Electrode assembly and battery cell including same

Abstract

The present disclosure relates to an electrode assembly and a battery cell including same. The electrode assembly according to an embodiment of the present disclosure may comprise an electrode and a separator which are wound in a roll shape, the electrode including: a current collector; an active material layer formed on the current collector; and a non-coated part on which the active material layer is not formed, the separator being disposed on the electrode, wherein the non-coated part includes a plurality of flags formed at a predetermined interval from each other, the plurality of flags are bent in the direction of the central axis around which the electrode is wound, so as to form a bent part, the flags arranged in the same winding turn do not overlap each other when bent, and the interval (Dm) between the flags arranged in the same winding turn satisfies a specific condition.

Description

Electrode assembly and battery cell including the same

[0001] The present disclosure relates to an electrode assembly and a battery cell including the same, and more particularly, to an electrode assembly having excellent stability and a battery cell including the same.

[0002] Secondary batteries convert electrical energy into chemical energy, allowing them to be stored and reused multiple times through charging and discharging. Due to their economical and environmentally friendly properties, secondary batteries are widely used across various industries. Lithium secondary batteries, in particular, are widely used in portable devices requiring high energy density, as well as in various industries.

[0003] Lithium secondary batteries operate on an electrochemical redox reaction. That is, electricity is generated through the movement of lithium ions, and the reverse process is used to charge the battery. In lithium secondary batteries, the phenomenon in which lithium ions leave the anode and migrate through the electrolyte and separator to the cathode is called discharging. The reverse process is called charging.

[0004] Secondary batteries are manufactured by assembling multiple components. Specifically, electrodes can be welded to a housing or electrode collector. Weld quality is a critical factor in determining secondary battery performance, and extensive research is being conducted to improve it.

[0005] One embodiment of the present disclosure provides an electrode assembly having low internal resistance and high energy density and a battery cell including the same.

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

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

[0008] Meanwhile, the battery case and battery cell according to the present disclosure can be widely applied in green technology fields such as electric vehicles, battery charging stations, energy storage systems (ESS), and other battery-based photovoltaics and wind power generation. In addition, the battery assembly according to the present disclosure can be used in eco-friendly mobility, including electric vehicles and hybrid vehicles, to prevent climate change by suppressing air pollution and greenhouse gas emissions.

[0009] One embodiment of the present disclosure is an electrode including a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; wound in a roll shape,

[0010] The above-mentioned non-conductive part includes a plurality of flags formed at a predetermined interval from each other, and the plurality of flags are bent in the direction of the central axis along which the electrode is wound to form a bent part, and when bent, the flags arranged in the same winding turn do not overlap each other, and an electrode assembly is provided in which the interval (Dm) between the flags arranged in the same winding turn satisfies the following equation 1.

[0011] [Formula 1]

[0012] Dm1 ≤ Dm ≤ 2.5*Dm1

[0013] In the above equation 1,

[0014] , and Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 are the sizes of the lower interior angles of the flags in the mth winding turn.

[0015] In one embodiment, the electrode assembly may have an increasing number of flags arranged in the same winding turn as it moves from the central axis of the winding roll to the outer circumference.

[0016] In one embodiment, the electrode assembly may satisfy Equation 2 below.

[0017] [Formula 2]

[0018] D m ≥(2πR m -B m ×U nn ) / U nn

[0019] In the above equation 2,

[0020] D m is the spacing between flags placed in the mth winding turn, and R m is the radius of curvature at the mth winding turn, and B m is the length of the base of the flag of the mth winding turn, and U nn is the number of flags placed in the mth winding turn.

[0021] In one embodiment, the number of flags included in the m-th winding turn and the m+1-th winding turn may be the same, and the lengths (B) of the bases of the flags included in the m-th winding turn and the m+1-th winding turn may be the same.

[0022] In one embodiment, the electrode assembly is an electrode assembly satisfying the following equation 3;

[0023] [Formula 3]

[0024] θ≤90°-(180° / (2πRm / Bm)

[0025] In the above equation 3,

[0026] θ is θ1 or θ2, and θ1 and θ2 are the sizes of the lower inner angles of the flags arranged in the mth winding turn, which may be equal or different,

[0027] Bm is the length of the base of the flag placed in the mth winding turn,

[0028] Rm is the radius of curvature of the mth winding turn.

[0029] In one embodiment, the overlapping area of ​​the flag bending portion of the (m+1)th winding turn with the flag bending portion of the (m+1)th winding turn in any one of the flag bending portions arranged in the mth winding turn may be 20 to 95% of the total area of ​​one side of any one of the flag bending portions arranged in the mth winding turn.

[0030] One embodiment of the present disclosure provides a battery cell including: an electrode including a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; an electrode assembly wound in a roll shape; and a case accommodating the electrode assembly; wherein the non-conductive portion includes a plurality of flags formed at a predetermined interval from each other, and the plurality of flags are bent in the direction of a central axis along which the electrode is wound to form a bent portion, and when bent, flags disposed in the same winding turn do not overlap each other, and a gap (Dm) between flags disposed in the same winding turn satisfies the following equation 1.

