KR102267537B1 - Electrode - Google Patents

Abstract

This application relates to an electrode, an electrode assembly and a battery. In the present application, an electrode capable of exhibiting characteristics of a low resistance and high capacity, an electrode assembly and a battery including the same may be provided.

Description

electrode {ELECTRODE}

This application relates to an electrode.

An electrode assembly used in a secondary cell or a fuel cell generally has a structure in which an anode and a cathode are stacked with a separator interposed therebetween. The positive electrode and the negative electrode have a structure in which an electrode tab is formed on a current collector such as a metal foil, and an active material is coated, and is connected to a terminal by the electrode tab.

1 is an exemplary view of an electrode such as a positive electrode or a negative electrode. As shown in the drawing, in a general electrode, an electrode tab 20 is attached to one side of a conductive foil 10 which is a current collector, and an active material 30 is attached to the other side. It has a coated structure. However, since the electrode tab 20 is attached to the current collector 10 by welding, the active material 30 may be coated on the portion A of the current collector 10 corresponding to the electrode tab 20 attachment portion. There is a loss of capacity. Recently, attempts have been made to lower the resistance by forming a plurality of electrode tabs on the current collector. In this case, a decrease in capacity due to a decrease in the active material forming portion becomes more problematic.

This application relates to an electrode. In the present application, an electrode having a structure capable of simultaneously implementing low resistance and high capacity may be provided.

Among the physical properties mentioned in this specification, when the measured temperature affects the corresponding physical property, unless otherwise specified, the physical property is measured at room temperature. The term room temperature is a natural temperature that is not heated or reduced, for example, any temperature within the range of about 10°C to 30°C, may mean a temperature of about 23°C or about 25°C. In addition, unless otherwise specified, the unit of temperature in the present specification is °C.

In addition, when the measured pressure affects the physical properties among the physical properties mentioned in this specification, unless otherwise specified, the physical properties are measured at normal pressure, that is, atmospheric pressure (about 1 atm).

This application relates to an electrode. The electrode of the present application may be used as a positive electrode or a negative electrode of a fuel cell or a secondary battery, for example, a lithium-based secondary battery. The electrode of the present application includes a current collector and an electrode tab attached to at least one surface of the current collector. At least one or two or more electrode tabs may be attached to one surface of the current collector. At least one of the electrode tabs is attached to the current collector and the pressure-sensitive adhesive layer. In this case, the pressure-sensitive adhesive layer includes an electrical conductor. In the above, the electrical conductor is a material through which electricity easily passes due to high conductivity, and may refer to a material commonly referred to as a conductor.

2 is a view exemplarily showing the structure of the electrode of the present application. As shown in the figure, the electrode tab 200 is attached to the current collector 100 as an adhesive layer 400, and the electrode tab 200 and the current collector ( 100) can be electrically connected.

The electrode of the present application may further include an electrode active material on the surface of the current collector to which the electrode tab is not attached. The type of the electrode active material applied in the present application is not particularly limited, and all kinds of electrode active materials (positive electrode active material or negative electrode active material, etc.) applicable for electrode configuration may be applied. In the electrode structure of the present application, since the electrode tab is not attached by welding as in the prior art, but is attached by an adhesive layer, the electrode active material can be formed even in an area where the electrode active material could not be formed as in the conventional structure shown in FIG. 1 .

For example, as shown in FIG. 2 , in the electrode structure of the present application, the electrode active material 300 may be formed on the opposite side to the surface to which the electrode tab 200 of the current collector 100 is attached.

In one example, the electrode of the present application has two or more electrode tabs 200 on one surface of the current collector 100, for example, 2 to 10, 2 to 9, 2, as shown in FIGS. 3 or 4 . It may have a structure in which 8 to 8, 2 to 7, 2 to 6, 2 to 5, 2 to 4, or 2 or 3 electrode tabs 200 are attached.

3 or 4, when two or more electrode tabs are attached, all of the electrode tabs may be attached with the above-described pressure-sensitive adhesive layer, and some of them may be attached by welding as in a known method.

The structure in which the plurality of electrode tabs are formed as described above can implement a structure in which the plurality of electrode tabs are connected to external terminals, which is advantageous in realizing low resistance characteristics. In the conventional method, it was not easy to achieve a high capacity by risking a loss of an electrode active material when implementing a low resistance characteristic. However, in the structure of the present application, unlike the conventional method, an electrode having a low resistance and high capacity characteristic can be formed without loss of an active material.

