Electrode assembly including a negative electrode with an extension

Abstract

The present invention relates to an electrode assembly including a negative electrode having an extension, the electrode assembly including a positive electrode having a positive electrode tab protruding from an outer circumferential edge on one side and a positive electrode active material coated on the positive electrode current collector, a negative electrode having a negative electrode tab protruding from an outer circumferential edge on one side and a negative electrode active material coated on the negative electrode current collector, and a separator located between the positive electrode and the negative electrode, the negative electrode having an extension extending a predetermined length from an edge, and the separator having a bent portion bent at a predetermined angle to surround a portion of a side surface of the positive electrode at an edge.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0000873, filed January 4, 2022, and Korean Patent Application No. 10-2022-0182022, filed December 22, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly including a negative electrode with an extension, and more particularly to an electrode assembly including a negative electrode with an extension that can prevent positive and negative electrodes of the electrode assembly from moving out of their aligned positions due to external impact and vibration. [Background technology]

[0003] Recently, the demand for secondary batteries that can store electrical energy produced by the development of alternative energy sources due to air pollution caused by the use of fossil fuels and energy depletion has increased. Rechargeable secondary batteries are used in mobile devices, electric vehicles, hybrid electric vehicles, etc., and are closely related to daily life.

[0004] Secondary batteries are used as energy sources for various electronic devices that are essential in modern society, and the required capacity is increasing due to the increasing use and complexity of mobile devices and the development of electric vehicles, etc. To meet user demands, small devices are equipped with multiple battery cells, while automobiles and other devices use battery modules that electrically connect multiple battery cells or battery packs that include multiple such battery modules.

[0005] The lithium ion battery installed in a hybrid vehicle is subjected to shocks, vibrations, and other external factors due to the movement of the vehicle, and these external factors are transmitted to the battery.

[0006] An electrode assembly is formed by stacking flat electrodes and separators. When the electrode assembly is installed in a device such as a vehicle, the stacking arrangement may be irregularly changed due to external impact, vibration, and shaking. This positional change may cause the positive and negative electrodes to come into contact with each other, resulting in a short circuit. In addition, the vertical and horizontal positions of the positive and negative electrodes may change, resulting in an electrode overhang reversal phenomenon, which may cause lithium deposition problems.

[0007] A cross-sectional view of a conventional electrode assembly is shown in Fig. 1. As shown in Fig. 1, the conventional electrode assembly is formed by stacking a flat plate-shaped positive electrode 10, a separator 20 made of an insulating material, and a flat plate-shaped negative electrode 30 in that order, and by closely contacting multiple such unit cells.

[0008] As shown in FIG. 1, in the conventional electrode assembly, the positive electrode 10, the separator 20, and the negative electrode 30 are flat, and there is a problem in that the alignment may become misaligned due to external impact, shaking, vibration, etc., causing the positive electrode 10 and the negative electrode 30 to come into contact with each other, resulting in a short circuit.

[0009] In addition, the alignment position of the positive electrode 10 and the negative electrode 30 is misaligned, and an electrode overhang reversal phenomenon occurs at positions where the amount of negative electrode active material located on the vertical line and the horizontal line is reduced, which may cause lithium deposition, resulting in a shortened battery life, performance degradation, and battery failure. This phenomenon may also cause secondary damage such as fire. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 10-2019-0065147 Summary of the Invention [Problem to be solved by the invention]

[0011] In order to solve the above problems, an object of the present invention is to provide an electrode assembly including a negative electrode with an extension that can fix the positions of the positive electrode and the negative electrode to prevent short circuits caused by contact between the positive electrode and the negative electrode.

[0012] Another object of the present invention is to provide an electrode assembly including a negative electrode having an extension portion that can prevent the occurrence of an electrode overhang inversion phenomenon by preventing the positive and negative electrodes from being misaligned vertically and horizontally. [Means for solving the problem]

[0013] To achieve the above object, the electrode assembly including the anode with an extension according to the present invention includes a cathode (100) having a cathode tab (110) protruding from one outer periphery and a cathode active material (120) coated on a cathode current collector (130), a cathode (200) having a cathode tab (210) protruding from one outer periphery and a cathode active material (220) coated on a cathode current collector (230), and a separator (300) positioned between the cathode and the anode, wherein the anode (200) has an extension (240) extending a predetermined length from an edge thereof, and the separator (300) has a bent portion (310) bent at a predetermined angle at an edge thereof to surround a portion of a side surface of the cathode (100).

[0014] In the electrode assembly of the present invention, the extensions (240) are formed on the edges of both sides of the negative electrode (200).

[0015] In the electrode assembly of the present invention, the extensions (240) are formed at the edges of both side surfaces, the front surface and the rear surface of the negative electrode (200).

[0016] In the electrode assembly of the present invention, the extension (240) is formed at a part of the edge of the negative electrode (200).