[0031] [Formula 1]

[0032] Dm1 ≤ Dm ≤ 2.5*Dm1

[0033] In the above equation 1,

[0034] , and Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 are the sizes of the lower interior angles of the flags in the mth winding turn.

[0035] In one embodiment, the case may include a case body including an opening for accommodating the electrode assembly and a cap plate covering the case body.

[0036] In one embodiment, the battery cell may include a current collector electrically connected to the flag fold.

[0037] In one embodiment, the flag bending portion and the collector plate may be joined by welding.

[0038] In one embodiment, the electrode assembly may have an increasing number of flags arranged in the same winding turn as it moves from the central axis of the winding roll to the outer circumference.

[0039] An electrode assembly according to one embodiment of the present disclosure and a battery cell including the same may have excellent durability and high energy density.

[0040] An electrode assembly according to one embodiment of the present disclosure may have excellent contact with a current collector. In addition, an electrode assembly according to one embodiment of the present disclosure may have excellent weldability and electrolyte impregnation properties.

[0041] According to one embodiment of the present disclosure, the electrode of the electrode assembly can form a flat folded portion without interference between adjacent non-conductive portions, and thus can have excellent weldability and contactability with the current collector plate.

[0042] According to one embodiment of the present disclosure, the electrode of the electrode assembly can secure a maximum contact area with the current collector plate while forming a flat folded portion without interference between adjacent non-coated portions, thereby achieving excellent weldability and contactability with the current collector plate. Accordingly, the welding strength can be improved, thereby reducing internal resistance and providing a battery cell with improved energy density. Furthermore, the ratio of the overlapping area of ​​the folded portion can be adjusted to improve electrolyte impregnation properties.

[0043] FIG. 1 is a perspective view schematically illustrating a battery cell according to one embodiment.

[0044] FIG. 2 is a cross-sectional view schematically showing a cross-section of a battery cell according to one embodiment.

[0045] FIG. 3 is an exploded perspective view schematically illustrating a battery cell according to one embodiment.

[0046] Figure 4 is a schematic drawing showing an electrode assembly according to one embodiment.

[0047] Figure 5 is a schematic diagram showing an electrode according to one embodiment.

[0048] Figure 6 is a drawing schematically showing a part of an electrode.

[0049] FIG. 7 is a drawing schematically showing a state in which a flag is bent according to one embodiment.

[0050] FIGS. 8 to 10 are schematic drawings showing one side of an electrode assembly according to one embodiment.

[0051] Hereinafter, the present disclosure will be described in detail with reference to the attached drawings. However, these are merely exemplary and the present disclosure is not limited to the specific embodiments described as examples.

[0052] Certain terms used in this specification are for convenience of explanation only and are not intended to limit the illustrated embodiments.

[0053] For example, expressions such as "same" and "same as" not only indicate a strictly identical state, but also indicate a state in which there is a difference in tolerance, or the degree to which the same function is obtained.

[0054] For example, expressions indicating relative or absolute arrangements such as “in which direction,” “along which direction,” “parallel,” “perpendicular,” “centered,” “concentric,” or “coaxial” not only strictly indicate such arrangements, but also indicate a state of relative displacement with an angle or distance that allows for tolerance, or the degree to which the same function is obtained.

[0055] In order to explain the present disclosure, the following description is based on a spatial orthogonal coordinate system with mutually orthogonal X-axis, Y-axis, and Z-axis. Each axis direction (X-axis direction, Y-axis direction, Z-axis direction) means both directions in which each axis extends.

[0056] The X-direction, Y-direction, and Z-direction mentioned below are for the purpose of explanation so that the present disclosure can be clearly understood, and it is of course possible to define each direction differently depending on where the standard is set.

[0057] The use of terms such as "first," "second," and "third" before the components mentioned below is intended solely to avoid confusion regarding the components they refer to, and has no bearing on the order, importance, or dominant-subordinate relationship between the components. For example, an invention can be implemented that includes only a second component without a first component.

[0058] The terminology used in this disclosure is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise.

[0059] FIG. 1 is a perspective view schematically showing a battery cell according to one embodiment, FIG. 2 is a cross-sectional view schematically showing a cross-section of a battery cell according to one embodiment, FIG. 3 is an exploded perspective view schematically showing a battery cell according to one embodiment, and FIG. 4 is a drawing schematically showing an electrode assembly according to one embodiment.

[0060] Referring to FIGS. 1 to 4, a battery cell according to one embodiment of the present disclosure (100) may include an electrode assembly (200) and a case (110, 120) that accommodates the electrode assembly.

[0061] In one embodiment, the case (110, 120) may include various metals such as iron, aluminum, alloys thereof, plastic, ceramic, or materials such as carbon. In one embodiment, the case may be carbon steel having a plating layer such as nickel or tin formed on the surface. In addition, in one embodiment, the case may be hypoeutectoid steel having carbon of 0.8% wt or less. Alternatively, the case may be stainless steel including chromium, etc.

