Electrode assembly and battery cell comprising same

Abstract

The present disclosure relates to an electrode assembly and a battery cell comprising the same, in an electrode assembly according to one embodiment of the present disclosure, an electrode and a separator provided on the electrode are wound in a roll form, the electrode includes a current collector, an active material layer formed on the current collector, and an uncoated portion in which the active material layer is not formed, the uncoated portion including a plurality of flag portions formed at predetermined intervals from each other, the plurality of flag portions being bent in a central axis direction in which the electrode is wound to form a bent portion, the flag portions provided in the same winding circle do not overlap each other when bent, and an interval (Dm) between the flag portions provided in the same winding circle satisfies a specific condition.

Description

Technical Field

[0001] This disclosure relates to an electrode assembly and a battery cell including the electrode assembly, specifically, to an electrode assembly with excellent stability and a battery cell including the electrode assembly. Background Technology

[0002] A rechargeable battery is a type of battery that converts electrical energy into chemical energy and stores it, allowing it to be reused multiple times through charging and discharging. Rechargeable batteries are widely used across various industries due to their economic and environmentally friendly characteristics. In particular, lithium-ion batteries are widely used in various industries, including portable devices requiring high-density energy.

[0003] The working principle of a lithium-ion rechargeable battery is an electrochemical redox reaction. That is, it's a principle that generates electricity through the movement of lithium ions, and charges through the reverse process. In a lithium-ion rechargeable battery, the phenomenon of lithium ions escaping from the negative electrode (Anode) and moving to the positive electrode (Cathode) through the electrolyte and separator is called discharging. The process that is the reverse of this phenomenon is called charging.

[0004] Secondary batteries are manufactured by assembling multiple components; in particular, electrodes can be welded to the casing or electrode current collector. Welding quality is a crucial factor determining the performance of secondary batteries; therefore, much research is underway to improve welding quality. Summary of the Invention

[0005] (a) Technical problems to be solved One embodiment of this disclosure provides an electrode assembly with low internal resistance and high energy density, and a battery cell including the electrode assembly.

[0006] One embodiment of this disclosure provides an electrode assembly with excellent contact with a current collector and a battery cell including the electrode assembly.

[0007] One embodiment of this disclosure provides an electrode assembly with excellent weldability and a battery cell including the electrode assembly.

[0008] On the other hand, the battery casing and cells disclosed herein can be widely used in electric vehicles, battery charging stations, energy storage systems (ESS), and other green technologies such as solar power generation and wind power generation that utilize batteries. Furthermore, the battery components disclosed herein can be used in eco-friendly transportation vehicles, including electric vehicles and hybrid vehicles, to prevent climate change by suppressing air pollution and greenhouse gas emissions.

[0009] (II) Technical Solution One embodiment of this disclosure provides an electrode assembly in which an electrode and a diaphragm disposed on the electrode are wound in a roll configuration. The electrode includes a current collector, an active material layer formed on the current collector, and an uncoated portion without the active material layer. The uncoated portion includes a plurality of flag portions formed at predetermined intervals between each other. The plurality of flag portions are bent toward the central axis of the electrode winding to form a bent portion. During bending, the flag portions disposed in the same winding loop do not overlap each other, and the interval (Dm) between the flag portions disposed in the same winding loop satisfies the following formula 1. [Formula 1] Dm1≤Dm≤2.5*Dm1, In Equation 1, , Dm is the spacing between flags in the m-th winding, Rm is the radius of curvature of the m-th winding, H is the height of the flag in the m-th winding, B is the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 are the sizes of the interior angles of the lower part of the flag in the m-th winding.

[0010] In one embodiment, in the electrode assembly, the number of flags disposed on the outer peripheral surface of the winding from the center axis of the winding can be gradually increased within the same winding loop.

[0011] In one embodiment, the electrode assembly may satisfy Equation 2. [Equation 2] D m ≥(2πR m -B m xU nn ) / U nn , In Equation 2, D mR is the spacing between the flags in the m-th winding turn. m B is the radius of curvature of the m-th winding. m U is the length of the bottom edge of the flag section in the m-th winding loop. nn It represents the number of flags placed in the m-th winding loop.

[0012] In one embodiment, the number of flag portions included in the m-th winding and the (m+1)-th winding can be the same, and the length (B) of the bottom edge of the flag portion included in the m-th winding and the (m+1)-th winding can be the same.

[0013] In one embodiment, the electrode assembly is an electrode assembly that satisfies the following formula 3. [Formula 3] θ≤90°-(180° / (2πRm / Bm), In Equation 3, θ is θ1 or θ2, θ1 and θ2 are the sizes of the interior angles of the lower part of the flag portion in the m-th winding loop, θ1 and θ2 can be the same or different, Bm is the length of the bottom edge of the flag portion in the m-th winding loop, and Rm is the radius of curvature of the m-th winding loop.

[0014] In one embodiment, the overlapping area formed by the bend of any flag portion in the m-th winding loop and the bend of the flag portion in the (m+1)-th winding loop can be 20% to 95% of the total area of ​​one side of the bend of any flag portion in the m-th winding loop.

