Patent Application
20250149619
This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0151072 filed in the Korean Intellectual Property Office on Nov. 3, 2023, the entire contents of which are incorporated herein by reference.
Embodiments relate to a rechargeable battery. More particularly, embodiments of the present disclosure relate to an electrode assembly of a cylindrical battery.
A rechargeable battery is used for a variety of purposes, such as powering a small electronic device such as a mobile phone and a laptop computer, and powering a motor for a transportation vehicle such as an electric vehicle and a hybrid vehicle. In the latter case, a battery module system combining a plurality of cylindrical rechargeable batteries can be used, and in this case, cylindrical rechargeable batteries are trending to enlarge a diameter of the electrode assembly to secure large capacity.
As the diameter of the electrode assembly increases, the pressure applied to a center of the electrode assembly increases during a process of winding a separator and electrodes at high speed, and thus a diameter of a core needs be enlarged to withstand high pressure. However, expanding the core diameter leads to a decrease in the capacity of the rechargeable battery. In addition, the volume of the electrode assembly increases during charging, and as the diameter of the electrode assembly increases, the pressure due to expansion increases. This may cause deformation or cracks in the electrode assembly, which may lead to an internal short circuit of the rechargeable battery.
Embodiments include an electrode assembly, including a first electrode assembly having a first plurality of windings of a first laminate, the first laminate including a first electrode, a separator, and a second electrode, a middle portion surrounding the first electrode assembly and a second electrode assembly that surrounds the middle portion, the second electrode assembly having a second plurality of windings of a second laminate, the second laminate including a first electrode, a separator and a second electrode, wherein the middle portion may adjust a gap between the first electrode assembly and the second electrode assembly according to pressure changes.
The first plurality of windings of the first laminate may surround a first core, the second plurality of windings of the second laminate may surround a second core, and the first electrode assembly and the middle portion may be disposed in an empty space in a center of the second electrode assembly where the second core is removed.
The first laminate may be a stacking structure having a first electrode, a first separator, a second electrode, and a second separator, the middle portion may include a two-layered separator that may be integrally connected with the first separator and the second separator included in the first laminate, and the middle portion may have multiple windings of the two-layered separator.
The middle portion may include an adhesive tape covering an end of the first laminate, and the middle portion may have multiple windings of the adhesive tape.
The first plurality of windings of the first laminate may surround a first core, the middle portion may surround a second core, the second plurality of windings of the second laminate may surround the middle portion, and the first electrode assembly may be in an empty space in a center of the middle portion where the second core is removed.
The second laminate may be a stacking structure having a first electrode, a first separator, a second electrode, and a second separator, the middle portion may include a two-layered separator integrally connected to the first separator and the second separator included in the second laminate, and the middle portion may have a plurality of windings of the two-layered separator.
Embodiments include an electrode assembly, the electrode assembly including a first electrode assembly having a first plurality of windings of a first laminate, the first laminate including a first electrode, a separator, and a second electrode, a middle portion surrounding the first electrode assembly, and a second electrode assembly that surrounds the middle portion, the second electrode assembly having a second plurality of windings of a second laminate, the second laminate including a first electrode, a separator and a second electrode, wherein the first laminate and the second laminate are disposed separately from each other, and the middle portion may be integrally connected with one of the first laminate and the second laminate.
The first laminate may be a stacking structure having a first electrode, a first separator, a second electrode and a second separator, and the middle portion may include a two-layered separator integrally connected with the first separator and the second separator included in the first laminate.
The first plurality of windings of the first laminate may surround a first core, and the middle portion may have multiple windings of the two-layered separator.
The second laminate may be a stacking structure of a first electrode, a first separator, a second electrode, and a second separator, and the middle portion may include a two-layered separator integrally connected with the first separator and the second separator included in the second laminate.
A plurality of windings of the two-layered separator may surround a second core, the second plurality of windings of the second laminate may surround the middle portion, and the first electrode assembly may be disposed in an empty space in a center of the middle portion where the second core is removed.