[0062] In one embodiment, the battery cell (100) is formed in the case (110, 120) and may include an electrode terminal (130) electrically connected to the built-in electrode assembly (200).

[0063] The above electrode assembly (200) may include a first electrode, a second electrode, and a separator disposed between the first and second electrodes.

[0064] In one embodiment, the battery cell (100) may further include an electrolyte. The electrolyte may be, for example, a medium that transfers ions or current between the first electrode (anode) and the second electrode (cathode) of the electrode assembly (200).

[0065] In one embodiment, the battery cell (100) may be a secondary battery capable of being charged and discharged multiple times. For example, the secondary battery may be one of a lithium cobalt battery, a lithium high-nickel battery, a lithium iron phosphate battery, a lithium ion battery, a lithium polymer battery, a lithium sulfur battery, a nickel hydrogen battery, a nickel cadmium battery, a sodium battery, and an all-solid-state battery, but is not limited thereto and may be modified into various types of secondary batteries.

[0066] In one embodiment, referring to FIGS. 1 to 3, the case may include a case body (110) having an opening (114) and an opposing surface (111) facing the opening, and a cap plate (120) covering the opening (114). The electrode assembly (200) may be inserted into the case body (110) through the opening (114).

[0067] The cap plate (120) can close the case body (110). After the electrode assembly (200) is accommodated inside the case body (110), the cap plate (120) can be coupled to the case body (110). The cap plate (120) can be coupled to the case body (110) and the case can be sealed by welding or the like.

[0068] In one embodiment, the shape of the case body (110) may be cylindrical. However, this is only one embodiment, and the shape of the case body (110) may be modified into various shapes such as a square or a hexahedron.

[0069] In one embodiment, the battery cell (100) may include a case body (110), a cap plate (120), an electrode assembly (200), a current collector plate (140), an electrode terminal (130), and an insulating gasket.

[0070] In one embodiment, the electrode assembly (200) may include a first electrode, a second electrode, and a separator. The current collector plate (140) may include at least one of a first current collector plate (141) and a second current collector plate (142). The first current collector plate (141) may be disposed between the facing surface (111) of the case body (110) and the electrode assembly (200). The second current collector plate (142) may be disposed between the cap plate (120) and the electrode assembly (200).

[0071] The current collector plate (141, 142) may be electrically connected to the electrode of the electrode assembly (200). Specifically, it may be electrically connected to the flag bending portion of the electrode assembly (200). Details thereof will be described later. For this purpose, the current collector plate (140) may include a conductive material such as copper, gold, silver, or aluminum.

[0072] In one embodiment, the first collector plate (141) and the second collector plate (142) may be electrically connected to different electrodes of the electrode assembly (200). For example, the first collector plate (141) may be connected to the first electrode, and the second collector plate (142) may be connected to the second electrode. In an embodiment, the first collector plate (141) may be electrically connected to the electrode terminal (130). The second collector plate (142) may be electrically connected to the case body (110) and / or the cap plate (120).

[0073] In one embodiment, the electrode terminal (130) may be formed on the opposite surface (111). Specifically, it may be positioned on the opposite side in the height direction (e.g., Z-axis direction) from the cap plate (120). The electrode terminal (130) is electrically connected to the first current collector plate (141), may be exposed to the outside by penetrating the opposite surface (111), and may be electrically connected to an external device. That is, current may flow to the external device through the electrode terminal (130).

[0074] In one embodiment, a first insulating gasket (135) may be placed between the case body (110) and the electrode terminal (130). The first insulating gasket (135) may include an insulating material. The insulating material may include a material with low electrical conductivity, such as a polymer or ceramic.

[0075] In one embodiment, an electrode terminal may be formed on the cap plate (120) (not shown). A second insulating gasket (136) may be placed between the cap plate (120) and the case body (110), and may block the electrical connection between the cap plate (120) and the case body (110).

[0076] Alternatively, a separate electrode terminal may not be formed on the cap plate (120), and the cap plate (120) itself may be electrically connected to the electrode assembly (200) to serve as an electrode terminal.

[0077] In one embodiment, the electrode terminal (130) located on the case body (110) and the case body (110) may have different polarities. For example, if the polarity of the electrode terminal (130) is (+), the polarity of the case body (110) may be (-). At this time, the polarity of the cap plate (120) may be (-). That is, an insulating gasket is not disposed between the cap plate (120) and the case body (110), and the cap plate (120) and the case body (110) may be electrically connected to each other and have the same polarity. For example, if the polarity of the electrode terminal (130) is (+), the polarities of the case body (110) and the cap plate (120) may be (-).

[0078] In one embodiment, when inserting the electrode assembly (200) into the case body (110), the electrode assembly (200) may be inserted into the case body (110) through the opening (114) so ​​that the first collector plate (141) faces the opposite surface (111). Thereafter, the second collector plate (142) may be inserted into the case body (110).

[0079] In one embodiment, a step of electrically connecting the current collector plate (140) and the electrode assembly (200) may be performed. The method of electrically connecting the current collector plate (140) and the electrode assembly (200) is not particularly limited, but may be performed by, for example, welding, and the welding method may be ultrasonic welding or laser welding.