[0015] One embodiment of this disclosure provides a battery cell, the battery cell comprising: an electrode assembly, electrodes and a separator disposed on the electrodes wound in a roll shape, the electrodes comprising a current collector, an active material layer formed on the current collector, and an uncoated portion without the active material layer; and a housing for accommodating the electrode assembly, wherein the uncoated portion comprises a plurality of flag portions formed at predetermined intervals, the plurality of flag portions being bent toward the central axis of the electrode winding to form a bent portion, wherein the flag portions disposed in the same winding do not overlap each other during bending, and the interval (Dm) between the flag portions disposed in the same winding satisfies the following formula 1. [Formula 1] Dm1≤Dm≤2.5*Dm1, In Equation 1, , Dm is the spacing between flags in the m-th winding, Rm is the radius of curvature of the m-th winding, H is the height of the flag in the m-th winding, B is the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 are the sizes of the interior angles of the lower part of the flag in the m-th winding.

[0016] In one embodiment, the housing may include: a housing body including an opening for receiving the electrode assembly; and a cover plate for covering the housing body.

[0017] In one embodiment, the battery cell may include a current collector electrically connected to the bent portion of the flag.

[0018] In one embodiment, the bent portion of the flag and the current collector can be joined by welding.

[0019] In one embodiment, in the electrode assembly, the number of flags disposed on the outer peripheral surface of the same winding coil, starting from the center axis of the winding coil, can be gradually increased.

[0020] (III) Beneficial Effects An electrode assembly and a battery cell including the electrode assembly according to an embodiment of the present disclosure can have excellent durability and high energy density.

[0021] An electrode assembly according to an embodiment of the present disclosure can have excellent contact with the current collector. Additionally, an electrode assembly according to an embodiment of the present disclosure can have excellent weldability and electrolyte impregnation properties.

[0022] According to one embodiment of this disclosure, the electrodes of the electrode assembly can form flat bends between adjacent uncoated portions without interference, thereby exhibiting excellent weldability and contact with the current collector.

[0023] According to one embodiment of this disclosure, the electrodes of the electrode assembly can maximize the contact area with the current collector and form flat bends between adjacent uncoated portions without interference, thereby exhibiting excellent weldability and contact with the current collector. Therefore, by increasing the weld strength, internal resistance can be reduced, thereby providing a cell with increased energy density. Furthermore, by adjusting the overlap ratio of the bends, excellent electrolyte impregnation properties can be achieved. Attached Figure Description

[0024] Figure 1 This is a schematic perspective view of a battery cell according to one embodiment.

[0025] Figure 2 This is a schematic cross-sectional view of a battery cell according to one embodiment.

[0026] Figure 3 This is a schematic exploded perspective view of a battery cell according to one embodiment.

[0027] Figure 4 This is a schematic diagram illustrating an electrode assembly according to one embodiment.

[0028] Figure 5 This is a schematic diagram illustrating electrodes according to one embodiment.

[0029] Figure 6 This is a schematic diagram showing a portion of the electrodes.

[0030] Figure 7 This is a schematic diagram illustrating the bent state of a flag according to one embodiment.

[0031] Figures 8 to 10 This is a schematic diagram showing one side of an electrode assembly according to one embodiment. Detailed Implementation

[0032] The present disclosure will now be described in detail with reference to the accompanying drawings. However, these are merely examples, and the present disclosure is not limited to the specific embodiments described herein.

[0033] The specific terminology used in this specification is for illustrative purposes only and is not intended to limit the embodiments shown.

[0034] For example, expressions such as "same" and "identical" not only indicate a state of strict sameness, but also indicate a state of difference in tolerance or degree of achieving the same functionality.

[0035] For example, expressions such as "any direction", "along any direction", "parallel", "perpendicular", "centered", "concentric" or "coaxial" indicate relative or absolute arrangement. They not only indicate an arrangement that is strictly so, but also indicate a state of relative displacement with tolerances or to achieve the same degree of functionality at angles or distances.

[0036] To illustrate this disclosure, the following explanation is based on an orthogonal spatial coordinate system in which the X, Y, and Z axes are orthogonal to each other. Each axis (X-axis direction, Y-axis direction, Z-axis direction) represents the two directions on which each axis extends.

[0037] The X, Y, and Z directions described below are for illustrative purposes to provide a clearer understanding of this disclosure. Of course, each direction may be defined differently depending on the reference datum.

[0038] The use of terms such as "first," "second," and "third" before the components described below is solely to avoid confusion and is unrelated to the order, importance, or hierarchical relationship between the components. For example, it is also possible to implement an invention that includes only the second component without the first component.

[0039] The terminology used in this disclosure is for illustrative purposes only and is not intended to limit the scope of the claims. As used in the description of the embodiments and in the appended claims, the singular form includes the plural form unless the context clearly indicates otherwise.

[0040] Figure 1 This is a schematic perspective view of a battery cell according to one embodiment. Figure 2 This is a schematic cross-sectional view of a battery cell according to one embodiment. Figure 3 This is a schematic exploded perspective view of a battery cell according to one embodiment. Figure 4 This is a schematic diagram illustrating an electrode assembly according to one embodiment.

[0041] Reference Figures 1 to 4 According to one embodiment of the present disclosure, the battery cell 100 may include an electrode assembly 200 and a housing 110, 120 for accommodating the electrode assembly.

[0042] In one embodiment, the housings 110 and 120 may comprise various metals such as iron and aluminum, as well as alloys of combinations thereof, plastics, ceramics, or carbon. In one embodiment, the housing may be carbon steel with a nickel (Ni) or tin (Sn) plating formed on its surface. Alternatively, in one embodiment, it may be hypoeutectoid steel with a carbon content of less than 0.8% wt. Or, it may be stainless steel containing chromium (Cr).