The second electrode of each of the first laminate and the second laminate may include a second substrate and a second composite material layer disposed on the second substrate, and the second composite material layer of the first laminate and the second composite material layer of the second laminate are different in at least one of silicon content and density.
The second electrode assembly may have an N/P ratio that is smaller than a N/P ratio of the first electrode assembly.
Embodiments include a rechargeable battery, the rechargeable battery including an electrode assembly, a can that accommodates the electrode assembly in an inner space thereof and a cap plate that is coupled to an end of an open side of the can and seals the can, wherein the electrode assembly includes a first electrode assembly having a plurality of windings of a first laminate, a middle portion surrounding the first electrode assembly, and a second electrode assembly surround the middle portion and having a plurality of windings of a second laminate, and wherein the middle portion adjusts a gap between the first electrode assembly and the second electrode assembly according to pressure changes.
The first electrode assembly and the second electrode assembly may each include a first uncoated region extended to one side and a second uncoated region extended to the other (opposite) side, and each of the first uncoated region and the second uncoated region may be bent toward a center of the first electrode assembly, and the first uncoated region of the second electrode assembly may be in contact with the first uncoated region of the first electrode assembly, and the second uncoated region of the second electrode assembly may be in contact with the second uncoated region of the first electrode assembly.
The rechargeable battery may further include a first current collecting plate fixed to the first uncoated region of the electrode assembly, a rivet terminal installed in a terminal hole provided in the can via an insulator and may be coupled to the first current collecting plate and a second current collecting plate fixed to the second uncoated region of the electrode assembly and includes a conductive portion that is in close contact to an interior wall of the can.
Features will become apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which:
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art.
In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that if a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that if a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that if a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout.
The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure are shown. As those of ordinary skill in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present disclosure.
Referring to
The first electrode assembly 110 is formed of a band-shaped first laminate 210 wound in a jelly roll shape around a first core 140. The first laminate 210 may include a first electrode 10, a separator 30, a second electrode 20, and a separator 30 that are sequentially stacked, and may be wound, for example, five or more times around the first core 140. In the first laminate 210, the positions of the first electrode 10 and the second electrode 20 may be switched.
The middle portion 120 may be disposed outside the first electrode assembly 110 while surrounding the first electrode assembly 110. The second electrode assembly 130 may be disposed outside the middle portion 120 while surrounding the middle portion 120. In this way, the first electrode assembly 110, the middle portion 120, and the second electrode assembly 130 may be sequentially disposed along the radial direction centered on the first core 140.
The second electrode assembly 130 may be a band-shaped second laminate 220 wound around a second core 150 in a jelly roll form, and the second core 150 may thereafter be removed. The second laminate 220 may include a first electrode 40, a separator 60, a second electrode 50, and a separator 60 that are sequentially stacked, and may be wound, for example, five or more times around the second core 150. In the second laminate 220, the positions of first electrode 40 and second electrode 50 may be switched.
A diameter d1 of the second core 150 and an interior diameter of the second electrode assembly 130 after the second core 150 is removed, may be slightly larger than an exterior diameter d2 of the middle portion 120. After the second core 150 is removed from the second electrode assembly 130, the first electrode assembly 110 and the middle portion 120 may be accommodated in an internal space of the second electrode assembly 130 to form the electrode assembly 100 together with the second electrode assembly 130. In some embodiments, the first core 140 may remain or, in other embodiments, may be removed. The electrode assembly 100 may be accommodated in an inner space of a can, which will be described later, together with an electrolyte solution.
The first electrodes 10 and 40 of the first and second laminates 210 and 220, respectively, may include first substrates 11 and 41, and first composite material layers 12 and 42 may be disposed on the first substrates 11 and 41, respectively. The composite material layers 12 and 42 may be disposed on both sides of the remaining region except for one (upper) edge of first substrates 11 and 41. The second electrodes 20 and 50 of the first and second laminates 210 and 220 respectively may include second substrates 21 and 51 and second composite material layers 22 and 52 disposed on the second substrates 21 and 51. The second composite material layers 22 and 52 may be disposed on both sides of the remaining region except for the other (lower) edge of second substrates 21 and 51.