[0017] In the electrode assembly of the present invention, the lower end of the extension (240) has an uneven shape.

[0018] In the electrode assembly of the present invention, the lower end of the extension (240) is characterized by having a wave shape.

[0019] The present invention may also be a battery cell including the electrode assembly described above.

[0020] The present invention may also be a battery module that houses the above-described battery cells. [Effects of the Invention]

[0021] As described above, the electrode assembly including the negative electrode with an extension according to the present invention has an extension extending perpendicularly to the edge of the negative electrode, and the extension surrounds the side of the positive electrode, thereby preventing misalignment of the negative and positive electrodes and suppressing the occurrence of short circuits due to contact.

[0022] In addition, according to the electrode assembly including the negative electrode with the extension part according to the present invention, by providing the extension part on the side of the negative electrode, the amount of negative electrode active material at the position where the positive electrode and the negative electrode face each other can be increased, which has the advantage of preventing an electrode overhang inversion.

[0023] In addition, according to the electrode assembly including the negative electrode with the extension portion according to the present invention, the negative electrode capacity is increased by the extension portion of the negative electrode, and the ratio of the negative electrode capacity to the positive electrode capacity is increased, thereby reducing the possibility of precipitation. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a cross-sectional view showing an electrode assembly according to the prior art. [Figure 2] 1 is a perspective view showing an electrode assembly according to a first preferred embodiment of the present invention; [Figure 3] FIG. 3 is a cross-sectional view taken along line AA' in FIG. 2. [Figure 4] FIG. 4 is a perspective view showing an electrode assembly according to a second preferred embodiment of the present invention. [Figure 5] FIG. 10 is a perspective view showing an electrode assembly according to a third preferred embodiment of the present invention. [Figure 6] FIG. 10 is a perspective view showing an electrode assembly according to a fourth preferred embodiment of the present invention. [Figure 7] FIG. 10 is a perspective view showing an electrode assembly according to a fifth preferred embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view taken along line AA' in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, with reference to the accompanying drawings, a detailed description will be given of an embodiment of the present invention that will enable a person skilled in the art to easily carry out the present invention. However, in describing the operation principle of the preferred embodiment of the present invention in detail, detailed description of related well-known functions or configurations will be omitted if it is determined that such detailed description may unnecessarily obscure the gist of the present invention.

[0026] Furthermore, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only a direct connection but also an indirect connection via another element therebetween. Furthermore, unless otherwise specified, "including a certain element" does not mean that other elements are excluded, but that other elements may also be included.

[0027] Hereinafter, an electrode assembly including a negative electrode with an extension according to the present invention will be described with reference to the accompanying drawings.

[0028] FIG. 2 is a perspective view showing an electrode assembly according to a first preferred embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line AA' of FIG.

[0029] Referring to FIGS. 2 and 3, an electrode assembly according to a preferred embodiment of the present invention includes a positive electrode 100, a negative electrode 200, and a separator 300 interposed between the positive electrode 100 and the negative electrode 200.

[0030] The positive electrode 100 has a positive electrode tab 110 protruding from one outer peripheral edge by a predetermined length, and a positive electrode active material 120 coated on a positive electrode current collector 130 .

[0031] For example, although the corners of the positive electrode active material 120 applied to the positive electrode current collector 130 are shown as being right-angled in the drawings, the corners of the positive electrode active material 120 may have a sliding shape with a predetermined curvature or an inclined surface shape inclined at a predetermined angle.

[0032] The positive electrode active material 120 may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x Lithium manganese oxides such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); 2-x M x Lithium manganese composite oxides expressed as Li2Mn3MO8 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1); LiMn2O4, in which part of the Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, LiNi x Mn 2-x O4(0.01≦x≦0.6) can be used.

[0033] Meanwhile, the positive electrode active material 120 may be mixed with a conductive material and a binder, and a filler may be further added, if necessary.

[0034] The conductive material is typically added in an amount of 1 to 50 wt % based on the total weight of the mixture including the positive electrode active material 120. Such a conductive material is not particularly limited as long as it is conductive without causing any chemical changes in the battery, and examples that can be used include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0035] The binder is a component that helps bind the positive electrode active material 120 to the conductive material and to the current collector, and is typically added in an amount of 1 to 50 wt % based on the total weight of the mixture including the positive electrode active material 120. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butylene rubber, fluororubber, and various copolymers.

[0036] The positive electrode current collector 130 can generally have a thickness of 3 to 500 μm. It is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those with surface treatment such as carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel can be used. Also, in order to enhance the adhesive force of the positive electrode active material, it is possible to form fine irregularities on the surface, or various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven bodies, etc. are possible.

