This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0007597 dated January 21, 2019, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification.
[3]
technical field
[4]
The present invention relates to an electrode and an electrode assembly, and more particularly, an electrode and an electrode assembly capable of securing safety by suppressing initial heat generation through an endothermic reaction of a flame retardant during abnormal operation such as an internal short circuit, an external short circuit, overcharge, and overdischarge is about
background
[5]
In general, types of secondary batteries include a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, and a lithium ion polymer battery. These secondary batteries are not only used in small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, Portable Game Devices, Power Tools and E-bikes, but also in large products requiring high output such as electric and hybrid vehicles and surplus power generation. It is also applied and used in power storage devices that store power or renewable energy and power storage devices for backup.
[6]
In order to manufacture the electrode assembly, a cathode, a separator, and a cathode are manufactured, and these are laminated. 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. And when a separator is interposed between the manufactured positive electrode and the negative electrode and stacked, unit cells are formed, and the unit cells are stacked on each other, thereby forming an electrode assembly. And when the electrode assembly is accommodated in a specific case and an electrolyte is injected, a secondary battery is manufactured.
[7]
However, in the related art, when a secondary battery is exposed to high temperature or operates abnormally, such as an internal/external short circuit, overcharging or overdischarging, the separator contracts due to heat generation and the positive and negative electrodes directly contact each other, resulting in a short circuit. more likely to occur In addition, a short circuit may occur due to the contact between the positive and negative electrodes due to defects during battery production. Due to such a short circuit, rapid electron movement occurs inside the battery, and as a result, when heat and side reactions occur, the secondary battery may explode, resulting in a safety problem. In particular, when an electrical malfunction such as overcharge, overdischarge, or external short circuit occurs, a high current flows and the heat conductivity of the current collector is low, so that the temperature of the current collector is higher than that of the active material layer. After that, heat was diffused and thermal, chemical, and electrochemical reactions of components such as active materials and electrolytes were added, leading to thermal runaway.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[8]
The problem to be solved by the present invention is to prevent the short circuit between the positive electrode and the negative electrode during abnormal operation such as short circuit or internal short circuit, external short circuit, overcharge, and overdischarge, which may occur during battery manufacturing, and at the same time prevent short circuit between the positive electrode and the negative electrode and absorb heat of the flame retardant To provide an electrode and an electrode assembly capable of securing safety by suppressing initial heat generation through a reaction.
[9]
The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.
means of solving the problem
[10]
An electrode according to an embodiment of the present invention for solving the above problems includes an active material application unit coated with an electrode active material on at least one surface of an electrode current collector; an active material uncoated portion formed on one side of the active material applying portion, to which the electrode active material is not applied; and a coating part coated between the active material application part and the active material uncoated part and including a flame retardant.
[11]
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.
[12]
In addition, the flame retardant may include a halogen-based flame retardant, a phosphorus-based flame retardant, or an inorganic compound flame retardant.
[13]
In addition, the flame retardant may include Al(OH) 3 , Mg(OH) 2 , or BH 3 O 3 .
[14]
In addition, the coating part may be coated including an interface between the active material application part and the active material uncoated part.
[15]
In addition, the active material application part and the active material uncoated part may be formed on the same surface of the electrode current collector.
[16]
An electrode assembly according to an embodiment of the present invention for solving the above problems is formed on at least one surface of a positive electrode current collector with a positive electrode active material coating portion coated with a positive electrode active material, one side of the positive electrode active material application portion, and the positive electrode active material is not coated a positive electrode comprising a non-coated positive electrode active material portion and a positive electrode coating portion coated between the positive electrode active material application portion and the positive electrode active material uncoated portion and including a flame retardant; a negative electrode comprising a negative active material coating unit coated with a negative active material on at least one surface of a negative electrode current collector, and a negative electrode active material uncoated portion formed on one side of the negative active material application unit, to which the negative active material is not applied; and a separator interposed between the anode and the cathode.
[17]
In addition, the negative electrode may further include a negative electrode coating portion coated between the negative electrode active material application portion and the negative electrode active material uncoated portion and including a flame retardant.
