Cylindrical battery with reduced resistance

Abstract

The present invention relates to an electrode assembly in which a first electrode (positive electrode) has a tab structure and a second electrode (negative electrode) has a tabless structure, and a cylindrical battery including the electrode assembly. The first electrode 2 has a tab structure, and the second electrode 4 has a tabless structure. That is, a first electrode tab 23 protrudes from one axial side of the electrode assembly 1, and a second electrode uncoated portion 41 is exposed from the other axial side. The electrode assembly 1 is accommodated in a battery can 6, and the first electrode tab 23 is electrically connected to a cover 63 of the battery can 6, and the second electrode uncoated portion 41 is electrically connected to the battery can 6. At this time, the axial length of the first electrode 2 is shorter than the axial length of the second electrode 4, and the distance between the first electrode 2 and one axial end of the second electrode 4 is shorter than the distance between the other axial end of the first electrode 2 and the uncoated portions 21, 41 starting from the second electrode 4. The first electrode tab 23 can be insulated only at a portion where interference with the second electrode 4 may occur.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0169768 dated December 1, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a cylindrical battery including a jelly-roll type electrode assembly, and more particularly to a cylindrical battery structure in which the positive electrode and the negative electrode have different tab and tabless structures, respectively. [Background technology]

[0003] Secondary batteries, which are highly applicable to a wide range of products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources.

[0004] These secondary batteries have not only the primary advantage of dramatically reducing the use of fossil fuels, but also the advantage of not producing any by-products from the use of energy, and are therefore attracting attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0005] Currently, widely used types of secondary batteries include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of these unit secondary battery cells, i.e., unit battery cells 100, is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack may be configured by connecting multiple battery cells in series. Alternatively, a battery pack may be configured by connecting multiple battery cells 100 in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number and electrical connection form of the battery cells included in the battery pack can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, known types of unit secondary battery cells include cylindrical, prismatic, and pouch-type battery cells. In the case of a cylindrical battery cell, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the separator is wound up to form a jelly-roll-type electrode assembly. This jelly-roll-type electrode assembly is then inserted into a battery can to form a battery. Strip-shaped electrode tabs may be connected to the uncoated portions of the positive and negative electrodes, electrically connecting the electrode assembly to electrode terminals exposed to the outside. For reference, the positive electrode terminal is a cap plate of a sealing body that seals the opening of the battery can, and the negative electrode terminal is the battery can. However, conventional cylindrical battery cells having such a structure have problems such as high resistance, excessive heat generation, and poor current collection efficiency due to current concentration at the strip-shaped electrode tabs connected to the positive and / or negative uncoated portions.

[0007] Resistance and heat generation are not major issues for small cylindrical battery cells with the 18650 form factor. However, if the internal resistance of a large-capacity cylindrical battery cell is high, a large amount of heat can be generated around the electrode tabs during fast charging, which can cause the cylindrical battery cell to catch fire.

[0008] Various attempts have been made to solve this problem. Representative examples include increasing the number of electrode tabs to multiple locations to widen the current path, and shortening the current path by positioning the electrode tabs closer to the center of the electrode relative to the position before winding. These methods can reduce electrical resistance because electrical resistance is inversely proportional to the area of ​​the path through which current flows and proportional to its length.

[0009] 3 is a cross-sectional view of a cylindrical battery including a jelly-roll type electrode assembly with a tab structure. In both the positive electrode 2 and the negative electrode 4, current is connected to the battery can lid 63 or the battery can 6 only via a positive electrode tab 23 or a negative electrode tab 43 provided in one or more locations on each positive electrode 2 and negative electrode 4. In this case, the area of ​​the current path is narrow and the resistance is high.

[0010] 1 and 2 show the state of a positive electrode and a negative electrode constituting a jelly roll electrode assembly having a tab structure before being wound. Referring to these drawings, the positive electrode 2 is shorter than the negative electrode 4, and two positive electrode tabs 23 are located in the middle of the positive electrode 2. In contrast, the negative electrode 4 is wound radially outward relative to the positive electrode 2 and is longer than the positive electrode 2, so the negative electrode tabs 43 can only be located at both ends due to the manufacturing process. Therefore, while the resistance of the positive electrode 2 can be significantly reduced by reducing the length of the current path, other methods of reducing resistance are particularly needed for the negative electrode 4.

[0011] Another method devised to reduce resistance is a jelly roll battery with a tabless structure that does not use electrode tabs. Figure 4 is a cross-sectional view of a cylindrical battery including a jelly roll-type electrode assembly with a tabless structure. Referring to this figure, a positive electrode uncoated region 21, which is not coated with an active material, protrudes from one axial side of the positive electrode 2, and a negative electrode uncoated region 41, which is not coated with an active material, protrudes from the other axial side of the negative electrode 4. Each uncoated region 21, 41 is welded to the current collector plate 5, and collectively functions as an electrode tab. This increases the area of ​​the current path and significantly reduces resistance. Each uncoated region 21, 41 can be bent radially to form a flat surface to improve welding characteristics with the current collector plate 5.

[0012] However, the above-described tabless structure is likely to cause a short circuit between the negative and positive electrodes during the process of welding the uncoated portions 21, 41 to the current collector plate 5 or during the process of bending the uncoated portions 21, 41 to improve welding characteristics. Also, the tabless structure requires an additional insulating layer 65 to insulate the positive current collector plate from the battery can, and the axial length of the battery can is increased by the thickness of the positive uncoated portion 21 and the current collector plate 5, which inevitably reduces battery capacity.

[0013] Meanwhile, the thickness of the portion of the jelly roll-type electrode assembly where the tabs are connected is thicker than the portion where the tabs are not connected. As a result, the radius of the jelly roll where the tabs are located in the circumferential direction of the electrode assembly wound into a jelly roll is larger than the radius of the jelly roll where the tabs are not located. Due to this difference in radius, the portion where the tabs are located receives more pressure in the radial direction than the other portions during repeated charging and discharging of the cell, which causes the hollow portion of the core to collapse or the attached layers to peel off more quickly, resulting in more rapid deterioration. Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention has been devised in light of the background of the prior art as described above, and aims to provide a jelly-roll type electrode assembly that can reduce the resistance of the second electrode, where there is a limit to how much resistance can be reduced by simply improving the tab structure of both electrodes, and a cylindrical battery structure including the same.

[0015] Meanwhile, an object of the present invention is to provide an economical electrode assembly that improves space utilization and increases capacity by simplifying the structure and manufacturing process as much as possible, and a cylindrical battery structure including the same.

[0016] Yet another technical object of the present invention is to provide an electrode assembly that can minimize the possibility of a short circuit occurring between a first electrode and a second electrode without introducing excessive insulation treatment, and a cylindrical battery structure including the same.

[0017] The present invention also provides an electrode assembly that can minimize the phenomenon of cell deterioration due to the thickness of the tabs when using one or more tabs to reduce resistance, and a cylindrical battery structure including the same.

[0018] Another object of the present invention is to provide a battery pack including the improved cylindrical battery cell, and a vehicle including the battery pack.

[0019] The technical object of the present invention is not limited to the above-mentioned objects, and other unmentioned objects and advantages of the present invention can be understood from the following description and can be more clearly understood from the examples of the present invention. Furthermore, it is clear that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0020] In order to achieve the above object, the present invention provides a jelly roll-type electrode assembly having a structure in which an electrode stack including first electrodes, second electrodes, and a separator is wound up, and the first electrodes and second electrodes are alternately stacked in both radial directions with the separator interposed therebetween. The first electrode has a first electrode uncoated portion that is not coated with an active material, and a first electrode tab electrically connected to the first electrode uncoated portion protrudes from one axial end of the electrode assembly. The second electrode has a second electrode uncoated portion that is not coated with an active material and serves as a tab at the other axial end.

[0021] The first electrode uncoated portion may be provided in a region corresponding to a region coated with the active material in the axial direction.

[0022] The first electrode uncoated portion may be provided in a form that further extends axially outward from an axial end of the region coated with the active material.

[0023] The first electrode uncoated portion may be provided over the entire length or a part of the length.

[0024] The first electrode uncoated portion and the first electrode tab may be provided in one or more.

[0025] The plurality of first electrode tabs may overlap each other to form a single electrically connected tab.

[0026] The one first electrode tab may be connected to the first electrode at a position avoiding both ends of the first electrode in the winding direction.

[0027] The two or more first electrode tabs may be connected to the first electrode at positions avoiding both ends and a center portion of the first electrode in a winding direction.

[0028] When only one first electrode tab is provided, in order to prevent an increase in resistance due to an increase in the current path, when the first electrode is divided along the width direction so as to be divided into three equal parts in the winding direction, the first electrode tab can be electrically connected to the first electrode at a position that avoids both end sections in the winding direction.

[0029] When only two first electrode tabs are provided, in order to prevent an increase in resistance due to an increase in the current path, when the first electrode is divided along the width direction into four equal parts in the winding direction, one first electrode tab may be located in each of two central regions, avoiding both end regions in the winding direction, and electrically connected to the first electrode. When three or more first electrode tabs are provided, they may be arranged in a similar manner to reduce the current path.

[0030] Depending on the arrangement of the first electrode tabs, the plurality of first electrode tabs may be arranged at different radial positions in the radial direction.

[0031] In an electrode assembly in which the plurality of first electrode tabs are connected to regions corresponding to regions coated with the active material in the axial direction, the circumferential positions at which the plurality of first electrode tabs are arranged may be arranged so as not to overlap each other.

