Electrode assembly and rechargeable battery having the same

Abstract

An electrode assembly and a rechargeable battery having the same are provided. The electrode assembly includes a separator, a first electrode, and a second electrode stacked and wound with the separator between the first electrode and the second electrode. The first electrode includes a first substrate and a first composite layer disposed on the first substrate. The first composite layer is divided into at least two regions along the length direction of the first substrate. At least two regions of the first composite layer have different active material compositions.

Description

Technical Field

[0001] The present disclosure relates to a rechargeable battery, and more particularly, to a rechargeable battery having a wound electrode assembly. Background Art

[0002] Rechargeable batteries are used for a variety of purposes, including as power sources for small electronic devices such as mobile phones and laptop computers, and as power sources for driving motors in transportation vehicles such as electric vehicles and hybrid vehicles. Rechargeable batteries may include a wound electrode assembly. The wound electrode assembly includes a positive electrode and a negative electrode wound together, with a separator positioned between the positive and negative electrodes.

[0003] Typically, the negative electrode undergoes volume changes, increasing during charge and decreasing during discharge. As charge and discharge progress, the wound electrode assembly exhibits relatively large volume changes primarily in the inner wound portion, and reaction degradation can occur primarily in this inner wound portion. Recently, increases in silicon (Si) content in negative electrode active materials to achieve high capacity have led to large volume changes in the negative electrode, which can cause deformation of the electrode assembly and cracking of the substrate. Summary of the Invention

[0004] The present disclosure relates to various embodiments of an electrode assembly configured to reduce deformation of an inner winding portion and occurrence of cracks in a substrate, and a rechargeable battery having the same.

[0005] An electrode assembly according to an embodiment includes a separator, a first electrode, and a second electrode. The first and second electrodes are stacked and wound with the separator positioned therebetween. The first electrode includes a first substrate and a first composite layer disposed on the first substrate. The first composite layer is divided into at least two regions along the length of the first substrate. The at least two regions of the first composite layer have different active material compositions.

[0006] The first substrate may include an inner end and an outer end. The silicon content of the active material in at least two regions may decrease toward the inner end. The at least two regions may include artificial graphite and natural graphite. The content of artificial graphite may increase and the content of natural graphite may decrease toward the inner end.

[0007] The at least two regions may include a first region near the inner end and a second region near the outer end. The active material in the second region may contain less than about 10 wt % silicon. The active material in the first region may not contain silicon or may contain a lower silicon content than the silicon content in the second region. The active material in the first region may include artificial graphite, and the active material in the second region may include natural graphite.

[0008] The electrode assembly may further include an intermediate uncoated region between the first region and the second region. The first electrode may further include a first lead tab attached to the intermediate uncoated region. The first composite layer may include a first imaginary dividing line, a second imaginary dividing line, and a third imaginary dividing line that divide the first composite layer into four equal parts along the length direction of the first substrate, and the intermediate uncoated region may be between the first imaginary dividing line and the third imaginary dividing line.

[0009] The first region and the second region may contact each other. The length of the first region may be smaller than the length of the second region, and the length of the first region may correspond to at least three turns from the inner end. The length of the second region may be smaller than the length of the first region, and the length of the second region may correspond to at least three turns from the outer end.

[0010] An electrode assembly according to another embodiment includes a separator, a first electrode, and a second electrode. The first electrode and the second electrode are stacked and wound with the separator located therebetween. The first electrode includes a first substrate and a first composite layer, and the second electrode includes a second substrate and a second composite layer. The first composite layer is divided into at least two regions along the length direction of the first substrate, and the second composite layer is divided into at least two regions along the length direction of the second substrate. At least two regions of the first composite layer have different active material compositions, and at least two regions of the second composite layer have different loading levels.

[0011] Each of the first substrate and the second substrate may include an inner end and an outer end. The silicon content of the active material in at least two regions of the first composite layer may decrease toward the inner end. The loading level of at least two regions of the second composite layer may decrease toward the inner end. At least two regions of the first composite layer may include artificial graphite and natural graphite. The content of artificial graphite may increase and the content of natural graphite may decrease toward the inner end.

[0012] The at least two regions of the first composite layer may include a first region near the inner end and a second region near the outer end. The active material of the second region may include natural graphite and less than about 10 wt % silicon. The active material of the first region may include artificial graphite and may not include silicon, or may have a silicon content lower than that of the second region.

[0013] The first electrode may further include an intermediate uncoated region between the first region and the second region, and a first lead tab attached to the intermediate uncoated region of the first electrode. The at least two regions of the second composite layer may include a third region corresponding to the first region and a fourth region corresponding to the second region. The second electrode may further include an intermediate uncoated region between the third region and the fourth region, and a second lead tab attached to the intermediate uncoated region of the second electrode.

[0014] The first composite layer may include a first imaginary dividing line, a second imaginary dividing line, and a third imaginary dividing line that divides the first composite layer into four equal parts along the length direction of the first substrate, and the middle uncoated area of ​​the first electrode and the middle uncoated area of ​​the second electrode may be between the first imaginary dividing line and the third imaginary dividing line.

[0015] A rechargeable battery according to an embodiment includes: an electrode assembly; a can that accommodates the electrode assembly and an electrolyte in an inner space of the can; and a cap assembly that is coupled to the can and seals the can. The electrode assembly includes a first electrode and a second electrode that are stacked and wound, and a separator located between the first electrode and the second electrode, and the electrode assembly includes an inner wound portion and an outer wound portion surrounding the inner wound portion. The first electrode includes a first substrate and a first composite layer, and the second electrode includes a second substrate and a second composite layer. The silicon content of the first composite layer in the inner wound portion is lower than that in the outer wound portion. The load level of the second composite layer in the inner wound portion is lower than that in the outer wound portion.