The type of the current collector applied in the present application is not particularly limited, and a conventional secondary battery, for example, an electrode generally applied to an electrode such as a lithium secondary battery or a fuel cell may be used. As a current collector, a conductive foil, a film, a sheet, a net, a porous body or a nonwoven body, for example, a metal foil, a film, a sheet, a net, a porous body or a nonwoven body is used. Specifically, the current collector may be, for example, a foil, a film, or a sheet including stainless steel, aluminum, nickel, titanium, copper, or aluminum. Surface treatment using carbon, nickel, titanium, silver, etc. may be performed on the surface of the current collector, and fine irregularities may be formed. The unevenness may help to improve adhesion with the active layer. A method of forming the unevenness by roughening the surface of the current collector is not particularly limited, and, for example, a known method such as a mechanical polishing method, an electrolytic polishing method, or a chemical polishing method may be applied.

The current collector may have various forms such as, for example, a film, a sheet, a foil, a net, a porous body, a foamed body, or a nonwoven body.

The thickness of the current collector is not particularly limited, and may be set within an appropriate range in consideration of mechanical strength, productivity, battery capacity, and the like.

There is no particular limitation on the material of the electrode tab attached to the current collector, and a material applied to a general electrode configuration may be appropriately selected. Typically, the electrode tab is made of an electrical conductor such as a metal or a metal alloy. For example, the electrode tab may include stainless steel, aluminum, nickel, titanium, copper, sintered carbon or aluminum, etc., if necessary. , The surface of the electrode tab may be surface-treated using carbon, nickel, titanium, silver, or the like. In addition, the electrode tab may be made of the same material as the current collector.

In the structure of the electrode of the present application, the electrode tab is attached to the current collector by an adhesive layer, and the adhesive layer includes an electrical conductor.

In the present application, the type of the electrical conductor included in the pressure-sensitive adhesive layer is not particularly limited, and may be selected so as to electrically connect the current collector and the electrode tab by imparting appropriate electrical conductivity to the pressure-sensitive adhesive layer. For example, as the electrical conductor, a metal or a metal alloy may be used. For example, stainless steel, aluminum, nickel, titanium, copper, calcined carbon or aluminum, or an alloy of two or more thereof may be used. have.

The shape of the electrical conductor is also not particularly limited. For example, the electrical conductor may be a particle, and the shape of the particle may be plate-like, spherical, and other shapes.

The size of the electrical conductor may also be adjusted in consideration of, for example, the desired electrical conductive properties of the pressure-sensitive adhesive layer or the thickness of the pressure-sensitive adhesive layer, and is not particularly limited. For example, when an electrical conductor in the form of particles is applied, the D50 size may be about 0.1 μm to 10 μm, but is not limited thereto. In the above, the D50 size is the diameter at 50% accumulation (average particle diameter) measured on a volume basis in a particle size distribution meter measured by laser diffraction method, also known as the so-called Median diameter. In another example, the D50 size may be about 0.5 μm or more or 0.7 μm or more, or about 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, or 4 μm or less. However, the size of the electrical conductor may be changed according to the purpose.

In one example, when the current collector is a film, sheet, foil, net, porous body, foam or non-woven body including the above-described metal or metal alloy, the electrical conductor included in the pressure-sensitive adhesive layer is also the collector. The same as the whole metal or metal alloy can be applied. As described above, when the electrical conductor of the current collector and the pressure-sensitive adhesive layer is made of the same type of metal or metal alloy, it is possible to prevent the problem of metal precipitation due to oxidation/reduction reaction due to charging and discharging when the electrode is used.

In the electrode of the present application, the type of the pressure-sensitive adhesive layer including the electrical conductor is not particularly limited. That is, as the pressure-sensitive adhesive, a known pressure-sensitive adhesive capable of securing appropriate adhesive strength, high-temperature stability, and electrolyte resistance among known pressure-sensitive adhesives may be applied.

