Electrode assembly and rechargeable battery having the same

Abstract

Disclosed are an electrode assembly and a rechargeable battery having the same. The electrode assembly includes a separator, a positive electrode, and a negative electrode positioned such that the separator is wound between and together with the positive electrode and the negative electrode. The negative electrode includes a negative electrode substrate, a first active material layer on a first surface of the negative electrode substrate, and a second active material layer on a second surface of the negative electrode substrate. A plurality of first recesses are formed in the first active material layer. A plurality of second grooves are formed in the second active material layer, and the plurality of first grooves and the plurality of second grooves have different patterns.

Description

Technical Field

[0001] This disclosure relates to a rechargeable battery, and to a rechargeable battery having a wound electrode assembly. Background Technology

[0002] Rechargeable batteries are used for a variety of purposes, including as a power source for small electronic devices such as mobile phones and laptops, and as a power source for motors used to drive electric vehicles and hybrid vehicles, for example. A rechargeable battery includes an electrode assembly and a casing that houses and seals the electrode assembly and electrolyte within an internal space. The electrode assembly includes two electrodes (a positive electrode and a negative electrode) and a separator.

[0003] To increase the output and capacity of rechargeable batteries, increasing the energy density and loading level of the electrodes may be advantageous. However, electrodes developed in this way may have the unintended side effect of reducing the impregnation of the electrolyte. When the impregnation of the electrolyte in the electrode is reduced, precipitation may begin in areas of insufficient electrolyte impregnation, which may reduce the life characteristics of the rechargeable battery. Summary of the Invention

[0004] This disclosure describes an electrode assembly and a rechargeable battery including the electrode assembly, which improves lifetime characteristics by increasing the energy density and load level of the electrode while improving the impregnation of the electrolyte.

[0005] An electrode assembly according to an example embodiment includes a separator, a positive electrode, and a negative electrode, the positive and negative electrodes being positioned such that the separator is wound between and with the separator. The negative electrode includes a negative electrode substrate, a first active material layer on a first surface of the negative electrode substrate, and a second active material layer on a second surface of the negative electrode substrate. A plurality of first grooves are formed in the first active material layer. A plurality of second grooves are formed in the second active material layer, the plurality of second grooves having a different pattern from the plurality of first grooves.

[0006] The first surface may face the interior of the electrode assembly, and a plurality of first grooves may be arranged in a dot pattern. The plurality of first grooves may be arranged in a circular dot pattern, and each or one or more of the plurality of first grooves may have a width that decreases with decreasing distance from the negative electrode substrate. The width of each or one or more of the plurality of first grooves may be in the range of approximately 20 μm to 60 μm. The depth of each or one or more of the plurality of first grooves may be in the range of approximately 30 μm to 70 μm. The density of the plurality of first grooves may be approximately 100 EA / mm². 2 Up to 450EA / mm 2 Within the range.

[0007] The second surface may face the exterior of the electrode assembly, and the plurality of second grooves may be positioned in a line pattern. The plurality of second grooves may be positioned parallel to the width direction of the negative electrode and spaced apart from each other in the length direction of the negative electrode. The width of each or more of the plurality of second grooves may be greater than the depth of each or more of the plurality of second grooves. Each or more of the plurality of second grooves may have a constant or substantially constant width in the thickness direction of the negative electrode. The width of each or more of the plurality of second grooves may be in the range of approximately 40 μm to 70 μm. The depth of each or more of the plurality of second grooves may be in the range of approximately 10 μm to 30 μm.

[0008] An electrode assembly according to another example embodiment includes a separator and positive and negative electrodes, the positive and negative electrodes being positioned such that the separator is wound between and together with the separator. The negative electrode includes a negative electrode substrate, a first active material layer on an inner surface of the negative electrode substrate, and a second active material layer on an outer surface of the negative electrode substrate. A plurality of first grooves are formed in the first active material layer. A plurality of second grooves are formed in the second active material layer, the plurality of second grooves having a different pattern from the plurality of first grooves. The area of ​​the surface region exposed by the plurality of second grooves in the second active material layer is larger than the area of ​​the surface region exposed by the plurality of first grooves in the first active material layer.

[0009] Multiple first grooves can be positioned in a dot pattern, and multiple second grooves can be positioned in a line pattern. Multiple first grooves can also be positioned in a dot pattern, and each or one or more of the multiple first grooves can have a width that decreases with decreasing distance from the negative electrode substrate. The width of each or one or more of the multiple first grooves can be in the range of approximately 20 μm to 60 μm. The depth of each or one or more of the multiple first grooves can be in the range of approximately 30 μm to 70 μm, and the density of the multiple first grooves can be approximately 100 EA / mm². 2 Up to 450EA / mm 2 Within the range.

[0010] Multiple second grooves can be positioned in a line pattern parallel to the width direction of the negative electrode and can be spaced apart from each other in the length direction of the negative electrode. The width of each or more of the multiple second grooves can be greater than their depth. Each or more of the multiple second grooves can have a constant or substantially constant width in the thickness direction of the negative electrode. The width of each or more of the multiple second grooves can be in the range of approximately 40 μm to 70 μm, and the depth of each or more of the multiple second grooves can be in the range of approximately 10 μm to 30 μm.

[0011] The negative electrode may include a flat portion and a curved portion. A plurality of first grooves and a plurality of second grooves may be located at least in the curved portion. The plurality of first grooves and the plurality of second grooves may be positioned throughout the flat and curved portions.

[0012] The rechargeable battery according to the example embodiment includes an electrode assembly having the above-described configuration and a housing that contains and seals the electrode assembly and electrolyte within an internal space.