[0032] In an electrode assembly in which the plurality of first electrode tabs are connected to a first electrode uncoated portion that extends further axially outward from an axial end of the active material-coated region, the circumferential positions at which the plurality of first electrode tabs are arranged may be arranged to overlap each other.

[0033] The first electrode tab may be connected to the first electrode at an appropriate position so that they can be easily connected to each other when the electrode stack is wound up.

[0034] The second electrode uncoated portion may be provided in a continuous shape from the other axial end of the second electrode in the winding direction, or may be provided in a notched shape intermittently in the winding direction.

[0035] The second electrode uncoated portion may have an axially protruding height that increases continuously or intermittently.

[0036] The second electrode uncoated portion may be bent in the radial direction to improve welding performance with the current collector plate or the bottom surface of the battery can, which will be described later.

[0037] A current collecting plate may be attached to the second electrode uncoated portion. For example, the current collecting plate may be attached to the surface of the second electrode uncoated portion bent in the radial direction by welding.

[0038] The second electrode and the separation membrane may have an axial length greater than that of the first electrode.

[0039] An axial end portion of the first electrode may be positioned lower than an axial end portion of the second electrode.

[0040] A distance between one axial end of each of the first electrode and the second electrode may be shorter than a distance between the other axial end of the first electrode and a point where an uncoated portion of the second electrode begins.

[0041] The present invention also provides a cylindrical battery structure including the electrode assembly.

[0042] The cylindrical battery may include a cylindrical battery can having one axial side open. The electrode assembly may be housed in the battery can such that the second electrode uncoated portion faces a bottom surface of the battery can, and the second electrode uncoated portion may be electrically connected to the bottom surface of the battery can. The first electrode tab may be electrically connected to a battery can lid (cap) that covers an upper portion of the battery can.

[0043] A beading portion may be provided on the side wall of the battery can, the beading portion extending radially inwardly from the side wall of the battery can between one axial end of the electrode assembly and the battery can lid.

[0044] An insulating layer may be provided at the first electrode tab portion to insulate the first electrode tab from the battery can and the second electrode.

[0045] The insulating layer may cover one axial side of the electrode assembly, and the first electrode may pass through the insulating layer to be connected to the battery can lid.

[0046] The insulating layer may be provided in a portion of the first electrode tab adjacent to the second electrode.

[0047] The above-mentioned problems can also be solved by a battery pack including the cylindrical battery cell, and a vehicle including the battery pack. These battery packs and vehicles are already known to those skilled in the art, and therefore will not be described further in this specification. [Effects of the Invention]

[0048] The present invention provides a jelly-roll type electrode assembly structure that reduces resistance by applying a tabless structure to the second electrode, where there is a limit to how much resistance can be reduced by improving the tab structure alone.

[0049] From another aspect, the present invention applies an improved tab structure to the first electrode, which can sufficiently reduce resistance through an improved tab structure. This prevents a reduction in space utilization and a complicated manufacturing process, which would be caused by the need to insulate the first electrode uncoated portion and the current collector plate welded thereto when a tabless structure is applied, due to the additional thickness of the first electrode uncoated portion and the current collector plate from the battery can and the second electrode.

[0050] In the present invention, one or more tabs used to reduce resistance are axially connected to a plain portion at an end of the tab that is outside the active material coating region. Therefore, even if the number of tabs is increased, the tabs are not interposed in the active material-coated retention region, preventing deterioration due to uneven thickness of the tabs.

[0051] In the present invention, two or more tabs applied to reduce resistance are arranged in circumferentially corresponding positions when the tabs are axially connected to the plain portion provided at the end outside the active material coating region, thereby making assembly processes such as welding the tabs together and connecting them to the lid very convenient.

[0052] In the present invention, even when two or more tabs used to reduce resistance are axially connected to uncoated portions provided in areas corresponding to active material coating areas, the tabs are arranged in positions that do not overlap each other in the circumferential direction, thereby minimizing the phenomenon of deterioration caused by uneven thickness of the tabs.

[0053] The present invention also provides an electrode assembly structure with improved stability that can block short circuits between the first and second electrodes at both axial ends without the need for excessive insulation treatment when the tabless structure is also applied to the first electrode.

[0054] The present invention can provide an improved cylindrical battery cell including the improved electrode assembly, a battery pack including the battery cell, and a vehicle including the battery pack.

[0055] In addition, the present invention can have several different effects, which will be explained in each embodiment, or the explanation of effects that can be easily inferred by ordinary engineers will be omitted. [Brief explanation of the drawings]

[0056] [Figure 1] 1 is a view showing an electrode stack in a state before being wound into a jelly roll to form an electrode assembly; [Figure 2] FIG. 2 is a development view showing a state before the first electrode and the second electrode of the tab structure are wound up. [Figure 3] FIG. 1 is a cross-sectional view of a cylindrical battery including an electrode assembly with a tab structure. [Figure 4] FIG. 1 is a cross-sectional view of a cylindrical battery including an electrode assembly with a tabless structure. [Figure 5] 10 is a development view showing a state before being wound up of a first electrode and a second electrode according to an embodiment of the present invention, in which a continuous non-coating portion is provided at the other axial end of the second electrode. FIG. [Figure 6] 10 is a development view showing a state before being wound up of a first electrode and a second electrode according to an embodiment of the present invention, in which an uncoated portion having a discontinuous cutout shape is provided at the other axial end of the second electrode. FIG. [Figure 7] 1 is a cross-sectional view of an electrode assembly according to an embodiment of the present invention, in which a first electrode is connected to a second electrode and a non-coating portion is provided on a second electrode that protrudes and bends toward the other axial direction. [Figure 8] FIG. 7 shows an electrode assembly according to an embodiment of the present invention, in which a current collecting plate is connected to the bent second electrode uncoated portion. [Figure 9] 3 is an enlarged cross-sectional view showing an electrode assembly according to an embodiment of the present invention, in which the axial length of a first electrode is shorter than the axial length of a second electrode. [Figure 10] FIG. 9 is an enlarged cross-sectional view showing an electrode assembly according to an embodiment of the present invention, in which the distance between one axial end of the active material coated region of the first electrode and the second electrode is shorter than the distance between the other axial end. [Figure 11] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention, in which one axial side of an electrode assembly is covered with an insulating layer. [Figure 12] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention, in which only a portion of a first electrode tab is covered with an insulating layer. [Figure 15] FIG. 10 is a development view of another embodiment of the first electrode and the second electrode. [Figure 16] FIG. 10 is a development view of another embodiment of the first electrode and the second electrode. [Figure 17] FIG. 10 is a development view of another embodiment of the first electrode and the second electrode. [Figure 18] FIG. 18 is a perspective view of a jelly roll type electrode assembly including the first electrode and the second electrode of FIGS. 15 to 17 and wound up. [Figure 19] FIG. 19 is a side cross-sectional view of FIG. 18. [Figure 20] 10 is another example of the second electrode. [Figure 21] 21 is an enlarged cross-sectional view of a laminated structure using the second electrode of FIG. 20. [Figure 22] 1 is a perspective view showing a battery pack including a cylindrical battery cell according to the present invention; [Figure 23] FIG. 23 is a perspective view showing a vehicle including the battery pack of FIG. 22. DETAILED DESCRIPTION OF THE INVENTION

[0057] The above-mentioned objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily implement the technical concept of the present invention. In describing the present invention, if a detailed description of known technologies relating to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0058] Although terms such as "first" and "second" are used to describe various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a first component may also be a second component.

[0059] Unless otherwise specified in the entire specification, each element may be singular or plural.

[0060] Hereinafter, when an arbitrary structure is arranged "on top (or bottom)" of a component or "above (or below)" a component, it means that the arbitrary structure is not only arranged in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure arranged above (or below) the component.

[0061] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0062] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. Terms such as "comprise" or "include" in this application should not be interpreted as including all of the multiple components or multiple steps described in the specification, but should be interpreted as meaning that some of the components or some of the steps may not be included, or may include additional components or steps.

[0063] Throughout the specification, unless otherwise specified, "A and / or B" means A, B or A and B, and "C to D" means C or more and D or less.

[0064] For ease 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). The direction surrounding the winding shaft is referred to as the circumferential direction (X). The direction toward or away from the winding shaft is referred to as the radial direction (Z). Of these, the direction toward the winding shaft is particularly referred to as the centripetal direction, and the direction away from the winding shaft is particularly referred to as the centrifugal direction.

[0065] The present invention provides a jelly roll electrode assembly structure that can reduce resistance, improve space utilization, and prevent short circuits, and a cylindrical battery cell structure including the electrode assembly.

[0066] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

[0067] First, the structures and manufacturing methods of cylindrical batteries with tab and tabless structures will be described. Generally, cylindrical batteries are manufactured by incorporating an electrode assembly wound in a jelly roll shape inside a battery can.

[0068] FIG. 1 shows an electrode stack before being wound into a jelly roll to form an electrode assembly. Referring to this figure, the jelly roll-type electrode assembly can be formed by winding an electrode stack in which roll sheets of a first electrode 2, a separator 3, a second electrode 4, and a separator 3 are sequentially stacked. As a result, the jelly roll-type electrode assembly has a circular pipe shape with a hollow portion formed in the winding shaft. That is, the longitudinal direction (X) of the electrode stack corresponds to the winding direction of the cylindrical electrode assembly, i.e., the circumferential direction, the width direction (Y) of the electrode stack corresponds to the axial direction of the electrode assembly, and the normal direction (Z) of the electrode stack corresponds to the radial direction (centripetal direction or centrifugal direction) of the electrode assembly.