[0080] In one embodiment, the electrode assembly (200) may have excellent weldability and contactability with the current collector plate (140). The electrode assembly (200) may have a flat folded portion for connection with the current collector plate (140). In one embodiment, the flag folded portion formed by folding the electrode assembly (200) may be the current collector plate (140). Accordingly, the weldability and contactability with the current collector plate (140) may be excellent.

[0081] In one embodiment, the battery cell may include an electrode including a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; an electrode assembly in which the electrode assembly is wound in a roll shape; and a case accommodating the electrode assembly.

[0082] In the above electrode assembly, the non-conductive portion includes a plurality of flags formed at a predetermined interval from each other, and the plurality of flags are bent in the direction of the central axis along which the electrode is wound to form a bent portion, and when bent, flags arranged in the same winding turn do not overlap each other, and the interval (Dm) between flags arranged in the same winding turn can satisfy the following equation 1.

[0083] [Formula 1]

[0084] Dm1 ≤ Dm ≤ 2.5*Dm1

[0085]

[0086] In the above equation 1,

[0087] Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 are the sizes of the lower interior angles of the flags in the mth winding turn.

[0088] Hereinafter, an electrode assembly (200) according to one embodiment will be described.

[0089] In one embodiment, the electrode assembly (200) may include an electrode and a separator.

[0090] Fig. 4 is a schematic drawing of an electrode assembly (200) according to one embodiment. Fig. 5 is a schematic drawing of an electrode according to one embodiment, and Fig. 6 is a schematic drawing of a portion of the electrode. Fig. 7 is a schematic drawing of a state in which a flag is bent according to one embodiment.

[0091] As illustrated in Fig. 4, the electrode assembly (200) may be in the form of a rolled roll. Fig. 4 illustrates a state in which a portion of the rolled electrode assembly (200) is disassembled.

[0092] In one embodiment, the electrode assembly (200) can be wound along a central axis (A) while the first electrode (20), the separator (250), and the second electrode (30) are stacked. Here, the central axis (A) can be in the height direction (e.g., the Z-axis direction).

[0093] Additionally, and not limited thereto, in one embodiment, the electrode assembly (200) may be plate-shaped or square-shaped.

[0094] Referring to FIG. 5, a first electrode (20) according to one embodiment may include a current collector (210); an active material layer (220) formed on the current collector (210); and a non-conductive region (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 a non-conductive region (230) on which the active material layer (220) is not formed. That is, a region of the current collector (210) on which the active material layer (220) is not formed may be understood as a non-conductive region (230).

[0095] The current collector (210) may include a known conductive material within a range that does not cause a chemical reaction within a lithium secondary battery. For example, the current collector (210) may include 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 a film, a sheet, or a foil.

[0096] Alternatively, in one embodiment, the non-conductive portion may be a region separately attached to the current collector (210) on which the active material layer (220) is formed, and may include a known conductive material within a range that does not cause a chemical reaction within the lithium secondary battery.

[0097] The above first electrode (20) can be understood as a first electrode, and the second electrode (30) can also include a current collector (310) and an active material layer (320) formed on the current collector (310) and a non-conductive portion (330) adjacent to the active material layer (320) in the same manner as the first electrode.

[0098] Hereinafter, the description will focus on the first electrode (20), but the second electrode (30) can also be understood in the same manner.

[0099] Referring to FIGS. 4 and 6, the non-conductive portion (230) may include a plurality of flags (231, 232) formed at a predetermined interval from each other.

[0100] The plurality of flags (231, 232) may be formed by cutting a portion of a non-coated region of the current collector where an electrode active material layer is not formed. Although not limited thereto, for example, a plurality of flags (231, 232) having a specific shape and spacing may be formed by cutting a portion of the non-coated region through a known metal cutting process such as a laser, ultrasonic, or punching. In one embodiment, the thickness of the non-coated region may be 20 μm or less, and the height of the non-coated region may be 7,000 μm or less. A portion of the height of the non-coated region may be bent to form a bent portion (L of FIG. 7).

[0101] 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).

[0102] 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). When forming the winding roll, the flags formed on the first electrode (20) and the second electrode (30) may be arranged to face in opposite directions. With respect to the height direction (z direction), the flags (231, 232) of the first electrode (20) may be arranged to face upward, and the flags (331, 332) of the second electrode (30) may be arranged to face downward.

[0103] In one embodiment, a plurality of flags (231, 232) may be formed on one end of the first electrode (20), and the flags (231, 232) may have a predetermined width and be formed at a predetermined interval (D) from each other.

[0104] In one embodiment, each of the flags (231, 232) may have a lower width greater than an upper width. The width of the lower portion of the flag may be understood as the length (B) of the flag's base, and the width of the upper portion of the flag may be understood as the length (U) of the flag's upper portion.

[0105] In one embodiment, the flags (231, 232) may have a trapezoidal shape. Alternatively, the flags (231, 232) may have a shape such as a square, a equilateral triangle, a semicircle, or a semi-ellipse.

