Current collector for secondary battery and cylindrical battery cell containing the same

Abstract

The present invention discloses a current collector for a secondary battery and a cylindrical battery cell containing the same. The current collector for a secondary battery is characterized in that the elongation is 1.5% to 3.0%, the tensile strength is 25kgf / mm 2 Up to 35kgf / mm 2 According to the present invention, since the elongation and tensile strength of the current collector are optimally set, the arch length is reduced to less than 20 mm when manufacturing the electrode plate, and there are no bending or breaking defects during the jelly roll winding process.

Description

Technical Field

[0001] The present invention relates to a current collector for a secondary battery and a battery cell comprising the current collector, and also relates to a battery pack and a vehicle comprising the battery cell. Background Art

[0002] With the development of technology and the increase in demand for mobile devices and electric vehicles, the demand for secondary batteries as energy sources is rapidly increasing. Currently, the widely used secondary batteries are lithium-ion batteries, and the operating voltage of a unit battery cell is about 2.5V to 4.5V. When a higher output voltage is required, a battery pack is formed by connecting multiple battery cells in series, or by connecting multiple battery cells in parallel according to the required charge / discharge capacity of the battery pack.

[0003] As types of unit battery cells, cylindrical, prismatic, and pouch types are well known. The cylindrical battery cell includes a jelly roll type electrode assembly. The jelly roll type electrode assembly has a structure in which a positive electrode plate and a negative electrode plate having a sheet shape are wound with a separator interposed therebetween.

[0004] Figure 1 is a plan view showing the structure of the electrode plate, Figure 2 is a view showing an electrode plate winding process for manufacturing a jelly-roll type electrode assembly.

[0005] refer to Figure 1 and Figure 2 The positive electrode plate 10 and the negative electrode plate 11 have a structure in which an active material layer 21 is coated on a sheet-like current collector 20 and may include an uncoated portion 22 on a long side along a winding direction X. Figure 2 As shown, the electrode assembly is manufactured by sequentially stacking the positive electrode plate 10 and the negative electrode plate 11 with two separators 12 and then winding them around a core in one direction X. In this case, the uncoated portions 22 of the positive electrode plate 10 and the negative electrode plate 11 may be arranged in opposite directions.

[0006] The positive electrode plate 10 and the negative electrode plate 11 may include a current collector 20 elongated along a winding direction X and an active material layer 21 coated on an upper surface and / or a lower surface of the current collector 20. The end of the current collector 20 is not coated with the active material layer 21 in a predetermined width. In the art, the area not coated with the active material layer 21 is referred to as an uncoated portion 22, and the area coated with the active material coating layer 21 is referred to as a coated portion.

[0007] The electrode plate manufacturing process includes the steps of coating the active material layer 21 onto the current collector 20 to a designed thickness, drying the coated active material layer 21, and laminating the active material layer to a desired density through a rolling process using a roller.

[0008] Figure 3 is a schematic diagram showing a process of rolling an electrode plate using a roller.

[0009] refer to Figure 3 , the electrode plate 1 coated with the active material layer 21 on the upper and lower surfaces of the current collector 20 is rolled while passing between a pair of rollers 30. Therefore, it can be seen that the deformation force that substantially stretches the electrode plate 1 acts in the longitudinal direction of the electrode plate 1 (with respect to the longitudinal direction of the electrode plate 1). Figure 1 When the active material layer 21 is compressed, the coated portion and the uncoated portion 22 have different elongations.

[0010] Therefore, the actual electrode plate 1 deviates Figure 1 The ideal shape is shown in Figure 4 As shown in (a), unlike the state before compression, after the rolling process is performed as shown in (b), the longitudinal direction (moving direction of the roller 30) of the electrode plate 1 expands, resulting in the following Figure 5 The buckling phenomenon is shown. The buckling phenomenon refers to a phenomenon in which the electrode plate 1 bends toward the uncoated portion 22 when the electrode plate 1 is unfolded according to the difference in elongation between the uncoated portion 22 and the coated portion.

[0011] The elongation is defined as shown in Formula 1 below.

[0012] [Equation 1]

[0013]

[0014] In other words, the elongation is expressed as a percentage of the elongation when an object of length L is deformed to a length L'. Elongation refers to the ratio at which a material stretches in a tensile test. The greater the elongation, the higher the tensile property without breaking due to external impact. That is, the elongation is used as a measure of the fracture performance of a material. Therefore, a material with a smaller elongation has a greater tendency to break due to external impact, while a material with a larger elongation has a greater tendency to stretch without breaking due to external impact.

[0015] For reference, the camber length is defined as the maximum value of the deformation measured at each point on the lower end of the electrode plate 1 when the expanded electrode plate 1 is unfolded along a straight line. The maximum value corresponds to the deformation measured at the end of the rolling process of the active material layer 21 (referred to as the "camber length"), such as Figure 5 shown.

[0016] If the electrode plate 1 with the camber is used as it is, a bending defect may be caused in the cutting operation of the uncoated portion 22 or in the winding process of the electrode plate 1. In addition, the bending defect may cause an internal short circuit between the positive electrode plate 10 and the negative electrode plate 11 facing each other with the separator 12 interposed therebetween in the jelly-roll type electrode assembly.

[0017] Generally, in order to reduce the difference in elongation between the uncoated portion 22 and the coated portion, the active material loading of the coated portion can be reduced, or the electrode plate 1 can be subjected to additional heat treatment after rolling. However, when the active material loading is reduced, the energy density is reduced. Additional heat treatment complicates the process and increases costs.

[0018] Therefore, in the technical field to which the present invention belongs, there is a need for a technology that can minimize the buckling phenomenon of the active material layer during the rolling process by controlling the physical properties of the current collector itself. Summary of the invention

[0019] Technical issues

[0020] The present invention is designed to solve the problems of the related art. Therefore, the present invention aims to provide a current collector for a secondary battery, which can alleviate the arching phenomenon in the manufacturing process of an electrode plate by controlling the elongation and tensile strength.

[0021] Another object of the present invention is to provide an electrode plate including a current collector, and an electrode assembly, a battery cell, a battery pack, and a vehicle including the electrode plate.

[0022] The problems to be solved by the present invention are not limited to the above-mentioned problems, and other unmentioned problems will be clearly understood by ordinary technicians in the field to which the present invention belongs from the following disclosure.

[0023] Technical Solution

[0024] The current collector for a secondary battery of the present invention for solving the above problems is characterized in that the elongation is 1.5% to 3.0%, the tensile strength is 25 kgf / mm 2 Up to 35kgf / mm 2 .

[0025] As is known to all, tensile strength and elongation are values ​​obtained by a tensile strength test based on IPC-TM-650. In particular, they can be measured by the IPC-TM-600 (2.4.19) method.

[0026] Preferably, the current collector is an aluminum current collector.

[0027] The present invention also provides an electrode plate for a secondary battery, which includes the above-mentioned current collector for a secondary battery. The electrode plate for a secondary battery of the present invention includes: a current collector for a secondary battery, wherein the elongation is 1.5% to 3.0%, and the tensile strength is 25 kgf / mm 2 Up to 35kgf / mm 2 ; and an active material layer formed on the current collector.

[0028] The current collector may have a sheet shape having short sides and long sides, and may include an uncoated portion where the active material layer is not coated at an end of the long side of the current collector.

[0029] The width of the electrode plate along the short side of the current collector may be 60 mm to 110 mm, the length of the electrode plate along the long side of the current collector may be 3 m to 5 m, and the arch length of the electrode plate may be less than 20 mm.

[0030] Preferably, the length of the uncoated portion measured along the short side direction of the current collector may be 2 mm to 20 mm. The length of the uncoated portion is the length measured in the width direction of the current collector. The width direction of the current collector is perpendicular to the longitudinal direction of the current collector.

[0031] At least a portion of the area of ​​the uncoated portion may be divided into a plurality of sections.

[0032] At this time, the uncoated portion may have a cutout in a direction along a short side of the current collector.

[0033] Preferably, the uncoated portion of the cutout area has no breaks or cracks.

[0034] The energy density per unit area of ​​the active material layer is 1 mAh / cm 2 Up to 6mAh / cm 2 .

[0035] The current collector may be an aluminum current collector, and the active material may include a lithium transition metal oxide. As described above, the electrode plate may be a positive electrode plate.

[0036] The electrode assembly of the present invention is a jelly roll type electrode assembly, in which a first electrode plate and a second electrode plate in a sheet shape and a separator interposed therebetween are wound in one direction, wherein at least one of the first electrode plate and the second electrode plate includes a current collector, and an uncoated portion at the end of the long side of the current collector is provided with an uncoated portion on which an active material layer is not coated, wherein at least a portion of the uncoated portion is exposed to the outside of the separator and serves as an electrode tab itself, and wherein the current collector has an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 Up to 35kgf / mm 2 .

[0037] Preferably, in the electrode assembly, the current collector may be an aluminum current collector, the width of the first electrode plate or the second electrode plate along the short side of the current collector may be 60 mm to 110 mm, the length of the first electrode plate or the second electrode plate along the long side of the current collector may be 3 m to 5 m, and the arch length of the first electrode plate or the second electrode plate may be less than 20 mm.

[0038] In the electrode assembly, the uncoated portion may include a core-side uncoated portion adjacent to the core of the electrode assembly, a peripheral uncoated portion adjacent to the peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the peripheral uncoated portion, and at least a portion of the intermediate uncoated portion may be divided into multiple segments.

[0039] The segment may have a shape in which an upper width is smaller than a lower width.

[0040] In one aspect, each of the plurality of segments may have a rectangular, trapezoidal, triangular, parallelogram, semicircular, or semi-elliptical structure, and the peripheral uncoated portion and the core-side uncoated portion may not have a segment structure in the uncoated portion.

[0041] In another aspect, at least one side forming the periphery of the segment can be deformed into a curved shape, and the shape of its apex can also be deformed into a circle.

[0042] In another aspect, the segments may have a shape in which the width of the lower portion is greater than the width of the upper portion, and the width may decrease gradually and / or stepwise from the lower portion to the upper portion.

[0043] The plurality of segments may be bent, for example, toward the core, in the radial direction of the electrode assembly and overlapped in several layers.

[0044] There are no breaks or cracks between the multiple segments.

[0045] The cylindrical battery cell of the present invention comprises: a jelly-roll type electrode assembly in which a first electrode plate and a second electrode plate in a sheet shape and a separator inserted therebetween are wound in one direction; a battery case configured to accommodate the battery assembly and electrically connected to any one of the first electrode plate and the second electrode plate to have a first polarity; a seal configured to seal the open end of the battery case; and a terminal electrically connected to the other of the first electrode plate and the second electrode plate to have a second polarity and having a surface exposed to the outside, wherein at least one of the first electrode plate and the second electrode plate comprises a current collector having an uncoated portion at the end of the long side of the current collector where the active material layer is not coated, wherein at least a portion of the uncoated portion is exposed to the outside of the separator and serves as an electrode tab itself, and wherein the current collector has an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 Up to 35kgf / mm 2 .

[0046] In a cylindrical battery cell, the uncoated portion may include a core side uncoated portion adjacent to the core of the electrode assembly, a peripheral uncoated portion adjacent to the peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core side uncoated portion and the peripheral uncoated portion, and at least a portion of the intermediate uncoated portion may be divided into multiple segments.

