Electrode assembly, cylindrical battery, battery pack including said cylindrical battery, and automobile

Abstract

The present invention discloses an electrode assembly, a cylindrical battery, a battery pack, and an automobile. The electrode assembly includes a first electrode, a second electrode, which are wound around a single axis and define a core and an outer surface, and a separator membrane interposed between the first electrode and the second electrode. At least one of the first electrode and the second electrode includes a plain portion extending in the winding direction along its long edge. The plain portion includes a plurality of segmental sections that are separated by cutting grooves formed along the winding direction and are independently foldable. The plurality of segmental sections are folded toward the core to form a folded surface region at one end of the electrode assembly. At least a portion of the plurality of segmental sections includes a folded end portion.

Description

Technical Field

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

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0105883 filed on August 11, 2023, and Korean Patent Application No. 10-2024-0107867 filed on August 12, 2024, and all the contents disclosed in the specifications and drawings of the applications are incorporated herein.

Background Art

[0003] Secondary batteries (batteries) with high applicability for each product group and having electrical characteristics such as high energy density are generally applied not only to portable devices but also to electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc. driven by motors.

[0004] Such secondary batteries have not only the primary advantage of significantly reducing the use of fossil fuels but also the advantage of generating no by-products due to energy use, and thus are environmentally friendly and attracting attention as a new energy source for improving energy efficiency.

[0005] Currently, secondary batteries such as lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries are widely used. The operating voltage of such a unit secondary battery, that is, a unit battery, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a plurality of batteries are connected in series to form a battery pack. Also, depending on the charge and discharge capacity required for the battery pack, a plurality of batteries may be connected in parallel to form a battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection form can be variously set according to the required output voltage and / or charge and discharge capacity.

[0006] On the other hand, as types of unit secondary batteries, cylindrical, rectangular, and pouch-type batteries are known. In the case of a cylindrical battery, a separator, which is an insulator, is interposed between the positive electrode and the negative electrode, and this is wound up to form a jelly-roll type electrode assembly, which is inserted into the inside of a battery housing to constitute a battery. The battery housing is called a battery can in the art. Also, strip-shaped electrode tabs are connected to the plain portions of the positive electrode and the negative electrode respectively, and the electrode tabs electrically connect between the electrode assembly and the electrode terminals exposed outside. For reference, the positive electrode terminal is the cap of the sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, in a conventional cylindrical battery having such a structure, since current is concentrated in the strip-shaped electrode tab coupled to the positive electrode plain portion and / or the negative electrode plain portion, there is a problem that the resistance is large, heat generation is much, and the current collection efficiency is not good.

[0007] In the case of a small cylindrical battery having a form factor of 1865 (diameter: 18 mm, height: 65 mm) or 2170 (diameter: 21 mm, height: 70 mm), resistance and heat generation are not much of a problem. However, when increasing the form factor for applying the cylindrical battery to an electric vehicle, there may occur a problem that the cylindrical battery catches fire while generating a large amount of heat around the electrode tab during the rapid charging process.

[0008] To solve these problems, a cylindrical battery (a so-called tab-less cylindrical battery) has been proposed in which a blank positive electrode section and a blank negative electrode section are located at the upper and lower ends of a jelly roll-type electrode assembly, respectively, and a current collector is welded to these blank sections to improve current collection efficiency.

[0009] Figures 1 to 3 illustrate the manufacturing process of a tablet cylindrical battery. Figure 1 shows the structure of the electrodes, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding the current collector to the bent surface area of ​​the plain section.

[0010] Referring to Figures 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-like current collector 20, and include a plain section 22 on one of the longer sides along the winding direction (X-axis). The longer side refers to the side that is parallel to the X-axis direction and has a relatively longer length.

[0011] Electrode assembly A is manufactured by sequentially stacking the positive electrode 10 and the negative electrode 11 together with two separation films 12, as shown in Figure 2, and then winding them in one direction (X-axis direction) around one axis of the core 33. The stacking order of the positive electrode 10 and the negative electrode 11 may be reversed from that shown. The plain areas of the positive electrode 10 and the negative electrode 11 are positioned in opposite directions to each other.

[0012] After the winding process, the blank positive electrode portion 10a and the blank negative electrode portion 11a are bent towards the core. Then, the current collectors 30 and 31 are welded to the blank portions (blank positive electrode portion 10a and blank negative electrode portion 11a), respectively, to join them.

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

[0014] On the other hand, the bent portions of the plain sections (positive electrode plain section 10a, negative electrode plain section 11a) to which the current collectors 30 and 31 are welded overlap in multiple layers, as shown in Figure 3. Therefore, the bent surface region formed as the plain sections (positive electrode plain section 10a, negative electrode plain section 11a) are bent has almost no gap for the electrolyte to pass through in the winding axis direction. This is because the gap between winding turns that existed immediately after winding is almost eliminated during the bending process of the plain sections (positive electrode plain section 10a, negative electrode plain section 11a). Consequently, electrode assemblies manufactured with a conventional tabless structure have the disadvantage of a slow electrolyte impregnation rate. This is because there is not enough gap in the bent surface region for the electrolyte to move into the interior of the electrode assembly. [Overview of the project] [Problems that the invention aims to solve]

[0015] The present invention was conceived against the background of the prior art described above, and aims to provide an electrode assembly in which the structure of the plain part of the electrode is improved so that a gap into which an electrolyte can be impregnated is sufficiently formed in the folded surface region of the plain part of the electrode assembly.

[0016] Furthermore, another objective of the present invention is to provide a battery including an electrode assembly with an improved structure, a battery pack including the battery, and an automobile including the battery pack.

[0017] The technical problems that this invention aims to solve are not limited to those described above, and other problems not mentioned will be clearly understood by an ordinary person from the description of the invention described later. [Means for solving the problem]

[0018] An electrode assembly according to one aspect of the present invention for solving the above-mentioned technical problems is an electrode assembly comprising a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode, which are wound around a single axis to define a core and an outer surface, wherein at least one of the first electrode and the second electrode includes a plain portion extending in the winding direction along its long edge, the plain portion includes a plurality of segmental sections that are separated by cutting grooves formed along the winding direction and can be independently folded, the plurality of segmental sections are folded toward the core to form a folded surface region at one end of the electrode assembly, and at least a portion of the plurality of segmental sections includes a folded end portion.

[0019] In this invention, a segment containing a folded end is defined as a folded end segment, and the number of blank areas that intersect with a hypothetical straight line passing through the center of the folded end is defined as the number of folds at the folded end.

[0020] The aforementioned bent surface region may include a plurality of end-folded sections.

[0021] The bent end portion has two or more bends and can form gaps between adjacent segments in the radial direction of the electrode assembly.

[0022] The gap may have a separation distance between adjacent segments in the radial direction of the electrode assembly that corresponds to the thickness of the bent end.

[0023] The plurality of end-bent segments can be arranged on the bent surface region in a regular or irregular pattern along the radial or circumferential direction of the electrode assembly.

[0024] The bent surface region may include a radial section in which the number of end bent segments arranged in the circumferential direction increases stepwise or gradually from the core toward the outer surface.

[0025] The bent surface region may include a radius section in which the number of bends of the bent end increases stepwise or gradually from the core toward the outer circumferential surface.

[0026] The bent surface region may include a radius section in which the number of bends of the bent end is maintained the same from the core to the outer surface.

[0027] The height of the aforementioned multiple end-fold sections may increase in stages from the core of the electrode assembly toward the outer circumferential surface. In this case, the folded surface region may include a radial section in which the number of folds at the folded end also increases with the increase in the height of the end-fold sections.

[0028] The bent surface region may include a radial section in which the uniaxial width of the plain portion forming the bent end increases stepwise or gradually from the core of the electrode assembly toward the outer surface.

[0029] In this invention, the number of blank areas at any point in the folded surface area that intersects with a virtual line passing through the folded surface area parallel to the uniaxial direction is defined as the number of blank area layers at that point.

[0030] The aforementioned bent surface region may include a section where the number of layers increases and a section where the number of layers is uniform.

[0031] The section with increasing number of layers is located close to the outer surface of the electrode assembly, and the section with a uniform number of layers may be located between the section with increasing number of layers and the core of the electrode assembly.

[0032] The number of end-folded sections included in the uniform-layer section may be even greater than the number of end-folded sections included in the increased-layer section.

[0033] The number of folds at the folded end included in the section with a uniform number of layers may be even greater than the number of folds at the folded end included in the section with an increased number of layers.

[0034] The bent end may have a structure that is folded in a jelly roll shape, a structure that is folded in a zigzag shape, or a structure that is folded randomly.