[0016] The first composite layer in the inner wound portion may include artificial graphite, and the first composite layer in the outer wound portion may include natural graphite. The rechargeable battery may further include: a middle uncoated region between the inner and outer wound portions; and first and second lead tabs attached to the middle uncoated region. A first imaginary dividing line, a second imaginary dividing line, and a third imaginary dividing line may divide the first composite layer into four equal parts along the length of the first substrate, and the middle uncoated region may be between the first and third imaginary dividing lines.

[0017] The width of the inner winding portion may be smaller than the width of the outer winding portion, and the inner winding portion may have a length corresponding to at least three turns. A middle uncoated region may be located at the outer winding portion, and the first and second lead tabs may be attached to the middle uncoated region. The width of the outer winding portion may be smaller than the width of the inner winding portion, and the outer winding portion may have a length corresponding to at least three turns. The middle uncoated region may be located at the inner winding portion, and the first and second lead tabs may be attached to the middle uncoated region.

[0018] According to the embodiments, the volume change of the inner wound portion of the electrode assembly can be reduced. As a result, deformation of the inner wound portion and cracks in the first and second substrates in the inner wound portion can be suppressed or at least mitigated. Therefore, internal short circuits in the electrode assembly can be effectively suppressed or at least mitigated, thereby reducing the risk of fire in the rechargeable battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic perspective view of an electrode assembly according to a first embodiment.

[0020] Figure 2 It shows Figure 1 Schematic diagram of the winding process of the electrode assembly shown in .

[0021] Figure 3 It shows Figure 1 is a top plan view of the expanded state of the first electrode and the second electrode of the electrode assembly shown in .

[0022] Figure 4 yes Figure 3 sectional view of the first electrode and the second electrode shown in .

[0023] Figure 5 yes Figure 1 Schematic cross-sectional view of the electrode assembly shown in .

[0024] Figures 6A to 6C is a top plan view showing a developed state of a first electrode and a second electrode of an electrode assembly according to a second embodiment.

[0025] Figure 7 is a top plan view showing a developed state of a first electrode and a second electrode of an electrode assembly according to a third embodiment.

[0026] Figure 8 is a cross-sectional view of an electrode assembly according to a third embodiment.

[0027] Figure 9 is a top plan view showing a developed state of a first electrode and a second electrode of an electrode assembly according to a fourth embodiment.

[0028] Figure 10 is a cross-sectional view of an electrode assembly according to a fourth embodiment.

[0029] Figure 11 is a top plan view showing a developed state of a first electrode and a second electrode of an electrode assembly according to a fifth embodiment.

[0030] Figure 12 is a top plan view showing a developed state of a first electrode and a second electrode of an electrode assembly according to a sixth embodiment.

[0031] Figures 13 to 17 is a top plan view showing other examples of the first electrode and the second electrode.

[0032] Figure 18 is a graph showing expansion rate experimental results of three types of first electrode samples having different silicon contents in the active material.

[0033] Figure 19 is a perspective view of a rechargeable battery according to an embodiment.

[0034] Figure 20 yes Figure 19 A cross-sectional view of a rechargeable battery is shown in FIG. DETAILED DESCRIPTION

[0035] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. As those skilled in the art will realize, the described embodiments can be modified in various different ways, all without departing from the spirit or scope of the present invention.

[0036] Figure 1 is a schematic perspective view of an electrode assembly 100 according to a first embodiment, Figure 2 It shows Figure 1 Schematic diagram of the winding process of the electrode assembly 100 shown in FIG.

[0037] Reference Figure 1 and Figure 2 The electrode assembly 100 of this embodiment may be a wound electrode assembly for a cylindrical battery. The electrode assembly 100 may include a first electrode 110 and a second electrode 120 that are stacked and wound, with a separator 130 located between the first electrode 110 and the second electrode 120. Each of the first electrode 110, the second electrode 120, and the separator 130 may be in the shape of a strip extending longitudinally along the winding direction.

[0038] The electrode assembly 100 may include a first electrode 110, a separator 130, a second electrode 120, and a separator 130, which are sequentially stacked and then wound around a center pin 10. The first electrode 110 may be closer to the center pin 10 than the second electrode 120, but the arrangement of the first electrode 110 and the second electrode 120 is not limited to this embodiment. The center pin 10 may remain in the electrode assembly 100, or may be separated (e.g., removed) from the electrode assembly 100 after the electrode assembly 100 is wound.

[0039] Figure 3 It shows Figure 1 , a top plan view of the unfolded state of the first electrode 110 and the second electrode 120 of the electrode assembly 100 shown in FIG. Figure 4 yes Figure 3 sectional views of the first electrode 110 and the second electrode 120 shown in FIG.

[0040] Reference Figure 3 and Figure 4 The first electrode 110 may include a first substrate 20, a first composite layer 30 on the first substrate 20, and a first lead tab 40 attached to the first substrate 20. The first composite layer 30 may be spaced apart from both ends of the first substrate 20 by a predetermined distance on each of the inner and outer surfaces of the first substrate 20.

[0041] The second electrode 120 may include a second substrate 50, a second composite layer 60 on the second substrate 50, and a second lead tab 70 attached to the second substrate 50. The second composite layer 60 may contact both ends of the second substrate 50 on each of its inner and outer surfaces.

[0042] The inner surfaces of the first and second substrates 20 and 50 face the center pin 10 or the winding center, while the outer surfaces of the first and second substrates 20 and 50 face away from the center pin 10 or the winding center. The first and second substrates 20 and 50 have inner ends 21 and 51 and outer ends 22 and 52, respectively. The inner ends 21 and 51 are the ends at the start of winding and are located at the winding center of the electrode assembly 100. The outer ends 22 and 52 are the ends at the end of winding and are located at the outermost portion of the electrode assembly 100.

