KR20200090497A - The Electrode And The Electrode Assembly - Google Patents

Abstract

An electrode according to an embodiment of the present invention for solving the above problem includes: an active material coating unit coated with an electrode active material on at least one surface of an electrode current collector; and an active material uncoated unit on which the electrode active material is not coated and formed on one side of the active material coating unit. The active material uncoated unit comprises: a coating unit coated with a carbon coating material; and a lead connection unit on which the carbon coating material is not coated.

Description

Electrodes and electrode assemblies{The Electrode And The Electrode Assembly}

The present invention relates to an electrode and an electrode assembly, and more particularly, to an electrode and an electrode assembly capable of securing safety by suppressing initial heat generation even when the anode and the cathode are in direct contact.

In general, types of secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. These secondary batteries are not only small-sized products such as digital cameras, P-DVDs, MP3Ps, cell phones, PDAs, portable game devices, power tools, and e-bikes, but also large-sized products that require high output such as electric vehicles or hybrid vehicles and surplus power generation It is also applied to power storage devices that store power or renewable energy and power storage devices for backup.

In order to manufacture the electrode assembly, a cathode, a separator, and an anode are prepared and stacked. Specifically, a positive electrode active material slurry is applied to a positive electrode current collector, and a negative electrode active material slurry is applied to a negative electrode current collector to prepare a positive electrode and a negative electrode. In addition, when a separator is interposed and stacked between the prepared positive electrode and negative electrode, unit cells are formed, and unit cells are stacked to form an electrode assembly. And when the electrode assembly is accommodated in a specific case and the electrolyte is injected, a secondary battery is manufactured.

However, in the related art, when the secondary battery is operated abnormally, such as overcharging or overdischarging, the possibility that a short circuit (short) occurs due to the positive and negative electrodes directly contacting each other while the separator shrinks. As a result, the secondary battery exploded and a safety problem could occur.

Korea Publication No. 2012-0023491

The problem to be solved by the present invention is to provide an electrode and an electrode assembly capable of securing safety by suppressing initial heat generation even when the anode and the cathode are in direct contact.

The problems of the present invention are not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

An electrode according to an embodiment of the present invention for solving the above problems is an active material coating unit coated with an electrode active material on at least one surface of the electrode current collector; It is formed on one side of the active material coating unit, the electrode active material includes an uncoated active material uncoated portion, the active material uncoated portion, a coating portion coated with a carbon coating material; And a lead connection portion in which the carbon coating material is uncoated.

In addition, the electrode current collector may be a positive electrode current collector, and the electrode active material may be a positive electrode active material.

Further, the lead connection portion may have a length of at least 3 mm.

In addition, the carbon coating material may be coated on at least a portion of the active material application portion.

In addition, the carbon coating material may be coated on the entire surface of the active material application portion.

In addition, the electrode active material may be applied while covering the carbon coating material coated on the active material coating unit.

In addition, the carbon coating material may be coated while covering a part of the electrode active material.

In addition, the carbon coating material may include at least one of graphite, carbon black, carbon fiber, vapor-grown carbon fiber, carbon nanotube, and carbon nanofiber.

An electrode assembly according to an embodiment of the present invention for solving the above problems is formed on one side of the positive electrode active material coating unit, the positive electrode active material coating unit is coated with a positive electrode active material on at least one surface of the positive electrode current collector, the positive electrode active material is not A positive electrode including a coated positive electrode active material uncoated portion, the positive electrode active material uncoated portion comprising a carbon coating material coated coating portion and the carbon coating material uncoated lead connection portion; A negative electrode including a negative electrode active material coating part coated with a negative electrode active material on at least one surface of the negative electrode current collector, and a negative electrode active material uncoated part having the negative electrode active material uncoated; And a separator interposed between the positive electrode and the negative electrode.

The present invention also provides a secondary battery comprising the electrode assembly.

Other specific matters of the present invention are included in the detailed description and drawings.

According to embodiments of the present invention has at least the following effects.

Since the coating part coated with the carbon coating material on the uncoated portion of the active material at the positive electrode is included, even if the positive electrode and the negative electrode are in direct contact, initial heat generation is suppressed to ensure safety.

