Electrode assembly and rechargeable battery having the same

Abstract

Provided are an electrode assembly and a rechargeable battery having the same, the electrode assembly including a separator, and a positive electrode and a negative electrode, with the separator interposed between the positive electrode and the negative electrode, the positive electrode and the negative electrode being wound together with the separator. The negative electrode may include: a negative electrode substrate; a first active material layer disposed on one surface of the negative electrode substrate; and a second active material layer disposed on the other surface of the negative electrode substrate. The first active material layer may include a carbon-based active material, a silicon-based active material, and carbon nanotubes. The second active material layer may include a carbon-based active material.

Description

Technical Field

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

[0002] Rechargeable batteries can be 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 in vehicles such as electric vehicles and hybrid vehicles. Rechargeable batteries may include wound electrode assemblies. Wound electrode assemblies may include a positive electrode and a negative electrode, and a separator disposed therebetween, with the positive and negative electrodes wound together with the separator.

[0003] In lithium rechargeable batteries, the negative electrode active material layer can include carbon-based and / or silicon-based active materials. The negative electrode active material layer undergoes volume changes, expanding during charging and contracting during discharging. While effectively increasing the capacity of the negative electrode, silicon-based active materials experience greater volume changes than carbon-based active materials during charging or discharging, which can lead to cracking and thus reduce reversible capacity. Summary of the Invention

[0004] Examples of this disclosure include electrode assemblies in which cracking and the resulting capacity reduction are prevented or inhibited by reducing or suppressing volume changes in the silicon-based active material while increasing the capacity of the negative electrode. The disclosed examples also include rechargeable batteries having this electrode assembly.

[0005] According to an example embodiment, the electrode assembly includes a separator, a positive electrode, and a negative electrode, with the separator disposed between the positive and negative electrodes. The positive and negative electrodes are wound together with the separator. The negative electrode includes: a negative electrode substrate; a first active material layer disposed on one surface of the negative electrode substrate; and a second active material layer disposed on the other surface of the negative electrode substrate. The content of silicon-based active material in the first active material layer differs from the content of silicon-based active material in the second active material layer.

[0006] The first active material layer may include carbon-based and silicon-based active materials, and the second active material layer may also include carbon-based active materials. The second active material layer may further include silicon-based active materials, and the content of silicon-based active materials in the first active material layer may be greater than the content of silicon-based active materials in the second active material layer.

[0007] The first active material layer may further include, for example, carbon nanotubes as a conductive material. The second active material layer may further include, for example, carbon nanotubes as a conductive material, and the content of carbon nanotubes in the first active material layer may be greater than the content of carbon nanotubes in the second active material layer.

[0008] According to another example embodiment, the electrode assembly includes a separator and positive and negative electrodes, with the separator disposed between the positive and negative electrodes, and the positive and negative electrodes wound together with the separator. The negative electrode includes: a negative electrode substrate; a first active material layer disposed on one surface of the negative electrode substrate; and a second active material layer disposed on the other surface of the negative electrode substrate. The first active material layer includes a carbon-based active material, a silicon-based active material, and, for example, carbon nanotubes as a conductive material, and the second active material layer includes a carbon-based active material.

[0009] The second active material layer may further include silicon-based active materials, and the content of silicon-based active materials in the first active material layer may be greater than the content of silicon-based active materials in the second active material layer. The second active material layer may also include, for example, carbon nanotubes as conductive materials, and the content of carbon nanotubes in the first active material layer may be greater than the content of carbon nanotubes in the second active material layer.

[0010] The active material in the first active material layer may comprise about 80% to about 98% by weight of carbon-based active material and about 2% to about 20% by weight of silicon-based active material, and for every 100 parts by weight of active material, the first active material layer may comprise about 0.01 parts by weight to about 0.1 parts by weight of carbon nanotubes. The active material in the second active material layer may comprise about 98% to about 100% by weight of carbon-based active material and about 2% or less by weight of silicon-based active material. For about 100 parts by weight of active material, the second active material layer may comprise about 0.01 parts by weight or less of carbon nanotubes.

[0011] The first active material layer may be disposed on one inner surface of the negative electrode substrate facing the electrode assembly, and the second active material layer may be disposed on another outer surface of the negative electrode substrate facing the electrode assembly. The positive electrode may include: a positive electrode substrate; a third active material layer disposed on one inner surface of the positive electrode substrate facing the electrode assembly; and a fourth active material layer disposed on another outer surface of the positive electrode substrate facing the electrode assembly.

[0012] The first and second active material layers can have the same loading level, and the loading level of the fourth active material layer can be greater than that of the third active material layer. Optionally, the third and fourth active material layers can have the same loading level, and the loading level of the first active material layer can be less than that of the second active material layer. The loading level represents the weight of active material per unit area.