[0047] At least a portion of the middle uncoated portion may be bent from the periphery toward the core, a cavity may be provided in the core of the electrode assembly, and the cavity may not be closed by the bent structure of the middle uncoated portion.

[0048] The cylindrical battery cell may further include a current collecting plate electrically connected to an uncoated portion of the second electrode plate having the first polarity and configured to connect at least a portion of an edge thereof to a side wall of the battery case.

[0049] The seal may include a non-polar cover plate and a gasket that is crimped around the edge of the cover plate to the top of the battery case.

[0050] The battery case may include a rivet terminal installed to be insulated in a through hole formed in a central portion of the closed surface and electrically connected to the first electrode plate to have the second polarity.

[0051] The technical problem of the present invention is also achieved by a battery comprising at least one cylindrical battery cell as described above and a vehicle comprising at least one battery.

[0052] Beneficial effects

[0053] According to one aspect of the present invention, the elongation and tensile strength of the current collector are optimally adjusted, so that the occurrence of arching in the electrode plate manufactured using the corresponding current collector can be minimized, and thus when the jelly roll type electrode assembly is manufactured using the corresponding electrode plate, the occurrence of bending defects can be prevented.

[0054] Since the current collector of the present invention optimally adjusts the elongation and tensile strength, even if the active material layer is pattern-coated in a strip shape on a large-area current collector and rolled, expansion does not occur. Therefore, it is easy to cut along the uncoated portion between the pattern-coated active material layers, and is very suitable for producing a large number of electrode plates with minimal camber.

[0055] The current collector of the present invention is suitable for manufacturing large batteries. In particular, the current collector of the present invention is suitable for manufacturing cylindrical secondary batteries, wherein the positive electrode uncoated portion and the negative electrode uncoated portion are located at the top and bottom of the jelly roll type electrode assembly, respectively, and the current collector is welded to the uncoated portion to have a structure with improved current collection efficiency, i.e., a so-called tab-free cylindrical secondary battery. Such a jelly roll type electrode assembly can be manufactured, including the steps of cutting and bending the uncoated portion. Here, the current collector of the present invention can minimize the segment disconnection when cutting the uncoated portion, which is beneficial to the cutting process.

[0056] According to another aspect of the present invention, by using the uncoated portions themselves protruding from the upper and lower portions of the electrode assembly as electrode tabs, the internal resistance of the battery cell may be reduced and the energy density may be increased.

[0057] According to another aspect of the present invention, a short circuit in a cylindrical battery cell caused by partial deformation of the electrode assembly can be prevented by improving the structure of the uncoated portion of the electrode assembly so that the electrode assembly and the inner circumferential surface of the battery shell do not interfere with the process of forming the curling portion of the battery shell.

[0058] According to another aspect of the present invention, tearing of the uncoated portion when bent can be prevented by improving the structure of the uncoated portion of the electrode assembly, and welding strength can be improved by sufficiently increasing the number of overlapping layers of the uncoated portion.

[0059] According to another aspect of the present invention, by improving the structure of the uncoated portion adjacent to the core of the electrode assembly to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, the electrolyte injection process and the welding process of the battery case and the current collecting plate can be easily performed.

[0060] According to another aspect of the present invention, a cylindrical battery cell having a structure in which internal resistance is low, internal short circuit is prevented, and welding strength of a current collecting plate and an uncoated portion is improved, and a battery pack and a vehicle including the same can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings illustrate preferred embodiments of the present invention, and together with the above disclosure are used to provide a further understanding of the technical features of the present invention. Therefore, the present invention is not interpreted as being limited to the accompanying drawings.

[0062] Figure 1 It is a plan view illustrating the structure of the electrode plate.

[0063] Figure 2 is a view showing an electrode plate winding process for manufacturing a jelly-roll type electrode assembly.

[0064] Figure 3 Schematic diagram for explaining a process of rolling an electrode plate using a roller.

[0065] Figure 4 is a view explaining a phenomenon that expansion occurs in a longitudinal direction of an electrode plate when an active material layer coated on a current collector is compressed according to the related art.

[0066] Figure 5 3 is a diagram illustrating a buckling phenomenon in which an electrode plate is bent toward an uncoated portion when the expanded electrode plate is unfolded along a straight line.

[0067] Figure 61 is a plan view showing the structure of an electrode plate according to a first embodiment manufactured using a current collector according to an embodiment of the present invention.

[0068] Figure 7 It is a plan view showing the electrode plate structure according to the second embodiment of the present invention.

[0069] Figure 8 It is shown Figure 7 Diagram of the definition of segment width, height and spacing in the electrode plate.

[0070] Fig. 9 This is a photo of the test results, which confirmed whether cracking caused by operating tension occurred depending on the spacing and shape of the segments.

[0071] Fig.10 It is a plan view showing the structure of an electrode plate according to a third embodiment of the present invention.

[0072] Fig.11 It is shown Fig.10 Diagram of the definition of segment width, height and spacing in the electrode plate.

[0073] Fig.12 are photographs comparatively showing a buckling phenomenon occurring when an electrode plate is manufactured using a current collector having the best elongation and tensile strength according to an embodiment of the present invention and when an electrode plate is manufactured using a current collector of the related art.

[0074] Fig.13 It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of a jelly-roll type electrode assembly, in which the electrode plate of the first embodiment is applied to a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate).

[0075] Fig.14 It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of a jelly-roll type electrode assembly, in which any one electrode plate of the second to third embodiments (variations thereof) is applied to a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate).

[0076] Fig.15 This is a cross-sectional view taken along the Y-axis direction (winding axis direction) of an electrode assembly according to another embodiment of the present invention.

[0077] Fig.16 is a cross-sectional view taken along the Y-axis direction, which shows a cylindrical battery cell according to an embodiment of the present invention.

[0078] Fig.17 is a cross-sectional view taken along the Y-axis direction, which shows a cylindrical battery cell according to another embodiment of the present invention.

[0079] Fig.18Schematic diagram of a battery pack configuration according to an embodiment of the present invention.

[0080] Fig.19 1 is a diagram schematically showing a vehicle including a battery pack according to an embodiment of the present invention. DETAILED DESCRIPTION

[0081] The preferred embodiments of the present invention will be described in detail below 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 interpreted as limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention based on the principle of allowing the inventor to appropriately define the terms to obtain the best interpretation.

[0082] Therefore, the descriptions presented herein are only preferred examples for illustrative purposes and are not intended to limit the scope of the present invention, and it should be appreciated that other equivalents and modifications may be made thereto without departing from the scope of the present invention.

[0083] In addition, to help understand the present invention, the accompanying drawings are not drawn to scale, but the sizes of some components may be exaggerated. In addition, in different embodiments, the same reference numerals may refer to the same components.

[0084] The current collector of the present invention is characterized in that the elongation is 1.5% to 3.0% and the tensile strength is 25kgf / mm 2 Up to 35kgf / mm 2 As is known, tensile strength and elongation are values ​​obtained by a tensile strength test based on IPC-TM-650. In particular, tensile strength and elongation can be measured by the IPC-TM-600 (2.4.19) method. The current collector of the present invention is characterized in that the elongation measured by the IPC-TM-600 (2.4.19) method is 1.5% to 3.0%, and the tensile strength is 25kgf / mm 2 Up to 35kgf / mm 2 .

[0085] Considering that the typical elongation of materials used as conventional current collectors is 10% to 15%, the current collector of the present invention has a very low elongation. The tensile strength is a value obtained by dividing the maximum tensile load before the specimen breaks by the cross-sectional area of ​​the specimen before the material tensile test. Depending on the manufacturing method, the tensile strength of pure aluminum foil is generally 50Mpa to 100Mpa, i.e. 5.1kgf / mm 2 Up to 10.2kgf / mm 2 (1kgf=9.8N,N / mm 2 =Mpa). In view of this, the current collector of the present invention has high tensile strength.

[0086] The current collector of the present invention can be used as a current collector for a secondary battery. The current collector can be coated with an active material layer. The current collector of the present invention can be used as a current collector in the manufacture of a positive electrode plate and a negative electrode plate of a jelly roll type electrode assembly. Hereinafter, the current collector of the present invention will be described in more detail by describing an electrode plate including such a current collector.

[0087] Figure 6 1 is a plan view showing the structure of an electrode plate according to a first embodiment manufactured using a current collector according to an embodiment of the present invention.

[0088] The electrode plate 50 includes a current collector 41 and an active material layer 42. The current collector 41 is appropriately selected according to the polarity of the electrode plate 50. As a material of the current collector 41, aluminum, copper, nickel or stainless steel can be used, but the present invention is not limited thereto, and metals and metal alloys used as current collector materials can be used. For example, when the current collector 41 is an aluminum current collector, it is used as a positive electrode current collector in a secondary battery, the active material layer 42 is a positive electrode active material layer, and the electrode plate 50 is a positive electrode plate. When the current collector 41 is a copper current collector, it is used as a negative electrode current collector in a secondary battery, the active material layer 42 is a negative electrode active material layer, and the electrode plate 50 is a negative electrode plate.

[0089] The current collector 41 has a sheet shape including short sides and long sides, and the active material layer 42 is formed on at least one surface of the current collector 42, and may include an uncoated portion 43 at the end of the long side in the winding direction X. The uncoated portion 43 is a region where the active material is not coated, that is, a region where the active material layer 42 is not formed. An insulating coating 44 may be further formed at a boundary between the active material layer 42 and the uncoated portion 43. At least a portion of the insulating coating 44 may be formed to overlap with the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating 44 may include a polymer resin and may include an inorganic filler such as Al. 2 O 3 , AlOOH and Al(OH) 3 The insulating coating 44 may be omitted.

[0090] The electrode plate 50 may be manufactured by coating the active material layer 42 onto the current collector 41 to a designed thickness, drying it, and pressing the active material layer 42 to a desired density through a roll pressing process.

[0091] At this time, the active material layer 42 is pattern-coated in a strip shape on the large-area current collector in the longitudinal direction and rolled, and then cut in the longitudinal direction along the uncoated portion between the pattern-coated active material layers 42, and cut into a desired length in the width direction, thereby manufacturing a large number of electrode plates 50 from the large-area current collector at one time. Here, the longitudinal direction of the current collector 41 and the electrode plate 50 is the winding direction X, and when the electrode plate 50 is used to manufacture a jelly roll type electrode assembly, the electrode plate 50 is wound along the winding direction. In addition, when the active material layer 42 is rolled and compressed to a desired density using a roller, the roller moves in this direction.

[0092] The current collector 41 is a current collector for a secondary battery of the present invention, as described above, characterized in that the elongation is 1.5% to 3.0%, the tensile strength is 25 kgf / mm 2 Up to 35kgf / mm 2 The electrode plate 50 may have a width of 60 mm to 110 mm in the direction along the short side of the current collector 41, and a length of 3 m to 5 m in the direction along the long side of the current collector 41. The electrode plate 50 is compressed by performing a rolling process on the active material layer 42 formed on the current collector 41, and the arch length after compression is less than 20 mm. Since the arch length is reduced to less than 20 mm, there is no bending defect during the winding process of the electrode plate 50.

