Electrode assembly, manufacturing method of electrode assembly, and rechargeable battery

Abstract

An electrode assembly of a rechargeable battery comprises: a separator; a first electrode and a second electrode that are stacked and wound with the separator therebetween; and a protective layer that covers at least one of both ends of the first electrode in the winding direction. The protective layer includes: a first protective layer located to be in contact with one surface of the first electrode; and a second protective layer located to be in contact with the other surface of the first electrode and the first protective layer. The end of the first protective layer located on the one surface and the end of the second protective layer located on the other surface are spaced apart from each other in the winding direction.

Description

Electrode assembly, method for manufacturing electrode assembly, and secondary battery

[0001] The present disclosure relates to a secondary battery, and more particularly, to a coiled electrode assembly, a method for manufacturing the same, and a secondary battery having the same.

[0002] Secondary batteries are used in a variety of applications, including powering small electronic devices like mobile phones and laptops, and powering motors in vehicles like electric and hybrid vehicles. Secondary batteries can be categorized by their external shape into cylindrical, prismatic, and pouch-shaped types. Cylindrical secondary batteries may include a coiled electrode assembly, in which two electrodes are wound in a circular shape with a separator between them.

[0003] In a roll-type electrode assembly, the electrodes can be manufactured by forming an active material layer by stripe coating on a long strip-shaped substrate, and then cutting the substrate coated with the active material layer to separate the electrodes into individual electrodes. However, during the cutting process between the substrate and the active material layer, the constituent materials of the active material layer may be removed from the active material layer. The removed active material may attach to an electrode of opposite polarity or flow into other locations within the secondary battery other than the electrode. In this case, the output voltage of the secondary battery may be reduced.

[0004] The present disclosure provides an electrode assembly capable of preventing a decrease in the output voltage of a secondary battery by preventing a component of an active material layer detached from an active material layer when cutting a substrate and an active material layer from attaching to an electrode of opposite polarity or flowing into a location other than the electrode within the secondary battery, a method for manufacturing the same, and a secondary battery having the same.

[0005] An electrode assembly according to one embodiment includes a separator, first and second electrodes laminated and wound with the separator therebetween, and a protective layer covering at least one end of both ends of the first electrode along the winding direction. The protective layer includes a first protective layer positioned to be in contact with one surface of the first electrode, and a second protective layer positioned to be in contact with the other surface of the first electrode and the first protective layer. An end of the first protective layer positioned on one surface and an end of the second protective layer positioned on the other surface are positioned with a distance from each other along the winding direction.

[0006] A portion of the first protective layer may overlap the first electrode, and the remainder of the first protective layer may extend outward from an end of the first electrode. A portion of the second protective layer may overlap the first electrode, and the remainder of the second protective layer may extend outward from an end of the first electrode and may be in contact with the remainder of the first protective layer. Each of the first protective layer and the second protective layer may be composed of a polymer film having an adhesive material applied to one surface facing each other.

[0007] The first electrode may include a substrate, an active material layer positioned on at least one surface of the substrate, and a non-conductive region positioned on one edge of the substrate. The active material layer may include a negative active material and may be positioned in contact with both ends of the substrate. Each of the first protective layer and the second protective layer may include an extension extending outward from the first electrode along the width direction of the first electrode. The first protective layer and the second protective layer may have different colors.

[0008] The non-coated portion may include a pair of edge non-coated portions that contact both ends of the substrate, and a central non-coated portion located between the pair of edge non-coated portions. The protective layer may be located at a distance from the central non-coated portion along the winding direction. The protective layer may overlap the active material layer and the edge non-coated portions. The extension portion may extend outside on both sides of the first electrode.

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

[0010] A method for manufacturing an electrode assembly according to one embodiment includes the steps of (i) forming an active material layer by stripe coating on a substrate, cutting the substrate and the active material layer to manufacture a first electrode, (ii) separating two first electrodes separated by cutting, (iii) introducing a first protective layer and a second protective layer so as to be in contact with the two first electrodes simultaneously, cutting a center portion of the first protective layer and the second protective layer to manufacture the protective layer, and (iv) stacking and winding the first electrode, a separator, and the second electrode. The first protective layer and the second protective layer introduced in the process of manufacturing the protective layer have different lengths.

[0011] The active material layer may include a negative active material and may be positioned on both sides of the substrate. The first protective layer may be applied so as to be in contact with one side of the two first electrodes simultaneously, and the second protective layer may be applied so as to be in contact with the other side of the two first electrodes simultaneously. The first protective layer and the second protective layer may be in contact with each other at the center.

[0012] The first protective layer and the second protective layer may be composed of polymer films having an adhesive material applied to one surface facing each other. Each of the first protective layer and the second protective layer may include an extension extending outward from the first electrode along the width direction of the first electrode. During the process of manufacturing the protective layer, a vision inspection method may be used to check whether the width of the extension falls within a standard range. The first protective layer and the second protective layer may have different colors.