[0106] In one embodiment, the widths of flags arranged in the same winding turn and the spacing between flags (D) may be substantially equal. "Substantially equal" may include design errors, and may include not only cases where the deviation in the spacing between flags (D) is 0%, but also cases where the deviation is 10% or less.

[0107] Specifically, the flags (231a, 232a) included in the mth turn may have substantially the same width and substantially the same spacing (D), and the flags (231b, 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, but may not be limited thereto.

[0108] Additionally, in one embodiment, the lower inner angles (θ1, θ2) of the flags (231a, 232a) included in the mth turn may have substantially the same size.

[0109] As illustrated in FIG. 7, the plurality of flags (210) can be bent toward the central axis (A), i.e., the core portion (C).

[0110] When the above flags (231c, 232c) are bent, they can overlap with the flags (231b, 232b) placed in the preceding gunshot.

[0111] When the flags (231b, 232b) of the m+1th winding turn are bent, they can overlap with the flags (231a, 232a) arranged in the mth winding turn.

[0112] In one embodiment, the flag of the (m+1)th winding turn is bent and overlaps with the flag located at the m-th winding turn, and the overlapping area by the flag bending portion of the (m+1)th winding turn in the flag bending portion arranged at the m-th winding turn may be 20 to 95% of the total area of ​​one side of the flag bending portion arranged at the m-th winding turn.

[0113] In one embodiment, the area ratio of the overlapping region may be based on any one flag placed in the mth winding turn.

[0114] In one embodiment, the area ratio of the overlapping region may be based on the entire flag placed in the mth winding turn.

[0115] Referring to FIG. 7, a plurality of flags (231a, 231b, 231c) can be bent in the direction of the central axis (C) along which the electrode is wound to form a bent portion, and an overlapping area (L1, L2) by the bent portion of the flag (231b) of the (m+1)th winding turn in the bent portion of the flag (231b) arranged in the mth winding turn can be 20 to 95% of the area of ​​the flag bent portion.

[0116] In one embodiment, the overlapping area (L2) formed by the bend portion (L) of any one flag (231b) arranged in the m-th winding turn and the bend portion of any one flag (231c) arranged in the m+1-th winding turn may be 20 to 95% of the total area of ​​the bend portion (L) of any one flag (231b) arranged in the m-th winding turn. The total area of ​​the bend portion (L) of any one flag (231b) may be based on one surface toward which the bend portion of the flag arranged in the m+1-th winding turn faces.

[0117] According to one embodiment, the electrode of the electrode assembly may have a flat folded portion that secures a maximum contact area with the current collector plate while preventing interference between adjacent flags, thereby providing excellent weldability and contactability with the current collector plate.

[0118] The folded portion formed by bending the plurality of flags (210) may be electrically connected to the collector plate (140). Although not limited thereto, the collector plate (140) and the folded portion may be connected by welding. Although not limited thereto, the welding method for joining the plurality of flags (210) to the collector plate (140) may be ultrasonic welding or laser welding.

[0119] According to one embodiment of the present disclosure, when flags arranged in the same winding turn do not overlap each other and the overlapping area of ​​the flag bending portion is 20 to 95%, the contact with the collector plate can be improved, so that welding can be performed well. Accordingly, the electrode resistance can be low, and the energy density can be improved. In one embodiment, the overlapping area of ​​the flag bending portion can be 50 to 95%. If the overlapping area of ​​the flag bending portion is less than 20%, the connectivity of the electrodes can be reduced, which can lower the charge / discharge efficiency. In addition, if the overlapping area of ​​the flag bending portion exceeds 95%, the contact with the collector plate can be reduced, which can increase the resistance. In addition, if the overlapping area of ​​the flag bending portion exceeds 95%, the movement of the electrolyte can be difficult during electrolyte injection, which can lower the electrolyte impregnation property.

[0120] FIGS. 8 to 10 are schematic drawings showing one side of an electrode assembly according to one embodiment.

[0121] Specifically, FIGS. 8 to 10 are drawings showing various arrangement methods of flags according to one embodiment.

[0122] Referring to FIG. 8, in one embodiment, the number of flags (231, 232) included in the m-th winding turn (same winding turn) may increase from the core portion (C), which is the center axis of the winding roll, toward the outer circumference (O).

[0123] In one embodiment, when the length (B) of the base of the flag (231) is formed to be the same and the spacing (D) between the flags is formed to be the same, the radius of curvature at the outer surface becomes larger, so the number of flags (231, 232) in the winding turns of the outer surface (O) may be greater than the number of flags (231, 232) in the winding turns of the core portion (C).

[0124] In one embodiment, flags (231, 232) adjacent to each other in the same winding turn can be formed so as not to overlap each other.

[0125] In one embodiment, flags (231, 232) adjacent to each other in the same winding turn can be formed so as not to overlap each other. At this time, the gap between the flags (D m ) can satisfy the following equation 1.

[0126] [Formula 2]

[0127] D m ≥(2πR m -B m xU nn ) / U nn

[0128] In the above equation 2,

[0129] D m is the spacing between flags in the mth winding turn, and R m is the radius of curvature at the mth winding turn, and B m is the length of the flag base in the mth winding turn, and U nn is the number of flags in the mth winding turn.

