Electrode assembly, method for manufacturing an electrode assembly, and rechargeable battery

Abstract

An electrode assembly of a rechargeable battery includes a separator, first and second electrodes stacked and wound together with the separator interposed between the first and second electrodes, and a protective layer covering at least one of two end portions of the first electrode in a winding direction. The protective layer includes a first protective layer disposed in contact with one surface of the first electrode, and a second protective layer disposed in contact with the other surface of the first electrode and the first protective layer. An end portion of the first protective layer on the one surface and an end portion of the second protective layer on the other surface are at positions spaced apart from each other in the winding direction.

Description

Technical Field

[0001] This disclosure relates to rechargeable batteries, and more specifically, to wound electrode assemblies and methods of manufacturing the same, and rechargeable batteries having the electrode assemblies. Background Technology

[0002] Rechargeable batteries are used for a variety of purposes, such as powering small electronic devices like mobile phones and laptops, and powering motors in vehicles such as electric and hybrid vehicles. Based on their external shape, rechargeable batteries can be classified as cylindrical, prismatic, pouch-shaped, etc. Among them, cylindrical rechargeable batteries may include a wound electrode assembly in which two electrodes and a separator between the two electrodes are wound in a spiral shape.

[0003] In a wound electrode assembly, the electrodes can be manufactured through the following process: forming an active material layer by strip coating on a strip-shaped substrate, and then cutting the substrate coated with the active material layer to separate it into individual electrodes. However, during the cutting of the substrate and the active material layer, components of the active material layer may detach from the active material layer. These detached components may adhere to electrodes of opposite polarity or flow into areas inside the rechargeable battery other than the corresponding electrodes. In this case, the output voltage of the rechargeable battery may decrease. Summary of the Invention

[0004] This disclosure aims to provide such an electrode assembly and a method for manufacturing the same, as well as a rechargeable battery having the electrode assembly, which can prevent a decrease in the output voltage of the rechargeable battery by preventing components of the active material layer that detach from the active material layer during the cutting of the substrate and the active material layer from adhering to the electrode of the opposite polarity or flowing into the interior of the rechargeable battery except for the corresponding electrode. [Technical Solution]

[0005] According to one embodiment, an electrode assembly includes: a diaphragm; a first electrode and a second electrode, stacked and wound together with the diaphragm between the first electrode and the second electrode; and a protective layer covering at least one end of two ends of the first electrode along a winding direction. The protective layer includes: a first protective layer arranged to contact one surface of the first electrode; and a second protective layer arranged to contact the other surface of the first electrode and the first protective layer. The ends of the first protective layer on one surface and the ends of the second protective layer on the other surface are spaced apart from each other along the winding direction.

[0006] A portion of the first protective layer may overlap with the first electrode, and the remainder of the first protective layer may extend outward from the end of the first electrode. A portion of the second protective layer may overlap with the first electrode, and the remainder of the second protective layer may extend outward from the end of the first electrode and may contact the remainder of the first protective layer. Each of the first and second protective layers may consist of a polymer film with an adhesive material coated on one surface facing each other.

[0007] The first electrode may include a substrate, an active material layer on at least one surface of the substrate, and an uncoated portion at a longitudinal edge of the substrate. The active material layer may include a negative electrode active material and may be located at two ends of the substrate. Each of the first and second protective layers may include an extension extending outward from the first electrode along its width direction. The first and second protective layers may have different colors.

[0008] The uncoated portion may include a pair of uncoated edges contacting both ends of the substrate and a central uncoated portion located between the pair of uncoated edges. A protective layer may be located at a position spaced apart from the central uncoated portion along the winding direction. The protective layer may overlap with the active material layer and the uncoated edges. Extensions may extend to the outer sides of both sides of the first electrode.

[0009] On the other hand, the uncoated portion can have a constant width. The protective layer can overlap with the active material layer and the uncoated portion. The extended portion can be located on the opposite side of the uncoated portion along the width direction of the first electrode. Alternatively, the protective layer may not overlap with the uncoated portion.

[0010] According to one embodiment, a method for manufacturing an electrode assembly includes: (i) forming an active material layer by strip coating on a substrate, and slicing the substrate and the active material layer to manufacture a first electrode; (ii) spacing two first electrodes separated by slicing; (iii) introducing a first protective layer and a second protective layer to contact the two first electrodes, and slicing the central portions of the first and second protective layers to manufacture a protective layer; and (iv) stacking and winding the first electrode, the diaphragm, and the second electrode. The first and second protective layers introduced during the manufacture of the protective layer have different lengths.

[0011] The active material layer may include a negative electrode active material and may be located on both surfaces of the substrate. A first protective layer may be introduced to simultaneously contact one surface of the two first electrodes, and a second protective layer may be introduced to simultaneously contact the other surface of the two first electrodes. The first and second protective layers may contact each other at their central portions.

[0012] Each of the first and second protective layers may consist of a polymer film with an adhesive material coated on one surface facing each other. Each of the first and second protective layers may include an extension extending along the width direction of the first electrode to the outside of the first electrode. During the manufacturing process of the protective layers, visual inspection methods can be used to check whether the width of the extension falls within a reference range. The first and second protective layers may have different colors.

[0013] According to one embodiment, a rechargeable battery includes: an electrode assembly; a housing for receiving the electrode assembly within an internal space; and a cover plate coupled to an end of the housing to seal the housing. The electrode assembly includes: a separator; a first electrode and a second electrode, stacked and wound together with the separator between the first and second electrodes; and a protective layer covering at least one end of the two ends of the first electrode along a winding direction. The protective layer includes: a first protective layer in contact with one surface of the first electrode; and a second protective layer in contact with the other surface of the first electrode and the first protective layer. The ends of the first protective layer on one surface and the ends of the second protective layer on the other surface are spaced apart from each other along the winding direction.