[0013] A secondary battery according to one embodiment includes an electrode assembly, a case that accommodates the electrode assembly in an internal space, and a cap plate coupled to an end of the case to seal the case. The electrode assembly includes a separator, first and second electrodes that are laminated and wound with the separator therebetween, and a protective layer that covers at least one end of both ends of the first electrode along a winding direction. The protective layer includes a first protective layer that contacts one surface of the first electrode, and a second protective layer that contacts the other surface of the first electrode and the first protective layer. An end of the first protective layer located on one surface and an end of the second protective layer located on the other surface are located at a distance from each other along the winding direction.

[0014] The first electrode may include a first active material layer comprising a negative active material. The first active material layer may be positioned in contact with both ends of the first electrode. Each of the first protective layer and the second protective layer may include an extension extending outward from the first electrode along the width direction of the first electrode. The first protective layer and the second protective layer may have different colors.

[0015] According to embodiments, the electrode assembly can prevent the negative active material detached from the first active material layer from attaching to the second electrode of opposite polarity or from flowing into a location other than the first electrode within the secondary battery. In addition, the different lengths of the first and second protective layers can suppress stress concentration in a specific portion of the electrode assembly and prevent cracking in the electrode assembly.

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

[0017] Fig. 2 is an exploded perspective view showing the unfolded state of the electrode assembly illustrated in Fig. 1.

[0018] Figure 3 is a partially enlarged cross-sectional view of the electrode assembly shown in Figure 1.

[0019] FIG. 4 is a partial plan view of the first electrode of the electrode assembly illustrated in FIG. 2.

[0020] Fig. 5 is a cross-sectional view of the first electrode of the electrode assembly illustrated in Fig. 2.

[0021] Fig. 6 is a partially enlarged cross-sectional view showing the central area of ​​the electrode assembly illustrated in Fig. 1.

[0022] Fig. 7 is a partially enlarged cross-sectional view showing the outer region of the electrode assembly illustrated in Fig. 1.

[0023] Fig. 8 is an exploded perspective view showing the unfolded state of the electrode assembly according to the second embodiment.

[0024] Figure 9 is a partially enlarged view of Figure 8.

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

[0026] Fig. 11 is an exploded perspective view showing the unfolded state of the electrode assembly according to the third embodiment.

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

[0028] Figures 13 and 14 are schematic diagrams showing the S10 process of Figure 12.

[0029] Figure 15 is a schematic diagram showing the S20 process of Figure 12.

[0030] Figure 16 is a schematic diagram showing the S30 process of Figure 12.

[0031] Figure 17 is a schematic diagram showing the S40 process of Figure 12.

[0032] Figure 18 is a schematic diagram showing the S50 process of Figure 12.

[0033] Fig. 19 is a perspective view of a secondary battery according to one embodiment.

[0034] Figure 20 is a cross-sectional view of the secondary battery illustrated in Figure 19.

[0035] Fig. 21 is a cross-sectional view showing a modified example of the secondary battery illustrated in Fig. 20.

[0036] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0037] Fig. 1 is a perspective view of an electrode assembly according to the first embodiment. Fig. 2 is an exploded perspective view showing the electrode assembly illustrated in Fig. 1 in an unfolded state. Fig. 3 is a partially enlarged cross-sectional view of the electrode assembly illustrated in Fig. 1. For convenience, the upper side is defined as the upper direction and the lower side is defined as the lower direction based on the drawing.

[0038] Referring to FIGS. 1 to 3, the electrode assembly (100) of the present embodiment includes a separator (30), a first electrode (10) and a second electrode (20) that are laminated and wound with the separator (30) interposed therebetween, and a protective layer (40) positioned at at least one of the first end (15) and the second end (16) of the first electrode (10). The first end (15) is positioned at the center of the winding of the electrode assembly (100), and the second end (16) is positioned at the outermost edge of the electrode assembly (100).

[0039] The electrode assembly (100) may be configured as a laminate including a first electrode (10), a separator (30), and a second electrode (20) wound multiple times around a center pin (not shown). That is, the first electrode (10), the separator (30), and the second electrode (20) may be wound in a jelly roll shape. Each of the first electrode (10), the separator (30), and the second electrode (20) may be formed in a long strip shape. The center pin may be removed after the electrode assembly (100) is wound, in which case an empty space may be located at the center of the electrode assembly (100).

[0040] The laminate may be configured to be laminated in the order of a second electrode (20), a separator (30), a first electrode (10), and a separator (30) from the inside to the outside. Alternatively, the laminate may be configured to be laminated in the order of a first electrode (10), a separator (30), a second electrode (20), and a separator (30) from the inside to the outside. The former case is illustrated as an example in FIG. 2. In the present embodiment, the first electrode (10) may be referred to as a cathode, and the second electrode (20) may be referred to as an anode.

[0041] The first electrode (10) may include a first substrate (11) and a first active material layer (12) positioned 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, a copper alloy, a nickel alloy, or the like, and may be in the form of a thin plate or foam. The first active material layer (12) includes a negative electrode active material, and may optionally further include a binder and / or a conductive material.

[0042] In the first active material layer (12), the negative electrode active material may include at least one of a carbon-based active material, an alloy of lithium metal, and a silicon-carbon composite active material. The carbon-based negative electrode active material may include at least one of natural graphite and artificial graphite. The lithium metal alloy may be an alloy of lithium and 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 negative electrode active material, a second negative electrode active material, and a third negative electrode active material. The first negative electrode active material may include a plurality of silicon nanoparticles and an amorphous carbon coating layer positioned on the surfaces of the silicon nanoparticles. The second negative electrode active material may include a core comprising a silicon-carbon composite and a polymer coating layer positioned on the core. The third negative electrode active material may include a core comprising a silicon-based material and a carbon-based coating layer positioned on the core.