[18]
The present invention also provides a secondary battery including the electrode assembly.
[19]
In addition, the secondary battery may include a plurality of electrode tabs each protruding from the positive electrode and the negative electrode to one side; a plurality of electrode leads respectively connected to the electrode tabs to transmit electricity generated inside the electrode assembly to the outside; a battery case accommodating the electrode assembly therein; and an insulating part that surrounds the electrode lead, is sealed together with the battery case, and includes a flame retardant.
[20]
Other specific details of the invention are included in the detailed description and drawings.
Effects of the Invention
[21]
According to the embodiments of the present invention, there are at least the following effects.
[22]
Between the active material coated part and the non-active material coated part of the electrode, the non-conductive and flame retardant coating part is coated. can
[23]
In addition, during non-ideal operation of the battery, the flame retardant suppresses the initial heat generation, thereby ensuring safety.
[24]
The effect according to the present invention is not limited by the contents exemplified above, and more various effects are included in the present specification.
Brief description of the drawing
[25]
1 is a schematic diagram of an electrode assembly according to an embodiment of the present invention.
[26]
2 is an assembly view of a pouch-type secondary battery according to an embodiment of the present invention.
[27]
3 is a plan view of an anode according to an embodiment of the present invention.
[28]
4 is an enlarged view of a portion of the positive electrode active material coated portion and the positive electrode active material uncoated portion of the positive electrode according to an embodiment of the present invention.
[29]
5 is a plan view of a cathode according to an embodiment of the present invention.
[30]
6 is an enlarged view of a portion of the anode active material coated portion and the anode active material uncoated portion of the anode according to an embodiment of the present invention.
[31]
7 is a plan view of a cathode according to another embodiment of the present invention.
[32]
8 is an enlarged view of a portion of an anode active material coated portion and an anode active material uncoated portion of the anode according to another embodiment of the present invention.
Modes for carrying out the invention
[33]
Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction 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 those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.
[34]
Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless clearly specifically defined.
[35]
The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components.
[36]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[37]
1 is a schematic diagram of an electrode assembly 10 according to an embodiment of the present invention.
[38]
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 the positive electrode active material 1012, a binder, and a plasticizer are mixed is applied to the positive electrode current collector 1011, A slurry in which the negative active material 1022, 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 a separator 103 is interposed between the prepared positive electrode 101 and the negative electrode 102 and stacked, unit cells are formed, and the unit cells are stacked on each other, so that as shown in FIG. Similarly, the electrode assembly 10 having a predetermined shape is formed.
[39]
The positive electrodes 101 and 102 of the positive electrode 101 and the negative electrode 102 used in the present invention are not particularly limited, and the electrode active materials 1012 and 1022 are applied to the electrode current collector ( 1011, 1021) may be prepared in the form of binding. Here, the positive electrode 101 may be manufactured, for example, by applying a slurry of the positive electrode active material 1012 , a conductive agent and a binder on the positive electrode current collector 1011 , drying and pressing the slurry. At this time, if necessary, the slurry may further include a filler. The positive electrode 101 may be manufactured in a sheet shape and mounted on a roll.
[40]
The positive electrode current collector 1011 is generally manufactured to have 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 change. Such a material may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treatment of carbon, nickel, titanium, silver, etc. 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 in order 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, a sheet, a foil, a net, a porous body, a foam, a nonwoven body, and the like.
[41]
In the case of a lithium secondary battery, the positive active material 1012 may include, for example, a layered compound such as lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), or a compound substituted with one or more transition metals; Lithium manganese oxide such as 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 ); LiV 3 O 8 , LiFe 3 O 4 ,V 2 O 5 , Cu 2 V 2 O vanadium oxide such as 7 ; 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, 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) ) represented by lithium manganese composite oxide; ternary lithium oxides such as the formula Li[Ni 1-xy Co x M y ]O 2 (M = Mn or Al, and x, y = 0 to 1); Formula Li[Ni 1-xy Co x Mn yquaternary lithium oxides such as Al z ]O 2 (x, y, z = 0 to 1); LiMn 2 O 4 in which a part of Li in the formula is substituted with an alkaline earth metal ion ; disulfide compounds; Fe 2 (MoO 4 ) 3 and the like. However, it is not limited only to these.