[0043] The length of the second electrode 120 may be shorter than that of the first electrode 110, but the present disclosure is not limited to this embodiment. The inner end 21 of the first substrate 20 and the inner end 51 of the second substrate 50 may be spaced apart from each other along the winding direction. The outer end 22 of the first substrate 20 and the outer end 52 of the second substrate 50 may also be spaced apart from each other along the winding direction.

[0044] The first substrate 20 can be made of a thin metal plate with high electrical conductivity (e.g., copper foil, copper mesh, nickel foil, or nickel mesh). The first composite layer 30 may include an active material, a conductive material, a binder, etc., and may be manufactured through a slurry coating, drying, and compression process. The first substrate 20 is configured to provide a path for the movement of charges generated in the first composite layer 30 and is configured to support the first composite layer 30.

[0045] The active material of the first composite layer 30 may include a material configured to cause reversible intercalation and deintercalation of lithium ions, such as a carbon-based material and silicon. The carbon-based material may include one or more of crystalline carbon and amorphous carbon, and may include one or more of natural graphite and / or artificial graphite. The first electrode 110 may be referred to as a negative electrode.

[0046] The second substrate 50 can be made of a thin metal plate with high electrical conductivity (e.g., aluminum foil or aluminum mesh). The second composite layer 60 can include an active material, a conductive material, a binder, etc., and can be manufactured through a slurry coating, drying, and compression process. The second substrate 50 is configured to provide a path for the movement of charges generated in the second composite layer 60 and is configured to support the second composite layer 60.

[0047] The active material of the second composite layer 60 may include a compound configured to cause reversible intercalation and deintercalation of lithium, and may include one or more of a composite oxide of a metal selected from cobalt, manganese, nickel, and combinations thereof, and lithium. In one or more embodiments, the active material of the second composite layer 60 may include a transition metal oxide such as LiCoO2, LiNiO2, LiMn2O4, Li(NiCoAl)O2, LiFePO4, and / or Li(NiCoMn)O2. The second electrode 120 may be referred to as a positive electrode.

[0048] During charging and discharging of the rechargeable battery, the active material of the first composite layer 30 reversibly intercalates and deintercalates lithium ions from the active material of the second composite layer 60, allowing current to flow to an external circuit. The first composite layer 30 undergoes volume changes by expanding during charging and contracting during discharging, and the first substrate 20 supporting the first composite layer 30 also repeatedly contracts and expands during the charging and discharging processes.

[0049] On each of the inner and outer surfaces of the first substrate 20, the first composite layer 30 may be formed along the length direction ( Figure 3 The active material composition of the first region 31 can be different from that of the second region 32.

[0050] In one or more embodiments, the active material of the first region 31 may not contain silicon, and the active material of the second region 32 may contain less than about 10 wt % silicon. In one or more embodiments, the active material of both the first region 31 and the second region 32 may contain silicon, but the silicon content of the first region 31 may be less than that of the second region 32. The silicon content of the second region 32 may be less than about 10 wt %.

[0051] Silicon helps increase the capacity of rechargeable batteries, but it also increases the shrinkage and expansion of the composite layer. If the active material in the second region 32 contains more than 10 wt% silicon, the shrinkage and expansion of the second region 32 will become excessive. Therefore, the active material in the second region 32 can contain less than 10 wt% silicon. Due to the difference in silicon content between the first region 31 and the second region 32, the shrinkage and expansion of the first region 31 can be smaller than those of the second region 32.

[0052] In addition, the active material of the first region 31 and the active material of the second region 32 may include different types of graphite. In one or more embodiments, the active material of the first region 31 may include artificial graphite, and the active material of the second region 32 may include natural graphite. In one or more embodiments, the active material of the first region 31 may include silicon-free artificial graphite, and the active material of the second region 32 may include natural graphite and less than about 10 wt % silicon.

[0053] In one or more embodiments, the active material of the first region 31 and the active material of the second region 32 may include both artificial graphite and natural graphite. However, the content of artificial graphite in the active material of the first region 31 may be higher than that of natural graphite, and the content of natural graphite in the active material of the second region 32 may be higher than that of artificial graphite.

[0054] Artificial graphite is produced by distilling and heat-treating coal tar from steel production to produce needle coke, grinding the needle coke, graphitizing it at high temperatures, coating the surface, and removing iron. Natural graphite is produced by removing impurities from graphite mined from mines, washing, dehydrating, drying, and mixing it to produce rounded spherical graphite, coating the surface of the spherical graphite with pitch (a byproduct of petroleum refining), and then firing it.

[0055] The shrinkage and expansion rates of a composite layer having a high natural graphite content are higher than those of a composite layer having a high artificial graphite content. Due to the difference in silicon content between the first region 31 and the second region 32, as well as the difference in properties between natural graphite and artificial graphite, the shrinkage and expansion rates of the first region 31 can be smaller than those of the second region 32.

[0056] The first region 31 and the second region 32 may be spaced apart from each other by a distance. The portion of the first substrate 20 not covered by the first composite layer 30 may be referred to as an uncoated region. The three uncoated regions may be on each of the inner and outer surfaces of the first substrate 20. The three uncoated regions may be divided into an inner uncoated region 23 between the inner end 21 and the first region 31, an outer uncoated region 24 between the second region 32 and the outer end 22, and an intermediate uncoated region 25 between the first region 31 and the second region 32. The first lead tab 40 may be attached to the intermediate uncoated region 25 and may protrude toward one side (e.g., the lower side) of the first electrode 110.

[0057] The second composite layer 60 may also be formed on each of the inner and outer surfaces of the second substrate 50 along the length direction ( Figure 3The two regions may include a third region 61 in contact with the inner end 51 and a fourth region 62 in contact with the outer end 52 .