[0035] A cylindrical battery according to another aspect of the present invention for solving the above-mentioned technical problems includes: an electrode assembly having a first electrode, a second electrode, and a separator membrane interposed between the first electrode and the second electrode, which are wound around a single axis to define a core and an outer surface, and which includes at least one of the above-mentioned features; a battery housing having an open end and a closed end, through which the electrode assembly is housed and electrically connected to the second electrode of the electrode assembly; a seal that seals the open end of the battery housing; and a terminal electrically connected to the first electrode of the electrode assembly, with its surface exposed to the outside of the battery housing.

[0036] The aforementioned bent surface region may be formed by bending a plurality of segments contained within the plain portion of the first electrode.

[0037] The cylindrical battery may further include a first current collector plate that electrically connects the bent surface region formed by the plain portion of the first electrode to the terminal.

[0038] The terminal can be mounted in a through-hole formed in the closed end of the battery housing in a manner that provides insulation from the battery housing. A gasket may be interposed between the terminal and the through-hole.

[0039] The terminal may include a terminal exposure portion exposed to the outside of the closed end and a terminal insertion portion extending from the terminal exposure portion and inserted into the inside of the battery housing through the through hole.

[0040] The periphery of the bottom of the terminal insertion portion can be riveted toward the inner surface of the closed end.

[0041] The sealing body may include a cap plate that seals the open end of the battery housing.

[0042] A gasket may be interposed between the periphery of the cap plate and the open end of the battery housing.

[0043] The terminal may be the cap plate.

[0044] The aforementioned bent surface region may be formed by bending a plurality of segments contained within the plain portion of the second electrode.

[0045] The cylindrical battery may further include a second current collector plate that electrically connects the bent surface region formed by the plain portion of the second electrode to the side wall of the battery housing.

[0046] The battery housing may include a beading portion formed by pressing the outer circumferential surface near the open end.

[0047] The periphery of the second current collector plate may be interposed between the gasket and the side wall of the battery housing.

[0048] The periphery of the second current collector plate may come into contact with the side wall of the battery housing, for example, the beading portion.

[0049] If a beading portion is not provided on the side wall of the battery housing, the side wall may extend linearly between the closed end and the open end. In this case, the periphery of the cap plate may be welded to the open end.

[0050] The second current collector plate can be welded to the cap plate in part.

[0051] The second current collector plate can be electrically connected to the cap plate.

[0052] At least a portion of the inner region of the periphery of the cap plate can be welded to a bent surface region formed by the plain portion of the second electrode facing the cap plate. In this case, the cap plate can replace the function of the second current collector plate.

[0053] Yet another technical problem of the present invention is solved by a battery pack comprising multiple cylindrical batteries as described above.

[0054] Yet another technical problem of the present invention can also be solved by an automobile including the battery pack. [Effects of the Invention]

[0055] According to one aspect of the present invention, the structure of the end portion of the segment can be improved to sufficiently form gaps in the radial and / or circumferential directions in the bent surface region formed by bending the segment, which can be used as an electrolyte impregnation path, thereby shortening the electrolyte impregnation time.

[0056] According to another aspect of the present invention, a cylindrical battery can be provided that includes an electrode assembly having improved electrolyte impregnation, low internal resistance, and improved welding strength between the current collector and the blank portion, a battery pack including the cylindrical battery, and an automobile.

[0057] The present invention can produce a variety of other effects. These will be described later with reference to each embodiment, but we will omit explanations of effects that can be easily inferred by an ordinary engineer.

[0058] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, are intended to further illustrate the technical idea of ​​the invention; therefore, the invention shall not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0059] [Figure 1] This is a plan view showing the structure of electrodes used in the manufacture of conventional tablet cylindrical batteries. [Figure 2] This diagram shows the electrode winding process for a conventional cylindrical tablet battery. [Figure 3]This diagram illustrates the process of welding a current collector to the bent surface area of ​​the plain section in a conventional tabletless cylindrical battery. [Figure 4] This is a plan view showing the structure of an electrode according to an embodiment of the present invention. [Figure 5] This is a plan view illustrating an electrode structure including a plurality of end-bent sections according to an embodiment of the present invention. [Figure 6] This figure shows a cross-sectional structure of a bent end along the line A-A' in Figure 5. [Figure 7] This figure shows another cross-sectional structure of the bent end along the line A-A' in Figure 5. [Figure 8] This figure shows yet another cross-sectional structure of the bent end along the line A-A' in Figure 5. [Figure 9] This figure shows yet another cross-sectional structure of the bent end along the line A-A' in Figure 5. [Figure 10a] This is a perspective view showing the upper structure of an electrode assembly with a bent surface region formed according to an embodiment of the present invention. [Figure 10b] This is a plan view schematically showing the position of the bent end on the bent surface region according to an embodiment of the present invention, indicated by dotted boxes. [Figure 10c] This is a cross-sectional view obtained by cutting a portion of the bent surface region according to an embodiment of the present invention along the winding axis direction of the electrode assembly. [Figure 11] This is a cross-sectional view of a jelly roll-type electrode assembly, in which electrodes according to embodiments of the present invention are applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the winding axis direction (Y axis). [Figure 12] This is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention, cut along the winding axis (Y axis). [Figure 13] This is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the winding axis (Y axis). [Figure 14] This figure schematically shows the configuration of a battery pack according to an embodiment of the present invention. [Figure 15] This figure schematically shows an automobile including a battery pack according to an embodiment of the present invention. [Modes for carrying out the invention]

[0060] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used herein and in the claims shall not be interpreted in their usual and dictionary sense, but rather in a sense and concept that corresponds to the technical idea of ​​the present invention, in accordance with the principle that the inventor himself may appropriately define the concept of terms in order to best describe the invention.

[0061] Therefore, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the invention. It should be understood that there are various equivalents and modifications that can be substituted for these at the time of filing this application.

[0062] Furthermore, to aid in understanding the invention, the accompanying drawings are not shown to actual scale, and the dimensions of some components may be exaggerated. Also, the same component in different embodiments may be assigned the same reference numeral.

[0063] Furthermore, for two comparison targets to be "identical" means "substantially identical." Therefore, "substantially identical" may include cases where the deviation is considered low in the industry, for example, a deviation of 10% or less. Also, for a parameter to be uniform in a domain may mean that it is uniform in terms of the average within that domain.

[0064] While terms such as "first," "second," etc., are used to indicate a variety of components, these components are not limited by such terms. These terms are simply used to distinguish one component from another, and unless otherwise specified, the first component may also be the second component.

[0065] Throughout the specification, unless otherwise specified, each component may be singular or plural.

[0066] To say that any component is placed "above (or below)" or "above (or below)" a component means not only that the component is placed in contact with the upper (or lower) surface of the component, but also that other components may be interposed between the component and any component placed above (or below) it.

[0067] Furthermore, when one component is described as being "connected," "joined," or "linked" to another component, this includes not only cases where the components are directly connected or linked to each other, but also cases where other components are "interposed" between each component, or where each component is "connected," "joined," or "linked" through other components.

[0068] Throughout this specification, "A and / or B" means A, B, or A and B unless otherwise specified, and "C-D" means C to D unless otherwise specified.

[0069] For the sake of explanation, in this specification, the direction along the longitudinal direction of the winding shaft of the electrode assembly wound into a jelly roll is referred to as the axial direction (Y-axis). The direction surrounding the winding shaft is referred to as the circumferential direction or outer peripheral direction (X-axis direction). The direction approaching or moving away from the winding shaft is referred to as the radial direction or radial direction (Z-axis direction). Of these, the direction approaching the winding shaft is referred to as the centripetal direction, and the direction moving away from the winding shaft is referred to as the centrifugal direction.

[0070] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly may be a jelly roll type electrode assembly having a structure in which a sheet-like first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound in one direction.

[0071] At least one of the first electrode and the second electrode includes a plain portion at the long edge in the winding direction where the active material is not coated. At least a portion of the plain portion is used as an electrode tab. The plain portion includes a core-side plain portion adjacent to the core of the electrode assembly, an outer-circumferential plain portion adjacent to the outer circumferential surface of the electrode assembly, and an intermediate plain portion interposed between the core-side plain portion and the outer-circumferential plain portion.

[0072] Preferably, at least one of the plain core portion and the plain outer periphery portion is relatively lower in height than the intermediate plain portion.

[0073] Figure 4 is a plan view showing the structure of the electrode 60 according to an embodiment of the present invention.