In addition, since the lead connecting portion in which the carbon coating material is not coated is included in the uncoated portion of the active material, it is possible to prevent the dust of the carbon coating material from scattering when connecting the leads.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is a schematic diagram of an electrode assembly according to an embodiment of the present invention.
2 is an assembly diagram of a pouch type secondary battery according to an embodiment of the present invention.
3 is a plan view of an anode according to an embodiment of the present invention.
4 is a partially enlarged view of a positive electrode active material coating part and a positive electrode active material uncoated part of a positive electrode according to an embodiment of the present invention.
5 is a plan view of a cathode according to an embodiment of the present invention.
6 is an enlarged view of a portion of a negative electrode active material coating portion and a negative electrode active material uncoated portion of a negative electrode according to an embodiment of the present invention.
7 is a partially enlarged view of a positive electrode active material coating part and a positive electrode active material uncoated part of a positive electrode according to another embodiment of the present invention.
8 is a partially enlarged view of a positive electrode active material coating part and a positive electrode active material uncoated part of a positive electrode according to another embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, and the present invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings commonly understood by those skilled in the art to which the present invention pertains. In addition, terms defined in the commonly used dictionary are not ideally or excessively interpreted unless specifically defined.

The terminology used herein is for describing the embodiments and is not intended to limit the present invention. In the present specification, the singular form also includes the plural form unless otherwise specified in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components other than the components mentioned.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of an electrode assembly 10 according to an embodiment of the present invention.

In the process of manufacturing the electrode assembly 10 according to an embodiment of the present invention, as described above, first, a slurry in which a positive electrode active material 1012 and a binder and a plasticizer are mixed is applied to the positive electrode current collector 1011, A slurry in which the negative electrode active material 1022 and a binder and a plasticizer are mixed is applied to the negative electrode current collector 1021 to prepare a positive electrode (Cathode 101) and a negative electrode (Anode, 102). And when the separator 101 is interposed and stacked between the prepared anode 101 and cathode 102, unit cells are formed, and the unit cells are stacked with each other, as shown in FIG. 1. Likewise, an electrode assembly 10 of a predetermined shape is formed.

The positive electrode 101 and the negative electrode 102 used in the present invention are not particularly limited as the positive electrodes 101 and 102, and the electrode active materials 1012 and 1022 are electrode current collectors according to conventional methods known in the art. 1011, 1021). Here, the positive electrode 101 may be prepared by applying a slurry of a positive electrode active material 1012, a conductive agent, and a binder on the positive electrode current collector 1011, followed by drying and pressing. At this time, if necessary, the slurry may further include a filler. The anode 101 may be manufactured in a sheet shape and mounted on a roll.

The positive electrode current collector 1011 is generally manufactured to a thickness of 3 to 500 μm. The positive electrode current collector 1011 is usually made of a material having high conductivity without causing chemical changes. For example, the material may be stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treatment of carbon, nickel, titanium, or silver on the surface of aluminum or stainless steel, but is not limited thereto. In addition, the positive electrode current collector 1011 may form fine irregularities on the surface to increase the adhesive force of the positive electrode active material 1012. In addition, the positive electrode current collector 1011 may be manufactured in various forms such as a film, sheet, foil, net, porous body, foam, and nonwoven fabric.

The positive electrode active material 1012 is a lithium secondary battery, for example, a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as the formula Li _{1 + x} Mn _{2 - x} O ₄ (x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ ,V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A nickel (Ni) site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x=0.01 to 0.3); Formula LiMn _{2 - x} M _x O ₂ (M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (M = Fe, Co, Ni, Cu or Zn Lithium manganese composite oxide represented by); LiMn ₂ O _{4 in} which part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) _{3 and the} like. However, it is not limited to these.

The conductive agent is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive electrode active material 1012. The conductive agent is usually made of a material that does not cause chemical changes and has conductivity. Examples of such materials include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, furnace black, channel black, lamp black, and thermal black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder is a component that assists in bonding the active material and the conductive agent and the like to the current collector, and is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture containing the positive electrode active material 1012. Such binders are typically polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene styrene rubber, fluorine rubber, various copolymers, and the like.