[0043] In one embodiment, the battery cell 100 may include electrode terminals 130 formed on the housings 110 and 120 and electrically connected to the built-in electrode assembly 200.

[0044] The electrode assembly 200 may include a first electrode and a second electrode, as well as a diaphragm disposed between the first electrode and the second electrode.

[0045] In one embodiment, the cell 100 may further include an electrolyte. For example, the electrolyte may be a medium for transferring ions or current between a first electrode (positive electrode) and a second electrode (negative electrode) of the electrode assembly 200.

[0046] In one embodiment, the battery cell 100 can be a secondary battery capable of multiple charging and discharging cycles. For example, the secondary battery can be one of the following: lithium cobalt battery, lithium high-nickel battery, lithium iron phosphate battery, lithium-ion battery, lithium polymer battery, lithium sulfur battery, nickel-metal hydride battery, nickel-cadmium battery, sodium battery, or all-solid-state battery, but is not limited to these, and can be modified into various types of secondary batteries.

[0047] In one embodiment, refer to Figures 1 to 3The housing may include a housing body 110 having an opening 114 and an opposing surface 111 facing the opening, and a cover plate 120 covering the opening 114. The electrode assembly 200 can be inserted into the housing body 110 through the opening 114.

[0048] The cover plate 120 can enclose the housing body 110. After the electrode assembly 200 is housed inside the housing body 110, the cover plate 120 can be attached to the housing body 110. After the cover plate 120 is attached to the housing body 110, the housing can be sealed by welding or other means.

[0049] In one embodiment, the shell body 110 may be cylindrical. However, this is only one embodiment, and the shape of the shell body 110 may be deformed into various shapes such as prisms and hexahedrons.

[0050] In one embodiment, the battery cell 100 may include a housing body 110, a cover plate 120, an electrode assembly 200, a current collector 140, electrode terminals 130, and an insulating gasket.

[0051] In one embodiment, the electrode assembly 200 may include a first electrode, a second electrode, and a diaphragm. The current collector 140 may include at least one of a first current collector 141 and a second current collector 142. The first current collector 141 may be disposed between the opposite surface 111 of the housing body 110 and the electrode assembly 200. The second current collector 142 may be disposed between the cover plate 120 and the electrode assembly 200.

[0052] Current collectors 141 and 142 can be electrically connected to the electrodes of the electrode assembly 200. Specifically, they can be electrically connected to the bent portion of the flag of the electrode assembly 200. Details of this will be explained later. For this purpose, current collector 140 can be made of conductive materials such as copper, gold, silver, or aluminum.

[0053] In one embodiment, the first current collector 141 and the second current collector 142 may be electrically connected to different electrodes of the electrode assembly 200. For example, the first current collector 141 may be connected to a first electrode, and the second current collector 142 may be electrically connected to a second electrode. In another embodiment, the first current collector 141 may be electrically connected to electrode terminal 130. The second current collector 142 may be electrically connected to housing body 110 and / or cover plate 120.

[0054] In one embodiment, the electrode terminal 130 may be formed on the opposing surface 111. Specifically, it may be located on the side opposite the cover plate 120 in the height direction (e.g., the Z-axis direction). The electrode terminal 130 may be electrically connected to the first current collector 141 and exposed to the outside through the opposing surface 111, and may be electrically connected to an external device. That is, current can flow to the external device through the electrode terminal 130.

[0055] In one embodiment, a first insulating washer 135 may be provided between the housing body 110 and the electrode terminal 130. The first insulating washer 135 may contain an insulating material. The insulating material may contain materials with low conductivity, such as polymers or ceramics.

[0056] In one embodiment, electrode terminals (not shown) may be formed in the cover plate 120. A second insulating gasket 136 may be provided between the cover plate 120 and the housing body 110, which can block the electrical connection between the cover plate 120 and the housing body 110.

[0057] Alternatively, separate electrode terminals may not be formed on the cover plate 120; the cover plate 120 itself may be electrically connected to the electrode assembly 200 to perform the function of an electrode terminal.

[0058] In one embodiment, the electrode terminals 130 located on the housing body 110 and the housing 110 can have different polarities. For example, if the polarity of the electrode terminal 130 is (+), then the polarity of the housing body 110 can be (-). In this case, the polarity of the cover plate 120 can be (-). That is, an insulating gasket may not be provided between the cover plate 120 and the housing body 110, and the cover plate 120 and the housing body 110 can be electrically connected to have the same polarity. For example, if the polarity of the electrode terminal 130 is (+), then the polarity of the housing body 110 and the cover plate 120 can be (-).

[0059] In one embodiment, when the electrode assembly 200 is inserted into the housing body 110, it can be inserted through the opening 114 so that the first current collector 141 faces the opposing surface 111. Then, the second current collector 142 can be inserted into the housing body 110.

[0060] In one embodiment, the step of electrically connecting the current collector 140 and the electrode assembly 200 can be performed. The method of electrically connecting the current collector 140 and the electrode assembly 200 is not particularly limited; for example, it can be performed by welding, and the welding method can be ultrasonic welding or laser welding.