[0069] The separator may be made of the same material and have the same shape regardless of the stacking position. The separator may be made of a material and have a structure that insulates the first electrode 2 and the second electrode 4 in the electrode stack so as to prevent an electrical short circuit between the two electrodes, while allowing the electrolyte described below to pass through.

[0070] The separator includes a porous polymer substrate and porous coating layers disposed on both sides of the porous polymer substrate, the coating layers including inorganic particles and a binder polymer.

[0071] The porous polymer substrate may be a polyolefin-based porous substrate.

[0072] The polyolefin porous substrate may be in the form of a film or non-woven web. The porous structure facilitates smooth movement of the electrolyte between the positive and negative electrodes, improves the electrolyte impregnation of the substrate itself, and ensures excellent ionic conductivity. This prevents an increase in the internal resistance of the electrochemical device, thereby preventing a decrease in the performance of the electrochemical device.

[0073] The polyolefin porous substrate used in the present invention can be any planar porous substrate commonly used in electrochemical devices, and its material and shape can be selected from a variety of options depending on the intended purpose.

[0074] The polyolefin porous substrate may be, but is not limited to, a film or non-woven web formed from high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or a mixture of two or more of these.

[0075] The polyolefin porous substrate may have a thickness of 8 to 30 μm, but this is merely an example, and a thickness outside this range may be adopted in consideration of mechanical properties and high-rate charge / discharge characteristics of the battery.

[0076] The nonwoven fabric sheet according to the present invention may be made of polyethylene (PE), polypropylene (PP), or a mixture of two or more of these. For example, the nonwoven fabric sheet may be manufactured by fiber radiating. For example, the nonwoven fabric sheet may be manufactured by melt-blown, where fibers of the material are radiated at or above their melting points.

[0077] The nonwoven fabric sheet may have an elongation ratio of 200 to 400%, more preferably 300 to 400%. If the elongation ratio is less than 200%, the probability of contact between electrodes increases when a nail penetrates, while if it is more than 400%, the area around the nail penetration point also elongates, making the separator thinner and reducing barrier properties.

[0078] The nonwoven fabric sheet has a plurality of pores with an average diameter of 0.1 to 10 μm formed therein. If the pore size is smaller than 0.1 μm, smooth movement of lithium ions and / or the electrolyte solution does not occur, and if the pore size is larger than 10 μm, the effect of the present invention, which is to prevent contact between the positive electrode and the negative electrode by stretching the nonwoven fabric sheet when a nail is penetrated, is difficult to achieve.

[0079] The nonwoven fabric sheet may have a porosity of 40 to 70%. If the porosity is less than 40%, smooth movement of lithium ions and / or electrolyte is hindered, while if the porosity is greater than 70%, the effect of the present invention, which aims to prevent contact between the positive and negative electrodes by stretching the nonwoven fabric sheet when a nail is penetrated, is difficult to achieve. The nonwoven fabric sheet manufactured in this manner may have an air permeability of 1 to 20 seconds / 100 mL.

[0080] Furthermore, the nonwoven fabric sheet may have a thickness of 10 to 20 μm, but this is merely an example and is not intended to be limiting. Depending on the permeability of the nonwoven fabric sheet, a nonwoven fabric sheet with a thickness outside the above range may also be used.

[0081] The nonwoven fabric sheet can be bonded to the separation membrane component placed below the nonwoven fabric sheet by lamination. The lamination can be performed at a temperature ranging from 100 to 150°C. If the lamination is performed at a temperature lower than 100°C, the lamination effect is lost, and if the lamination is performed at a temperature higher than 150°C, part of the nonwoven fabric will melt.

[0082] The separation membrane according to one embodiment of the present invention, which is laminated under the above conditions, has improved resistance to nail penetration when compared to separation membranes made of conventional nonwoven fabric sheets and when compared to separation membranes in which a layer containing inorganic particles is formed on at least one surface of a film or nonwoven fabric sheet.

[0083] The inorganic particles in the porous coating layer are bound to each other by the binder polymer while being in contact with each other and charged with electricity, thereby forming interstitial volumes between the inorganic particles, which become empty spaces and can form pores.

[0084] The inorganic particles used to form the porous coating layer are inorganic particles, i.e., particles within the operating voltage range of the electrochemical device (e.g., Li / Li + Inorganic particles that do not undergo oxidation and / or reduction reactions at a voltage (0 to 5 V relative to the reference voltage) can be further added. In particular, when inorganic particles with ion transfer ability are used, the ionic conductivity in the electrochemical device can be increased, thereby improving performance. Furthermore, when inorganic particles with a high dielectric constant are used as the inorganic particles, they can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution.

[0085] For the reasons mentioned above, the inorganic particles preferably include high-dielectric-constant inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having lithium ion transfer ability, or a mixture thereof.

[0086] Non-limiting examples of inorganic particles with a dielectric constant of 5 or greater include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg 1 / 3 Nb 2 / 3)O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC, or mixtures thereof.

[0087] In particular, the aforementioned BaTiO3, Pb(Zr,Ti)O3 (PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg 1 / 3 Nb 2 / 3 Inorganic particles such as )O3-PbTiO3 (PMN-PT) and hafnia (HfO2) not only exhibit high dielectric constant characteristics with a dielectric constant of 100 or more, but also possess piezoelectricity, which generates electric charges when stretched or compressed under a certain pressure, creating a potential difference between the two surfaces. This prevents internal short circuits between the electrodes due to external impacts, thereby improving the safety of electrochemical devices. Furthermore, when the above-mentioned high dielectric constant inorganic particles are mixed with inorganic particles having lithium ion transport ability, these improved effects can be multiplied.

[0088] Inorganic particles with lithium ion transport ability refer to inorganic particles that contain lithium element but do not store lithium but have the function of transporting lithium ions. Inorganic particles with lithium ion transport ability can transport and transport lithium ions due to a type of defect present inside the particle structure, thereby improving the lithium ion conductivity in the battery and thereby improving the battery performance. Non-limiting examples of inorganic particles with lithium ion transport ability include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3,0 <x<2、0<y<3)、リチウムアルミニウムチタンホスフェート(Li x Al y Ti z(PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) such as 14Li2O - 9Al2O3 - 38TiO2 - 39P2O5 x O y series glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 lithium germanium thiophosphate (Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li x N y , 0 < x < 4, 0 < y < 2), SiS2 series glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5 series glass (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7), or mixtures thereof, etc.

[0089] Although there is no limit to the size of the inorganic particles in the porous coating layer, for the formation of a coating layer with a uniform thickness and an appropriate porosity, it is preferably 0.001 - 10 μm. If it is less than 0.001 μm, the dispersibility of the inorganic particles may decrease. If it exceeds 10 μm, the thickness of the porous coating layer increases, the mechanical properties may decrease, and due to the size of the pores being too large, the probability of internal short - circuit occurring during battery charge and discharge increases.

[0090] ]>Binder polymers that form the porous coating layer include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. The binder polymer may be any one selected from the group consisting of cellulose acetate, cellulose acetate ester, cellulose acetate copolymer ...

[0091] The composition ratio of inorganic particles to binder polymer used in the porous coating layer is preferably, for example, in the range of 50:50 to 99:1, more preferably 70:30 to 95:5. If the ratio of inorganic particles to binder polymer is less than 50:50, the binder polymer content will be too high, which may reduce the improvement in the thermal stability of the separator. Furthermore, the pore size and porosity will decrease due to the reduction in void space formed between the inorganic particles, ultimately resulting in a decrease in battery performance. If the inorganic particle content exceeds 99 parts by weight, the binder polymer content will be too low, which may weaken the peel resistance of the porous coating layer. The thickness of the porous coating layer is not particularly limited, but is preferably in the range of 0.01 to 20 μm. The pore size and porosity are also not particularly limited, but the pore size is preferably in the range of 0.001 to 10 μm, and the porosity is preferably in the range of 10 to 90%. The pore size and porosity depend primarily on the size of the inorganic particles. For example, when inorganic particles with a particle size of 1 μm or less are used, the pores formed will also be approximately 1 μm or less. These pore structures are subsequently filled with the electrolyte, and the filled electrolyte serves to transport ions. If the pore size and porosity are less than 0.001 μm and 10%, respectively, the material may function as a resistance layer. However, if the pore size and porosity are greater than 10 μm and 90%, respectively, the mechanical properties may be degraded.

[0092] The porous coating layer can be formed by dissolving or dispersing a binder polymer in a dispersion medium, adding inorganic particles to obtain a slurry for forming the porous coating layer, and then coating and drying the slurry on at least one surface of a substrate. The dispersion medium preferably has a solubility index similar to that of the binder polymer to be used and a low boiling point. This allows for uniform mixing and easy subsequent removal of the dispersion medium. Non-limiting examples of usable dispersion mediums include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof.

[0093] It is preferable to add inorganic particles to a dispersion in which the binder polymer is dispersed in a dispersion medium, and then crush the inorganic particles. In this case, the crushing time is appropriately 1 to 20 hours, and the particle size of the crushed inorganic particles is preferably 0.001 to 10 μm, as described above. As a crushing method, a conventional method can be used, and a ball mill method is particularly preferable.