[0093] The smaller the elongation, the easier it is to break. When the elongation of the current collector 41 is less than 1.5%, the rolling processability of the current collector 41 is reduced, and when the electrode plate 50 prepared by coating the active material layer 42 on the current collector is rolled, the current collector 41 may break or crack. Breaking means that the continuity of the material is destroyed and the broken part is physically completely separated. Cracking refers to a state in which the continuity of the material is destroyed only on the surface part and the continuity is maintained in the part below it. On the other hand, when the elongation of the current collector 41 exceeds 3.0%, the elongation of the coated part of the electrode plate 50 (the part forming the active material layer 42) increases, and the curvature is greatly increased.

[0094] If the tensile strength of the current collector 41 is less than 25 kgf / mm 2 Or greater than 35kgf / mm 2 , the electrode processability of the electrode plate 50 cannot be ensured. For example, refer to the following Figures 7 to 11 Describes the cutting processability.

[0095] In order to set the elongation and tensile strength of the current collector 41 to the predetermined range as described above, the manufacturing process of the current collector and / or the material of the current collector 41 may be changed. The elongation may refer to the elongation generated by the pressure applied to the electrode plate when the electrode plate having the active material layer formed on the current collector is rolled using a roller. Since the current collector is generally made of a metal with good ductility and forgeability, the elongation may increase more as the pressure increases during the rolling process. The higher the rolling temperature, the greater the elongation. The greater the hardness value of the rolling roller, the greater the elongation. In addition, the elongation may also depend on the material and thickness of the current collector. In the present invention, the elongation of the current collector 41 of 1.5% to 3.0% generally refers to the elongation after the rolling process is performed within the range of pressure and temperature during the rolling process, the hardness value of the rolling roller, and the material and thickness of the current collector.

[0096] For example, the aluminum foil used as a conventional current collector is prepared by rolling strip aluminum until it becomes a foil with a target thickness, and the elongation can be changed by adjusting the conditions (pressure, temperature) or frequency of the rolling process. As another example, when manufacturing a copper foil used as a conventional current collector, it can be implemented as a method for controlling additional heat treatment temperature and time. As another example, when the copper foil used as a conventional current collector is manufactured by electroplating, the amount of organic additives and / or the amount of specific ions contained in the electroplating solution can be adjusted. For example, if the amount of organic additives is increased, the tensile strength can be improved, and the elongation can be reduced. When the amount of chloride ions is increased, the elongation increases.

[0097] The buckling phenomenon is particularly problematic in the positive electrode current collector which is a conventional aluminum current collector. According to the present invention, by using an aluminum current collector having an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 Up to 35kgf / mm 2The aluminum current collector can suppress the arching phenomenon. It is preferred to form an active material layer containing a lithium transition metal oxide on the current collector and use it as a positive plate. As another example of obtaining elongation and tensile strength within a predetermined range in such an aluminum current collector, the material constituting the current collector is not pure aluminum, but an aluminum alloy, and component changes can be used. That is, although Al is used as the main raw material, the elongation and tensile strength can be changed by adjusting the content of other elements contained therein. For example, the content of Al in the alloy can be 97.5% to 99.5%. When the Al content is within the above range, the elongation decreases and the tensile strength increases compared to pure aluminum. If the Al content is less than 97.5%, it is not desirable because it is worried that the battery performance will be reduced, and when the Al content exceeds 99.5%, the tensile strength will decrease and no anti-arching effect will be produced. Other elements that may be contained in the aluminum alloy are, for example, Si, Fe, Cu, Mg, Mn, Zn, Ni, Sn, Cr, etc. For example, if Si or Mg is added, the elongation may decrease. Adding Cu can improve the tensile strength. In addition, the elongation and tensile strength of the current collector 41 can be adjusted by a person skilled in the art in other specific ways, and the present invention is meaningful in suggesting a particularly preferred range of the elongation and tensile strength.

[0098] The current collector 41 can be cut from a large area current collector substrate. The current collector substrate is used for the manufacture of the electrode plate 50 by processing it into a wound state of a rectangular thin foil with a predetermined width and length. The width of the standard width current collector substrate can be 400mm to 800mm. The width of the wide current collector substrate can be 1000mm to 1800mm. The length of this current collector substrate is several meters to several hundred meters, and it can be processed in a state of being wound on a roll.

[0099] The size of the electrode plate 50 may vary depending on the size of the jelly roll type electrode assembly to be manufactured and the size of the cylindrical battery cell to be manufactured in the end. The size of the electrode plate included in the large cylindrical battery cell with a shape factor of 46800 should be larger than the size of the electrode plate included in the small cylindrical battery cell with a shape factor of 18650 or 21700. The current collector 41 of the embodiment of the present invention is suitable for manufacturing such a large electrode plate.

[0100] Here, the form factor is a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell of an embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 represents that the cell has a circular cross-section.

[0101] In a preferred embodiment, the shape factor of the cylindrical battery cell is 46800, the electrode plate 50 is included in the jelly roll type electrode assembly included in the cylindrical battery cell, the current collector 41 in the electrode plate 50 is an aluminum current collector, and the length of the uncoated portion 43 is 2 mm to 20 mm. The length of the uncoated portion 43 is measured along the width direction of the current collector 41, that is, along the short side direction. The width direction of the current collector 41 is perpendicular to the length direction of the current collector 41. The width of the electrode plate 50 can be 60 mm to 110 mm, and the length can be 3 m to 5 m.

[0102] Since the elongation and tensile strength of the current collector 41 of the present invention are optimally adjusted, expansion does not occur even when the active material layer 42 is pattern-coated and rolled on a large-area current collector. Therefore, it is easy to cut along the uncoated portion between the pattern-coated active material layers 42, and is therefore very suitable for manufacturing a plurality of electrode plates 50.

[0103] The current collector 41 may have a rectangular strip shape, and the uncoated portion 43 may also have a strip shape. In the present invention, the shape of the uncoated portion 43 is also characterized. The uncoated portion 43 includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly, a peripheral uncoated portion B3 adjacent to the periphery of the electrode assembly, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the peripheral uncoated portion B3. In the first embodiment, the height of the uncoated portion 43 is not constant, and there is a relative difference in the winding direction X. That is, the height (length in the Y-axis direction) of the peripheral uncoated portion B3 is relatively smaller than the height of the core-side uncoated portion B1 and the intermediate uncoated portion B2. Since the elongation and tensile strength of the current collector 41 have a predetermined range, when the uncoated portion 43 is cut by setting the height difference as described above, it also has the effect of ensuring appropriate processability. The uncoated portion 43 can be cut by a known metal foil cutting process (such as ultrasonic cutting or stamping). The electrode plate 50 (the height of the uncoated portion 43 is not made constant and has a relative difference in the winding direction X) is very suitable for manufacturing a cylindrical secondary battery, which is designed so that the positive electrode uncoated portion and the negative electrode uncoated portion are located at the top and bottom of the electrode assembly, respectively, and has a structure in which the collecting plate is welded to the uncoated portion to have improved current collection efficiency, that is, a so-called tab-free cylindrical secondary battery.

[0104] The heights of the core-side uncoated portion B1 and the peripheral uncoated portion B3 are equal to or greater than 0 but relatively smaller than the height of the middle uncoated portion B2. In addition, the heights of the core-side uncoated portion B1 and the peripheral uncoated portion B3 may be the same as or different from each other.

[0105] Preferably, the height of the middle uncoated portion B2 may have a stepped shape gradually increasing from the core toward the periphery.

[0106] Patterns 1 to 7 distinguish the middle uncoated portion B2 based on the position of the height change of the uncoated portion 43. Preferably, the number of patterns and the height (length in the Y-axis direction) and width (length in the X-axis direction) of each pattern may be adjusted to dissipate stress as much as possible during the bending process of the uncoated portion 43. Stress dissipation is to prevent tearing of the uncoated portion 43.

[0107] The width dB1 of the core-side uncoated portion B1 is designed by applying a condition that the cavity of the core of the electrode assembly is not covered when the pattern of the middle uncoated portion B2 is bent toward the core.

[0108] In one example, the width dB1 of the core-side uncoated portion B1 may increase in proportion to the bending length of the pattern 1. The bending length corresponds to the height of the pattern with respect to a bending point of the pattern.

[0109] Preferably, the width dB1 of the core-side uncoated portion B1 may be set such that the radial width of the winding turn formed by the core-side uncoated portion B1 is equal to or greater than the bending length of the pattern 1 .

[0110] In a specific example, when the electrode plate 50 is used to manufacture an electrode assembly of a large cylindrical battery having a shape factor (such as 46110, 46800, 48750, 48110, 48800), the width dB1 of the core-side uncoated portion B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly.

[0111] In one embodiment, the width of each pattern may be designed to constitute the same winding turn of the electrode assembly.

[0112] In one variation, the height of the middle uncoated portion B2 may have a stepped shape, first increasing and then decreasing from the core toward the periphery.

[0113] In another variation, the height of the outer circumferential uncoated portion B3 may gradually decrease toward the outer circumference.

[0114] In another variation, the pattern structure applied to the middle uncoated portion B2 may extend to the peripheral uncoated portion B3 (see dotted line).

[0115] On the other hand, since the elongation and tensile strength of the current collector 41 are set within a predetermined range, even if the load density of the active material layer 42 is sufficient, the arch length after rolling is reduced. Therefore, in the present invention, the energy density per unit area of ​​the active material layer 42 can be increased to 1 mAh / cm 2 Up to 6mAh / cm 2. When the energy density of the active material layer 42 satisfies the above range, it can be applied to medium or large capacity battery cells, and the load per electrode weight is reduced, so that the thickness of the electrode can be reduced. The thickness of the active material layer 42 can be 15μm to 200μm. As the thickness of the current collector 41 increases, the tensile strength decreases, and the elongation increases instead, so the thickness of the current collector 41 can also have an appropriate range so that the elongation and tensile strength are set within a predetermined range. For example, the thickness of the current collector 41 can be 3μm to 500μm, and it is not suitable for winding if it is too thick. For example, its thickness can be 7μm to 20μm. The bonding strength with the active material can be enhanced by forming fine concave and convex objects on the surface of the current collector 41. For example, the current collector 41 can have various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven body, and the like.

[0116] Figure 7 It is a plan view showing the structure of an electrode plate according to a second embodiment of the present invention.

[0117] Figure 7 The electrode plate 60 and Figure 6 The difference between the electrode plate 50 and the electrode plate 60 is only the shape of the uncoated portion 43, and the rest of the structure is basically the same. The electrode plate 60 is more suitable for manufacturing a tab-free cylindrical secondary battery.

[0118] like Figure 7 As shown, the uncoated portion 43 can be divided into a plurality of segments 61 by a cutting process. The segments 61 can be cut with a laser. That is, the uncoated portion 43 can have a cut in the direction along the short side of the current collector 41. In addition, the segments 61 can be formed by a known metal foil cutting process, such as ultrasonic cutting or stamping. In the present invention, since the elongation and tensile strength of the current collector 41 are designed, when the segments 61 have a cut, the occurrence of fractures or cracks in the cut region, i.e., the uncoated portion 43 in the cut region, can be minimized. Preferably, according to the present invention, there is no fracture or crack in the uncoated portion 43 in the cut region in the electrode plate 60.

[0119] The heights of the core-side uncoated portion B1 and the peripheral uncoated portion B3 may be relatively smaller than the height of the middle uncoated portion B2. In addition, the heights of the core-side uncoated portion B1 and the peripheral uncoated portion B3 may be the same or different.