[42]
The conductive agent is typically added in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive active material 1012 . The conductive agent is usually made of a material having conductivity without causing a chemical change. As such a material, For example, 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 summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; A conductive material such as a polyphenylene derivative may be used.
[43]
The binder is a component that assists in bonding between the active material and the conductive agent and bonding to the current collector, and is typically added in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive active material 1012 . Such binder is typically polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , polypropylene, ethylene-propylene-diene ter polymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluororubber, various copolymers, and the like.
[44]
The filler is optionally used as a component for suppressing the expansion of the positive electrode 101 . And if it is a fibrous material without causing a chemical change, it can generally be used as a filler. The filler may be, for example, an olipine-based polymer such as polyethylene or polypropylene; It may be a fibrous material such as glass fiber or carbon fiber.
[45]
The negative electrode 102 may be manufactured, for example, by coating the negative electrode active material 1022 on the negative electrode current collector 1021 , then drying and pressing the negative electrode active material 1022 . If necessary, the negative active material 1022 may optionally include a conductive agent, a binder, a filler, and the like. The negative electrode 102 may be manufactured in a sheet shape and mounted on a roll.
[46]
The negative electrode current collector 1021 is generally manufactured to have a thickness of 3 to 500 μm. The negative electrode current collector 1021 is usually made of a material having conductivity without causing chemical change. Copper, stainless steel, aluminum, nickel, titanium, calcined carbon, which are the most representative of such materials, those in which carbon, nickel, titanium, silver, etc. are surface-treated on the surface of copper or stainless steel, or aluminum-cadmium alloy, etc. am. In addition, the negative electrode current collector 1021 may form fine irregularities on the surface in order 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, a sheet, a foil, a net, a porous body, a foam, a non-woven body, and the like.
[47]
The negative electrode active material 1022 may include, for example, carbon such as non-graphitizable carbon or graphitic 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, elements of Groups 1, 2, and 3 of the periodic table, halogen; 0 < x = 1; 1 = y = 3; 1 = z = 8); lithium metal; lithium alloy; silicon-based alloys; Titanium-based compounds such as Li 4 Ti 5 O 12 ; tin-based alloys; MnO x , FeO x , CoO x , NiO x , CuO x , SnO, SnO 2 , PbO, PbO 2 , Pb 2metal oxides such as 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; It may be a Li-Co-Ni-based material or the like.
[48]
As a separator that insulates the electrodes 101 and 102 between the anode 101 and the cathode 102, a commonly known polyolefin-based separator or a composite separator in which an organic or inorganic composite layer is formed on the olefin-based substrate may be used. and is not particularly limited.
[49]
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 an electrolyte is injected to manufacture the secondary battery 1 .
[50]
2 is an assembly view of a pouch-type secondary battery 1 according to an embodiment of the present invention.
[51]
A pouch-type secondary battery 1 according to an embodiment of the present invention includes not only the electrode assembly 10, but also a plurality of electrode tabs 11 protruding from the positive electrode 101 and the negative electrode 102 to one side, respectively; a plurality of electrode leads 12 respectively connected to the electrode tabs 11 to transmit electricity generated inside the electrode assembly 10 to the outside; a battery case 13 for accommodating the electrode assembly 10 therein; and an insulating portion 14 that surrounds the electrode lead 12 , is sealed together with the battery case 13 , and includes a flame retardant.
[52]
In the process of manufacturing the secondary battery 1 , as described above, after the electrode assembly 10 is formed, the electrode assembly 10 is inserted into the battery case 13 , and the electrolyte is injected and then sealed.
[53]
As shown in FIG. 1 , the electrode assembly 10 includes an 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 are interposed between the inside and the 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 active material application portions 1013 and 1023 to which electrode active materials 1012 and 1022 are applied and active material uncoated portions 1014 to which electrode active materials 1012 and 1022 are not applied. , 1024), that is, it is composed of the uncoated region. 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. As shown in FIG. 2 , the electrode tabs 11 may protrude side by side from one side of the electrode assembly 10 in the same direction, but are not limited thereto and may protrude in different directions.