The filler is selectively used as a component that suppresses the expansion of the anode 101. And if it is a fibrous material without causing a chemical change, it can be generally used as a filler. Fillers include, for example, oliphine-based polymers such as polyethylene and polypropylene; It may be a fibrous material such as glass fiber, carbon fiber.

The negative electrode 102 may be manufactured, for example, by applying a negative electrode active material 1022 on the negative electrode current collector 1021 and then drying and pressing it. If necessary, a negative electrode active material 1022 may optionally include a conductive agent, a binder, and a filler. The cathode 102 may be manufactured in a sheet shape and mounted on a roll.

The negative electrode current collector 1021 is generally manufactured to a thickness of 3 to 500 μm. The negative electrode current collector 1021 is usually made of a material having conductivity without causing chemical changes. Copper, stainless steel, aluminum, nickel, titanium, calcined carbon, which are most typical of such materials, surface treatment of carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, or aluminum-cadmium alloy, etc. to be. In addition, the negative electrode current collector 1021 may also form fine irregularities on the surface to increase the bonding force of the negative electrode active material 1022. In addition, the negative electrode current collector 1021 may be manufactured in various forms such as a film, sheet, foil, net, porous body, foam, and nonwoven fabric.

The negative electrode active material 1022 may include, for example, carbon such as non-graphitized carbon and graphite-based carbon; Li _x Fe ₂ O ₃ (0=x=1), LixWO ₂ (0=x=1), Sn _x Me ₁ -xMe'yOz (Me: Mn, Fe, Pb, Ge; Me': Al, B, Metal complex oxides such as P, Si, and Group 1, Group 2, and Group 3 elements of the periodic table, halogen; 0<x=1;1=y=3;1=z=8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials.

As the separator that insulates the electrodes 101 and 102 between the anode 101 and the cathode 102, a commonly known polyolefin separator or a composite separator having an organic or inorganic composite layer formed on the olefin substrate can be used. It may, and is not particularly limited.

According to an embodiment of the present invention, the electrode assembly 10 having the above structure is accommodated in the battery case 13, and then the electrolyte is injected to manufacture the secondary battery 1.

2 is an assembly diagram of a pouch type secondary battery 1 according to an embodiment of the present invention.

The process of manufacturing the pouch type secondary battery 1 according to an embodiment of the present invention, as described above, after forming the electrode assembly 10, the electrode assembly 10 to the battery case 13 Insert and seal after injection of electrolyte.

Electrode assembly (Electrode Assembly, 10), as shown in Figure 1, includes an electrode tab (Electrode Tab, 11). The electrode tab 11 is respectively connected to the positive electrode 101 and the negative electrode 102 of the electrode assembly 10, and protrudes to the outside of the electrode assembly 10, so that electrons between the inside and outside of the electrode assembly 10 It becomes a path that can be moved. The electrode current collectors 1011 and 1021 of the electrode assembly 10 include the active material application parts 1013 and 1023 coated with the electrode active materials 1012 and 1022 and the active material uncoated portion 1014 without the electrode active materials 1012 and 1022 applied. , 1024), that is, it is composed of an uncoated portion. In addition, the electrode tab 11 may be formed by cutting the active material uncoated portions 1014 and 1024 or may be formed by connecting a separate conductive member to the active material uncoated portions 1014 and 1024 by ultrasonic welding or the like. 2, the electrode tabs 11 may protrude side by side in the same direction from one side of the electrode assembly 10, but are not limited thereto and may protrude in different directions.

An electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 by spot welding or the like. Then, a part of the electrode lead 12 is surrounded by the insulating portion 14. The insulating portion 14 is limited to the sealing portion 134 where the upper case 131 and the lower case 132 of the battery case 13 are heat-sealed, so that the electrode lead 12 is connected to the battery case 13. Bond. Then, the electricity generated from the electrode assembly 10 is prevented from flowing to the battery case 13 through the electrode lead 12, and the sealing of the battery case 13 is maintained. Therefore, the insulating portion 14 is made of a non-conductor having a non-conductivity that does not conduct electricity well. In general, as the insulating portion 14, it is easy to attach to the electrode lead 12 and uses a lot of relatively thin insulating tape, but is not limited thereto, and various members can be used if the electrode lead 12 can be insulated. have.