[0120] Preferably, at least a portion of the middle uncoated portion B2 may include a plurality of segments 61. The heights of the plurality of segments 61 may gradually increase from the core toward the periphery.

[0121] After winding, the plurality of segments 61 may be bent in the radial direction of the electrode assembly, for example, toward the core and overlapped into several sheets. By welding the current collector to the bent and overlapping segments 61 in this manner, a battery cell with improved current collection efficiency may be manufactured. By setting the elongation and tensile strength of the current collector 41 within a predetermined range, when the segment 61 is bent, an effect is produced in which the segment 61 is smoothly bent without tearing or damage, stress concentration, or fracture of the corresponding area.

[0122] In one aspect, the segment 61 may have a shape in which the width of the upper portion is smaller than that of the lower portion. The segment 61 may have a rectangular, trapezoidal, triangular, parallelogram, semicircular or semi-elliptical structure. In another aspect, at least one side forming the periphery of the segment may be transformed into a curved shape, and the shape of the vertex may also be transformed into a circle. In another aspect, the segment may have a shape in which the width of the lower portion is larger than that of the upper portion, and the width decreases stepwise and / or gradually from the lower portion to the upper portion.

[0123] In order to prevent the active material layer 42 and / or the insulating coating 44 from being damaged during the bending of the uncoated portion 43, it is preferred to provide a predetermined gap ( Figure 8 C4). This is because when the uncoated portion 43 is bent, stress is concentrated near the bottom of the cutting groove. The gap is preferably 0.2 mm to 4 mm. When the gap is adjusted within the corresponding numerical range, the stress generated during the bending of the uncoated portion 43 can be prevented from damaging the active material layer 42 and / or the insulating coating 44 near the bottom of the cutting groove. In addition, the gap prevents damage to the active material layer 42 and / or the insulating coating 44 due to tolerances during the incision or cutting of the interval 61. Preferably, when the electrode plate 60 is wound into the electrode assembly, at least a portion of the insulating coating 44 can be exposed to the outside of the diaphragm. In this case, when the segment 61 is bent, the insulating coating 44 can support the bending point.

[0124] The plurality of segments 61 may form a plurality of segment groups from the core toward the periphery. The width, height and spacing of the segments belonging to the same segment group may be substantially the same.

[0125] Figure 8 It is shown Figure 7 FIG. 6 is a diagram defining the width, height and spacing of the segments 61 in the electrode plate 60 .

[0126] refer to Figure 8, the length C1, height C2 and spacing C3 of the section 61 are designed to prevent abnormal deformation of the uncoated portion 43 while sufficiently increasing the number of overlapping layers of the uncoated portion to prevent the uncoated portion 43 from tearing during the bending process of the uncoated portion 43 and improve the welding strength. Abnormal deformation means that the uncoated portion below the bending point does not maintain a straight state and deforms irregularly when sitting down. The number of overlapping layers may preferably be 10 or more.

[0127] The segment 61 is bent above a point C4 passing through the lower end of the cutting groove 62. The cutting groove 62 enables the segment 61 to be bent smoothly and easily in the radial direction of the electrode assembly.

[0128] The width C1 of the segment 61 is defined as the length between two points where two straight lines extending from the two sides 62b of the segment 61 and a straight line extending from the bottom 62a of the cutting groove 62 intersect. The height C2 of the segment 61 is defined as the shortest distance between the uppermost side of the segment 61 and a straight line extending from the bottom 62a of the cutting groove 62. The pitch C3 of the segment 61 is defined as the length between two points where a straight line extending from the bottom 62a of the cutting groove 62 and a straight line extending from the two sides 62b connected to the bottom 62a intersect. When the side 62b and / or the bottom 62a are curved, the straight line may be replaced by a tangent line extending from the side 62b or the bottom 62a at the intersection where the side 62b intersects with the bottom 62a.

[0129] It is preferred that the width C1 of the segment 61 is adjustable within a range of 1 mm to 6 mm. If C1 is less than 1 mm, there is a region or empty space (gap) where the segments 61 do not overlap each other sufficiently to ensure sufficient welding strength when bent toward the core. On the other hand, if C1 exceeds 6 mm, there is a possibility that the uncoated portion 43 near the bending point is stress-torn when the segment 61 is bent.

[0130] In addition, the height of the segment 61 can be adjusted within the length range of the uncoated portion 43. For example, the length of the uncoated portion 43 is 2 mm to 20 mm. Preferably, the height of the segment 61 can be adjusted within the range of 2 mm to 20 mm or within the range of 2 mm to 10 mm. If C2 is less than 2 mm, an area or blank space (gap) will be generated in which the overlap between the segments 61 is not sufficient to fully ensure the welding strength when bending toward the core. Since the elongation and tensile strength of the current collector 41 are optimized, it can be said that C2 is less restricted than when a conventional current collector is used. In a conventional current collector, the uncoated portion must be extended to increase C2, and when the uncoated portion is extended, it is difficult to manufacture the electrode plate while keeping the uncoated portion uniformly flat in the winding direction X. That is, when the height of the uncoated portion increases, expansion occurs. However, in the present invention, since a current collector 41 with optimal elongation and tensile strength is used, the range of C2 can be increased while suppressing expansion. The larger C2 is, the easier the subsequent bending process is, and the larger the overlapping area and welding area are, so that the welding strength can be ensured.

[0131] In addition, the interval C3 of the segments 61 can be adjusted within a range of 0.05 mm to 1 mm. If C3 is less than 0.05 mm, the uncoated portion 43 near the bending point C4 may be torn by stress when the segment 61 is bent. On the other hand, when C3 exceeds 1 mm, an area or empty space (gap) is generated where the segments 61 do not overlap each other enough to fully ensure the welding strength when the segment 61 is bent.

[0132] Since the current collector 41 having optimized elongation and tensile strength is used, if the interval C3 of the segment 61 is adjusted within the range of 0.05 mm to 1 mm, the segment 61 can be formed without cracking or breaking. When the electrode plate 60 is wound in the process after the segment 61 is formed, even if the segment 61 is not cracked during formation, cracking may occur due to operating tension. In the current collector 41 having an elongation and tensile strength within the range suggested by the present invention, it is confirmed by experiments that if the interval C3 of the segment 61 is 0.5 mm or more, cracking caused by operating tension is prevented, as described later with reference to Fig. 9 described.

[0133] The cutting groove 62 is inserted between two adjacent sections 61 in the winding direction X. The cutting groove 62 corresponds to the space generated when the uncoated portion 43 is removed. Preferably, the edge portions of the two lower ends of the cutting groove 62 have a rounded shape. That is, the cutting groove 62 includes a substantially flat bottom 62a and a circular portion 62c. The circular portion 62c connects the bottom 62a and the side 62b of the section 61. In a modified example, the bottom 62a of the cutting groove 62 can be replaced with an arc. In this case, the side 62b of the section 61 can be smoothly connected by the arc of the bottom 62a.

[0134] The radius of curvature of the circular portion 62c may be greater than 0 and less than or equal to 0.5 mm, preferably greater than 0 and less than or equal to 0.1 mm, and more preferably 0.01 mm to 0.05 mm. When the radius of curvature of the circular portion 62c satisfies the above numerical range, cracking can be prevented from occurring at the lower portion of the cutting groove 62 when the electrode plate 60 is running in a winding process or the like, which will be referred to later. Fig. 9 It has been verified by experiments.

[0135] Fig. 9 This is a photo of the test results, which confirmed whether cracking caused by operating tension occurred depending on the spacing and shape of the segments.

[0136] Fig. 9 (a) and (b) show that the interval C3 of the segments is 0.1 mm and 0.3 mm, respectively, and cracking occurs due to the operating tension (the cracking site is indicated by a dotted circle). In addition, (a) and (b) show that the bottom 62a of the cutting groove 62 has an arc shape, and it is confirmed that the maximum stress of 14.4 MPa and 10.9 MPa is generated at the center of the bottom 62a, respectively. Cracks occur in the area where the maximum stress occurs.

[0137] Fig. 9 (c), (d) and (e) show that the interval C3 of the segments is 0.5 mm, 0.7 mm and 0.9 mm, respectively, and no cracking due to operating tension occurs. In particular, (c), (d) and (e) show the case where the cutting groove 62 includes a substantially flat bottom 62a and a circular portion 62c, where it is confirmed that a maximum stress of 10.3 MPa is generated at the bottom 62a in (c), and maximum stresses of 9.5 MPa and 8.5 MPa are generated in the circular portion 62a in (d) and (e), respectively. Compared with (a) and (b), this maximum stress is not only smaller, but also does not cause cracking. Therefore, it can be seen that the interval C3 of the segments is preferably 0.5 mm or more.

[0138] In particular, in (d) and (e), the spacing C3 is greater than 0.5 mm, so that the distinction between the bottom 62a and the circular portion 62c becomes clearer, and the maximum stress is not concentrated on the bottom 62a, but diffused to the circular portion 62c, so that the bottom 62a acts as a stress relief area, so it can be confirmed that it is more excellent in preventing the occurrence of cracks. In addition, in (d) and (e), the radius of curvature of the circular portion 62c is 0.02 mm, which means that the maximum stress of 14.4 MPa in the same state as (a) can be reduced to 9.5 MPa and 8.5 MPa, respectively, so it can be seen that this is very preferable from the perspective of preventing the occurrence of cracks.

[0139] Refer to Figure 7 , the width dB1 of the core-side uncoated portion B1 is designed by applying the condition that the segment 61 of the middle uncoated portion B2 does not cover the cavity of the core of the electrode assembly when bending toward the core. The cavity of the core is formed where the winding core used in the winding process of the electrode assembly is removed, and the cavity is used as a channel for injecting electrolyte. However, when the corresponding channel is closed, it is difficult to inject electrolyte. Therefore, the width dB1 of the core-side uncoated portion B1 can be determined so that the core-side uncoated portion B1 adjacent to the core of the electrode assembly is bent and does not completely or significantly close the cavity in the core of the electrode assembly.

[0140] In one example, the width dB1 of the core-side uncoated portion B1 may increase in proportion to the bending length of the segment 61 of group 1. The bending length corresponds to the height of the segment 61 relative to the bending point 63 ( Figure 8 ). refer to Figure 8 , C4 represents the lowest bending point. The bending point can be appropriately set at the top of C4. Regarding the bending point, C4 is the lowest point where bending can be performed, and the bending point can be moved upward relative to that shown. The bending length is the length from the lowest point of the bent portion to the top of the segment 61. Specifically, the bending point can be set at a predetermined point at the height C2 of the segment 61 relative to C4. The predetermined point can be set to prevent the stress generated during the bending of the segment 61 from causing physical damage to the active material layer 42 or the insulating coating 44, and to fully ensure the number of overlapping layers in the radial direction when the segment 61 is bent in the opposite direction to the electrode assembly, thereby achieving sufficient welding strength when the current collecting plate is welded to the bent area of ​​the segment 61.

[0141] Preferably, based on the height C2 of the section 61, the predetermined point may be set to a height of at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or at least 80%.

[0142] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly of a large cylindrical battery cell having a shape factor such as 46110, 46800, 48750, 48110, 48800, etc., the width dB1 of the core-side uncoated portion B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly.