[0013] The electrode assembly can be wound around two axes of rotation and includes a central portion and a pair of curved portions located on either side of the central portion. A plurality of first grooves and a plurality of second grooves can be positioned corresponding to at least one pair of curved portions. Alternatively, the electrode assembly can be wound around one axis of rotation. A plurality of first grooves can be positioned throughout a first active material layer, and a plurality of second grooves can be positioned throughout a second active material layer.

[0014] According to the example embodiments, by forming a desired or optimal groove pattern in the negative electrode active material layer, the impregnation of the electrolyte can be improved and the formation of deposits in the negative electrode can be reduced or suppressed. The rechargeable battery according to the example embodiments can improve long-term life characteristics while maintaining a high initial discharge capacity. Attached Figure Description

[0015] Figure 1 This is a perspective view of the electrode assembly according to the first example embodiment.

[0016] Figure 2 yes Figure 1 A partial enlarged view of the electrode assembly shown.

[0017] Figure 3 yes Figure 1 A schematic cross-sectional view of the electrode assembly shown.

[0018] Figure 4 It shows the negative electrode. Figure 3 A magnified view of a portion of the image.

[0019] Figure 5 yes Figure 4 A partially enlarged top view of the first active material layer of the negative electrode shown.

[0020] Figure 6 yes Figure 4 A partially enlarged top view of the second active material layer of the negative electrode shown.

[0021] Figure 7 This is an enlarged cross-sectional view of the negative electrode in the electrode assembly according to the second example embodiment.

[0022] Figure 8 This is a perspective view of the electrode assembly according to a third example embodiment.

[0023] Figure 9 This is a perspective view of the electrode assembly according to the fourth example embodiment.

[0024] Figure 10 yes Figure 9 A cross-sectional view of the electrode assembly shown.

[0025] Figure 11 It shows the negative electrode. Figure 9 A partially enlarged sectional view.

[0026] Figure 12 This is an exploded perspective view of a rechargeable battery according to an example embodiment.

[0027] Figure 13 This is a perspective view of a rechargeable battery according to another example embodiment.

[0028] Figure 14 yes Figure 13 The cross-sectional view of the rechargeable battery shown.

[0029] Figure 15 This is a perspective view of a rechargeable battery according to another example embodiment.

[0030] Figure 16 yes Figure 15 The cross-sectional view of the rechargeable battery shown.

[0031] Figure 17 It is a graph showing the lifespan characteristics of a rechargeable battery of an example embodiment and rechargeable batteries of Comparative Example 1 and Comparative Example 2. Detailed Implementation

[0032] This disclosure is described in detail below with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are depicted. As those skilled in the art will recognize, the described exemplary embodiments can be modified in various ways without departing from the spirit or scope of this disclosure.

[0033] When the terms “about,” “approximately,” or “substantially” are used in conjunction with numerical values ​​in this specification, the relevant numerical values ​​are intended to include a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0034] Figure 1 This is a perspective view of the electrode assembly according to the first example embodiment. Figure 2 yes Figure 1 A partial enlarged view of the electrode assembly shown. Figure 3 yes Figure 1A schematic cross-sectional view of the electrode assembly shown.

[0035] Reference Figures 1 to 3 The electrode assembly 100 of the example embodiment can be constructed as a stack including a positive electrode 10, a negative electrode 20 and two diaphragms 30 wound multiple times.

[0036] Each of the positive electrode 10, negative electrode 20, and two diaphragms 30 can be manufactured in an elongated shape. The laminate can have a configuration in which, for example, the negative electrode 20, diaphragm 30, positive electrode 10, and diaphragm 30 are stacked in this order. The laminate can be wound around two rotation axes AX1, AX2, and the electrode assembly 100 can have a flat core shape.

[0037] In terms of appearance, the electrode assembly 100 may include a flat quadrilateral central portion 41 and a pair of curved portions 42 located on either side of the central portion 41. The central portion 41 may be a flat portion of a given or desired thickness located between the two rotation axes AX1, AX2. The pair of curved portions 42 may be semi-circular curved portions surrounding each of the two rotation axes AX1, AX2.

[0038] The positive electrode 10 may include a positive electrode substrate 11 and a pair of positive electrode active material layers 12 and 13 located on two surfaces of the positive electrode substrate 11. The negative electrode 20 may include a negative electrode substrate 21 and a pair of negative electrode active material layers 22 and 23 located on two surfaces of the negative electrode substrate 21. A separator 30 is located between the positive electrode 10 and the negative electrode 20 to physically separate the positive electrode 10 and the negative electrode 20.

[0039] The positive electrode substrate 11 may include a thin metal sheet, such as aluminum foil or aluminum mesh, having a desired or improved conductivity. The positive electrode active material layers 12 and 13 may include positive electrode active material and may also include binders and / or conductive materials. The positive electrode substrate 11 forms a path for the movement of charges generated in the positive electrode active material layers 12 and 13 and supports the positive electrode active material layers 12 and 13. The positive electrode substrate 11 may be referred to as a positive electrode current collector.

[0040] The positive electrode active material may include lithium transition metal complex oxides. Lithium transition metal complex oxides may include at least one of, for example, lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compounds, and cobalt-free lithium nickel manganese oxide.

[0041] The negative electrode substrate 21 may include a thin metal sheet having a desired or improved electrical conductivity, such as, for example, at least one of a copper foil, a copper mesh, a nickel foil, and a nickel mesh. The negative electrode active material layers 22 and 23 may include a negative electrode active material and may further include a binder and / or a conductive material. The negative electrode substrate 21 constitutes a path for the movement of charges generated in the negative electrode active material layers 22 and 23 and supports the negative electrode active material layers 22 and 23. The negative electrode substrate 21 may be referred to as a negative electrode current collector.

