Electrode assembly, cylindrical battery, and battery pack and vehicle comprising same

Abstract

The invention provides an electrode assembly, a cylindrical battery, a battery pack and a vehicle. The electrode assembly includes a first electrode, a second electrode, and a separator disposed therebetween, which is wound about one axis to define a core and an outer periphery. At least one of the first electrode and the second electrode includes an uncoated portion extending along a long side end thereof in the winding direction. The uncoated portion includes a plurality of segments that are separated by slits formed in the winding direction and that are independently bendable. The plurality of segments are bent toward the core to form a curved surface area at one end of the electrode assembly. At least a portion of the plurality of segments includes a folded end.

Description

Technical Field

[0001] The present application relates to an electrode assembly, a cylindrical battery, a battery pack including the same, and a vehicle.

[0002] The present application claims the priority of Korean Patent Application No. 10-2023-0105883, filed on August 11, 2023, and Korean Patent Application No. 10-2024-0107867, filed on August 12, 2024, in the Republic of Korea, the disclosures of which are incorporated herein by reference. Background Art

[0003] Secondary batteries that can be easily applied to various product groups and have electrical characteristics (such as high energy density) are widely used not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by electric drive sources.

[0004] These secondary batteries are attracting attention as new energy sources for improving environmental friendliness and energy efficiency because they have the primary advantage of significantly reducing the use of fossil fuels and the secondary advantage of not generating by-products when using energy.

[0005] Secondary batteries currently widely used in the art include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. The operating voltage of a single secondary battery (i.e., a single cell) is approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries can be connected in series to configure a battery pack. In addition, multiple batteries can be connected in parallel according to the charge / discharge capacity required for the battery pack to form a battery pack. Therefore, various settings can be made for the number of batteries included in the battery pack and the form of electrical connection according to the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, as a type of single secondary battery, cylindrical batteries, prismatic batteries, and pouch batteries are known. In the case of a cylindrical battery, a separator serving as an insulator is disposed between the positive electrode and the negative electrode, and they are wound to form an electrode assembly in the form of a jelly roll, and the electrode assembly is placed in a battery case to configure a battery. In the art, the battery case is called a battery can. In addition, strip-shaped electrode tabs can be connected to the uncoated portions of each positive electrode and negative electrode, and the electrode tabs electrically connect the electrode assembly to the exposed electrode terminals. For reference, the positive electrode terminal is the cover of the sealing body that seals the opening of the battery case, and the negative electrode terminal is the battery case. However, according to a conventional cylindrical battery having such a structure, since the current is concentrated in the strip-shaped electrode tabs connected to the uncoated portion of the positive electrode and / or the uncoated portion of the negative electrode, the current collection effect is poor due to high resistance and large heat generation.

[0007] For small cylindrical batteries with a form factor of 1865 (diameter: 18 mm, height: 65 mm) or a form factor of 2170 (diameter: 21 mm, height: 70 mm), resistance and heat are not major issues. However, when increasing the form factor to apply the cylindrical battery to an electric vehicle, the cylindrical battery may catch fire while generating a large amount of heat around the electrode tabs during rapid charging.

[0008] To solve this problem, a cylindrical battery (so-called tabless cylindrical battery) is provided, in which the uncoated portion of the positive electrode and the uncoated portion of the negative electrode are designed to be located at the top and bottom of the wound core-type electrode assembly, respectively, and the current collector is welded to the uncoated portion to improve the current collection efficiency.

[0009] Figures 1 to 3 It is a diagram showing the manufacturing process of a tabless cylindrical battery. Figure 1 It shows the structure of the electrode, Figure 2 It shows the electrode winding process, and Figure 3 It shows the process of welding the current collector to the curved surface area of the uncoated portion.

[0010] Referring to Figures 1 to 3 , the positive electrode 10 and the negative electrode 11 have a structure in which a sheet-shaped current collector 20 is coated with an active material layer 21, and an uncoated portion 22 is included in the long side in the winding direction X. The long side refers to the side with a relatively longer length in the direction parallel to the X-axis direction.

[0011] The electrode assembly A is manufactured by: as Figure 2 shown, the positive electrode 10 and the negative electrode 11 are sequentially laminated together with two layers of separator 12, and then wound in one direction X along one axis of the core 33. The lamination order of the positive electrode 10 and the negative electrode 11 can be opposite to that shown in the figure. The arrangement directions of the uncoated portions of the positive electrode 10 and the negative electrode 11 are opposite.

[0012] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are bent toward the core. Thereafter, the current collectors 30, 31 are welded and connected to the uncoated portions 10a, 11a, respectively.

[0013] The electrode tabs are not separately connected to the uncoated portion 10a of the positive electrode and the uncoated portion 11a of the negative electrode. The current collectors 30, 31 are connected to the external electrode terminals, and a current path is formed with a relatively large cross-sectional area in the direction of the winding axis of the electrode assembly A (see the arrow), which has the advantage of reducing the battery resistance. This is because the resistance is inversely proportional to the cross-sectional area of the path through which the current flows.

[0014] At the same time, as Figure 3As shown, the bent portions of the uncoated portions 10a and 11a welded with the current collectors 30 and 31 are stacked in multiple layers. Therefore, the bent surface area formed when bending the uncoated portions 10a and 11a has almost no gaps through which the electrolyte can pass in the winding axis direction. This is because most of the gaps between the winding corners that exist immediately after winding disappear during the process of bending the uncoated portions 10a and 11a. Therefore, a conventional electrode assembly manufactured as an earless structure has the disadvantage of slow electrolyte impregnation speed. This is because there are not enough gaps in the bent surface area for the electrolyte to migrate into the interior of the electrode assembly. Summary of the Invention

[0015] Technical Problem

[0016] The present invention aims to solve the problems of the related art. Therefore, the present invention aims to provide an electrode assembly having an earless structure, in which the uncoated portion of the electrode has an improved structure, so that gaps are sufficiently formed in the bent surface area of the uncoated portion, and the electrolyte can pass through the gaps and be impregnated into the electrode assembly.

[0017] The present invention also aims to provide a battery including the electrode assembly having an improved structure, a battery pack including the battery, and a vehicle including the battery pack.

[0018] The technical objectives to be solved by the present invention are not limited to the above, and those skilled in the art will clearly understand other objectives not mentioned herein from the following description of the invention.

[0019] Technical Solution

[0020] In one aspect of the present invention, there is provided an electrode assembly, in which a first electrode, a second electrode, and a separator disposed therebetween are wound around an axis to define a core portion and an outer periphery. Wherein, at least one of the first electrode and the second electrode includes an uncoated portion extending along its long side end in the winding direction. Wherein, the uncoated portion includes a plurality of sections separated by slits formed along the winding direction and capable of being independently bent. Wherein, the plurality of sections are bent toward the core portion to form a bent surface area at one end of the electrode assembly. And wherein, at least a part of the plurality of sections includes folded ends.

[0021] In the present invention, the section including the folded end is defined as an end-folded section, and the number of uncoated portions intersecting with an imaginary straight line passing through the center of the folded end is defined as the fold number of the folded end.

[0022] The bent surface area may include a plurality of end-folded sections.

[0023] The fold number of the folded end may be 2 or more, and gaps may be formed between adjacent sections in the radial direction of the electrode assembly.

[0024] The gap may have a separation distance corresponding to the thickness of the folded end between adjacent sections in the radial direction of the electrode assembly.

[0025] The plurality of end-folded sections may be arranged in a regular or irregular pattern on the curved surface region in the radial direction or circumferential direction of the electrode assembly.

[0026] The curved surface region may include a radial region in which the number of the end-folded sections arranged in the circumferential direction increases stepwise or gradually from the core to the outer periphery.

[0027] The curved surface region may include a radial region in which the number of folds of the folded end increases stepwise or gradually from the core to the outer periphery.

[0028] The curved surface region may include a radial region in which the number of folds of the folded end remains consistent from the core to the outer periphery.

[0029] The height of the plurality of end-folded sections may increase stepwise from the core to the outer periphery of the electrode assembly. In this case, the curved surface region may include a radial region in which the number of folds of the folded end increases as the height of the end-folded section increases.

[0030] The curved surface region may include a radial region in which the width of the uncoated portion forming the folded end in the direction of the one axis increases stepwise or gradually from the core to the outer periphery of the electrode assembly.

[0031] In the present invention, at any point in the curved surface region, the number of uncoated portions intersecting a hypothetical line passing through the curved surface region and parallel to the direction of the one axis is defined as the number of stacked layers of the uncoated portion at the corresponding point.

[0032] The curved surface region may include a region where the number of stacked layers increases and a region where the number of stacked layers is consistent.

[0033] The region where the number of stacked layers increases may be positioned closer to the outer periphery of the electrode assembly, and the region where the number of stacked layers is consistent may be located between the region where the number of stacked layers increases and the core of the electrode assembly.