[0044] The second electrode (20) may include a second substrate (21) and a second active material layer (22) positioned on at least one surface of the second substrate (21). The second substrate (21) may be referred to as a positive electrode current collector, and the second active material layer (22) may be referred to as a positive electrode active material layer. The second substrate (21) may be made of aluminum or the like, and may be in the form of a thin plate or foam. The second active material layer (22) includes a positive electrode active material, and may optionally further include a binder 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, for example, at least one of a lithium-nickel-based oxide, a lithium-cobalt-based oxide, a lithium-manganese-based oxide, a lithium-iron phosphate-based compound, and a cobalt-free nickel-manganese-based oxide.

[0046] In each of the first active material layer (12) and the second active material layer (22), the binder may include at least one of an aqueous binder, a non-aqueous binder, and a dry binder. 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 a carbon-based material such as natural graphite, artificial graphite, carbon black, carbon fiber, carbon nanofiber, or carbon nanotube; a metal material in the form of metal powder or metal fiber including copper, nickel, aluminum, or silver; and a conductive polymer such as a polyphenylene derivative.

[0047] The separator (30) may be composed of a porous substrate or a porous substrate having a coating layer positioned on at least one surface. The porous substrate may include one or more of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester, polycarbonate, and polyimide. The coating layer may include a binder, and the binder may include a polyvinylidene fluoride-based compound. The separator (30) insulates the first electrode (10) and the second electrode (20) while allowing the movement of lithium ions.

[0048] In the first electrode (10), the first active material layer (12) may be positioned on the remaining portion except for one side (lower side) edge of the first substrate (11). The portion of the first substrate (11) that is not covered by the first active material layer (12) and has an exposed surface is referred to as a first non-coated portion (13). The first non-coated portion (13) may be referred to as a first substrate tab or a first electrode tab.

[0049] In the second electrode (20), the second active material layer (22) may be positioned on the remaining portion except for the other (upper) edge of the second substrate (21). The portion of the second substrate (21) that is not covered by the second active material layer (22) and has an exposed surface is referred to as a second non-coated portion (23). The second non-coated portion (23) may be referred to as a second substrate tab or a second electrode tab.

[0050] Each of the first unlined portion (13) and the second unlined portion (23) may include a pair of edge unlined portions (131, 231) and a central unlined portion (132, 232) positioned between the pair of edge unlined portions (131, 231). The height of the edge unlined portions (131, 231) measured along the width direction (W direction in FIG. 2) of the first electrode (10) and the second electrode (20) is smaller than the height of the central unlined portion (132, 232). Both sides of the central unlined portion (132, 232) may be diagonal, but are not limited to this example.

[0051] The central plain portion (132, 232) may be folded inward toward the winding center of the electrode assembly (100) so as to overlap with the central plain portion (132, 232) located inside. A plurality of cut lines may be positioned in the central plain portion (132, 232) to facilitate the folding of the central plain portion (132, 232). The plurality of cut lines may be formed in a diagonal direction, but are not limited to this example.

[0052] The central uncoated portion (132) is fixed to the first collector plate described later and functions to transfer the current of the first electrode (10) to the first collector plate. The central uncoated portion (232) is fixed to the second collector plate described later and functions to transfer the current of the second electrode (20) to the second collector plate. The central uncoated portions (132) that are bent inward and overlap each other are advantageous in increasing the current collection efficiency of the first electrode (10), and the central uncoated portions (232) that are bent inward and overlap each other are advantageous in 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 furthest from the winding center. The first end (15) and the second end (16) are located on opposite sides along the longitudinal direction (L direction in FIG. 2, winding direction in the winding state) of the first electrode (10). The first end (15) may be referred to as a leading end, and the second end (16) may be referred to as a terminal end. The first active material layer (12) is located in contact with the first end (15) and the second end (16).

[0054] A protective layer (40) is provided on at least one of the first end (15) and the second end (16) of the first electrode (10) to cover the end. FIG. 2 illustrates a case where the protective layer (40) is provided on 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 captures the constituent material of the first active material layer (12) so that the constituent material of the first active material layer (12) does not move to another location.

[0055] Fig. 4 is a partial plan view of the first electrode of the electrode assembly illustrated in Fig. 2. Fig. 5 is a cross-sectional view of the first electrode of the electrode assembly illustrated in Fig. 2.

[0056] Referring to FIGS. 4 and 5, the protective layer (40) includes a first protective layer (41) positioned to be in contact with the first surface (A10) of the first electrode (10), and a second protective layer (42) positioned to be in contact with the second surface (A20) of the first electrode (10). The first surface (A10) may be the inner surface of the first electrode (10) positioned toward 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). FIG. 4 illustrates the first surface of the first electrode (10).