[0042] The negative electrode active material may include at least one of a carbon-based active material and a silicon-based active material. The carbon-based active material may include at least one of natural graphite and artificial graphite. The silicon-based active material may include at least one of a silicon-carbon composite material, silicon oxide (SiO x , 0 < x ≤ 2), and silicon carbide (SiC).

[0043] In each or one or more of the positive electrode active material layers 12 and 13 and the negative electrode active material layers 22 and 23, the binder may include at least one of an aqueous binder, a non-aqueous binder, and a dry binder. In each or one or more of the positive electrode active material layers 12 and 13 and the negative electrode active material layers 22 and 23, the conductive material may include at least one of the following: carbon-based materials, such as natural graphite, artificial graphite, carbon black, carbon fiber, carbon nanofiber, and carbon nanotube; metal materials in the form of metal powder or metal fiber, including at least one of copper, nickel, aluminum, and silver; and conductive polymers, such as polyphenylene derivatives.

[0044] The separator 30 may include a porous substrate or a porous substrate having a coating layer on at least one of its surfaces. 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.

[0045] The positive electrode 10 may include at least one positive electrode tab 15, and the negative electrode 20 may include at least one negative electrode tab 25. The positive electrode tab 15 and the negative electrode tab 25 may extend toward one side of the electrode assembly 100. On the other hand, when the positive electrode tab 15 extends toward one side of the electrode assembly, the negative electrode tab 25 may extend toward the other side of the electrode assembly. Figure 1 The first case is shown as an example.

[0046] In Figure 3 , the illustration of the separator is omitted for convenience. In Figure 3In the electrode assembly 100 shown, the negative electrode 20 can be positioned closer to the interior (winding center) of the electrode assembly 100 than the positive electrode 10. The negative electrode 20 can be located at the outermost part of the electrode assembly 100, at least one turn longer than the positive electrode 10.

[0047] The negative electrode substrate 21 may include a first surface positioned toward the interior of the electrode assembly 100 and a second surface positioned toward the exterior of the electrode assembly 100. A pair of negative electrode active material layers 22, 23 may include a first active material layer 22 located on the first surface and a second active material layer 23 located on the second surface.

[0048] The negative electrode substrate 21 may include a first end 21a and a second end 21b disposed at both ends in the length direction (winding direction). The first end 21a may be the end on the side where winding begins and may be located at the innermost part of the electrode assembly 100. The second end 21b may be the end on the side where winding ends and may be located at the outermost part of the electrode assembly 100.

[0049] The first active material layer 22 can be located at a predetermined or desired distance from the first end 21a. For example, the first active material layer 22 can be positioned at a distance from the first end 21a that corresponds to a circle of the negative electrode substrate 21 starting from the first end 21a. Since the portion of the first surface of the negative electrode substrate 21 corresponding to the circle starting from the first end 21a does not face the positive electrode 10, the first active material layer 22 may not be located in this portion.

[0050] The second active material layer 23 can be located at a predetermined distance from the second end 21b. For example, the second active material layer 23 can be positioned at a distance from the second end 21b that corresponds to a circle of the negative electrode substrate 21 starting from the second end 21b. Since the portion of the second surface of the negative electrode substrate 21 that corresponds to approximately one circle inward from the second end 21b does not face the positive electrode 10, the second active material layer 23 may not be located in this portion.

[0051] Figure 3 The electrode assembly 100 shown is merely an example, and the electrode assembly 100 of this example embodiment may have other than Figure 3 Various constructions other than those shown.

[0052] The electrode assembly 100 can be housed together with the electrolyte within the interior space of a housing (not shown). The electrolyte is a medium configured to allow lithium ions to move between the positive electrode 10 and the negative electrode 20, and may include at least one of a lithium salt, an organic solvent, and an additive. The membrane 30 contains the electrolyte due to its porous structure and allows lithium ions to pass through.

[0053] During the charging process, lithium ions are deintercalated from the positive electrode active material layers 12 and 13 and intercalated into the negative electrode active material layers 22 and 23. During the discharging process, lithium ions are deintercalated from the negative electrode active material layers 22 and 23 and intercalated into the positive electrode active material layers 12 and 13. The electrode assembly 100 can be configured to perform stable charging and discharging functions when the positive electrode 10, the negative electrode 20, and the separator 30 are fully immersed in the electrolyte.

[0054] Figure 4 It shows the negative electrode. Figure 3 A magnified view of a portion of the image. Figure 5 yes Figure 4 A partially enlarged top view of the first active material layer of the negative electrode shown. Figure 6 yes Figure 4 A partially enlarged top view of the second active material layer of the negative electrode shown.

[0055] Reference Figures 4 to 6 The first active material layer 22 and the second active material layer 23 can be made of materials with high energy density and can have a thickness in the range of about 70 μm or greater and a density of about 10 mg / cm³. 2 Or a wider range of load levels. Load level represents the weight per unit area.

[0056] Typically, silicon-based active materials have an energy density approximately 10 times higher than that of carbon-based active materials; however, silicon-based active materials exhibit large volume changes during charging and discharging. The first active material layer 22 and the second active material layer 23 may comprise, for example, silicon-based and carbon-based active materials in an appropriate or desired ratio to increase energy density while reducing volume changes.

[0057] The first active material layer 22 and the second active material layer 23 can increase the output and capacity of the rechargeable battery by ensuring the aforementioned thickness and load level. The first active material layer 22 and the second active material layer 23 may have a rough surface structure to increase the impregnation of the electrolyte. Typically, as the thickness, packing density, and load level of the negative electrode active material layer increase, the impregnation of the electrolyte may decrease.

[0058] The first active material layer 22 may include a plurality of first grooves 51, and the second active material layer 23 may include a plurality of second grooves 52. The plurality of first grooves 51 extend across the first active material layer 22 and increase the surface area of ​​the first active material layer 22, and the plurality of second grooves 52 extend across the second active material layer 23 and increase the surface area of ​​the second active material layer 23. The plurality of first grooves 51 and the plurality of second grooves 52 provide impregnation paths for the electrolyte and are configured to increase the rate of electrolyte permeation.