[0074] Referring to Figure 4, the electrode 60 of the embodiment includes a current collector 41 made of metal foil and an active material layer 42. The metal foil may be a conductive metal, such as aluminum or copper, and is appropriately selected depending on the polarity of the electrode 60. The active material layer 42 is formed on at least one surface of the current collector 41. The active material layer 42 is formed along the winding direction (X-axis). The electrode 60 includes a plain portion 43 at the long side end in the winding direction (X-axis). The plain portion 43 is a part of the current collector 41 that is not coated with the active material.

[0075] In the electrode 60, the width of the active material portion in the short-side direction of the current collector 41 is 50 mm to 120 mm, and the length of the active material portion in the long-side direction of the current collector 41 may be 3 m to 5 m.

[0076] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the blank area 43. The insulating coating layer 44 is formed such that at least a portion of it overlaps with the boundary between the active material layer 42 and the blank area 43. The insulating coating layer 44 prevents short circuits between two electrodes of opposite polarity that are facing each other with a separator film in between. The insulating coating layer 44 may cover the boundary portion between the active material layer 42 and the blank area 43 with a width of 0.3 mm to 5 mm. The insulating coating layer 44 contains a polymer resin and may contain inorganic fillers such as SiO2 and Al2O3. The portion of the current collector 41 covered by the insulating coating layer 44 can be considered a blank area because it is not a region coated with the active material layer.

[0077] The plain portion 43 includes a core-side plain portion B1 adjacent to the core side of the electrode assembly, an outer-circumferential plain portion B3 adjacent to the outer-circumferential side of the electrode assembly, and an intermediate plain portion B2 interposed between the core-side plain portion B1 and the outer-circumferential plain portion B3.

[0078] The plain core portion B1, the plain outer peripheral portion B3, and the plain intermediate portion B2 can be defined as the plain region adjacent to the core, the plain region adjacent to the outer peripheral, and the plain region excluding these areas, respectively, when the electrode 60 is wound up as a jelly roll-type electrode assembly.

[0079] Hereinafter, the plain core section B1, the plain outer perimeter section B3, and the plain intermediate section B2 will be referred to as the first section, the second section, and the third section, respectively.

[0080] For example, the first portion B1 may be a plain area of ​​the electrode region including the innermost winding turn, and the second portion B3 may be a plain area of ​​the electrode region including the outermost winding turn. The winding turns can be counted relative to the core-side end of the electrode assembly.

[0081] As another example, the boundary between the first part B1 and the third part B2 can be appropriately defined as the point where the height (or variation pattern) of the plain area of ​​the electrode assembly substantially changes from the core side to the outer circumference side, or as a predetermined percentage point relative to the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius).

[0082] The boundary between the third part B2 and the second part B3 can be defined as the point where the height (or variation pattern) of the plain area substantially changes from the outer circumference of the electrode assembly toward the core, or as a predetermined percentage point relative to the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius). Once the boundary between the first part B1 and the third part B2, and the boundary between the third part B2 and the second part B3 are identified, the third part B2 can be automatically identified.

[0083] If only the boundary between the first part B1 and the third part B2 is specified, the boundary between the third part B2 and the second part B3 can be appropriately selected at a point near the outer circumference of the electrode assembly. For example, the second part may be defined as the plain portion of the electrode area constituting the outermost winding turn. Conversely, if only the boundary between the third part B2 and the second part B3 is specified, the boundary between the first part B1 and the third part B2 can be appropriately selected at a point near the core of the electrode assembly. For example, the first part B1 may be defined as the plain portion of the electrode area constituting the innermost winding turn.

[0084] This does not rule out the possibility of other structures intervening between the first part B1 and the third part B2. Nor does it rule out the possibility of other structures intervening between the third part B2 and the second part B3.

[0085] In electrode 60, the heights of the first portion B1 and the second portion B3 are 0 or greater and relatively lower than the third portion B2. Also, the heights of the first portion B1 and the second portion B3 may be the same or different. In the winding direction, the length of the third portion B2 is longer than the lengths of the first portion B1 and the second portion B3.

[0086] Width d of Part B1 B1 The design applies the condition that when the plain portion of the third part B2 is folded towards the core, it does not block the core of the electrode assembly. The core refers to the cavity located at the winding center of the electrode assembly. The width d of the first part B1 B1 The width d of the first part B1 may increase in proportion to the fold length of the plain section closest to the core. B1This can be set to 180mm to 350mm depending on the diameter of the electrode assembly core and the bending length of the plain area closest to the core.

[0087] The plain portion of the third section B2 may include a plurality of segments 61 that are separated by cutting grooves 63 formed along the winding direction (X-axis) and can be folded independently.

[0088] Multiple subsections 61 may have a gradually increasing height from the core side to the outer periphery side. Alternatively, multiple subsections 61 may maintain a uniform height from the core side to the outer periphery side.

[0089] The multiple segments 61 have a geometric shape in which the width decreases from the bottom to the top. The geometric shape may be a trapezoid. The geometric shape can be transformed into various shapes such as a quadrilateral or parallelogram.

[0090] Multiple segments 61 may be notched with a laser. Cutting grooves 63 are formed between the segments 61 along the winding direction (X-axis). When the shape of the segments 61 is rectangular or trapezoidal, the cutting grooves 63 may be linear. Multiple segments 61 can be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0091] At least some of the multiple sections 61 may include a folded end portion 61a.

[0092] Figure 5 is a plan view illustrating the structure of an electrode 60 including a plurality of bent end sections 61' according to an embodiment of the present invention.

[0093] Figures 6 to 9 show various cross-sectional structures of the bent end along the line A-A' in Figure 5.

[0094] Referring to Figures 4 to 9, the folded end portion 61a is formed on only a portion of the multiple subsections 61. The subsection 61 containing the folded end portion 61a is defined as the end folded subsection 61'. The folded end portion 61a is formed by folding the end of the end folded subsection 61' at least once. The portion of the end folded subsection 61' that forms the folded end portion 61a is the area above the dotted line (see Figure 4). The folded end portion 61a in Figure 4 is in its state before folding.

[0095] In the bent end section 61', the width of the portion forming the bent end 61a may be the same or different. Here, the width is the width in the winding axis direction (Y axis).

[0096] In the bent end section 61', the width of the portion forming the bent end 61a may increase or decrease in steps or gradually from the core side of the electrode assembly toward the outer circumference.

[0097] In the bent end section 61', the width of the portion forming the bent end 61a may vary irregularly from the core side of the electrode assembly toward the outer circumference.

[0098] The bent pattern of the bent end portion 61a may be a linearly wound jelly roll structure, as shown in Figure 6. The bent end portion 61a may be positioned in the direction of the core of the electrode assembly. Contrary to the illustration, the bent end portion 61a may be positioned toward the outer circumferential surface of the electrode assembly.

[0099] As another example, the bend pattern of the bent end portion 61a may be a jelly roll structure wound in an arc shape, as shown in Figure 7. The bent end portion 61a may be positioned in the direction of the core of the electrode assembly. Contrary to the illustration, the bent end portion 61a may be positioned toward the outer circumferential surface of the electrode assembly.

[0100] As yet another example, the bending pattern of the bent end portion 61a may be a zigzag structure, as shown in Figure 8. The bent end portion 61a may be positioned in the direction of the core of the electrode assembly. Contrary to the illustration, the bent end portion 61a may be positioned toward the outer circumferential surface of the electrode assembly.

[0101] As yet another example, the bending pattern of the bent end portion 61a may be a randomly bent structure, as shown in Figure 9. In this case, a portion of the bent end portion 61a may be positioned toward the core direction of the electrode assembly, and the other portion of the bent end portion 61a may be positioned toward the outer circumferential surface of the electrode assembly.

[0102] A number of bends can be defined for the bent end portion 61a.

[0103] As shown in Figures 6 to 9, the number of folds can be the number of blank areas that intersect with a hypothetical straight line L passing through the center 62 of the folded end 61a. The hypothetical straight line L may be substantially perpendicular to the blank area excluding the folded end 61a. The center 62 of the folded end 61a may be the centroid of the projected portion when the folded end 61a is projected onto a predetermined plane. The plane onto which the folded end 61a is projected may be the plane on which the end fold section 61' exists. The number of folds of the folded end 61a included in the end fold section 61' exemplified in Figures 6 to 9 is 4. If the structure of the folded end 61a changes, the number of folds may also change.

[0104] If electrode 60 is included as an electrode in a jelly roll-type electrode assembly, the multiple segmental sections 61 and the multiple end-bent segmental sections 61' may extend and protrude outside the separation membrane along the winding axis direction (Y axis) of the electrode assembly.

[0105] Multiple subsections 61 and multiple end-folded subsections 61' can be folded radially toward the core of the electrode assembly, for example, to form a folded surface region at one end of the electrode assembly. The folding point may be near the lower end of the cutting groove 63. The folding point may be located at a distance of 1 mm or less above the lower end of the cutting groove 63. The folded surface region is approximately perpendicular to the winding axis direction (Y axis).