[54]
An electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 by spot welding or the like. A part of the electrode lead 12 is surrounded by the insulating portion 14 . The insulating part 14 is located limitedly in the sealing part 134 to which the upper case 131 and the lower case 132 of the battery case 13 are heat-sealed, and the electrode lead 12 is attached to the battery case 13 . glue it together In addition, 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. Accordingly, the insulating portion 14 is made of a non-conductive material that does not conduct electricity well. In general, as the insulating part 14, an insulating tape that is easy to attach to the electrode lead 12 and has a relatively thin thickness is often used. have.
[55]
Furthermore, the insulating part 14 according to an embodiment of the present invention may further include a flame retardant. Accordingly, it is possible to improve the thermal stability of the secondary battery 1 by protecting the cell from ignition sources such as external fire, flame, spark, and the like. These flame retardants are substances that inhibit the combustion reaction, and may include various flame retardants such as halogen-based flame retardants, phosphorus-based flame retardants, or inorganic compound flame retardants. A detailed description of the flame retardant will be described later.
[56]
The electrode leads 12 may extend in the same direction or in opposite directions depending on the formation positions of the positive electrode tab 111 and the negative electrode tab 112 . The material of the positive lead 121 and the negative lead 122 may be different 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). And 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.
[57]
In the pouch-type secondary battery 1 according to 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 a pouch. The battery case 13 accommodates and seals the electrode assembly 10 so that a portion of the electrode lead 12, that is, the terminal portion is exposed. As shown in FIG. 2 , the battery case 13 includes an upper case 131 and a lower case 132 . The lower case 132 has a cup portion 133 provided with an accommodating space 1331 accommodating the electrode assembly 10 , and the upper case 131 has the electrode assembly 10 in the battery case 13 . The accommodating space 1331 is covered from the top so as not to be separated to the outside. At this time, as shown in FIG. 2 , a cup part 133 having an accommodation space 1331 is also formed in the upper case 131 , so that the electrode assembly 10 may be accommodated therein. The upper case 131 and the lower case 132 may be manufactured by connecting one side to each other as shown in FIG. 2 , but is not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.
[58]
When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and the insulating part 14 is formed on a portion of the electrode lead 12 , the accommodation space 1331 provided in the lower case 132 . The electrode assembly 10 is accommodated therein, and the upper case 131 covers the accommodation space 1331 from the top. Then, when the electrolyte is injected therein and the sealing part 134 formed on the edges of the upper case 131 and the lower case 132 is sealed, the secondary battery 1 is manufactured.
[59]
3 is a plan view of a positive electrode 101 according to an embodiment of the present invention, and FIG. 4 is a positive electrode active material application part 1013 and a positive electrode active material uncoated part 1014 of the positive electrode 101 according to an embodiment of the present invention. is an enlarged view of some of the
[60]
According to an embodiment of the present invention, between the active material application portions 1013 and 1023 and the active material non-applied portions 1014 and 1024 of the electrodes 101 and 102, since the coating portion containing the flame retardant is coated, the positive electrode 101 and Even when the negative electrode 102 is in direct contact, safety can be secured by suppressing initial heat generation.
[61]
Accordingly, in the electrodes 101 and 102 according to an embodiment of the present invention, the active material application parts 1013 and 1023 in which the electrode active materials 1012 and 1022 are applied to at least one surface of the electrode current collectors 1011 and 1021 . ); active material non-applied parts 1014 and 1024 formed on one side of the active material application parts 1013 and 1023 and to which the electrode active materials 1012 and 1022 are not applied; and a coating part coated between the active material application parts 1013 and 1023 and the active material non-applied parts 1014 and 1024 and including a flame retardant.