In a lithium ion rechargeable battery according to one or more embodiments, the first substrates 11 and 41 may include aluminum foil, and the first composite material layers 12 and 42 may include a transition metal oxide such as LiCoO2, LiNiO2, LiMn2O4, Li(NiCoAl)O2, LiFePO4, Li(NiCoMn)O2, and the like, a conductive material, a binder, and the like. The second substrates 21 and 51 may include, for example, copper foil or nickel foil, and the second composite material layers 22 and 52 may include, for example, graphite, silicon, a conductive material, and a binder. The first electrodes 10 and 40 may be referred to as a positive electrode, and the second electrodes 20 and 50 may be referred to as a negative electrode.
The separators 30 and 60 may be made of a porous material, or may be made of a porous material with a coating layer disposed on at least one side. The porous material may include one or more of polyethylene, polypropylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyester, polycarbonate, and polyimide. The coating layer may include a binder and may further include inorganic particles. The binder may include a polyvinylidene fluoride-based compound. The inorganic particles may include one or more of Al2O3, BaSO4, MgO, Mg(OH)2, SiO2, TiO2, ZnO, SnO2, NiO, and GaO. The separators 30 and 60 may insulate the first electrodes 10 and 40 and the second electrodes 20 and 50 while allowing movement of lithium ions.
Referring to
The middle portion 120 may include a two or more-layered separator, and may include the two or more-layered separators wound one or more times. For example, the middle portion 120 may include a two-layered separator 30a, and the two-layered separator 30a may be connected to two separators 30 belonging to the first laminate 210.
In some embodiments, the two separators 30 belonging to the first laminate 210 may extend outward beyond the first electrode 10 and the second electrode 20 to form the separator 30a of the middle portion 120. The middle portion 120 may be formed of the separator 30a and has excellent electrolyte solution impregnation and changes in thickness quickly according to pressure changes, and thus it is advantageous for precisely controlling the gap between the first and second electrode assemblies 110 and 130.
The number of turns of the middle portion 120 may be, for example, between 1 and 10 times, and preferably between 1 and 3 times. If the number of turns of the middle portion 120 is one or more, the middle portion 120 may surround the entire outer surface of the first electrode assembly 110. As the number of turns of the middle portion 120 increases, a gap control function becomes better, but the capacity of the electrode assembly decreases. If the number of turns of the middle portion 120 is 3 or less, the capacity of the electrode assembly 100 may be increased while implementing an appropriate gap adjustment function.
In general, rechargeable batteries tend to enlarge the diameter of the electrode assembly to secure large capacity. However, simply enlarging the diameter of the electrode assembly increases the pressure applied to the center of the electrode assembly during the process of winding the laminate at high speed, and thus the diameter of the core may be enlarged to withstand high pressure. However, expanding the core diameter causes a decrease in the capacity of the rechargeable battery.
In the electrode assembly 100 of
In addition, in a typical rechargeable battery, the electrode assembly may undergo repeated volume changes that expand during charging and contract during discharge due to the secondary composite material layer, and as the diameter of the electrode assembly increases, the pressure applied to the center of the electrode assembly increases due to expansion. As a result, deformation such as folding or cracks may occur in the electrode assembly, which may lead to an internal short circuit of the rechargeable battery.
In the electrode assembly 100 of
Therefore, the electrode assembly 100 of
In the electrode assembly 100 of the above-described configuration, the second composite material layer 22 of the first laminate 210 and the second composite material layer 52 of the second laminate 220 may be manufactured to have different expansion characteristics. For example, the second composite material layer 22 of the first laminate 210 and the second composite material layer 52 of the second laminate 220 may be manufactured differently in at least one of silicon content and density. In general, the silicon content and density of the second composite material layers 22 and 52 may be in a proportional relationship with the degree of expansion if charged.