[0106] Figure 10a is a perspective view showing the upper structure of an electrode assembly JR in which a bent surface region F is formed according to an embodiment of the present invention, and Figure 10b is a plan view schematically showing the position of the bent end portion 61a on the bent surface region F with a dotted box. In Figure 10b, the structure in which the segment 61 and the end bent segment 61' overlap radially is not shown. Figure 10c is a cross-sectional view obtained by cutting a part of the bent surface region F along the winding axis direction (Y axis) of the electrode assembly JR.

[0107] Referring to Figures 10a, 10b, and 10c, the bent ends 61a contained in the bent end sections 61' have two or more bends, and gaps G can be formed between adjacent sections 61 in the radial direction of the electrode assembly JR. The gaps G can provide a path for the electrolyte E to impregnate into the interior of the electrode assembly JR. Since there are multiple gaps G formed by multiple bent end sections 61' in the bent surface region F, the electrolyte impregnation rate increases. This makes it possible to shorten the electrolyte injection time.

[0108] The gap G may have a separation distance between adjacent segments 61 in the radial direction of the electrode assembly JR, corresponding to the thickness of the bent end 61a. The thickness of the bent end 61a can be defined as the maximum value among the thicknesses measured at multiple points on the bent end 61a. The more times the bent end 61a is folded, the greater the separation distance of the gap G, and the more the electrolyte impregnation rate can be improved.

[0109] Referring to Figure 10b, the multiple end bent sections 61' can be arranged on the bent surface region F in a regular or irregular pattern along the radial or circumferential direction of the electrode assembly JR.

[0110] In another embodiment, the bent surface region F may include a radial section in which the number of end bent segments 61' arranged circumferentially increases stepwise or gradually from the core C of the electrode assembly JR toward the outer surface.

[0111] In yet another form, the bent surface region F may include a radial section in which the number of bends of the bent end portion 61a increases stepwise or gradually from the core C of the electrode assembly JR toward the outer periphery. That is, in this radial section, the number of bends of the bent end portion 61a located closer to the core C may be smaller than the number of bends of the bent end portion 61a located closer to the outer periphery.

[0112] In yet another form, the bent surface region F may include a radial section in which the number of folds of the bent end portion 61a is maintained at the same rate from the core C of the electrode assembly JR toward the outer circumferential surface. That is, within this radial section, the number of folds of the bent end portion 61a may be the same.

[0113] In another configuration, the height of the end bend section 61' may increase gradually from the core C of the electrode assembly JR toward the outer circumference (see Figure 4). In this case, the bend surface region F may include a radial section in which the number of bends of the bend end 61a increases along with the increase in the height of the end bend section 61'. That is, in this radial section, the number of bends of the bend end 61a included in the relatively low-height end bend section 61' may be smaller than the number of bends of the bend end 61a included in the relatively high-height end bend section 61'.

[0114] In yet another form, the bent surface region F may include a radial section in which the width of the plain portion forming the bent end 61a in the winding axis direction (Y axis) increases stepwise or gradually from the core C of the electrode assembly JR toward the outer surface.

[0115] According to the above-described configuration, the electrolyte impregnation rate can be improved by relatively increasing the number of end-fold sections 61' and / or the number of folds of the folded end 61a, which are located in the radial section of the folded surface region F where the electrolyte impregnation rate is slow.

[0116] Referring to Figure 10c, any point r on the bent surface region F k A virtual straight line L parallel to the winding axis (Y axis) k When you draw a line, the virtual line L kThe number of plain areas that intersect with the line can be defined as the number of plain area layers at that point. k When passing through the bent end 61a, the number of plain layered sections increases by only 1. Point r shown in Figure 10c k The number of layers in the plain section is 6.

[0117] In the bent surface region F, the number of plain layered sections gradually increases from the outer surface toward the core, and once it reaches a predetermined value, a radial section appears in which the number of plain layered sections is maintained uniformly. The uniform layered section S2 is the radial section of the electrode assembly JR in which the number of plain layered sections is maintained substantially the same. "Substantially the same" includes cases where there is a deviation of less than 10%.

[0118] The bent surface region F may include a layer number increasing section S1 and a layer number uniform section S2. The layer number increasing section S1 is located near the outer circumferential surface of the electrode assembly JR. The layer number uniform section S2 is located between the layer number increasing section S1 and the core C of the electrode assembly JR. The length of the layer number uniform section S2 is longer than the length of the layer number increasing section S1.

[0119] In Figure 10c, in the layer count increase section S1, the number of plain layered sections increases from 1 to 13. In the uniform layer count section S2, the number of plain layered sections is maintained at 13. In the uniform layer count section S2, the number of plain layered sections can increase to more than 13 if the length of the segment 61 and the end-folded segment 61' increases.

[0120] In the uniform layer count section S2, the number of plain layers is greater than in the increasing layer count section S1, resulting in a slower electrolyte impregnation rate. Consequently, the number of end-folded sections 61' in the uniform layer count section S2 may be greater than the number of end-folded sections 61' in the increasing layer count section S1. Alternatively, the number of folds of the folded ends 61a in the uniform layer count section S2 may be greater than the number of folds of the folded ends 61a in the increasing layer count section S1. In such a case, the electrolyte impregnation rate in the uniform layer count section S2, where the impregnation rate is slow, can be improved.

[0121] Referring further to Figures 4 and 5, when bending the plain section 43, it is preferable to provide a predetermined gap between the lower end of the cutting groove between the segment pieces 61 and the active material layer 42 in order to prevent damage to the active material layer 42 and / or the insulating coating layer 44. This is because stress is concentrated near the lower end of the cutting groove 63 when the plain section 43 is bent. The gap may vary along the winding direction of the electrode 60. The gap is preferably 0.2 mm to 4 mm, more preferably 1.5 mm to 2.5 mm. By adjusting the gap to the above numerical range, it is possible to prevent damage to the active material layer 42 and / or the insulating coating layer 44 near the lower end of the cutting groove 63 due to the stress generated when bending the plain section 43. In addition, the gap can prevent damage to the active material layer 42 and / or the insulating coating layer 44 due to notches or tolerances during cutting of the segment pieces 61.

[0122] The lower end of the cutting groove 63 and the insulating coating layer 44 can be separated by 0.5 mm to 2.0 mm. When the electrode 60 is wound up, the end of the insulating coating layer 44 in the direction of the winding axis (Y axis) can be located in the range of -2 mm to 2 mm along the winding axis direction with respect to the end of the separation membrane. The insulating coating layer 44 prevents short circuits between two electrodes of opposite polarity that are facing each other with the separation membrane in between, and can support the bending point when the dividing section 61 is bent. To improve the short-circuit prevention effect between the two electrodes, the insulating coating layer 44 can be exposed on the outside of the separation membrane. Furthermore, to further maximize the short-circuit prevention effect between the two electrodes, the width of the insulating coating layer 44 may be increased so that the end of the insulating coating layer 44 in the direction of the winding axis (Y axis) is located above the lower end of the cutting groove 63. In one example, the end of the insulating coating layer 44 in the direction of the winding axis can be located in the range of -2 mm to +2 mm with respect to the lower end of the cutting groove 63. The thickness of the insulating coating layer 44 may be thinner than that of the active material layer. In this case, a gap may exist between the surface of the insulating coating layer 44 and the separation film.

[0123] The plurality of segment pieces 61 may form a plurality of segment piece groups from the core side toward the outer peripheral side. At least one of the width, height, and separation pitch of the segment pieces belonging to the same segment piece group may be substantially the same. Preferably, the width, height, and separation pitch of the segment pieces belonging to the same segment piece group may be the same.

[0124] The width of the segment piece 61 substantially corresponds to the width at the lower end. The width of the segment piece 61 may be 1 mm to 11 m. The width of the segment piece 61 may increase stepwise or gradually as the radius r of the winding turn increases.

[0125] The height of the segment piece 61 substantially corresponds to the shortest distance between the upper end and the lower end. The height of the segment piece 61 may be 2 mm to 10 mm. The height of the segment piece 61 may increase stepwise or gradually along the radial direction of the electrode assembly.

[0126] The separation pitch P of the segment piece 61 corresponds to the distance between two points where a straight line passing through the lower end of the cutting groove in the winding direction intersects two straight lines extending from the side edges of the segment piece 61 on both sides of the cutting groove. The separation pitch P of the segment piece 61 may be 0.05 to 1 mm.