[0061] In one embodiment, the electrode assembly 200 can have excellent weldability and contact with the current collector 140. The electrode assembly 200 can have a flat bend for connection with the current collector 140. In one embodiment, the bend of the flag formed by bending the electrode assembly 200 can be the current collector 140. Therefore, it can have excellent weldability and contact with the current collector 140.

[0062] In one embodiment, the battery cell may include: an electrode assembly, an electrode and a separator disposed on the electrode wound in a roll, the electrode including a current collector, an active material layer formed on the current collector, and an uncoated portion without the active material layer; and a housing for accommodating the electrode assembly.

[0063] In the electrode assembly, the uncoated portion may include a plurality of flag portions formed at predetermined intervals between each other. The plurality of flag portions are bent toward the central axis of the electrode winding to form a bent portion. When bent, the flag portions arranged in the same winding do not overlap each other, and the interval Dm between the flag portions arranged in the same winding can satisfy the following formula 1.

[0064] [Formula 1] Dm1≤Dm≤2.5*Dm1, , In Equation 1, Dm is the spacing between flag sections in the m-th winding loop, Rm is the radius of curvature in the m-th winding loop, H is the height of the flag section in the m-th winding loop, B is the length of the bottom edge of the flag section in the m-th winding loop, and θ1 and θ2 are the sizes of the interior angles of the lower part of the flag section in the m-th winding loop.

[0065] Hereinafter, an electrode assembly 200 according to one embodiment will be described.

[0066] In one embodiment, electrode assembly 200 may include electrodes and a diaphragm.

[0067] Figure 4 This is a schematic diagram illustrating an electrode assembly 200 according to one embodiment. Figure 5 This is a schematic diagram illustrating electrodes according to one embodiment. Figure 6 This is a schematic diagram showing a portion of the electrodes. Figure 7 This is a schematic diagram illustrating the bent state of the flag portion according to one embodiment.

[0068] like Figure 4 As shown, the electrode assembly 200 can be in the form of a wound roll. Figure 4 The image shows a portion of the wound electrode assembly 200 being disassembled.

[0069] In one embodiment, the electrode assembly 200 can be wound along a central axis A in a stacked state of first electrode 20, diaphragm 250, and second electrode 30. The central axis A can be in the height direction (e.g., the Z-axis direction).

[0070] In addition, not limited to this, in one embodiment, the electrode assembly 200 may be plate-shaped or prismatic.

[0071] Reference Figure 5 According to one embodiment, the first electrode 20 may include a current collector 210, an active material layer 220 formed on the current collector 210, and an uncoated portion 230 adjacent to the active material layer 220. In one embodiment, the first electrode 20 may include a current collector 210, an active material layer 220 formed on the current collector 210, and an uncoated portion 230 where the active material layer 220 is not formed. That is, the region in the current collector 210 where the active material layer 220 is not formed can be understood as the uncoated portion 230.

[0072] The current collector 210 may contain a conductive material known in the range that does not cause a chemical reaction within the lithium secondary battery. For example, the current collector 210 may contain any one of stainless steel, nickel (Ni), aluminum (Al), titanium (Ti), copper (Cu), and alloys thereof, and may be provided in various forms such as film, sheet, and foil.

[0073] Alternatively, in one embodiment, the uncoated portion may be a region separately attached to the current collector 210 on which the active material layer 220 is formed, and may contain a conductive material known not to cause a chemical reaction within the lithium secondary battery.

[0074] The first electrode 20 can be understood as the first electrode. In the same manner as the first electrode, the second electrode 30 may also include a current collector 310, an active material layer 320 formed on the current collector 310, and an uncoated portion 330 adjacent to the active material layer 320.

[0075] The following explanation focuses on the first electrode 20, but the second electrode 30 can also be understood in the same way.

[0076] Reference Figure 4 and Figure 6 The uncoated portion 230 may include a plurality of flag portions 231, 232 formed at predetermined intervals between each other.

[0077] The plurality of flags 231, 232 can be formed by cutting a portion of the uncoated region in the current collector where no electrode active material layer has been formed. However, this is not a limitation; for example, a region of the uncoated portion can be cut using known metal cutting processes such as welding, ultrasonic welding, or stamping to form a plurality of flags 231, 232 with specific shapes and spacing. In one embodiment, the thickness of the uncoated portion can be less than 20 μm, and the height of the uncoated portion can be less than 7000 μm. A portion of the uncoated portion in the height direction can be bent to form a bent portion (…). Figure 7 L).

[0078] In one embodiment, a plurality of flags 231, 232 may be arranged along the winding direction DR of the electrode assembly 200. That is, the electrode may include a plurality of flags 231, 232 arranged along the winding direction DR.

[0079] In one embodiment, the first electrode 20 and the second electrode 30 may include a plurality of flags 231, 232 arranged along the winding direction DR. The flags formed on the first electrode 20 and the second electrode 30 during the formation of the wound can be arranged to face opposite directions. With reference to the height direction (z-direction), the flags 231, 232 of the first electrode 20 can be arranged facing upwards, and the flags 331, 332 of the second electrode 30 can be arranged facing downwards.

[0080] In one embodiment, a plurality of flag portions 231, 232 may be formed on one side end of the first electrode 20. The flag portions 231, 232 have a predetermined width and may be formed at a predetermined interval D between them.