[0034] The number of end-folded sections included in the region where the number of stacked layers increases may be greater than the number of end-folded sections included in the region where the number of stacked layers is consistent.

[0035] The number of folds of the folded end included in the region where the number of stacked layers is consistent may be greater than the number of folds of the folded end included in the region where the number of stacked layers increases.

[0036] The folding end portion may have a structure folded into a core shape, a structure folded into a zigzag shape, or a randomly folded structure.

[0037] In another aspect of the present invention, a cylindrical battery is provided, which includes: an electrode assembly, wherein a first electrode, a second electrode, and a separator disposed therebetween are wound around an axis to define a core portion and an outer periphery, and the electrode assembly includes at least one of the above features; a battery case having an open end and a closed end and configured to accommodate the electrode assembly through the open end, the battery case being electrically connected to the second electrode of the electrode assembly; a sealing body configured to seal the open end of the battery case; and a terminal electrically connected to the first electrode of the electrode assembly and having a surface exposed outside the battery case.

[0038] The curved surface region may be formed by bending a plurality of segments included in the uncoated portion of the first electrode.

[0039] The cylindrical battery may further include a first current collector plate that electrically connects the curved surface region formed by the uncoated portion of the first electrode to the terminal.

[0040] The terminal may be installed in a through hole formed in the closed end of the battery case to be insulated from the battery case. A gasket may be disposed between the terminal and the through hole.

[0041] The terminal may include a terminal exposed portion exposed through the outer surface of the closed end, and a terminal insertion portion extending from the terminal exposed portion and inserted into the battery case through the through hole.

[0042] The lower edge of the terminal insertion portion may be riveted to the inner surface of the closed end.

[0043] The sealing body may include a cover plate that seals the open end of the battery case.

[0044] A gasket may be disposed between the edge of the cover plate and the open end of the battery case.

[0045] The terminal may be the cover plate.

[0046] The curved surface region may be formed by bending the plurality of segments included in the uncoated portion of the second electrode.

[0047] The cylindrical battery may further include a second current collector plate that electrically connects the curved surface region formed by the uncoated portion of the second electrode to the side wall of the battery case.

[0048] The battery housing may include a flange portion formed by pressing the outer periphery near the open end inward.

[0049] The edge of the second current collector plate may be disposed between the gasket and the side wall of the battery housing.

[0050] The edge of the second current collector plate may contact the side wall (e.g., the flange portion) of the battery housing.

[0051] If the side wall of the battery housing does not include a flange portion, the side wall may extend along a straight line between the closed end and the open end. In this case, the edge of the cover plate may be welded to the open end.

[0052] At least a part of the second current collector plate may be welded to the cover plate.

[0053] The second current collector plate may be electrically connected to the cover plate.

[0054] At least the inner region of the edge portion of the cover plate may be welded to the curved surface region formed by the uncoated portion of the second electrode facing the cover plate. In this case, the cover plate may substitute for the function of the second current collector plate.

[0055] In yet another aspect of the present invention, a battery pack is provided, which includes a plurality of the above-described cylindrical batteries.

[0056] In yet another aspect of the present invention, a vehicle is provided, which includes the battery pack.

[0057] Advantageous Effects

[0058] According to the present invention, by improving the end structure of the section, a gap serving as an electrolyte impregnation path can be sufficiently formed in the curved surface region formed by bending the section in the radial direction and / or the circumferential direction, thereby shortening the electrolyte impregnation time.

[0059] According to another aspect of the present invention, a cylindrical battery, a battery pack, and a vehicle including the cylindrical battery can be provided. The cylindrical battery includes an electrode assembly having improved electrolyte impregnation property, low internal resistance, and improved welding strength between the current collector and the uncoated portion.

[0060] In addition, the present invention may have some other effects, and these effects will be described in each embodiment, or any description of effects that can be easily inferred by those skilled in the art will be omitted. Brief Description of the Drawings

[0061] The drawings illustrate preferred embodiments of the present invention and, together with the following disclosure, serve to provide a further understanding of the technical features of the present invention. Therefore, the present invention is not construed as being limited to the drawings.

[0062] Figure 1 is a plan view showing an electrode structure for manufacturing a conventional tabless cylindrical battery.

[0063] Figure 2 is a view showing an electrode winding process of a conventional tabless cylindrical battery.

[0064] Figure 3 is a view showing a process of welding a current collector to a curved surface area of an uncoated portion in a conventional tabless cylindrical battery.

[0065] Figure 4 is a plan view showing an electrode structure according to an embodiment of the present invention.

[0066] Figure 5 is a plan view exemplarily showing an electrode structure according to an embodiment of the present invention including a plurality of end folding sections.

[0067] Figure 6 is a view showing that the folded end is along Figure 5 a cross-sectional structure of the A-A' line.

[0068] Figure 7 is a view showing that the folded end is along Figure 5 another cross-sectional structure of the A-A' line.

[0069] Figure 8 is a view showing that the folded end is along Figure 5 yet another cross-sectional structure of the A-A' line.

[0070] Figure 9 is a view showing that the folded end is along Figure 5 yet another cross-sectional structure of the A-A' line.

[0071] Figure 10a is a perspective view showing an upper structure of an electrode assembly having a curved surface area according to an embodiment of the present invention.

[0072] Figure 10b is a plan view schematically showing the position of a folded end on a curved surface area according to an embodiment of the present invention with a dashed frame.

[0073] Figure 10c is a cross-sectional view showing a part of a curved surface area according to an embodiment of the present invention taken along the winding axis direction of the electrode assembly.

[0074] Figure 11 is a cross-sectional view showing a wound-core type electrode assembly in which an electrode according to an embodiment of the present invention is applied to a first electrode (positive electrode) and a second electrode (negative electrode) taken along the winding axis direction Y.

[0075] Figure 12 is a cross-sectional view taken along the winding axis direction Y of a cylindrical battery showing one embodiment of the present invention.

[0076] Figure 13 is a cross-sectional view taken along the winding axis direction Y of a cylindrical battery showing another embodiment of the present invention.

[0077] Figure 14 is a diagram schematically showing a battery pack of one embodiment of the present invention.

[0078] Figure 15 is a diagram schematically showing a vehicle including a battery pack of one embodiment of the present invention. Detailed Embodiments

[0079] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to the conventional meanings or dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present invention according to the principle that allows the inventor to appropriately define the terms for the best explanation.

[0080] Therefore, the description given herein is only a preferred example for illustrative purposes and is not intended to limit the scope of the present invention. Thus, it should be understood that other equivalents and modifications can be made thereto without departing from the scope of the present invention.

[0081] In addition, for the purpose of facilitating the understanding of the present invention, the drawings are not drawn to scale and may exaggerate the dimensions of some components. Furthermore, the same components in different embodiments may be designated with the same reference numerals.

[0082] Stating that two comparison objects are "the same" means that they are "substantially the same". Therefore, the term "substantially the same" may include deviations considered to be low in the art, such as deviations less than 10%. In addition, the parameters being consistent within a region may mean that the parameters are consistent in terms of the average value in the corresponding region.

[0083] Although terms such as first and second are used to describe different elements, these elements are not limited by the terms. These terms are used to distinguish one element from another, and unless otherwise stated, the first element may be the second element.

[0084] Throughout the specification, unless otherwise stated, each element may be singular or plural.

[0085] When an element is "above (or below)" or "on (under)" another element, the element can be located on the upper surface (or lower surface) of the other element, and there can be intermediate elements between the element and the other element on (or under) the element.

[0086] In addition, when an element is referred to as being "connected", "joined", or "coupled" to another element, the element can be directly connected or joined to the other element, but it should be understood that there can be intermediate elements between the elements, or the elements can be "connected", "joined", or "coupled" to each other through another element.

[0087] Throughout the specification, "A and / or B" means either A or B or both A and B, unless otherwise explicitly stated, and "C to D" means above C and below D, unless otherwise explicitly stated.

[0088] For ease of description, herein, the direction extending along the length direction of the winding axis of the wound electrode assembly in a roll shape is referred to as the axial direction Y. In addition, herein, the direction around the winding axis is referred to as the circumferential or outer peripheral direction X. In addition, the direction approaching or departing from the winding axis is referred to as the radial direction. Among them, in particular, the direction approaching the winding axis is referred to as the centripetal direction, and the direction departing from the winding axis is referred to as the centrifugal direction.

[0089] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly can be a wound core type electrode assembly having a structure in which a sheet-shaped first electrode and a second electrode are wound in one direction with a separator disposed therebetween.

[0090] At least one of the first electrode and the second electrode includes an uncoated portion at a long side end in the winding direction that is not coated with an active material. At least a part of the uncoated portion itself serves as an electrode tab. The uncoated portion includes a core-side uncoated portion adjacent to the core portion of the electrode assembly, an outer peripheral-side uncoated portion adjacent to the outer periphery of the electrode assembly, and an intermediate uncoated portion sandwiched between the core-side uncoated portion and the outer peripheral-side uncoated portion.