[0013] Optionally, the first active material layer may be disposed on one outer surface of the negative electrode substrate facing the electrode assembly, and the second active material layer may be disposed on another inner surface of the negative electrode substrate facing the electrode assembly. The positive electrode may include: a positive electrode substrate; a third active material layer disposed on one inner surface of the positive electrode substrate facing the electrode assembly; and a fourth active material layer disposed on another outer surface of the positive electrode substrate facing the electrode assembly.

[0014] The first and second active material layers can have the same loading level, and the loading level of the third active material layer can be greater than that of the fourth active material layer. Optionally, the third and fourth active material layers can have the same loading level, and the loading level of the first active material layer can be less than that of the second active material layer.

[0015] According to an example embodiment, the rechargeable battery includes: an electrode assembly; a cylindrical housing enclosing the electrode assembly within an internal space; and a cover plate coupled to an open end of the housing and sealing the housing. The electrode assembly may have an electrode core shape.

[0016] According to an example embodiment, the rechargeable battery includes: an electrode assembly; and a pouch-shaped housing that encloses and seals the electrode assembly. The electrode assembly may include a flat central portion and a pair of circular portions disposed on either side of the central portion and each having a curvature.

[0017] As described above, while increasing the capacity of the negative electrode due to the high content of silicon-based active material in the first active material layer, the electrode assembly according to the exemplary embodiment can be prevented from experiencing cracking and any resulting capacity reduction by reducing or suppressing the volume change of silicon-based active material in the first active material layer. Attached Figure Description

[0018] Figure 1 This is a perspective view of the electrode assembly according to the first example embodiment.

[0019] Figure 2 It is shown Figure 1 An exploded perspective view of the electrode assembly in its unfolded state, as shown in the figure.

[0020] Figure 3 yes Figure 1 The image shows an enlarged view of a portion of a cross-section of the electrode assembly cut along its longitudinal direction.

[0021] Figure 4 yes Figure 1 An enlarged view of a portion of a cross-section of the electrode assembly shown, cut in a direction substantially perpendicular to its longitudinal direction.

[0022] Figure 5 This is an enlarged view of a portion of a cross-section of the electrode assembly according to the second embodiment, cut in a direction substantially perpendicular to its longitudinal direction.

[0023] Figure 6 This is a perspective view of the electrode assembly according to a third example embodiment.

[0024] Figure 7 This is a perspective view of a rechargeable battery according to a fourth example embodiment.

[0025] Figure 8 yes Figure 7 The image shows a cross-sectional view of a rechargeable battery.

[0026] Figure 9 This is an exploded perspective view of a rechargeable battery according to a fifth exemplary embodiment. Detailed Implementation

[0027] Hereinafter, exemplary embodiments of the present disclosure are described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily practice the present disclosure. The present disclosure may be implemented in various different forms and is not limited to the exemplary embodiments described herein.

[0028] When the terms “approximately” or “substantially” are used in conjunction with numerical values ​​in this specification, it means that the relevant numerical value includes a tolerance of ±10% above or below the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0029] Figure 1 This is a perspective view of the electrode assembly according to the first example embodiment. Figure 2 It is shown Figure 1 An exploded perspective view of the electrode assembly in its unfolded state, as shown in the figure. Figure 3 yes Figure 1 The image shows an enlarged view of a portion of a cross-section of the electrode assembly cut along its longitudinal direction. Figure 4 yes Figure 1 An enlarged view of a portion of a cross-section of the electrode assembly shown, cut in a direction substantially perpendicular to its longitudinal direction.

[0030] Reference Figures 1 to 4 In this example embodiment, the electrode assembly 100 may include a stack comprising a positive electrode 120, a diaphragm 130, and a negative electrode 140, and wound multiple times around a central pin (not shown). Each of the positive electrode 120, the diaphragm 130, and the negative electrode 140 may have an elongated strip shape, and the stack may be wound in the form of an electrode core.

[0031] The laminate can be laminated in the order of, for example, the negative electrode 140, the separator 130, the positive electrode 120, and the separator 130 from the inside facing the center pin. In the example, the positions of the positive electrode 120 and the negative electrode 140 can be exchanged. The center pin can be removed after winding the laminate, and an empty space can be provided at the center of the electrode assembly 100.

[0032] The positive electrode 120 can include a positive electrode substrate 121 and a positive electrode active material layer 122 provided on at least one surface of the positive electrode substrate 121. The positive electrode substrate 121 can be referred to as a positive electrode current collector. The positive electrode substrate 121 can be made of or include aluminum, etc., and can be in the form of a thin plate or foam. The positive electrode active material layer 122 can include a positive electrode active material and selectively further include a binder and / or a conductive material.

[0033] The positive electrode active material can include a lithium transition metal composite oxide. The positive electrode active material can include at least one of, for example, lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, and cobalt-free lithium nickel manganese-based oxides.