[62]
In addition, the electrode assembly 10 according to an embodiment of the present invention includes a positive electrode active material application unit 1013 in which a positive electrode active material 1012 is applied to at least one surface of a positive electrode current collector 1011 , and the positive electrode active material application unit 1013 . ) formed on one side of the positive electrode active material uncoated portion 1014 to which the positive electrode active material 1012 is not applied, and the positive electrode active material application portion 1013 and the positive electrode active material uncoated portion 1014 coated between the portion 1014 and including a flame retardant anode 101 including a coating portion 1015; Formed on one side of the negative active material application portion 1023, the negative electrode active material application portion 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 a negative electrode 102 including an uncoated negative active material uncoated portion 1024; and a separator interposed between the anode 101 and the cathode 102 .
[63]
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 the positive active material 1012 on at least one surface of the positive electrode current collector 1011 . part that has been As shown in FIG. 3 , the positive electrode active material application unit 1013 is a portion of the positive electrode current collector 1011 coated with the positive electrode active material 1012 , and at this time, as described above, a conductive agent is applied to the positive electrode active material 1012 . and a binder may be mixed.
[64]
The positive active material uncoated portion 1014 is formed on one side of the positive active material applied portion 1013 in the positive electrode 101 and is a portion on which the positive active material 1012 is not applied. As described above, the positive electrode tab 111 may be formed by cutting the non-coated portion 1014 of the positive electrode active material or by connecting a separate conductive member. Since the positive electrode active material uncoated portion 1014 is formed on one side of the positive electrode active material application portion 1013 , it is formed on the same surface of the positive electrode current collector 1011 as shown in FIG. 4 .
[65]
While the secondary battery 1 is actually being used, an accident may occur due to a collision with the outside. For example, when a sharp object penetrates the secondary battery 1 and the positive electrode 101 and the negative electrode 102 directly contact, a short may occur. Such a short circuit may cause a large amount of gas to be generated at a high speed in a short time, a high temperature rise, and the like, and furthermore, a large explosion may occur, which may lead to a major accident. In general, when the positive electrode 101 and the negative electrode 102 are in contact, when the positive current collector 1011 and the negative current collector 1021 are in contact, the positive current collector 1011 and the negative active material 1022 are in contact, There are mainly four cases, such as a case where the positive active material 1012 and the negative electrode current collector 1021 come into contact with each other, and a case where the positive electrode active material 1012 and the negative electrode active material 1022 come into contact with each other.
[66]
Among them, in general, when the positive electrode current collector 1011 and the negative electrode active material 1022 come into contact with each other, the amount of heat generated is the largest and the highest temperature is rapidly reached, and the risk of explosion is greatest. Therefore, 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 101 is coated between the positive electrode active material application portion 1013 and the positive electrode active material uncoated portion 1014 and includes a positive electrode coating portion 1015 containing a flame retardant.
[67]
The flame retardant is a material that inhibits the combustion reaction, and may include various flame retardants such as halogen-based flame retardants, phosphorus-based flame retardants, or inorganic compound flame retardants.
[68]
Halogen-based flame retardants generally exhibit a flame retardant effect by substantially stabilizing radicals generated in the gas phase. Halogen-based flame retardants include, for example, tribromophenoxyethane, tetrabromobisphenol-A (TBBA), octabromodiphenyl ether (OBDPE), brominated epoxy oligomers, brominated polycarbonate oligomers, chlorinated paraffin, chlorinated polyethylene, alicyclic and chlorine-based flame retardants.
[69]
Phosphorus-based flame retardants generally produce polymetaphosphoric acid by thermal decomposition and exert a flame retardant effect by forming a protective layer or blocking oxygen by a carbon film produced by dehydration when polymetaphosphoric acid is produced. Examples of the phosphorus-based flame retardant include phosphates such as red, ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, alkyldiaryl phosphate, trialkyl phosphate, resorcinaol bisdiphenyl phosphate (RDP), and the like.
[70]
Inorganic compound flame retardants are generally decomposed by heat, releasing incombustible gases such as water, carbon dioxide, sulfur dioxide, hydrogen chloride, etc. By reducing the production of the product, it exerts a flame retardant effect. The inorganic compound flame retardant is, for example, aluminum hydroxide (Al(OH) 3 ), magnesium hydroxide (Mg(OH) 2 ), boric acid (BH 3 O 3 ), antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compound , borate, and calcium salts.