For example, as the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, an olefin-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, an EVA (ethylene vinyl acetate)-based pressure-sensitive adhesive, or a silicone-based pressure-sensitive adhesive may be used. The pressure-sensitive adhesives, respectively, are pressure-sensitive adhesives including an acrylic resin, an epoxy-based resin, a urethane-based resin, an olefin-based resin, a urethane-based resin, an EVA (ethylene vinyl acetate)-based resin, or a silicone-based resin as a main component among resin components. For example, each of the adhesives may include about 70% or more, about 75% or more, about 80% or more, about 85% or more, or about 90% or more of the above-mentioned resin in the resin component by weight. . The ratio may be about 99% or less or about 95% or less.

The type of the pressure-sensitive adhesive layer is also not limited, such as solvent-based, water-based or solvent-free, and may be a cured type or an uncured type. In the case of the curing type, the curing method is also not limited, such as a thermosetting method, a room temperature curing method, a moisture curing method, and an active energy ray curing method.

As the pressure-sensitive adhesive layer, an acrylic pressure-sensitive adhesive containing an acrylic resin as a main component may be used. The acrylic pressure-sensitive adhesive may be a cured product of the pressure-sensitive adhesive composition. The term acrylic resin is a polymer containing an acrylic monomer unit as a main component. As used herein, the term "unit of a monomer included in a polymer" means a state in which the monomer is included in the polymer through a polymerization reaction. In addition, in the present specification, that a certain component A is included as a main component in another component B means that the ratio of component A in component B is about 55% by weight or more, 60% by weight or more, 65% by weight or more based on the total weight of component B. Weight % or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, or 90% by weight or more may mean a case of being included. The upper limit of the ratio is not particularly limited, and may be, for example, about 98% by weight or less or 95% by weight or less.

As used herein, the term acrylic monomer means acrylic acid or methacrylic acid, or a derivative of acrylic acid or methacrylic acid, such as acrylic acid ester or methacrylic acid ester. In addition, in this specification, the term (meth)acryl means acryl or methacryl.

In the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive of the present application, the acrylic resin may be included as a main component.

The acrylic resin may be an adhesive polymer or an adhesive polymer. The term adhesive or adhesive polymer refers to a polymer whose physical properties, such as glass transition temperature, are adjusted so that adhesive performance or adhesive performance can be expressed before and/or after crosslinking, and the composition of such a polymer is well known in the art.

In one example, the acrylic resin may include an alkyl (meth)acrylate unit. In the above, the alkyl group included in the alkyl (meth)acrylate may be a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 4 to 8 carbon atoms. .

Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate or isopropyl (meth)acrylate, n-butyl (meth)acrylate, t -Butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth) Acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate may be exemplified, and one or two or more of the above may be exemplified. can be applied. Generally, n-butyl acrylate, 2-ethylhexyl acrylate, etc. are used.

The alkyl (meth)acrylate unit may be included as a main component in the acrylic resin.

The acrylic resin may also be a crosslinkable polymer having a crosslinkable functional group. The crosslinkable functional group may be introduced by including a unit of a monomer having a crosslinkable functional group (hereinafter, may be referred to as a crosslinkable monomer) in the polymer. As the crosslinkable functional group in the above, a hydroxyl group or a carboxyl group may be generally applied. In the present application, an acrylic resin including a hydroxyl group as a crosslinkable functional group may be referred to as a hydroxyl group-containing acrylic resin, and an acrylic resin including a carboxyl group may be referred to as a carboxyl group-containing acrylic resin.

As the crosslinkable monomer, for example, a hydroxyl group-containing monomer or a carboxyl group-containing monomer may be applied. Specific types of each of the crosslinking monomers are not particularly limited, and monomers known in the art may be used.

For example, the hydroxy group-containing monomer is a hydroxyalkyl (meth)acrylate having a hydroxyalkyl group having 1 to 12 carbon atoms, hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth) ) acrylate, 4-hydroxybutyl (meth) acrylate and/or 6-hydroxyhexyl (meth) acrylate may be used, and as the carboxyl group-containing monomer, (meth) acrylic acid, 2- (meth) Acryloyloxy acetic acid, 3-(meth)acryloyloxy propyl acid, 4-(meth)acryloyloxy butyric acid, acrylic acid duplex, itaconic acid, maleic acid and/or maleic anhydride and the like can be used. .

In general, a carboxyl group-containing monomer is often used among the above monomers for realization of high peel strength, but in the present application, a suitable monomer may be selected and applied according to the purpose. In particular, as will be described later, there are cases in which better effects can be realized by selecting a crosslinkable functional group according to the type of the electrical conductor.