[0081] In one embodiment, the lower width of each of the flag portions 231 and 232 may be greater than the upper width. The lower width of the flag portion can be understood as the length B of the bottom edge of the flag portion, and the upper width of the flag portion can be understood as the length U of the top edge of the flag portion.

[0082] In one embodiment, the flag portions 231 and 232 may be trapezoidal in shape. Alternatively, the flag portions 231 and 232 may be rectangular, parallelogram-shaped, semicircular, semi-elliptical, or other similar shapes.

[0083] In one embodiment, the width of the flag portions and the spacing D between the flag portions disposed in the same winding loop can be substantially the same. "Substantially the same" means that it can include design errors, and includes not only cases where the deviation of the spacing D between the flag portions is 0%, but also cases where the deviation is less than 10%.

[0084] Specifically, the flag portions 231a and 232a included in the m-th turn may have substantially the same width and substantially the same spacing D, and the flag portions 231b and 232b included in the (m+1)-th turn may have substantially the same width and substantially the same spacing D. In one embodiment, the electrode assembly may be wound 40 to 70 times, and is not limited thereto.

[0085] In another embodiment, the interior angles θ1 and θ2 of the lower part of the flag portions 231a and 232a included in the m-th ring may have substantially the same size as each other.

[0086] like Figure 7As shown, the plurality of flag portions 210 can be bent toward the central axis A, that is, the core portion C.

[0087] When the flag portions 231c and 232c are bent, they can overlap with the flag portions 231b and 232b that are set in the previous winding loop.

[0088] When the flag portions 231b and 232b in the (m+1)th winding loop are bent, they can overlap with the flag portions 231a and 232a in the mth winding loop.

[0089] In one embodiment, the flag portion in the (m+1)th winding is bent to overlap with the flag portion located in the mth winding, and the overlapping area formed by the bent portion of the flag portion in the mth winding and the bent portion of the flag portion in the (m+1)th winding can be 20% to 95% of the total area of ​​one side of the bent portion of the flag portion in the mth winding.

[0090] In one embodiment, the area ratio of the overlapping region can be based on any one of the flags set in the m-th winding loop.

[0091] In one embodiment, the area ratio of the overlapping region can be based on the flag portion as a whole set in the m-th winding loop.

[0092] Reference Figure 7 Multiple flag portions 231a, 231b, and 231c can be bent toward the central axis C of the electrode winding to form a bent portion, and the overlapping areas L1 and L2 formed by the bent portion of the flag portion 231b in the m-th winding and the bent portion of the flag portion 231b in the (m+1)-th winding can be 20% to 95% of the area of ​​the bent portion of the flag portion.

[0093] In one embodiment, the overlapping area L2 formed by the bend L of any flag portion 231b in the m-th winding loop and the bend of any flag portion 231c in the (m+1)-th winding loop can be 20% to 95% of the total area of ​​the bend L of any flag portion 231b in the m-th winding loop. The total area of ​​the bend L of any flag portion 231b can be based on the side facing the bend of the flag portion in the (m+1)-th winding loop.

[0094] According to one embodiment, the electrodes of the electrode assembly can maximize the contact area with the current collector and form flat bends between adjacent flags without interference, thereby having excellent weldability and contact with the current collector.

[0095] The bent portions formed by bending the plurality of flag sections 210 can be electrically connected to the current collector plate 140. However, this is not a limitation; the current collector plate 140 and the bent portions can be connected by welding. However, this is not a limitation; the welding method for joining the plurality of flag sections 210 to the current collector plate 140 can be ultrasonic welding or laser welding.

[0096] According to one embodiment of this disclosure, when the flag portions disposed in the same winding coil do not overlap each other, and the overlap area of ​​the bent portions of the flag portions is 20% to 95%, the contact with the current collector is good, thereby allowing for good welding. Therefore, the electrode will have low resistance, thereby increasing energy density. In one embodiment, the overlap area of ​​the bent portions of the flag portions can be 50% to 95%. When the overlap area of ​​the bent portions of the flag portions is less than 20%, the electrode connectivity decreases, potentially reducing charging and discharging efficiency. Furthermore, when the overlap area of ​​the bent portions of the flag portions exceeds 95%, the contact with the current collector decreases, potentially increasing resistance. Additionally, when the overlap area of ​​the bent portions of the flag portions exceeds 95%, the electrolyte is difficult to move during electrolyte injection, potentially reducing the impregnation properties of the electrolyte.

[0097] Figures 8 to 10 This is a schematic diagram showing one side of an electrode assembly according to one embodiment.

[0098] Specifically, Figures 8 to 10 This is a diagram illustrating various arrangements of the flag section according to one embodiment.

[0099] Reference Figure 8 In one embodiment, the number of flag portions 231, 232 included in the m-th winding turn (the same winding turn) can gradually increase from the central axis of the winding turn, i.e., the core portion C, toward the outer peripheral surface O.

[0100] In one embodiment, when the length B of the bottom edge of the flag portion 231 is formed in the same way, and the spacing D between the flag portions is formed in the same way, the number of flag portions 231 and 232 in the winding of the outer peripheral surface O can be greater than the number of flag portions 231 and 232 in the winding of the core portion C because the radius of curvature on the outer peripheral surface becomes larger.

[0101] In one embodiment, adjacent flag portions 231, 232 in the same winding loop can be formed so that they do not overlap.