[0057] A portion of the first protective layer (41) may overlap the first side (A10), and the remainder of the first protective layer (41) may be positioned to extend outward from the first end (15) or the second end (16). A portion of the second protective layer (42) may overlap the second side (A20), and the remainder of the second protective layer (42) may be positioned to extend outward from 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) and the length (L2) of the second protective layer (42) along the longitudinal direction (L direction) of the first electrode (10) may be different from each other. That is, the length (L1) of the first protective layer (41) may be greater than the length (L2) of the second protective layer (42), or the length (L2) of the second protective layer (42) may be greater than the length (L1) of the first protective layer (41). In FIGS. 4 and 5, a case in which the length (L2) of the second protective layer (42) is greater than the length (L1) of the first protective layer (41) is illustrated as an example.

[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 end (412) of the first protective layer (41) and the outer end (422) of the second protective layer (42) may be aligned with each other. That is, the outer end (412) of the first protective layer (41) and the outer end (422) of the second protective layer (42) may be positioned on a straight line along the thickness direction (T direction of FIG. 5) of the first electrode (10). On the other hand, the inner end (411) of the first protective layer (41) and the inner end (421) of the second protective layer (42) may be positioned to be offset from each other along the longitudinal direction (L direction) of the first electrode (10). The distance between the inner end (411) of the first protective layer (41) and the inner end (421) of the second protective layer (42) may be equal to the difference in length 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 an adhesive tape. The adhesive tape may be composed of a polymer film having an adhesive material applied to one surface, and may be composed of a film such as polyimide, polyethylene terephthalate, or polystyrene.

[0062] The first electrode (10) can be manufactured through a process in which a first active material layer (12) is formed on the first substrate (11) by a stripe coating method during the process in which a first substrate (11) in the shape of a stripe wound around a roller moves between the rollers, 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 manufactured through this cutting process.

[0063] During the process of cutting the first substrate (11) and the first active material layer (12), the constituent material of the first active material layer (12), for example, a negative electrode active material such as graphite, may fall off from the first active material layer (12). The negative electrode active material falling off from the first active material layer (12) may attach to a second electrode (20) of opposite polarity or flow into a location other than the first electrode (10) within the secondary battery. In this case, the output voltage of the secondary battery may decrease.

[0064] In the electrode assembly (100) of the present embodiment, the protective layer (50) can be applied to the first end (15) and the second end (16) immediately after the first end (15) and the second end (16) are created by cutting the first substrate (11) and the first active material layer (12), thereby covering the first end (15) and the second end (16). Therefore, even if the negative electrode active material falls off from the first active material layer (12) during the cutting process of the first substrate (11) and the first active material layer (12), the fallen negative electrode active material is captured by the protective layer (40) and does not move to any other location other than the first electrode (10).

[0065] The electrode assembly (100) of the present embodiment having a protective layer (40) can prevent the negative active material from being attached to the second electrode (20) or flowing into other places within the secondary battery, and can prevent a decrease in the output voltage of the secondary battery.

[0066] Fig. 6 is a partially enlarged cross-sectional view showing the central region of the electrode assembly illustrated in Fig. 1. Fig. 7 is a partially enlarged cross-sectional view showing the outer region of the electrode assembly illustrated in Fig. 1. For convenience, the illustration of the separator is omitted in Figs. 6 and 7.

[0067] Referring to FIGS. 6 and 7, a first electrode (10) having a protective layer (40) is wound together with a second electrode (20) with a separator in between to form an electrode assembly (100). At this time, the inner ends (411, 421) of the first protective layer (41) and the second protective layer (42) are positioned to be misaligned with each other along the winding direction, so that cracks in the electrode assembly (100) do not occur.

[0068] If the lengths of the first and second protective layers are the same, such that the inner ends of the first protective layer and the second protective layer coincide, a sudden change in thickness occurs at the inner ends of the first and second protective layers of the first electrode. In this case, stress may be concentrated at a portion of the first electrode that is in contact with the inner ends of the first and second protective layers or at a specific portion of the second electrode adjacent thereto, which may cause cracks to occur in the first or second electrode. The occurrence of cracks in the first or second electrode leads to damage to the electrode assembly.

[0069] In the electrode assembly (100) of the present embodiment, since the inner end (411) of the first protective layer (41) and the inner end (421) of the second protective layer (42) are positioned so as to be misaligned with each other along the winding direction, it is possible to suppress stress from being concentrated on a part of the first electrode (10) that is in contact with the inner end (411, 421) or a specific part of the second electrode (20) adjacent thereto. As a result, the protective layer (40) does not cause cracks to occur in the first electrode (10) or the second electrode (20), and damage to the electrode assembly (100) due to cracks can be prevented.

[0070] Meanwhile, the second active material layer (22) of the second electrode (20) may also be formed as a stripe coating on the second substrate (21) and then undergo a process of being cut together with the second substrate (21). However, since the constituent material of the second active material layer (22) does not easily fall off from the second active material layer (22), a protective layer may not be provided on the second electrode (20).

[0071] Referring again to FIG. 4, the first and second protective layers (41, 42) may be positioned at a distance from the central uncoated portion (132) along the longitudinal direction (L direction) of the first electrode (10). The first and second protective layers (41, 42) may cover a portion of the edge uncoated portion (131). In addition, the first and second protective layers (41, 42) may include extended portions (415, 425) extending to both sides (upper and lower sides) of the first electrode (10) along the width direction (W direction) of the first electrode (10).