[0014] The first electrode may include a first active material layer having a negative electrode active material. The first active material layer may be located at two ends of the first electrode. Each of the first protective layer and the second protective layer may include an extension extending outward along the width direction of the first electrode. The first protective layer and the second protective layer may have different colors. [Beneficial Effects]

[0015] According to the embodiments, the electrode assembly can prevent negative electrode active material detached from the first active material layer from adhering to the second electrode of opposite polarity or flowing into areas inside the rechargeable battery other than the first electrode. Furthermore, the different lengths of the first and second protective layers can suppress stress concentration on specific portions of the electrode assembly and prevent the formation of cracks in the electrode assembly. Attached Figure Description

[0016] Figure 1 This is a perspective view of the electrode assembly according to the first embodiment.

[0017] Figure 2 It is shown Figure 1 An exploded perspective view of the electrode assembly in its unfolded state, as shown in the figure.

[0018] Figure 3 yes Figure 1 The image shows a partially enlarged cross-sectional view of the electrode assembly.

[0019] Figure 4 yes Figure 2 A partial plan view of the first electrode in the electrode assembly shown in the figure.

[0020] Figure 5 yes Figure 2 A cross-sectional view of the first electrode in the electrode assembly shown in the figure.

[0021] Figure 6 It is shown Figure 1 The image shows a magnified cross-sectional view of the central region of the electrode assembly.

[0022] Figure 7 It is shown Figure 1 The image shows a partially enlarged cross-sectional view of the outer region of the electrode assembly.

[0023] Figure 8 This is an exploded perspective view showing the electrode assembly in its unfolded state according to the second embodiment.

[0024] Figure 9 yes Figure 8 A magnified view of a portion of the image.

[0025] Figure 10 This is a partially enlarged cross-sectional view of the electrode assembly according to the second embodiment.

[0026] Figure 11 This is an exploded perspective view showing the electrode assembly in its unfolded state according to the third embodiment.

[0027] Figure 12 This is a process flow diagram illustrating a method for manufacturing an electrode assembly according to one embodiment.

[0028] Figure 13 and Figure 14 It is shown Figure 12 A schematic diagram of process S10.

[0029] Figure 15 It is shown Figure 12 A schematic diagram of process S20.

[0030] Figure 16 It is shown Figure 12 A schematic diagram of process S30.

[0031] Figure 17 It is shown Figure 12 A schematic diagram of process S40.

[0032] Figure 18 It is shown Figure 12 A schematic diagram of process S50.

[0033] Figure 19 This is a perspective view of a rechargeable battery according to one embodiment;

[0034] Figure 20 yes Figure 19 The image shows a cross-sectional view of a rechargeable battery.

[0035] Figure 21 It is shown Figure 20 A cross-sectional view of a modified example of a rechargeable battery shown in the figure. Detailed Implementation

[0036] In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can readily practice the invention. The invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0037] Figure 1 This is a perspective view of the electrode assembly according to the first embodiment. Figure 2 It is shown Figure 1 An exploded perspective view of the electrode assembly in its unfolded state, as shown in the figure. Figure 3 yes Figure 1 The figure shows a partially enlarged cross-sectional view of the electrode assembly. For convenience, based on the figure, the upward direction is defined as the upper direction, and the downward direction is defined as the lower direction.

[0038] refer to Figures 1 to 3 The electrode assembly 100 of this embodiment includes: a diaphragm 30; a first electrode 10 and a second electrode 20, stacked and wound together with the diaphragm 30 between the first electrode 10 and the second electrode 20; and a protective layer 40 located at at least one of a first end 15 and a second end 16 of the first electrode 10. The first end 15 may be located at the winding center of the electrode assembly 100, and the second end 16 may be located at the outermost portion of the electrode assembly 100.

[0039] The electrode assembly 100 can be configured such that the laminate including the first electrode 10, the diaphragm 30, and the second electrode 20 is wound multiple times around a central pin (not shown). That is, the first electrode 10, the diaphragm 30, and the second electrode 20 can be wound into an electrode core shape. Each of the first electrode 10, the diaphragm 30, and the second electrode 20 can be formed into an elongated shape. After the electrode assembly 100 is wound, the central pin can be removed, and in this case, the empty space can be located at the center of the electrode assembly 100.

[0040] The laminate can be configured such that the second electrode 20, the diaphragm 30, the first electrode 10, and the diaphragm 30 are stacked from the inside to the outside in this order. Alternatively, the laminate can be configured such that the first electrode 10, the diaphragm 30, the second electrode 20, and the diaphragm 30 are stacked from the inside to the outside in this order. Figure 2In this embodiment, the former case is shown as an example. The first electrode 10 can be referred to as the negative electrode, and the second electrode 20 can be referred to as the positive electrode.

[0041] The first electrode 10 may include a first substrate 11 and a first active material layer 12 located on at least one surface of the first substrate 11. The first substrate 11 may be referred to as a negative electrode current collector, and the first active material layer 12 may be referred to as a negative electrode active material layer. The first substrate 11 may be made of copper, nickel, copper alloys, or nickel alloys, and may be in the form of a sheet or foam. The first active material layer 12 includes a negative electrode active material and may optionally further include an adhesive and / or a conductive material.

[0042] In the first active material layer 12, the negative electrode active material may include at least one of carbon-based active materials, lithium metal alloys, and silicon-carbon composite active materials. The carbon-based active material may include at least one of natural graphite and artificial graphite. The lithium metal alloy may be an alloy of lithium with a metal selected from Na, K, Pb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Ba, Ra, Ge, Al, and Sn.