[0127] When the segment piece 61 is approximated to a trapezoid, the lower inner angle of the trapezoid may increase gradually or stepwise from the core side toward the outer peripheral side. As the radius of the electrode assembly increases, the radius of curvature increases. If the lower inner angle θ of the segment piece 61 increases as the radius of the electrode assembly increases, when the segment piece 61 is bent, the stress generated in the radial direction and the circumferential direction can be relaxed. Also, if the lower inner angle θ increases, when the segment piece 61 is bent, the area overlapping with the inner segment piece 61 and the number of overlapping layers both increase, so that the welding strength can be ensured uniformly in the radial direction and the circumferential direction, and the bent surface region can be formed flat.

[0128] The width d of the first part B1 B1 is designed such that when the segment piece 61 of the third part B2 is bent toward the core side, the core of the electrode assembly is opened to the outside by 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more based on its diameter.

[0129] In one example, the width of each segment group may be designed to constitute the same winding turn of the electrode assembly. Here, the winding turns can be counted relative to the end of the first portion B1 in the wound state of the electrode 60.

[0130] In other modifications, the width of each segment group may be designed to constitute at least one winding turn of the electrode assembly.

[0131] In further variations, the width and / or height and / or spacing of the sections 61 belonging to the same section group may increase or decrease gradually and / or stepwise and / or irregularly within the group or between adjacent groups.

[0132] When there is only one subsection group, the height of the subsection 61 in the third part B2 may be uniform.

[0133] The segmentation structure of the third part B2 can be extended to the second part B3. In this case, the second part B3, like the third part B2, may also contain multiple segments. Preferably, the segmentation structure of the second part B3 may be substantially identical to the outermost group of segments in the third part B2. In this case, the segments included in the second part B3 and the third part B2 may have substantially the same width, height, and spacing pitch. As a variation, the segments of the second part B3 may have a larger width and / or height and / or spacing pitch than those of the third part B2.

[0134] The structure of the electrode 60 described above can be applied to at least one of the first and second electrodes of opposite polarity included in an electrode assembly having a jelly roll structure. Furthermore, if the electrode structure of the embodiment (modified form) is applied to one of the first and second electrodes, a conventional electrode structure may be applied to the other. In addition, the electrode structure applied to the first electrode and the electrode structure applied to the second electrode do not have to be the same and may be different.

[0135] For example, when the first electrode and the second electrode are the positive and negative electrodes, one of the embodiments (modified forms) may be applied to the first electrode, and a conventional electrode structure (see Figure 1) may be applied to the second electrode.

[0136] As another example, when the first electrode and the second electrode are the positive and negative electrodes, one of the embodiments (modified forms) may be selectively applied to the first electrode, and the other embodiment (modified form) may be selectively applied to the second electrode.

[0137] In embodiments of the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode can be any active material known in the industry without limitation.

[0138] For example, the positive electrode active material is a material with the general chemical formula A[A x M y ]O 2+z The compound may contain alkali metal compounds represented as follows: (A contains at least one element from Li, Na, and K; M contains at least one element selected from Ni, Co, Mn, Ca, Mg, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, -0.1≦z≦2; stoichiometric coefficients x, y, z are selected so that the compound maintains electrical neutrality).

[0139] As another example, the positive electrode active material is an alkali metal compound xLiM disclosed in U.S. Patent No. 6,677,082, U.S. Patent No. 6,680,143, etc. 1 O2-(1-x)Li2M 2 O3(M 1 It contains at least one element having an average oxidation state of 3; M 2 It may contain at least one element having an average oxidation state of 4 (0 ≤ x ≤ 1).

[0140] As yet another example, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1-x M2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, and Al; M 2 contains 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 contains a halogen group element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, z are selected so that the compound maintains electrical neutrality), or it can be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Mg, and Al].

[0141] Preferably, the positive electrode active material may contain primary particles and / or secondary particles aggregated from primary particles.

[0142] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.

[0143] As the separation membrane, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., can be used alone or by laminating these. As another example, the separation membrane can use a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc.

[0144] The separation membrane may include a coating layer of inorganic particles on at least one surface. Alternatively, the separation membrane itself may consist of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that an interstitial volume exists between adjacent particles.

[0145] The structure of the electrode assembly according to an embodiment of the present invention will be described in detail below.

[0146] Figure 11 is a cross-sectional view of a jelly roll-type electrode assembly 100, in which the electrodes 60 of the embodiment are applied as the first electrode (positive electrode) and the second electrode (negative electrode), cut along the winding axis direction (Y axis).

[0147] Referring to Figure 11, the plain portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 100, a second portion B3 adjacent to the outer circumferential surface of the electrode assembly 100, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0148] The height of the plain portion of the first part B1 is lower than the segment 61 and the folded end segment 61' included in the third part B2. Therefore, when the segment 61 and the folded end segment 61' included in the third part B2 are folded, the plain portion of the first part B1 is not folded.

[0149] In the third section B2, the bend length H of the segment 61 or end-fold segment 61 closest to the core 102 is the same as or shorter than the radial length R of the first section B1. Therefore, even if the segment 61 and end-fold segment 61 included in the third section B2 are bent, the core 102 remains open to the outside. If the core 102 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. In addition, the welding process of the current collector plate can be easily carried out by inserting a welding jig through the core 102.

[0150] The length of the second section B3 may be shorter than the length of the first section B1. The height of the plain section of the second section B3 is lower than the segment 61 and the end bent segment 61' included in the third section B2. Therefore, it is possible to prevent the phenomenon of an internal short circuit occurring when the beading section of the battery housing comes into contact with the upper edge of the electrode assembly 100 during the process in which the beading section of the second section B3 is pressed near the winding turn. The plain section of the second section B3 is not bent when the segment 61 and the end bent segment 61' included in the third section B2 are bent.

[0151] The second blank portion 43b has the same structure as the first blank portion 43a. In one modified form, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0152] Multiple sub-sections 61 and multiple end-folded sub-sections 61' included in the third portion B2 of the first plain portion 43a and the second plain portion 43b can be folded toward the core 102 side of the electrode assembly 100 to form a folded surface region (F in Figure 10a). When the folded surface region F is formed, the end-folded sub-sections 61' are interposed between adjacent sub-sections 61 in the radial direction of the electrode assembly 100, and the folded end 61a forms a gap (G in Figure 10c), thereby providing an electrolyte impregnation path.

[0153] The electrode assembly according to the embodiment of the present invention is applicable to a jelly roll-type cylindrical battery.

[0154] Preferably, the cylindrical battery may be a cylindrical battery with a form factor ratio (defined as the ratio of the diameter to the height of the cylindrical battery, i.e., the ratio of height (H) to relative diameter (Φ)) greater than approximately 0.4. Here, the form factor refers to the values ​​indicating the diameter and height of the cylindrical battery.

[0155] The diameter of the cylindrical battery may be 35 mm or more, preferably 40 mm to 50 mm. The height of the cylindrical battery may be 70 mm or more, preferably 75 mm to 90 mm. A cylindrical battery according to one embodiment may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the numerical value indicating the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0156] When an electrode assembly with a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the stress applied radially when bending the plain section is large, making the plain section prone to tearing. Furthermore, when welding a current collector to the bent surface region of the plain section, the number of layers of the plain section in the bent surface region must be sufficiently increased in order to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode and electrode assembly according to an embodiment (modified form) of the present invention.

[0157] A battery according to one embodiment of the present invention may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0158] A battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0159] Furthermore, another embodiment of the battery may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

[0160] Furthermore, a battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0161] Furthermore, a battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0162] The present invention is not limited by the form factor ratio, diameter, and height of the cylindrical battery as described above. Therefore, the present invention can also be applied to batteries with a form factor ratio of about 0.4 or less, such as 1865 batteries, 2170 batteries, and the like.

[0163] The following describes in detail a cylindrical battery according to an embodiment of the present invention.

[0164] Figure 12 is a cross-sectional view of a cylindrical battery 190 according to an embodiment of the present invention, cut along the winding axis (Y axis).

[0165] Referring to Figure 12, the cylindrical battery 190 according to an embodiment of the present invention includes an electrode assembly 110 including a first electrode, a separator membrane, and a second electrode; a battery housing 142 housing the electrode assembly 110; and a seal 143 sealing the open end of the battery housing 142.

[0166] The battery housing 142 is a cylindrical container with an opening formed at the top. The battery housing 142 is made of a conductive metallic material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery housing 142. The battery housing 142 houses the electrode assembly 110 in its inner space through the upper opening, and also houses the electrolyte together with it.