[0034] The negative electrode 140 can include a negative electrode substrate 141 and a negative electrode active material layer 142 provided on at least one surface of the negative electrode substrate 141. The negative electrode substrate 141 can be referred to as a negative electrode current collector. The negative electrode substrate 141 can be made of or include copper, nickel, a copper alloy, or a nickel alloy, and can be in the form of a thin plate or foam. The negative electrode active material layer 142 can include a negative electrode active material and can selectively further include a binder and / or a conductive material.

[0035] The negative electrode active material can include at least one of a carbon-based active material and a silicon-based active material. The carbon-based active material can include at least one of natural graphite and artificial graphite. The silicon-based active material can include at least one of a silicon-carbon composite active material and silicon oxide (SiO x , 0 < x ≤ 2).

[0036] In each or at least one of the positive electrode active material layer 122 and the negative electrode active material layer 142, the binder can include at least one of an aqueous binder, a non-aqueous binder, and a dry binder. In each or at least one of the positive electrode active material layer 122 and the negative electrode active material layer 142, the conductive material can include at least one of the following: carbon-based materials, such as one or more of natural graphite, artificial graphite, carbon black, carbon fiber, carbon nanofiber, or carbon nanotube; metal materials, in the form of metal powder or metal fiber including one or more of copper, nickel, aluminum, silver, etc., or including metal powder or metal fiber containing one or more of copper, nickel, aluminum, silver, etc.; or conductive polymers, such as polyphenylene derivatives.

[0037] The separator 130 may be made of or comprise a porous substrate or a porous substrate having at least one coating layer disposed on at least one surface. The porous substrate may include at least one of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester, polycarbonate, and polyimide. The coating layer may include an adhesive, and the adhesive may include a polyvinylidene fluoride (PVDF) compound. The separator 130 may insulate the positive and negative electrodes from each other while allowing lithium ion movement.

[0038] In the positive electrode 120, the positive electrode active material layer 122 may be disposed on the remaining portion of the positive electrode substrate 121 except for one side (e.g., the lower edge). The portion of the positive electrode substrate 121 not covered by the positive electrode active material layer 122 and whose surface is exposed may be referred to as the positive electrode uncoated region 125. In the negative electrode 140, the negative electrode active material layer 142 may be disposed on the remaining portion of the negative electrode substrate 141 except for the other side (e.g., the upper edge). The portion of the negative electrode substrate 141 not covered by the negative electrode active material layer 142 and whose surface is exposed may be referred to as the negative electrode uncoated region 145.

[0039] The positive electrode uncoated region 125 may include a pair of edge uncoated regions 126 and a central uncoated region 127 disposed between the pair of edge uncoated regions 126. The negative electrode uncoated region 145 may include a pair of edge uncoated regions 146 and a central uncoated region 147 disposed between the pair of edge uncoated regions 146. In the width direction of the positive electrode 120 and the negative electrode 140 ( Figure 2 The height of the uncoated edge regions 126 and 146 measured in the W direction can be less than the height of the uncoated center regions 127 and 147.

[0040] The uncoated central regions 127 and 147 may be bent inward toward the winding center of the electrode assembly 100. Multiple cutting lines may be provided in the uncoated central regions 127 and 147 to facilitate bending. The sides of the uncoated central regions 127 and 147 and the multiple cutting lines may be formed along a diagonal direction with respect to the width direction W, and are not limited to this example.

[0041] The uncoated central region 127 of the positive electrode 120 can be fixed to the positive current collector (not shown), and the uncoated central region 147 of the negative electrode 140 can be fixed to the negative current collector (not shown). The inwardly curved and overlapping uncoated central regions 127 and 147 can increase the current collection efficiency of the positive electrode 120 and the negative electrode 140. In various examples, the electrode assembly 100, the positive current collector, and the negative current collector can be stored together with the electrolyte in a housing (not shown).

[0042] Reference Figure 4 Each or at least one of the positive electrode 120, negative electrode 140, and separator 130 may have a predetermined or desired curvature. The negative electrode active material layer 142 may include a first active material layer 143 disposed on one surface of the negative electrode substrate 141 and a second active material layer 144 disposed on the other surface of the negative electrode substrate 141.

[0043] The first active material layer 143 can be disposed on one surface of the negative electrode substrate 141 facing the center (inner side) of the electrode assembly 100, and the second active material layer 144 can be disposed on another surface of the negative electrode substrate 141 facing the electrode assembly 100. Due to the curvature of the negative electrode 140, compressive stress will act on the first active material layer 143, and tensile stress will act on the second active material layer 144.