[0143] According to the present invention as described above, by improving the structure of the uncoated portion 43 adjacent to the electrode assembly core to prevent the cavity in the electrode assembly core from being closed when the uncoated portion 43 is bent, the electrolyte injection process and the welding process of the battery case and the current collecting plate can be easily performed.

[0144] In one embodiment, the width of each segment group may be designed to constitute the same winding turns of the electrode assembly.

[0145] Here, when the electrode plate 60 is in a wound state, the winding turns may be calculated based on the end of the core-side uncoated portion B1.

[0146] In another variation, the width of each segment group may be designed to constitute at least one winding turn of the electrode assembly.

[0147] In another variant, the width and / or height and / or spacing of the segments 61 belonging to the same segment group may increase or decrease gradually and / or stepwise and / or irregularly within the group.

[0148] exist Figure 7 In the example shown, groups 1 to 8 are only examples of segment groups. The number of groups and the number of segments 61 included in each group may be adjusted so that the segments 61 overlap in several layers to maximize stress distribution during bending of the uncoated portion 43 and sufficiently achieve welding strength.

[0149] In another variant, the height of the peripheral uncoated portion B3 can be gradually or step-wise reduced. In addition, the segment structure of the middle uncoated portion B2 can also be extended to the peripheral uncoated portion B3 (reference dotted line). In this case, the peripheral uncoated portion B3 can also include multiple sections similar to the middle uncoated portion B2. In this case, the width and / or height and / or spacing of the segment of the peripheral uncoated portion B3 can be greater than the middle uncoated portion B2.

[0150] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly of a large cylindrical battery cell having a form factor such as 46110, 46800, 48750, 48110, 48800, etc., the segment may form eight groups. Preferably, the width dB1 of the core-side uncoated portion B1 may be 180 mm to 350 mm. The width of group 1 may be 35% to 40% of the thickness of the core-side uncoated portion B1. The width of group 2 may be 130% to 150% of the width of group 1. The width of group 3 may be 120% to 135% of the width of group 2. The width of group 4 may be 85% to 90% of the width of group 3. The width of group 5 may be 120% to 130% of the width of group 4. The width of group 6 may be 100% to 120% of the width of group 5. The width of group 7 may be 90% to 120% of the width of group 6. The width of group 8 may be 115% to 130% of the width of group 7 .

[0151] The reason why the widths of groups 1 to 8 do not show a constant increasing or decreasing pattern is that the width of the segments gradually increases from group 1 to group 8, but the number of segments included in a group is limited to an integer. Therefore, the number of segments can be reduced in a specific segment group. Therefore, the width of the group may show an irregular changing pattern from the core to the periphery, as shown in the above example.

[0152] The segment structure of the middle uncoated portion B2 is also applicable to the core-side uncoated portion B1. However, if the segment structure is applied to the core-side uncoated portion B1, when the segment 61 of the middle uncoated portion B2 is bent according to the curvature radius of the core, the end of the core-side uncoated portion B1 may be bent toward the periphery, which is so-called reverse forming. Therefore, it is preferred that the core-side uncoated portion B1 does not have a segment structure.

[0153] Since the elongation and tensile strength of the current collector 41 have a predetermined range, when the uncoated portion 43 is segmented as described above, the present invention has the effect of ensuring very suitable workability, such as cut workability. Since there is no break or crack in the cut area, the structural robustness of the electrode plate 60 and the electrode assembly including the electrode plate is ensured, and no unnecessary electrical contact or current path is generated.

[0154] Such an electrode plate 60 is very suitable for manufacturing a non-tab cylindrical secondary battery. Therefore, the current collector 41 of the present invention and the electrode plate 60 including the current collector 41 are very suitable for manufacturing large batteries, such as cylindrical battery cells with a shape factor of 46110, 48750, 48110, 48800, 46800, etc.

[0155] Fig.10 It is a plan view showing the structure of an electrode plate according to a third embodiment of the present invention.

[0156] refer to Fig.10 , Fig.10 The electrode plate 70 has Figure 7 The electrode plate 60 has a substantially similar structure to that of the electrode plate 60, except that the shape of the segment 61' is Figure 7 The electrode plate 60 is changed from a rectangular shape to a trapezoidal shape.

[0157] Fig.11 It is shown Fig.10 FIG. 5 is a diagram defining the width, height and spacing of the segments 61 ′ in the electrode plate.

[0158] refer to Fig.11 , refer to Figure 8 The description of the width C1, height C2 and spacing C3 of the segment 61 described can be directly applied to the width D1, height D2 and spacing D3 of the segment 61'. In addition, the width of the top of the segment 61' can be 0.5mm to 6mm. The segment 61' is bent at or above the point D4 passing through the bottom of the cutting groove 62.

[0159] In the plurality of segments 61', the lower inner angle θ of the trapezoid may increase from the core to the periphery. As the radius of the electrode assembly increases, the curvature increases. If the lower inner angle θ of the segment 61' increases as the radius of the electrode assembly increases, the stress generated in the radial and circumferential directions may be released when the segment 61' is bent. In addition, if the lower inner angle θ increases, when the segment 61' is bent, the area overlapped with the inner segment 61' and the number of overlapping layers also increase, thereby ensuring uniform welding strength in the radial and circumferential directions and forming a flat curved surface.

[0160] In one example, if the electrode plate 70 is used to manufacture an electrode assembly of a cylindrical battery cell having a shape factor of 46110, 48750, 48110, 48800, 46800, etc., when the radius of the electrode assembly increases from 4 mm to 22 mm, the inner angle of the segment 61' can be increased in a step-wise manner within a range of 60 to 85 degrees. When the uncoated portion 43 is deformed to have a segment 61' as described above, since the elongation and tensile strength of the current collector 41 have a predetermined range, the present invention has the effect of ensuring very suitable processability, i.e., cut processability. There is no breakage or cracking in the cut area.

[0161] The experimental results below show the results of measuring the buckling length and notch processability as a function of the elongation and tensile strength of the aluminum current collector.

[0162] After coating the active material layer on the aluminum current collector, the uncoated portion of the aluminum current collector may be Figure 7 and 10The incision is made along the longitudinal direction of the uncoated part to be divided into a plurality of sections. The incision processability can be judged by whether a break (cracking) occurs in the incision area. If a break occurs, it is shown as unqualified in Table 1, and if no break occurs, it is shown as qualified.

[0163] For elongation, after the current collector sample is connected to the sample clamping part of a universal testing device (e.g., Instron 3345, 3365UTM), the tensile strain is measured when pulled at a constant speed, and the tensile strain when the sample breaks can be measured as elongation. The tensile strength can also be measured using the universal testing device according to the measurement method of IPC-TM-650. In addition, the elongation can be obtained from the deformation when the sample breaks in the tensile strength test based on IPC-TM-650 at room temperature. The tensile strength test specifications in IPC-TM-650 are shown in 2.4.18, 2.4.19, etc. For example, it can be measured by IPC-TM-650 (2.4.19) method.

[0164] Specifically, the current collector sample size is 12.7 mm wide and 150 mm long, and the measuring speed is 20 mm / min. Since this is a measurement method in which stretching occurs in the center part of the sample, a 50 mm gauge is marked in the center part of the sample (for example, a line with a length of 50 mm parallel to the longitudinal direction of the sample is marked in the center part of the sample), and UTM is used as an apparatus. After the prepared current collector sample is installed in the UTM, the test is carried out at a reference speed (20 mm / min), and the tensile strength value is obtained by dividing the magnitude of the force when the center part of the sample is broken by the cross-sectional area of ​​the sample (sample width x sample thickness). Then, the broken samples are arranged in the longitudinal direction, and the elongation is calculated using Equation 1 by the elongation of the 50 mm gauge marked from the beginning.

[0165] [Table 1]

[0166]

[0167] Referring to the experimental results, when an aluminum current collector having an elongation of more than 3.0% is used to manufacture the electrode plate (Comparative Examples 1, 3 and 4), the arch length is measured to be about 20 mm or more. On the other hand, when an aluminum current collector having an elongation of 1.5% to 3.0% is used to manufacture the electrode plate (Examples 1 and 2), the arch length is measured to be 16 mm and 11 mm, respectively. When the measured arch length exceeds 20 mm, bending defects and fractures occur. On the other hand, in Comparative Example 2, although the elongation does not exceed 3.0%, fractures occur in the cut area, so the cut processability is poor. This is because the tensile strength is less than 25 kgf / mm 2Such problems do not occur in the case of Examples 1 and 2. Therefore, according to the present invention, by designing the elongation and tensile strength of the current collector, not only the generation of the camber can be minimized, but also the occurrence of the fracture during the segment cutting can be minimized.

[0168] Fig.12 This is a photograph comparing the expansion degree when the current collector of Comparative Example 3 and the current collector of Example 1 are used to manufacture an electrode plate. Fig.12 The photograph shown in (a) is an electrode plate (positive electrode plate) manufactured using the current collector of Comparative Example 3. Fig.12 The photograph shown in (b) is an electrode plate (positive electrode plate) manufactured using the current collector of Example 1.

[0169] refer to Fig.12 , it can be visually confirmed that less expansion occurs in the electrode plate manufactured from the current collector of Example 1.

[0170] The structure of the electrode plates 40, 60, 70 of the above-mentioned embodiment (variant) may be applied to at least one of the first electrode plate and the second electrode plate having different polarities included in the jelly roll type electrode assembly. In addition, when the electrode structure of the embodiment (variant) is applied to any one of the first electrode plate and the second electrode plate, a conventional electrode plate structure may be applied to the other. In addition, the electrode plate structures applied to the first electrode plate and the second electrode plate may be different from each other instead of being the same.

[0171] For example, when the first electrode plate and the second electrode plate are respectively a positive electrode plate and a negative electrode plate, any of the above-mentioned embodiments (variations) may be applied to the first electrode plate, the conventional electrode plate structure (see Figure 1 ) can be applied to the second electrode plate.

[0172] As another example, when the first electrode plate and the second electrode plate are respectively a positive electrode plate and a negative electrode plate, any of the above embodiments (variants) may be selectively applied to the first electrode plate, and any of the above embodiments (variants) may be selectively applied to the second electrode plate.

[0173] In the present invention, the positive electrode active material and the negative electrode active material coated on the current collector may be any type of active material as long as the active material is well known in the art.

[0174] In one example, the positive electrode active material may include a x M y ]O 2+zAn alkali metal compound represented by (A includes at least one of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, 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; the stoichiometric coefficients x, y, and z are selected to keep the compound electrically neutral).

[0175] Preferably, the positive electrode active material contains a lithium transition metal oxide. The lithium transition metal may include a nickel-cobalt-manganese-based lithium oxide, and may include a high-concentration nickel-cobalt-manganese-based lithium oxide with a high nickel content.

[0176] In another embodiment, the positive electrode active material may be an alkali metal compound xLiM 1 O 2 (1 - x)Li 2 M 2 O 3 (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), as disclosed in US 6,677,082, US 6,680,143, etc.

[0177] In another example, the positive electrode active material may be a lithium metal phosphate represented by the chemical general formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M 1 includes at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 includes at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 includes a halogen element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, and z are selected to keep the compound electrically neutral), or Li 3 M 2 (PO 4 ) 3 (M includes at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al).

