Electrode assembly

Abstract

The electrode assembly includes: a stack of positive electrodes; a pair of separators on each side of each positive electrode in the stack of positive electrodes; and at least one negative electrode in a strip shape, the at least one negative electrode being repeatedly bent around the stack of the separator and the positive electrode.

Description

Technical Field

[0001] Embodiments relate to electrode assemblies. Background Art

[0002] As technology develops and demand for mobile devices increases, demand for rechargeable batteries as energy sources is rapidly increasing.

[0003] Rechargeable batteries can be manufactured by placing an electrode assembly, which is formed by arranging electrodes on each side of a separator and winding it into a jelly roll form, or by stacking sheet-shaped electrodes and separators, into a case with an electrolyte solution and sealing the case with a cap assembly. Summary of the Invention

[0004] An embodiment can be achieved by providing an electrode assembly comprising: a stack of positive electrodes; a pair of separators on each side of each positive electrode in the stack of positive electrodes; and at least one negative electrode in the form of a strip that is repeatedly bent around the separator and the stack of positive electrodes.

[0005] The positive electrode and the separator may each have a sheet shape.

[0006] The at least one negative electrode may be repeatedly bent in a first direction and a second direction, first surfaces of the at least one negative electrode face each other in the first direction, and second surfaces of the at least one negative electrode face each other in the second direction.

[0007] The at least one negative electrode may include a substrate and a negative active material layer on the substrate, and the substrate of the at least one negative electrode may be repeatedly bent.

[0008] Each positive electrode in the stack of positive electrodes may include a first positive active material layer, and the negative active material layer may overlap the first positive active material layer.

[0009] Each separator in the pair of separators may have an area larger than an area of ​​each positive electrode in the stack of positive electrodes.

[0010] The edges of the paired diaphragms may be bonded to each other.

[0011] At least one negative electrode may include a first negative electrode and a second negative electrode that overlap and bend each other, and the electrode assembly may further include a first belt-type separator, a belt-type positive electrode, and a second belt-type separator between the first negative electrode and the second negative electrode and bent together with the first negative electrode and the second negative electrode.

[0012] The strip-type positive electrode may include a substrate and second positive active material layers on the substrate of the strip-type positive electrode at regular intervals, and the substrate of the strip-type positive electrode between the second positive active material layers may be bent.

[0013] The electrode assembly may further include: a pair of external positive electrodes respectively overlapping outermost surfaces of the bent negative electrode; and external separators on respective sides of each of the pair of external positive electrodes.

[0014] Each positive electrode and each separator in the stack of positive electrodes may surround one bent portion of at least one negative electrode once and cover one bent portion of the at least one negative electrode on a side of the electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0016] Figure 1 A cross-sectional view of an electrode assembly according to an embodiment is shown.

[0017] Figure 2 Show expanded Figure 1 electrode assembly.

[0018] Figure 3 and Figure 4 A cross-sectional view of an electrode assembly according to another embodiment is shown. DETAILED DESCRIPTION

[0019] Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, example embodiments 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.

[0020] In the accompanying drawings, the dimensions of layers and regions may be exaggerated for clarity. It will also be understood that when a layer or element is referred to as being "on" another layer or element, it can be directly on the other layer or element, or there may be intervening layers. Additionally, it will be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there may be one or more intervening layers. Like reference numerals refer to like elements throughout. As used herein, the term "or" is not necessarily exclusive; for example, "A or B" will include A, B, or A and B.

[0021] Unless explicitly described to the contrary, the words “comprise” and “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0022] Figure 1 shows a cross-sectional view of an electrode assembly according to an embodiment, and Figure 2 Show expanded Figure 1 electrode assembly.

[0023] like Figure 1 and Figure 2 As shown in , the electrode assembly 100 may include a stack 10 that may alternate positive electrodes, negative electrodes 20 , and a separator 30 .

[0024] The positive electrode 10 and the separator 30 may each have a sheet shape and may be stacked. The separator 30 may be on each side (eg, opposite sides) of the positive electrode 10 .

[0025] The positive electrode 10 may be made of or include a thin conductive metal plate, and for example, may include a substrate 2 serving as a current collector and a positive active material layer 3 , and the substrate 2 may be made of aluminum.

[0026] A compound for allowing reversible intercalation and deintercalation of lithium (eg, a lithiated intercalation compound) may be used as the positive active material forming the positive active material layer 3. In an embodiment, a composite oxide of a metal (eg, cobalt, manganese, nickel, or a combination thereof) and lithium may be used.

[0027] The content of the positive active material may be 90 wt % to 98 wt % based on the total weight of the positive active material layer.