[0058] The active material composition of third region 61 and the active material composition of fourth region 62 can be substantially the same, and the loading level of third region 61 can be lower than that of fourth region 62. The loading level refers to the weight per unit area (coating amount) of second composite layer 60. Due to the difference in loading levels between third region 61 and fourth region 62, the shrinkage and expansion rates of third region 61 can be smaller than those of fourth region 62.

[0059] The third region 61 and the fourth region 62 may be spaced apart from each other by a distance. The portion of the second substrate 50 not covered by the second composite layer 60 may be referred to as an uncoated region. An intermediate uncoated region 53 may be provided on each of the inner and outer surfaces of the second substrate 50. The second lead tab 70 may be attached to the intermediate uncoated region 53 and may protrude toward the other side (e.g., the upper side) of the second electrode 120. In other words, the first lead tab 40 and the second lead tab 70 may protrude toward opposite sides.

[0060] Reference Figures 1 to 4 , the third region 61 may face the first region 31 with the separator between the third region 61 and the first region 31, and the fourth region 62 may face the second region 32 with the separator between the fourth region 62 and the second region 32. The middle uncoated region 53 of the second electrode 120 may face the middle uncoated region 25 of the first electrode 110 with the separator between the middle uncoated region 53 of the second electrode 120 and the middle uncoated region 25 of the first electrode 110.

[0061] To manufacture the first electrode 110, two types of first composite layer slurries having different active material compositions may be prepared, and the two types of first composite layer slurries may be divided into the first region 31 and the second region 32 and applied to produce the first composite layer 30. To manufacture the second electrode 120, one type of second composite layer slurry may be prepared, and the second composite layer slurry may be applied at different loading levels in the third region 61 and the fourth region 62 to produce the second composite layer 60.

[0062] Figure 5 yes Figure 1 Schematic cross-sectional view of the electrode assembly shown in .

[0063] Reference Figures 3 to 5, the electrode assembly 100 may include an inner wound portion 80 and an outer wound portion 90, the inner wound portion 80 including a first region 31 and a third region 61, and the outer wound portion 90 including a second region 32 and a fourth region 62, while surrounding the inner wound portion 80. The intermediate uncoated region 25, 53 may be between the inner wound portion 80 and the outer wound portion 90. The width r1 of the inner wound portion 80 may be approximately the same as or similar to the width r2 of the outer wound portion 90. In one or more embodiments, the width r1 of the inner wound portion 80 may be about 0.8 times to about 1.2 times the width r2 of the outer wound portion 90. As used herein, the width r1 of the inner wound portion 80 and the width r2 of the outer wound portion 90 are widths measured along the radial direction of the electrode assembly 100.

[0064] The middle uncoated region 25 of the first electrode 110 and the middle uncoated region 53 of the second electrode 120 can be located at a position where the width r1 of the inner wound portion 80 and the width r2 of the outer wound portion 90 are approximately or substantially equal. When the first and second electrodes 110 and 120 are unfolded, the middle uncoated regions 25 and 53 can be closer to the inner ends 21 and 51 than to the outer ends 22 and 52. In one or more embodiments, the length of the second region 32 along the length direction (L direction) of the first electrode 110 can be greater than the length of the first region 31 along the length direction (L direction) of the first electrode 110, and the length of the fourth region 62 along the length direction (L direction) of the second electrode 120 can be greater than the length of the third region 61 along the length direction (L direction) of the second electrode 120.

[0065] The electrode assembly 100 of this embodiment can be configured to reduce the volume change of the inner wound portion 80 by reducing the shrinkage and expansion rates of the first region 31 and the third region 61. Furthermore, as the volume change of the inner wound portion 80 is reduced, deformation of the inner wound portion 80 and cracking of the first substrate 20 and the second substrate 50 disposed therein can be suppressed or at least mitigated. As a result, the electrode assembly 100 of this embodiment can effectively suppress (or at least mitigate) internal short circuits and reduce the risk of fire in the rechargeable battery.

[0066] Figures 6A to 6C 1 is a top plan view showing a developed state of the first electrode and the second electrode of the electrode assembly according to the second embodiment. Except for the contents described below, the electrode assembly of the second embodiment has the same or similar configuration as that of the electrode assembly of the first embodiment described above.

[0067] Reference Figures 6A to 6C, there is an imaginary line that divides the first composite layer 30 into four equal parts along the length direction (L direction) of the first substrate 20. The imaginary lines may include a first dividing line L1 corresponding to approximately 1 / 4 point, a second dividing line L2 corresponding to approximately 1 / 2 point, and a third dividing line L3 corresponding to approximately 3 / 4 point. The middle uncoated region 25 of the first electrode 110 may be between the first dividing line L1 and the third dividing line L3.

[0068] exist Figure 6A In the embodiment, the middle uncoated region 25 may be in contact with the first cutting line L1. Figure 6B In the embodiment, the middle uncoated area 25 may be at the second cutting line L2. Figure 6C The middle uncoated region 25 may contact the third cutting line L3. The middle uncoated region 53 of the second electrode 120 may be substantially at the same position as the middle uncoated region 25 of the first electrode 110 to face the middle uncoated region 25 of the first electrode 110.

[0069] If the middle uncoated area 25, 53 and the first and second lead tabs 40 and 70 are closer to the inner ends 21, 51 than the first cutting line L1, or closer to the outer ends 22, 52 than the third cutting line L3, the current movement path will become too long, resulting in reduced current collection efficiency.

[0070] In addition, when the electrode assembly forms a rechargeable battery together with the can and the cap plate, at least one of the first lead tab 40 and the second lead tab 70 may interfere with other components, causing an internal short circuit.