[0043] The silicon-carbon composite active material may include at least one of a first active material, a second active material, and a third active material. The first active material may include a plurality of silicon nanoparticles and an amorphous carbon coating on the surface of the silicon nanoparticles. The second active material may include a core comprising a silicon-carbon composite material and a polymer coating on the core. The third active material may include a core comprising a silicon-based material and a carbon-based coating on the core.

[0044] The second electrode 20 may include a second substrate 21 and a second active material layer 22 located on at least one surface of the second substrate 21. The second substrate 21 may be referred to as a positive current collector, and the second active material layer 22 may be referred to as a positive active material layer. The second substrate 21 may be made of aluminum or the like, and may be in the form of a sheet or foam. The second active material layer 22 includes a positive active material and may optionally further include an adhesive and / or a conductive material.

[0045] In the second active material layer 22, the positive electrode active material may include a lithium transition metal composite oxide. The lithium transition metal composite oxide may include at least one of, for example, lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, and cobalt-free nickel manganese-based oxides.

[0046] In each of the first active material layer 12 and the second active material layer 22, the adhesive may include at least one of aqueous adhesives, non-aqueous adhesives, and dry adhesives. In each of the first active material layer 12 and the second active material layer 22, the conductive material may include at least one of the following materials: carbon-based materials such as natural graphite, artificial graphite, carbon black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials including copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; and conductive polymers such as polyphenylene derivatives.

[0047] The separator 30 may be composed of a porous substrate or a porous substrate having a coating on at least one surface thereon. The porous substrate may include at least one of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester, polycarbonate, and polyimide. The coating may include an adhesive, and the adhesive may include a polyvinylidene fluoride compound. The separator 30 insulates the first electrode 10 from the second electrode 20 while allowing lithium ion movement.

[0048] In the first electrode 10, the first active material layer 12 may be located on the remaining portion of the first substrate 11 except for one longitudinal side (lower longitudinal side) edge. The portion of the surface of the first substrate 11 that is not covered by the first active material layer 12 and is exposed is called the first uncoated portion 13. The first uncoated portion 13 may be called the first substrate tab or the first electrode tab.

[0049] In the second electrode 20, the second active material layer 22 may be located on the remaining portion of the second substrate 21, excluding the edge of the other longitudinal side (upper longitudinal side). The portion of the surface of the second substrate 21 that is not covered by the second active material layer 22 and is exposed is called the second uncoated portion 23. The second uncoated portion 23 may be referred to as the second substrate tab or the second electrode tab.

[0050] Each of the first uncoated portion 13 and the second uncoated portion 23 may include a pair of edge uncoated portions 131, 231 and a central uncoated portion 132, 232 located between the pair of edge uncoated portions 131, 231. The height of the edge uncoated portions 131, 231, measured along the width direction (W direction) of the first electrode 10 and the second electrode 20 is less than the height of the central uncoated portions 132, 232. The two side surfaces of the central uncoated portions 132, 232 may have an inclined shape, but are not limited to such examples.

[0051] The uncoated portions 132 and 232 at the center can be bent inward toward the winding center of the electrode assembly 100 and overlap with the uncoated portions 132 and 232 located inside. Multiple cut lines can be located in the uncoated portions 132 and 232 to facilitate bending. The multiple cut lines can be formed along an inclined direction, but are not limited to such examples.

[0052] The uncoated center portion 132 is fixed to the first current collector, described later, and is used to transfer the current from the first electrode 10 to the first current collector. The uncoated center portion 232 is fixed to the second current collector, described later, and is used to transfer the current from the second electrode 20 to the second current collector. The inwardly bent and overlapping uncoated center portions 132 are beneficial to increasing the current collection efficiency of the first electrode 10, and the inwardly bent and overlapping uncoated center portions 232 are beneficial to increasing the current collection efficiency of the second electrode 20.

[0053] The first electrode 10 includes a first end 15 located at the winding center of the electrode assembly 100 and a second end 16 located at the furthest point from the winding center. The first end 15 and the second end 16 are located on opposite sides of each other along the longitudinal direction (L direction, the winding direction in the winding state) of the first electrode 10. The first end 15 may be referred to as the winding front end portion, and the second end 16 may be referred to as the winding rear end portion. The first active material layer 12 is located at the position where it contacts the first end 15 and the second end 16.

[0054] A protective layer 40 is provided at at least one of the first end 15 and the second end 16 of the first electrode 10 to cover that end. Figure 2 The diagram shows the protective layer 40 provided at both the first end 15 and the second end 16. The protective layer 40 prevents the first end 15 and the second end 16 from being exposed to the outside and traps components of the first active material layer 12 so that the components of the first active material layer 12 do not migrate to other places.

[0055] Figure 4 yes Figure 2 A partial plan view of the first electrode in the electrode assembly shown in the figure. Figure 5 yes Figure 2 A cross-sectional view of the first electrode in the electrode assembly shown in the figure.

[0056] refer to Figure 4 and Figure 5The protective layer 40 includes a first protective layer 41 arranged to contact a first surface A10 of the first electrode 10 and a second protective layer 42 arranged to contact a second surface A20 of the first electrode 10. The first surface A10 may be an inner surface of the first electrode 10 positioned towards the winding center, and the second surface A20 may be the opposite surface of the first surface A10, i.e., the outer surface of the first electrode 10. Figure 4 The first surface of the first electrode 10 is shown in the figure.

[0057] A portion of the first protective layer 41 may overlap with the first surface A10, and the remainder of the first protective layer 41 may be positioned by extending outward from either the first end 15 or the second end 16. A portion of the second protective layer 42 may overlap with the second surface A20, and the remainder of the second protective layer 42 may be positioned by extending outward from either the first end 15 or the second end 16. The first protective layer 41 and the second protective layer 42 may be in contact with each other on the outer sides of the first end 15 and the second end 16.