[0072] The electrode assembly (100) may undergo volume changes such as expansion during the charging process and contraction during the discharging process, and such volume changes are mainly due to volume changes in the first active material layer (12). The expanded portion (415, 425) of the protective layer (40) prevents the first active material layer (12) and the second active material layer (22) from coming into contact with each other even when the first electrode (10) contracts, thereby suppressing the occurrence of a short circuit between the first electrode (10) and the second electrode (20).

[0073] The width (W1, W2) of the extension portion (415, 425) may fall within a preset reference range. The reference range may be approximately 1 mm to 3 mm, and as another example, approximately 1 mm to 2 mm. For example, the width (W1) of the extension portion (415, 425) extended downwardly from the first electrode (10) where the first non-conductive portion (13) is located may be approximately 1 mm to 2 mm, and the width (W2) of the extension portion (415, 425) extended upwardly from the first electrode (10) may be approximately 1 mm to 3 mm.

[0074] If the width (W1, W2) of the extension portion (415, 425) is smaller than the reference range, it may be difficult to implement the function of suppressing the occurrence of a short between the first electrode (10) and the second electrode (20). If the width (W1, W2) of the extension portion (415, 425) exceeds the reference range, the finishing quality of the electrode assembly (100) may deteriorate, and the protective layer (40) may interfere with other components of the secondary battery.

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

[0076] In the manufacturing process of the first electrode (10), it must be confirmed whether the width (W1, W2) of the extension portion (415, 425) falls within the standard range, and a first electrode in which the width (W1, W2) of the extension portion (415, 425) falls outside the standard range may be treated as defective. It is possible to confirm whether the width (W1, W2) of the extension portion (415, 425) falls within the standard range using a vision inspector (not shown), and for the accuracy of the vision inspection, the first protective layer (41) and the second protective layer (42) may have different colors.

[0077] The vision inspector can distinguish and measure the width (W1) of the expanded portion (415) of the first protective layer (41) and the width (W2) of the expanded 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 table below shows the detection error occurrence rate according to the color combination of the first protective layer (41) and the second protective layer (42).

[0078] Blue+RedBlue+YellowGreen+RedGreen+YellowTest Quantity50305030Detection Error Quantity0158Detection Error Rate(%)031030

[0079] From the results in the table above, it can be seen 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.

[0080] Fig. 8 is an exploded perspective view showing an unfolded state of an electrode assembly according to a second embodiment. Fig. 9 is a partial enlarged view of Fig. 8. Fig. 10 is a partial enlarged cross-sectional view of an electrode assembly according to a second embodiment. The electrode assembly of the second embodiment has the same or similar configuration as the first embodiment described above, except for the configuration described below.

[0081] Referring to FIGS. 8 to 10, in the electrode assembly of the present 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 collector plate described later in an unbent state, and the second uncoated portion (23) may be fixed to the second collector plate described later in an unbent state.

[0082] The first and second protective layers (41, 42) may cover the first non-conductive portion (13). In addition, the first and second protective layers (41, 42) may include an extension (415, 425) extending outwardly from the first active material layer (12) along the width direction (W direction) of the first electrode (10).

[0083] For example, the first active material layer (12) may include a third end (121) in contact with the first non-conductive 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 along the width direction (W direction) of the first electrode (10). The extension (415, 425) may be a portion that extends outwardly from the fourth end (122). The width (W3) of the extension (415, 425) may be the same as the width (W1, W3) of the extension described in the first embodiment, and a duplicate description will be omitted.

[0084] Fig. 11 is an exploded perspective view showing an unfolded state of an electrode assembly according to a third embodiment. The electrode assembly of the third embodiment has a configuration identical or similar to that of the second embodiment described above, except for the configuration described below.

[0085] Referring to Fig. 11, in the electrode assembly of the present embodiment, the protective layer (40) may not cover the first uncoated portion (13). That is, the protective layer (40) may overlap a portion of the first active material layer (12) excluding the first uncoated portion (13). The first uncoated portion (13) is fixed to a first current collecting plate, which will be described later, and functions to transmit the current of the first electrode (10) to the first current collecting plate. When the first uncoated portion (13) is not covered with the protective layer (40), the entire first uncoated portion (13) can make good contact with the first current collecting plate, thereby enhancing the current collecting effect.

[0086] Figure 12 is a process flow diagram showing a method for manufacturing an electrode assembly according to one embodiment.

[0087] Referring to FIG. 12, a method for manufacturing an electrode assembly according to the present embodiment includes the steps of forming a first active material layer by stripe coating on a first substrate, cutting the first substrate and the first active material layer to manufacture a first electrode (S10), separating two separated first electrodes (S20), introducing a first protective layer and a second protective layer so as to be in contact with the two first electrodes simultaneously (S30), cutting the center portions of the first and second protective layers (S40), and stacking and winding the first electrode, the separator, and the second electrode (S50).

[0088] Figures 13 and 14 are schematic diagrams illustrating process S10 of Figure 12. Figure 15 is a schematic diagram illustrating process S20 of Figure 12. Figure 16 is a schematic diagram illustrating process S30 of Figure 12. Figure 17 is a schematic diagram illustrating process S40 of Figure 12. Figure 18 is a schematic diagram illustrating process S50 of Figure 12.