[0091] Preferably, the height of at least one of the core-side uncoated portion and the outer peripheral-side uncoated portion is relatively lower than that of the intermediate uncoated portion.

[0092] Figure 4 is a plan view showing the structure of an electrode 60 according to an embodiment of the present invention.

[0093] Refer to Figure 4, the electrode 60 of the present embodiment includes a current collector 41 made of a metal foil and an active material layer 42. The metal foil may be a conductive metal such as aluminum or copper, and is appropriately selected according to the polarity of the electrode 60. The active material layer 42 is formed on at least one surface of the current collector 41. The active material layer 42 is formed along the winding direction X. The long side end of the electrode 60 in the winding direction X includes an uncoated portion 43. The uncoated portion 43 is a partial area of the current collector 41 that is not coated with the active material.

[0094] In the electrode 60, the width of the active material portion in the short side direction of the current collector 41 may be 50 mm to 120 mm, and the width of the active material portion in the long side direction of the current collector 41 may be 3 m to 5 m.

[0095] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 is formed such that at least a part of it overlaps with the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44, together with the separator disposed therebetween, prevents a short circuit between two electrodes having different polarities and facing each other. The insulating coating layer 44 may cover a boundary with a width of 0.3 mm to 5 mm between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 may include a polymer resin and inorganic fillers such as SiO2 and Al2O3. Since the portion of the current collector 41 covered with the insulating coating layer 44 is not an area covered with the active material, it can be regarded as an uncoated portion.

[0096] The uncoated portion 43 includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion B3 adjacent to the outer periphery of the electrode assembly, and an intermediate uncoated portion B2 sandwiched between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0097] When the electrode 60 is wound into a core-type electrode assembly, the core-side uncoated portion B1, the outer-periphery-side uncoated portion B3, and the intermediate uncoated portion B3 can be respectively defined as the uncoated portion in the area adjacent to the core, the uncoated portion in the area adjacent to the outer periphery, and the uncoated portion in the remaining area other than the above areas.

[0098] Hereinafter, the core-side uncoated portion B1, the outer-periphery-side uncoated portion B3, and the intermediate uncoated portion B2 are respectively referred to as the first portion, the second portion, and the third portion.

[0099] In one example, the first portion B1 may be the uncoated portion of the electrode area including the innermost winding turn, and the second portion B3 may be the uncoated portion of the electrode area including the outermost winding turn. The winding turns can be counted based on the core-side end of the electrode assembly.

[0100] In another example, the boundary between B1 and B2 can be appropriately defined as the point where the height (or varying pattern) of the uncoated portion substantially changes when going from the core of the electrode assembly to the outer periphery, or as the point at a predetermined percentage (e.g., 5% point, 10% point, 15% point, etc.) of the radius of the electrode assembly.

[0101] The boundary between B2 and B3 can be defined as the point where the height (or varying pattern) of the uncoated portion substantially changes when going from the outer periphery of the electrode assembly to the core, or as the point at a predetermined percentage (e.g., 85% point, 90% point, 95% point, etc.) of the radius of the electrode assembly. When the boundaries of B1 / B2 and B2 / B3 are specified, the third part B2 can be automatically specified.

[0102] If only the boundary of B1 / B2 is specified, the boundary of B2 / B3 can be appropriately selected at a point near the outer periphery of the electrode assembly. In one example, the second part can be defined as the uncoated portion of the electrode area constituting the outermost winding turn. Conversely, when only the boundary of B2 / B3 is specified, the boundary of B1 / B2 can be appropriately selected at a point near the core of the electrode assembly. In one example, the first part B1 can be defined as the uncoated portion of the electrode area constituting the innermost winding turn.

[0103] It is not excluded that another structure is provided between the first part B1 and the third part B2. Additionally, it is not excluded that another structure is provided between the third part B2 and the second part B3.

[0104] In the electrode 60, the heights of the first part B1 and the second part B3 are 0 or more, but are relatively smaller than the third part B2. Additionally, the heights of the first part B1 and the second part B3 can be the same or different. In the winding direction, the third part B2 is longer than the first part B1 and the second part B3.

[0105] The width (d B1 ) of the first part B1 is designed by applying the condition that it does not cover the core of the electrode assembly when bending the uncoated portion of the third part B2 towards the core. The core refers to the cavity existing at the winding center of the electrode assembly. The width (d B1 ) of the first part B1 can increase proportionally to the bending length of the uncoated portion closest to the core. The width (d B1 ) of the first part B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly and the bending length of the uncoated portion closest to the core.

[0106] The uncoated portion of the third part B2 can include a plurality of sections 61 separated by the cut grooves 63 formed along the winding direction X and capable of being bent independently.

[0107] The height of the multiple segments 61 can increase stepwise from the core to the outer periphery. Alternatively, the multiple segments 61 can have the same height from the core to the outer periphery.

[0108] The multiple segments 61 have a geometry with a width decreasing from the bottom to the top. The geometric shape can be an irregular quadrilateral. The shape of the geometric figure can be modified into various forms, such as a rectangle, a parallelogram, etc.

[0109] The segments 61 can be formed by laser scribing. The cut grooves 63 are formed between the segments 61 along the winding direction X. When the shape of the segment 61 is a rectangle or an irregular quadrilateral, the cut grooves 63 can have a linear shape. The multiple segments 61 can be formed by known metal foil cutting processes (such as ultrasonic cutting or punching).

[0110] At least a part of the multiple segments 61 can include folded ends 61a.

[0111] Figure 5 is a plan view showing the structure of an electrode 60 including multiple end-folded segments 61' which exemplarily shows an embodiment of the present invention.

[0112] Figures 6 to 9 shows the folded ends along Figure 5 the cross-sectional structures at various positions along the A-A' line.

[0113] Referring to Figures 4 to 9 , the folded ends 61a are formed only in a part of the multiple segments 61. The segment 61 including the folded ends 61a is defined as an end-folded segment 61'. The folded ends 61a are formed by folding the ends of the end-folded segment 61' at least once. The part of the end-folded segment 61' where the folded ends 61a are formed is the area above the dotted line (see Figure 4 ). In Figure 4 , the folded ends 61a are in the state before folding.

[0114] In the end-folded segment 61', the widths of the parts where the folded ends 61a are formed can be the same or different. Here, the width is the width in the winding axis direction Y.

[0115] In the end-folded segment 61', the widths of the parts where the folded ends 61a are formed can increase or decrease stepwise or gradually from the core of the electrode assembly to the outer periphery.

[0116] In the end-folded segment 61', the widths of the parts where the folded ends 61a are formed can vary irregularly from the core of the electrode assembly to the outer periphery.

[0117] The folded ends 61a can have a shape as shown in Figure 6The winding core structure wound into a straight line as shown. The folded end 61a can be arranged to face the core part of the electrode assembly. Different from the illustrated example, the folded end 61a can be arranged to face the outer periphery of the electrode assembly.

[0118] In another example, the folded shape of the folded end 61a can have a winding core structure wound into an arc shape as Figure 7 shown. The folded end 61a can be arranged to face the core part of the electrode assembly. Different from the illustrated example, the folded end 61a can be arranged to face the outer periphery of the electrode assembly.

[0119] In yet another example, the folded shape of the folded end 61a can have a structure folded into a zigzag shape as Figure 8 shown. The folded end 61a can be arranged to face the core part of the electrode assembly. Different from the illustrated example, the folded end 61a can be arranged to face the outer periphery of the electrode assembly.

[0120] In yet another example, the folded shape of the folded end 61a can have a random folding structure as Figure 9 shown. In this case, a part of the folded end 61a can be arranged to face the core part of the electrode assembly, and another part of the folded end 61a can be arranged to face the outer periphery of the electrode assembly.

[0121] The number of folds of the folded end 61a can be defined.

[0122] As Figures 6 to 9 shown, the number of folds can be the number of uncoated portions that intersect with the imaginary straight line L passing through the center 62 of the folded end 61a. The imaginary straight line L can be substantially perpendicular to the portion of the uncoated portion other than the folded end 61a. The center 62 of the folded end 61a can be the centroid of the projected portion when the folded end 61a is projected onto a predetermined plane. The plane on which the folded end 61a is projected can be the plane where the end folding section 61' exists. Figures 6 to 9 The number of folds of the folded end 61a included in the end folding section 61' shown in is 4. If the structure of the folded end 61a changes, the number of folds can also change.

[0123] When the electrode 60 is included as an electrode of the electrode assembly having a winding core structure, the plurality of sections 61 and the plurality of end folding sections 61' can extend along the winding axis direction Y of the electrode assembly and protrude to the outside of the separator.