[71]
Among the above flame retardants, an inorganic compound flame retardant may be particularly preferably used. According to an embodiment of the present invention, such a flame retardant is included in the positive electrode coating portion 1015, and in particular, an inorganic compound flame retardant such as aluminum hydroxide (Al(OH) 3 ), magnesium hydroxide (Mg(OH) 2 ) or boric acid (BH). 3 O 3 ) is preferred. And in some cases, it may further include other additives that induce a synergistic flame retardant effect when mixed with the flame retardants exemplified above.
[72]
The positive electrode coating portion 1015 is coated between the positive electrode active material application portion 1013 and the positive electrode active material uncoated portion 1014, so that even when the positive electrode current collector 1011 and the negative electrode active material 1022 come into direct contact, the initial heat generation is suppressed for safety can be obtained
[73]
In particular, as shown in FIG. 4 , the positive electrode coating portion 1015 is preferably coated including the interface 1016 between the positive electrode active material application portion 1013 and the positive electrode active material uncoated portion 1014 . That is, when the positive electrode active material 1012 is first applied to the positive electrode active material application unit 1013, one end of the positive electrode active material 1012 has an interface 1016 between the positive electrode active material application unit 1013 and the positive electrode active material uncoated portion 1014. do. Then, the positive electrode coating part 1015 may be coated while partially covering one end of the applied positive electrode active material 1012 . Accordingly, even if the positive electrode coating portion 1015 is peeled off to some extent, the positive electrode current collector 1011 of the positive electrode active material uncoated portion 1014 may not be significantly exposed. Accordingly, it is possible to prevent the positive electrode current collector 1011 and the negative electrode active material 1022 from contacting through the partially peeled region of the positive electrode coating portion 1015 .
[74]
5 is a plan view of the negative electrode 102 according to an embodiment of the present invention, and FIG. 6 is a negative active material application part 1023 and a negative electrode active material uncoated part 1024 of the negative electrode 102 according to an embodiment of the present invention. is an enlarged view of some of the
[75]
According to an embodiment of the present invention, in the negative electrode 102 of the plurality of electrodes 101 and 102 included in the electrode assembly 10 , the negative electrode active material application part 1023 is at least one surface of the negative electrode current collector 1021 . The negative active material 1022 is applied to the portion. As shown in FIG. 5 , the negative active material application unit 1023 is a portion on which the negative active material 1022 is applied in the negative electrode current collector 1021 , and at this time, as described above, the negative active material 1022 is selectively applied to the negative electrode active material 1022 . Conductive agents, binders, fillers, and the like may be included.
[76]
The negative active material uncoated portion 1024 is formed on one side of the negative active material application portion 1023 of the negative electrode 102 and is a portion on which the negative active material 1022 is not applied. As described above, the negative electrode tab 112 may be formed by cutting the portion 1024 on which the negative electrode active material is not applied or by connecting a separate conductive member. Since the negative active material uncoated portion 1024 is formed on one side of the negative active material application portion 1023 , it is formed on the same surface of the negative electrode current collector 1021 as shown in FIG. 6 .
[77]
As described above, since the risk of explosion is greatest when the positive electrode current collector 1011 and the negative electrode active material 1022 come into contact, the negative electrode current collector 1021 is attached to the positive electrode current collector 1011 or the positive electrode active material 1012 . In case of contact, the risk of explosion is relatively small. Therefore, according to an embodiment of the present invention, the negative electrode coating portion containing the flame retardant is not coated on the negative electrode 102 .
[78]
7 is a plan view of a negative electrode 102a according to another embodiment of the present invention, and FIG. 8 is a negative electrode active material application portion 1023a and a negative electrode active material uncoated portion 1024a of the negative electrode 102a according to another embodiment of the present invention. is an enlarged view of some of the
[79]
When the negative electrode current collector 1021 contacts the positive electrode current collector 1011 or the positive electrode active material 1012 , the risk of explosion is relatively small, but this is the same as when the positive electrode current collector 1011 and the negative electrode active material 1022 come into contact with each other. It is only relative when compared, and safety is not guaranteed.