[0044] The first active material layer 143 and the second active material layer 144 may contain different amounts of silicon-based active material. In the example, the first active material layer 143 and the second active material layer 144 may contain different amounts of carbon nanotubes as conductive materials or included in conductive materials. Carbon nanotubes, as conductive materials, can reduce the resistance of the silicon-based active material in the first active material layer 143 and the second active material layer 144, thereby allowing the silicon-based active material to react smoothly with lithium. The carbon nanotubes may include at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0045] In this example, the content of silicon-based active material included in the first active material layer 143 can be greater than the content of silicon-based active material included in the second active material layer 144. Additionally, the content of carbon nanotubes included in the first active material layer 143 can be greater than the content of carbon nanotubes included in the second active material layer 144.

[0046] The active material in the first active material layer 143 may include, for example, about 80% to about 98% by weight of carbon-based active material and about 2% to about 20% by weight of silicon-based active material. For 100 parts by weight of active material, the first active material layer 143 may include about 0.01 parts by weight to about 0.1 parts by weight of carbon nanotubes as conductive materials.

[0047] The active material in the second active material layer 144 may include, for example, about 98% to about 100% by weight of a carbon-based active material and about 2% or less by weight of a silicon-based active material. For 100 parts by weight of the active material, the second active material layer 144 may include about 0.01 part by weight or less of carbon nanotubes. The content of the silicon-based active material in the second active material layer 144 may be equal to 0 by weight, or may be about 2% or less and greater than 0. The content of the carbon nanotubes in the second active material layer 144 may be equal to 0 by weight, or may be greater than 0 and about 0.01 part by weight or less.

[0048] In each of the first active material layer 143 and the second active material layer 144, the carbon-based active material may include at least one of natural graphite and artificial graphite, for example, artificial graphite. Artificial graphite may have a higher durability than natural graphite. The silicon-based active material may include at least one of a silicon-carbon composite active material and silicon oxide (SiO x , 0 < x ≤ 2).

[0049] The silicon-carbon composite active material may include at least one of a first composite active material, a second composite active material, and a third composite active material. The first composite active material may include a plurality of silicon nanoparticles and an amorphous carbon coating layer provided on the surface of the silicon nanoparticles. The second composite active material may include a core containing a silicon-carbon composite and a polymer coating layer provided on the surface of the core. The third composite active material may include a core containing a silicon-based material and a carbon-based coating layer provided on the surface of the core.

[0050] When the content of the silicon-based active material in the first active material layer 143 is less than about 2% by weight, it may be difficult to increase the capacity of the negative electrode, and when the content of the silicon-based active material is greater than about 20% by weight, it may become difficult to reduce or suppress the volume expansion of the first active material layer 143. When the content of the carbon nanotubes is less than about 0.01 part by weight, the first active material layer 143 is a material with poor conductivity, and when the content of the carbon nanotubes is greater than about 0.1 part by weight, the negative electrode 140 has a reduced capacity due to the relatively reduced content of the active material in the first active material layer 143.

[0051] When the content of the silicon-based active material in the second active material layer 144 is greater than about 2% by weight, the second active material layer 144 receiving tensile stress has a significant volume expansion. When the content of the carbon nanotubes is greater than about 0.01 part by weight, the negative electrode 140 has a reduced capacity due to the relatively reduced content of the active material in the second active material layer 144.

[0052] The first active material layer 143 or the second active material layer 144 may further include a binder. The binder can increase the adhesion strength between the negative electrode substrate 141 and the first active material layer 143 and the second active material layer 144, and also increase the adhesion strength between the carbon-based active material and the silicon-based active material and / or the conductive material. The binder for the first active material layer 143 and the binder for the second active material layer 144 can be of the same or similar type, or different types. An appropriate content can be determined based on the type of binder.

[0053] The binder may include, for example, at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, polyurethane, polyethylene, polypropylene, epoxy resin, (meth)acrylic resin, polyester resin, and nylon, and is not limited to such examples. The binder for the first active material layer 143 may include materials that contribute to increasing the mechanical strength of the first active material layer 143. The binder for the second active material layer 144 may include materials that contribute to increasing the electrical conductivity and ionic conductivity of the second active material layer 144.

[0054] Typically, silicon-based active materials can have a higher capacity per unit mass than carbon-based active materials. Although this effectively increases the capacity of the negative electrode, silicon-based active materials undergo greater volume changes than carbon-based active materials when the electrode assembly is charged or discharged. This can lead to cracking and thus reduce the reversible capacity.

[0055] In this exemplary embodiment, the first active material layer 143 may include a silicon-based active material having a higher content than that of the second active material layer 144, which can help increase the capacity of the negative electrode 140. Furthermore, the compressive stress acting on the first active material layer 143 can reduce or suppress volume changes in the silicon-based active material within the first active material layer 143. Therefore, while increasing the capacity of the negative electrode 140 due to the higher content of silicon-based active material in the first active material layer 143, reducing or suppressing volume changes in the silicon-based active material in the first active material layer 143 by means of the compressive stress applied to the first active material layer 143 can prevent or inhibit the electrode assembly 100 in this exemplary embodiment from undergoing cracking or capacity reduction.