Since the inner portion of the second electrode assembly 130 facing the middle portion 120 is not mechanically fixed to a specific portion, the inner portion of the second electrode assembly 130 may be deformed or cracked upon expansion along the length direction (circumferential direction) of the second laminate 220. If expansion along the length direction (circumference direction) of second laminate 220 needs to be suppressed, the second composite material layer 52 of the second laminate 220 may have a lower silicon content than the second composite material layer 22 of the first laminate 210 or may have lower density than the second composite material layer 22 of the first laminate 210.
In some embodiments, if the first core 140 is removed, the first electrode assembly 110 may have an empty space inside. In this case, wrinkles or cracks may occur at an inner end of the first electrode assembly 110 if the first electrode assembly 110 expands. If the expansion of the first electrode assembly 110 needs to be suppressed, the second composite material layer 22 of the first laminate 210 may have a lower silicon content than the second composite material layer 52 of the second laminate 220 or may have lower density than the second composite material layer 52 of the second laminate 220.
The difference in silicon content of the second composite material layers 22 and 52 or the density of the second composite material layers 22 and 52 is not limited to the above examples, and if the degree of expansion of a specific portion needs to be controlled according to the position characteristics of the electrode assembly 100, the silicon content of the second composite material layers 22 and 52 or the density of the second composite material layers 22 and 52 can be adjusted in various ways.
In addition, in the electrode assembly 100 of the above-described configuration, the first electrode assembly 110 and the second electrode assembly 130 may be manufactured to have different N/P ratios. The N/P ratio is the capacity of the second electrode divided by the capacity of the first electrode, and a typical rechargeable battery has an N/P ratio greater than 1. As the diameter of the electrode assembly increases to secure large capacity of the rechargeable battery, the N/P ratio needs to be increased to balance the first electrode and the second electrode at the inner edge (edge where winding begins) and the outer edge (edge where winding ends).
In the electrode assembly 100 of
The electrode assembly 100 of
Referring to
After the first electrode assembly 110 and the middle portion 120 are accommodated in the inner space of the second electrode assembly 130, the first uncoated regions 13 and 43 may be bent inward toward the first core (not shown) and thus may be overlapped with neighboring first uncoated regions 13 and 43. The second uncoated regions 23 and 53 may also bend inward toward the first core and overlap with neighboring second uncoated regions 23 and 53. A plurality of cutout lines may be positioned in the first and second uncoated regions 13, 43, 23, and 53 such that the first and second uncoated regions 13, 43, 23, and 53) can be easily bent (e.g., where the bend is desired). The first uncoated regions 13 and 43 and the second uncoated regions 23, and 53 each may be overlapped and pressed by bending to form a flat surface.
In this case, the first uncoated region 43 of the second electrode assembly 130 may contact the first uncoated region 13 of the first electrode assembly 110, and the second uncoated region 53 of the second electrode assembly 130 may contact the second uncoated region 23 of the first electrode assembly 110. In this case, the first electrodes 10 and 40 of the first and second electrode assemblies 110 and 130 may be electrically conducted, and the second electrodes 20 and 50 of the first and second electrode assemblies 110 and 130 may be electrically conducted.
Referring to
A diameter d3 of the second core 150 and an interior diameter of the middle portion 160 after the second core 150 is removed may be slightly larger than an exterior diameter d4 of the first electrode assembly 110. After the second core 150 is removed from the middle portion 160 and the second electrode assembly 130, the first electrode assembly 110 may be accommodated in an inner space of the middle portion 160, thereby forming an electrode assembly 100A together with the middle portion 160 and the second electrode assembly 130.
The middle portion 160 may be formed of a two-layered separator 30b, and the two-layered separator 30b may be connected to two separators 60 belonging to the second laminate 220. That is, the two separators 60 belonging to the second laminate 220 may extend inward beyond the first electrode 40 and the second electrode 50 to form the separator 30b of the middle portion 160.
Referring to
A thickness of the adhesive tape may be equal to or greater than thicknesses of separators 30 and 60 included in first and second laminates 210 and 220. The middle portion 170 formed of the adhesive tape may cover an outer edge (edge where winding ends) of the first laminate 210 to prevent the first laminate 210 from unwinding. Therefore, in a process of inserting the first electrode assembly 110 and the middle portion 170 into a second electrode assembly 130 from which a second core (not shown) has been removed, the assembling can be facilitated.