[0071] In the electrode assembly of this embodiment, the intermediate uncoated regions 25 and 53, as well as the first and second lead tabs 40 and 70, may be located between the first and third dividing lines L1 and L3. In this embodiment, current collection efficiency is improved by shortening the current flow path, and internal short circuits are prevented (or at least mitigated) by preventing (or at least mitigating) interference between at least one of the first and second lead tabs 40 and 70 and other components within the rechargeable battery. In embodiments where the intermediate uncoated regions 25 and 53, as well as the first and second lead tabs 40 and 70, are located at the second dividing line L2, the current flow path can be shortened to the greatest extent possible.

[0072] Figure 7 is a top plan view showing a deployed state of a first electrode and a second electrode of an electrode assembly according to a third embodiment, Figure 8 is a cross-sectional view of an electrode assembly according to a third embodiment. Except for the following, the electrode assembly of the third embodiment has the same or similar configuration as that of the electrode assembly of any one of the first and second embodiments described above.

[0073] Reference Figure 7 and Figure 8 In the first electrode 110, the first region 31 and the second region 32 having different active material compositions may be in contact with each other. The second region 32 may be divided into an inner second region 32A and an outer second region 32B. The intermediate uncoated region 25 may be between the inner second region 32A and the outer second region 32B. The position of the intermediate uncoated region 25 may be the same as that of the intermediate uncoated region 25 in the first embodiment or the second embodiment.

[0074] In the second electrode 120, the third region 61 and the fourth region 62 having different load levels may be in contact with each other. The fourth region 62 may be divided into an inner fourth region 62A and an outer fourth region 62B. The middle uncoated region 53 may be between the inner fourth region 62A and the outer fourth region 62B. The middle uncoated region 53 may be at the same position as the middle uncoated region 25 of the first electrode 110 and face the middle uncoated region 25 of the first electrode 110.

[0075] The electrode assembly 100A may include an inner wound portion 80 and an outer wound portion 90, wherein the inner wound portion 80 includes the first region 31 and the third region 61, and the outer wound portion 90 includes the second region 32 and the fourth region 62. A width r4 of the outer wound portion 90 may be greater than a width r3 of the inner wound portion 80, and the intermediate uncoated regions 25 and 53 may be in the outer wound portion 90.

[0076] The first region 31 and the third region 61 may have a length corresponding to at least three turns from the inner ends 21, 51. If the first region 31 and the third region 61 have a length corresponding to less than three turns, the width r3 of the inner wound portion 80 becomes too small, which is less effective in reducing the shrinkage and expansion rates of the electrode assembly, thereby causing deformation due to volume changes in the electrode assembly.

[0077] Figure 9 is a top plan view showing a developed state of a first electrode and a second electrode of an electrode assembly according to a fourth embodiment, Figure 10 1 is a cross-sectional view of an electrode assembly according to a fourth embodiment. Except for the following, the electrode assembly of the fourth embodiment has the same or similar configuration as that of the electrode assembly of any one of the first and second embodiments described above.

[0078] Reference Figure 9 and Figure 10In the first electrode 110, the first region 31 and the second region 32 having different active material compositions may be in contact with each other. The first region 31 may be divided into an inner first region 31A and an outer first region 31B. The intermediate uncoated region 25 may be between the inner first region 31A and the outer first region 31B. The position of the intermediate uncoated region 25 may be the same as that of the intermediate uncoated region 25 in the first embodiment or the second embodiment.

[0079] In the second electrode 120, the third region 61 and the fourth region 62 having different load levels may contact each other. The third region 61 may be divided into an inner third region 61A and an outer third region 61B. The middle uncoated region 53 may be between the inner third region 61A and the outer third region 61B. The middle uncoated region 53 may be at the same position as the middle uncoated region 25 of the first electrode 110 and face the middle uncoated region 25 of the first electrode 110.

[0080] The electrode assembly 100B may include an inner wound portion 80 including the first region 31 and the third region 61, and an outer wound portion 90 including the second region 32 and the fourth region 62. A width r5 of the inner wound portion 80 may be greater than a width r6 of the outer wound portion 90, and the intermediate uncoated regions 25 and 53 may be in the inner wound portion 80.

[0081] The second region 32 and the fourth region 62 may have a length corresponding to at least three turns from the first region 31 and the third region 61 or the outer ends 22, 52. If the second region 32 and the fourth region 62 have a length corresponding to less than three turns, capacity degradation of the rechargeable battery may occur due to the low silicon content of the first composite layer and the low load level of the second composite layer.

[0082] Figure 11 1 is a top plan view showing the expanded state of the first electrode and the second electrode of the electrode assembly according to the fifth embodiment. Except for the contents described below, the electrode assembly of the fifth embodiment has the same or similar configuration as that of the electrode assembly of any of the first and second embodiments described above.

[0083] Reference Figure 11 , the first composite layer 30 of the first electrode 110 may be divided into three or more regions along the length direction (L direction) of the first substrate 20, and the three or more regions may have different active material compositions. Figure 11 , an embodiment in which the first composite layer 30 is divided into a fifth region 33 , a sixth region 34 , and a seventh region 35 is shown, but the number of divided regions is not limited to the illustrated embodiment.

[0084] In one or more embodiments, the active material of the fifth region 33 may not contain silicon, the active materials of the sixth and seventh regions 34 and 35 may contain less than about 10 wt % silicon, and the silicon content of the sixth region 34 may be less than that of the seventh region 35. In one or more embodiments, all of the fifth through seventh regions 33, 34, and 35 may contain silicon, but the silicon content of the fifth region 33 may be less than that of the sixth region 34, and the silicon content of the sixth region 34 may be less than that of the seventh region 35. In one or more embodiments, the silicon content may decrease as the region is closer to the inner end 21.

[0085] In addition, the region closer to the inner end 21 may have an active material with a higher artificial graphite content, and the region closer to the outer end 22 may have an active material with a higher natural graphite content. In one or more embodiments, the active material of the fifth region 33 may include artificial graphite, the active material of the sixth region 34 may include artificial graphite and natural graphite, and the active material of the seventh region 35 may include natural graphite.