[0056] The negative electrode 140 constructed as described above can be easily manufactured. For example, the negative electrode 140 can be manufactured by the following process: producing a first slurry for the first active material layer 143 and a second slurry for the second active material layer 144, respectively; applying the first slurry to one surface of the negative electrode substrate 141 and applying the second slurry to the other surface of the negative electrode substrate 141; and drying and pressing the applied first and second slurries.

[0057] As a construction intended to achieve the same objective as the negative electrode 140 constructed as described above, it is assumed that at least one of the first and second active material layers comprises two or more layers with different silicon contents. In this case, multiple coating nozzles must be used to coat the two or more layers separately, which may increase the technical difficulty and complicate the negative electrode manufacturing process. In contrast, the negative electrode 140 constructed as described above can be easily manufactured and is advantageous for mass production.

[0058] Figure 5 This is an enlarged view of a portion of a cross-section of an electrode assembly according to the second example embodiment, cut in a direction substantially perpendicular to its longitudinal direction.

[0059] Reference Figure 5 In the electrode assembly 100A of this exemplary embodiment, a first active material layer 143 may be disposed on one surface of the negative electrode substrate 141 facing the outer side of the electrode assembly 100A, and a second active material layer 144 may be disposed on another surface of the negative electrode substrate 141 facing the center (inner side) of the electrode assembly 100A. Each or at least one of the first active material layer 143 and the second active material layer 144 may be the same as each or at least one of the first active material layer 143 and the second active material layer 144 described in the first exemplary embodiment, and therefore their description is omitted.

[0060] Due to the curvature of the negative electrode 140, compressive stress acts on the second active material layer 144, and tensile stress acts on the first active material layer 143. Compared to the case without curvature, the first active material layer 143 can have a lower volume density due to the curvature and tensile stress. The lower density of the first active material layer 143 can be configured to absorb the volume expansion of the first active material layer 143 when the electrode assembly is charged or discharged, thus reducing or suppressing the volume change of the first active material layer 143. In addition, the lower density of the first active material layer 143 can increase the output of the rechargeable battery by promoting lithium movement through the electrolyte.

[0061] In the first and second example embodiments described above, the first active material layer 143 and the second active material layer 144 may have different capacities per unit mass due to differences in their components. For example, the capacities per unit mass of the first active material layer 143 may be greater than those of the second active material layer 144. The loading level of the first active material layer 143 may be equal to or less than the loading level of the second active material layer 144.

[0062] The positive electrode active material layer 122 may include a third active material layer 123 disposed on one surface of the positive electrode substrate 121 facing the center (inner side) of the electrode assembly 100, 100A, and a fourth active material layer 124 disposed on another surface of the positive electrode substrate 121 facing the electrode assembly 100, 100A.

[0063] Reference Figure 4 In the electrode assembly 100 according to the first example embodiment, the first active material layer 143 may face the fourth active material layer 124, with the separator 130 disposed between them, and the second active material layer 144 may face the third active material layer 123, with the separator 130 disposed between them. (Refer to...) Figure 5 In the electrode assembly 100A according to the second example embodiment, the first active material layer 143 faces the third active material layer 123 with the diaphragm 130 placed between them, and the second active material layer 144 may face the fourth active material layer 124 with the diaphragm 130 placed between them.

[0064] Reference Figure 4 The first active material layer 143 and the second active material layer 144 can have the same or similar loading levels. In this case, the capacity per unit area of ​​the first active material layer 143 can be greater than the capacity per unit area of ​​the second active material layer 144. The loading level of the fourth active material layer 124 facing the first active material layer 143 can be greater than the loading level of the third active material layer 123 facing the second active material layer 144. In this case, the capacity per unit area of ​​the fourth active material layer 124 can be greater than the capacity per unit area of ​​the third active material layer 123.

[0065] On the other hand, the loading level of the first active material layer 143 can be lower than the loading level of the second active material layer 144. In this case, the capacity per unit area of ​​the first active material layer 143 can be similar to that of the second active material layer 144. The loading level of the fourth active material layer 124 can be the same as the loading level of the third active material layer 123. In this case, the capacity per unit area of ​​the fourth active material layer 124 can be the same as that of the third active material layer 123.

[0066] In both of the above cases, by matching the N / P ratio of the first active material layer 143 to the fourth active material layer 124 and the N / P ratio of the second active material layer 144 to the third active material layer 123 to be the same, the capacity ratio (N / P ratio) between the anode and cathode of the positive electrode 120 and the negative electrode 140 can be balanced. The N / P ratio is the capacity per unit area of ​​the negative electrode 140 divided by the capacity per unit area of ​​the positive electrode 120, and can have a value greater than 1.