[0059] The first active material layer 22 and the second active material layer 23, due to their rough surface structure, can improve the impregnation of the electrolyte and perform more stable charging and discharging functions. In this case, the plurality of first grooves 51 and the plurality of second grooves 52 can be formed in different patterns. For example, the plurality of first grooves 51 and the plurality of second grooves 52 can be formed in a desired or optimal pattern that matches the positional characteristics of the first active material layer 22 and the second active material layer 23 to improve or maximize the function of the negative electrode active material layers 22, 23.

[0060] By winding the electrode assembly 100, the area where the second active material layer 23 and the positive electrode 10 face each other is larger than the area where the first active material layer 22 and the positive electrode 10 face each other. Therefore, during charging and discharging processes, lithium-ion insertion and extraction may occur more actively in the second active material layer 23 than in the first active material layer 22. This can be seen as the second active material layer 23 being slightly more demanding to use compared to the first active material layer 22.

[0061] Multiple first grooves 51 can be formed as a dot pattern and can be spaced apart from each other on the surface of the first active material layer 22. For example, the multiple first grooves 51 can be formed by or include dots, and can be arranged at equal distances in a first direction (X-axis direction) and a second direction (Y-axis direction) that are orthogonal to each other. The first direction (X-axis direction) can be the length direction of the negative electrode 20, and the second direction (Y-axis direction) can be the width direction of the negative electrode 20.

[0062] The multiple first grooves 51 can be formed into various shapes other than dots, such as polygonal dots or elliptical dots. Figure 5 The image shows an example of a plurality of first grooves 51 including dots. The plurality of first grooves 51 can be manufactured using various methods such as needle punching or laser processing. The plurality of first grooves 51 can be manufactured during the manufacturing process to have substantially the same width and substantially the same depth.

[0063] The depth of the first groove 51 can be less than the thickness of the first active material layer 22. The depth of the first groove 51 can be greater than the width of the first groove 51, but is not limited thereto. The first groove 51 can have a constant width or a varying width in the third direction (Z-axis direction). In the central portion 41, the third direction (Z-axis direction) can be the thickness direction of the negative electrode 20.

[0064] For example, when the first groove 51 is manufactured by needle punching, the first groove 51 can have a varying width in the third direction (Z-axis direction). When the first groove is manufactured by laser processing, the first groove can have a constant width in the third direction. Figure 4The image shows an example where the width of the first groove 51 decreases as the distance from the negative electrode substrate 21 decreases.

[0065] Multiple second grooves 52 can be formed as a line pattern and can be spaced apart from each other on the surface of the second active material layer 23. The multiple second grooves 52 can be formed as a line pattern parallel to the second direction (Y-axis direction) and can be spaced apart from each other at a certain distance in the first direction (X-axis direction) (e.g., equidistant). When the second grooves 52 are parallel to the second direction (Y-axis direction), the width of the second grooves 52 can be increased at the curved portion 42.

[0066] The plurality of second grooves 52 can be manufactured by various methods, such as by needle punching or laser processing. The plurality of second grooves 52 can be manufactured during the manufacturing process to have substantially the same width and substantially the same depth. The depth of the second grooves 52 can be less than the thickness of the second active material layer 23. The width of the second grooves 52 can be greater than the depth of the second grooves 52, but is not limited thereto.

[0067] The second groove 52 can have a constant or varying width in the third direction (Z-axis direction). For example, when the second groove is manufactured by needle punching, the second groove can have a varying width in the third direction (Z-axis direction). When the second groove 52 is manufactured by laser processing, the second groove 52 can have a constant width in the third direction (Z-axis direction). Figure 4 The image shows an example of a second groove 52 having a constant or substantially constant width.

[0068] The width of the first groove 51 located at the curved portion 42 may be different from the width of the first groove 51 located at the center portion 41. Since the first active material layer 22 is curved inward at the curved portion 42, the width of the first groove 51 located at the curved portion 42 may be smaller than the width of the first groove 51 located at the center portion 41.

[0069] The width of the second groove 52 located at the curved portion 42 can be different from the width of the second groove 52 located at the central portion 41. Since the second active material layer 23 bends outward at the curved portion 42, the width of the second groove 52 located at the curved portion 42 can be greater than the width of the second groove 52 located at the central portion 41. The enlarged width of the second groove 52 at the curved portion 42 can further widen the electrolyte impregnation path and increase the electrolyte impregnation speed.

[0070] Due to the difference in the patterns of the first groove 51 and the second groove 52, the area (or size) of the surface region exposed by the plurality of second grooves 52 in the second active material layer 23 (e.g., the area occupied by the plurality of second grooves 52) can be greater than the area (or size) of the surface region exposed by the plurality of first grooves 51 in the first active material layer 22 (e.g., the area occupied by the plurality of first grooves 51). In other words, the surface area of ​​the second active material layer 23 per unit area of ​​the negative electrode substrate 21 can be greater than the surface area of ​​the first active material layer 22 per unit area of ​​the negative electrode substrate 21.

[0071] The electrode assembly 100 of this example embodiment can increase the surface area of ​​the second active material layer 23, which is used in a slightly more demanding manner than the first active material layer 22, to be greater than the surface area of ​​the first active material layer 22. Therefore, through the reaction with the positive electrode 10 throughout the second active material layer 23, lithium ion insertion and extraction can be promoted, and the formation of precipitates can be effectively reduced or suppressed in the second active material layer 23.

[0072] Typically, due to the strong tensile forces generated during the winding process, the bent portions of the electrode assembly may have lower electrolyte impregnation than the central portions, resulting in deposits potentially forming more easily at the bent portions.