[0028] The positive electrode active material layer 3 may further include a binder and a conductive material, and the binder and the conductive material may each be independently present in an amount of 1 wt % to 5 wt % based on the total weight of the positive electrode active material layer.

[0029] The binder can help attach the positive active material particles to each other and can help attach the positive active material to the substrate that is the current collector. In an embodiment, the binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, deacetylated cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin or nylon. The conductive material can provide conductivity to the electrode, and for the constructed battery, if the suitable material does not produce chemical changes and they can be electronically conductive materials, then they can be available.

[0030] The separator 30 may be a polymer film that allows lithium ions to pass through. In an embodiment, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used as the separator. In an embodiment, a mixed multilayer film such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used as the separator.

[0031] The separator 30 may be larger (e.g., in terms of area) than the positive electrode 10, and the edges of the paired separators 30 may be joined or merged to form a space for receiving or accommodating the positive electrode 10. The positive electrode 10 may be covered on or by the separator, except that the positive electrode tab may protrude from or outside the separator.

[0032] The negative electrode 20 may be strip-shaped and may be repeatedly bent in a direction covering the separator and the positive electrode. In an embodiment, the negative electrode 20 may be repeatedly bent in a first direction and a second direction to have a zigzag shape, with the first surfaces of the negative electrode 20 facing each other in the first direction and the second surfaces of the negative electrode 20 facing each other in the second direction.

[0033] The negative electrode 20 may include a substrate 5 and a negative active material layer 6 on the substrate 5. The substrate 5 of the negative electrode 20 may be repeatedly bent. The negative active material layer 6 (eg, once the electrode assembly is assembled) may overlap with the positive active material layer 3 of the positive electrode 10.

[0034] The substrate 5 of the negative electrode 20 may include a thin conductive metal plate and may serve as a current collector. In an embodiment, the substrate may be made of copper.

[0035] The negative electrode active material of the negative electrode active material layer 6 may include a carbon active material. The carbon negative electrode active material may include artificial graphite or a mixture of artificial graphite and natural graphite. In an embodiment, artificial graphite or a crystalline carbon material that is a mixture of artificial graphite and natural graphite may be used as the negative electrode active material, and compared with the use of amorphous carbon active material, the crystallization characteristics of the particles can be further developed, thereby further improving the arrangement characteristics of the carbon material in the pole plate in the external magnetic field, which is an advantage. The shape of artificial graphite or natural graphite may include an amorphous shape, a plate shape, a sheet shape, a spherical shape, a fibrous shape, a combination thereof, and any other suitable shape of any type. In an embodiment, artificial graphite and natural graphite may be mixed and used, and the weight mixing ratio thereof may be 70:30 to 95:5.

[0036] In an embodiment, the negative electrode active material layer may further include a silicon negative electrode active material, a tin negative electrode active material, or a LiMOx (M = metal) negative electrode active material. In an embodiment, the negative electrode active material layer may further include the above additional negative electrode active materials. For example, it may include a carbon negative electrode active material as the first negative electrode active material and a negative electrode active material as the second negative electrode active material, and the weight mixing ratio of the first negative electrode active material to the second negative electrode active material may be 50:50 to 99:1.

[0037] The LiMOx (M = metal) negative electrode active material may be a lithium vanadium oxide.

[0038] The Si negative electrode active material may include Si, Si-C composite materials, SiO x (0 < x ≤ 2, for example, SiO2) or Si-Q alloy (where Q is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, Group 15 element, Group 16 element, transition metal, rare earth element, or a combination thereof, and is not Si), and the Sn negative electrode active material may include Sn, SnO2, or Sn-R alloy (where R is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, Group 15 element, Group 16 element, transition metal, rare earth element, or a combination thereof, and is not Sn). In an embodiment, at least one of them and SiO2 may be mixed and used. The elements Q and R may include Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0039] Based on the total weight of the negative electrode active material layer 6, the content of the negative electrode active material on the negative electrode active material layer 6 may be 95 wt% to 99 wt%.

[0040] In an embodiment, the negative electrode active material may include a binder and may further include a conductive material. Based on the total weight of the negative electrode active material, the content of the binder in the negative electrode active material may be 1 wt% to 5 wt%. In an embodiment, a conductive material may be further included, and 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material may be used.

[0041] The binder may help attach the negative electrode active material particles to each other and may help attach the negative electrode active material to the negative electrode substrate. A non-aqueous binder, an aqueous binder, or a combination thereof may be used as the binder.

[0042] The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0043] The water-based adhesive may include styrene-butadiene rubber, acrylated styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, ethylene propylene polymer, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, acrylate resin or a combination thereof.