[0094] The binder polymer dispersion liquid containing the dispersed inorganic particles is then coated onto at least one surface of a porous polymer substrate under a humidity condition of 10 to 80% and dried. The dispersion liquid can be coated onto the porous polymer substrate using a conventional coating method known in the art, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0095] The porous coating layer may further include other additives such as a conductive agent in addition to the inorganic particles and binder polymer described above.

[0096] The final separator according to the present invention may have a thickness of 1 to 100 μm or 5 to 50 μm. If the thickness is less than 1 μm, the separator may not function properly and mechanical properties may deteriorate, while if the thickness is more than 100 μm, battery properties may deteriorate during high-rate charge / discharge. The separator may also have a porosity of 40 to 60% and an air permeability of 150 to 300 seconds / 100 mL.

[0097] According to an embodiment of the present invention, the porous polymer substrate may be polyethylene or polypropylene-based, and the inorganic particles in the porous coating layer may be aluminum oxide or silicon oxide-based coating materials.

[0098] When using a separator according to an embodiment of the present invention, porous coating layers are provided on both sides of a porous polymer substrate, thereby forming a uniform solid electrolyte interfacial layer that improves electrolyte impregnation performance and ensuring superior air permeability compared to conventional single-sided inorganic-coated separators. For example, the air permeability may be within 120 s / 100 cc. Furthermore, even when inorganic porous coating layers are provided on both sides, the thickness can be the same as that of conventional single-sided inorganic-coated separators. For example, the thickness may be within 15.0 μm.

[0099] Furthermore, when a separator according to an embodiment of the present invention is used, the safety of the separator is improved and heat resistance and compression resistance can be ensured. Specifically, heat resistance with a thermal shrinkage of 5% or less at 180°C can be ensured, and a puncture strength of 550 gf or more can be ensured. This prevents damage or puncture of the separator at the step when core deformation occurs during cycling of a battery using such a separator.

[0100] The first electrode 2 may be a positive electrode and the second electrode 4 may be a negative electrode, but the reverse may also be true, and so they will be referred to herein as the first electrode and the second electrode.

[0101] The first electrode 2 can be wound more inward than the second electrode 4. As a result, the first electrode 2 can have a shorter radius from the winding shaft than the second electrode 4, and therefore a shorter circumferential length along the winding direction. In this case, the first electrode 2 before winding can have a shorter length in the longitudinal direction than the second electrode 4 before winding.

[0102] 2 is an exploded view showing the state of the tab-structured first and second electrodes before being wound up. Referring to this figure, each of the first electrode 2 and the second electrode 4 may be coated on one or both sides with an active material 22, 42. The active material 22, 42 is coated on the surface of the first electrode 2 and the second electrode 4 and participates in the electrode reaction by storing or releasing ions.

[0103] In the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be any active material known in the art.

[0104] The positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2x Lithium manganese oxides (LiMnO2), such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides, such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M xO2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x=0.01 to 0.3); 2-x M x Lithium manganese composite oxides expressed as LiMnO2 (where M=Co, Ni, Fe, Cr, Zn, or Ta, and x=0.01 to 0.1) or Li2Mn3MO8 (where M=Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the lithium in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3; or composite oxides formed by a combination of these, which contain a lithium intercalation material as the main component, include, but are not limited to, the above-mentioned types.

[0105] The positive electrode current collector has a thickness of, for example, 3 to 500 μm. There are no particular limitations on the positive electrode current collector, as long as it does not cause chemical changes in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, plastic carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like can be used. The electrode current collector can have fine irregularities formed on its surface to increase the adhesive strength of the positive electrode active material, and can be in various forms, such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0106] A conductive material can be further mixed with the positive electrode active material particles. The conductive material is added, for example, in an amount of 1 to 50 wt % based on the total weight of the mixture containing the positive electrode active material. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0107] The negative electrode is fabricated by coating negative electrode active material particles on a negative electrode current collector and drying the coating, and may further include components such as the aforementioned conductive material, binder, and solvent, if necessary.

[0108] The negative electrode current collector has a thickness of, for example, 3 to 500 μm. There are no particular limitations on the negative electrode current collector, so long as it does not cause chemical changes in the battery and is conductive. For example, copper, stainless steel, aluminum, nickel, titanium, plastic carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium, silver, or the like, and aluminum-cadmium alloys can be used. Furthermore, like the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the binding force of the negative electrode active material, and the negative electrode current collector can be used in various forms, such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0109] The negative electrode active material may be, for example, carbon such as non-graphitizable carbon or graphite-based carbon; Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-x Me'yO zMetal composite oxides of (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0110] The binder polymer usable in the electrode is a component that aids in binding between the electrode active material particles and the conductive material, etc., and between the electrode current collector, and is added in an amount of, for example, 1 to 50 wt % based on the total weight of the mixture including the electrode active material. Examples of these binder polymers include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. The binder polymer may be any one selected from the group consisting of cellulose acetate, cellulose acetate ester, cellulose acetate copolymer ...

[0111] Non-limiting examples of solvents used in the manufacture of the electrode include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. These solvents provide an appropriate level of viscosity so that a slurry coating layer can be formed at a desired level on the surface of the electrode current collector.

[0112] The negative electrode comprises a current collector; and a negative electrode active material layer located on at least one surface of the current collector and including a negative electrode active material, a binder polymer, and a conductive material, the negative electrode active material layer comprising a lower layer region in contact with the current collector and an upper layer region in contact with the lower layer region and extending to the surface of the negative electrode active material layer, and the lower layer region and the upper layer region each independently contain at least one of graphite and a silicon-based compound as the negative electrode active material.

[0113] The lower layer region may contain natural graphite as the negative electrode active material, and the upper layer region may contain artificial graphite as the negative electrode active material.

[0114] The lower layer region and the upper layer region may each independently further include a silicon-based compound as a negative electrode active material.

[0115] The silicon-based compound is SiO x (0≦x≦2) and SiC.

[0116] According to an embodiment of the present invention, the negative electrode may be manufactured by coating a lower layer slurry containing a lower layer negative electrode active material on a current collector and drying the slurry to form a lower layer region, and then coating an upper layer slurry containing an upper layer negative electrode active material on the lower layer region and drying the slurry to form an upper layer region.

[0117] According to one embodiment of the present invention, the negative electrode may be prepared by preparing a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material; coating one surface of a negative electrode current collector with the lower layer slurry, and simultaneously or after a predetermined time, coating the upper layer slurry on the lower layer slurry; and and drying the coated lower layer slurry and upper layer slurry simultaneously to form an active material layer.

[0118] In the latter method, a mixed region (intermixing) of different active materials may exist at the interface between the lower and upper layers of the negative electrode. This is because, when an active material layer is formed by simultaneously or sequentially coating a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material onto a current collector and then simultaneously drying them, a predetermined mixed region is formed at the interface where the lower layer slurry and the upper layer slurry contact each other before drying, and then this mixed region is formed into a layer shape during drying.

[0119] In the negative electrode active material layer according to an embodiment of the present invention, the weight ratio (or the ratio of the load amount per unit area) of the upper layer region to the lower layer region may be 20:80 to 50:50, specifically 25:75 to 50:50.

[0120] The thicknesses of the lower and upper regions of the negative electrode active material layer of the present invention may not be completely equal to the thicknesses of the coated lower layer slurry and the coated upper layer slurry, but the thickness ratio of the lower and upper regions of the negative electrode active material layer of the present invention finally obtained after the drying or selective rolling process may be equal to the thickness ratio of the coated lower layer slurry and the coated upper layer slurry.

[0121] The first slurry is coated, and the second slurry is coated on the first slurry simultaneously or after a predetermined time interval. According to one embodiment of the present invention, the predetermined time difference may be 0.6 seconds or less, or 0.02 to 0.6 seconds, or 0.02 to 0.06 seconds, or 0.02 to 0.03 seconds. Since the time difference between the coating of the first and second slurries is due to the coating equipment, it is more preferable to coat the first and second slurries simultaneously. The method of coating the second slurry on the first slurry can use an apparatus such as a double slot die.

[0122] The step of forming the active material layer may further include a step of rolling the active material layer after the drying step, wherein the rolling may be performed by a method commonly used in the art, such as roll pressing, at a pressure of 1 to 20 MPa and a temperature of 15 to 30°C.

[0123] The step of simultaneously drying the coated lower layer slurry and upper layer slurry to form an active material layer may be carried out by a method commonly used in the art using a combination of a hot air dryer and an infrared dryer.

[0124] The weight % of the first binder polymer in the solid content of the lower layer slurry may be the same as or greater than the weight % of the second binder polymer in the solid content of the upper layer slurry. According to one embodiment of the present invention, the weight % of the first binder polymer in the solid content of the lower layer slurry may be 1.0 to 4.2 times, 1.5 to 3.6 times, or 1.5 to 3 times greater than the weight % of the second binder polymer in the solid content of the upper layer slurry.

[0125] In this case, when the weight percentage of the first binder in the coated lower layer slurry and the weight percentage of the second binder in the coated upper layer slurry satisfy these ranges, the binder in the lower layer region is not too small, so detachment of the electrode layer does not occur, and the binder in the upper layer region is not too large, so the resistance of the upper layer of the electrode is reduced, which is advantageous for fast charging performance.

[0126] The weight percentage of the first binder polymer in the solid content of the lower layer slurry may be 2 to 30 weight percent, or 5 to 20 weight percent, or 5 to 20 weight percent, and the weight percentage of the second binder polymer in the solid content of the upper layer slurry may be 0.5 to 20 weight percent, or 1 to 15 weight percent, or 1 to 10 weight percent, or 2 to 5 weight percent.