[0073] The electrode assembly 100 of this example embodiment can increase the width of the second groove 52 at the bend 42 by using the line pattern of the second groove 52, and by using the second groove 52, the impregnation path of the electrolyte at the bend 42 can be widened, while simultaneously increasing the electrolyte impregnation rate. Therefore, the impregnation properties of the second active material layer 23 at the bend 42 can be improved, and the formation of precipitates at the bend 42 can be effectively reduced or suppressed.

[0074] In the electrode assembly 100 constructed as described above, for example, the width (diameter) of the first groove 51 can be in the range of approximately 20 μm to 60 μm, and the depth of the first groove 51 can be in the range of approximately 30 μm to 70 μm. The density of the plurality of first grooves 51 can be approximately 100 EA / mm². 2 Up to 450EA / mm 2 Within the range. Here, EA represents the number of grooves.

[0075] When the width (diameter) of the first groove 51 is less than about 20 μm, or the depth of the first groove 51 is less than about 30 μm, or when the density of the plurality of first grooves 51 is less than about 100 EA / mm 2 At that time, the effect of increasing the surface area of ​​the first active material layer 22 may be insufficient, and therefore the effect of improving the impregnation of the electrolyte may be low.

[0076] When multiple first grooves 51 are generated by needle punching, the width (diameter) of the first groove 51 exceeds approximately 60 μm, the depth of the first groove 51 exceeds approximately 70 μm, or the density of the multiple first grooves 51 exceeds approximately 450 EA / mm². 2 As the punching process is repeated, the rigidity of the needle decreases, so the needle may break during the process of creating multiple first grooves 51, which may result in a defective pattern of the first grooves 51.

[0077] When multiple first grooves 51 are generated by laser irradiation, if the width (diameter) of the first groove 51 exceeds approximately 60 μm, or the depth of the first groove 51 exceeds approximately 70 μm, or the density of the multiple first grooves 51 exceeds approximately 450 EA / mm 2 At this time, the active material may be significantly or excessively removed by the laser, resulting in a decrease in the loading level of the first active material layer 22.

[0078] The width of the second groove 52 can be greater than the depth of the second groove 52. As the depth of the second groove 52 increases, a high-power laser must be used for repeated processes, which may damage the second active material layer 23 due to the high laser heat.

[0079] For example, the width of the second groove 52 can be in the range of approximately 40 μm to 70 μm, and the depth of the second groove 52 can be in the range of approximately 10 μm to 30 μm. Furthermore, the gap between two adjacent second grooves 52 can be in the range of approximately 1.0 mm to 1.8 mm.

[0080] When the width of the second groove 52 is less than about 40 μm or the depth of the second groove 52 is less than about 10 μm, the effect of increasing the surface area of ​​the second active material layer 23 may be insufficient, and therefore the effect of improving the impregnation of the electrolyte may be low. When the width of the second groove 52 exceeds about 70 μm or the depth of the second groove 52 exceeds about 30 μm, the active material may be significantly or excessively removed by the laser, which may reduce the loading level of the second active material layer 23, and the second active material layer 23 may be damaged by the high-energy laser.

[0081] The negative electrode 20 constructed as described above can be manufactured, for example, by the following process: applying a negative electrode active material slurry to the first and second surfaces of the negative electrode substrate 21, drying and pressing the applied negative electrode active material slurry to form a first active material layer 22 and a second active material layer 23, patterning a plurality of first grooves 51 on the first active material layer 22, patterning a plurality of second grooves 52 on the second active material layer 23, and cutting the negative electrode substrate 21 and the first active material layer 22 and the second active material layer 23.

[0082] For example, multiple first grooves 51 can be created by needle punching, and multiple second grooves 52 can be created by laser processing. Since laser processing can be applied to stationary negative electrodes or negative electrodes transported at low speeds, the processing speed of the negative electrode may be slightly reduced. On the other hand, needle punching can be applied to negative electrodes transported in roll-to-roll equipment, allowing for the maintenance of high processing speeds for the negative electrode.

[0083] When multiple first grooves 51 and multiple second grooves 52 are patterned, by appropriately combining needle punching and laser processing, the surface roughening effect of the negative electrode 20 can be achieved while reducing or minimizing the processing speed of the negative electrode 20.

[0084] The negative electrode 20 can then be laminated together with the positive electrode 10 and the two separators 30, and can be wound around the two rotation axes AX1 and AX2. A plurality of first grooves 51 can be located throughout the entire first active material layer 22, and a plurality of second grooves 52 can be located throughout the entire second active material layer 23. That is, a plurality of first grooves 51 and a plurality of second grooves 52 can be located throughout the entire central portion 41 and a pair of curved portions 42.

[0085] Figure 7 This is an enlarged cross-sectional view of the negative electrode in the electrode assembly according to the second embodiment.

[0086] Reference Figure 7 The electrode assembly of the second example embodiment has the same or similar structure as the first example embodiment described above, except that the plurality of first grooves 51 and the plurality of second grooves 52 are located in the bent portion 42, or are located only in the bent portion 42.

[0087] The negative electrode 20a can be divided into the central portion 41 (see...) Figure 1 The corresponding multiple first regions A10 and a pair of curved portions 42 (see) Figure 1 The corresponding multiple second regions A20. Figure 7 The first region A10 shown is the flat portion of the negative electrode 20a, and the second region A20 is the curved portion of the negative electrode 20a. Figure 7 In the image, two first regions A10 and one second region A20 are magnified and shown.

[0088] Multiple first grooves 51 may be located in the second region A20 of the first active material layer 22, and multiple second grooves 52 may be located in the second region A20 of the second active material layer 23. The negative electrode 20a can increase the impregnation of the electrolyte by the multiple first grooves 51 and multiple second grooves 52 in the multiple second regions A20 corresponding to the bent portion 42, and can effectively reduce or inhibit the formation of precipitates in the bent portion 42.