[0102] In one embodiment, adjacent flag portions 231 and 232 in the same winding loop can be formed so that they do not overlap. In this case, the spacing D between the flag portions... m It can satisfy Equation 2 below.

[0103] [Equation 2] D m ≥(2πR m-B m xU nn ) / U nn , In Equation 2, D m R is the spacing between the flags in the m-th winding turn. m B is the radius of curvature in the m-th winding. m U is the length of the bottom edge of the flag section in the m-th winding loop. nn It represents the number of flags in the m-th winding loop.

[0104] As described above, in one embodiment, adjacent flag portions 231 and 232 in the same winding loop can be formed so as not to overlap each other. In this case, the interval Dm between the flag portions in the m-th winding loop can satisfy the following equation 1.

[0105] [Formula 1] Dm1≤Dm≤2.5*Dm1, In Equation 1, , Dm is the spacing between flags in the m-th winding, Rm is the radius of curvature in the m-th winding, H is the height of the flag in the m-th winding, B is the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 are the sizes of the interior angles of the lower part of the flag in the m-th winding.

[0106] In Equation 1, Dm1 is the minimum interval between flags that do not overlap. The characters defined in Equation 1 can be found by referring to... Figure 6 and Figure 8 Let me explain.

[0107] When the flags arranged in the same winding do not overlap each other, and the spacing between the flags is the same as, or less than 2.5 times the minimum spacing Dm1, the contact between the bent portion of the flag and the current collector is good, thereby improving weldability. Therefore, excellent weld strength is exhibited, thus improving battery durability. Additionally, due to low resistance, energy density can be increased. When the spacing between the flags is greater than 2.5 times the minimum spacing Dm1, weldability decreases, potentially reducing strength. When the spacing between the flags is less than the minimum spacing Dm1, electrolyte movement is difficult during electrolyte injection, potentially reducing electrolyte impregnation and possibly decreasing battery production efficiency.

[0108] In one embodiment, the electrode assembly can satisfy Equation 3. That is, the sizes θ1 and θ2 of the lower interior angles of the flag portion included in the m-th ring can satisfy Equation 3.

[0109] [Formula 3] θ≤90°-(180° / (2πRm / Bm) In Equation 3, θ is θ1 or θ2, where θ1 and θ2 are the sizes of the interior angles of the lower part of the flag in the m-th winding, and they can be the same or different. Bm is the length of the bottom edge of the flag in the m-th winding, and Rm is the radius of curvature of the m-th winding.

[0110] As described above, by adjusting the width of the flag (the length of the bottom edge B of the flag and the length of the top edge U of the flag), the spacing D between the flags, and the size of the inner angles θ1 and θ2 at the bottom of the flags 231 and 232, the position of the flag in each winding loop and the structure of the overall bending part of the flag can be adjusted.

[0111] Reference Figure 9 In one embodiment, the interval D between the flag portions 231 and 232 can gradually increase from the central core portion C to the outer peripheral surface (Dm+1>Dm).

[0112] In one embodiment, the number of flag portions included in the m-th winding turn and the (m+1)-th winding turn can be the same, and the length B of the bottom edge of the flag portion included in the m-th winding turn and the (m+1)-th winding turn can be the same.

[0113] In one embodiment, when the number of flag portions included in the m-th winding and the (m+1)-th winding are formed in the same way, and the lengths of the bottom edges of the flag portions in the m-th winding and the (m+1)-th winding are formed in the same way, the interval Dm+1 between the flag portions in the (m+1)-th winding can be greater than the interval Dm between the flag portions in the m-th winding.

[0114] In one embodiment, the position of the flag in each winding loop can be adjusted by adjusting the width of the flag (the length of the bottom edge B of the flag and the length of the top edge U of the flag) and the spacing D between the flags.

[0115] In one embodiment, the electrode assembly 200 may satisfy the following equation 4.

[0116] [Formula 4] Bm / Rm=Bm+1 / Rm+1 In Equation 4, Bm is the length of the bottom edge of the flag section in the m-th winding, and Rm is the radius of curvature of the m-th winding.

[0117] Reference Figure 10When the number of flag portions included in the m-th winding loop and the (m+1)-th winding loop are formed in the same way, and the lower interior angles θ1 and θ2 of the flag portions 231 and 232 included in the m-th winding loop and the (m+1)-th winding loop have the same size, and satisfy Equation 4, the overall shape of the bent flag portion can have a tapered shape.

[0118] According to one embodiment, the electrodes of the electrode assembly 200 are formed by bending the flag portion of the uncoated portion to form a bent portion, and the bent portion can be electrically connected to the current collector 140.

[0119] According to one embodiment, by adjusting the width of the flag portion, the spacing D between the flag portions, and the size of the inner angles θ1 and θ2 of the lower portions of the flag portions 231 and 232, a flat, non-interfering bend between adjacent uncoated portions can be formed. Therefore, excellent weldability and contact with the current collector 140 can be achieved. By improving the weldability and contact with the electrode assembly 200 and the current collector 140, the internal resistance of the battery cell can be reduced, and the energy density of the battery cell can be increased. Furthermore, by adjusting the ratio of the overlapping areas of the flag portions, the movement of the electrolyte during injection becomes easier, thereby improving the impregnation properties of the electrolyte.

[0120] The present invention will now be described in more detail through an embodiment of the present invention, but these embodiments do not limit the scope of the present invention.