[0127] The total proportion (wt %) of the first binder polymer and the second binder polymer in the total solid content of the lower layer slurry and the upper layer slurry may be 2 to 20 wt % or 5 to 15 wt %.

[0128] 2, the first electrode 2 and the second electrode 4 may have a first electrode uncoated region 21 and a second electrode uncoated region 41, respectively, that are not coated with the active materials 22 and 42. The first electrode uncoated region 21 and the second electrode uncoated region 41 may have a first electrode tab 23 and a second electrode tab 43, respectively, that are electrically connected to the first electrode uncoated region 21 and the second electrode uncoated region 41 in order to electrically connect the first electrode 2 and the second electrode 4 to the outside.

[0129] The first electrode tab 23 and the second electrode tab 43 may be provided one by one or in plural.

[0130] If the second electrode uncoated portion 41 and the second electrode tab 43 are only provided on both ends of the second electrode 4 due to the manufacturing process, the current path of the second electrode 4 becomes longer, and the resistance increases. This is especially true when the second electrode 4 is longer than the first electrode 2.

[0131] 3 is a cross-sectional view of a cylindrical battery including a tab-structured electrode assembly. Referring to this figure, an electrode assembly 1, in which an electrode laminate is wound into a jelly roll shape, is housed in a battery can 6, one axial side of which is open.

[0132] The first electrode tab 23 connected to the first electrode uncoated portion 21 of the electrode assembly 1 is connected to a first electrode terminal 631 provided on a battery can lid 63, thereby electrically connecting the first electrode 2 to the battery can lid 63 and the outside. One axial side of the electrode assembly 1 from which the first electrode tab 23 protrudes may be covered with an insulating layer 65.

[0133] The second electrode tab 43 connected to the second electrode uncoated portion 41 of the electrode assembly 1 is connected to the bottom surface 62 of the battery can, thereby electrically connecting the second electrode to the battery can 6 and the outside.

[0134] The battery can lid 63 is connected to the first electrode 2, and the battery can 6 is connected to the second electrode 4, so that an insulating layer 65 is provided between the battery can lid 63 and the battery can 6 to prevent short circuits.

[0135] The side wall 61 of the battery can may be provided with beading portions 64 extending radially inward on the electrode assembly 1. By providing these beading portions 64, the electrode assembly 1 can be stably accommodated in the battery can 6 without any gaps above or below.

[0136] In the above tab structure, the only current paths between the first electrode 2 and the second electrode 4 are the first electrode tab 23 and the second electrode tab 43, so the resistance in this portion is very high, heat may be generated, and performance and durability may be poor. This is because electrical resistance is proportional to the length of the current path and inversely proportional to the area, so a narrow current path is not conducive to reducing resistance.

[0137] 4 is a cross-sectional view of a cylindrical battery including a tabless-structured electrode assembly. Referring to this figure, the electrode assembly is constructed such that an electrode assembly 1 wound up in a jelly roll shape is housed in a battery can 6 that is open on one axial side.

[0138] A first electrode uncoated portion 21 and a second electrode uncoated portion 41 protrude from both axial sides of the electrode assembly 1, and the first electrode uncoated portion 21 and the second electrode uncoated portion 41 are respectively connected to the current collector plate 5. In this case, the first electrode uncoated portion 21 and the second electrode uncoated portion 41 may be bent in a radial direction to improve the bonding performance between the first electrode collector plate 51 and the second electrode collector plate 52.

[0139] The first electrode current collector plate 51 connected to the first electrode uncoated portion 21 is connected to a first electrode tab 23, and the first electrode tab 23 is connected to a battery can lid 63 via a first electrode terminal 631, thereby electrically connecting the first electrode to the outside.

[0140] The second electrode current collecting plate 52 connected to the second electrode uncoated portion 41 is connected to the bottom surface 62 of the battery can, thereby electrically connecting the second electrode to the battery can 6 and the outside.

[0141] The battery can lid 63 is connected to the first electrode 2, and the battery can 6 is connected to the second electrode 4. Therefore, an insulating layer 65 is provided between the battery can lid 63 and the battery can 6 to prevent a short circuit. In addition, to prevent a short circuit between the first electrode current collector 51 and the inner wall of the battery can 6, the top and side surfaces of the first electrode current collector 51 may be covered with the insulating layer 65.

[0142] The side wall 61 of the battery can may be provided with beading portions 64 extending radially inward on the electrode assembly 1. By providing these beading portions 64, the electrode assembly 1 can be stably accommodated in the battery can 6 without any vertical clearance.

[0143] The above-described tabless structure, for the second electrode, allows current to flow through the second electrode uncoated region 41, the second electrode current collector plate 52, and the bottom surface 62 of the battery can, creating a wide current path and reducing resistance. However, for the first electrode 2, current flows through the first electrode tab 23 anyway, so this structure is not useful for reducing resistance. Instead, the addition of the first electrode uncoated region 21, the first electrode current collector plate 51, and the insulating layer 65 requires the battery can 6 to be longer vertically. This results in a shorter length of the electrode assembly 1 and reduced capacity for cylindrical battery cells of the same specifications. Furthermore, if the first electrode uncoated region 21 and the second electrode uncoated region 41 are bent radially to improve bonding performance with the current collector plate 5, they may short-circuit with the axial ends of the second electrode 4 and the first electrode 2, respectively, and are less stable.

[0144] Meanwhile, a thermal runaway prevention mechanism (CID; Current Interrupt Device) and / or a vent structure may be applied to the cover 63. However, as described above, the structure in which the first electrode uncoated portion 21 is bent in the radial direction and the current collector plate 5 is welded onto it may prevent the internal pressure of the battery can 6 from fully acting on the CID or may cover the vent structure, thereby affecting battery performance.

[0145] Therefore, the present invention provides an improved electrode assembly structure that has the effect of reducing resistance and improving space utilization of a tabless structure on the second electrode side, and has the space utilization and stability against short circuits of a tab structure on the first electrode side, which sufficiently reduces resistance even without a tabless structure.

[0146] 5 and 6 are development views showing the first and second electrodes according to the respective embodiments of the present invention before being wound up, in which a continuous uncoated portion and a discontinuous uncoated portion are provided at the other axial end of the second electrode, respectively.

[0147] Referring to these drawings, both surfaces of a first electrode 2 and a second electrode 4 are coated with active materials 22 and 42. A first electrode uncoated region 21 is provided in a section in the longitudinal direction (X) of the first electrode 2 (the section coated with active material in the axial direction (Y)), and a first electrode tab 23 connected to the first electrode uncoated region 21 protrudes to one side in the width direction (axial direction after winding) of the first electrode 2. A second electrode uncoated region 41 is provided and exposed at the other end of the second electrode 4 in the width direction.

[0148] The first electrode uncoated portion 21 and the first electrode tab 23 may be provided singly or in plural. When a plurality of first electrode tabs 23 are provided, the current path of the first electrode 2 becomes wider, which may result in a reduction in resistance. As will be described later, the plurality of first electrode tabs 23 may be formed so that after winding, at least a portion of the area of ​​the first electrode tabs 23 overlaps with each other and is electrically connected to form a single tab. This structure makes it easier to connect the first electrode tab 23 to the cover 63.

[0149] The number of first electrode tabs 23 may be determined as the minimum number at which the resistance value measured in the path connected by the first electrode 2 can fall below a predetermined resistance value. For example, if the resistance value measured when using two first electrode tabs 23 is below a predetermined resistance value, it is sufficient to use two first electrode tabs 23, and it is not necessary to use three or more first electrode tabs 23.

[0150] The first electrode uncoated portion 21 and the first electrode tab 23 may be provided at appropriate positions to minimize the current path of the first electrode 2. For example, when one first electrode uncoated portion 21 and one first electrode tab 23 are provided, the first electrode uncoated portion 21 and the first electrode tab 23 may be provided at positions that avoid both longitudinal end regions when the first electrode 2 is divided along the width direction so as to be divided into three equal parts in the longitudinal direction (winding direction). Furthermore, when two first electrode uncoated portions 21 and two first electrode tabs 23 are provided, the first electrode uncoated portion 21 and the first electrode tab 23 may be provided at two longitudinal end regions when the first electrode 2 is divided along the width direction so as to be divided into four equal parts in the longitudinal direction (winding direction). When the first electrode uncoated portions 21 and the first electrode tabs 23 are provided at three or more locations, they can be appropriately arranged by a method similar to that described above.

[0151] Although the number of first electrode tabs 23 is minimized, if the resistance value measured by appropriately selecting the positions of the first electrode tabs 23 is higher than a predetermined resistance value, the number of first electrode tabs 23 can be minimized by increasing the number of first electrode tabs 23 by one and appropriately selecting the positions of the first electrode tabs 23.

[0152] The second electrode uncoated portion 41 may be provided at the other end of the second electrode in the width direction in a continuous form in the longitudinal direction as shown in Fig. 5, or may be provided in a form of discontinuous notches in the longitudinal direction as shown in Fig. 6. The notches may be provided for bending the second electrode uncoated portion 41, which will be described later.

[0153] The first electrode 2 and the second electrode 4 as described above may be stacked and wound with the separator 3 interposed therebetween to form a jelly roll type electrode assembly.