[0124] A plurality of sections 61 and a plurality of end-folded sections 61' can be bent in the radial direction of the electrode assembly (e.g., toward the core) to form a curved surface area at one end of the electrode assembly. The bending point can be near the lower end of the slotted groove 63. The bending point can be spaced upward at a distance of 1 mm or less based on the lower end of the slotted groove 63. The curved surface area is approximately perpendicular to the winding axis direction Y.

[0125] Figure 10a FIG. 4 is a perspective view showing an upper structure of an electrode assembly JR having a curved surface area F according to an embodiment of the present invention. Figure 10b FIG. 6 is a plan view schematically showing the position of a folded end 61a on the curved surface area F according to an embodiment of the present invention in a dashed-line frame. In Figure 10b FIG. 6, the structure in which the sections 61 and the end-folded sections 61' overlap in the radial direction is not shown. Figure 10c FIG. 10 is a cross-sectional view taken along the winding axis direction Y of a part of the curved surface area F of the electrode assembly JR.

[0126] Referring to Figure 10a 、 10b FIGS. 17 and 10c, the number of folds of the folded end 61a included in the end-folded section 61' is 2 or more, and a gap G can be formed between the sections 61 adjacent in the radial direction of the electrode assembly JR. The gap G can provide a path for the electrolyte E to be impregnated into the interior of the electrode assembly JR. Since a plurality of gaps G are formed by the plurality of end-folded sections 61' in the curved surface area F, the impregnation speed of the electrolyte can be increased. As a result, the electrolyte injection time can be shortened.

[0127] The gap G can have a separation distance corresponding to the thickness of the folded end 61a between the sections 61 adjacent in the radial direction of the electrode assembly JR. The thickness of the folded end 61a can be defined as the maximum value of the thicknesses measured at a plurality of points of the folded end 61a. As the number of folds of the folded end 61a increases, the separation distance of the gap G increases, and the impregnation speed of the electrolyte can be improved accordingly.

[0128] Referring to Figure 10b FIG. 25, the plurality of end-folded sections 61' can be arranged in a regular or irregular pattern on the curved surface area F in the radial direction or the circumferential direction of the electrode assembly JR.

[0129] In another aspect, the curved surface area F can include a radial area in which the number of end-folded sections 61' arranged in the circumferential direction increases stepwise or gradually from the core C to the outer periphery of the electrode assembly JR.

[0130] In yet another aspect, the curved surface region F may include a radial region in which the number of folds of the folded end 61a increases stepwise or gradually from the core C of the electrode assembly JR toward the outer periphery. That is, in this radial region, the number of folds of the folded end 61a positioned closer to the core C may be smaller than the number of folds of the folded end 61a positioned at the outer periphery.

[0131] In yet another aspect, the curved surface region F may include a radial region in which the number of folds of the folded end 61a remains consistent from the core C of the electrode assembly JR to the outer periphery. That is, in this radial region, the number of folds of the folded end 61a may be the same.

[0132] In yet another aspect, the height of the end folding section 61' may increase gradually from the core C of the electrode assembly JR toward the outer periphery (see Figure 4 ). In this case, the curved surface region F may include a radial region in which the number of folds of the folded end 61a increases as the height of the end folding section 61' increases. That is, in this radial region, the number of folds of the folded end 61a included in the end folding section 61' with a relatively low height may be smaller than the number of folds of the folded end 61a included in the end folding section 61' with a relatively high height.

[0133] In yet another aspect, the curved surface region F may include a radial region in which the width of the uncoated portion in the winding axis direction Y forming the folded end 61a increases stepwise or gradually from the core C of the electrode assembly JR to the outer periphery.

[0134] According to the above-described embodiments, by relatively increasing the number of end folding sections 61' and / or the number of folds of the folded end 61a arranged in the radial region of the curved surface region F where the electrolyte impregnation rate is low, the electrolyte impregnation rate can be improved.

[0135] Referring to Figure 10c , when a hypothetical straight line (L k ) parallel to the winding axis direction Y is drawn at an arbitrary point (r k ) in the curved surface region F, the number of uncoated portions intersecting the hypothetical straight line (L k ) can be defined as the number of stacked layers of the uncoated portion at the corresponding point. When the hypothetical straight line (L k ) intersects the folded end 61a, the number of stacked layers of the uncoated portion only increases by 1. Figure 6 The number of stacked layers of the uncoated portion at the point (r k ) shown is 6.

[0136] In the curved surface region F, the number of layers of the uncoated portion gradually increases from the outer periphery toward the core portion, and when it reaches a predetermined value, a radial region where the number of layers of the uncoated portion remains consistent appears. The layer number consistent region (S2) is the radial region of the electrode assembly JR where the number of layers of the uncoated portion is substantially the same. "Substantially the same" includes cases where the deviation is less than 10%.

[0137] The curved surface F may include a layer number increasing region (S1) and a layer number consistent region (S2). The layer number increasing region (S1) is located closer to the outer periphery of the electrode assembly JR. The layer number consistent region (S2) is located between the layer number increasing region (S1) and the core portion C of the electrode assembly JR. The length of the layer number consistent region (S2) is greater than the length of the layer number increasing region (S1).

[0138] In Figure 10c the example, in the layer number increasing region (S1), the number of layers of the uncoated portion increases from 1 to 13. In the layer number consistent region (S2), the number of layers of the uncoated portion remains 13. When the lengths of the section 61 and the end folding section 61' increase, the number of layers of the uncoated portion in the layer number consistent region (S2) can increase to more than 13.

[0139] Since the number of layers of the uncoated portion in the layer number consistent region (S2) is greater than that in the layer number increasing region (S1), the electrolyte impregnation speed is slow. Therefore, the number of end folding sections 61' included in the layer number consistent region (S2) can be greater than the number of end folding sections included in the layer number increasing region (S1). Alternatively, the number of folds of the folded end 61a included in the layer number consistent region (S2) can be greater than the number of folds of the folded end 61a included in the layer number increasing region (S1). In this case, the electrolyte impregnation speed of the layer number consistent region (S2) with a slow electrolyte impregnation speed can be improved.

[0140] Referring again to Figure 4 and Figure 5 , in order to prevent damage to the active material layer 42 and / or the insulating coating layer 44 during the bending of the uncoated portion 43, it is preferable to provide a predetermined gap between the bottom of the cut groove between the sections 61 and the active material 42. This is because when the uncoated portion 43 is bent, stress is concentrated near the bottom of the cut groove 63. The gap can vary in the winding direction of the electrode 60. The gap is 0.2 mm to 4 mm, preferably 1.5 mm to 2.5 mm. If the gap is adjusted within the corresponding numerical range, damage to the active material layer 42 and / or the insulating coating layer 44 near the bottom of the cut groove 63 due to the stress generated during the bending of the uncoated portion 43 can be prevented. The gap can prevent damage to the active material layer 42 and / or the insulating coating layer 44 due to the tolerance during the cutting or incising of the section 61.

[0141] The lower end of the grooving 63 and the insulating coating layer 44 can be spaced 0.5 mm to 2.0 mm apart. When winding the electrode 60, the end of the insulating coating layer 44 in the winding axis Y direction can be located within the range of -2 mm to 2 mm along the winding axis direction based on the end of the separator. Together with the separator disposed therebetween, the insulating coating layer 44 can prevent a short circuit between two electrodes having different polarities and facing each other, and can support the bending point when bending the section 61. To improve the short-circuit protection effect between the two electrodes, the insulating coating layer 44 can be exposed outside the separator. In addition, to further maximize the short-circuit protection effect between the two electrodes, the width of the insulating coating layer 44 can be increased such that the end of the insulating coating layer 44 in the winding axis Y direction is located above the lower end of the grooving 63. In one embodiment, the end of the insulating coating layer 44 in the winding axis direction can be located within the range of -2 mm to 2 mm based on the lower end of the grooving 63. The thickness of the insulating coating layer 44 can be less than the thickness of the active material layer 42. In this case, a gap can exist between the insulating coating layer 44 and the separator.

[0142] A plurality of sections 61 can form a plurality of section groups from the core to the outer periphery. At least one of the width, height, and separation distance of the sections belonging to the same section group can be substantially the same. Preferably, the width, height, and separation distance of the sections belonging to the same section group can be substantially the same.

[0143] The width of the section 61 roughly corresponds to the width of the lower end. The width of the section 61 can be 1 mm to 11 mm. The width of the section 61 can increase stepwise or gradually as the radius r of the winding turns increases.

[0144] The height of the section 61 approximately corresponds to the shortest distance between the upper end and the lower end. The height of the section 61 can be 2 mm to 10 mm. The height of the section 61 can increase stepwise or gradually in the radial direction of the electrode assembly.

[0145] The separation distance (P) of the section 61 corresponds to the distance between two points where a straight line passing through the lower end of the grooving in the winding direction intersects two straight lines formed by extending the side edges of the section 61 on both sides of the grooving. The separation distance (P) of the section 61 can be 0.05 mm to 1 mm.