[0058] The length L1 of the first protective layer 41 along the longitudinal direction (L direction) of the first electrode 10 and the length L2 of the second protective layer 42 along the longitudinal direction (L direction) of the first electrode 10 can be different from each other. That is, the length L1 of the first protective layer 41 can be greater than the length L2 of the second protective layer 42, or the length L2 of the second protective layer 42 can be greater than the length L1 of the first protective layer 41. Figure 4 and Figure 5 The example shown is the case where the length L2 of the second protective layer 42 is greater than the length L1 of the first protective layer 41.

[0059] The inner end 411 of the first protective layer 41 may be located on the first surface A10, and the outer end 412 of the first protective layer 41 may be located on the outer side of the first end 15 or the second end 16. The inner end 421 of the second protective layer 42 may be located on the second surface A20, and the outer end 422 of the second protective layer 42 may be located on the outer side of the first end 15 or the second end 16.

[0060] The outer ends 412 of the first protective layer 41 and the outer ends 422 of the second protective layer 42 can coincide with each other. That is, along the thickness direction (T direction) of the first electrode 10, the outer ends 412 of the first protective layer 41 and the outer ends 422 of the second protective layer 42 can be located in a straight line. On the other hand, the inner ends 411 of the first protective layer 41 and the inner ends 421 of the second protective layer 42 can be arranged to be offset from each other along the longitudinal direction (L direction) of the first electrode 10. The distance between the inner ends 411 of the first protective layer 41 and the inner ends 421 of the second protective layer 42 can be equal to the length difference between the first protective layer 41 and the second protective layer 42.

[0061] The first protective layer 41 and the second protective layer 42 may be composed of adhesive tape. The adhesive tape may be composed of a polymer film coated with an adhesive material on a surface, and the polymer film may be, for example, composed of a film of polyimide, polyethylene terephthalate, or polystyrene.

[0062] The first electrode 10 can be manufactured by the following process, wherein: while the strip-shaped first substrate 11 wound on rollers moves between rollers, a first active material layer 12 is formed on the first substrate 11 by a strip coating method, and the first substrate 11 and the first active material layer 12 are cut by a cutter to separate them into individual first electrodes 10. The first end 15 and the second end 16 can be formed by this cutting process.

[0063] During the cutting of the first substrate 11 and the first active material layer 12, components of the first active material layer 12 (e.g., negative electrode active material such as graphite) may detach from the first active material layer 12. The detached negative electrode active material may adhere to the second electrode 20 of opposite polarity or flow into areas inside the rechargeable battery other than the first electrode 10. In this case, the output voltage of the rechargeable battery may decrease.

[0064] In the electrode assembly 100 of this embodiment, after the first end 15 and the second end 16 are formed by cutting the first substrate 11 and the first active material layer 12, a protective layer 40 is immediately introduced to the first end 15 and the second end 16 to cover them. Therefore, even if the negative electrode active material detaches from the first active material layer 12 during the cutting process of the first substrate 11 and the first active material layer 12, the detached negative electrode active material is trapped in the protective layer 40 and does not move to any location other than the first electrode 10.

[0065] The electrode assembly 100 with protective layer 40 in this embodiment can prevent negative electrode active material from adhering to the second electrode 20 or flowing into other parts of the rechargeable battery, and can prevent the output voltage of the rechargeable battery from decreasing.

[0066] Figure 6 It is shown Figure 1 The image shows a magnified cross-sectional view of the central region of the electrode assembly. Figure 7 It is shown Figure 1 The image shows a partially enlarged cross-sectional view of the outer region of the electrode assembly. Figure 6 and Figure 7 For convenience, the diagram of the diaphragm is omitted.

[0067] refer to Figure 6 and Figure 7The second electrode 20 and the first electrode 10 having a protective layer 40, together with the diaphragm between the first electrode 10 and the second electrode 20, are wound together to form an electrode assembly 100. At this time, because the inner ends 411, 421 of the first protective layer 41 and the second protective layer 42 are arranged to be offset from each other along the winding direction, cracks in the electrode assembly 100 are not caused.

[0068] If we assume that the first and second protective layers are of the same length, and that the inner ends of the first and second protective layers coincide, a sudden thickness change occurs in the first electrode at the inner ends of the first and second protective layers. In this case, stress concentrates on the portion of the first electrode that contacts the inner ends of the first and second protective layers, or on a specific portion of the adjacent second electrode, causing cracks to appear in either the first or second electrode. The appearance of cracks in the first or second electrode leads to damage to the electrode assembly.

[0069] In the electrode assembly 100 of this embodiment, because the inner ends 411 of the first protective layer 41 and 421 of the second protective layer 42 are arranged to be offset from each other along the winding direction, stress concentration on the portion of the first electrode 10 that contacts the inner ends 411 and 421 or on a specific portion of the adjacent second electrode 20 can be suppressed. As a result, the protective layer 40 does not cause cracks in the first electrode 10 or the second electrode 20, and damage to the electrode assembly 100 caused by cracks can be prevented.

[0070] On the other hand, the second active material layer 22 of the second electrode 20 can also be formed on the second substrate 21 by strip coating and then cut together with the second substrate 21. However, since the components of the second active material layer 22 are not easily detached from the second active material layer 22, it is acceptable not to provide a protective layer for the second electrode 20.

[0071] Refer again Figure 4 The first protective layer 41 and the second protective layer 42 may be located at positions spaced apart from the central uncoated portion 132 along the longitudinal direction (L direction) of the first electrode 10. The first protective layer 41 and the second protective layer 42 may cover a portion of the edge uncoated portion 131. In addition, the first protective layer 41 and the second protective layer 42 may include extensions 415 and 425 extending along the width direction (W direction) of the first electrode 10 to both sides (upper and lower sides) of the first electrode 10.