[0130] As described above, in one embodiment, adjacent flags (231, 232) in the same winding turn can be formed so as not to overlap each other. At this time, the spacing (Dm) between flags arranged in the mth winding turn can satisfy the following equation 1.

[0131] [Formula 1]

[0132] Dm1 ≤ Dm ≤ 2.5*Dm1

[0133] In the above equation 1,

[0134] , and Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 are the sizes of the lower interior angles of the flags in the mth winding turn.

[0135] In the above equation 1, Dm1 is the minimum spacing between flags that do not overlap, and the characters defined in equation 1 can be interpreted with reference to FIGS. 6 and 8.

[0136] If the flags arranged in the same winding turn do not overlap each other and the gap between the flags is equal to the minimum gap (Dm1) at which the flags do not overlap or is formed to be 2.5 times or less of the minimum gap (Dm1), the contact between the flag bending part and the collector plate is good, which can improve the weldability. Accordingly, the excellent welding strength can be exhibited, which can improve the durability of the battery. In addition, the energy density can be improved because it has low resistance. If the minimum gap (Dm1) is greater than 2.5 times, the weldability may be deteriorated, which can lower the strength, and if it is smaller than the minimum gap, the movement of the electrolyte may be difficult during electrolyte injection, which may lower the electrolyte impregnation property, and the battery productivity may be lowered.

[0137] In one embodiment, the electrode assembly may satisfy Equation 3 below. That is, the size (θ1, θ2) of the lower inner angle of the flag included in the mth turn may satisfy Equation 3 below.

[0138] [Formula 3]

[0139] θ≤90°-(180° / (2πRm / Bm)

[0140] In the above equation 3,

[0141] θ is θ1 or θ2, and θ1 and θ2 are the sizes of the lower inner angles of the flags arranged in the mth winding turn, which may be equal or different,

[0142] Bm is the length of the base of the flag placed in the mth winding turn,

[0143] Rm is the radius of curvature of the mth winding turn.

[0144] In this way, by adjusting the width of the flag (flag bottom length (B), flag top length (U)), the spacing between flags (D), and the size of the lower inner angle (θ1, θ2) of the flags (231, 232), the position of the flag at each winding turn and the overall folded structure of the flag can be adjusted.

[0145] Referring to FIG. 9, in one embodiment, the spacing (D) between flags (231, 232) may become larger as it goes from the central core portion (C) to the outer periphery (Dm+1>Dm).

[0146] In one embodiment, the number of flags included in the m-th winding turn and the m+1-th winding turn may be the same, and the lengths (B) of the bases of the flags included in the m-th winding turn and the m+1-th winding turn may be the same.

[0147] In one embodiment, when the number of flags included in the m-th winding turn and the m+1-th winding turn are formed to be the same, and the length (Bm) of the bottom of the flag located in the m-th winding turn and the length (Bm+1) of the bottom of the flag located in the m+1-th winding turn are formed to be the same, the interval (Dm+1) between the flags located in the m+1-th winding turn may be greater than the interval (Dm+1) between the flags located in the m-th winding turn.

[0148] In one embodiment, the position of the flags at each winding turn can be adjusted by adjusting the width of the flags (flag bottom length (B), flag top length (U)) and the spacing between flags (D).

[0149] In one embodiment, the electrode assembly (200) may satisfy the following equation 4.

[0150] [Formula 4]

[0151] Bm / Rm=Bm+1 / Rm+1

[0152] In the above equation 4,

[0153] Bm is the length of the base of the flag of the mth winding turn,

[0154] Rm is the radius of curvature of the mth winding turn.

[0155] Referring to FIG. 10, if the number of flags included in the m-th winding turn and the m+1-th winding turn are formed to be the same, and the lower inner angles (θ1, θ2) of the flags (231, 232) included in the m-th winding turn and the m+1-th winding turn have the same size and the above equation 4 is satisfied, the overall shape of the bent flags can have a tapered shape.

[0156] According to one embodiment, the electrode of the electrode assembly (200) is formed by bending a flag formed on a non-conductive portion to form a bend portion, and the bend portion can be electrically connected to the current collector (140).

[0157] According to one embodiment, by adjusting the width of the flags, the spacing (D) between the flags, and the size of the lower inner angles (θ1, θ2) of the flags (231, 232), a flat folded portion without interference between adjacent non-conductive portions can be formed. Accordingly, the weldability and contactability with the current collector (140) can be excellent. As the weldability and contactability between the electrode assembly (200) and the current collector (140) are improved, the internal resistance of the battery cell can be reduced, and the energy density of the battery cell can be improved. In addition, by adjusting the ratio of the flag overlapping area, the movement of the electrolyte can be facilitated when the electrolyte is injected, thereby improving the electrolyte impregnation property.

[0158] Hereinafter, the present invention will be described in more detail through examples according to one embodiment of the present invention, but these examples do not limit the scope of the present invention.