[0167] Electrolytes are, A + B - It can be a salt with a structure like this. Here, A + Li + na + , K +It contains alkali metal cations such as, or ions consisting of combinations thereof. And, B - is, F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - ClO4 - AlO4 - AlCl4 - PF6 - SbF6 - AsF6 - BF2C2O4 - BC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - , C4F9SO3 - CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - , (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - It contains one or more anions selected from the group consisting of the following.

[0168] Furthermore, electrolytes may be used after being dissolved in an organic solvent. Suitable organic solvents 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 mixtures thereof.

[0169] The electrode assembly 110 may have a jelly roll structure. The electrode assembly 110 can be manufactured by winding up a laminate formed by stacking a lower separation membrane, a first electrode, an upper separation membrane, and a second electrode in sequence at least once, as shown in Figure 2.

[0170] The first electrode and the second electrode have different polarities. That is, if one has positive polarity, the other has negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the embodiment (modified form) described above. The other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (modified form). The electrode assembly 110 is not limited to one electrode pair, but may have two or more.

[0171] The electrode assembly 110 may include bent surface regions (F in Figure 10a) at its upper and lower ends. The first current collector plate 144 may be welded to the bent surface region F of the first blank portion 146a, and the second current collector plate 145 may be welded to the bent surface region F of the second blank portion 146b.

[0172] Preferably, 50% or more of the welding area W of the first current collector plate 144 and the second current collector plate 145 may overlap with the uniform layer number section of the bent surface area F (S2 in Figure 10c). Optionally, the remaining area of ​​the welding area W may overlap with the increasing layer number section of the bent surface area F (S1 in Figure 10c). It is preferable for the entire welding area W to overlap with the uniform layer number section (S2 in Figure 10c) in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separation film and active material layer.

[0173] The core 112 of the electrode assembly 110 is not blocked by the bent surface region F. Therefore, the electrolyte injection process is not hindered, and the welding process between the second current collector plate 145 and the battery housing 142 can be easily performed by inserting a welding jig through the core 112.

[0174] When the width and / or height and / or spacing pitch of the segmental sections are adjusted to satisfy the numerical range of the embodiment described above, as shown in Figure 10c, when the segmental sections are bent, at least 10 segments overlap to a degree that sufficient welding strength can be ensured, and no gaps are formed in the bent surface region F.

[0175] The sealing body 143 may include a cap plate 143a, a first gasket 143b that provides airtightness and insulation between the cap plate 143a and the battery housing 142, and a connecting plate 143c that is electrically and mechanically coupled to the cap plate 143a.

[0176] The cap plate 143a is a component made of a conductive metallic material and covers the upper opening of the battery housing 142. The cap plate 143a is electrically connected to the bent surface region F of the first electrode and is electrically insulated from the battery housing 142 via the first gasket 143b. Thus, the cap plate 143a can function as the first electrode terminal (e.g., positive electrode) of the cylindrical battery 190.

[0177] The cap plate 143a is placed on a beading portion 147 formed in the battery housing 142 and secured by a crimping portion 148. A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap plate 143a. The cap plate 143a may have a projection 143d extending upward from its center.

[0178] The battery housing 142 is electrically connected to the bent surface region F of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has negative polarity, then the battery housing 142 also has negative polarity.

[0179] The battery housing 142 is provided with a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by inward-pressing around the outer circumferential surface of the battery housing 142. The beading portion 147 prevents the electrode assembly 110 housed inside the battery housing 142 from coming out of the upper end opening of the battery housing 142 and can function as a support portion on which the seal 143 is placed.

[0180] The second portion B3 of the first electrode does not contain a segment, and the plain portion of the second portion B3 is lower in height than the third portion B2. Therefore, when the battery housing 142 is pushed in from the outside to form the beading portion 147, the winding turns of the second portion B3 are not substantially affected. Thus, the winding turns of the second portion B3 are not compressed by other components such as the beading portion 147, thereby preventing partial deformation of the electrode assembly 110 and preventing internal short circuits in the cylindrical battery 190.

[0181] Preferably, if the indentation depth of the beading portion 147 is D1 and the radial length from the inner circumferential surface of the battery housing 142 to the boundary point between the second portion B3 and the third portion B2 is D2, then the relation "D1 ≤ D2" may be satisfied. In this case, when the battery housing 142 is pressed in to form the beading portion 147, damage to the winding turns formed by the second portion B3 is substantially prevented.

[0182] The crimping portion 148 is formed on the upper part of the beading portion 147. The crimping portion 148 has a shape that extends and bends to enclose the outer circumferential surface of the cap plate 143a, which is positioned on the beading portion 147, and a portion of the upper surface of the cap plate 143a.

[0183] The cylindrical battery 190 may further include a first current collector plate 144 and / or a second current collector plate 145 and / or an insulator 146.

[0184] The first current collector plate 144 is coupled to the upper part of the electrode assembly 110. The first current collector plate 144 is made of a conductive metallic material such as aluminum, copper, steel, or nickel, and is electrically connected to the bent surface region F of the first electrode. The electrical connection may be made by welding. A lead 149 may be connected to the first current collector plate 144. The lead 149 may extend above the electrode assembly 110 and be coupled to the connecting plate 143c, or it may be directly coupled to the lower surface of the cap plate 143a. The lead 149 may be coupled to other parts by welding.

[0185] Preferably, the first current collector plate 144 can be formed integrally with the lead 149. In this case, the lead 149 may have a long plate shape extending outward from the center or near the periphery of the first current collector plate 144.

[0186] The bonding between the first current collector plate 144 and the bent surface region F of the first electrode can be performed, for example, by laser welding. Laser welding can be performed in a manner that partially melts the base material of the current collector plate. In a modified example, welding between the first current collector plate 144 and the bent surface region F can be performed with solder interposed. In this case, the solder may have a lower melting point than the first current collector plate 144 and the first blank portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, spot welding, etc.

[0187] A second current collector plate 145 may be attached to the lower surface of the electrode assembly 110. One side of the second current collector plate 145 may be attached to the bent surface region F of the second electrode by welding, and the other side may be attached to the inner bottom surface of the battery housing 142 by welding. The connection structure between the second current collector plate 145 and the bent surface region F of the second electrode may be substantially the same as the connection structure between the first current collector plate 144 and the bent surface region F of the first electrode.

[0188] The insulator 146 can cover the first current collector plate 144. By covering the upper surface of the first current collector plate 144 with the insulator 146, direct contact between the first current collector plate 144 and the inner circumferential surface of the battery housing 142 can be prevented.

[0189] The insulator 146 is provided with a lead hole 151 through which a lead 149 extending upward from the first current collector plate 144 is drawn out. The lead 149 is drawn out upward through the lead hole 151 and coupled to the lower surface of the connecting plate 143c or the lower surface of the cap plate 143a.

[0190] The peripheral region of the insulator 146 is interposed between the first current collector plate 144 and the beading portion 147, and can fix the connection between the electrode assembly 110 and the first current collector plate 144. As a result, the connection between the electrode assembly 110 and the first current collector plate 144 restricts the vertical movement of the cylindrical battery 190, thereby improving the assembly stability of the cylindrical battery 190.

[0191] The insulator 146 may consist of an insulating polymer resin. For example, the insulator 146 may consist of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0192] The battery housing 142 may further include a vent portion 152 formed on its lower surface. The vent portion 152 corresponds to an area on the lower surface of the battery housing 142 that is thinner than the surrounding area. The vent portion 152 is structurally weaker than the surrounding area. Therefore, if an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a certain level, the vent portion 152 may rupture, and the gas generated inside the battery housing 142 may be discharged to the outside. The internal pressure at which the vent portion 152 ruptures is approximately 15 kgf / cm². 2 ~35 kgf / cm² 2 It is possible.

[0193] The vent portion 152 may be formed continuously or discontinuously in a circular pattern on the lower surface of the battery housing 142. As a variation, the vent portion 152 may be formed in a linear pattern or other patterns.

[0194] Figure 13 is a cross-sectional view of a cylindrical battery 200 according to another embodiment of the present invention, cut along the winding axis (Y axis).

[0195] Referring to Figure 13, the cylindrical battery 200 differs from the cylindrical battery 190 in Figure 12 in that the structure of the electrode assembly is substantially the same, and other structural changes have been made excluding the electrode assembly.

[0196] Specifically, the cylindrical battery 200 includes a battery housing 171 through which rivet terminals 172 are driven. The rivet terminals 172 are installed through through holes formed in the closed end of the battery housing 171. The rivet terminals 172 are riveted into the through holes in the battery housing 171 with a second gasket 173 made of an insulating material interposed between them. The rivet terminals 172 are exposed outward in the direction opposite to the direction of gravity.