[0089] Figure 8 This is a perspective view of the electrode assembly according to a third example embodiment.

[0090] Reference Figure 8 The electrode assembly 101 of the third example embodiment has a structure that is substantially the same as or similar to that of the first example embodiment or the second example embodiment described above, except that the positive terminal piece 16 and the negative terminal piece 26 are shaped.

[0091] The positive electrode terminal 16 may be or include a portion of an edge of the positive electrode substrate that is not covered by the positive electrode active material layer. The negative electrode terminal 26 may be or include a portion of an edge of the negative electrode substrate that is not covered by the negative electrode active material layer. The positive electrode terminal 16 and the negative electrode terminal 26 may be positioned on opposite sides of the electrode assembly 101.

[0092] At least a portion of the positive terminal piece 16 can be compressed under pressure and integrally fixed by methods such as welding. At least some portions of the negative terminal piece 26 can be compressed under pressure and integrally fixed by methods such as welding.

[0093] Figure 9 This is a perspective view of the electrode assembly according to the fourth example embodiment. Figure 10 yes Figure 9 A cross-sectional view of the electrode assembly shown. Figure 11 It shows the negative electrode. Figure 9 A partially enlarged sectional view.

[0094] Reference Figures 9 to 11 Except for the laminate being wound around a rotation axis, the electrode assembly 102 of the fourth example embodiment has a construction substantially the same as or similar to that of the first example embodiment described above. During the winding of the laminate, a center pin (not shown) may form the rotation axis. The center pin may be retained in the electrode assembly 102 or may be removed from the electrode assembly 102 after the laminate is wound.

[0095] The positive terminal piece 17 may extend toward one side (e.g., the lower side) of the electrode assembly 102, and the negative terminal piece 27 may extend toward the opposite side (e.g., the upper side) of the electrode assembly 102. Multiple cutting lines may be located on the positive terminal piece 17 and the negative terminal piece 27. The positive terminal piece 17 may be folded inward toward the center of the electrode assembly 102, and the negative terminal piece 27 may also be folded inward toward the center of the electrode assembly 102.

[0096] Multiple first grooves 51 may be formed in the first active material layer 22 of the negative electrode 20b, and multiple second grooves 52 may be formed in the second active material layer 23 of the negative electrode 20b. The multiple first grooves 51 may be located on some or all of the first active material layer 22. The multiple second grooves 52 may be parallel to the width direction of the negative electrode 20b (vertical direction based on the figures) and may be located on some or all of the second active material layer 23.

[0097] The negative electrode 20b can increase the impregnation of the electrolyte through multiple first grooves 51 and multiple second grooves 52, and can effectively reduce or inhibit the formation of precipitates. Furthermore, the second active material layer 23, used in a slightly more demanding manner than the first active material layer 22, can further increase the impregnation of the electrolyte through the line pattern of the second grooves 52. Figure 10 In the diagram, 10b represents the positive electrode.

[0098] Figure 12 This is an exploded perspective view of a rechargeable battery according to an example embodiment.

[0099] Reference Figure 12 The rechargeable battery 300 according to this example embodiment may include an electrode assembly 100 and a pouch-shaped housing 120, the pouch-shaped housing 120 being configured to contain and seal the electrode assembly 100 and the electrolyte within an internal space. The electrode assembly 100 may be the electrode assembly described in the first or second example embodiment above.

[0100] The housing 120 may include one side covering the electrode assembly 100 (based on...) Figure 12 The first housing 121 (on the lower side) and the opposite side of the covering electrode assembly 100 (based on) Figure 12 The first housing 121 and the second housing 122 may be connected (e.g., integrally connected), and a fold line 123 may be located between the first housing 121 and the second housing 122. A recess 124 configured to accommodate the electrode assembly 100 may be located in the first housing 121.

[0101] When the second housing 122 is unfolded (opened) relative to the first housing 121, the electrode assembly 100 can be accommodated in the recessed portion 124, and the second housing 122 can be folded to cover the electrode assembly 100. The three edges of the first housing 121 and the second housing 122, excluding the fold line 123, can be joined to each other by, for example, thermal fusion to form a sealing portion 125.

[0102] The rechargeable battery 300 may include a first strip terminal 130 and a second strip terminal 140 made of or comprising a solid metal rod. The first strip terminal 130 may include an inner portion 131 fixed to the positive terminal piece 15, an intermediate portion 132 overlapping the sealing portion 125 of the housing 120, and an outer portion 133 exposed to the outside of the housing 120. The second strip terminal 140 may include an inner portion 141 fixed to the negative terminal piece 25, an intermediate portion 142 overlapping the sealing portion 125 of the housing 120, and an outer portion 143 exposed to the outside of the housing 120.

[0103] The first strip terminal 130 and the second strip terminal 140 are external terminals that can be connected to an external device (not shown) and can electrically connect the electrode assembly 100 to the external device. Because the sealing portion 125 of the housing 120 has weak adhesion to metal, insulating films 134, 144 can surround the intermediate portions 132, 142 to increase the adhesion strength of the first strip terminal 130 and the second strip terminal 140 to the housing 120. The insulating films 134, 144 can be made of a polymer resin having a melting point lower than that of the sealing portion 125 of the housing 120, or can comprise a polymer resin having a melting point lower than that of the sealing portion 125 of the housing 120.

[0104] The internal temperature and pressure of the rechargeable battery 300 may rise rapidly due to various reasons, such as rapid charging and discharging, external impact, and exposure to high-temperature environments. In this case, the insulating films 134 and 144 can melt before the sealing portion 125 of the housing 120, thereby releasing the gas inside the housing 120. Therefore, the insulating films 134 and 144 can constitute a safety vent to release gas and reduce or prevent rapid damage to the rechargeable battery 300.