[0072] The electrode assembly 100 can undergo volume changes, wherein the electrode assembly 100 expands during the charging process and contracts during the discharging process, and this volume change is primarily due to the volume change of the first active material layer 12. Extensions 415, 425 of the protective layer 40 are used to suppress the occurrence of a short circuit between the first electrode 10 and the second electrode 20 by ensuring that even if the first electrode 10 contracts, the first active material layer 12 and the second active material layer 22 do not come into contact with each other.

[0073] The widths W1 and W2 of the extensions 415 and 425 can fall within a preset reference range. The reference range can be approximately 1 mm to 3 mm, and as another example, approximately 1 mm to 2 mm. For example, the width W1 of the extensions 415 and 425 extending to the lower side of the first electrode 10 where the first uncoated portion 13 is located can be approximately 1 mm to 2 mm, and the width W2 of the extensions 415 and 425 extending to the upper side of the first electrode 10 can be approximately 1 mm to 3 mm.

[0074] If the widths W1 and W2 of the extensions 415 and 425 are smaller than the reference range, it may be difficult to implement the function of suppressing the occurrence of short circuits between the first electrode 10 and the second electrode 20. If the widths W1 and W2 of the extensions 415 and 425 exceed the reference range, the finishing quality of the electrode assembly 100 may be reduced, and the protective layer 40 may cause interference with other parts of the rechargeable battery.

[0075] The distance D1 between the outer ends 412, 422 of the first protective layer 41 and the second protective layer 42 and the first end 15 or the second end 16 can be within approximately 5 mm. The distance D2 between the inner end 411 of the first protective layer 41 and the first end 15 or the second end 16 can be within approximately 5 mm. The distance D3 between the inner end 421 of the second protective layer 42 and the first end 15 or the second end 16 can be within approximately 8 mm. D1 to D3 are not limited to the foregoing examples.

[0076] During the manufacturing process of the first electrode 10, it is necessary to check whether the widths W1 and W2 of the extension portions 415 and 425 fall within the reference range, and the first electrode whose widths W1 and W2 of the extension portions 415 and 425 deviate from the reference range can be considered defective. A visual inspection machine (not shown) can be used to check whether the widths W1 and W2 of the extension portions 415 and 425 fall within the reference range, and for the accuracy of the visual inspection, the first protective layer 41 and the second protective layer 42 can have different colors.

[0077] A visual inspection machine can distinguish and measure the width W1 of the extension portion 415 of the first protective layer 41 and the width W2 of the extension portion 425 of the second protective layer 42 by using the color difference between the first protective layer 41 and the second protective layer 42. For example, the first protective layer 41 and the second protective layer 42 can be composed of a combination of blue and red, a combination of blue and yellow, a combination of green and red, or a combination of green and yellow. The following table shows the detection error rate based on the color combination of the first protective layer 41 and the second protective layer 42. [Table 1]

[0078] The results in the table above show that the highest detection accuracy is achieved when the first protective layer 41 and the second protective layer 42 are composed of a combination of blue and red.

[0079] Figure 8 This is an exploded perspective view showing the electrode assembly in its unfolded state according to the second embodiment. Figure 9 yes Figure 8 A magnified view of a portion of the image. Figure 10 This is a partially enlarged cross-sectional view of the electrode assembly according to the second embodiment. Except for the configuration described below, the electrode assembly of the second embodiment consists of the same or similar configuration as that of the first embodiment described above.

[0080] refer to Figures 8 to 10 In the electrode assembly of this embodiment, the first uncoated portion 13 may have a constant width along the longitudinal direction (L direction) of the first electrode 10. The second uncoated portion 23 may have a constant width along the longitudinal direction (L direction) of the second electrode 20. The first uncoated portion 13 may be fixed to the first current collector described later in an unbent state, and the second uncoated portion 23 may be fixed to the second current collector described later in an unbent state.

[0081] The first protective layer 41 and the second protective layer 42 may cover the first uncoated portion 13. In addition, the first protective layer 41 and the second protective layer 42 may include extension portions 415 and 425 extending along the width direction (W direction) of the first electrode 10 to the outside of the first active material layer 12.

[0082] For example, the first active material layer 12 may include a third end 121 in contact with the first uncoated portion 13 and a fourth end 122 located on the opposite side of the third end 121. The third end 121 and the fourth end 122 are located on opposite sides of each other along the width direction (W direction) of the first electrode 10. The extension portions 415 and 425 may be portions extending to the outside of the fourth end 122. The width W3 of the extension portions 415 and 425 may be the same as the widths W1 and W2 of the extension portions described in the first embodiment, and redundant descriptions will be omitted.

[0083] Figure 11 This is an exploded perspective view showing the electrode assembly according to the third embodiment in its unfolded state. Except for the configuration described below, the electrode assembly of the third embodiment consists of the same or similar configuration as that of the second embodiment described above.

[0084] refer to Figure 11 In the electrode assembly of this embodiment, the protective layer 40 may not cover the first uncoated portion 13. That is, the protective layer 40 may overlap with a portion of the first active material layer 12, excluding the first uncoated portion 13. The first uncoated portion 13 is fixed to the first current collector and is used to transfer the current from the first electrode 10 to the first current collector. When the first uncoated portion 13 is not covered by the protective layer 40, the entire first uncoated portion 13 forms a good contact with the first current collector, thereby increasing the current collection effect.

[0085] Figure 12 This is a process flow diagram illustrating a method for manufacturing an electrode assembly according to one embodiment.