[0178] Preferably, the positive electrode active material may include primary particles and / or secondary particles formed by aggregation of primary particles.

[0179] In one example, the negative electrode active material may use carbon materials, lithium metal or lithium metal compounds, silicon or silicon compounds, tin or tin compounds, etc. Metal oxides with a potential less than 2V, such as TiO 2 or SnO 2 It can also be used as a negative electrode active material. As the carbon material, low-crystalline carbon and high-crystalline carbon can be used.

[0180] The separator may include a porous polymer film of a single or laminated structure, for example, made of a polyolefin-based polymer, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer. In another example, the separator may be a common porous nonwoven, for example, a nonwoven made of glass fiber or polyethylene terephthalate fiber having a high melting point.

[0181] At least one surface of the separator may include a coating of inorganic particles. Otherwise, the separator itself may be made of a coating of inorganic particles. The inorganic particles contained in the coating may be connected with a binder so that there is a gap volume between adjacent inorganic particles.

[0182] The inorganic particles may include an inorganic material having a dielectric constant of 5 or more. In a non-limiting example, the inorganic particles may include an inorganic material selected from the group consisting of Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT), Pb(Mg 1 / 3 Nb 2 / 3 ) 3 -PbTiO 3 (PMN-PT), BaTiO 3 、HfO 2 )、SrTiO 3 、TiO 2 、Al 2 O 3 、ZrO 2 SnO 2 、CeO 2 , MgO, CaO, ZnO and Y 2 O 3 At least one material of the group consisting of.

[0183] Fig.13 is a cross-sectional view of an electrode assembly according to an embodiment of the present invention. Fig.13 is a cross-sectional view taken along the Y-axis direction (winding axis direction) of the jelly-roll type electrode assembly, wherein Figure 6 The electrode plate 50 of the first embodiment shown in FIG. 1 is applied to a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate).

[0184] The electrode assembly 80 can be referred to Figure 2 The present invention is manufactured by the winding method described. It has a structure in which the first and second electrode plates in the shape of sheets and the separator inserted therebetween are wound in one direction. For the convenience of description, the protruding structure of the uncoated portions 43a, 43b extending to the outside of the separator is shown in detail, and the illustration of the winding structure of the first electrode plate, the second electrode plate and the separator is omitted. The uncoated portion 43a protruding upward extends from the first electrode plate, and the uncoated portion 43b protruding downward extends from the second electrode plate. At least a portion of the upper uncoated portion 43a and the lower uncoated portion 42b are exposed to the outside of the separator, and they themselves serve as electrode tabs.

[0185] refer to Fig.13 The uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 80, a peripheral uncoated portion B3 adjacent to the peripheral surface of the electrode assembly 80, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the peripheral uncoated portion B3.

[0186] The height of the peripheral uncoated portion B3 (the length in the Y-axis direction) is relatively smaller than the height of the middle uncoated portion B2. Therefore, when the peripheral uncoated portion B3 is compressed in the curling portion of the battery shell, the occurrence of an internal short circuit can be prevented. As described above, according to the present invention, the internal short circuit inside the cylindrical battery cell caused by partial deformation of the electrode assembly 80 can be prevented by improving the structure of the uncoated portions 43a, 43b, so that the electrode assembly 80 and the inner peripheral surface of the battery are not disturbed during the formation of the curling portion of the battery shell.

[0187] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode plate structure of other embodiments (variations).

[0188] Ends 81 of the upper and lower uncoated portions 43a and 43b may be bent in a radial direction of the electrode assembly 80, for example, from the outer circumference toward the core. At this time, the outer peripheral uncoated portion B3 may not be substantially bent.

[0189] Fig.14It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of the jelly-roll type electrode assembly 100, in which any of the electrode plates 60, 70 of the second to third embodiments is applied to the first electrode plate (positive electrode plate) and the second electrode plate (negative electrode plate).

[0190] refer to Fig.14 The uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 100, a peripheral uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the peripheral uncoated portion B3.

[0191] The figure schematically shows a pattern of height variation of the uncoated portions 43a, 43b. That is, the height of the uncoated portions 43a, 43b may change irregularly depending on the location of the cut section. For example, when the side of the trapezoidal segments 61, 61' is cut, the height of the uncoated portion in the cross section is lower than the height of the segments 61, 61'. Therefore, it should be understood that the height of the uncoated portions 43a, 43b shown in the figure showing the cross section of the electrode assembly corresponds to the uncoated portion ( Figure 8 C2 and Fig.11 The average value of the height of D2).

[0192] The height of the core-side uncoated portion B1 is relatively smaller than the height of the middle uncoated portion B2. In addition, in the middle uncoated portion B2, the bending length of the innermost uncoated portion 43a is equal to or smaller than the radial length R of the core-side uncoated portion B1. The bending length H corresponds to the height of the uncoated portion 43a based on the point where the uncoated portion 43a is bent ( Figure 8 h and Fig.11 D4 is the lowest point of the bending point, and the bending point can be set above D4.

[0193] Therefore, even if the middle uncoated portion B2 is bent, the bent portion does not close the cavity 102 of the core of the electrode assembly 100. If the cavity 102 is not closed, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. In addition, by inserting the welding jig into the cavity 102, the welding process between the negative electrode current collector and the battery case can be easily performed.

[0194] The height of the peripheral uncoated portion B3 is relatively smaller than that of the middle uncoated portion B2. Therefore, when the peripheral uncoated portion B3 is compressed at the curling portion of the battery case, the occurrence of an internal short circuit can be prevented.

[0195] In one variation, with Fig.14 Different from the above, the height of the peripheral uncoated portion B3 can be gradually or step-wise reduced. Fig.14 In the embodiment, the height of the middle uncoated portion B2 is the same as that of a portion of the periphery, but the height of the middle uncoated portion B2 can be gradually or step-wise increased from the boundary between the core-side uncoated portion B1 and the middle uncoated portion B2 to the edge between the middle uncoated portion B2 and the peripheral uncoated portion B3.

[0196] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode plate structure of other embodiments (variations).

[0197] Ends 101 of the upper and lower uncoated portions 43a and 43b may be bent in a radial direction of the electrode assembly 100, for example, from the periphery toward the core. At this time, the core-side uncoated portion B1 and the peripheral uncoated portion B3 are substantially not bent.

[0198] When the middle uncoated portion B2 includes a plurality of segments, the bending stress is released to prevent the uncoated portion 43a near the bending point from being torn or abnormally deformed. In addition, when the width and / or height and / or spacing of the segments are adjusted according to the numerical range of the above-mentioned embodiment, the segments overlap into several layers, bend toward the core while fully achieving the welding strength, and no blank space (gap) is formed in the bending surface (surface observed from the Y axis). In addition, since the elongation and tensile strength of the collector 41 are optimized, no breakage or cracking occurs between the plurality of segments.

[0199] Fig.15 It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of an electrode assembly 110 according to another embodiment of the present invention.

[0200] Fig.15 The electrode assembly 110 and Fig.14 The electrode assembly 100 has substantially the same structure except that a height of the peripheral uncoated portion B3 is substantially the same as a height of the outermost side of the middle uncoated portion B2.

[0201] The peripheral uncoated portion B3 may include a plurality of segments. With regard to the configuration related to the plurality of segments, the description of the above-mentioned embodiment (variation) can be applied in substantially the same manner.

[0202] In the electrode assembly 110, the height of the core-side uncoated portion B1 is relatively smaller than that of the middle uncoated portion B2. In addition, in the middle uncoated portion B2, the bending length H of the innermost uncoated portion is equal to or smaller than the radial length of the core-side uncoated portion B1.

[0203] Therefore, even if the middle uncoated portion B2 is bent, the bent portion does not close the cavity 112 of the core of the electrode assembly 110. If the cavity 112 is not closed, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. In addition, by inserting the welding jig into the cavity 112, the welding process between the negative electrode current collector and the battery case can be easily performed.

[0204] In one variation, the structure in which the height of the middle uncoated portion B2 gradually or stepwise increases from the core to the periphery may extend to the peripheral uncoated portion B3. In this case, the height of the uncoated portion 43a may gradually or stepwise increase from the boundary between the core-side uncoated portion B1 and the middle uncoated portion B2 to the outermost surface of the electrode assembly 110.

[0205] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode plate structure of other embodiments (variations).

[0206] Ends 111 of the upper and lower uncoated portions 43a and 43b may be bent toward the core from the outer circumference of the electrode assembly 110. At this time, the core-side uncoated portion B1 is substantially not bent.

[0207] When the middle uncoated portion B2 and the peripheral uncoated portion B3 include multiple sections, the bending stress is released to prevent the uncoated portions 43a, 43b near the bending point from being torn or abnormally deformed. In addition, when the width and / or height and / or spacing of the sections are adjusted according to the numerical range of the above-mentioned embodiment, the sections overlap into several layers to fully achieve the welding strength while bending toward the core, and no blank space (gap) is formed in the bending surface (surface observed from the Y axis). In addition, since the elongation and tensile strength of the collector 41 are optimized, no breakage or cracking occurs between the multiple sections.

[0208] Various electrode assembly structures according to embodiments of the present invention may be applied to jelly-roll type cylindrical battery cells.

[0209] Preferably, the cylindrical battery cell may be, for example, a cylindrical battery cell having a shape factor ratio (defined as a value obtained by dividing the diameter of the cylindrical battery cell by the height, ie, a ratio of the height H to the diameter Φ) greater than about 0.4.

[0210] When an electrode assembly having a non-electrode ear structure is applied to a cylindrical battery cell having a shape factor ratio greater than 0.4, the stress applied in the radial direction when the uncoated portion is bent is large, so the uncoated portion may be easily torn. In addition, when the current collector is welded to the curved surface of the uncoated portion, the number of overlapping layers of the uncoated portion should be sufficiently increased to fully achieve welding strength and reduce resistance. This requirement can be achieved by the electrode plate and electrode assembly of the embodiment (variant) of the present invention.

[0211] The battery cell of the embodiment of the present invention may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of about 46 mm, a height of about 110 mm, and an aspect ratio of 0.418.

[0212] A battery cell according to another embodiment of the present invention may be a cylindrical battery cell having a generally cylindrical shape with a diameter of about 48 mm, a height of about 75 mm, and an aspect ratio of 0.640.

[0213] A battery cell according to another embodiment of the present invention may be a cylindrical battery cell having a generally cylindrical shape with a diameter of about 48 mm, a height of about 110 mm, and an aspect ratio of 0.418.

[0214] A battery cell according to another embodiment of the present invention may be a cylindrical battery cell having a generally cylindrical shape with a diameter of about 48 mm, a height of about 80 mm, and an aspect ratio of 0.600.

[0215] A battery cell according to another embodiment of the present invention may be a cylindrical battery cell having a generally cylindrical shape with a diameter of about 46 mm, a height of about 80 mm, and an aspect ratio of 0.575.

[0216] Generally, battery cells having a shape factor ratio of about 0.4 or less are used. That is, for example, 18650 cells, 21700 cells, etc. are generally used. The diameter of the 18650 battery is about 18 mm, the height is about 65 mm, and the shape factor ratio is 0.277. The diameter of the 21700 battery is about 21 mm, the height is about 70 mm, and the shape factor ratio is 0.300.

[0217] Hereinafter, a cylindrical battery cell according to an embodiment of the present invention will be described in detail.