[0044] In an embodiment, an aqueous binder may be used as a negative electrode binder, and may further include a cellulose compound for providing viscosity as a thickener. In an embodiment, carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or an alkali metal salt thereof may be mixed and used as the cellulose compound. Na, K, or Li may be used as the alkali metal. The content of the thickener may be 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0045] The conductive material can provide conductivity to the electrode, and any type of suitable electronically conductive material that does not undergo chemical changes can be used to construct the battery. In embodiments, the conductive material can include: a carbon material including natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, or carbon fiber; a metal material such as metal powder or metal fiber including copper, nickel, aluminum, and silver; a conductive polymer including polyphenylene derivatives; or a conductive material including a mixture thereof.

[0046] The BET specific surface area of ​​the negative electrode active material layer can be less than 3.0 m 2 / g, for example 0.6m 2 / g to 1.2m 2 / g. The BET specific surface area of ​​the negative electrode active material layer is kept below 3.0 m 2 / g, as an advantage, the electrochemical life characteristics of the battery cell can be improved.

[0047] BET can be measured by charging and discharging a lithium rechargeable battery including a negative electrode, disassembling the fully discharged battery to obtain the negative electrode, cutting the negative electrode into a predetermined size, placing the cut negative electrode in a BET sample holder, and applying a nitrogen adsorption method thereto.

[0048] The negative electrode can have 6 mg / cm 2 Up to 65mg / cm2 Cross-sectional load level (L / L).

[0049] refer to Figure 1 In addition to the bent negative electrode 20 and the internal positive electrode 10, the electrode assembly 100 may further include a pair of external positive electrodes 11 respectively overlapping the bent negative electrode 20 or on the outermost surface of the bent negative electrode 20. The electrode assembly 100 may further include an external separator on each side of each external positive electrode 11 of the pair of external positive electrodes 11.

[0050] In an embodiment, an external positive electrode 11 may be further included, and the charge capacity of the electrode assembly may be improved by the added positive electrode. The negative active material layer may be on or at a surface of the negative electrode facing the external positive electrode 11.

[0051] The electrode assembly 100 may be received or housed in a pouch or can-shaped angular case together with an electrolyte and may be used as a rechargeable battery.

[0052] The electrolyte includes a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent can function as a medium through which ions involved in the electrochemical reaction of the battery move.

[0053] Lithium salts can be dissolved in organic solvents, which can serve as a source for supplying lithium ions in the battery to achieve the basic operation of the lithium secondary battery, and which can promote the movement of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts can include LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(CF3SO2)2N, LiN(SO3C2F5)2, LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(CxF 2x+1 SO2)(CyF 2y+1 SO2 (wherein x and y are natural numbers such as integers of 1 to 20), LiCl, LiI, and LiB(C2O4)2 (lithium bis(oxalato)borate: LiBOB).

[0054] The concentration of the lithium salt may be in the range of 0.1 M to 2.0 M. Including the lithium salt in the above concentration range may help ensure that the electrolyte may have excellent performance and lithium ion mobility due to optimal electrolyte conductivity and viscosity.

[0055] In an embodiment, the negative electrode may be formed by repeatedly bending, and thus the areas of the negative electrode and the positive electrode of the rechargeable battery may be increased, and the capacity of the rechargeable battery may be improved.

[0056] If the positive electrode is also to be repeatedly bent, the negative electrode active material layer can be formed on the bent portion of the positive electrode so that the positive electrode can face the negative electrode, and the negative electrode (larger than the positive electrode) can be bent, and if the positive electrode active material is not formed on the bent portion, there will be no change in capacity.

[0057] Figure 3 and Figure 4 A cross-sectional view of an electrode assembly according to another embodiment is shown.

[0058] Figure 3 and Figure 4 The electrode assembly shown in FIG is mostly similar to Figure 1 , and therefore the differences will now be described in detail.

[0059] like Figure 3 , an electrode assembly 101 according to another embodiment may include a stack 10 of positive electrodes, a pair of separators 30 on each side of the positive electrode 10, and a belt-type negative electrode 20 repeatedly bent around the positive electrode 10 and the separator 30. The outer positive electrode 11 and the separator 30 overlapping the outer positive electrode 11 may be on or at the outermost portion of the electrode assembly.

[0060] The negative electrode 20 may include a first negative electrode 21 and a second negative electrode 22 that overlap and are bent together. A first tape-type separator 31, a tape-type positive electrode 12, and a second tape-type separator 32 may be included between the first negative electrode 21 and the second negative electrode 22. The first tape-type separator 31, the tape-type positive electrode 12, and the second tape-type separator 32 may overlap the first negative electrode 21 and the second negative electrode 22. The first tape-type separator 31, the tape-type positive electrode 12, and the second tape-type separator 32 may be bent together with the first negative electrode 21 and the second negative electrode 22.