[0086] refer to Figure 12 The method for manufacturing an electrode assembly according to this embodiment includes the following processes: forming a first active material layer by strip coating on a first substrate, and cutting the first substrate and the first active material layer to manufacture a first electrode (S10); spacing two separate first electrodes apart (S20); introducing a first protective layer and a second protective layer to contact the two first electrodes (S30); cutting the central portions of the first protective layer and the second protective layer (S40); and stacking and winding the first electrode, the diaphragm and the second electrode (S50).

[0087] Figure 13 and Figure 14 It is shown Figure 12 A schematic diagram of process S10. Figure 15 It is shown Figure 12 A schematic diagram of process S20. Figure 16 It is shown Figure 12 A schematic diagram of process S30. Figure 17 It is shown Figure 12 A schematic diagram of process S40. Figure 18 It is shown Figure 12 A schematic diagram of process S50.

[0088] refer to Figure 13 The first substrate 11 moves from the first roller 51 toward the second roller 52, and the coating apparatus 60 can be disposed on both sides (upper and lower sides) of the moving first substrate 11. The coating apparatus 60 can manufacture the first active material layer 12 by continuously discharging components of the first active material layer 12 onto both surfaces of the moving first substrate 11. The first active material layer 12 includes a negative electrode active material and may optionally further include an adhesive and / or a conductive material.

[0089] refer to Figure 14 and Figure 15 The first substrate 11 and the first active material layer 12 can be cut by the cutter 71 into two first electrodes 10 (S10). Either of the two separate first electrodes 10 can be moved so that the two first electrodes are spaced apart from each other (S20).

[0090] The first protective layer introduction device 81 and the second protective layer introduction device 82 can be disposed on both sides (upper and lower sides) of two first electrodes 10 spaced apart from each other. The end of either of the two first electrodes 10 can be a first end 15, and the end of the other first electrode 10 can be a second end 16.

[0091] refer to Figure 15 and Figure 16 The first protective layer introducing device 81 can introduce a first protective layer 41 to simultaneously contact the first surfaces 10A of both first electrodes 10, and the second protective layer introducing device 82 can introduce a second protective layer 42 to simultaneously contact the second surfaces 10B of both first electrodes 10. The first protective layer 41 and the second protective layer 42 can be composed of polymer films having adhesive layers located on their surfaces facing each other. The first protective layer 41 and the second protective layer 42 can be bonded to each other in the space between the two first electrodes 10 (S30).

[0092] Immediately after the cutting process of the first electrode 10, the first protective layer 41 and the second protective layer 42 are introduced to the first end 15 and the second end 16 of the first electrode 10 to cover the first end 15 and the second end 16. Therefore, even if a portion of the negative electrode active material detaches from the first active material layer 12 during the cutting process, the detached negative electrode active material can be trapped in the first protective layer 41 and the second protective layer 42.

[0093] At this time, the first protective layer 41 and the second protective layer 42 can be provided with different lengths so that the ends 411 of the first protective layer 41 and the ends 421 of the second protective layer 42 do not coincide with each other along the thickness direction (T direction) of the first electrode 10. That is, the ends 411 of the first protective layer 41 and the ends 421 of the second protective layer 42 can be arranged to be offset from each other along the longitudinal direction (L direction) of the first electrode 10.

[0094] like Figure 4 As shown, each of the first protective layer 41 and the second protective layer 42 may include extension portions 415 and 425, and a visual inspection method can be used to check whether the widths W1 and W2 of the extension portions 415 and 425 fall within a reference range. The apparatus for visual inspection may include a camera and an image analysis unit, and by using the camera to capture images of the extension portions 415 and 425 and analyzing the image information in the image analysis unit, it is possible to check whether the widths W1 and W2 of the extension portions 415 and 425 fall within the reference range.

[0095] To ensure the accuracy of visual inspection, the first protective layer 41 and the second protective layer 42 can be different colors. For example, the first protective layer 41 and the second protective layer 42 can be composed of a combination of blue and red, which indicates high detection accuracy. The first electrode in which the widths W1 and W2 of the extensions 415 and 425 deviate from the reference range can be considered defective.

[0096] refer to Figure 5 and Figure 17 The central portions of the first protective layer 41 and the second protective layer 42 can be cut by the cutter 72 to separate the protective layer 40 into two parts (S40). Through the cutting of the protective layer 40, the outer ends 412 and 422 of the first protective layer 41 and the second protective layer 42 can be positioned on a straight line along the thickness direction (T direction) of the first electrode 10. The ends 411 and 421 of the first protective layer 41 and the second protective layer 42 that contact the first active material layer 12 can become the inner ends.

[0097] refer to Figure 18 The first electrode 10, the second electrode 20, and the two diaphragms 30 can form a laminate, and the laminate can be wound around the central pin 90. The laminate can be configured such that the second electrode 20, the diaphragm 30, the first electrode 10, and the diaphragm 30 are stacked in this order, starting from the inside facing the central pin 90. The positions of the first electrode 10 and the second electrode 20 can be switched. A protective layer 40 is located at at least one of the two ends of the first electrode 10.

[0098] Because the protective layer 40 captures the negative electrode active material that detaches from the first active material layer 12 during the cutting process, it prevents the negative electrode active material from adhering to the second electrode 20 of the opposite polarity or flowing into other parts of the rechargeable battery besides the first electrode 10. Furthermore, the different lengths of the first protective layer 41 and the second protective layer 42 can suppress stress concentration on specific portions of the electrode assembly 100 and prevent the formation of cracks in the electrode assembly 100.