[0067] Reference Figure 5 The first active material layer 143 and the second active material layer 144 can have the same or similar loading levels. In this case, the capacity per unit area of ​​the first active material layer 143 can be greater than the capacity per unit area of ​​the second active material layer 144. The loading level of the third active material layer 123 facing the first active material layer 143 can be greater than the loading level of the fourth active material layer 124 facing the second active material layer 144. In this case, the capacity per unit area of ​​the third active material layer 123 can be greater than the capacity per unit area of ​​the fourth active material layer 124.

[0068] On the other hand, the loading level of the first active material layer 143 can be lower than the loading level of the second active material layer 144. In this case, the capacity per unit area of ​​the first active material layer 143 can be similar to that of the second active material layer 144. The loading level of the third active material layer 123 can be the same as the loading level of the fourth active material layer 124. In this case, the capacity per unit area of ​​the third active material layer 123 can be the same as that of the fourth active material layer 124.

[0069] In both of the above cases, by matching the N / P ratio of the first active material layer 143 to the third active material layer 123 and the N / P ratio of the second active material layer 144 to the fourth active material layer 124 to be the same, the N / P ratio of the positive electrode 120 and the negative electrode 140 can be balanced.

[0070] Figure 6 This is a perspective view of the electrode assembly according to a third example embodiment.

[0071] Reference Figure 6 The electrode assembly 100B in this example embodiment may include a laminate comprising a positive electrode, a diaphragm, and a negative electrode, wound around two winding shafts AX1 and AX2, and subsequently pressed into a flat shape. In this example, the electrode assembly 100B may include a flat square central portion 150 and a pair of circular portions 160 disposed on either side of the central portion 150. The central portion 150 may be a flat portion having a certain or desired thickness and disposed between the first winding shaft AX1 and the second winding shaft AX2. The pair of circular portions 160 may be semi-circular curved portions respectively surrounding the two winding shafts AX1 and AX2.

[0072] The positive electrode may include at least one positive terminal 170, and the negative electrode may include at least one negative terminal 180. The positive terminal 170 and the negative terminal 180 may extend toward one side (e.g., the upper side) of the electrode assembly 100B. In another example, the positive terminal 170 may extend toward one side of the electrode assembly while the negative terminal 180 extends toward the opposite side of the electrode assembly. Figure 6 An example is shown where the positive terminal 170 and the negative terminal 180 extend toward the same side.

[0073] The electrode assembly 100B in this example embodiment has the same or similar construction as either the first example embodiment or the second example embodiment described above, except that the electrode assembly 100B is wound in a flat manner.

[0074] Figure 7 This is a perspective view of a rechargeable battery according to a fourth example embodiment. Figure 8 yes Figure 7 The image shows a cross-sectional view of a rechargeable battery.

[0075] Reference Figure 7 and Figure 8 The rechargeable battery 200 according to this example embodiment may be a cylindrical rechargeable battery. The rechargeable battery 200 may include a cylindrical housing 210, an electrode assembly 100 or 100A enclosed inside the housing 210, a terminal portion 220 disposed on one side (e.g., the lower side) of the housing 210, and a cover plate 230 disposed on the other side (e.g., the upper side) of the housing 210.

[0076] Electrode assembly 100 or 100A can be any of the electrode assemblies in the first and second example embodiments described above. Positive current collector 240 can be disposed on one side (e.g., the lower side) of electrode assembly 100 or 100A, and negative current collector 250 can be disposed on the other side (e.g., the upper side) of electrode assembly 100 or 100A. Positive current collector 240 can be fixed to the central uncoated area 127 of positive electrode 120 by, for example, welding or another method. Negative current collector 250 can be fixed to the central uncoated area 147 of negative electrode 140 by, for example, welding or another method.

[0077] The housing 210 may include a disc-shaped bottom portion 211 and cylindrical side portions 212 extending upward from the edge of the bottom portion 211. The housing 210 may be made of, for example, at least one of steel, aluminum, and aluminum alloys, or may include, for example, at least one of steel, aluminum, and aluminum alloys. When the top and bottom of the rechargeable battery 200 are interchanged, the bottom portion 211 may be referred to as the top portion. The electrode assembly 100 or 100A, as well as the positive current collector 240 and the negative current collector 250, may be enclosed together with the electrolyte within the internal space of the housing 210.

[0078] A terminal hole may be located at the center of the bottom portion 211, and the terminal portion 220 may be mounted in the terminal hole. The terminal portion 220 may include a first terminal 221 having a disc shape and a second terminal 222 having a generally cylindrical shape. The first terminal 221 may be located on the outer side (e.g., the lower side) of the bottom portion 211, and the second terminal 222 may be inserted into the terminal hole. The second terminal 222 may be riveted to the first terminal 221 and the bottom portion 211.