[0089] Referring to Fig. 13, the first substrate (11) moves from the first roller (51) toward the second roller (52), and a coating device (60) may be placed on both sides (upper and lower sides) of the moving first substrate (11). The coating device (60) may continuously discharge the constituent materials of the first active material layer (12) onto both sides of the moving first substrate (11) to form the first active material layer (12). The first active material layer (12) includes a negative active material, and may optionally further include a binder and / or a conductive material.

[0090] Referring to FIGS. 14 and 15, the first substrate (11) and the first active material layer (12) can be cut by a cutter (71) to separate into two first electrodes (10) (S10). One of the two separated first electrodes (10) can be moved to separate the two first electrodes (10) from each other (S20).

[0091] A first protective layer injection device (81) and a second protective layer injection device (82) may be arranged on both sides (upper and lower sides) of two first electrodes (10) that are spaced apart from each other. An end of one of the two first electrodes (10) may be a first end (15), and an end of the other first electrode (10) may be a second end (16).

[0092] Referring to FIGS. 15 and 16, the first protective layer injection device (81) can inject the first protective layer (41) so as to contact the first surfaces (10A) of the two first electrodes (10) simultaneously, and the second protective layer injection device (82) can inject the second protective layer (42) so as to contact the second surfaces (10B) of the two first electrodes (10) simultaneously. The first protective layer (41) and the second protective layer (42) can be formed of a polymer film having an adhesive layer positioned on the 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).

[0093] The first protective layer (41) and the second protective layer (42) can be applied to the first end (15) and the second end (16) of the first electrode (10) immediately after the cutting process 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 falls off from the first active material layer (12) when the first active material layer (12) is cut, the fallen negative electrode active material can be captured by the first protective layer (41) and the second protective layer (42).

[0094] At this time, the first protective layer (41) and the second protective layer (42) may be provided with different lengths so that the end (411) of the first protective layer (41) and the end (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 end (411) of the first protective layer (41) and the end (421) of the second protective layer (42) may be positioned to be misaligned with each other along the longitudinal direction (L direction) of the first electrode (10).

[0095] As illustrated in FIG. 4, each of the first protective layer (41) and the second protective layer (42) may include an extension portion (415, 425), and it may be inspected using a vision inspection method whether the width (W1, W2) of the extension portion (415, 425) falls within a reference range. The device for vision inspection may include a camera and an image analysis unit, and the extension portion (415, 425) may be photographed using the camera, and the image analysis unit may analyze the image information to inspect whether the width (W1, W2) of the extension portion (415, 425) falls within a reference range.

[0096] To ensure the accuracy of the vision inspection, the first protective layer (41) and the second protective layer (42) may have different colors. For example, the first protective layer (41) and the second protective layer (42) may be composed of a combination of blue and red, which exhibits high detection accuracy. A first electrode whose width (W1, W2) of the extension (415, 425) exceeds the standard range may be treated as defective.

[0097] Referring to FIG. 5 and FIG. 17, the center portions of the first protective layer (41) and the second protective layer (42) can be cut by a cutter (72) to separate the protective layer (40) into two parts (S40). By cutting the protective layer (40), the outer ends (412, 422) of the first protective layer (41) and the second protective layer (42) can be positioned in a straight line along the thickness direction (T direction) of the first electrode (10). The ends (411, 421) of the first protective layer (41) and the second protective layer (42) that come into contact with the first active material layer (12) can be inner ends.

[0098] Referring to Fig. 18, a first electrode (10), a second electrode (20), and two separators (30) can form a laminate, and the laminate can be wound around a center pin (90). The laminate can be configured such that the second electrode (20), the separator (30), the first electrode (10), and the separator (30) are laminated in this order from the inner side facing the center pin (90). At this time, the positions of the first electrode (10) and the second electrode (20) can be exchanged. A protective layer (40) is positioned on at least one end of both ends of the first electrode (10).

[0099] The protective layer (40) captures the negative active material that has fallen off from the first active material layer (12) when the first active material layer (12) is cut, thereby preventing the negative active material from being attached to the second electrode (20) of the opposite polarity or from flowing into a location other than the first electrode (10) within the secondary battery. In addition, the different lengths of the first and second protective layers (41, 42) can suppress stress from being concentrated in a specific portion of the electrode assembly (100), and can prevent cracks from occurring in the electrode assembly (100).

[0100] Referring to FIG. 3, in the case of the electrode assembly of the first embodiment, during the process of winding the laminate (S50), the central plain portion (132) of the first plain portion (13) and the central plain portion (232) of the second plain portion (23) can be bent toward the winding center. For example, the central plain portions (132, 232) can be first bent toward the winding center of the electrode assembly by being pushed by high-pressure air during the winding process, and after winding the electrode assembly, they can be secondarily bent by being pressurized by a jig (not shown).

[0101] The central plain portion (132, 232) can be flattened to overlap with the portions located inside it through two folds. The folded central plain portion (132) can then be fixed to the first collector plate by a method such as laser welding. The folded central plain portion (232) can then be fixed to the second collector plate by a method such as laser welding.