[0099] refer to Figure 3 In the case of the electrode assembly of the first embodiment, during the winding of the laminate, the center uncoated portion 132 of the first uncoated portion 13 and the center uncoated portion 232 of the second uncoated portion 23 can be bent toward the winding center (S50). For example, the center uncoated portions 132 and 232 can be initially bent toward the winding center of the electrode assembly by high-pressure air during the winding process, and can be bent a second time by pressing with a clamp (not shown) after the electrode assembly is wound.

[0100] The uncoated central portions 132 and 232 can be flattened by undergoing two stages of bending to overlap with the portions located inside them. The bent uncoated central portion 132 can then be fixed to the first current collector by a method such as laser welding. The bent uncoated central portion 232 can then be fixed to the second current collector by a method such as laser welding.

[0101] Figure 19 This is a perspective view of a rechargeable battery according to one embodiment. Figure 20 yes Figure 19 The image shows a cross-sectional view of a rechargeable battery. Figure 21 It is shown Figure 20 A cross-sectional view of a modified example of a rechargeable battery shown in the figure.

[0102] refer to Figures 19 to 21 The rechargeable battery 1000, 2000 of this embodiment may include a cylindrical housing 200, an electrode assembly 100 housed inside the housing 200, a terminal portion 300 provided on one side (upper side) of the housing 200, and a cover plate 400 provided on the other side (lower side) of the housing 200.

[0103] The electrode assembly 100 is the electrode assembly of any one of the first to third embodiments described above. Figure 20 The electrode assembly 100 is the electrode assembly of the first embodiment described above, and Figure 21 The electrode assembly 100 is the electrode assembly of the second or third embodiment described above.

[0104] The first uncoated portion of the first electrode 10 is fixed to and electrically connected to the first current collector 510. The second uncoated portion of the second electrode 20 is fixed to and electrically connected to the second current collector 520. The first current collector 510 and the second current collector 520 may be located on opposite sides of each other. The electrode assembly 100, the first current collector 510, and the second current collector 520 may be housed together with the electrolyte inside the housing 200.

[0105] The housing 200 may include a disc-shaped upper surface portion 210 and a cylindrical side portion 220 extending downward from the edge of the upper surface portion 210. The housing 200 may have a cylindrical shape with a closed top surface and an open bottom end. The housing 200 may be made of, for example, steel, steel alloy, aluminum, aluminum alloy, etc. When the top and bottom of the rechargeable batteries 1000 and 2000 are switched, the upper surface portion 210 may be referred to as the bottom portion.

[0106] The terminal hole may be located at the center of the upper surface portion 210, and the terminal portion 300 may be installed in the terminal hole. The terminal portion 300 may include a disc-shaped first terminal 310, a generally cylindrical second terminal 320, and first to third insulators 330, 340, and 350. The first terminal 310 may be referred to as a terminal plate, and the second terminal 320 may be referred to as a riveted terminal. The first terminal 310 may be disposed on the outer side of the upper surface portion 210, and the second terminal 320 may be fitted into the terminal hole. The second terminal 320 may be connected to the first terminal 310 and the upper surface portion 210 by riveting.

[0107] The second terminal 320 can be connected to the second current collector 520, and the first terminal 310 and the second terminal 320 can maintain the same polarity as the second current collector 520. That is, the first terminal 310 and the second terminal 320 can be charged through the second current collector 520 with the same polarity as the second electrode 20 of the electrode assembly 100, and can be used as positive terminals.

[0108] The first insulator 330 may be located on the outside of the upper surface portion 210 between the upper surface portion 210 and the first terminal 310. The second insulator 340 surrounds the second terminal 320 and may be located between the second terminal 320 and the upper surface portion 210. The third insulator 350 may be located on the inside of the upper surface portion 210 between the upper surface portion 210 and the second current collector 520. The first to third insulators 330, 340, and 350 may insulate the housing 200 from the first terminal 310 and the second terminal 320.

[0109] Optionally, an insulating cover 600 may be additionally disposed between the third insulator 350 and the second current collector 520. The insulating cover 600 may cover a portion of the upper surface of the second current collector 520 and may extend to cover a portion of the side surface of the electrode assembly 100. The insulating cover 600 may prevent the electrode assembly 100 and the second current collector 520 from contacting the housing 200 and being energized.

[0110] The coiled portion 230 and the crimped portion 240 may be located on the side portion 220 of the housing 200. The coiled portion 230 may be located at the lower end adjacent to the side portion 220 and may be a portion that is concavely deformed toward the interior of the housing 200. The lower end portion of the side portion 220 spaced apart from the coiled portion 230 may be bent toward the interior of the housing 200 to become the crimped portion 240.

[0111] The first current collector 510 may include a disc-shaped plate-like portion 511 and a connecting portion 512 extending downward from the edge of the plate-like portion 511. The connecting portion 512 may be tightly attached to the inner surface of the coiled portion 230. Accordingly, the first current collector 510 may be electrically connected to the housing 200. The housing 200 may be charged through the first current collector 510 with the same polarity as the first electrode 10 of the electrode assembly 100, and may be used as a negative terminal.

[0112] On the other hand, although not shown, the first current collector can be connected to the first terminal and the second terminal so that the first terminal and the second terminal can be used as negative terminals, and the second current collector can contact the housing so that the housing can be used as a positive terminal.

[0113] The cover plate 400 can be located on the outside (below) of the first current collector 510 and can be fixed between the rolled portion 230 and the crimped portion 240 via an insulating gasket 700. The cover plate 400 can seal the housing 200 and can be electrically neutralized by being insulated from the first electrode 10, the second electrode 20 and the housing 200.

[0114] The notch 410 may be located on at least one surface of the cover plate 400. The notch 410 may have a V-shaped cross-section and may be arc-shaped in plan view (when viewed from above). The rechargeable batteries 1000 and 2000 may experience internal temperature rise due to various reasons such as rapid charging / discharging, external impact, and exposure to high-temperature environments, and the internal pressure may rise due to electrolyte evaporation, etc. When the internal pressure of the rechargeable batteries 1000 and 2000 rises, the cover plate 400 may break from the notch 410 to release internal gas.