[0105] Figure 13 This is a perspective view of a rechargeable battery according to another example embodiment. Figure 14 yes Figure 13 The image shows a cross-sectional view of a rechargeable battery.

[0106] Reference Figure 13 and Figure 14 The rechargeable battery 301 according to this example embodiment may include an electrode assembly 101 and a housing 150, the housing 150 being configured to contain and seal the electrode assembly 101 and the electrolyte within an internal space. The electrode assembly 101 may be the electrode assembly of the third example embodiment described above. The housing 150 may have a generally rectangular shape, and the rechargeable battery 301 of this example embodiment may be, for example, a prismatic rechargeable battery.

[0107] The housing 150 may include a can 151 and a cover 152. The can 151 has a recessed internal space and is open on one side. The cover 152 is attached to the can 151 to seal it. The can 151 may be made of or comprise high-strength metal, such as stainless steel. A positive terminal 160, a negative terminal 170, and a safety vent 185 may be mounted on the cover 152.

[0108] The positive terminal 160 may include a first rivet 161 and a first terminal block 162, and can be electrically connected to the positive electrode via a first current collector 163 and a first connector 164. The first current collector 163 may be bonded to the positive terminal piece 16, for example, by soldering. The negative terminal 170 may include a second rivet 171 and a second terminal block 172, and can be electrically connected to the negative electrode via a second current collector 173 and a second connector 174. The second current collector 173 may be bonded to the negative terminal piece 26, for example, by soldering.

[0109] Each of the positive terminal 160 and the negative terminal 170 is insulated from the cover plate 152 by an upper insulator 181, a sealing gasket 182, and a lower insulator 183. The sealing gasket 182 substantially prevents external moisture from penetrating into the housing 150 and prevents the electrolyte inside the housing 150 from leaking to the outside of the rechargeable battery 301.

[0110] A vent 184 may be located in the cover plate 152, and a safety vent 185 may be installed in the vent 184 of the cover plate 152. The safety vent 185 may be a metal plate with a thickness less than that of the cover plate 152, and may include a notch 186 that ruptures under a predetermined or desired pressure to release internal pressure. A plug 187 may seal the electrolyte injection port provided in the cover plate 152.

[0111] Figure 15 This is a perspective view of a rechargeable battery according to another example embodiment. Figure 16 yes Figure 15 The image shows a cross-sectional view of a rechargeable battery.

[0112] Reference Figure 15 and Figure 16 The rechargeable battery 302 according to this example embodiment may include an electrode assembly 102 and a housing 210, the housing 210 being configured to contain and seal the electrode assembly 102 and the electrolyte within an internal space. The electrode assembly 102 may be the electrode assembly of the fourth example embodiment described above. The housing 210 may be approximately cylindrical, and the rechargeable battery 302 of this embodiment may be a cylindrical rechargeable battery.

[0113] The positive current collector 220 can be located on one side (e.g., the lower side) of the electrode assembly 102, and the negative current collector 230 can be located on the opposite side (e.g., the upper side) of the electrode assembly 102. The positive current collector 220 can be fixed to the positive terminal piece 17, and the negative current collector 230 can be fixed to the negative terminal piece 27.

[0114] The housing 210 may include a can 240 and a cover 250, the can 240 having a recessed interior space and being open on one side, and the cover 250 being attached to the can 240 to seal the can 240. The can 240 may include a bottom portion 241 and a side portion 242 connected to the edge of the bottom portion 241. When the rechargeable battery 302 is inverted, the bottom portion 241 may be referred to as the top portion.

[0115] The rolled edge portion 243 and the crimped portion 244 can be provided on the side portion 242. The rolled edge portion 243 can be deformed concavely toward the interior of the housing 210, and the crimped portion 244 can be the end of the side portion 242 that is bent toward the interior of the housing 210. The electrode assembly 102, the positive current collector 220, and the negative current collector 230 can be accommodated in the space between the bottom portion 241 and the rolled edge portion 243, and the rolled edge portion 243 can reduce or suppress movement inside the can 240.

[0116] The terminal hole can be located at the center of the bottom portion 241, and the terminal portion 260 can be mounted in the terminal hole via an insulator. The terminal portion 260 can be coupled to the positive current collector 220 and can form a positive terminal. The negative current collector 230 can include a plurality of connectors 231. The plurality of connectors 231 can be fixed to the inner surface of the crimped portion 243, and the can 240 can form a negative terminal.

[0117] The cover plate 250 may be located outside the negative current collector 230, and the edge of the cover plate 250 may be secured between the crimped portion 243 and the crimped portion 244 via an insulating washer 271. The cover plate 250 may be non-polar. A notch 251 may be located on one surface of the cover plate 250 and is configured to rupture and release internal pressure under a predetermined or desired pressure.

[0118] Figure 17 This is a graph showing the lifespan characteristics of the example rechargeable battery and the rechargeable batteries of Comparative Example 1 and Comparative Example 2. Figure 17 In the diagram, the horizontal axis represents the number of charge and discharge cycles, and the vertical axis represents the discharge capacity (%).

[0119] The example rechargeable battery includes an electrode assembly of the first example embodiment. The rechargeable battery of Comparative Example 1 includes an electrode assembly in which a plurality of first recesses are disposed in a first active material layer and a second active material layer. The rechargeable battery of Comparative Example 2 includes an electrode assembly in which a plurality of second recesses are disposed in a first active material layer and a second active material layer.