[0037] Next, in the negative electrode 200, the negative electrode tab 210 protrudes from one side of the outer peripheral end by a predetermined length, the negative electrode active material 220 is coated on the negative electrode current collector 230, and an extension portion 240 extending in the vertical direction by a predetermined length is provided at the edge of the negative electrode 200.

[0038] For example, in the drawing, the corner of the negative electrode active material 220 coated on the negative electrode current collector 230 is shown as a right-angled shape, but the corner of the negative electrode active material 220 can have a slide shape with a predetermined curvature or the shape of an inclined surface inclined at a predetermined angle.

[0039] The negative electrode active material 220 is, for example, LixFe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8), etc. metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0040] The negative electrode current collector 230 is generally manufactured to have a thickness of 3 to 500 μm. The negative electrode current collector 230 is not particularly limited as long as it is conductive and does not cause chemical changes in the battery. Examples of the negative electrode current collector 230 include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys. Similarly to the positive electrode current collector 130, the surface may be formed with fine irregularities to strengthen the binding strength of the negative electrode active material. Various forms, such as a film, sheet, foil, net, porous material, foam, and nonwoven fabric, may be used.

[0041] Here, the electrode assembly may be a unidirectional electrode assembly in which a positive electrode tab 110 and a negative electrode tab 210 are formed on one side, or a bidirectional electrode assembly in which a positive electrode tab 110 is formed on one side and a negative electrode tab 210 is formed on the other side.

[0042] The extensions 240 extend vertically from both side edges of the negative electrode 200 by a predetermined length and are positioned to surround the side surfaces of the positive electrode 100, which has the advantage of preventing the positive electrode 100 and the negative electrode 200 from shifting in position due to vibration caused by external impact.

[0043] In addition, the provision of the extension 240 has the advantage of suppressing an electrode overhang inversion phenomenon that may occur when the positive electrode 100 and the negative electrode 200 are misaligned due to external impact, vibration, or shaking, thereby preventing lithium deposition, thereby improving safety.

[0044] For example, although the drawing shows the extension 240 as surrounding the side of the positive electrode 100, if the separator 300 extends further to surround the positive electrode 100, the negative electrode 200 may surround the entire positive electrode 100.

[0045] Next, the separator 300 has bent portions 310 formed at both edges thereof at a predetermined angle, which advantageously prevents contact between the extension portion 240 and the side of the positive electrode 100, thereby preventing the occurrence of a short circuit.

[0046] Here, the predetermined angle of the separator 300 is an angle at which the separator 300 is bent so as to come into close contact with the side surface of the positive electrode 100. For example, if the angle between the top surface and the side surface of the positive electrode 100 is 90°, the separator 300 may be similarly bent at 90° so as to come into close contact with the side surface of the positive electrode 100.

[0047] In addition, the separator 300 is located between the upper surface of the positive electrode 100 and the lower surface of the negative electrode 200, thereby preventing short circuits and allowing only the movement of lithium ions. The separator 300 is preferably made of any one material selected from the group consisting of polyethylene, polypropylene, a polyethylene / polypropylene double layer, a polyethylene / polypropylene / polyethylene triple layer, a polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper, but is not limited thereto.

[0048] FIG. 4 is a perspective view showing an electrode assembly according to a second preferred embodiment of the present invention.

[0049] Referring to FIG. 4, the electrode assembly according to the second embodiment of the present invention is similar to the electrode assembly according to the first embodiment described with reference to FIGS. 2 and 3 except for the shape of the extension 240 of the negative electrode 200 and the shape of the separator 300, and therefore, a description of the same components will be omitted.

[0050] In the electrode assembly according to the second embodiment of the present invention, the extensions 240 of the negative electrode 200 extend vertically from the edges of the front and rear surfaces of the negative electrode 200 by a predetermined length and surround the front and rear sides of the positive electrode 100. This prevents the positive electrode 100 and the negative electrode 200 from shifting in the front-rear direction, thereby providing an advantage of improved safety.

[0051] In addition, the separator 300 has bent portions 310 formed by bending the edges of the front and rear surfaces at a predetermined angle, thereby preventing the front and rear surfaces of the positive electrode 100 from contacting the extension portion 240.

[0052] FIG. 5 is a perspective view showing an electrode assembly according to a third preferred embodiment of the present invention.

[0053] Referring to FIG. 5, the electrode assembly according to the third embodiment of the present invention is similar to the electrode assembly according to the first embodiment described with reference to FIGS. 2 and 3, except for the shape of the extension 240 of the negative electrode 200 and the shape of the separator 300. Therefore, a description of the same components will be omitted.

[0054] In the electrode assembly according to the third embodiment of the present invention, the extensions 240 of the negative electrode 200 extend vertically by a predetermined length from both sides, front, and rear of the negative electrode 200, surrounding both sides, front, and rear of the positive electrode 100. This prevents the positive electrode 100 and the negative electrode 200 from shifting in the left-right and front-rear directions, thereby providing an advantage of improved safety.