[0218] Fig.16 is a cross-sectional view taken along the Y-axis direction, showing a cylindrical battery cell 170 according to an embodiment of the present invention.

[0219] refer to Fig.16, the cylindrical battery cell 170 of the embodiment of the present invention includes an electrode assembly 141 having a first electrode plate, a separator, and a second electrode plate. The cylindrical battery cell 170 includes a battery case 171 through which a rivet terminal 172 is mounted. The battery case 171 is made of a metal material having conductivity such as aluminum or steel. The battery case 171 accommodates the electrode assembly 141 in an internal space and also accommodates an electrolyte together.

[0220] The electrolyte may be a + B - Here, A + Including alkali metal cations such as Li + 、Na + or K + or a combination thereof. In addition, B - Including the selection of F - , Cl - Br - ,I - 、NO 3 - 、N(CN) 2 - , BF 4 - , ClO 4 - 、AlO 4 - 、AlCl 4 - PF 6 - , SbF 6 - , AsF 6 - , BF 2 C 2 O 4 - , B.C. 4 O 8 - ,(CF 3 ) 2 PF 4 - ,(CF 3 ) 3 PF 3 - ,(CF 3 ) 4 PF 2 - ,(CF 3 ) 5 PF - ,(CF 3 ) 6 P- CF 3 SO 3 - , C 4 F 9 SO 3 - CF 3 CF 2 SO 3 - ,(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - CF 3 CF 2 (CF 3 ) 2 CO - ,(CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - ,(CF 3 SO 2 ) 3 C - CF 3 (CF 2 ) 7 SO 3 - CF 3 CO 2 - , CH 3 CO 2 - 、SCN - and (CF 3 CF 2 SO 2 ) 2 N - At least one anion of the group consisting of.

[0221] The electrolyte may also be dissolved in an organic solvent. The organic solvent may include 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.

[0222] The electrode assembly 141 may have a jelly roll shape. The electrode assembly 141 may be manufactured by winding a stack formed by sequentially stacking a lower separator, a first electrode plate, an upper separator, and a second electrode plate at least once based on a winding core C, such as Figure 2 shown.

[0223] The first electrode plate and the second electrode plate have different polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode plate and the second electrode plate may have the electrode plate structure of the above-mentioned embodiment (variant). In addition, the other of the first electrode plate and the second electrode plate may have a conventional electrode plate structure or the electrode plate structure of the above-mentioned embodiment (variant).

[0224] For example, the first polarity is negative polarity and the second polarity is positive polarity. The battery shell 171 is electrically connected to one of the first electrode plate and the second electrode plate to have the first polarity. The first polarity is negative polarity, and the battery shell 171 is connected to the electrode plate with negative polarity. For example, the battery can 171 is connected to the second electrode plate.

[0225] The uncoated portion 146a of the first electrode plate and the uncoated portion 146b of the second electrode plate protrude from the upper and lower portions of the electrode assembly 141, respectively. The rivet terminal 172 is mounted on the closed surface (top surface in the figure) of the battery case 171. The rivet terminal 172 is riveted to the through hole of the battery case 171 through the second gasket 173 with an insulating layer inserted therebetween. The rivet terminal 172 is exposed to the outside in a direction opposite to the direction of gravity. The surface of the rivet terminal 172 is exposed to the outside.

[0226] The rivet terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery shell 171. The terminal exposure portion 172a may be located approximately at the center of the closed surface of the battery shell 171. The maximum diameter of the terminal exposure portion 172a may be greater than the maximum diameter of the through hole formed in the battery shell 171. The terminal insertion portion 172b may be electrically connected to the uncoated portion 146a of the first electrode plate through the approximately central portion of the closed surface of the battery shell 171. The terminal insertion portion 172b may be riveted to the inner surface of the battery shell 171. That is, the end of the terminal insertion portion 171b may have a shape bent toward the inner surface of the battery shell 171. The maximum diameter of the end of the terminal insertion portion 172b may be greater than the maximum diameter of the through hole of the battery shell 171. The rivet terminal 172 is electrically connected to the other of the first electrode plate and the second electrode plate that is not connected to the battery shell 171. For example, the rivet terminal 172 is connected to the first electrode plate having a positive polarity, and thus has the second polarity, ie, the positive polarity.

[0227] The cylindrical battery cell 170 may also include a first current collecting plate 144. The first current collecting plate 144 is made of a conductive metal material, such as aluminum, copper, nickel, etc., and is electrically connected to the uncoated portion 146a of the first electrode plate. The first current collecting plate 144 may include a plurality of irregularities (not shown) formed radially on its lower surface. When radial irregularities are provided, the irregularities may be pressed into the uncoated portion 146a of the first electrode plate by pressing the first current collecting plate 144.

[0228] The first current collecting plate 144 is connected to the end of the uncoated portion 146a of the first electrode plate. The connection between the uncoated portion 146a and the first current collecting plate 144 can be completed, for example, by laser welding. Laser welding can be performed in a manner that partially melts the current collecting plate substrate. In one variation, the welding between the first current collecting plate 144 and the uncoated portion 146a can be performed with a solder inserted therebetween. In this case, the solder may have a lower melting point than the first current collecting plate 144 and the uncoated portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, etc.

[0229] It is preferred that the rivet terminal 172 electrically connected to the uncoated portion 146a of the first electrode plate serves as the first electrode terminal. If the first electrode plate has a positive polarity, the rivet terminal 172 connected thereto becomes a positive terminal.

[0230] The bottom surface of the terminal insertion portion 172b may be welded to the first current collecting plate 144 connected to the uncoated portion 146a of the first electrode plate. An insulating cap 174 made of an insulating material may be inserted between the first current collecting plate 144 and the inner surface of the battery case 171. The insulating cap 174 covers the upper portion of the first current collecting plate 144 and the top edge of the electrode assembly 141. Therefore, a short circuit caused by the peripheral uncoated portion B3 of the electrode assembly 141 contacting the inner surface of the battery case 171 having different polarities may be prevented. The terminal insertion portion 172b of the rivet terminal 172 may be welded to the first current collecting plate 144 through the insulating cap 174.

[0231] The second gasket 173 is inserted between the battery case 171 and the rivet terminal 172 to prevent the battery case 171 and the rivet terminal 172 having opposite polarities from electrically contacting each other. Therefore, the top surface of the battery case 171 having a substantially flat shape can be used as a second electrode terminal of the cylindrical battery cell 170. For example, it can become a negative terminal.

[0232] The second gasket 173 includes a gasket exposed portion 173a and a gasket inserted portion 173b. The gasket exposed portion 173a is inserted between the terminal exposed portion 172a of the rivet terminal 172 and the battery shell 171. The gasket inserted portion 173b is inserted between the terminal inserted portion 172b of the rivet terminal 172 and the battery shell 171. When the terminal inserted portion 172b is riveted, the gasket inserted portion 173b can be deformed together with it to be in close contact with the inner surface of the battery shell 171. The second gasket 173 can be made of, for example, a polymer resin having insulation.

[0233] The gasket exposed portion 173a of the second gasket 173 may have an extended shape to cover the outer peripheral surface of the terminal exposed portion 172a of the rivet terminal 172. When the second gasket 173 covers the outer peripheral surface of the rivet terminal 172, a short circuit may be prevented from occurring during the process of connecting an electrical connection component such as a bus bar to the top surface of the battery case 171 and / or the rivet terminal 172. Although not shown in the drawings, the gasket exposed portion 173a may have an extended shape to cover not only the outer peripheral surface of the terminal exposed portion 172a but also a portion of the top surface.

[0234] When the second gasket 173 is made of a polymer resin, the second gasket 171 may be connected to the battery case 171 and the rivet terminal 172 by thermal fusion. In this case, the airtightness at the connection interface between the second gasket 173 and the rivet terminal 172 and the connection interface between the second gasket 173 and the battery case 171 may be enhanced. Meanwhile, in the case where the gasket exposed portion 173a of the second gasket 173 extends to the top surface of the terminal exposed portion 172a, the rivet terminal 172 may be integrally connected to the second gasket 173 by insertion injection.

[0235] In the top surface of the battery case 171 , a remaining area 175 excluding the area occupied by the rivet terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the rivet terminal 172 .

[0236] The second current collecting plate 176 is connected to the lower portion of the electrode assembly 141. The second current collecting plate 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the uncoated portion 146b of the second electrode plate.

[0237] Preferably, the second current collecting plate 176 is electrically connected to the battery shell 171. To this end, at least a portion of the edge of the second current collecting plate 176 can be inserted and fixed between the inner surface of the battery shell 171 and the first gasket 178b. In one example, at least a portion of the edge of the second current collecting plate 176 can be fixed to the curling portion 180 by welding, while supporting on the bottom surface of the curling portion 180 formed at the lower end of the battery shell 171. The curling portion 180 is formed by crimping the outer peripheral surface of the battery shell 171. In one variation, at least a portion of the edge of the second current collecting plate 176 can be directly welded to the inner wall surface of the battery shell 171.

[0238] The second current collecting plate 176 may include a plurality of irregularities (not shown) radially formed on a surface opposite to the uncoated portion 146b. If irregularities are formed, the irregularities may be pressed into the uncoated portion 146b by pressing the second current collecting plate 176. Preferably, the ends of the second current collecting plate 176 and the uncoated portion 146b may be connected by welding such as laser welding.

[0239] The uncoated portions 146a and 146b are not limited to the structure shown. Therefore, the uncoated portions 146a and 146b may selectively have the uncoated portion structure of the electrode plate of the embodiment (variation) and the conventional uncoated portion structure.

[0240] The sealing body 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 separates 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.

[0241] The cover plate 178a is provided with a venting portion 179. The venting portion 179 corresponds to an area where the thickness of the cover plate 178a is thinner than the surrounding area. The venting portion 179 is structurally weaker than the surrounding area. Therefore, when an abnormality occurs in the cylindrical battery cell 170 and the internal pressure increases to above a certain level, the venting portion 179 may rupture, and the gas generated in the battery shell 171 may be discharged to the outside. The venting portion 179 may be formed continuously or discontinuously while drawing a circle on the cover plate 178a. In a modification, the venting portion 179 may be formed as a straight line pattern or other patterns.

[0242] Preferably, the cover plate 178a is made of a conductive metal material. However, since the first gasket 178b is inserted between the cover plate 178a and the battery case 171, the cover plate 178a does not have electrical polarity. The cover plate 178a seals the open end of the lower portion of the battery case 171 and discharges gas when the internal pressure of the battery cell 170 increases above a critical value.

[0243] In the upper surface of the battery case 171 electrically connected to the uncoated portion 146b of the second electrode plate through the second current collecting plate 176, the remaining area 175 except the rivet terminal 172 is used as a second electrode terminal having a different polarity from the first electrode terminal. When the first electrode terminal, the second electrode terminal and the two electrode terminals are located at the upper part of the cylindrical battery pack cell 170 as described above, electrical connection components such as busbars can be arranged only on one side of the cylindrical battery cell 170. This can simplify the battery pack structure and improve energy density. In addition, since the area 175 used as the second electrode terminal has an approximately flat shape, it is possible to achieve sufficient bonding area for bonding electrical connection components such as busbars. Therefore, the cylindrical battery cell 170 can reduce the resistance at the bonding portion of the electrical connection component to a desired level.