The electrode leads 12 may extend in the same direction to each other or may extend in opposite directions depending on the formation positions of the anode tab 111 and the cathode tab 112. The positive electrode lead 121 and the negative electrode lead 122 may have different materials from each other. That is, the positive electrode lead 121 is made of the same aluminum (Al) material as the positive electrode current collector 1011, and the negative electrode lead 122 is made of the same copper (Cu) material, nickel (Ni) material, or nickel as the negative electrode current collector 1021. It may be a copper (Cu) material coated with (Ni). In addition, a portion of the electrode lead 12 protruding to the outside of the battery case 13 becomes a terminal portion and is electrically connected to the external terminal.

In the pouch type secondary battery 1 according to the embodiments of the present invention, the battery case 13 is a pouch made of a flexible material. Hereinafter, the battery case 13 will be described as being a pouch. The battery case 13 accommodates and seals the electrode assembly 10 such that a portion of the electrode lead 12, that is, a terminal portion is exposed. 2, the battery case 13 includes an upper case 131 and a lower case 132. The lower case 132 is formed with a cup portion 133 in which an accommodation space 1331 for accommodating the electrode assembly 10 is provided, and in the upper case 131, the electrode assembly 10 is provided with a battery case 13. The receiving space 1331 is covered from the top so as not to escape to the outside. At this time, as illustrated in FIG. 2, the cup portion 133 in which the accommodation space 1331 is provided is also formed in the upper case 131 to accommodate the electrode assembly 10 from the top. The upper case 131 and the lower case 132 may be manufactured by being connected to one side as shown in FIG. 2, but are not limited thereto, and separately manufactured from each other.

When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10, and the insulating portion 14 is formed on a part of the electrode lead 12, the accommodation space 1331 provided in the lower case 132 In the electrode assembly 10 is accommodated, the upper case 131 covers the accommodation space 1331 from the top. Then, when the electrolyte is injected into the inside and the sealing portion 134 formed on the rim of the upper case 131 and the lower case 132 is sealed, the secondary battery 1 is manufactured.

3 is a plan view of the positive electrode 101 according to an embodiment of the present invention, Figure 4 is a positive electrode active material coating unit 1013 and the positive electrode active material uncoated portion 1014 of the positive electrode 101 according to an embodiment of the present invention Is an enlarged view of some.

According to an embodiment of the present invention, since the coating material 1016 coated with the carbon coating material 1015 is included in the active material uncoated parts 1014 and 1024 in the electrodes 101 and 102, the positive electrode 101 and the negative electrode 102 ) Even if it comes into direct contact, it is possible to secure safety by suppressing the initial heat generation. In addition, since the lead coating portion 1017 in which the carbon coating material 1015 is uncoated is included in the active material uncoated portions 1014 and 1024, it is possible to prevent the dust of the carbon coating material 1015 from being scattered when connecting the leads.

To this end, the electrodes 101 and 102 according to an embodiment of the present invention, the active material coating unit 1013, 1023, the electrode active material (1012, 1022) is applied to at least one surface of the electrode current collector (1011, 1021) ); It is formed on one side of the active material coating unit (1013, 1023), the electrode active material (1012, 1022) includes an uncoated active material uncoated portion (1014, 1024), the active material uncoated portion (1014, 1024), A coating portion 1016 coated with a carbon coating material 1015; And a lead connecting portion 1017 in which the carbon coating material 1015 is uncoated. In addition, the electrode current collectors 1011 and 1021 are positive electrode current collectors 1011, and the electrode active materials 1012 and 1022 may be positive electrode active materials 1012.