[0086] The three or more regions may be in contact with adjacent regions along the length direction (L direction) of the first substrate 20, or may be spaced apart from each other with the intermediate uncoated region 25 therebetween. Figure 11 , an embodiment in which the middle uncoated region 25 is in the sixth region 34 is shown. Due to the differences in the silicon content of the active material and the differences in the content of artificial graphite and natural graphite in the above three or more regions, the shrinkage rate and the expansion rate can be reduced as the region approaches the inner end 21.

[0087] In the second electrode 120 , the second composite layer 60 may also be divided into three or more regions along the length direction (L direction) of the second substrate 50 , and the three or more regions may have different loading levels. Figure 11 , an embodiment is shown in which second composite layer 60 is divided into eighth region 63, ninth region 64, and tenth region 65, but the number of divided regions is not limited to the embodiment shown. The active material composition in eighth region 63, ninth region 64, and tenth region 65 can be the same (or substantially the same), and the loading level can be lower in regions closer to inner end 51.

[0088] The three or more regions may be in contact with adjacent regions along the length direction (L direction) of the second substrate 50, or may be spaced apart from each other with the intermediate uncoated region 53 therebetween. Figure 11, an example is shown in which the middle uncoated region 53 is in the ninth region 64. Due to the difference in load levels in the above three or more regions, the shrinkage rate and the expansion rate can be reduced in the region near the inner end 51.

[0089] Figure 12 1 is a top plan view showing the expanded state of the first electrode and the second electrode of the electrode assembly according to the sixth embodiment. Except for the contents described below, the electrode assembly of the sixth embodiment has the same or similar configuration as that of the electrode assembly of any of the first and second embodiments described above.

[0090] Reference Figure 12 The first composite layer 30 of the first electrode 110 may have an active material composition that continuously changes along the length direction (L direction) of the first substrate 20. In one or more embodiments, the silicon content of the active material in the first composite layer 30 may gradually increase with increasing distance from the inner end 21. The maximum silicon content of the active material may be less than approximately 10 wt%. In addition, the artificial graphite content of the active material in the first composite layer 30 may gradually decrease with increasing distance from the inner end 21, and the natural graphite content of the active material in the first composite layer 30 may gradually increase with increasing distance from the inner end 21.

[0091] In the second electrode 120, the second composite layer 60 may have a gradually varying load level along the length direction (L direction) of the second substrate 50. In one or more embodiments, the load level of the second composite layer 60 may gradually increase as the distance from the inner end 51 increases. Due to the aforementioned characteristics of the first composite layer 30 and the second composite layer 60, the shrinkage rate and expansion rate may decrease as the distance from the inner end 21, 51 decreases.

[0092] The first composite layer 30 may be divided into two regions by the middle uncoated region 25. The second composite layer 60 may also be divided into two regions by the middle uncoated region 53. The positions of the middle uncoated regions 25, 53 may be the same as those of the first embodiment or the second embodiment, respectively.

[0093] Although the above embodiments describe embodiments in which one intermediate uncoated region 25 and one intermediate uncoated region 53 are respectively on the first electrode 110 and the second electrode 120, the intermediate uncoated region may be omitted from at least one of the first electrode and the second electrode, or multiple intermediate uncoated regions may be on the second electrode. Figures 13 to 17 is a top plan view illustrating other embodiments of the first electrode and the second electrode.

[0094] exist Figure 13In the embodiment shown in , the first electrode 110 and the second electrode 120 may include inner uncoated regions 23 and 54 and outer uncoated regions 24 and 55, respectively, and the intermediate uncoated region may be omitted. The first lead tab 40 may be on the outer uncoated region 24 of the first electrode 110. The second lead tab 70 may be on the inner uncoated region 54 of the second electrode 120.

[0095] exist Figure 14 and Figure 15 In the embodiment shown in FIG, the first electrode 110 may include an inner uncoated region 23 and an outer uncoated region 24, and the middle uncoated region may be omitted. The second electrode 120 may include one middle uncoated region 53. The first lead tab 40 may be on the outer uncoated region 24 of the first electrode 110 (see FIG. Figure 14 ), or may be on each of the inner uncoated region 23 and the outer uncoated region 24 (see Figure 15 ).

[0096] exist Figure 16 In the embodiment shown in , the first electrode 110 may include an inner uncoated region 23 and an outer uncoated region 24, and the intermediate uncoated region may be omitted. The second electrode 120 may include two intermediate uncoated regions 53. The first lead tab 40 may be on each of the inner uncoated region 23 and the outer uncoated region 24 of the first electrode 110. The second lead tab 70 may be on each of the two intermediate uncoated regions 53 provided on the second electrode.

[0097] exist Figure 17 In the embodiment shown in , the first electrode 110 may include an inner uncoated region 23, an outer uncoated region 24, and a middle uncoated region 25. The second electrode 120 may include two middle uncoated regions 53. The first lead tab 40 may be on each of the inner uncoated region 23, the outer uncoated region 24, and the middle uncoated region 25, and the two second lead tabs 70 may be in the two middle uncoated regions 53.

[0098] exist Figures 13 to 17 In all of the embodiments shown in , the first composite layer 30 may be divided into a plurality of regions having different active material compositions, or the active material composition may vary continuously along the length direction. In addition, in the second composite layer 60, the loading level may be divided into a plurality of regions, or the loading level may vary continuously along the length direction. Figures 13 to 17 , it is shown that the first composite layer 30 is divided into the first region 31 and the second region 32 , and the second composite layer 60 is divided into the third region 61 and the fourth region 62 , but the present disclosure is not limited thereto.