[0159] Manufacturing example

[0160] The minimum spacing (D1m) between flags was calculated under the conditions shown in Table 1 below, and with reference to this, an electrode assembly was manufactured under the conditions shown in Table 2 below. Dm1 in Table 2 is the same value as Dm1 described in Table 1.

[0161] [Table 1]

[0162]

[0163] [Table 2]

[0164]

[0165] [evaluation]

[0166] 1. Weldability Evaluation

[0167] The electrode assembly manufactured above was welded to a current collector, and then the weld strength was measured. The weld strength was measured by welding the electrode assembly to the current collector, pulling the current collector vertically, and measuring the maximum strength at fracture. The results are shown in Table 3 below.

[0168] 2. Electrolyte impregnation

[0169] The electrode assembly welded to the current collector was immersed in a DMC solution to impregnate the electrolyte. The degree of impregnation was determined by disassembling the electrode assembly and measuring the time until the electrode was completely impregnated. Before 12 hours of electrolyte impregnation, the electrode assembly was disassembled every hour, and after 12 hours, it was disassembled every 6 hours to determine the impregnation completion time. The results are shown in Table 3 below.

[0170] [Table 3]

[0171]

[0172] Referring to Table 3 above, it can be confirmed that in the case of an embodiment according to one embodiment of the present disclosure, compared to the comparative example, the contact area between the electrode and the collector plate is secured to the maximum extent, so that the welding strength with the collector plate is excellent, and the gap between the flags is controlled, so that the electrolyte impregnation property is excellent.

[0173] Specifically, in the case of Examples 1 to 4, the welding strength was 30 kgf or more, so the durability of the battery is expected to be excellent. However, in the case of Comparative Examples 1 to 5, the welding strength was less than 30 kgf, so the durability of the battery is expected to be low. In addition, in the case of Examples 1 to 4, the electrolyte was quickly impregnated in 12 hours or less. In Comparative Examples 1 to 3, the gap between the flags was too small, so the electrolyte impregnation time was much longer than 12 hours. Since the electrolyte impregnation must be completed before 12 hours to ensure productivity, it is thought that the productivity of Comparative Examples 1 to 4 is low. In addition, in Comparative Examples 4 and 5, the electrolyte impregnation time was completed quickly, but the welding strength was low, so although the productivity may be excellent, the battery durability is expected to be low. That is, according to one embodiment of the present disclosure, sufficient welding strength can be secured while simultaneously satisfying a short impregnation time.

[0174] Various aspects of the present disclosure are as follows.

[0175] A first aspect: An electrode assembly comprising a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; is wound in a roll shape, wherein the non-conductive portion includes a plurality of flags formed at a predetermined interval from each other, and the plurality of flags are bent in the direction of a central axis along which the electrode is wound to form a bent portion, and when bent, flags disposed in the same winding turn do not overlap each other, and an interval (Dm) between flags disposed in the same winding turn satisfies the following equation 1.

[0176] [Formula 1]

[0177] Dm1 ≤ Dm ≤ 2.5*Dm1

[0178] Also, in the above equation 1,

[0179] , and Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 can be the sizes of the lower interior angles of the flags in the mth winding turn.

[0180] Second aspect: In the first aspect, an electrode assembly can be provided in which the number of flags arranged in the same winding turn increases as one moves from the central axis of the winding roll to the outer circumference.

[0181] In the third aspect, the first aspect or the second aspect, an electrode assembly satisfying the following equation 2 can be provided.

[0182] [Formula 2]

[0183] D m ≥(2πR m -B m ×U nn ) / U nn

[0184] Also, in the above equation 2, D m is the spacing between flags placed in the mth winding turn, and R m is the radius of curvature at the mth winding turn, and B m is the length of the base of the flag of the mth winding turn, and U nn can be the number of flags placed in the mth winding turn.

[0185] Aspect 4: In any one of the first to third aspects, an electrode assembly can be provided in which the number of flags included in the m-th winding turn and the m+1-th winding turn are the same, and the lengths (B) of the bases of the flags included in the m-th winding turn and the m+1-th winding turn are the same.

[0186] Aspect 5: In any one of the aspects 1 to 4, the electrode assembly can provide an electrode assembly that satisfies the following equation 3.

[0187] [Formula 3]

[0188] θ≤90°-(180° / (2πRm / Bm)

[0189] In addition, in the above equation 3, θ is θ1 or θ2, θ1 and θ2 are sizes of the lower inner angle of the flag placed in the m-th winding turn, which may be the same or different, Bm is the length of the base of the flag placed in the m-th winding turn, and Rm may be the radius of curvature of the m-th winding turn.

[0190] Aspect 6: In any one of the first to fifth aspects, an electrode assembly can be provided in which an overlapping area between one flag bending portion arranged in the m-th winding turn and the flag bending portion of the (m+1)-th winding turn is 20 to 95% of the total area of ​​one side of one flag bending portion arranged in the m-th winding turn.