And the electrode assembly 10 according to an embodiment of the present invention is a positive electrode active material coating unit 1013, the positive electrode active material coating unit 1013, the positive electrode active material 1012 is applied to at least one surface of the positive electrode current collector 1011 ) Is formed on one side, the positive electrode active material 1012 includes an uncoated positive electrode active material uncoated portion 1014, and the positive electrode active material uncoated portion 1014 is a coating portion 1016 coated with a carbon coating material 1015 ) And the carbon coating material (1015) comprises an uncoated lead connection portion (1017), the positive electrode (101); It is formed on one side of the negative electrode active material coating unit 1023, the negative electrode active material coating unit 1023, the negative electrode active material 1022 is applied to at least one surface of the negative electrode current collector 1021, the negative electrode active material 1022 is not A negative electrode 102 including a coated negative active material uncoated portion 1024; And a separator interposed between the anode 101 and the cathode 102.

In the positive electrode 101 among the plurality of electrodes 101 and 102 included in the electrode assembly 10, the positive electrode active material applying unit 1013 is coated with a positive electrode active material 1012 on at least one surface of the positive electrode current collector 1011. Part. The positive electrode active material coating unit 1013 is a portion in which the positive electrode active material 1012 is coated on the positive electrode current collector 1011, as shown in FIG. 3, and as described above, the positive electrode active material 1012 is a conductive agent And a binder.

The positive electrode active material uncoated portion 1014 is formed on one side of the positive electrode active material coating portion 1013 in the positive electrode 101 and is a portion where the positive electrode active material 1012 is not applied. As described above, the positive electrode active material uncoated portion 1014 may be cut or a separate conductive member may be connected to form the positive electrode tab 111. Since the positive electrode active material uncoated portion 1014 is formed on one side of the positive electrode active material coating portion 1013, it is formed on the same surface of the positive electrode current collector 1011 as shown in FIG. 4.

While the secondary battery 1 is actually used, an accident may occur due to collision with the outside. For example, a sharp object may penetrate the secondary battery 1, and a short circuit may occur due to direct contact between the positive electrode 101 and the negative electrode 102. Such a short circuit can cause a large amount of gas generation, high temperature rise, and the like at a high speed in a short time, and further, a large explosion may occur, leading to a large accident. In general, when the positive electrode 101 and the negative electrode 102 are in contact, when the positive electrode current collector 1011 and the negative electrode current collector 1021 contact, when the positive electrode current collector 1011 and the negative electrode active material 1022 contact, There are four main cases, such as when the positive electrode active material 1012 and the negative electrode current collector 1021 contact, when the positive electrode active material 1012 and the negative electrode active material 1022 contact.

Among them, in general, when the positive electrode current collector 1011 and the negative electrode active material 1022 are in contact, the heat generation amount is the highest and the highest temperature is rapidly reached, so the risk of explosion is greatest. That is, the contact between the positive electrode current collector 1011 and the negative electrode active material 1022 is known as the most dangerous contact. Accordingly, according to an embodiment of the present invention, the positive electrode active material uncoated portion 1014 includes a coated portion 1016 coated with a carbon coating material 1015 and a lead connection portion 1017 coated with the carbon coating material 1015 uncoated. do.

The coating portion 1016 is a portion coated with the carbon coating material 1015 in the positive electrode active material uncoated portion 1014. The carbon coating material 1015 increases resistance, thereby reducing the amount of current flowing even when the positive electrode 101 and the negative electrode 102 are in contact, thereby preventing explosion and suppressing initial heat generation to secure safety. However, since the carbon coating material 1015 does not have insulating properties, electricity can be generated between the anode 101 and the cathode 102 through the coating portion 1016 coated with the carbon coating material 1015, By doing so, it is not possible to significantly reduce the energy density.

Therefore, in order for the coating portion 1016 to have conductivity, the carbon coating material 1015 includes graphite such as artificial graphite and natural graphite; Conductive carbon blacks such as acetylene black, ketjen black, furnace black, channel black, lamp black, and thermal black; Carbon fibers, vapor-grown carbon fibers, at least one of carbon nanotubes and carbon nanofibers may be included.