[0146] When the section 61 is approximately an irregular quadrilateral, the lower inner angle of the irregular quadrilateral can gradually or stepwise increase from the core to the periphery. If the radius of the electrode assembly increases, the radius of curvature increases. If the lower inner angle (θ) of the section 61 increases as the radius of the electrode assembly increases, the stress generated in the radial direction and the circumferential direction when bending the section 61 can be alleviated. In addition, if the lower inner angle (θ) increases, when bending the section 61, the area and the number of overlapping layers overlapping with the section 61 on the inner side also increase. Therefore, the welding strength can be ensured uniformly in the radial direction and the circumferential direction, and the bent surface area can be formed smoothly.

[0147] The width (d B1 ) of the first part B1 is designed such that when the section 61 of the third part B2 is bent towards the core, the core of the electrode assembly opens more than 50%, more than 60%, more than 70%, more than 80% or more than 90% outward based on its diameter.

[0148] In one embodiment, the width of each section group can be designed for each section group to form the same winding turn of the electrode assembly. Here, the winding turn can be counted based on the end of the first part B1 when the electrode assembly 60 is in the wound state.

[0149] In another variant, the width of each section group can be designed for each section group to form at least one winding turn of the electrode assembly.

[0150] In yet another variant, the width and / or height and / or separation distance of the sections 61 belonging to the same section group can gradually and / or stepwise and / or irregularly increase or decrease within the group or between adjacent groups.

[0151] When the number of section groups is 1, the height of the sections 61 in the third part B2 can be consistent.

[0152] The section structure of the third part B2 can extend to the second part B3. In this case, similar to the third part B2, the second part B3 can also include multiple sections. Preferably, the section structure of the second part B3 can be substantially the same as the outermost section group of the third part B2. In this case, the width, height, and separation distance of the sections included in the second part B3 and the third part B2 can be substantially the same. In a variant example, the width and / or height and / or separation distance of the sections of the second part B3 can be greater than those of the third part B2.

[0153] The structure of the above electrode 60 can be applied to at least one of the first electrode and the second electrode with different polarities included in the electrode assembly having a wound core structure. In addition, when the electrode structure of the above embodiment (variant) is applied to any one of the first electrode and the second electrode, a conventional electrode structure can be applied to the other. In addition, the electrode structures applied to the first electrode and the second electrode may not be the same, but different from each other.

[0154] For example, when the first electrode and the second electrode are the positive electrode and the negative electrode, respectively, any one of the above embodiments (variants) can be applied to the first electrode, and a conventional electrode structure (see Figure 1 ) can be applied to the second electrode.

[0155] As another example, when the first electrode and the second electrode are the positive electrode and the negative electrode, respectively, any one of the above embodiments (variants) can be selectively applied to the first electrode, and another one of the above embodiments (variants) can be selectively applied to the second electrode.

[0156] In the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode can adopt any active material known in the art without limitation.

[0157] In one example, the positive electrode active material may include an alkali metal compound represented by the general formula A[A x M y O 2+z (A includes at least one element among Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≥0, 1≤x + y≤2, -0.1≤z≤2; and the stoichiometric coefficients x, y, z, and M are selected such that the compound remains electrically neutral).

[0158] In another example, the positive electrode active material may be an alkali metal compound xLiM 1 O2-(1 - x)Li2M 2 O3 (wherein, M 1 includes at least one element with an average oxidation state of 3; M 2 includes at least one element with an average oxidation state of 4; and 0≤x≤1).

[0159] In yet another example, the positive electrode active material may be of the general formula Li a M 1 x Fe 1-x M 2y P 1-y M 3 z O 4-z (M 1 comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, and Al; M 2 comprises at least one element selected from Ti, Si, Mn, Co, Fe, Cr, Mo, Ni, Nd, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 comprises a halogen element, optionally including F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; and the stoichiometric coefficients a, x, y, and z are selected such that the compound remains electrically neutral) or a lithium metal phosphate represented by Li3M2(PO4)3 [M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Mg, and Al].

[0160] Preferably, the positive electrode active material may comprise primary particles and / or secondary particles formed by aggregation of primary particles.

[0161] In one example, the negative electrode active material may be a carbon material, a lithium metal or a lithium metal compound, a silicon or a silicon compound, a tin or a tin compound, etc. Metal oxides having a potential less than 2V (such as TiO2 and SnO2) may also be used as the negative electrode active material. As the carbon material, low-crystalline carbon, high-crystalline carbon, etc. may be used.

[0162] The separator may be a porous polymer membrane, for example, a porous polymer membrane made of a polyolefin polymer (such as a homopolymer of ethylene, a homopolymer of propylene, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc.), or a laminate thereof. As another example, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fibers, polyethylene terephthalate, etc.

[0163] At least one surface of the separator may comprise a coating layer of inorganic particles. The separator itself may also be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure combined with a binder, so there is an interstitial volume between adjacent particles.

[0164] Hereinafter, the structure of the electrode assembly according to an embodiment of the present invention will be described in detail.

[0165] Figure 11 is a cross-sectional view taken along the winding axis direction Y of a wound-core type electrode assembly 100 in which an electrode 60 according to an embodiment of the present invention is applied to a first electrode (positive electrode) and a second electrode (negative electrode).

[0166] Refer toFigure 11 , the uncoated portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 100, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and a third portion B2 disposed between the first portion B1 and the second portion B3.

[0167] The height of the uncoated portion of the first portion B1 is lower than the section 61 and the end folding section 61' included in the third portion B2. Therefore, when folding the section 61 and the end folding section 61' included in the third portion B2, the uncoated portion of the first portion B1 will not fold.

[0168] In the third portion B2, the bending length H of the section 61 or the end folding section 61 closest to the core 102 is equal to or less than the radius length (R) of the first portion B1. Therefore, even if the section 61 or the end folding section 61 included in the third portion B2 is folded, the core 102 is open to the outside. If the core 102 is not closed, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. In addition, the process of welding the current collector plate can be easily performed by inserting a welding fixture through the core 102.

[0169] The length of the second portion B3 can be shorter than the length of the first portion B1. The height of the uncoated portion of the second portion B3 is lower than the section 61 or the end folding section 61' included in the third portion B2. Therefore, the following phenomenon can be prevented: due to the process of pressing the circular edge portion of the battery case near the winding turns of the second portion B3, the circular edge portion of the battery case and the upper edge of the electrode assembly 100 come into contact with each other, resulting in an internal short circuit. When folding the section 61 and the end folding section 61' included in the third portion B2, the uncoated portion of the second portion B3 will not fold.

[0170] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a variant, the second uncoated portion 43b can have a conventional electrode structure or the electrode structure in other embodiments (variants).

[0171] A plurality of sections 61 and a plurality of end folding sections 61' included in the third portion B2 of the first uncoated portion 43a and the second uncoated portion 43b can be folded towards the core 102 of the electrode assembly 100 to form a curved surface area F( Figure 10a ). When forming the curved surface area F, the end folding section 61' can be disposed between the sections 61 adjacent in the radial direction of the electrode assembly 100, so as to fold the end 61a to form a gap G( Figure 10c ) to provide an electrolyte impregnation path.

[0172] The electrode assembly of an embodiment of the present invention can be applied to a wound-core cylindrical battery.

[0173] Preferably, the cylindrical battery can be, for example, a cylindrical battery having a form factor ratio (defined as the value obtained by dividing the diameter of the cylindrical battery by its height, i.e., the ratio of the diameter (Φ) to the height H) greater than about 0.4. Here, the form factor represents the value indicating the diameter and height of the cylindrical battery.

[0174] The diameter of the cylindrical battery can be 35 mm or more, preferably 40 mm to 50 mm. The height of the cylindrical battery can be 70 mm or more, preferably 75 mm to 90 mm. A cylindrical battery according to an embodiment of the present invention can be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. The numerical values represent the form factor, the first two digits indicating the diameter of the battery, and the remaining digits indicating the height of the battery.

[0175] When an electrode assembly having a tabless structure is applied to a cylindrical battery with a form factor ratio greater than about 0.4, a relatively large stress is applied in the radial direction when the uncoated portion is bent, so the uncoated portion is likely to tear. In addition, when welding the current collector plate to the bent surface area of the uncoated portion, it is necessary to sufficiently increase the number of stacked layers of the uncoated portion in the bent surface area in order to sufficiently ensure the welding strength and reduce the resistance. This requirement can be achieved by the electrodes and electrode assemblies according to embodiments (variants) of the present invention.

[0176] A battery according to an embodiment of the present invention can be an approximately cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0177] A battery according to an embodiment of the present invention can be an approximately cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0178] A battery according to an embodiment of the present invention can be an approximately cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0179] A battery according to an embodiment of the present invention can be an approximately cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0180] A battery according to an embodiment of the present invention can be an approximately cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0181] The present invention is not limited to the above form factor ratio, diameter, and height of the cylindrical battery. Therefore, the present invention can also be applied to batteries having a form factor ratio of about 0.4 or less, such as 1865 batteries, 2170 batteries, etc.