[0121] Manufacturing example The minimum spacing Dm1 between the flags was calculated using the conditions in Table 1 below, and the electrode assembly was manufactured using the conditions in Table 2 below with reference to this. The Dm1 in Table 2 has the same value as the Dm1 recorded in Table 1.

[0122] [Table 1]

[0123] [Table 2]

[0124] [evaluate] 1. Weldability Evaluation After the electrode assembly manufactured above was welded to the current collector, the weld strength was measured. The weld strength measurement was performed by vertically pulling the current collector plate until it broke after the electrode assembly was welded to the current collector. The results are shown in Table 3 below.

[0125] 2. Electrolyte impregnation properties The electrode assembly welded to the current collector was immersed in DMC solution to impregnate it with the electrolyte. The degree of impregnation was measured by disassembling the electrode assembly to allow for complete impregnation. Disassembly was performed in 1-hour increments before 12 hours of electrolyte impregnation, and in 6-hour increments after 12 hours, to determine the completion time of impregnation. The results are shown in Table 3 below.

[0126] [Table 3]

[0127] Referring to Table 3, compared with the comparative example, it can be confirmed that by maximizing the contact area between the electrode and the current collector, excellent welding strength with the current collector is achieved, and by adjusting the spacing between the flags, excellent electrolyte impregnation is achieved.

[0128] Specifically, in Examples 1 to 4, a weld strength of 30 kgf or more was observed, thus indicating excellent battery durability. However, in Comparative Examples 1 to 5, the weld strength was less than 30 kgf, thus indicating lower battery durability. Furthermore, in Examples 1 to 4, the electrolyte was rapidly impregnated for less than 12 hours. In Comparative Examples 1 to 3, the interval between the flags was too small, resulting in an electrolyte impregnation time far exceeding 12 hours. Since electrolyte impregnation needs to be completed before 12 hours to ensure production efficiency, the production efficiency of Comparative Examples 1 to 3 is expected to be low. Additionally, Comparative Examples 4 and 5 had faster electrolyte impregnation times but lower weld strength, thus potentially resulting in excellent production efficiency, but lower battery durability. In other words, according to one embodiment of this disclosure, sufficient weld strength can be ensured while achieving a shorter impregnation time.

[0129] The following is a description of various aspects of this disclosure.

[0130] First aspect: An electrode assembly can be provided in which an electrode and a diaphragm disposed on the electrode are wound in a roll form. The electrode includes a current collector, an active material layer formed on the current collector, and an uncoated portion where the active material layer is not formed. The uncoated portion includes a plurality of flag portions formed at predetermined intervals from each other. The plurality of flag portions are bent toward the central axis of the electrode winding to form a bent portion. When bent, the flag portions disposed in the same winding do not overlap each other, and the interval Dm between the flag portions disposed in the same winding can satisfy the following formula 1.

[0131] [Formula 1] Dm1≤Dm≤2.5*Dm1, Furthermore, in Equation 1, , Dm can be the spacing between flags in the m-th winding, Rm can be the radius of curvature of the m-th winding, H can be the height of the flag in the m-th winding, B can be the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 can be the size of the interior angles of the lower part of the flag in the m-th winding.

[0132] Second aspect: According to the first aspect, an electrode assembly in which the number of flags disposed in the same winding coil gradually increases from the central axis of the winding coil to the outer peripheral surface can be provided.

[0133] Third aspect: According to the first or second aspect, an electrode assembly satisfying Formula 2 can be provided.

[0134] [Equation 2] D m ≥(2πR m -B m xU nn ) / U nn , Furthermore, in Equation 2, D m It can be the spacing between flags in the m-th winding turn, R m It can be the radius of curvature of the m-th winding, B m It can be the length of the bottom edge of the flag portion in the m-th winding loop, U nn This can be the number of flags set in the m-th winding loop.

[0135] Fourth aspect: According to any one of the first to third aspects, an electrode assembly can be provided in which the number of flag portions included in the m-th winding and the (m+1)-th winding are the same, and the length B of the bottom edge of the flag portions included in the m-th winding and the (m+1)-th winding are the same.

[0136] Fifth aspect: According to any one of the first to fourth aspects, an electrode assembly satisfying Formula 3 can be provided.

[0137] [Formula 3] θ≤90°-(180° / (2πRm / Bm), Additionally, in Equation 3, θ can be θ1 or θ2, θ1 and θ2 can be the size of the interior angle of the lower part of the flag portion in the m-th winding loop, they can be the same or different, and Bm can be the length of the bottom edge of the flag portion in the m-th winding loop, and Rm can be the radius of curvature of the m-th winding loop.

[0138] Sixth aspect: According to any one of the first to fifth aspects, an electrode assembly can be provided in which the overlapping area formed by the bend of any flag portion in the m-th winding and the bend of the flag portion in the (m+1)-th winding is 20% to 95% of the total area of ​​one side of the bend of any flag portion in the m-th winding.

[0139] Seventh aspect: According to any one of the first to sixth aspects, a battery cell can be provided, the battery cell comprising: an electrode assembly, an electrode and a separator disposed on the electrode wound in a roll form, the electrode comprising a current collector, an active material layer formed on the current collector, and an uncoated portion without the active material layer; and a housing for accommodating the electrode assembly, the uncoated portion comprising a plurality of flag portions formed at predetermined intervals from each other, the plurality of flag portions being bent toward the central axis of the electrode winding to form a bend portion, wherein the flag portions disposed in the same winding do not overlap each other during bending, and the interval Dm between the flag portions disposed in the same winding can satisfy the following formula 1.