Meanwhile, as described above, the conductive material of the positive electrode active material 1012 may include materials such as graphite and carbon black. However, since this means that the conductive agent is mixed with the positive electrode active material 1012, various materials may be mixed in addition to the materials such as graphite and carbon black. On the other hand, it is preferable that most of the materials for the carbon coating material 1015 are materials such as graphite and carbon black. Thereby, safety and conductivity can be ensured together.

The carbon coating material 1015 is coated not only on the coating portion 1016, but also on at least a portion of the active material application portions 1013 and 1023. In particular, according to an embodiment of the present invention, the carbon coating material 1015 may be coated on the entire surface of the active material application parts 1013 and 1023. In addition, the electrode active materials 1012 and 1022 may be applied while covering the carbon coating material 1015 coated on the active material application parts 1013 and 1023.

In the positive electrode 101, as shown in FIG. 4, the carbon coating material 1015 is coated on at least a portion of the positive electrode active material coating unit 1013, and according to an embodiment of the present invention, the carbon coating material 1015 is coated with the positive electrode active material The entire surface of the portion 1013 may be coated. In addition, since the positive electrode active material coating unit 1013 needs to undergo ion exchange with the negative electrode 102 through the separation membrane, the carbon coating material 1015 is first coated on the positive electrode current collector 1011. In addition, it is preferable that the positive electrode active material 1012 is applied while covering the carbon coating material 1015 coated on the positive electrode active material applying unit 1013. Thus, the positive electrode active material coating unit 1013 may have a shape in which the positive electrode current collector 1011, the carbon coating material 1015, and the positive electrode active material 1012 are sequentially stacked. Therefore, even if the positive electrode 101 is penetrated by the material pointed at the positive electrode active material coating unit 1013, not the positive electrode active material uncoated portion 1014, and the positive electrode 101 and the negative electrode 102 contact each other, initial heat generation is suppressed. Safety.

The lead connecting portion 1017 is a portion in which the carbon coating material 1015 is uncoated in the positive electrode active material uncoated portion 1014. As described above, the positive electrode tab 111 may be formed by cutting the positive electrode active material uncoated portion 1014 or connecting a separate conductive member. In order to connect the positive electrode lead 121 to the positive electrode tab 111, various methods such as spot welding and laser welding may be used.

However, if the lead connecting portion 1017 does not exist, and the entire positive electrode active material uncoated portion 1014 is coated with a carbon coating material 1015 to become a coating portion 1016, the positive electrode tab 111 and the positive electrode lead 121 Part of the carbon coating material 1015 in the process of connecting to the dust may be scattered. By doing so, the dust may invade the manufacturing equipment of the secondary battery 1, and may have a negative effect such as shortening the life. However, according to an embodiment of the present invention, the positive electrode active material uncoated portion 1014 includes a carbon-coated material 1015, an uncoated lead connection portion 1017, so that when connecting the positive electrode lead 121, the carbon coating material 1015 Can prevent scattering of dust. If the length of the lead connecting portion 1017 is smaller than 3 mm, dust in the carbon coating material 1015 may still be scattered in the process of connecting the positive electrode lead 121, and the connection operation of the positive electrode lead 121 is not easy. not. However, if the length of the lead connecting portion 1017 is 3 mm or more, the dust of the carbon coating material 1015 is not scattered and the positive electrode lead 121 can be connected. Therefore, the lead connecting portion 1017 may have a length of at least 3 mm or more, and more preferably, may have a length of 5 mm or more in order to more easily connect the positive electrode lead 121.

5 is a plan view of the negative electrode 102 according to an embodiment of the present invention, Figure 6 is a negative electrode active material coating unit 1023 and the negative electrode active material uncoated portion 1024 of the negative electrode 102 according to an embodiment of the present invention Is an enlarged view of some.

According to an embodiment of the present invention, in the negative electrode 102 among the plurality of electrodes 101 and 102 included in the electrode assembly 10, the negative electrode active material coating unit 1023 is at least one surface of the negative electrode current collector 1021. It is the part to which the negative electrode active material 1022 was applied. As shown in FIG. 5, the negative electrode active material coating unit 1023 is a portion where the negative electrode active material 1022 is coated on the negative electrode current collector 1021, and as described above, the negative electrode active material 1022 is selectively applied to the negative electrode active material 1022. Conductive agents, binders, fillers, and the like.