[0182] In the following, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0183] Figure 12 FIG. 5 is a cross-sectional view taken along the winding axis direction Y of a cylindrical battery 190 according to an embodiment of the present invention.

[0184] Referring to Figure 12 , a cylindrical battery 190 according to an embodiment of the present invention includes an electrode assembly 110 having a first electrode, a separator, and a second electrode, a battery case 142 accommodating the electrode assembly 110, and a sealing body 143 sealing an open end of the battery case 142.

[0185] The battery case 142 is a cylindrical container having an opening at the top. The battery case 142 is made of a conductive metal material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery case 142. The battery case 142 accommodates the electrode assembly 110 in an internal space through the top opening and also accommodates an electrolyte.

[0186] The electrolyte may be a salt having, for example, an A + B - structure. Here, A + includes an alkali metal cation such as Li + , Na + , or K + , or a combination thereof. And B - includes at least one anion selected from the group consisting of: F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 -, (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - .

[0187] The electrolyte can also be dissolved in an organic solvent. The organic solvent can be propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0188] As Figure 2 shown, the electrode assembly 110 can have a wound core shape. The electrode assembly 110 can be manufactured by winding a laminate formed by laminating a lower separator, a first electrode, an upper separator, and a second electrode at least once.

[0189] The first electrode and the second electrode have different polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode can have the electrode structure of the above embodiments (variants). In addition, the other of the first electrode and the second electrode can have a conventional battery structure or the electrode structure of an embodiment (variant). The electrode pairs included in the electrode assembly 110 are not limited to one electrode pair and can include two or more electrode pairs.

[0190] The electrode assembly 110 can include curved surface regions F ( Figure 10a ) at the upper and lower portions. The first current collector 144 can be welded to the curved surface region F of the first uncoated portion 146a, and the second current collector 145 can be welded to the curved surface region F of the second uncoated portion 146b.

[0191] Preferably, more than 50% of the welding area W of the first current collector 144 and the second current collector 145 can overlap with the region S2 where the number of laminations of the curved surface region F is the same ( Figure 10c ). Optionally, the remaining region of the welding area W can overlap with the region S1 where the number of laminations of the curved surface region F increases ( Figure 10c)。In terms of high welding strength, low welding interface resistance, and prevention of damage to the separator or the active material layer, it is preferable that the entire welding region W overlaps with the region S2 where the number of stacked layers is the same ( Figure 10c )。

[0192] The core 112 of the electrode assembly 110 is not enclosed by the curved surface region F. Therefore, there is no difficulty in the electrolyte injection process, and the welding process between the second current collector plate 145 and the battery case 142 can be easily performed by inserting a welding jig through the core 112.

[0193] If, as Figure 10c shown, the width and / or height and / or separation distance of the section are adjusted to fall within the numerical range of the above-described embodiment, when the section is bent, the sections overlap at least 10 times or more to sufficiently ensure the welding strength, and no void space (gap) is formed in the curved surface region F.

[0194] The seal 143 may include a cover plate 143a, a first gasket 143b that provides airtightness and insulation between the cover plate 143a and the battery case 142, and a connection plate 143c that is electrically and mechanically joined to the cover plate 143a.

[0195] The cover plate 143a is a component formed of a conductive metal material and covers the top opening of the battery case 142. The cover plate 143a is electrically connected to the curved surface region F of the first electrode and is electrically insulated from the battery case 142 through the first gasket 143b. Therefore, the cover plate 143a can function as the first electrode (e.g., the positive electrode) of the cylindrical battery 190.

[0196] The cover plate 143a is placed on the flange portion 147 formed on the battery case 142 and is fixed by the crimping portion 148. A first gasket 143b may be provided between the cover plate 143a and the crimping portion 148 to ensure the airtightness of the battery case 142 and the electrical insulation between the battery case 142 and the cover plate 143a. The cover plate 143a may include a protrusion 143d that protrudes upward from its center.

[0197] The battery case 142 is electrically connected to the curved surface region F of the second electrode. Therefore, the polarity of the battery case 142 is the same as that of the second electrode. If the second electrode has a negative polarity, the battery case 142 also has a negative polarity.

[0198] The battery case 142 includes a flange portion 147 and a crimping portion 148 at its top. The flange portion 147 may be formed by pressing the outer peripheral surface of the battery case 142 inward. The flange portion 147 prevents the electrode assembly 110 accommodated inside the battery case 142 from moving out through the top opening of the battery case 142 and can function as a support portion for placing the seal 143.

[0199] The second part B3 of the first electrode does not include a section, and the height of the uncoated part of the second part B3 is lower than that of the third part B2. Therefore, even when the battery case 142 is pressed inward externally to form the flange part 147, the winding turns of the second part B3 are basically not affected. Accordingly, the winding turns of the second part B3 are not squeezed by other components (such as the flange part 147). Thereby, partial deformation of the electrode assembly 110 can be prevented, thus preventing a short circuit inside the cylindrical battery 190.

[0200] Preferably, when the inward pressing depth of the flange part 147 is defined as D1, and the radius length from the inner circumference of the battery case 142 to the boundary point between the second part B3 and the third part B2 is defined as D2, the relational expression D1 ≤ D2 can be satisfied. In this case, when the battery case 142 is pressed inward to form the flange part 147, damage to the winding turns of the second part B3 can be substantially prevented.

[0201] A crimping part 148 is formed on the flange part 147. The crimping part 148 has an extended and bent shape to cover the outer circumference of the cover plate 143a provided on the flange part 147 and a part of the upper surface of the cover plate 143a.

[0202] The cylindrical battery 190 may further include a first current collector plate 144 and / or a second current collector plate 145 and / or an insulator 146.

[0203] The first current collector plate 144 is joined to the upper part of the electrode assembly 110. The first current collector plate 144 is formed of a conductive metal material such as aluminum, copper, and nickel, and is electrically connected to the curved surface area F of the first electrode. The electrical connection can be completed by welding. A lead wire 149 can be connected to the first current collector plate 144. The lead wire 149 can extend upward from the electrode assembly 110 and can be joined to the connection plate 143c or can be directly joined to the lower surface of the cover plate 143a. The lead wire 149 can be connected to other components by welding.

[0204] Preferably, the first current collector plate 144 can be integrally formed with the lead wire 149. In this case, the lead wire 149 can have a long plate shape extending outward from near the center or edge of the first current collector plate 144.

[0205] The first current collector plate 144 and the curved surface area F of the first electrode can be joined by, for example, laser welding. The laser welding can be performed by melting the base material part of the current collector plate. In a variant, the first current collector plate 144 and the curved surface area F can be welded with solder provided therebetween. In this case, the solder can have a lower melting point compared to the first current collector plate 144 and the first uncoated part 146a. The laser welding can be replaced by resistance welding, ultrasonic welding, spot welding, etc.

[0206] The second current collector plate 145 is joined to the lower surface of the electrode assembly 110. One side of the second current collector plate 145 can be joined to the curved surface area F of the second electrode by welding, and the other side can be joined to the inner bottom surface of the battery case 142 by welding. The joining structure between the second current collector plate 145 and the curved surface area F of the second electrode can be substantially the same as the joining structure between the first current collector plate 144 and the curved surface area F of the first electrode.

[0207] The insulator 146 can cover the first current collector plate 144. The insulator 146 can cover the first current collector plate 144 at the upper surface thereof, thereby preventing direct contact between the first current collector plate 144 and the inner circumference of the battery case 142.

[0208] The insulator 146 includes a lead hole 151 such that the lead 149 extending upward from the first current collector plate 144 can be led out therefrom. The lead 149 is led out upward through the lead hole 151 and joined to the lower surface of the connection plate 143c or the lower surface of the cover plate 143a.

[0209] The peripheral area around the edge of the insulator 146 can be disposed between the first current collector plate 144 and the circular edge portion 147 to fix the joined body of the electrode assembly 110 and the first current collector plate 144. Thus, the movement of the joined body of the electrode assembly 110 and the first current collector plate 144 can be restricted in the height direction Y of the battery 190, thereby improving the assembly stability of the battery 190.

[0210] The insulator 146 can be formed of an insulating polymer resin. In one example, the insulator 146 can be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0211] The battery case 142 can further include an exhaust portion 152 formed at its lower surface. The exhaust portion 152 corresponds to a region that is thinner in thickness than the peripheral area in the lower surface of the battery case 142. The exhaust portion 152 is structurally weaker than the peripheral area. Thus, if an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a predetermined level, the exhaust portion 152 can rupture so that the gas generated inside the battery case 142 can be discharged to the outside. The internal pressure at which the exhaust portion 152 ruptures can be about 15 kgf / cm 2 to 35 kgf / cm 2 .