[0154] FIG. 7 is a cross-sectional view of an electrode assembly according to an embodiment of the present invention, in which a first electrode is connected to a first electrode and a second electrode is provided with an uncoated portion that protrudes and bends toward the other axial direction. FIG. 8 is an electrode assembly according to an embodiment of the present invention, in which a current collecting plate is connected to the bent uncoated portion of the second electrode in FIG. 7.

[0155] Referring to FIG. 7 , the second electrode uncoated region 41 may protrude toward the other axial direction of the electrode assembly 1 relative to the first electrode 2 and the separator 3. The second electrode uncoated region 41 may be bent in a radial direction. The radial direction includes both a centrifugal direction and a centripetal direction. More preferably, according to the embodiment, the second electrode uncoated region 41 may be bent in a centripetal direction. This allows the second electrode uncoated region 41 to provide a flat surface on the other axial direction, thereby improving bonding performance when bonding with the current collector plate 5 or the bottom surface 62 of the battery can, which will be described later. This also allows the current path to be further widened, thereby reducing resistance.

[0156] 8, the bent second electrode uncoated portion 41 may have a surface to which a current collector 5 is connected. When the electrode assembly 1 is housed in a battery can 6 (described later) and the second electrode uncoated portion 41 is electrically connected to a bottom surface 62 of the battery can 6, the presence of the current collector 5 may improve the stability of assembly and bonding.

[0157] Even when wound up, the first electrode tab 23 protrudes toward one axial direction relative to the second electrode 4 and the separator 3. When a plurality of first electrode tabs 23 are provided, they may overlap each other to form a single electrically connected tab, thereby widening the current path and reducing resistance.

[0158] 9 is an enlarged cross-sectional view of an electrode assembly according to an embodiment of the present invention, in which the axial length of the first electrode is shorter than the axial length of the second electrode. Referring to this figure, there is a possibility that the second electrode 4 and the first electrode 4 may short-circuit with each other, particularly when the second electrode uncoated portion 41 is bending. In a typical jelly roll electrode assembly, this short-circuit can be prevented by having the separator 3 protrude in both axial directions beyond the first electrode 2 and the second electrode 4. However, in a tableless structure such as the second electrode 4 according to an embodiment of the present invention, the second electrode uncoated portion 41 protrudes in the axial direction beyond the separator 3, making this difficult to prevent.

[0159] To solve the above-described short circuit problem, the first electrode 2 may be formed to have a shorter axial length than the second electrode 4. As a result, the other axial end of the first electrode 2 is positioned deeper within the separator 3, and the separator 3 insulates the second electrode uncoated portion 41 from the first electrode 2, thereby reducing the possibility of a short circuit.

[0160] 10 is an enlarged cross-sectional view showing an electrode assembly according to an embodiment of the present invention, in which the distance between one axial end of the active material-coated region of the first electrode and the second electrode shown in FIG. 9 is shorter than the distance between the other axial end. Referring to this, the distance between one axial end of the first electrode 2 and one axial end of the second electrode 4 may be shorter than the distance between the other axial end of the first electrode 2 and a position where the second electrode uncoated region 41 of the second electrode 4 begins.

[0161] This is because the tab structure of the first electrode 2 reduces the risk of short circuiting, unlike a tabless structure. The first electrode 2 is not bent or separately pressed, and the first electrode tab 23 is insulated, so the risk of short circuiting is significantly lower than when the second electrode uncoated portion 41 is bent. Therefore, the distance between the axial ends of the first electrode 2 and the second electrode 4 can be narrowed in the area where the first electrode tab 23 protrudes, thereby improving space utilization and increasing capacity.

[0162] In addition, to improve space utilization, the first electrode 2 may be formed so that its one axial end is aligned with or positioned more inward than the one axial end of the second electrode 4, i.e., its height is the same as or lower than the height of the one axial end of the second electrode 4. This is because, unlike the other axial end of the first electrode 2 being positioned relatively more inward than the other axial end of the second electrode 4 on the other axial side having the second electrode uncoated portion 41 to avoid short-circuiting with the second electrode 4, there is little need to form the one axial end of the second electrode 4 lower or further inward than the one axial end of the first electrode 2, but by not having the end of the first electrode 2 protrude toward the one axial side in this manner, space utilization can be improved and capacitance can be increased.

[0163] The electrode assembly according to one embodiment of the present invention is manufactured by winding an electrode stack, in which a first electrode 2, a separator 3, a second electrode 4, and another separator 3 are sequentially stacked, around a winding shaft in a winding direction (longitudinal direction). The first electrode 2 is a positive electrode, and the second electrode 4 is a negative electrode. When the first electrode 2 is divided along its width direction so as to be divided into four equal parts in the longitudinal direction, two regions are provided with first electrode uncoated portions 21, one of which is provided in each region, avoiding both longitudinal end regions. A first electrode tab 23 is electrically connected to each of the first electrode uncoated portions 21, and the first electrode tab 23 protrudes to one side in the width direction (axial direction). The second electrode 4 is longer than the first electrode 2, and the second electrode 4 is provided with second electrode uncoated portions 41 that are intermittently cut out in the longitudinal direction (winding direction) along the other end of the width direction. the second electrode uncoated portion 41 is exposed to the other widthwise side of the second electrode 4; a height of one widthwise end of the first electrode 2 in the electrode stack is the same as a height of one widthwise end of the second electrode; the other axial end of the second electrode 4 and the separator 3 extend and protrude relatively to the other axial side compared to the other axial end of the first electrode 2; the axial length of the first electrode 2 is shorter than the axial length of the second electrode 4, and the center thereof is located higher than the center of the second electrode 4; after being wound up, the first electrode tabs 23 protrude to one axial side of the electrode assembly 1 and overlap each other to form a single tab; the second electrode uncoated portion 41 is bent in a centripetal direction to form a flat surface; and a current collector plate 5 may be welded to the flat surface formed by the bent second electrode uncoated portion 41.

[0164] The present invention also provides a cylindrical battery cell structure including the improved electrode assembly.

[0165] FIG. 11 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention, in which one axial side of each electrode assembly is covered with an insulating layer, and FIG. 12 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention, in which only a portion of a first electrode tab is covered with an insulating layer.

[0166] 11 , a cylindrical battery according to one embodiment of the present invention includes a battery can 6 that is open on one side in the axial direction, and the electrode assembly 1 may be manufactured by being housed in the battery can 6 with the second electrode uncoated portion 41 facing the bottom surface 62 of the battery can 6. The second electrode uncoated portion 41 is electrically connected to the bottom surface 62 of the battery can, and a current collector 5 may be interposed between the second electrode uncoated portion 41 and the bottom surface 62 of the battery can. In this case, the second electrode uncoated portion 41 may be directly connected to the bottom surface 62 of the battery can without the current collector 5, thereby improving space utilization and increasing capacity.

[0167] A beading portion 64, which includes the side wall 61 of the battery can 6, is provided on one axial side of the battery can 6 containing the electrode assembly 1 in order to fix the electrode assembly 1 on the electrode assembly 1. A battery can lid is provided on the beading portion 64, which is fixed to the battery can 6 by a crimping method with an insulating layer 65 interposed therebetween, and covers the open portion of one axial side of the battery can 6.

[0168] The first electrode tab 23 may protrude from one axial side of the electrode assembly 1 and be connected to the battery can lid 63 via a first electrode terminal 631. The first electrode terminal 631 may be provided separately and electrically connected to the lid 63, or may be provided as a part of the lid 63, or the lid 63 itself may be the first electrode terminal 631.

[0169] A thermal runaway prevention mechanism (CID; Current Interrupt Device) and / or a vent structure may be applied to the cover 63. The cover 63 may be electrically connected to the first electrode terminal 631 through the thermal runaway prevention mechanism (CID; Current Interrupt Device) and / or the vent structure.

[0170] At this time, one axial side of the electrode assembly 1 may have the first electrode tab protruding and covered with an insulating layer 65 .

[0171] 12, the insulating layer 65 may be provided to cover the area between the battery can lid 63 and the battery can 6 as well as areas where the first electrode tab 23 may interfere with the second electrode 4, preferably to cover the boundary where the first electrode tab 23 protrudes from the jelly roll portion of the electrode assembly 1. This improves space utilization and increases capacity compared to a method of covering the entire side of the electrode assembly 1 as shown in FIG.

[0172] In a cylindrical battery cell according to an embodiment of the present invention, an electrode assembly 1 according to an embodiment of the present invention is accommodated in an open battery can 6 with a second electrode uncoated portion 41 facing downward, the second electrode uncoated portion 41 being electrically connected to a bottom surface 62 of the battery can 6, the first electrode tab being electrically connected to a battery can lid 63 covering an upper portion of the battery can 6 via a first electrode terminal 631 provided on the lid 63, and a portion of the first electrode tab 23 that may short-circuit with the second electrode 4 and a portion between the lid 63 and the battery can 6 may be covered with an insulating layer 65.

[0173] FIG. 13 illustrates a structure in which the second electrode uncoated portion 41 of the electrode assembly 1 is bent and overlapped and directly welded to the bottom surface 62 of the battery can 6, and two first electrode tabs 23 protrude in the axial direction at different radial positions and are welded to first electrode terminals 631.

[0174] The bottom surface 62 of the battery can 6 may have a structure that is slightly recessed from the lower end of the side wall 61 of the battery can 6. When such a recessed portion is welded to the second electrode uncoated portion 41, the welding may be performed by irradiating a laser onto the bottom surface of the bottom surface 62, and the recessed structure of the bottom surface 62 prevents the welded portion from coming into contact with the ground and causing damage.