[0115] In the aforementioned rechargeable batteries 1000 and 2000, a protective layer 40 (see [see details]) is provided on the first electrode 10. Figure 2The negative electrode active material does not flow into any place other than the first electrode 10. Therefore, the rechargeable batteries 1000 and 2000 of this embodiment can prevent the output voltage from decreasing due to the negative electrode active material flowing into places other than the first electrode 10.

[0116] While preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications may be made within the scope of the claims, the detailed description of the present invention, and the accompanying drawings, and such modifications naturally fall within the scope of the present invention.

Claims

1. An electrode assembly, comprising: Diaphragm; The first electrode and the second electrode are stacked and wound together with the diaphragm between the first electrode and the second electrode; A protective layer covers at least one end of the first electrode along the winding direction, wherein The protective layer includes: a first protective layer arranged to contact a surface of the first electrode; A second protective layer is arranged to contact the other surface of the first electrode and the first protective layer, and The ends of the first protective layer on one surface and the ends of the second protective layer on the other surface are spaced apart from each other along the winding direction.

2. The electrode assembly according to claim 1, wherein: A portion of the first protective layer overlaps with the first electrode, and the remainder of the first protective layer extends outward from the end of the first electrode. A portion of the second protective layer overlaps with the first electrode, and the remainder of the second protective layer extends outward from the end of the first electrode and contacts the remainder of the first protective layer.

3. The electrode assembly according to claim 2, wherein: Each of the first protective layer and the second protective layer consists of a polymer film coated with an adhesive material on one surface facing each other.

4. The electrode assembly according to claim 1, wherein: The first electrode includes a substrate, an active material layer on at least one surface of the substrate, and an uncoated portion located at a longitudinal side edge of the substrate. The active material layer includes a negative electrode active material and is located at two ends of the substrate.

5. The electrode assembly according to claim 4, wherein: Each of the first protective layer and the second protective layer includes an extension that extends outward from the first electrode along the width direction of the first electrode.

6. The electrode assembly according to claim 5, wherein: The first protective layer and the second protective layer have different colors.

7. The electrode assembly according to claim 5, wherein: The uncoated portion includes a pair of uncoated edges that contact the two ends of the substrate and a central uncoated portion located between the pair of uncoated edges. The protective layer is located at a position spaced apart from the uncoated central portion along the winding direction.

8. The electrode assembly according to claim 7, wherein: The protective layer overlaps with the active material layer and the uncoated edge portion, and The extension portion extends to the outside of both sides of the first electrode.

9. The electrode assembly according to claim 5, wherein: The uncoated portion has a constant width. The protective layer overlaps with the active material layer and the uncoated portion, and The extended portion is located on the opposite side to the uncoated portion along the width direction of the first electrode.

10. The electrode assembly according to claim 5, wherein: The uncoated portion has a constant width. The protective layer overlaps with the active material layer, and The extended portion is located on the opposite side to the uncoated portion along the width direction of the first electrode.

11. A method for manufacturing an electrode assembly, comprising: An active material layer is formed by strip coating on a substrate, and the substrate and the active material layer are cut to manufacture a first electrode; The two first electrodes are separated by cutting; A first protective layer and a second protective layer are introduced to contact the two first electrodes, and the central portions of the first protective layer and the second protective layer are cut to manufacture the protective layer; Stack and wind the first electrode, the diaphragm, and the second electrode; wherein: The first and second protective layers introduced during the manufacturing process have different lengths.

12. The method for manufacturing an electrode assembly according to claim 11, wherein: The active material layer includes a negative electrode active material and is located on both surfaces of the substrate.

13. The method for manufacturing an electrode assembly according to claim 11, wherein: The first protective layer is introduced to simultaneously contact one surface of the two first electrodes, and the second protective layer is introduced to simultaneously contact the other surface of the two first electrodes, with the first and second protective layers contacting each other at their central portions.

14. The method for manufacturing an electrode assembly according to claim 13, wherein: Each of the first protective layer and the second protective layer consists of a polymer film coated with an adhesive material on one surface facing each other.

15. The method for manufacturing an electrode assembly according to claim 11, wherein: Each of the first protective layer and the second protective layer includes an extension portion extending outward from the first electrode along the width direction of the first electrode, and During the manufacturing of the protective layer, a visual inspection method is used to check whether the width of the extension falls within the reference range.

16. The method for manufacturing an electrode assembly according to claim 15, wherein: The first protective layer and the second protective layer have different colors.

17. A rechargeable battery, comprising: An electrode assembly includes: a diaphragm; a first electrode and a second electrode, stacked and wound together with the diaphragm between the first electrode and the second electrode; and a protective layer covering at least one end of two ends of the first electrode along a winding direction. Housing for accommodating the electrode assembly within an internal space; and A cover plate, attached to the end of the housing to seal the housing, wherein: The protective layer includes: a first protective layer in contact with one surface of the first electrode; and a second protective layer in contact with the other surface of the first electrode and the first protective layer. The ends of the first protective layer on one surface and the ends of the second protective layer on the other surface are spaced apart from each other along the winding direction.

18. The rechargeable battery according to claim 17, wherein: The first electrode includes a first active material layer having a negative electrode active material, and The first active material layer is located at the two ends of the first electrode.

19. The rechargeable battery according to claim 18, wherein: Each of the first protective layer and the second protective layer includes an extension portion extending outward from the first electrode along the width direction of the first electrode, and The first protective layer and the second protective layer have different colors.

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