[0055] In addition, the separator 300 has bent portions 310 formed at both sides, front and rear ends at a predetermined angle, thereby preventing the side of the positive electrode 100 from contacting the extension portion 240 .

[0056] FIG. 6 is a perspective view showing an electrode assembly according to a fourth preferred embodiment of the present invention.

[0057] Referring to FIG. 6, the electrode assembly according to the fourth preferred embodiment of the present invention is similar to the electrode assembly according to the first embodiment described with reference to FIGS. 2 and 3, except for the shape of the extension 240 and the shape of the separator 300, and therefore, a description of the same components will be omitted.

[0058] In the electrode assembly according to the fourth preferred embodiment of the present invention, the extension 240 of the negative electrode 200 may have a shape in which it extends vertically by a predetermined length only at a portion of the edge of the negative electrode 200 .

[0059] For example, the lower end 241 of the extension 240 may have an uneven shape as shown in FIG. 6 and surround only a portion of the positive electrode 100, thereby advantageously preventing misalignment between the positive electrode 100 and the negative electrode 200 due to external impact and reducing manufacturing costs.

[0060] In addition, the shape of the lower end 241 may be wavy, and is not limited to this as long as it surrounds part of the side surface of the positive electrode 100, thereby fixing the positive electrode 100 and the negative electrode 200 together, and can reduce manufacturing costs.

[0061] FIG. 7 is a perspective view showing an electrode assembly according to a fifth preferred embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along line AA' of FIG.

[0062] Referring to Figures 7 and 8, the electrode assembly according to the fifth preferred embodiment of the present invention is similar to the electrode assembly according to the first embodiment described in Figures 2 and 3 except for the shape of the extension portion 240, so a description of the same configuration will be omitted.

[0063] In the electrode assembly according to the fifth preferred embodiment of the present invention, the extension 240 of the negative electrode 200 may have a shape that extends in a direction parallel to the negative electrode 200 .

[0064] Since the extension 240 does not extend in the lateral direction of the positive electrode 100, the volume of the negative electrode 200 is smaller than that of the first embodiment, thereby reducing manufacturing costs.

[0065] The present invention may be a battery cell including the electrode assembly described above, a battery module housing the battery cell, or a device equipped with the battery module. For example, the device may be an electronic device including a large-capacity battery, such as an electric vehicle, a hybrid vehicle, or a plug-in hybrid electric vehicle.

[0066] In addition, the electrode assembly described above in the present invention may be applied to stack-type battery cells such as pouch-type battery cells and prismatic battery cells, and may also be applied to winding-type battery cells in which the electrode assembly is wound, such as cylindrical battery cells.

[0067] Although specific portions of the contents of the present invention have been described in detail above, it will be apparent to those skilled in the art that such specific techniques are merely preferred embodiments and do not limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of the present invention, and it goes without saying that such changes and modifications also fall within the scope of the accompanying claims. [Explanation of symbols]

[0068] 100 positive electrode 110 Positive electrode tab 120 Cathode active material 130 Positive electrode current collector 200 negative electrode 210 Negative electrode tab 220 Anode active material 230 Negative electrode current collector 240 Extension 241 Lower end 300 Separation membrane 310 Bend section

Claims

1. a positive electrode having a positive electrode tab protruding from one outer peripheral end and a positive electrode active material coated on a positive electrode current collector; a negative electrode having a negative electrode tab protruding from one outer peripheral end and a negative electrode active material coated on a negative electrode current collector; a separator located between the positive electrode and the negative electrode, The negative electrode has an extension extending from an edge thereof by a predetermined length, a bent portion bent at a predetermined angle at an edge of the separation membrane so as to surround a part of a side surface of the positive electrode, The lower end of the extension has an uneven shape. Flat plate electrode assembly.

2. The electrode assembly according to claim 1 , wherein the extension portion is bent and extends vertically from an edge of the negative electrode so as to surround a side surface of the positive electrode.

3. The electrode assembly according to claim 2 , wherein the extensions are formed on the edges of both sides of the negative electrode.

4. The electrode assembly according to claim 2 , wherein the extensions are formed on the side of the edge of the negative electrode from which the positive electrode tab or the negative electrode tab protrudes and on the opposite side.

5. The electrode assembly according to claim 2 , wherein the extensions are formed on both side surfaces of the negative electrode, and on the side of the edge of the negative electrode from which the positive electrode tab or the negative electrode tab protrudes and on the opposite side.

6. The electrode assembly according to claim 2 , wherein the extension is formed on a part of an edge of the negative electrode.

7. The electrode assembly of claim 6 , wherein the lower end of the extension has a corrugated shape.

8. A battery cell comprising the electrode assembly according to any one of claims 1 to 7.

9. A battery module containing the battery cell according to claim 8.

Images