The ratio of the crosslinkable monomer unit is not particularly limited as it is selected in consideration of the desired cohesive force, etc., but is generally included in the polymer within the range of about 0.01 to 10 parts by weight relative to 100 parts by weight of the alkyl (meth)acrylate unit. can In another example, the ratio of the monomer unit is about 0.05 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, 2.5 parts by weight or more, 3 parts by weight or more, It may be 3.5 parts by weight or more, 4 parts by weight or more, 4.5 parts by weight or more, or 5 parts by weight or more, and 9.5 parts by weight or less, 9 parts by weight or less, 8.5 parts by weight or less, 8 parts by weight or less, 7.5 parts by weight or less, 7 parts by weight or less. or less, 6.5 parts by weight or less, 6 parts by weight or less, 5.5 parts by weight or less, 5 parts by weight or less, 4.5 parts by weight or less, 4 parts by weight or less, 3.5 parts by weight or less, 3 parts by weight or less, or 2.5 parts by weight or less.

The acrylic resin may contain other monomer units if necessary in addition to the above-mentioned monomer units, and the type thereof is not particularly limited. For example, a monomer unit known in the art that can be applied to control the glass transition temperature or adhesive strength of the acrylic pressure-sensitive adhesive may be used.

The acrylic resin may have a weight average molecular weight (Mw) of 500,000 or more. In the present application, the term "weight average molecular weight" is a standard polystyrene conversion value measured by Gel Permeation Chromatograph (GPC), and may simply be referred to as molecular weight. The molecular weight (Mw) is, in another example, about 600,000 or more, about 700,000 or more, about 800,000 or more, about 900,000 or more, about 1 million or more, about 1.1 million or more, about 1.2 million or more, about 1.3 million or more, about 1.4 million or more, 1.5 million or more, 1.6 million or more, or 1.7 million or more, or about 3 million or less, about 2.8 million or less, about 2.6 million or less, about 2.4 million or less, about 2.2 million or less, about 2 million or less; It may be 1.9 million or less, 1.8 million or less, 1.6 million or less, 1.4 million or less, or 1.2 million or less.

The acrylic resin may also have a molecular weight distribution (PDI), that is, a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of greater than 1 or about 10 or less. The molecular weight distribution is about 1.2 or more, 1.5 or more, 1.8 or more, 2 or more, 2.2 or more, 2.4 or more, 2.6 or more, or 2.8 or more, or 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3.5 or less. , 3 or less, or 2.5 or less.

The molecular weight distribution may also be measured by a known method to which Gel Permeation Chromatograph (GPC) is applied.

In addition, a suitable molecular weight and molecular weight distribution may be selected according to the type or ratio of the applied electrical conductor.

The pressure-sensitive adhesive composition may further include a crosslinking agent, and the crosslinking agent may be a component for crosslinking the acrylic resin. Accordingly, the pressure-sensitive adhesive layer may include a crosslinked product of the acrylic resin, and in this case, the acrylic resin may be crosslinked by the crosslinking agent in the crosslinked product.

As the crosslinking agent, a known crosslinking agent may be used without particular limitation, for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, or an aziridine-based crosslinking agent may be used.

The type of the crosslinking agent applied in the present application is not particularly limited. For example, the isocyanate-based crosslinking agent includes diisocyanate such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate. A reaction product of isocyanate or one or more of the above diisocyanates and a polyol (ex. trimethylol propane) may be used, and the epoxy-based crosslinking agent includes ethylene glycol diglycidyl ether, triglycidyl ether, trimethylol At least one selected from the group consisting of propane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine and glycerin diglycidyl ether may be used, and the aziridine-based crosslinking agent includes N,N -Toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylene melamine, bisisopro At least one selected from the group consisting of taloyl-1-(2-methylaziridine) and tri-1-aziridinylphosphine oxide may be used.

The crosslinking agent may be used in an amount of 10 parts by weight or less or 0.001 parts by weight to 10 parts by weight based on 100 parts by weight of the acrylic resin, and under this ratio, the cohesive force, adhesion, high temperature stability, and electrolyte resistance of the crosslinked product can be properly maintained. have. In another example, the proportion of the crosslinking agent may be about 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.02 parts by weight or more, and about 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less. or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1.5 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, 0.4 parts by weight or less, 0.3 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less or less or 0.05 parts by weight or less.