[80]
Therefore, according to another embodiment of the present invention, as shown in FIG. 7, the negative electrode 102a is coated between the negative electrode active material application portion 1023a and the negative electrode active material uncoated portion 1024a and includes a flame retardant negative electrode coating portion ( 1025a). Accordingly, even when the negative electrode current collector 1021 and the positive electrode current collector 1011 or the positive electrode active material 1012 are in direct contact, initial heat generation can be suppressed to ensure safety.
[81]
In particular, as shown in FIG. 8 , the negative electrode coating portion 1025a is preferably coated including the interface 1026a between the negative electrode active material application portion 1023a and the negative electrode active material uncoated portion 1024a. That is, when the negative active material 1022a is first applied to the negative active material application portion 1023a, one end of the negative electrode active material 1022a has an interface 1026a between the negative electrode active material application portion 1023a and the negative electrode active material uncoated portion 1024a. do. Then, the negative electrode coating portion 1025a may be coated while partially covering one end of the applied negative electrode active material 1022a. Accordingly, even if the negative electrode coating portion 1025a is peeled off to some extent, the negative electrode current collector 1021 of the negative electrode active material uncoated portion 1024a may not be largely exposed. Accordingly, it is possible to prevent the negative electrode current collector 1021 and the positive electrode current collector 1011 or the positive electrode active material 1012 from contacting through the partially peeled off region of the negative electrode coating portion 1025a.
[82]
Those of ordinary skill in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof. 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 construed as being included in the scope of the present invention.
Claims
[Claim 1]
an active material application unit in which an electrode active material is applied to at least one surface of an electrode current collector; an active material uncoated portion formed on one side of the active material applying portion, to which the electrode active material is not applied; and a coating part coated between the active material application part and the active material uncoated part and including a flame retardant.
[Claim 2]
The electrode according to claim 1, wherein the electrode current collector is a positive electrode current collector, and the electrode active material is a positive electrode active material.
[Claim 3]
The electrode according to claim 1, wherein the flame retardant includes a halogen-based flame retardant, a phosphorus-based flame retardant, or an inorganic compound flame retardant.
[Claim 4]
The electrode of claim 3 , wherein the flame retardant comprises Al(OH) 3 , Mg(OH) 2 or BH 3 O 3 .
[Claim 5]
The electrode according to claim 1, wherein the coating part includes an interface between the active material application part and the active material uncoated part.
[Claim 6]
The electrode according to claim 1, wherein the active material application part and the active material uncoated part are formed on the same surface of the electrode current collector.
[Claim 7]
A positive electrode active material application part coated with a positive electrode active material on at least one surface of a positive electrode current collector, a positive electrode active material uncoated part formed on one side of the positive electrode active material application part and not coated with the positive electrode active material, and the positive electrode active material application part and the positive electrode active material not applied a positive electrode coated between the anodes and comprising a positive electrode coating portion containing a flame retardant; a negative electrode comprising a negative active material coating unit coated with a negative active material on at least one surface of a negative electrode current collector, and a negative electrode active material uncoated portion formed on one side of the negative active material application unit, to which the negative active material is not applied; and a separator interposed between the positive electrode and the negative electrode.
[Claim 8]
The electrode assembly of claim 7 , wherein the negative electrode further comprises a negative electrode coating portion coated between the negative electrode active material application portion and the negative electrode active material uncoated portion and including a flame retardant.
[Claim 9]
A secondary battery comprising the electrode assembly according to claim 7 .
[Claim 10]
The apparatus of claim 7, further comprising: a plurality of electrode tabs respectively protruding from the positive electrode and the negative electrode to one side; a plurality of electrode leads respectively connected to the electrode tabs to transmit electricity generated inside the electrode assembly to the outside; a battery case accommodating the electrode assembly therein; and an insulating part that surrounds the electrode lead, is sealed together with the battery case, and includes a flame retardant.