[0099] Figure 18 This graph shows the expansion rate test results for three types of first electrode samples with different silicon contents in the active material. The three first electrode samples include a first sample with a silicon content of approximately 1.03 wt%, a second sample with a silicon content of approximately 1.35 wt%, and a third sample with a silicon content of approximately 1.83 wt%. Aside from the silicon content, the active material compositions of the first through third samples were identical.

[0100] Reference Figure 18 , it can be seen that all three types of first electrode samples show a sharp increase in expansion ratio when the state of charge (SOC) is 100 compared to when the SOC is 0, and the expansion ratio gradually increases with the increase in the number of charge and discharge cycles. Figure 18 In all the results shown in , the expansion ratio is proportional to the silicon content. The electrode assembly of the above embodiment can reduce the volume change of the inner winding portion by differentiating the silicon content of the first composite layer active material along the length direction (winding direction) of the first electrode.

[0101] Figure 19 is a perspective view of a rechargeable battery according to an embodiment, and Figure 20 yes Figure 19 A cross-sectional view of a rechargeable battery is shown in FIG.

[0102] Reference Figure 19 and Figure 20 , the rechargeable battery of this embodiment may include an electrode assembly 100, a can 200 that houses the electrode assembly 100 together with an electrolyte, and a cap assembly 300 coupled to an open end of the can 200 to seal the can 200. The electrode assembly 100 is the same as that described above with reference to FIG. Figures 1 to 17 One of the electrode assemblies described.

[0103] The can 200 includes an open top to accommodate the electrode assembly 100. The can 200 may include a circular bottom 210 and a cylindrical side 220 connected to the edge of the bottom 210. When the rechargeable battery is inverted, the bottom 210 may be referred to as the top. The can 200 may be made of, for example, stainless steel, aluminum, and / or an aluminum alloy.

[0104] The first insulating plate 410 may be on the lower side of the electrode assembly 100, and the second insulating plate 420 may be on the upper side of the electrode assembly 100. The first lead tab 40 may be led out through the tab opening 401 in the first insulating plate 410 and coupled to the bottom 210 of the can 200. The second lead tab 70 may be led out through the tab opening 402 in the second insulating plate 420 and coupled to the cap assembly 300. In addition to the tab openings 401 and 402, the first insulating plate 410 and the second insulating plate 420 may be provided with an opening for electrolyte injection and an opening for gas exhaust.

[0105] The beading portion 230 and the crimping portion 240 may be on the side portion 220 of the can 200. The beading portion 230 is a recessed portion extending inwardly toward the interior of the can 200 and is configured to reduce movement of the electrode assembly 100. The crimping portion 240 is a portion where the open end of the side portion 220 is vertically bent toward the interior of the can 200 and is configured to fix the cap assembly 300 together with the beading portion 230.

[0106] The cap assembly 300 may be fixed between the curling portion 230 and the crimping portion 240 by the insulating gasket 500 to seal the can 200. The cap assembly 300 may include an upper cap 310, a safety vent 320, a lower cap 330, an insulating member 340, and a sub-plate 350, but the present disclosure is not limited thereto and many variations are possible.

[0107] The upper cover 310 may be located at the uppermost side of the cover assembly 300. The upper cover 310 may include a terminal portion 311 that protrudes convexly upward and is connected to an external circuit, and an outlet port 312 configured to exhaust gas may be located around the terminal portion 311. A safety vent 320 may be located below the upper cover 310. The safety vent 320 may include a protrusion 321 that protrudes convexly downward and is connected to the sub-board 350, and at least one recess 322 located around the protrusion 321.

[0108] Rapid charging and discharging or abnormal operation of a rechargeable battery generates heat, and the electrolyte evaporates due to the heat, generating gas. The protrusion 321 can be configured to deform upward in response to internal pressure and separate from the sub-plate 350, and the safety vent 320 can be configured to be cut along the notch 322. The cut safety vent 320 can prevent the rechargeable battery from exploding by releasing (exhausting) gas to the outside.

[0109] The lower cover 330 may be below the safety vent 320. A first opening 331 for exposing the protrusion 321 of the safety vent 320 and a second opening 332 for exhausting gas may be in the lower cover 330. The insulating member 340 has a ring shape and may be between the safety vent 320 and the lower cover 330.

[0110] The sub-plate 350 may be below the lower cover 330. The sub-plate 350 may be fixed to the lower surface of the lower cover 330 to block the first opening 331 of the lower cover 330, and the protrusion 321 of the safety vent 320 may be fixed to the sub-plate 350. The second lead tab 70 led out from the electrode assembly 100 may be fixed to the sub-plate 350.

[0111] Can 200 is charged to the same polarity as the first electrode of electrode assembly 100 via first lead tab 40 and can serve as a terminal (negative terminal) for the first electrode. Cap assembly 300 is charged to the same polarity as the second electrode of electrode assembly 100 via second lead tab 70 and can serve as a terminal (positive terminal) for the second electrode. Can 200 and cap assembly 300 are insulated from each other by insulating gasket 500.

[0112] In the above-described rechargeable battery, the electrode assembly 100 is configured to reduce the volume change of the inner wound portion 80. Reducing the volume change of the inner wound portion 80 can prevent (or at least mitigate) internal short circuits in the electrode assembly 100 by suppressing (or at least reducing) deformation of the inner wound portion 80 and cracks in the substrate. Therefore, the safety of the rechargeable battery can be improved by reducing the risk of fire caused by internal short circuits in the electrode assembly 100.

[0113] While the disclosure has been described in connection with what are presently considered to be practical embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. An electrode assembly, comprising: diaphragm; a first electrode; as well as a second electrode; wherein the first electrode and the second electrode are stacked and wound with the separator located between the first electrode and the second electrode; The first electrode includes a first substrate and a first composite layer provided on the first substrate. The first composite layer is divided into at least two regions along the length direction of the first substrate, and The at least two regions of the first composite layer have different active material compositions.