[0197] 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 end of the battery housing 171. The terminal exposure portion 172a may be located approximately in the center of the closed end of the battery housing 171. The maximum diameter of the terminal exposure portion 172a may be formed to be larger than the maximum diameter of the through hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate approximately in the center of the closed end of the battery housing 171 and be electrically connected to the first blank portion 146a of the first electrode. The bottom periphery of the terminal insertion portion 172b may be riveted onto the inner surface of the battery housing 171. That is, the bottom periphery of the terminal insertion portion 172b may have a curved shape toward the inner surface of the battery housing 171. A flat portion 172c is included inside the bottom periphery of the terminal insertion portion 172b. The maximum diameter of the bottom of the riveted terminal insertion section 172b may be even larger than the maximum diameter of the through-hole in the battery housing 171.

[0198] The flat portion 172c of the terminal insertion portion 172b can be welded to the central portion of the first current collector plate 144 connected to the bent surface region F of the first electrode. Laser welding is preferred as the welding method, but other welding methods such as ultrasonic welding can be used as alternatives.

[0199] An insulator 174 made of an insulating material may be interposed between the first current collector plate 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper part of the first current collector plate 144 and the upper peripheral portion of the electrode assembly 110. This prevents the second portion B3 of the electrode assembly 110 from coming into contact with the inner surface of the battery housing 171, which has opposite polarity, and causing a short circuit.

[0200] The thickness of the insulator 174 corresponds to or slightly greater than the distance between the upper surface of the first current collector plate 144 and the inner surface of the closed end of the battery housing 171. Thus, the insulator 174 can come into contact with the upper surface of the first current collector plate 144 and the inner surface of the closed end of the battery housing 171.

[0201] The terminal insertion portion 172b of the rivet terminal 172 can be welded to the first current collector plate 144 through a through hole in the insulator 174. The diameter of the through hole formed in the insulator 174 may be larger than the diameter of the rivet portion at the bottom of the terminal insertion portion 172b. Preferably, the through hole may expose the bottom of the terminal insertion portion 172b and the second gasket 173.

[0202] The second gasket 173 is interposed between the battery housing 171 and the rivet terminal 172, preventing electrical contact between the battery housing 171 and the rivet terminal 172, which have opposite polarities. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as the second electrode terminal (e.g., the negative electrode) of the cylindrical battery 200.

[0203] The second gasket 173 includes a gasket exposed portion 173a and a gasket inserted portion 173b. The gasket exposed portion 173a is interposed between the terminal exposed portion 172a of the rivet terminal 172 and the battery housing 171. The gasket inserted portion 173b is interposed between the terminal inserted portion 172b of the rivet terminal 172 and the battery housing 171. The gasket inserted portion 173b can be deformed together with the terminal inserted portion 172b during reveting to make close contact with the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0204] The gasket exposed portion 173a of the second gasket 173 may have a shape that extends to cover the outer circumferential surface of the terminal exposed portion 172a of the rivet terminal 172. When the second gasket 173 covers the outer circumferential surface of the rivet terminal 172, it is possible to prevent short circuits from occurring during the process of connecting electrical connection components such as busbars to the upper surface of the battery housing 171 and / or the rivet terminal 172. Although not shown, the gasket exposed portion 173a may have a shape that extends to cover not only the outer circumferential surface of the terminal exposed portion 172a but also a part of the upper surface.

[0205] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be bonded to the battery housing 171 and the rivet terminal 172 by heat fusion. In this case, the airtightness at the bonding interface between the second gasket 173 and the rivet terminal 172 and the bonding interface between the second gasket 173 and the battery housing 171 is enhanced. On the other hand, when the gasket exposed portion 173a of the second gasket 173 extends to the upper surface of the terminal exposed portion 172a, the rivet terminal 172 may be integrally bonded to the second gasket 173 by insert injection molding.

[0206] On the upper surface of the battery housing 171, the area 175 other than the area occupied by the rivet terminal 172 and the second gasket 173 corresponds to the second electrode terminal having opposite polarity to the rivet terminal 172.

[0207] The second current collector plate 176 is coupled to the lower part of the electrode assembly 110. The second current collector plate 176 is made of a conductive metallic material such as aluminum, steel, copper, or nickel, and is electrically connected to the bent surface region F of the second electrode.

[0208] Preferably, the second current collector plate 176 is electrically connected to the battery housing 171. Therefore, the second current collector plate 176 can be fixed by interposing at least a portion of its peripheral edge between the inner surface of the battery housing 171 and the first gasket 178b. As an example, at least a portion of the peripheral edge of the second current collector plate 176 can be fixed to the beading portion 180 formed at the lower end of the battery housing 171 by welding, while being supported by the lower end surface of the beading portion 180. In a modified example, at least a portion of the peripheral edge of the second current collector plate 176 can be directly welded to the inner wall surface of the battery housing 171.

[0209] Preferably, the second current collector plate 176 and the bent surface region F of the second electrode can be joined, for example, by laser welding. The welded portion between the second current collector plate 176 and the bent surface region F can be separated by a predetermined distance toward the core C with respect to the inner circumferential surface of the beading portion 180.

[0210] The seal 178 that seals the lower open end of the battery housing 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap plate 178a from the battery housing 171. The crimping portion 181 fixes the periphery of the cap plate 178a and the first gasket 178b together. The cap plate 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as that of the above-described embodiment (modified form). The lower surface of the cap plate 178a may be located above the lower end of the crimping portion 181. In this case, a space is formed below the cap plate 178a, allowing for smooth venting. This is particularly useful when a cylindrical battery 200 is installed so that the crimping portion 181 faces in the direction of gravity.

[0211] Preferably, the cap plate 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap plate 178a and the battery housing 171, the cap plate 178a does not have electrical polarity. The seal 178 mainly serves to seal the open end at the bottom of the battery housing 171 and to release gas when the internal pressure of the cylindrical battery 200 increases above a critical value. The critical value of the internal pressure is 15 kgf / cm². 2 ~35 kgf / cm² 2 That is the case.

[0212] On the other hand, in the modified version, the battery housing 171 does not have to include the beading portion 180 and the crimping portion 181. In this case, the side wall of the battery housing 171 may extend in a straight line, and the periphery of the cap plate 178a may be directly connected to the open end of the battery housing 171. The periphery of the cap plate 178a may be welded to the open end of the battery housing 171. In such a modified version, the first gasket 178b may be omitted.

[0213] In one modified example, at least a portion of the second current collector plate 176, for example, its peripheral edge, can be connected to the cap plate 178a.

[0214] In other modifications, at least a portion of the second current collector plate 176, for example, a peripheral portion, is bent so as to face the inner surface of the side wall of the battery housing 171, and the bent portion may be joined to the inner surface of the side wall of the battery housing 171 by welding.

[0215] In further variations, the periphery of the cap plate 178a, the open end of the battery housing 171, and the peripheral portion of the second current collector plate 176 can be integrally joined by welding.

[0216] In further modifications, the inner region of the periphery of the cap plate 178a can be directly welded to the bent surface region F of the second electrode. In this case, the second current collector plate 176 can be omitted because the cap plate 178a serves to electrically connect the second electrode and the battery housing 171.

[0217] Preferably, the rivet terminal 172 electrically connected to the bent surface region F of the first electrode is used as the first electrode terminal. In addition, the portion 175 of the upper surface of the battery housing 171, excluding the rivet terminal 172, which is electrically connected to the bent surface region F of the second electrode through the second current collector plate 176, is used as the second electrode terminal with opposite polarity to the first electrode terminal. In this way, when the two electrode terminals are located on the top of the cylindrical battery 200, it is possible to arrange electrical connection components such as busbars on only one side of the cylindrical battery 200. This can lead to a simplification of the battery pack structure and an improvement in energy density. Furthermore, since the portion 175 used as the second electrode terminal has a substantially flattened shape, it is possible to secure a sufficient contact area for joining electrical connection components such as busbars. As a result, the cylindrical battery 200 can reduce the resistance at the joint of the electrical connection components to a desirable level.

[0218] The cylindrical batteries mentioned above are used in the manufacture of battery packs.

[0219] Figure 14 is a schematic diagram showing the configuration of a battery pack according to an embodiment of the present invention.

[0220] Referring to Figure 14, the battery pack 300 according to an embodiment of the present invention includes an assembly to which cylindrical batteries 301 are electrically connected, and a pack housing 302 that houses the assembly. The cylindrical battery 301 may be any one of the batteries according to the embodiments (modified forms) described above. For convenience of illustration, components such as busbars, cooling units, and external terminals for the electrical connection of the cylindrical battery 301 are not shown.

[0221] The battery pack 300 may be installed in an automobile. The automobile may, for example, be an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The automobile may include four-wheeled vehicles or two-wheeled vehicles.