[0079] The second terminal 222 can be connected to the positive current collector 240, and the terminal portion 220 can be charged with the same polarity as the positive electrode 120, thereby forming a positive terminal. The first insulator 261, the second insulator 262, and the third insulator 263 can be disposed between the housing 210 and the terminal portion 220 to insulate the housing 210 and the terminal portion 220 from each other.

[0080] The rolled edge portion 213 and the crimped portion 214 can be provided on the side portion 212 of the housing 210. The rolled edge portion 213 can be a portion that is deformed inward toward the inside of the housing 210, and the crimped portion 214 can be a portion whose upper end of the side portion 212 is bent toward the inside of the housing 210. The electrode assembly 100 or 100A can be enclosed in the space between the bottom portion 211 and the rolled edge portion 213, and the movement of the electrode assembly 100 or 100A inside the housing 210 can be reduced or suppressed by the rolled edge portion 213.

[0081] The negative electrode current collector 250 may include a body 251 and a plurality of connectors 252 extending upward from the edge of the body 251. The plurality of connectors 252 may contact the rolled edge portion 213 and be fixed to the rolled edge portion 213 by means such as welding. The housing 210 may be charged with the same polarity as the negative electrode 140 by the negative electrode current collector 250, thereby constituting the negative terminal.

[0082] As another example, although not shown, the negative current collector can be attached to the terminal portion, and the positive current collector can include a connector and be secured to the crimped portion. In this case, the housing can constitute the positive terminal, and the terminal portion can constitute the negative terminal.

[0083] A cover plate 230 can be disposed on the outer (upper) side of the negative electrode current collector 250, and the edge of the cover plate 230 can be fixed between the rolled edge portion 213 and the crimped portion 214 via an insulating washer 270. The cover plate 230 and the insulating washer 270 can seal the housing 210, and the cover plate 230 can be non-polar. A notch 235 can be disposed in at least one surface of the cover plate 230. The notch 235 can have a V-shaped profile, and, for example, when viewing the target object from below, the notch 235 can be arc-shaped at its bottom.

[0084] The internal temperature of the rechargeable battery 200 may rise due to various reasons (such as rapid charging and discharging, external impact, and exposure to high-temperature environments), and the internal pressure of the rechargeable battery 200 may increase due to, for example, the evaporation of the electrolyte. When the internal pressure of the rechargeable battery 200 increases, the cover plate 230 may rupture through the notch 235 to release the internal gas.

[0085] Figure 9 This is an exploded perspective view of a rechargeable battery according to a fifth exemplary embodiment.

[0086] Reference Figure 9 In this example embodiment, the rechargeable battery 200A may be a pouch-type rechargeable battery. The rechargeable battery 200A may include an electrode assembly 100B and a housing 280 configured to house and seal the electrode assembly 100B therein. The housing 280 may be referred to as a pouch, and the electrode assembly 100B may be or include the electrode assembly described in the third example embodiment above.

[0087] The housing 280 may include an upper housing 281 and a lower housing 282. The lower housing 282 may include a storage portion 283 as a concave space for receiving the electrode assembly 100B therein and a sealing portion 284 surrounding the storage portion 283. The electrode assembly 100B may be enclosed in the storage portion 283, and the upper housing 281 may be folded to overlap with the lower housing 282 and the electrode assembly 100B enclosed therein. The edge of the upper housing 281 may be joined to the sealing portion 284 by a joining method such as heat fusion.

[0088] Each or one of the upper housing 281 and the lower housing 282 may have a multi-layered structure of metal sheets and polymer sheets. The metal sheets may be or include aluminum sheets and may provide mechanical strength to the housing 280. The polymer sheets may include at least one of, for example, polyethylene terephthalate (PET) sheets, nylon sheets, PET-nylon composite sheets, etc., and provide insulation and protection to the housing 280. The metal sheets may be disposed between at least two polymer sheets.

[0089] A portion of the positive terminal piece 170 and a portion of the negative terminal piece 180 may overlap with the sealing portion 284, and the ends of the positive terminal piece 170 and the negative terminal piece 180 may protrude outside the sealing portion 284. A protective strip (not shown) may be provided on the portions of the positive terminal piece 170 and the negative terminal piece 180 that overlap with the sealing portion 284.

[0090] Although exemplary embodiments of this disclosure have been described above, the scope of this disclosure is not limited thereto. Various modifications can be made within the scope of the patent claims, detailed descriptions, and drawings of this disclosure, and these modifications also fall within the spirit and scope of this disclosure.