[0175] The first electrode terminal 631 may have a vent 633 structure, such as a notch groove, that weakens the rigidity. Referring to Figure 13, in comparison with Figure 4, it can be seen that the active material is applied to the electrode assembly 1 up to the beading portion 64, thereby further increasing the energy density.

[0176] The insulating layer 65, which is crimped together with the lid 63, extends in the axial direction and covers the inner periphery around the beading portion. Furthermore, the inner periphery of the insulating layer 65 guides the electrode tabs 23 to gather radially inward, ensuring that the electrode tabs 23 do not come into contact with the side wall 61 of the battery can 6.

[0177] The cylindrical battery can 6 can be filled with an electrolyte for the battery reaction. + B - The salt may have the following structure: + Li + , Na + , K. + and alkali metal cations such as 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 - , CF3 - , CH3CO2 - , SCN - , and (CF3CF2SO2)2N - The anion comprises at least one anion selected from the group consisting of:

[0178] The electrolyte can be dissolved in an organic solvent such as 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), gamma-butyrolactone, or a mixture thereof.

[0179] FIG. 14 shows another embodiment of the electrode assembly 1. As shown in FIGS. 5 and 6, when electrode tabs 23 are connected to the region where the active material is applied in the axial direction, the thick electrode tabs 23 cause the radial thickness of the jelly roll in the circumferential region where the electrode tabs 23 are disposed to be thicker than in other regions. To minimize this thickness deviation, the embodiment illustrates a structure in which multiple electrode tabs 23 are disposed at different positions in the circumferential direction. When multiple electrode tabs 23 are disposed at different positions in the circumferential direction, it is preferable to dispose them at substantially equal intervals in the circumferential direction. For example, when three electrode tabs 23 are provided as shown in the figure, the angle between them may be approximately 120 degrees.

[0180] Of course, the radial distances at which the electrode tabs 23 are located from the center of the electrode assembly 1 may also vary, as shown in the figures. The positioning of the electrode tabs 23 has already been described with reference to Figures 5 and 6. The radial spacing between the electrode tabs 23 may gradually decrease from the centripetal side to the centrifugal side. For example, if the radii of the electrode tabs located from the most centripetal side to the most centrifugal side are r1, r2, r3, and r4, the relationship may be (r2-r1)>(r3-r2)>(r4-r3).

[0181] The electrode tabs 23 may be elastically deformed in the centripetal direction and may overlap each other in part. They may be welded to the cover 63 simultaneously or sequentially.

[0182] 15 to 19 show another embodiment of the electrode assembly 1. Referring to Fig. 15, the first electrode 2 has a first electrode uncoated portion 21 on one axial side where no active material 22 is applied. A plurality of first electrode tabs 23 are fixed to and electrically connected to the first electrode uncoated portion 21.

[0183] The second electrode 4 has a second electrode uncoated portion 41 on the other axial side where the active material 42 is not applied. The axial extension length of the second electrode uncoated portion 41 gradually or stepwise increases from the center to the centrifugal side. The second electrode uncoated portion 41 may be formed in the shape of a notched tab, and the base end of the notched tab may be bent to lie horizontally in the radial direction.

[0184] Certain sections on the most centripetal and most distal sides may not have notched tabs. The sections without notched tabs are not bent. One turn on the distal side can be removed during the manufacturing process to prevent the notched tab from deforming in unexpected circumstances.

[0185] The first electrode tab 23 does not extend in the width direction (Y) into the area where the first electrode active material 22 is applied. Therefore, even when the first electrode 2, the second electrode 4, and the separator 3 are wound up to form the electrode assembly 1, the first electrode tab 23 is not interposed in the area where the active materials 22, 42 are tightly attached in the radial direction. Therefore, even if the radius of the jelly roll repeatedly expands and contracts during charging and discharging, there is no area where excessive pressure is applied, and deterioration due to this can be prevented.

[0186] 15 shows an example in which the first electrode uncoated portion 21 is provided in a form that extends long in the longitudinal direction. In such a structure, if the first electrode uncoated portion 21 is too long, the risk of a short circuit increases, and if the first electrode uncoated portion 21 is too short, it is disadvantageous in ensuring a bonding area with the first electrode tab 23.

[0187] 16 shows a structure in which the height of first electrode uncoated region 21 is increased only in the section where first electrode tab 23 is attached, and first electrode uncoated region 21 is kept short in other areas. By reducing the height of first electrode uncoated region 21 in this way, it is possible to prevent first electrode uncoated region 21 from protruding further outward than separator 3.

[0188] In addition, as shown in FIG. 17, by removing the section to which the first electrode tab 23 is connected as well as the first electrode uncoated portion 21, it is possible to maximize the area of ​​the first electrode 2 that contributes to the capacitance.

[0189] In this way, with a structure in which a plurality of first electrode tabs 23 are connected to the first electrode uncoated portion 21 protruding toward one side in the axial direction, the first electrode tabs 23 can be arranged at positions that coincide with one another in the circumferential direction, as shown in Figures 18 and 19. Since the first electrode tabs 23 in the jelly roll are arranged at positions outside the active material coating layer anyway, there is no need to arrange them in a dispersed manner in the circumferential direction.

[0190] On the contrary, if they are arranged at substantially the same position in the circumferential direction, the plate-like first electrode tabs 23 are arranged substantially parallel to each other, as shown in the figure, and therefore they can be bent side by side. Therefore, compared to when the first electrode tabs 23 are arranged dispersedly in the circumferential direction, both welding to the lid 63 and handling after welding the lid 63 are easy. In particular, although they are spaced apart from each other in the radial direction, because they are arranged on the same radial line, the effect of reducing internal resistance is still achieved.

[0191] In particular, the positions where the first electrode tabs 23 should be provided are such that the first electrode uncoated regions 21 protrude to one side in the axial direction, and the first electrode uncoated regions 21 are provided higher in a predetermined section as shown in FIGS. 16 and 17, or the first electrode uncoated regions 21 are provided only in a predetermined section, but the first electrode uncoated regions 21 in that section protrude to one side in the axial direction, and the section is set wide to reflect the winding deviation. In this way, after the electrode assembly 1 is first wound, the first electrode tabs 23 can be brought into contact with and connected to the first electrode uncoated regions 21 protruding in the axial direction, thereby accurately aligning the circumferential positions of the first electrode tabs 23.

[0192] Furthermore, since the first electrode tabs 23 can be concentrated in the smallest area while maintaining an appropriate radial spacing, the insulating layer 65 can be formed to include only that area, which provides various advantages, such as facilitating the installation of the insulating layer 65 and allowing the first electrode tabs 23 to firmly contact the first electrode uncoated portion 21 via the insulating layer 65.

[0193] This structure of multiple first electrode tabs 23 can minimize the area of ​​the cover 63 that must be left open for welding to the first electrode tabs 23, regardless of the application of multiple first electrode tabs 23, and the position can be determined as a portion extending radially from one circumferential position (the area indicated by the two-dot chain line in Figures 18 and 19), making it convenient to apply a CID or vent to the cover 63 while connecting multiple first electrode tabs 23 to the cover 63.

[0194] Fig. 20 is a development view of the second electrode 4 in which the second electrode uncoated portion 41 is further coated with an insulating coating layer 44. Fig. 21 is an enlarged view of the second electrode uncoated portion 41 coated with the insulating coating layer of Fig. 20 after being wound up and folded.

[0195] The insulating coating layer 44 reinforces the rigidity of the vicinity of the base end of the second electrode uncoated portion 41. As a result, when the second electrode uncoated portion 41 receives an axial force from the second electrode current collector plate 52 or the bottom surface 62 of the battery can 6 in order to weld the second electrode uncoated portion 41, the base end of the second electrode uncoated portion 41 may not buckle.

[0196] When the base end of the second electrode uncoated portion 41 is reinforced with an insulating coating layer 44, even if the base end of the second electrode uncoated portion 41 buckles, the second electrode uncoated portion 41 and the first electrode 2 do not come into direct contact with each other but come into contact with each other via the insulating coating layer 44, thereby preventing a short circuit from occurring between the first electrode 2 and the second electrode 4.

[0197] The insulating coating layer 44 provides bending resistance in the process of bending the second electrode uncoated portion 41 in the radial direction. As a result, when the second electrode uncoated portion 41 is bent in the radial direction, the section coated with the insulating coating layer 44 is hardly deformed, and deformation occurs mainly in the section not coated with the insulating coating layer 44.

[0198] The insulating coating layer 44 covers a predetermined section from the boundary between the coating portion of the second electrode active material 42 and the second electrode uncoated portion 41 toward the end of the second electrode uncoated portion 41. The insulating coating layer 44 starts inside the axial end of the separator 3 and extends further outward in the axial direction than the separator 3.

[0199] When the insulating coating layer 44 covers the boundary between the coating portion of the second electrode active material 42 and the second electrode uncoated portion 41, it also covers a small section of the end of the coating portion of the second electrode active material 42. The portion where the greatest deformation due to buckling occurs may be the boundary between the coating portion of the second electrode active material 42 and the second electrode uncoated portion 41. Because the insulating coating layer 44 covers the small section of the end of the coating portion of the second electrode active material 42 at these boundary portions, it significantly increases the buckling resistance of the boundary portion between the coating portion of the second electrode active material 42 and the second electrode uncoated portion 41.