[0120] In the examples and comparative examples 1 and 2, a plurality of first grooves are arranged with the same shape, the same size, and the same spacing, and a plurality of second grooves are arranged with the same shape, the same size, and the same spacing. Except for the pattern shape of the negative electrode, the rechargeable batteries in the examples and comparative examples 1 and 2 have the same construction, for example, one of the constructions described above.

[0121] Reference Figure 17 Compared to Example 1, the rechargeable battery exhibits a desired or improved initial discharge capacity, but its discharge capacity decreases rapidly with increasing cycle count, resulting in the lowest long-term lifetime characteristics. Comparative Example 2's rechargeable battery also exhibits desired or improved long-term lifetime characteristics, but displays the lowest discharge capacity during initial operation up to 150 cycles. On the other hand, the example rechargeable batteries maintain a high initial discharge capacity while exhibiting desired or improved long-term lifetime characteristics.

[0122] While this disclosure has been described in conjunction with what are now considered to be exemplary embodiments, it will be understood that the disclosure is not limited to the disclosed exemplary embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. An electrode assembly, the electrode assembly comprising: Diaphragm; as well as Positive and negative electrodes are positioned such that the diaphragm is wound together between the positive and negative electrodes. The negative electrode includes a negative electrode substrate, a first active material layer located on a first surface of the negative electrode substrate, and a second active material layer located on a second surface of the negative electrode substrate. Multiple first grooves are formed in the first active material layer, and Multiple second grooves are formed in the second active material layer, and the multiple second grooves have different patterns from the multiple first grooves.

2. The electrode assembly according to claim 1, wherein: The first surface faces the interior of the electrode assembly, and The plurality of first grooves are positioned in a dot pattern.

3. The electrode assembly according to claim 2, wherein: The plurality of first grooves are positioned in a dot pattern, and One or more of the plurality of first grooves have a width that decreases as their distance from the negative electrode substrate decreases.

4. The electrode assembly according to claim 2, wherein: The width of one or more of the plurality of first grooves is in the range of 20 μm to 60 μm. One or more of the plurality of first grooves have a depth in the range of 30 μm to 70 μm, and The density of the plurality of first grooves is 100 EA / mm². 2 Up to 450EA / mm 2 Within the range.

5. The electrode assembly according to claim 1, wherein: The second surface faces the outside of the electrode assembly, and The plurality of second grooves are positioned in a line pattern.

6. The electrode assembly according to claim 5, wherein, The plurality of second grooves are positioned parallel to the width direction of the negative electrode and are positioned at a certain distance from each other in the length direction of the negative electrode.

7. The electrode assembly according to claim 5, wherein: One or more of the plurality of second grooves have a width greater than their depth, and One or more of the plurality of second grooves have a constant width in the thickness direction of the negative electrode.

8. The electrode assembly according to claim 5, wherein: One or more of the plurality of second grooves have a width in the range of 40 μm to 70 μm, and The depth of one or more of the plurality of second grooves is in the range of 10 μm to 30 μm.

9. An electrode assembly, the electrode assembly comprising: Diaphragm; as well as Positive and negative electrodes are positioned such that the diaphragm is wound together between the positive and negative electrodes. The negative electrode includes a negative electrode substrate, a first active material layer located on the inner surface of the negative electrode substrate, and a second active material layer located on the outer surface of the negative electrode substrate. Multiple first grooves are formed in the first active material layer. Multiple second grooves are formed in the second active material layer, and the multiple second grooves have different patterns from the multiple first grooves. The area of ​​the surface region exposed by the plurality of second grooves in the second active material layer is greater than the area of ​​the surface region exposed by the plurality of first grooves in the first active material layer.

10. The electrode assembly according to claim 9, wherein: The plurality of first grooves are positioned in a dot pattern, and The plurality of second grooves are positioned in a line pattern.

11. The electrode assembly of claim 10, wherein: The plurality of first grooves are positioned in a dot pattern, and One or more of the plurality of first grooves have a width that decreases as their distance from the negative electrode substrate decreases.

12. The electrode assembly according to claim 11, wherein: The width of one or more of the plurality of first grooves is in the range of 20 μm to 60 μm. One or more of the plurality of first grooves have a depth in the range of 30 μm to 70 μm, and The density of the plurality of first grooves is 100 EA / mm². 2 Up to 450EA / mm 2 Within the range.

13. The electrode assembly according to claim 10, wherein, The plurality of second grooves are positioned in a line pattern parallel to the width direction of the negative electrode and are spaced apart from each other in the length direction of the negative electrode.

14. The electrode assembly of claim 13, wherein: One or more of the plurality of second grooves have a width greater than their depth, and One or more of the plurality of second grooves have a constant width in the thickness direction of the negative electrode.

15. The electrode assembly of claim 14, wherein: One or more of the plurality of second grooves have a width in the range of 40 μm to 70 μm, and The depth of one or more of the plurality of second grooves is in the range of 10 μm to 30 μm.

16. The electrode assembly according to claim 1, wherein: The negative electrode includes a flat portion and a curved portion, and The plurality of first grooves and the plurality of second grooves are positioned at least in the curved portion.

17. The electrode assembly of claim 16, wherein, The plurality of first grooves and the plurality of second grooves are positioned throughout the flat portion and the curved portion.

18. A rechargeable battery, said rechargeable battery comprising: The electrode assembly according to claim 1 or 9; as well as The housing is configured to contain and seal the electrode assembly and electrolyte within an internal space.

19. The rechargeable battery according to claim 18, wherein: The electrode assembly is wound around two axes of rotation and includes a central portion and a pair of curved portions located on either side of the central portion. The plurality of first grooves and the plurality of second grooves are located at least in the pair of curved portions.

20. The rechargeable battery according to claim 18, wherein: The electrode assembly is wound around a rotation axis. The plurality of first grooves are located throughout the entire first active material layer, and The plurality of second grooves are located throughout the second active material layer.

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