[0191] A seventh aspect: In any one of the first to sixth aspects, a battery cell may be provided, comprising: an electrode including a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; an electrode assembly wound in a roll shape; and a case accommodating the electrode assembly; wherein the non-conductive portion includes a plurality of flags formed at a predetermined interval from each other, and the plurality of flags are bent in the direction of a central axis along which the electrode is wound to form a bent portion, and when bent, flags disposed in the same winding turn do not overlap each other, and a gap (Dm) between flags disposed in the same winding turn satisfies the following equation 1.

[0192] [Formula 1]

[0193] Dm1 ≤ Dm ≤ 2.5*Dm1

[0194] Also, in the above equation 1,

[0195] , and Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 can be the sizes of the lower interior angles of the flags in the mth winding turn.

[0196] Aspect 8: In any one of the first to seventh aspects, the case may provide a battery cell including a case body including an opening for accommodating the electrode assembly and a cap plate covering the case body.

[0197] Aspect 9: In any one of the first to eighth aspects, a battery cell including a current collector electrically connected to the flag bending portion can be provided.

[0198] Aspect 10: In any one of the first to ninth aspects, a battery cell may be provided in which the flag bending portion and the current collector plate are joined by welding.

[0199] Aspect 11: In any one of the first to tenth aspects, the electrode assembly can provide a battery cell in which the number of flags arranged in the same winding turn increases as the number of flags increases from the central axis of the winding roll toward the outer circumference.

[0200] The present disclosure may be implemented in various forms, and the scope of the invention is not limited to the embodiments described above. Therefore, if a modified embodiment includes elements of the claims of the present disclosure, it should be considered within the scope of the present disclosure.

Claims

1. An electrode including a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; are wound in a roll shape, An electrode assembly in which the above-mentioned flag portion includes a plurality of flags formed at a predetermined interval from each other, the plurality of flags are bent in the direction of the central axis along which the electrode is wound to form a bent portion, and the flags arranged in the same winding turn do not overlap each other when bent, and the interval (Dm) between the flags arranged in the same winding turn satisfies the following equation 1. [Formula 1] Dm1 ≤ Dm ≤ 2.5*Dm1 In the above equation 1, And, The above Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 are the sizes of the lower interior angles of the flags in the mth winding turn.

2. In paragraph 1, An electrode assembly in which the number of flags arranged in the same winding turn increases as one moves from the central axis of the winding roll to the outer circumference.

3. In paragraph 1, An electrode assembly satisfying the following equation 2; [Formula 2] D m ≥(2πR m -B m ×U nn ) / U nn In the above equation 2, D m is the spacing between flags placed in the mth winding turn, and R m is the radius of curvature at the mth winding turn, and B m is the length of the base of the flag of the mth winding turn, and U nn is the number of flags placed in the mth winding turn.

4. In paragraph 1, An electrode assembly in which the number of flags included in the m-th winding turn and the m+1-th winding turn are the same, and the lengths (B) of the bases of the flags included in the m-th winding turn and the m+1-th winding turn are the same.

5. In paragraph 1, The above electrode assembly is an electrode assembly satisfying the following equation 3; [Formula 3] θ≤90°-(180° / (2πRm / Bm) In the above equation 3, θ is θ1 or θ2, and θ1 and θ2 are the sizes of the lower interior angles of the flags arranged in the mth winding turn, which may be equal or different, Bm is the length of the base of the flag placed in the mth winding turn, Rm is the radius of curvature of the mth winding turn.

6. In paragraph 1, An electrode assembly wherein an overlapping area between one flag bending part arranged in the mth winding turn and the flag bending part of the (m+1)th winding turn is 20 to 95% of the total area of ​​one side of one flag bending part arranged in the mth winding turn.

7. An electrode assembly including a current collector, an active material layer formed on the current collector, and a non-conductive portion on which the active material layer is not formed; and a separator disposed on the electrode; and the electrode assembly is wound in a roll shape; and A case for accommodating the electrode assembly; A battery cell in which the above-mentioned non-conductive portion includes a plurality of flags formed at a predetermined interval from each other, the plurality of flags are bent in the direction of the central axis along which the electrode is wound to form a bent portion, and the flags arranged in the same winding turn do not overlap each other when bent, and the interval (Dm) between the flags arranged in the same winding turn satisfies the following equation 1. [Formula 1] Dm1 ≤ Dm ≤ 2.5*Dm1 In the above equation 1, And, The above Dm is the spacing between flags in the mth winding turn, Rm is the radius of curvature in the mth winding turn, H is the height of the flag in the mth winding turn, B is the length of the base of the flag in the mth winding turn, and θ1 and θ2 are the sizes of the lower interior angles of the flags in the mth winding turn.

8. In paragraph 7, A battery cell including a case body including an opening for accommodating the electrode assembly and a cap plate covering the case body.

9. In paragraph 7, A battery cell comprising a current collector plate electrically connected to the above flag bending portion.

10. In paragraph 9, A battery cell in which the above flag bending portion and the current collecting plate are joined by welding.

11. In paragraph 7, The above electrode assembly is a battery cell in which the number of flags arranged in the same winding turn increases as one goes from the central axis of the winding roll to the outer circumference.

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