The negative electrode active material uncoated portion 1024 is formed on one side of the negative electrode active material coating unit 1023 in the negative electrode 102 and is a portion where the negative electrode active material 1022 is uncoated. As described above, the negative electrode active material uncoated portion 1024 may be cut or a separate conductive member may be connected to form the negative electrode tab 112. Since the negative electrode active material uncoated portion 1024 is formed on one side of the negative electrode active material coating portion 1023, it is formed on the same surface of the negative electrode current collector 1021 as shown in FIG. 6.

As described above, since the risk of explosion is greatest when the positive electrode current collector 1011 and the negative electrode active material 1022 contact, the negative electrode current collector 1021 is attached to the positive electrode current collector 1011 or the positive electrode active material 1012. When in contact, the risk of explosion is relatively small. Therefore, according to an embodiment of the present invention, as shown in FIGS. 5 and 6, the cathode 102 may not be coated with a carbon coating material.

However, the present invention is not limited thereto, and the cathode 102 may also be coated with a carbon coating material. That is, when the negative electrode current collector 1021 is in contact with the positive electrode current collector 1011 or the positive electrode active material 1012, the risk of explosion is relatively small, but this is in contact with the positive electrode current collector 1011 and the negative electrode active material 1022. Compared to the case, it is only relative, and safety is not guaranteed. Therefore, the carbon coating material may be coated on the cathode 102. In this case, the negative electrode active material uncoated portion 1024 may also include a coated portion (not shown) coated with a carbon coating material and a lead connection portion (not shown) coated with the carbon coating material. In addition, in order to prevent a portion of the carbon coating material from being dusted and scattered in the process of connecting the negative electrode tab 112 and the negative electrode lead 122, the lead connection unit (not shown) may have a length of at least 3 mm or more, More preferably, it may have a length of 5 mm or more.

7 is a partially enlarged view of the positive electrode active material coating part 1013a and the positive electrode active material uncoated part 1014 of the positive electrode 101a according to another embodiment of the present invention.

As described above, the carbon coating material 1015 is coated not only on the coating portion 1016, but also on at least a portion of the positive electrode active material application portion 1013. In particular, according to an embodiment of the present invention, as illustrated in FIG. 4, the carbon coating material 1015 may be coated on the entire surface of the positive electrode active material application unit 1013. By doing so, even if the positive electrode 101 is penetrated by a sharp material in the positive electrode active material coating unit 1013, not the positive electrode active material uncoated portion 1014, the initial heat is generated even if the positive electrode 101 and the negative electrode 102 contact each other. It can be suppressed to ensure safety. However, this can increase the overall thickness of the electrode assembly 10.

Therefore, according to another embodiment of the present invention, the carbon coating material 1015a may be coated only on a part of one surface of the active material application parts 1013a and 1023 in the electrode current collectors 1011 and 1021. In addition, the electrode active materials 1012a and 1022 may be applied while covering the carbon coating material 1015a coated on the active material application parts 1013a and 1023.

In the positive electrode 101a, as illustrated in FIG. 7, the carbon coating material 1015a may be coated only on a part of one surface of the positive electrode active material application part 1013a. In addition, the positive electrode active material 1012a may be applied while covering the carbon coating material 1015a coated on the positive electrode active material application unit 1013a. By doing so, even if the positive electrode 101a and the negative electrode 102 are in direct contact with each other while the separator is contracted without increasing the overall thickness of the electrode assembly 10, it is possible to prevent explosion and suppress initial heat generation to secure safety. . In addition, since the positive electrode active material 1012a covers the carbon coating material 1015a, the carbon coating material 1015a can be easily prevented from being peeled off.

8 is a partially enlarged view of a positive electrode active material coating part 1013b and a positive electrode active material uncoated part 1014 of the positive electrode 101b according to another embodiment of the present invention.