[0061] The strip-type positive electrode 12 may include a substrate and positive active material layers at regular intervals on the substrate of the strip-type positive electrode 12. The substrate of the strip-type positive electrode 12 (e.g., the substrate between the positive active material layers) may be repeatedly bent like the negative electrode 20, and the positive active material layers may be formed to have predetermined gaps therebetween.

[0062] If the positive electrode and the negative electrode are formed into a sheet shape and stacked, capacity loss may occur at the corners of the electrode assembly due to the size difference between the positive electrode and the negative electrode. However, in the embodiments or implementations of the present disclosure, the positive electrode active material and the negative electrode active material can be bent and attached to each other in the area where the strip-type positive electrode and the negative electrode are bent, and the bent portion can be used as capacity.

[0063] like Figure 4As shown in , an electrode assembly 102 according to another embodiment may include a stack 13 of positive electrodes repeatedly bent in a strip shape, a pair of separators 30 on each side of the positive electrode 13 , and a negative electrode 20 .

[0064] The positive electrodes 13 may each be bent once to cover or surround one bent portion of the negative electrode 20 on the side of the electrode assembly 102 and may have a V or U shape. The separator 30 may also be bent once together with the positive electrode 13 and may have a strip shape.

[0065] By summarizing and reviewing, the development of electric vehicles requires a high-capacity design with high energy density and fast charging characteristics to meet the characteristics of rechargeable batteries used in automobiles.

[0066] For high-capacity characteristics, the capacity may be increased by increasing the sizes of the positive and negative electrodes or increasing the number of positive and negative electrodes included in the electrode assembly.

[0067] One or more embodiments may provide an electrode assembly for maximizing the capacity of a rechargeable battery.

[0068] According to an embodiment, the negative electrode substrate may be formed by bending, and the positive electrode and the separator may be arranged and stacked between the bent negative electrodes, thereby maximizing the number of negative and positive electrodes included in the electrode assembly and improving the capacity of the rechargeable battery.

[0069] Thus far, example embodiments have been disclosed, and although specific terms are employed, they are used and should be interpreted only in a general, descriptive sense, and not for purposes of limitation. In some cases, as will be apparent to one of ordinary skill in the art at the time of filing this application, features, characteristics, and / or elements described in connection with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless specifically noted otherwise. Accordingly, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. An electrode assembly comprising: stacking of positive electrodes; a pair of separators on each side of each positive electrode in the stack of positive electrodes; as well as At least one negative electrode is in the form of a strip and is repeatedly bent around the stack of the separator and the positive electrode.

2. The electrode assembly according to claim 1, wherein The positive electrode and the separator each have a sheet shape.

3. The electrode assembly according to claim 1, wherein The at least one negative electrode is repeatedly bent in a first direction and a second direction, first surfaces of the at least one negative electrode face each other in the first direction, and second surfaces of the at least one negative electrode face each other in the second direction.

4. The electrode assembly according to claim 1, wherein: The at least one negative electrode includes a substrate and a negative active material layer on the substrate, and The substrate of the at least one negative electrode is repeatedly bent.

5. The electrode assembly according to claim 4, wherein: Each positive electrode in the stack of positive electrodes includes a first positive active material layer, and The negative electrode active material layer overlaps with the first positive electrode active material layer.

6. The electrode assembly according to claim 1, wherein Each separator in the pair of separators has an area larger than an area of ​​each positive electrode in the stack of positive electrodes.

7. The electrode assembly according to claim 6, wherein: The edges of the paired diaphragms are bonded to each other.

8. The electrode assembly according to claim 1, wherein: The at least one negative electrode includes a first negative electrode and a second negative electrode that overlap and bend each other, and The electrode assembly further includes a first belt-type separator, a belt-type positive electrode, and a second belt-type separator that are bent between the first negative electrode and the second negative electrode and together with the first negative electrode and the second negative electrode.

9. The electrode assembly according to claim 8, wherein: The strip-type positive electrode includes a substrate and a second positive active material layer on the substrate of the strip-type positive electrode at regular intervals, and The substrate of the strip-type positive electrode is bent between the second positive active material layers.

10. The electrode assembly according to claim 1, further comprising: a pair of external positive electrodes respectively overlapping outermost surfaces of the bent negative electrode; as well as An external separator on each side of each of the pair of external positive electrodes.

11. The electrode assembly according to claim 1, wherein Each positive electrode and each separator in the stack of positive electrodes surrounds one bent portion of the at least one negative electrode once on a side of the electrode assembly and covers the one bent portion of the at least one negative electrode.

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