[0140] [Formula 1] Dm1≤Dm≤2.5*Dm1, Furthermore, in Equation 1, , Dm can be the spacing between flags in the m-th winding, Rm can be the radius of curvature of the m-th winding, H can be the height of the flag in the m-th winding, B can be the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 can be the size of the interior angles of the lower part of the flag in the m-th winding.

[0141] Eighth aspect: According to any one of the first to seventh aspects, a battery cell can be provided, wherein the housing includes a housing body having an opening for receiving the electrode assembly and a cover plate covering the housing body.

[0142] Ninth aspect: According to any one of the first to eighth aspects, a cell comprising a current collector electrically connected to the bent portion of the flag portion can be provided.

[0143] Tenth aspect: According to any one of the first to ninth aspects, a battery cell can be provided in which the bent portion of the flag and the current collector are joined by welding.

[0144] Eleventh aspect: According to any one of the first to tenth aspects, a battery cell can be provided, wherein the number of flags disposed in the same winding in the electrode assembly gradually increases from the central axis of the winding to the outer peripheral surface.

[0145] This disclosure can be implemented in various forms, and its scope of rights is not limited to the embodiments described above. Therefore, if a modified embodiment includes components within the scope of the claims of this disclosure, it should be considered to fall within the scope of this disclosure.

Claims

1. An electrode assembly, wherein, An electrode and a diaphragm disposed on the electrode are wound in a roll shape. The electrode includes a current collector, an active material layer formed on the current collector, and an uncoated portion where the active material layer is not formed. The uncoated portion includes a plurality of flag portions formed at predetermined intervals between each other. These flag portions are bent toward the central axis of the electrode winding to form a bent portion. During bending, the flag portions disposed in the same winding loop do not overlap each other, and the interval (Dm) between the flag portions disposed in the same winding loop satisfies the following formula 1. [Formula 1] Dm1≤Dm≤2.5*Dm1, In Equation 1, ， Dm is the spacing between flags in the m-th winding, Rm is the radius of curvature of the m-th winding, H is the height of the flag in the m-th winding, B is the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 are the sizes of the interior angles of the lower part of the flag in the m-th winding.

2. The electrode assembly according to claim 1, wherein, The number of flags arranged in the same winding loop gradually increases from the center axis of the winding roll to the outer peripheral surface.

3. The electrode assembly according to claim 1, wherein, The electrode assembly satisfies the following formula 2. [Equation 2] D m ≥(2πR m -B m xU nn ) / U nn , In Equation 2, D m R is the spacing between the flags in the m-th winding turn. m B is the radius of curvature of the m-th winding. m U is the length of the bottom edge of the flag section in the m-th winding loop. nn It represents the number of flags placed in the m-th winding loop.

4. The electrode assembly according to claim 1, wherein, The number of flag portions included in the m-th winding and the (m+1)-th winding are the same, and the length (B) of the bottom edge of the flag portions included in the m-th winding and the (m+1)-th winding are the same.

5. The electrode assembly according to claim 1, wherein, The electrode assembly satisfies the following formula 3. [Formula 3] θ≤90°-(180° / (2πRm / Bm), In Equation 3, θ is either θ1 or θ2, where θ1 and θ2 are the sizes of the interior angles at the bottom of the flag portion in the m-th winding loop. θ1 and θ2 may be the same or different. Bm is the length of the bottom edge of the flag section in the m-th winding loop. Rm is the radius of curvature of the m-th winding.

6. The electrode assembly according to claim 1, wherein, The overlapping area formed by the bend of any flag in the m-th winding and the bend of the flag in the (m+1)-th winding is 20% to 95% of the total area of ​​one side of the bend of any flag in the m-th winding.

7. A battery cell, comprising: An electrode assembly, an electrode, and a diaphragm disposed on the electrode are wound in a roll form. The electrode includes a current collector, an active material layer formed on the current collector, and an uncoated portion where the active material layer is not formed. as well as Housing for accommodating the electrode assembly. The uncoated portion includes a plurality of flag portions formed at predetermined intervals between each other. These flag portions are bent toward the central axis of the electrode winding to form a bent portion. During bending, the flag portions disposed in the same winding loop do not overlap each other, and the interval (Dm) between the flag portions disposed in the same winding loop satisfies the following formula 1. [Formula 1] Dm1≤Dm≤2.5*Dm1, In Equation 1, ， Dm is the spacing between flags in the m-th winding, Rm is the radius of curvature of the m-th winding, H is the height of the flag in the m-th winding, B is the length of the bottom edge of the flag in the m-th winding, and θ1 and θ2 are the sizes of the interior angles of the lower part of the flag in the m-th winding.

8. The battery cell according to claim 7, wherein, The housing includes: The housing body includes an opening for receiving the electrode assembly; and A cover plate is used to cover the main body of the housing.

9. The battery cell according to claim 7, comprising: The collector plate is electrically connected to the bent portion of the flag.

10. The battery cell according to claim 9, wherein, The bent part of the flag and the collector plate are joined together by welding.

11. The battery cell according to claim 7, wherein, From the center axis of the winding coil outwards, the number of flags disposed in the same winding coil in the electrode assembly gradually increases.

Images