[0102] Fig. 19 is a perspective view of a secondary battery according to one embodiment. Fig. 20 is a cross-sectional view of the secondary battery illustrated in Fig. 19. Fig. 21 is a cross-sectional view showing a modified example of the secondary battery illustrated in Fig. 20.

[0103] Referring to FIGS. 19 to 21, the secondary battery (1000, 2000) of the present embodiment may include a cylindrical case (200), an electrode assembly (100) accommodated inside the case (200), a terminal portion (300) provided on one side (upper side) of the case (200), and a cap plate (400) provided on the other side (lower side) of the case (200).

[0104] The electrode assembly (100) is an electrode assembly according to any one of the first to third embodiments described above. The electrode assembly (100) of FIG. 20 is an electrode assembly according to the first embodiment described above, and the electrode assembly (100) of FIG. 21 is an electrode assembly according to the second or third embodiment described above.

[0105] The first uncoated portion of the first electrode (10) may be fixed to the first collector plate (510) and electrically connected to the first collector plate (510). The second uncoated portion of the second electrode (20) may be fixed to the second collector plate (520) and electrically connected to the second collector plate (520). The first collector plate (510) and the second collector plate (520) may be positioned on opposite sides. The electrode assembly (100) and the first collector plate (510) and the second collector plate (520) may be accommodated inside the case (200) together with the electrolyte.

[0106] The case (200) may include a disc-shaped upper surface (210) and a cylindrical side surface (220) extending downward from the edge of the upper surface (210). The case (200) may have a cylindrical shape with a closed upper surface and an open lower surface. The case (200) may be composed of, for example, steel, a steel alloy, aluminum, an aluminum alloy, etc. When the upper and lower surfaces of the secondary battery (1000, 2000) are reversed, the upper surface (210) may be referred to as a bottom surface.

[0107] A terminal hole may be located at the center of the upper surface (210), and a terminal portion (300) may be installed in the terminal hole. The terminal portion (300) may include a first terminal (310) having a circular shape, a second terminal (320) having a roughly cylindrical shape, and first to third insulators (330, 340, 350). The first terminal (310) may be referred to as a terminal plate, and the second terminal (320) may be referred to as a rivet terminal. The first terminal (310) may be disposed on the outside of the upper surface (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 (210) by riveting.

[0108] The second terminal (320) can be coupled to the second collector plate (520), and the first terminal (310) and the second terminal (320) can maintain the same polarity as the second collector plate (520). That is, the first terminal (310) and the second terminal (320) can be charged with the same polarity as the second electrode (20) of the electrode assembly (100) by the second collector plate (520), and can function as a positive terminal.

[0109] The first insulator (330) may be positioned between the upper surface (210) and the first terminal (310) on the outer side of the upper surface (210). The second insulator (340) may surround the second terminal (320) and be positioned between the second terminal (320) and the upper surface (210). The third insulator (350) may be positioned between the upper surface (210) and the second current collector (520) on the inner side of the upper surface (210). The first to third insulators (330, 340, 350) may insulate the case (200) and the first and second terminals (310, 320).

[0110] Optionally, an insulating cover (600) may be additionally placed between the third insulator (350) and the second collector plate (520). The insulating cover (600) may cover a portion of the upper surface of the second collector plate (520) and may be extended 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 collector plate (520) from contacting the case (200) and conducting current.

[0111] A beading portion (230) and a crimping portion (240) may be positioned on the side (220) of the case (200). The beading portion (230) may be positioned adjacent to the lower end of the side (220) and may be a portion that is concavely deformed toward the inside of the case (200). The lower end of the side (220) spaced apart from the beading portion (230) may be bent toward the inside of the case (200) to become the crimping portion (240).

[0112] The first collector plate (510) may include a plate-shaped portion (511) having a circular shape and a connecting portion (512) extending downward from an edge of the plate-shaped portion (511). The connecting portion (512) may be in close contact with the inner surface of the beading portion (230). Accordingly, the first collector plate (510) and the case (200) may be electrically connected. The case (200) may be charged with the same polarity as the first electrode (10) of the electrode assembly (100) by the first collector plate (510) and may function as a negative terminal.

[0113] On the other hand, although the city is omitted, the first collector plate can be coupled with the first terminal and the second terminal so that the first terminal and the second terminal can function as a negative terminal, and the second collector plate can be in contact with the case so that the case can function as a positive terminal.

[0114] The cap plate (400) can be positioned on the outer side (lower side) of the first collector plate (510) and can be fixed between the beading portion (230) and the crimping portion (240) via an insulating gasket (700). The cap plate (400) can seal the case (200) and can be electrically non-polar by being insulated from the first electrode (10), the second electrode (20) and the case (200).

[0115] A notch groove (410) may be positioned on at least one surface of the cap plate (400). The notch groove (410) may have a V-shaped cross-section, and may be an arc shape on a plane (when the target object is viewed from above). The internal temperature of the secondary battery (1000, 2000) may rise due to various reasons such as rapid charging / discharging, external impact, exposure to a high temperature environment, etc., and the internal pressure may rise due to vaporization of the electrolyte, etc. When the internal pressure of the secondary battery (1000, 2000) rises, the cap plate (400) may break from the notch groove (410), thereby releasing internal gas.