According to one embodiment and another embodiment of the present invention, the carbon coating material 1015 is first coated on all or part of one surface of the coating part 1016 and the positive electrode active material applying part 1013 in the positive electrode current collector 1011. Then, the positive electrode active material 1012 is applied while covering the carbon coating material 1015 coated on the positive electrode active material coating unit 1013. However, in this case, the present invention cannot be applied to the existing positive electrode 101 in which the positive electrode active material 1012 is first applied to at least one surface of the positive electrode current collector 1011. That is, in order to apply the present invention, the existing anode 101 must be discarded and a new anode 101 must be manufactured. Then, there is a problem that the manufacturing time and cost of the secondary battery 1 are excessively wasted.

Therefore, according to another embodiment of the present invention, after the electrode active materials 1012b and 1022 are applied to the electrode current collectors 1011 and 1021, the carbon coating material 1015b covers a part of the electrode active materials 1012b and 1022, Is coated.

In the positive electrode 101b, as shown in FIG. 8, after the positive electrode active material 1012b is applied to the positive electrode current collector 1011, the carbon coating material 1015b is coated with a large portion of the positive electrode active material 1012b. By doing so, the present invention can be applied by coating the carbon coating material 1015b on the existing anode 101b without having to discard the existing anode 101b and prepare a new anode.

Those of ordinary skill in the art to which the present invention pertains will appreciate that the present invention may be implemented in other specific forms without changing its technical spirit or essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the following claims rather than the above detailed description, and various embodiments derived from the meaning and scope of the claims and their equivalent concepts should be interpreted to be included in the scope of the present invention.

1: secondary battery 10: electrode assembly
11: electrode tab 12: electrode lead
13: battery case 14: insulation
101: positive 102: negative
111: anode tab 112: cathode tab
121: positive lead 122: negative lead
131: upper pouch 132: lower pouch
133: cup portion 134: sealing portion
1011: positive electrode current collector 1012: positive electrode active material
1013: positive electrode active material coating portion 1014: positive electrode active material uncoated portion
1015: carbon coating material 1016: coating portion
1017: lead connection portion 1021: negative electrode current collector
1022: negative electrode active material 1023: negative electrode active material coating unit
1024: negative electrode active material uncoated portion 1331: accommodation space

Claims (10)

An active material coating unit having an electrode active material applied to at least one surface of the electrode current collector;
It is formed on one side of the active material coating unit, and includes an active material uncoated portion where the electrode active material is not applied,
The active material uncoated portion,
Carbon coating material coated coating portion; And
The carbon coating material comprises an uncoated lead connection, an electrode. According to claim 1,
The electrode current collector,
Anode current collector,
The electrode active material,
An electrode, which is a positive electrode active material. According to claim 1,
The lead connection portion,
An electrode having a length of at least 3 mm. According to claim 1,
The carbon coating material,
The electrode is also coated on at least a portion of the active material coating. According to claim 4,
The carbon coating material,
The electrode is coated on the entire surface of the active material coating unit. According to claim 4,
The electrode active material,
An electrode that is applied while covering the carbon coating material coated on the active material coating unit. According to claim 4,
The carbon coating material,
An electrode that is coated while covering a part of the electrode active material. According to claim 1,
The carbon coating material,
An electrode comprising at least one of graphite, carbon black, carbon fiber, vapor-grown carbon fiber, carbon nanotube, and carbon nanofiber. A positive electrode active material coating unit coated with a positive electrode active material on at least one surface of the positive electrode current collector, formed on one side of the positive electrode active material coating unit, includes a positive electrode active material uncoated portion where the positive electrode active material is uncoated, and the positive electrode active material uncoated portion , An anode comprising a coating portion coated with a carbon coating material and a lead connection portion without coating the carbon coating material;
A negative electrode including a negative electrode active material coating unit coated with a negative electrode active material on at least one surface of the negative electrode current collector, and a negative electrode active material non-coating unit formed on one side of the negative electrode active material coating unit; And
An electrode assembly including a separator interposed between the anode and the cathode. A secondary battery comprising the electrode assembly according to claim 9.

Images