[0212] The exhaust portion 152 can be formed continuously or discontinuously while drawing a circle at the lower surface of the battery case 142. In one variant, the exhaust portion 152 can be formed in a straight line pattern or other pattern.

[0213] Figure 13FIG. 0 is a cross-sectional view of the cylindrical battery 200 according to an embodiment of the present invention taken along the winding axis direction Y.

[0214] Referring to Figure 13 , the structure of the electrode assembly of the cylindrical battery 200 according to an embodiment of the present invention is substantially the same as that of the cylindrical battery 190 in Figure 12 , and other structures except for the electrode assembly are changed.

[0215] Specifically, the cylindrical battery 200 includes a battery case 171, and a riveting terminal 172 is installed through the battery case 171. The riveting terminal 172 is installed through a through hole formed in the closed end of the battery case 171. The riveting terminal 172 is riveted to the through hole of the battery case 171 with a second gasket 173 made of an insulating material disposed therebetween. The riveting terminal 172 is exposed to the outside in a direction opposite to the direction of gravity.

[0216] The riveting terminal 172 includes a terminal exposed portion 172a and a terminal insertion portion 172b. The terminal exposed portion 172a is exposed outside the closed surface of the battery case 171. The terminal exposed portion 172a may be located near the central portion of the closed end of the battery case 171. The maximum diameter of the terminal exposed portion 172a may be larger than the maximum diameter of the through hole formed in the battery case 171. The terminal insertion portion 172b may be electrically connected to the non-coated portion 146a of the first electrode through the central portion near the closed end of the battery case 171. The lower edge of the terminal insertion portion 172b may be riveted to the inner surface of the battery case 171. That is, the lower edge of the terminal insertion portion 172b may have a shape bent toward the inner surface of the battery case 171. A flat portion 172c is included inside the lower edge of the terminal insertion portion 172b. The maximum diameter of the lower portion of the riveted terminal insertion portion 172b may be larger than the maximum diameter of the through hole of the battery case 171.

[0217] The flat portion 172c of the terminal insertion portion 172b may be welded to the central portion of the first current collector 144 connected to the curved surface region F of the first electrode. The welding may be replaced by other welding methods such as ultrasonic welding.

[0218] An insulator 174 made of an insulating material may be disposed between the first current collector 144 and the inner surface of the battery case 171. The insulator 174 covers the upper portion of the first current collector 144 and the top edge of the electrode assembly 110. Therefore, it can prevent the second part B3 of the electrode assembly 110 from contacting the inner surface of the battery case 171 having a different polarity and causing a short circuit.

[0219] The thickness of the insulator 174 corresponds to or is slightly greater than the distance between the upper surface of the first current collector plate 144 and the inner surface of the closed portion of the battery case 171. Thus, the insulator 174 can be in contact with the upper surface of the first current collector plate 144 and the inner surface of the closed portion of the battery case 171.

[0220] The terminal insertion portion 172b of the riveted terminal 172 can pass through the through hole of the insulator 174 and be welded to the first current collector plate 144. The diameter of the through hole formed in the insulator 174 can be greater than the diameter of the riveted portion at the lower end of the terminal insertion portion 172b. Preferably, the through hole can expose the lower portion of the terminal insertion portion 172b and the second gasket 173.

[0221] The second gasket 173 is disposed between the battery case 171 and the riveted terminal 172 to prevent the battery case 171 and the riveted terminal 172 having opposite polarities from being in electrical contact with each other. Thus, the upper surface of the battery case 171 having a substantially flat shape can function as the second electrode (e.g., negative electrode) of the cylindrical battery 200.

[0222] The second gasket 173 includes a gasket exposure portion 173a and a gasket insertion portion 173b. The gasket exposure portion 173a is disposed between the terminal exposure portion 172a of the riveted terminal 172 and the battery case 171. The gasket insertion portion 173b is disposed between the terminal insertion portion 172b of the riveted terminal 172 and the battery case 171. The gasket insertion portion 173b can be deformed together when the terminal insertion portion 172b is riveted, so as to be in close contact with the inner surface of the battery case 171. For example, the second gasket 173 can be formed of a polymer resin having insulation properties, for example.

[0223] The gasket exposure portion 173a of the second gasket 173 can have an extended shape to cover the outer periphery of the terminal exposure portion 172a of the riveted terminal 172. When the second gasket 173 covers the outer periphery of the riveted terminal 172, a short circuit can be prevented when an electrical connection component (e.g., a bus bar) is joined to the upper surface of the battery case 171 and / or joined to the riveted terminal 172. Although not shown in the figure, the gasket exposure portion 173a can have an extended shape that covers not only the outer peripheral surface of the terminal exposure portion 172a but also a part of its upper surface.

[0224] When the second gasket 173 is formed of a polymer resin, the second gasket 173 can be heat fusion bonded to the battery case 171 and the riveted terminal 172. In this case, the airtightness at the bonding interface between the second gasket 173 and the riveted terminal 172 and at the bonding interface between the second gasket 173 and the battery case 171 can be enhanced. At the same time, when the gasket exposure portion 173a of the second gasket 173 has a shape extending to the upper surface of the terminal exposure portion 172a, the riveted terminal 172 can be integrally joined to the second gasket 173 by insert injection molding.

[0225] In the upper surface of the battery case 171, the remaining area 175 except for the area occupied by the riveted terminal 172 and the second gasket 173 corresponds to the second electrode terminal having a polarity opposite to that of the riveted terminal 172.

[0226] The second current collector plate 176 is joined to the lower part of the electrode assembly 110. The second current collector plate 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the curved surface area F of the second electrode.

[0227] Preferably, the second current collector plate 176 is electrically connected to the battery case 171. For this purpose, at least a part of the edge of the second current collector plate 176 may be provided and fixed between the inner surface of the battery case 171 and the first gasket 178b. In one example, at least a part of the edge of the second current collector plate 176 may be supported on the lower surface of the circular edge portion 180 formed at the bottom of the battery case 171 and fixed to the circular edge portion 180 by welding. In a variant, at least a part of the edge of the second current collector plate 176 may be directly welded to the inner wall surface of the battery case 171.

[0228] Preferably, the second current collector plate 176 and the curved surface area F of the second electrode may be joined by welding (e.g., laser welding). In addition, the welding areas of the second current collector plate 176 and the curved surface area F may be separated at a predetermined interval based on the inner circumferential core portion C of the circular edge portion 180.

[0229] The seal 178 that seals the lower open end of the battery case 171 includes a cover plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cover plate 178a from the battery case 171. The crimping portion 181 fixes the edge of the cover plate 178a and the first gasket 178b together. The cover plate 178a has an exhaust portion 179. The structure of the exhaust portion 179 is substantially the same as that of the above-described embodiment (variant). The lower surface of the cover plate 178a may be located above the lower end of the crimping portion 181. In this case, a space is formed below the cover plate 178a to facilitate exhaust. In particular, this is useful when the cylindrical battery 200 is installed such that the crimping portion 181 faces the direction of gravity.

[0230] Preferably, the cover plate 178a is formed of a conductive metal material. However, since the first gasket 178b is provided between the cover plate 178a and the battery case 171, the cover plate 178a may not have an electrode polarity. The seal 178 seals the lower open end of the battery case 171 and mainly functions to discharge gas when the internal pressure of the battery 200 exceeds a critical value. The pressure threshold may be 15 kgf / cm 2 to 35 kgf / cm 2 .

[0231] Meanwhile, in a variant example, the battery case 171 may not include the flange portion 180 and the crimping portion 181. In this case, the side wall of the battery case 171 may extend in a straight line, and the edge of the cover plate 178a may be directly joined to the open end of the battery case 171. The edge of the cover plate 178a may be welded to the open end of the battery case 171. In this variant example, the first gasket 178b may be omitted.

[0232] In a variant example, at least a part (e.g., the edge portion) of the second current collector plate 176 may be joined to the cover plate 178a.

[0233] In another variant example, at least a part (e.g., the edge portion) of the second current collector plate 176 may be bent to face the inner surface of the side wall of the battery case 171, and the bent portion may be joined to the inner surface of the side wall of the battery case 171 by welding.

[0234] In yet another variant example, the edge of the cover plate 178a, the open end of the battery case 171, and the edge portion of the second current collector plate 176 may be integrally joined by welding.

[0235] In yet another variant example, the inner region of the edge portion of the cover plate 178a may be directly welded to the bent surface region F of the second electrode. In this case, the cover plate 178a functions to electrically connect the second electrode to the battery case 171, so the second current collector plate 176 may be omitted.