In the case of the embodiment of
Referring to
The can 310 may have a shape with one side open (e.g., the lower side in the orientation of
A terminal hole may be disposed in a center of the top portion 311, and the rivet terminal 350 may be installed in the terminal hole through a first insulator 361. The first current collecting plate 330 may be fixed to first uncoated regions 13 and 43 of the electrode assembly 100, and the second current collecting plate 340 may be fixed to the second uncoated regions 23 and 53 of the electrode assembly 100. The rivet terminal 350 may be combined with the first current collecting plate 330, and may be charged to the same polarity as first electrodes 10 and 40 by the first current collecting plate 330 and function as a first terminal (e.g., a positive terminal).
The first insulator 361 may insulate the rivet terminal 350 and the top portion 311 and may seal the terminal hole to prevent leakage of the electrolyte solution. In some embodiments, a second insulator 362 may be disposed between an inner surface of the top portion 311 and the first current collecting plate 330 to insulate the top portion 311 and the first current collecting plate 330.
The cap plate 320 may be disposed on the outside (e.g., the lower side) of the second current collecting plate 340 and may be coupled to an end of a side portion 312 via a third insulator 363. A notch groove 321 may be disposed on an inner surface of the cap plate 320. The notch groove 321 may have a V-shaped cross-section and may have a circular arc shape on a plane (if viewing the target object from above).
The internal temperature of a rechargeable battery may rise due to various causes such as rapid charge and discharge, external impact, and exposure to a high temperature environment, and the internal pressure may rise due to gasification of the electrolyte solution, and the like. If the internal pressure of the rechargeable battery 300 increases, the cap plate 320 may break around the notch groove 321 and internal gas may be discharged.
The side portion 312 of the can 310 may include a beading portion 313 and a crimping portion 314. The beading portion 313 may be a portion of the side portion 312 deformed concavely toward the inside of the side portion 312, and the crimping portion 314 may be a portion where an end of the side portion 312 is bent vertically toward the inside of the side portion 312.
An edge of the cap plate 320 may be pressed between the beading portion 313 and the crimping portion 314 via the third insulator 363, and the cap plate 320 may be firmly fixed to the end of the side portion 312 by the beading portion 313 and the crimping portion 314. The cap plate 320 is insulated from the first electrodes 10 and 40 and the second electrodes 20 and 50 and may be electrically non-polar.
The second current collecting plate 340 may include a conductive portion 341 in close contact with an inner surface of the beading portion 313. The conductive portion 341 may be provided in plural numbers along an edge of the second current collecting plate 340. The can 310 may be charged to the same polarity as the second electrodes 20 and 50 by the conductive portion 341 and may function as a second terminal (e.g., a negative terminal). The rechargeable battery 300 may be provided in plural, and the plurality of rechargeable batteries may be connected by a bus bar (not shown) to form a battery module system.
The rechargeable battery 300 may increase capacity by enlarging the diameters of the electrode assembly 100 and the can 310, and suppresses deformation or cracks due to pressure during expansion of the electrode assembly 100 by using the middle portion 120 of the electrode assembly 100, and thus internal short circuits can be prevented, thereby improving long-term durability.
The present disclosure provides an electrode assembly that implements large capacity by enlarging a diameter of an electrode assembly to prevent capacity reduction due to a core, and prevents internal short circuits by suppressing deformation or crack of the electrode assembly due to pressure during expansion, and a rechargeable battery provided with the electrode assembly.
According to the embodiments, an electrode assembly is advantageous in securing large capacity by enlarging the entire diameter due to individual winding of the first laminate and second laminate, and capacity reduction due to the core does not occur. In addition, the electrode assembly may suppress the occurrence of deformation or cracks in the electrode assembly by the middle portion even if volume expansion occurs during charging, and can effectively prevent internal short circuits of the rechargeable battery.
While this disclosure has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the embodiments are not limited to those disclosed. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0151072 | Nov 2023 | KR | national |