Claims

1. An electrode assembly, the electrode assembly comprising: Diaphragm; as well as The device comprises a positive electrode and a negative electrode, with the diaphragm positioned between the positive and negative electrodes, and the positive and negative electrodes being wound together with the diaphragm. The negative electrode comprises: a negative electrode substrate; a first active material layer on one surface of the negative electrode substrate; and a second active material layer on the other surface of the negative electrode substrate. The content of silicon-based active materials in the first active material layer is different from the content of silicon-based active materials in the second active material layer.

2. The electrode assembly according to claim 1, wherein: The first active material layer includes carbon-based active materials and silicon-based active materials, and The second active material layer includes carbon-based active materials.

3. The electrode assembly according to claim 2, wherein: The second active material layer also includes silicon-based active materials, and The content of silicon-based active materials in the first active material layer is greater than the content of silicon-based active materials in the second active material layer.

4. The electrode assembly according to claim 3, wherein, The first active material layer also includes carbon nanotubes.

5. The electrode assembly according to claim 4, wherein: The second active material layer also includes carbon nanotubes, and The carbon nanotube content in the first active material layer is greater than the carbon nanotube content in the second active material layer.

6. An electrode assembly, the electrode assembly comprising: Diaphragm; as well as The device comprises a positive electrode and a negative electrode, with the diaphragm positioned between the positive and negative electrodes, and the positive and negative electrodes being wound together with the diaphragm. The negative electrode comprises: a negative electrode substrate; a first active material layer on one surface of the negative electrode substrate; and a second active material layer on the other surface of the negative electrode substrate. The first active material layer includes carbon-based active materials, silicon-based active materials, and carbon nanotubes, and The second active material layer includes carbon-based active materials.

7. The electrode assembly according to claim 6, wherein: The second active material layer also includes silicon-based active materials, and The content of silicon-based active materials in the first active material layer is greater than the content of silicon-based active materials in the second active material layer.

8. The electrode assembly according to claim 7, wherein: The second active material layer also includes carbon nanotubes, and The carbon nanotube content in the first active material layer is greater than the carbon nanotube content in the second active material layer.

9. The electrode assembly according to claim 7, wherein: The active material in the first active material layer comprises 80% to 98% carbon-based active material and 2% to 20% silicon-based active material by weight. For 100 parts by weight of active material, the first active material layer comprises 0.01 parts by weight to 0.1 parts by weight of carbon nanotubes. The active material in the second active material layer comprises 98% to 100% carbon-based active material and 2% or less silicon-based active material by weight.

10. The electrode assembly according to claim 9, wherein: The second active material layer also includes carbon nanotubes, and For 100 parts by weight of active material, the second active material layer comprises 0.01 parts by weight or less of carbon nanotubes.

11. The electrode assembly according to claim 6, wherein, The first active material layer is on one surface of the negative electrode substrate facing the inner side of the electrode assembly, and the second active material layer is on the other surface of the negative electrode substrate facing the outer side of the electrode assembly.

12. The electrode assembly according to claim 11, wherein, The positive electrode includes: a positive electrode substrate; a third active material layer on one surface of the positive electrode substrate facing the inner side of the electrode assembly; and a fourth active material layer on another surface of the positive electrode substrate facing the outer side of the electrode assembly.

13. The electrode assembly according to claim 12, wherein: The first active material layer and the second active material layer have the same loading level, and The loading level of the fourth active material layer is greater than that of the third active material layer.

14. The electrode assembly according to claim 12, wherein: The third active material layer and the fourth active material layer have the same loading level, and The loading level of the first active material layer is lower than that of the second active material layer.

15. The electrode assembly according to claim 6, wherein, The first active material layer is on one surface of the negative electrode substrate facing the outer side of the electrode assembly, and the second active material layer is on another surface of the negative electrode substrate facing the inner side of the electrode assembly.

16. The electrode assembly of claim 15, wherein, The positive electrode includes: a positive electrode substrate; a third active material layer on one surface of the positive electrode substrate facing the inner side of the electrode assembly; and a fourth active material layer on another surface of the positive electrode substrate facing the outer side of the electrode assembly.

17. The electrode assembly of claim 16, wherein: The first active material layer and the second active material layer have the same loading level, and The loading level of the third active material layer is greater than that of the fourth active material layer.

18. The electrode assembly of claim 16, wherein: The third active material layer and the fourth active material layer have the same loading level, and The loading level of the first active material layer is lower than that of the second active material layer.

19. A rechargeable battery, said rechargeable battery comprising: The electrode assembly according to claim 1; A cylindrical housing encloses the electrode assembly within the internal space of the housing; as well as A cover plate is attached to the open end of the housing and seals the housing. The electrode assembly has a core shape.

20. A rechargeable battery, said rechargeable battery comprising: The electrode assembly according to claim 1; as well as The bag-shaped housing encloses and seals the electrode assembly. The electrode assembly includes a flat central portion and a pair of circular portions on either side of the central portion, each circular portion having a curvature.

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