[0236] Preferably, the riveting terminal 172 electrically connected to the bent surface region F of the first electrode is used as the first electrode terminal. In addition, in the upper surface of the battery case 171 that is electrically connected to the second uncoated portion 146b of the second electrode through the second current collector plate 176, the portion 175 other than the riveting terminal 172 serves as a second electrode terminal having a polarity different from that of the first electrode terminal. If the two electrode terminals are located at the upper part of the cylindrical battery 200 as described above, electrical connection components such as bus bars may be arranged only on one side of the cylindrical battery 200. This can simplify the battery pack structure and improve the energy density. In addition, since the portion 175 serving as the second electrode terminal has an approximately flat shape, a joining area sufficient to join electrical connection components such as bus bars can be ensured. Therefore, the cylindrical battery 200 can reduce the resistance at the connection portion of the electrical connection components to a desired level.

[0237] The above-described cylindrical battery can be used to manufacture a battery pack.

[0238] Figure 14 is a diagram schematically showing a battery pack according to an embodiment of the present invention.

[0239] Refer to Figure 14, a battery pack 300 according to an embodiment of the present invention includes: a cluster formed by electrically connecting cylindrical batteries 301, and a battery pack housing 302 that houses the cluster. The cylindrical battery 301 can be any one of the batteries in the above-described embodiment (variant). In the drawings, for ease of illustration, components such as bus bars for electrically connecting the cylindrical batteries 301, a cooling unit, and external terminals are not depicted.

[0240] The battery pack 300 can be installed in a vehicle. For example, the vehicle can be an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle.

[0241] Figure 15 is a diagram schematically showing a vehicle Figure 14 including the battery pack 300.

[0242] Referring to Figure 15 , a vehicle V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The vehicle V operates by receiving electrical energy from the battery pack 300 according to an embodiment of the present invention.

[0243] According to the present invention, by improving the end structure of the section, a gap serving as an electrolyte impregnation path can be formed in a curved surface area formed by bending the section in the radial and / or circumferential directions, thereby shortening the electrolyte impregnation time.

[0244] According to another aspect of the present invention, by improving the structure of the uncoated portion of the electrode assembly, interference between the electrode assembly and the inner circumference of the battery case during the formation of the circular edge portion of the battery case can be prevented, and short circuits inside the cylindrical battery due to partial deformation of the electrode assembly can be prevented.

[0245] According to still another aspect of the present invention, by applying a structure in which a current collector plate is welded to a wide area of a curved surface area formed by bending the section, an electrode assembly having improved energy density and lower resistance can be provided.

[0246] According to still another aspect of the present invention, by improving the structure of the uncoated portion adjacent to the core of the electrode assembly, blockage of the cavity in the core of the electrode assembly can be prevented when the uncoated portion is bent, and thus the electrolyte injection process and the process of welding the battery case (or riveting the terminal) and the current collector plate can be easily performed.

[0247] According to still another aspect of the present invention, a cylindrical battery having a structure that improves electrolyte impregnation, has a low internal resistance, prevents internal short circuits, and improves the welding strength between the current collector plate and the uncoated portion can be provided, and a battery pack and a vehicle including the cylindrical battery are also provided.

[0248] The present invention has been described in detail. However, it should be understood that the specific embodiments and specific examples, although indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the scope of the present invention will become apparent to those skilled in the art from this specific embodiment.

Claims

1. An electrode assembly, wherein a first electrode, a second electrode, and a separator disposed therebetween are wound around an axis to define a core portion and an outer periphery, Among them, at least one of the first electrode and the second electrode includes an uncoated portion extending along a long side end thereof in a winding direction, wherein the uncoated portion includes a plurality of sections separated by slits formed in the winding direction and bendable independently, wherein the plurality of sections bend toward the core portion to form a bent surface region at one end of the electrode assembly, and wherein at least a part of the plurality of sections includes folded ends.

2. The electrode assembly according to claim 1, Among them, when a section including the folded end is defined as an end-folded section, the bent surface region includes a plurality of end-folded sections, and wherein when the number of uncoated portions intersecting with an imaginary line passing through the center of the folded end is defined as the fold number of the folded end, the fold number of the folded end is 2 or more, and a gap is formed between adjacent sections in a radial direction of the electrode assembly.

3. The electrode assembly according to claim 2, Among them, the gap has a separation distance corresponding to a thickness of the folded end between adjacent sections in the radial direction of the electrode assembly.

4. The electrode assembly according to claim 2, Among them, the plurality of end-folded sections are arranged in a regular or irregular pattern on the bent surface region in the radial direction or circumferential direction of the electrode assembly.

5. The electrode assembly according to claim 2, Among them, the bent surface region includes a radial region in which the number of end-folded sections arranged in a circumferential direction increases stepwise or gradually from the core portion toward the outer periphery.

6. The electrode assembly according to claim 2, Among them, the bent surface region includes a radial region in which the fold number of the folded end increases stepwise or gradually from the core portion toward the outer periphery.

7. The electrode assembly according to claim 2, Among them, the bent surface region includes a radial region in which the fold number of the folded end remains consistent from the core portion toward the outer periphery.

8. The electrode assembly according to claim 2, Among them, the height of the plurality of end-folded sections increases stepwise from the core portion toward the outer periphery of the electrode assembly, wherein the bent surface region includes a radial region in which the fold number of the folded end increases as the height of the end-folded section increases.

9. The electrode assembly according to claim 2, Among them, the bent surface region includes a radial region in which a width of the uncoated portion forming the folded end in a direction of the one axis increases stepwise or gradually from the core portion to the outer periphery of the electrode assembly.

10. The electrode assembly according to claim 2, Among them, at any point of the bent surface region, when the number of uncoated portions intersecting with an imaginary line parallel to the direction of the one axis and passing through the bent surface region is defined as the stacking number of the uncoated portion at the corresponding point, from the outer periphery to the core portion of the electrode assembly, the bent surface region includes a stacking number increasing region and a stacking number consistent region, and Among them, the number of end folding sections included in the stacking number increasing area is greater than the number of end folding sections included in the stacking number consistent area.

11. The electrode assembly according to claim 2, Among them, At any point in the curved surface area, if the number of uncoated parts intersecting with an imaginary line passing through the curved surface area in the direction parallel to the one axis is defined as the stacking number of the uncoated parts at the corresponding point, then from the outer periphery to the core of the electrode assembly, the curved surface area includes a stacking number increasing area and a stacking number consistent area, and Among them, the folding number of the folded ends included in the stacking number consistent area is greater than the folding number of the folded ends included in the stacking number increasing area.

12. The electrode assembly according to claim 1, Among them, The folded end has a structure folded into a bobbin shape, a structure folded into a zigzag shape, or a randomly folded structure.

13. A cylindrical battery, comprising: The electrode assembly according to any one of claims 1 to 12; A battery case, the battery case having an open end and a closed end and being configured to accommodate the electrode assembly through the open end, the battery case being electrically connected to the second electrode of the electrode assembly; A sealing body, the sealing body being configured to seal the open end of the battery case; And A terminal, the terminal being electrically connected to the first electrode of the electrode assembly and having a surface exposed outside the battery case.

14. The cylindrical battery according to claim 13, Among them, The curved surface area is formed by bending a plurality of sections included in the uncoated part of the first electrode, and Among them, the cylindrical battery further includes a first current collector plate that electrically connects the curved surface area to the terminal.

15. The cylindrical battery according to claim 13, Among them, The terminal is installed in a through hole formed in the closed end of the battery case to be insulated from the battery case, Among them, the terminal includes a terminal exposed part exposed through the outer surface of the closed end, and a terminal insertion part extending from the terminal exposed part and inserted into the battery case through the through hole, and Among them, the lower edge of the terminal insertion part is riveted to the inner surface of the closed end.

16. The cylindrical battery according to claim 13, Among them, The sealing body includes a cover plate that seals the open end of the battery case, and The terminal is the cover plate.

17. The cylindrical battery according to claim 13, Among them, The curved surface area is formed by bending the plurality of sections included in the uncoated part of the second electrode, and Among them, the cylindrical battery further includes a second current collector plate that electrically connects the curved surface area to the side wall of the battery case.

18. The cylindrical battery according to claim 17, Among them, The sealing body includes: a cover plate configured to cover the open end of the battery case, and a gasket provided between the edge of the cover plate and the open end, and Among them, the edge of the second current collector plate is provided between the gasket and the side wall of the battery case.

19. The cylindrical battery according to claim 18, Among them, The battery case includes a flange portion formed by pressing the outer periphery near the open end inward, and wherein, an edge of the cover plate contacts the flange portion.

20. The cylindrical battery according to claim 13, Among them, the sealing body includes a cover plate configured to cover the open end of the battery case, and an edge of the cover plate is joined to the open end.

21. The cylindrical battery according to claim 20, Among them, at least a part of the cover plate is joined to the curved surface area of the electrode assembly.

22. A battery pack, comprising a plurality of the cylindrical batteries according to any one of claims 13 to 21.

23. A vehicle, comprising the battery pack according to claim 22.

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