2. The electrode assembly according to claim 1, wherein The first base includes an inner end and an outer end, and The silicon content of the active material of the at least two regions decreases in a direction toward the inner end.

3. The electrode assembly according to claim 2, wherein: The at least two regions include artificial graphite and natural graphite, and The content of artificial graphite increases and the content of natural graphite decreases in a direction toward the inner end.

4. The electrode assembly according to claim 2, wherein: The at least two regions include a first region close to the inner end and a second region close to the outer end, The active material of the second region comprises less than 10 wt % silicon, and The active material of the first region contains no silicon or a lower silicon content than the silicon content of the second region.

5. The electrode assembly according to claim 4, wherein The active material of the first region includes artificial graphite, and The active material of the second region includes natural graphite.

6. The electrode assembly according to claim 4, further comprising an intermediate uncoated region between the first region and the second region, and in, The first electrode also includes a first lead tab attached to the middle uncoated region.

7. The electrode assembly according to claim 6, wherein: The first composite layer includes a first imaginary dividing line, a second imaginary dividing line, and a third imaginary dividing line that divide the first composite layer into four equal parts along the length direction of the first substrate, and Wherein, the middle uncoated area is between the first imaginary dividing line and the third imaginary dividing line.

8. The electrode assembly according to claim 4, wherein: the first region and the second region are in contact with each other, The length of the first region is smaller than the length of the second region, and The length of the first region corresponds to at least three turns from the inner end.

9. The electrode assembly according to claim 4, wherein: the first region and the second region are in contact with each other, The length of the second region is smaller than the length of the first region, and The length of the second region corresponds to at least three turns from the outer end.

10. An electrode assembly, comprising: diaphragm; a first electrode; as well as the second electrode, wherein the first electrode and the second electrode are stacked and wound with the separator located between the first electrode and the second electrode; Wherein, the first electrode includes a first substrate and a first composite layer, Wherein, the second electrode includes a second substrate and a second composite layer, The first composite layer is divided into at least two regions along the length direction of the first substrate. The second composite layer is divided into at least two regions along the length direction of the second substrate. wherein the at least two regions of the first composite layer have different active material compositions, and The at least two regions of the second composite layer have different load levels.

11. The electrode assembly according to claim 10, wherein: Each of the first substrate and the second substrate includes an inner end and an outer end, The silicon content of the active material in the at least two regions of the first composite layer decreases in a direction toward the inner end, and The load levels of the at least two regions of the second composite layer decrease in a direction toward the inboard end.

12. The electrode assembly according to claim 11, wherein The at least two regions of the first composite layer include artificial graphite and natural graphite, and The content of artificial graphite increases and the content of natural graphite decreases in a direction toward the inner end.

13. The electrode assembly according to claim 11, wherein The at least two regions of the first composite layer include a first region near the inner end and a second region near the outer end, The active material of the second region comprises natural graphite and less than 10 wt % silicon, The active material of the first region contains artificial graphite and does not contain silicon or has a silicon content lower than that of the second region.

14. The electrode assembly according to claim 13, wherein: The first electrode further includes a middle uncoated region between the first region and the second region and a first lead tab attached to the middle uncoated region of the first electrode, The at least two regions of the second composite layer include a third region corresponding to the first region and a fourth region corresponding to the second region, and The second electrode further includes a middle uncoated region between the third region and the fourth region and a second lead tab attached to the middle uncoated region of the second electrode.

15. The electrode assembly according to claim 14, wherein The first composite layer includes a first imaginary dividing line, a second imaginary dividing line, and a third imaginary dividing line that divide the first composite layer into four equal parts along the length direction of the first substrate, and The middle uncoated region of the first electrode and the middle uncoated region of the second electrode are between the first imaginary dividing line and the third imaginary dividing line.

16. A rechargeable battery, comprising: An electrode assembly comprising a first electrode and a second electrode that are stacked and wound, and a separator located between the first electrode and the second electrode, the electrode assembly comprising an inner wound portion and an outer wound portion surrounding the inner wound portion; a tank accommodating the electrode assembly and the electrolyte in an interior space of the tank; as well as a cap assembly coupled to the can and sealing the can, Wherein, the first electrode includes a first substrate and a first composite layer, Wherein, the second electrode includes a second substrate and a second composite layer, wherein the silicon content of the first composite layer in the inner winding portion is lower than that in the outer winding portion, and The load level of the second composite layer in the inner winding portion is lower than the load level in the outer winding portion.

17. The rechargeable battery according to claim 16, wherein The first composite layer in the inner winding portion comprises artificial graphite, and Wherein, the first composite layer in the outer winding portion comprises natural graphite.

18. The rechargeable battery according to claim 16, further comprising: a middle uncoated region located between the inner winding portion and the outer winding portion; as well as a first lead tab and a second lead tab attached to the middle uncoated area, The first imaginary dividing line, the second imaginary dividing line and the third imaginary dividing line divide the first composite layer into four equal parts along the length direction of the first substrate, and Wherein, the middle uncoated area is located between the first imaginary dividing line and the third imaginary dividing line.

19. The rechargeable battery according to claim 16, wherein The width of the inner winding portion is smaller than the width of the outer winding portion, said inner coiled portion having a length corresponding to at least three turns, The middle uncoated region is located at the outer winding portion, and A first lead tab and a second lead tab are attached to the middle uncoated area.

20. The rechargeable battery according to claim 16, wherein The width of the outer winding portion is smaller than the width of the inner winding portion, said outer winding portion having a length corresponding to at least three turns, The middle uncoated area is located at the inner winding portion, and A first lead tab and a second lead tab are attached to the middle uncoated area.

Images