[0222] Figure 15 is a diagram illustrating an automobile including the battery pack 300 shown in Figure 14.

[0223] Referring to Figure 15, the automobile V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The automobile V operates by receiving power from the battery pack 300 according to an embodiment of the present invention.

[0224] According to embodiments of the present invention, the structure of the end portion of the segment can be improved to form gaps in the radial and / or circumferential directions in the bent surface region formed by bending the segment, which are used as pathways for electrolyte impregnation, thereby shortening the electrolyte impregnation time.

[0225] According to another embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly so that the electrode assembly and the inner circumferential surface of the battery housing do not interfere with each other during the formation process of the beading portion of the battery housing, it is possible to prevent internal short circuits in the cylindrical battery due to partial deformation of the electrode assembly.

[0226] According to yet another embodiment of the present invention, by applying a structure in which a current collector plate is welded over a wide area to a bent surface region formed by bending a segment, an electrode assembly with improved energy density and reduced resistance can be provided.

[0227] According to yet another embodiment of the present invention, the structure of the plain portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the plain portion is bent, thereby facilitating the electrolyte injection process and the welding process between the battery housing (or rivet terminal) and the current collector plate.

[0228] According to yet another embodiment of the present invention, it is possible to provide a cylindrical battery having a structure in which electrolyte impregnation is improved, internal resistance is low, internal short circuits are prevented, and the welding strength between the current collector plate and the blank portion is improved, a battery pack including the cylindrical battery, and an automobile.

[0229] As described above, the present invention has been explained with limited embodiments and drawings, but it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention belongs. [Explanation of symbols]

[0230] 10 positive electrode 10a Positive electrode blank area 11 Negative electrode 11a Negative electrode blank area 12 Separation membrane 20 Current collector 21 Active material 22 Plain section 30 Current collector 31 Current collector 33 cores 41 Current collector 42 Active material layer 43 Plain section 43a First blank section 43b 2nd plain area 44 Insulating coating layer 60 electrodes 61 End fold section 61' End fold section 61a Bent end 62 center 63 Cutting groove 100 electrode assembly 102 cores 110 Electrode assembly 112 cores 142 Battery Housing 143 Sealed body 143a Cap plate 143b First Gasket 143c Connecting Plate 143d Protrusion 144 First current collector plate 145 Second current collector plate 146 Insulator 146a First blank section 146b Second blank section 147 Beading section 148 Crimping section 149 Reed 151 lead holes 152 Vent section 171 Battery Housing 172 Rivet terminals 172a Exposed terminal part 172b Terminal insertion section 172c flat area 173 Second Gasket 173a Exposed gasket portion 173b Gasket insertion section 174 Insulator 175 area, part 176 Second current collector plate 178 Sealed body 178a Cap plate 178b First Gasket 179 Bend section 180 Beading section 181 Crimping section 190 Cylindrical Battery 200 Cylindrical Battery 300 Battery Pack 301 Cylindrical Battery 302 Pack Housing B1 Core side plain area B2 Plain section in the middle B3 Plain outer edge C Core E electrolyte F bend surface area G Gap H Fold length JR electrode assembly S1 Stack Count Increase Interval S2 Uniform Layer Stacking Section

Claims

1. An electrode assembly comprising a first electrode, a second electrode, and a separation membrane interposed between the first and second electrodes, which are wound around a single axis to define a core and an outer surface, At least one of the first electrode and the second electrode includes a plain portion extending in the winding direction along the long edge end, The plain portion includes a plurality of segments that are separated by cutting grooves formed along the winding direction and can be folded independently. The plurality of segments are bent toward the core to form a bent surface region at one end of the electrode assembly. An electrode assembly in which at least some of the plurality of segments include a bent end.

2. When a segment containing the aforementioned bent end is defined as an end-bent segment, the bent surface region includes a plurality of end-bent segments, The electrode assembly according to claim 1, wherein when the number of plain areas intersecting a hypothetical straight line passing through the center of the bent end is defined as the number of bends of the bent end, the bent end has two or more bends and forms gaps between adjacent segments in the radial direction of the electrode assembly.

3. The electrode assembly according to claim 2, wherein the gap has a separation distance between adjacent segments in the radial direction of the electrode assembly that corresponds to the thickness of the bent end.

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

5. The electrode assembly according to claim 2, wherein the bent surface region includes a radial section in which the number of end bent segments arranged in the circumferential direction increases stepwise or gradually from the core toward the outer surface.

6. The electrode assembly according to claim 2, wherein the bent surface region includes a radius section in which the number of bends of the bent end increases stepwise or gradually from the core toward the outer circumferential surface.

7. The electrode assembly according to claim 2, wherein the bent surface region includes a radius section in which the number of bends of the bent end is maintained the same from the core to the outer peripheral surface.

8. The height of the aforementioned multiple end-bent segments increases in stages from the core of the electrode assembly toward the outer surface. The electrode assembly according to claim 2, wherein the bent surface region includes a radial section in which the number of bends at the bent end increases as the height of the end bend section increases.

9. The electrode assembly according to claim 2, wherein the bent surface region includes a radial section in which the uniaxial width of the plain portion forming the bent end increases stepwise or gradually from the core of the electrode assembly toward the outer circumferential surface.

10. When the number of blank areas at any point in the folded surface region that intersect with a virtual line passing through the folded surface region parallel to the uniaxial direction is defined as the number of blank layer stacks at that point, The aforementioned bent surface region includes a section with increasing number of layers and a section with a uniform number of layers, extending from the outer peripheral surface of the electrode assembly towards the core. The electrode assembly according to claim 2, wherein the number of end-folded segments included in the uniform-layer-number-number-section section is even greater than the number of end-folded segments included in the increased-layer-number-number-section section.

11. When the number of blank areas at any point in the folded surface region that intersect with a virtual line passing through the folded surface region parallel to the uniaxial direction is defined as the number of blank layer stacks at that point, The aforementioned bent surface region includes a section with increasing number of layers and a section with a uniform number of layers, extending from the outer peripheral surface of the electrode assembly towards the core. The electrode assembly according to claim 2, wherein the number of folds of the folded end included in the uniform number of layers is even greater than the number of folds of the folded end included in the increased number of layers section.

12. The electrode assembly according to claim 1, wherein the bent end has a structure that is folded in a jelly roll shape, a structure that is folded in a zigzag shape, or a structure that is folded randomly.

13. An electrode assembly according to any one of claims 1 to 12, A battery housing including an open end and a closed end, through which the electrode assembly is housed and electrically connected to the second electrode of the electrode assembly, A sealing body that seals the open end of the battery housing, A cylindrical battery comprising a terminal electrically connected to a first electrode of the electrode assembly and having its surface exposed on the outside of the battery housing.

14. The aforementioned bent surface region is formed by bending a plurality of subsections contained within the plain portion of the first electrode. The cylindrical battery according to claim 13, further comprising a first current collector plate that electrically connects the bent surface region and the terminal.

15. The terminal is mounted in a through hole formed in the closed end of the battery housing so as to be insulated from the battery housing. The terminal includes a terminal exposure portion exposed to the outside of the closed end, and a terminal insertion portion extending from the terminal exposure portion and inserted into the inside of the battery housing through the through hole. The cylindrical battery according to claim 13, wherein the periphery of the bottom of the terminal insertion portion is riveted toward the inner surface of the closed end.

16. The sealing body includes a cap plate that seals the open end of the battery housing. The cylindrical battery according to claim 13, wherein the terminal is the cap plate.

17. The aforementioned bent surface region is formed by bending a plurality of subsections contained within the plain portion of the second electrode. The cylindrical battery according to claim 13, further comprising a second current collector plate that electrically connects the bent surface region and the side wall of the battery housing.

18. The sealing body includes a cap plate that covers the open end of the battery housing, and a gasket interposed between the periphery of the cap plate and the open end. The cylindrical battery according to claim 17, wherein the periphery of the second current collector plate is interposed between the gasket and the side wall of the battery housing.

19. The battery housing includes a beading portion formed by pressing the outer circumferential surface near the open end, The cylindrical battery according to claim 18, wherein the periphery of the cap plate is in contact with the beading portion.

20. The sealing body includes a cap plate that covers the open end of the battery housing, The cylindrical battery according to claim 13, wherein the periphery of the cap plate is connected to the open end.

21. The cylindrical battery according to claim 20, wherein at least a portion of the cap plate is coupled to the bent surface region of the electrode assembly.

22. A battery pack comprising a plurality of cylindrical batteries as described in claim 13.

23. An automobile comprising the battery pack described in claim 22.

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