[0244] The cylindrical battery cell 170 may reduce the internal resistance of the battery cell and increase the energy density by using the uncoated portions 146 a , 146 b protruding from the upper and lower portions of the electrode assembly 141 as electrode tabs.

[0245] Meanwhile, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to the illustrated structures and may be replaced with the structures of the above-described embodiments (variations).

[0246] Fig.17 is a cross-sectional view taken along the Y-axis direction, showing a cylindrical battery cell according to another embodiment of the present invention.

[0247] refer to Fig.17 The cylindrical battery cell 200 includes Fig.15 The electrode assembly 110 shown in FIG. Fig.16 The cylindrical battery cells 170 shown are substantially identical.

[0248] refer to Fig.17 , the uncoated portions 146a, 146b of the electrode assembly 110 are bent in the radial direction of the electrode assembly 110, for example, from the periphery toward the core. At this time, since the core-side uncoated portion B1 has a lower height than other portions, it is substantially not bent. The first current collecting plate 144 may be welded to the curved surface of the uncoated portion 146a, and the second current collecting plate 176 may be welded to the curved surface of the uncoated portion 146b.

[0249] In the electrode assembly 110, the height of the core-side uncoated portion B1 is relatively lower than the height of other portions. Fig.15 As shown, in the middle uncoated portion B2, the bending length H of the uncoated portion located at the innermost side is equal to or smaller than the radial length R of the core-side uncoated portion B1.

[0250] Therefore, even when the non-coating portions 146 a , 146 b are bent toward the core, the cavity 112 of the core of the electrode assembly 110 may be opened upward without being closed.

[0251] If the cavity 112 is not closed, the electrolyte injection process is not difficult and the electrolyte injection efficiency is improved. In addition, by inserting a welding jig into the cavity 112, the welding process between the second current collecting plate 176 and the battery case 171 can be easily performed.

[0252] When the uncoated portions 146a, 146b have a segmented structure, if the width and / or height and / or spacing of the segments are adjusted to meet the numerical range of the above-mentioned embodiment, the segments overlap into several layers, which is sufficient to fully achieve welding strength when the segments are bent, and no blank space (gap) is formed on the bent surface. In addition, since the elongation and tensile strength of the current collector 41 are optimized, there is no break or crack between the multiple segments.

[0253] The structure of the non-coating portions 146a, 146b may be changed to the structure of the above-described embodiment (variation) different from that shown in the drawings. In addition, a conventional non-coating portion structure may be applied to any of the non-coating portions 146a, 146b without limitation.

[0254] The cylindrical battery cell of the above embodiment (variation) has a structure in which internal resistance is low, internal short circuit is prevented, and welding strength between the current collecting plate and the uncoated portion is improved. The battery cell can be used to manufacture a battery pack.

[0255] Fig.18 Schematic diagram showing a battery pack according to an embodiment of the present invention.

[0256] The battery pack 300 of the embodiment of the present invention includes an assembly in which a cylindrical battery cell 301 is connected and a battery pack housing 302 for accommodating the assembly. The cylindrical battery cell 301 may be any one of the battery cells of the above-mentioned embodiment (variant). In the drawings, for ease of explanation, components such as busbars, cooling units, and external terminals for electrically connecting the cylindrical battery cells 301 are omitted.

[0257] The battery pack 300 can be installed in a vehicle, such as Fig.19 shown. Fig.19 Schematically shows a vehicle including a battery pack according to an embodiment of the present invention. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheel vehicle or a two-wheel vehicle.

[0258] refer to Fig.19The vehicle V of the embodiment of the present invention includes the battery pack 300 of the embodiment of the present invention. According to the embodiment of the present invention, the vehicle V operates by receiving power from the battery pack 300.

[0259] In addition, although the invention has been described in detail, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since those skilled in the art will clearly understand various changes and modifications within the scope of the invention from this detailed description.

[0260] [Explanation of Reference Numerals]

[0261] 41: Current collector 42: Active material layer

[0262] 43,43a,43b,146a,146b: Uncoated part 44: Insulation coating

[0263] 50,60,70: electrode plates 61,61': sections

[0264] B1: Core side uncoated portion B2: Middle uncoated portion

[0265] B3: Peripheral uncoated part 80, 100, 110, 141: Electrode assembly

[0266] 102, 112: Cavity 144: First collector plate

[0267] 170,301: Cylindrical battery cell 171: Battery case

[0268] 172: Rivet terminal 173: Second washer

[0269] 174: Insulation cap 176: Second current collecting plate

[0270] 178: Sealing body 178a: Cover plate

[0271] 178b: First gasket 179: Exhaust part

[0272] 180: crimping part 181: crimping part

[0273] C: winding core 300: battery pack

[0274] 302: Battery Pack Housing V: Vehicle

Claims

1. An electrode plate for a secondary battery, comprising: Current collector for secondary battery, wherein the elongation is 1.5% to 3.0% and the tensile strength is 25 kgf / mm 2 Up to 35 kgf / mm 2 ;and The active material layer formed on the current collector, wherein the current collector is an aluminum current collector having a sheet shape having a short side and a long side, and including an uncoated portion at an end of the long side of the current collector where the active material layer is not coated, The width of the electrode plate along the short side of the current collector is 60 mm to 110 mm, the length of the electrode plate along the long side of the current collector is 3 m to 5 m, and the arch length of the electrode plate is less than 20 mm, and The length of the uncoated portion measured along the short side direction of the current collector is 2 mm to 20 mm.

2. The electrode plate for a secondary battery according to claim 1, wherein: At least a portion of the uncoated portion is divided into a plurality of sections.

3. The electrode plate for a secondary battery according to claim 2, wherein: The uncoated portion has a cutout in a direction along a short side of the current collector.

4. The electrode plate for a secondary battery according to claim 3, wherein: There was no breaking or cracking of the uncoated portion of the cut area.

5. The electrode plate for a secondary battery according to claim 1, wherein: The energy density per unit area of ​​the active material layer is 1 mAh / cm 2 Up to 6 mAh / cm 2 .

6. The electrode plate for a secondary battery according to claim 1, wherein: The active material comprises a lithium transition metal oxide.

7. An electrode assembly, the electrode assembly being a jelly-roll type electrode assembly, wherein the electrode assembly has a structure in which a first electrode plate and a second electrode plate in a sheet shape and a separator interposed therebetween are wound in one direction, in, At least one of the first electrode plate and the second electrode plate includes a current collector, the current collector is an aluminum current collector having a sheet shape having a short side and a long side and including an uncoated portion at an end of the long side of the current collector where the active material layer is not coated, wherein at least a portion of the uncoated portion is exposed to the outside of the separator and serves as an electrode tab itself, The elongation of the current collector is 1.5% to 3.0%, and the tensile strength is 25 kgf / mm 2 Up to 35 kgf / mm 2 , The width of the first electrode plate or the second electrode plate along the short side of the current collector is 60 mm to 110 mm, the length of the first electrode plate or the second electrode plate along the long side of the current collector is 3 m to 5 m, and the arch length of the first electrode plate or the second electrode plate is less than 20 mm, and The length of the uncoated portion measured along the short side direction of the current collector is 2 mm to 20 mm.

8. The electrode assembly according to claim 7, in, The uncoated portion includes a core-side uncoated portion adjacent to the core portion of the electrode assembly, a peripheral uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the peripheral uncoated portion, and Wherein, at least a portion of the middle uncoated portion is divided into a plurality of sections.

9. The electrode assembly according to claim 8, wherein: The section has a shape in which an upper width is smaller than a lower width.

10. The electrode assembly according to claim 8, wherein: Each of the plurality of sections has a rectangular, trapezoidal, triangular, parallelogram, semicircular, or semi-elliptical structure.

11. The electrode assembly according to claim 8, wherein: The outer peripheral uncoated portion and the core-side uncoated portion have no segment structure in the uncoated portion.

12. The electrode assembly according to claim 8, wherein: The plurality of segments are bent in a radial direction of the electrode assembly and overlapped in several layers.

13. The electrode assembly according to claim 8, wherein: No breaks or cracks are included between the plurality of segments.

14. The electrode assembly according to claim 8, wherein: The energy density per unit area of ​​the active material layer is 1 mAh / cm 2 Up to 6 mAh / cm 2 .

15. The electrode assembly according to claim 8, wherein: The active material comprises a lithium transition metal oxide.

16. A cylindrical battery cell comprising: A jelly-roll type electrode assembly having a structure in which a first electrode plate and a second electrode plate in a sheet shape and a separator interposed therebetween are wound in one direction; a battery case configured to accommodate the electrode assembly and electrically connected to any one of the first electrode plate and the second electrode plate to have a first polarity; a sealing body configured to seal an open end of the battery case; and a terminal electrically connected to the other of the first electrode plate and the second electrode plate to have a second polarity and having a surface exposed to the outside, wherein at least one of the first electrode plate and the second electrode plate includes a current collector, the current collector is an aluminum current collector, the current collector has a sheet shape having a short side and a long side, and includes an uncoated portion at an end of the long side of the current collector where the active material layer is not coated, wherein at least a portion of the uncoated portion is exposed to the outside of the separator and serves as an electrode tab itself, The elongation of the current collector is 1.5% to 3.0%, and the tensile strength is 25 kgf / mm 2 Up to 35 kgf / mm 2 , The width of the first electrode plate or the second electrode plate along the short side of the current collector is 60 mm to 110 mm, the length of the first electrode plate or the second electrode plate along the long side of the current collector is 3 m to 5 m, and the arch length of the first electrode plate or the second electrode plate is less than 20 mm, and The length of the uncoated portion measured along the short side direction of the current collector is 2 mm to 20 mm.

17. The cylindrical battery cell according to claim 16, in, The uncoated portion includes a core-side uncoated portion adjacent to the core portion of the electrode assembly, a peripheral uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the peripheral uncoated portion, and Wherein, at least a portion of the middle uncoated portion is divided into a plurality of sections.

18. The cylindrical battery cell according to claim 17, wherein: No breaks or cracks are included between the plurality of segments.

19. The cylindrical battery cell according to claim 17, in, At least a portion of the middle uncoated portion is bent from the periphery toward the core, wherein a cavity is provided in the core of the electrode assembly, and Wherein, the cavity is not closed by the curved structure of the middle uncoated portion.

20. The cylindrical battery cell of claim 16, further comprising a current collecting plate electrically connected to an uncoated portion of the second electrode plate having the first polarity and configured to connect at least a portion of an edge thereof to a side wall of the battery case.

21. The cylindrical battery cell according to claim 16, wherein: The sealing body includes a non-polar cover plate and a gasket surrounding the edge of the cover plate and being crimped to the top end of the battery case.

22. The cylindrical battery cell according to claim 16, wherein: The battery case includes a rivet terminal installed to be insulated in a through hole formed in a central portion of a closed surface and electrically connected to the first electrode plate to have a second polarity.

23. The cylindrical battery cell according to claim 16, wherein: The energy density per unit area of ​​the active material layer is 1 mAh / cm 2 Up to 6 mAh / cm 2 .

24. The cylindrical battery cell according to claim 16, wherein: The active material comprises a lithium transition metal oxide.

25. A battery pack comprising at least one battery cell as claimed in any one of claims 16 to 24.

26. A vehicle comprising at least one battery pack according to claim 25.

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