of 0.001 to 10.

9. The electrode assembly according to claim 7 further satisfies the following formula 2: [Formula 2] I2≤T N / sinθ1 in, T N is the thickness of the negative electrode active material layer, θ1 is the inclination angle of the landslide portion of the negative electrode, and I2 is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative end portion where the landslide portion is formed.

10. The electrode assembly according to claim 3, wherein: A second landslide portion is formed in the positive electrode active material layer at an end portion opposite to an end portion where the landslide portion of the positive electrode active material layer is formed.

11. The electrode assembly according to claim 10, wherein: The surface of the second landslide portion of the positive electrode active material layer is a cut surface.

12. The electrode assembly according to claim 10, satisfying the following formula 3: [Formula 3] T N / tanθ1≤I2+T P / tanθ2 in, T N is the thickness of the negative electrode active material layer, θ1 is the inclination angle of the landslide portion of the negative electrode, I2 is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative end portion forming the landslide portion, T P is the thickness of the positive electrode active material layer, and θ2 is the inclination angle of the second landslide portion of the positive electrode.

13. The electrode assembly according to claim 12 further satisfies the following formula 4: [Formula 4] I2+T P / tanθ2≤T N / sinθ1 in, T N is the thickness of the negative electrode active material layer, θ1 is the inclination angle of the landslide portion of the negative electrode, I2 is the interval between the positive electrode active material layer and the negative electrode active material layer at the negative end portion forming the landslide portion, T P is the thickness of the positive electrode active material layer, and θ2 is the inclination angle of the second landslide portion of the positive electrode.

14. The electrode assembly according to claim 10, satisfying the following formula 5: [Formula 5] θ2 / θ1>1 in, θ1 is the inclination angle of the landslide portion of the negative electrode, and θ2 is the inclination angle of the second landslide portion of the positive electrode.

15. The electrode assembly according to claim 1, wherein: The negative electrode further includes an active material layer formed on a surface of the current collector layer opposite to a surface of the current collector layer facing the separator.

16. The electrode assembly according to claim 15, wherein: The active material layer formed on the surface of the current collector layer opposite to the surface of the current collector layer facing the separator and the active material layer between the current collector layer and the separator have a symmetrical structure.

17. The electrode assembly according to claim 1, wherein: The positive electrode further includes an active material layer formed on a surface of the current collector layer opposite to a surface of the current collector layer facing the separator.

18. The electrode assembly according to claim 17, wherein: The active material layer formed on the surface of the current collector layer opposite to the surface of the current collector layer facing the separator and the active material layer between the current collector layer and the separator have a symmetrical structure.

19. A secondary battery comprising: The electrode assembly according to any one of claims 1 to 18; as well as Electrolytes.

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