[0116] In the secondary battery (1000, 2000) of the aforementioned configuration, the negative active material is prevented from flowing into a location other than the first electrode (10) due to the protective layer (40) (see FIG. 2) provided on the first electrode (10). Therefore, the secondary battery (1000, 2000) of the present embodiment can prevent a decrease in output voltage due to the negative active material flowing into a location other than the first electrode (10).

[0117] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Separator; First electrode and second electrode laminated and wound with the above separator between them; A protective layer covering at least one end of the first electrode in the winding direction, The protective layer includes a first protective layer positioned to be in contact with one surface of the first electrode, and a second protective layer positioned to be in contact with the other surface of the first electrode and the first protective layer. An electrode assembly in which an end of the first protective layer positioned on the one surface and an end of the second protective layer positioned on the other surface are positioned at a distance from each other along the winding direction.

2. In paragraph 1, A portion of the first protective layer overlaps the first electrode, and the remainder of the first protective layer extends outward from the end of the first electrode, An electrode assembly wherein a portion of the second protective layer overlaps the first electrode, and the remainder of the second protective layer extends outward from an end of the first electrode and is in contact with the remainder of the first protective layer.

3. In paragraph 2, An electrode assembly in which each of the first protective layer and the second protective layer is composed of a polymer film having an adhesive material applied to one surface facing each other.

4. In paragraph 1, The first electrode includes a substrate, an active material layer positioned on at least one surface of the substrate, and a non-conductive portion positioned on one edge of the substrate. An electrode assembly in which the above active material layer includes a negative active material and is positioned in contact with both ends of the substrate.

5. In paragraph 4, An electrode assembly wherein each of the first protective layer and the second protective layer includes an extension portion extending outwardly of the first electrode along the width direction of the first electrode.

6. In paragraph 5, An electrode assembly wherein the first protective layer and the second protective layer have different colors.

7. In paragraph 5, The above-mentioned plain portion includes a pair of edge plain portions in contact with both ends of the above-mentioned substrate, and a central plain portion located between the pair of edge plain portions, The above protective layer is an electrode assembly positioned at a distance from the central non-conductive portion along the above winding direction.

8. In paragraph 7, The above protective layer overlaps the active material layer and the edge non-conductive portion, The above extension portion is an electrode assembly that extends outside on both sides of the first electrode.

9. In paragraph 5, The above-mentioned blank area has a certain width, The protective layer overlaps the active material layer and the non-conductive portion, The above-mentioned extension portion is an electrode assembly located on the opposite side of the non-conductive portion along the width direction of the first electrode.

10. In paragraph 5, The above-mentioned blank area has a certain width, The above protective layer overlaps the above active material layer, The above-mentioned extension portion is an electrode assembly located on the opposite side of the non-conductive portion along the width direction of the first electrode.

11. An active material layer is formed by stripe coating on a substrate, and the substrate and the active material layer are cut to form a first electrode; Separating the two first electrodes by cutting; The first protective layer and the second protective layer are introduced so as to be in contact with the two first electrodes simultaneously, and the protective layer is manufactured by cutting the middle part of the first protective layer and the second protective layer; The first electrode, the separator, and the second electrode are laminated and wound; A method for manufacturing an electrode assembly in which the first protective layer and the second protective layer introduced in the process of manufacturing the protective layer have different lengths.

12. In paragraph 11, A method for manufacturing an electrode assembly, wherein the above active material layer includes a negative active material and is positioned on both sides of the substrate.

13. In paragraph 11, A method for manufacturing an electrode assembly in which the first protective layer is inserted so as to be in contact with one side of the two first electrodes at the same time, the second protective layer is inserted so as to be in contact with the other side of the two first electrodes at the same time, and the first protective layer and the second protective layer are in contact with each other at the center portion.

14. In paragraph 13, A method for manufacturing an electrode assembly, wherein the first protective layer and the second protective layer are formed of a polymer film having an adhesive material applied to one surface facing each other.

15. In paragraph 11, Each of the first protective layer and the second protective layer includes an extension extending outward from the first electrode along the width direction of the first electrode, A method for manufacturing an electrode assembly, wherein a vision inspection method is used during the process of manufacturing the above protective layer to check whether the width of the extended portion falls within a standard range.

16. In paragraph 15, A method for manufacturing an electrode assembly, wherein the first protective layer and the second protective layer have different colors.

17. An electrode assembly comprising a separator, first and second electrodes laminated and wound with the separator interposed therebetween, and a protective layer covering at least one end of both ends of the first electrode along the winding direction; A case that accommodates the electrode assembly in an internal space; and A cap plate is included that is coupled to an end of the case and seals the case, 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, A secondary battery in which an end of the first protective layer positioned on the one surface and an end of the second protective layer positioned on the other surface are positioned at a distance from each other along the winding direction.

18. In paragraph 17, The first electrode includes a first active material layer having a negative active material, A secondary battery in which the first active material layer is positioned in contact with both ends of the first electrode.

19. In paragraph 18, Each of the first protective layer and the second protective layer includes an extension extending outward from the first electrode along the width direction of the first electrode, A secondary battery wherein the first protective layer and the second protective layer have different colors.

Images