[0200] The insulating coating layer 44 may have a constant thickness or may have a thickness that varies along the axial direction. Figure 21 shows a structure in which the thickness of the insulating coating layer 44 gradually increases in a glide section (a section where the thickness decreases) formed at the edge of the negative active material.

[0201] The thickness of the insulating coating layer 44 may be thinner than the thickness of the negative electrode active material layer. As a result, as shown in the figure, the coating portion of the second electrode active material 42 may be in close contact with the separator 3 in the radial direction, but the insulating coating layer 44 may be spaced apart from the separator 3 to some extent, or may be in contact with the separator 3 but not in close contact.

[0202] As a result, even if an external force is applied to second electrode uncoated portion 41 and the base end of second electrode uncoated portion 41 is deformed during the process of bending second electrode uncoated portion 41 and the process of welding second electrode current collector plate 52 to second electrode uncoated portion 41, not only can the amount of deformation be reduced, but the deformation of the base end of second electrode uncoated portion 41 does not immediately affect separator 3. In other words, second electrode uncoated portion 41 has a section that does not affect separator 3 but is allowed to deform, equivalent to the distance between insulating coating layer 44 and separator 3.

[0203] Furthermore, when the insulating coating layer 44 is spaced apart from the separator 3, heat generated during the process of welding the second electrode uncoated portion 41 to the second electrode current collector plate 52 or the bottom surface 62 of the battery can 6 is prevented from being directly conducted to the separator 3 via the insulating coating layer 44, thereby protecting the separator 3 from the welding heat. Furthermore, the insulating coating layer 44 can further reduce the axial protrusion height of the separator 3, thereby further increasing the distance from the position where the welding heat is generated to the axial end of the separator 3, thereby further increasing the effect of protecting the separator 3 from the welding heat.

[0204] Because the electrode assembly 1 is wound into a cylindrical shape, the insulating coating region of the second electrode uncoated portion 41 coated with the insulating coating layer 44 also has a cylindrical curved surface. The cylindrical curved surface itself has bending resistance. According to the embodiment, the insulating coating region has a thicker cylindrical curved surface, so when the region above the cylindrical curved surface is bent in the radial direction, the insulating coating region provides higher bending resistance. As a result, bending is induced in the non-insulating coated portion of the second electrode uncoated portion 41.

[0205] In this case, since the insulating coating region provides higher bending resistance, the thickness of the insulating coating layer 44 is thinner than the thickness of the negative electrode active material layer, and the surface of the insulating coating layer 44 is spaced apart from the separator 3 in the radial direction, so that the bending resistance can be sufficiently exerted even if it is not supported by the separator 3.

[0206] The leading end of the insulating coating layer 44 is coated to maintain a slight gap (G) from the folding portion (F) of the second electrode uncoated portion 41. This has the effect of inducing folding of the second electrode uncoated portion 41 at the folding portion (F). In addition, since the second electrode uncoated portion 41 deforms with a slight gap (G) from the insulating coating layer 44, it is possible to prevent the insulating coating layer 44 from being damaged during the folding process of the uncoated portion.

[0207] In this way, the second electrode uncoated portion 41 having the insulating coating layer 44 can prevent buckling even when pressure is applied in the axial direction.

[0208] Fig. 22 is a perspective view showing a battery pack including a cylindrical battery cell according to the present invention, and Fig. 23 is a perspective view showing a vehicle including the battery pack of Fig. 22. Referring to these figures, the electrode assembly and cylindrical battery cell (C) according to the present invention can also be applied to a battery pack (P) including the electrode assembly and cylindrical battery cell (C) and a vehicle (V) including the battery pack (P). The implementation of these battery packs (P) and vehicles (V) is already known to those skilled in the art, and will not be described separately herein.

[0209] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the following claims rather than the above detailed description. All modifications and variations within the meaning and scope of the following claims, as well as equivalent concepts, should be construed as being included within the scope of the present invention.

[0210] Although the present invention has been described above with reference to illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by those skilled in the art within the technical scope of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described and explained while describing the embodiments of the present invention, it is natural that the effects that can be predicted by the configuration should also be recognized. [Explanation of symbols]

[0211] 1 Electrode assembly 2 1st electrode 21 First electrode (positive electrode) uncoated portion 22 First electrode (positive electrode) active material 23 First electrode (positive electrode) tab 3 Separation membrane 4 Second electrode (negative electrode) 41 Second electrode (negative electrode) uncoated area 42 Second electrode (negative electrode) active material 43 Second electrode (negative electrode) tab 44 insulating coating layer 5 Current collector plate 51 First electrode (positive electrode) current collector plate 52 Second electrode (negative electrode) current collector plate 6 battery cans 61 Side wall 62 bottom 63 Battery can lid 631 1st electrode terminal 633 Vent 64 Beading section 65 Insulating layer C Battery Cell P Battery pack V Automobile

Claims

1. A jelly roll electrode assembly in which a first electrode, a separator, a second electrode, and a separator are sequentially stacked and wound around a winding shaft in a winding direction, a first electrode tab electrically connected to the first electrode; a first electrode uncoated portion provided on a portion of the first electrode and not coated with an active material; and a second electrode uncoated portion provided on a portion of the second electrode and not coated with an active material; Including, the first electrode tab contacts the first electrode uncoated portion; the first electrode uncoated portion is provided in a form that further extends axially outward from an axial end of the region coated with the active material, The length of the first electrode uncoated portion extending outward in the axial direction is such that a first section including a portion contacted by the first electrode tab is longer than the other second section, the second electrode uncoated portion is exposed at the other axial end of the second electrode and serves as a tab; the first electrode uncoated portion in the second section is disposed axially inward of the separator.

2. A jelly roll electrode assembly in which a first electrode, a separator, a second electrode, and a separator are sequentially stacked and wound around a winding shaft in a winding direction, a first electrode tab electrically connected to the first electrode; a first electrode uncoated portion provided on a portion of the first electrode and not coated with an active material; and a second electrode uncoated portion provided on a portion of the second electrode and not coated with an active material; Including, the first electrode tab contacts the first electrode uncoated portion; the first electrode uncoated portion is provided in a form that further extends axially outward from an axial end of the region coated with the active material, a height of the first electrode uncoated portion extending axially outward, the first section including the portion where the first electrode tab contacts, is longer than a second section having a constant height and extending along the winding direction; The second electrode uncoated portion is exposed at the other axial end of the second electrode and serves as a tab.

3. One or more first electrode tabs are provided.

3. The electrode assembly according to claim 1 or 2.

4. two or more of the first electrode tabs overlap each other to form a single electrically connected tab; The electrode assembly according to claim 3 .

5. One of the first electrode tabs is connected to the first electrode at a position avoiding both ends of the first electrode in the winding direction. The electrode assembly according to claim 3 .

6. The two or more first electrode tabs are connected to the first electrode at positions avoiding both ends and a center portion of the first electrode in a winding direction. The electrode assembly according to claim 3 .

7. The first electrode uncoated portion is provided over the entire length or a part of the length.

3. The electrode assembly according to claim 1 or 2.

8. The first electrode tabs are provided in plural numbers, the plurality of first electrode tabs are arranged at different radial positions in the radial direction; 3. The electrode assembly according to claim 1 or 2.

9. The first electrode tabs are provided in plural numbers, The first electrode tabs are arranged at positions in the circumferential direction that do not overlap each other.

3. The electrode assembly according to claim 1 or 2.

10. The first electrode tabs are provided in plural numbers, the first electrode tabs are arranged at positions in the circumferential direction that at least partially overlap one another; 3. The electrode assembly according to claim 1 or 2.

11. The axial length of the first electrode is shorter than the axial length of the region of the second electrode coated with the active material and the separator.

3. The electrode assembly according to claim 1 or 2.

12. the second electrode uncoated portion has a shape in which notches are formed continuously or intermittently in the winding direction; 3. The electrode assembly according to claim 1 or 2.

13. the second electrode uncoated portion has a height that protrudes in the axial direction that increases continuously or intermittently; 3. The electrode assembly according to claim 1 or 2.

14. the second electrode uncoated portion is bent in a radial direction; 3. The electrode assembly according to claim 1 or 2.

15. A current collecting plate is coupled to the surface of the bent second electrode uncoated portion. The electrode assembly of claim 14.

16. The width of the first section is wider than the width of the first electrode tab.

3. The electrode assembly according to claim 1 or 2.

17. The electrode assembly according to claim 1 or 2, Cylindrical battery.

18. a battery can having one axial side open and accommodating the electrode assembly such that the second electrode uncoated portion faces the bottom; a battery can lid that covers the open top of the battery can when the electrode assembly is housed in the battery can; and an insulating layer insulating the first electrode tab from the battery can and the axial end of the second electrode; Including, the first electrode tab is electrically connected to the battery can lid; the second electrode uncoated portion is electrically connected to the bottom surface of the battery can; 18. The cylindrical battery of claim 17.

19. a beading portion protruding radially inward from a side wall of the battery can to fix the electrode assembly vertically; the insulating layer is disposed between the beading portion and the electrode assembly; 19. The cylindrical battery of claim 18.

20. The insulating layer covers one axial side of the electrode assembly, and the first electrode tab penetrates the insulating layer and protrudes to one axial side.

19. The cylindrical battery of claim 18.

21. the insulating layer is provided at each boundary between the first electrode tab, the second electrode, and the battery can; 19. The cylindrical battery of claim 18.

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