The pressure-sensitive adhesive composition may include the aforementioned electrical conductor. As the electrical conductor, the kind described above can be used. The proportion of the electric conductor included in the pressure-sensitive adhesive composition is not particularly limited, and for example, the proportion of the conductor in the pressure-sensitive adhesive layer may be adjusted to be about 1 to about 80% by weight. In another example, the proportion of the conductor in the pressure-sensitive adhesive layer is about 3 wt% or more, 5 wt% or more, 7 wt% or more, 9 wt% or more, 11 wt% or more, 13 wt% or more, or 15 wt% or more, or 78 wt% % or less, 76 wt% or less, 74 wt% or less, 72 wt% or less, 70 wt% or less, 68 wt% or less, 66 wt% or less, 64 wt% or less, 62 wt% or less, 60 wt% or less, 58 wt% or less % or less, 56 wt% or less, 54 wt% or less, 42 wt% or less, 50 wt% or less, 48 wt% or less, 46 wt% or less, 44 wt% or less, 42 wt% or less, 40 wt% or less, 38 wt% or less % or less, 36 wt% or less, 34 wt% or less, 32 wt% or less, 30 wt% or less, 28 wt% or less, 26 wt% or less, 24 wt% or less, 22 wt% or less, 20 wt% or less, 18 wt% or less % or less, 16 wt% or less, or 14 wt% or less, but is not limited thereto.

The pressure-sensitive adhesive composition may further include other necessary known additives in addition to the components described above. Examples of such additives include coupling agents such as silane coupling agents, antistatic agents, tackifiers, ultraviolet stabilizers; antioxidants; toner; adjuvant; fillers; antifoam; Surfactants; photopolymerizable compounds such as polyfunctional acrylates; And one or more selected from the group consisting of a plasticizer may be exemplified, but is not limited thereto.

A method of manufacturing the electrode having the above-described structure by using the pressure-sensitive adhesive composition as described above is not particularly limited. For example, after forming a pressure-sensitive adhesive layer between two release films using the pressure-sensitive adhesive composition, one release film is peeled off, an electrode tab or a current collector is attached to the lifted pressure-sensitive adhesive layer, and then the other release film is peeled off. A method of attaching a current collector or electrode tab, or after forming an adhesive layer using the pressure-sensitive adhesive composition on a release film, attaching an electrode tab or current collector to the surface, and peeling the release film again, then the current collector or electrode A method of attaching the tab or a method of attaching the electrode tab or the current collector again after forming the pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition on the current collector or the electrode tab may be used. In the above method, after forming the pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition on the current collector or the electrode tab, before attaching the electrode tab or the current collector again, a release film may be temporarily attached to the surface thereof.

In addition, the method of forming the pressure-sensitive adhesive layer in the above is not particularly limited, and an appropriate curing method may be applied in consideration of the composition to the applied pressure-sensitive adhesive composition.

According to the type of the electrode, the structure of the electrode or the composition of the pressure-sensitive adhesive layer and/or the type of the electric conductor may be adjusted to secure suitable physical properties.

For example, in the case of a cathode, a foil, film, sheet, etc. containing copper or a copper alloy is usually used as a current collector. In this case, copper or a copper alloy is also used as an electrical conductor included in the pressure-sensitive adhesive layer. Can be used. In addition, in this case, as the acrylic resin in the pressure-sensitive adhesive, it may be appropriate to use a carboxyl group-containing acrylic resin. In addition, if necessary, the molecular weight or molecular weight distribution of the acrylic resin may be adjusted. In this case, the acrylic resin may not contain a crosslinkable functional group other than a carboxyl group, for example, a hydroxyl group, or the ratio thereof may be minimized. For example, the proportion of hydroxyl groups or the proportion of hydroxyl-containing monomer units in the acrylic resin is about 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, 0.2% by weight or less, 0.1% by weight or less, or 0.05% by weight or less, or , 0% by weight. In the case of such a negative electrode, at least three or more electrode tabs may be attached to the current collector, for example, three electrode tabs may be attached to the current collector as shown in FIG. 3 . In addition, in such a case, at least one of the three electrode tabs may be attached by the pressure-sensitive adhesive layer, some may be welded, or all electrode tabs may be attached by the pressure-sensitive adhesive layer.

Accordingly, the present application relates to a negative electrode having a specific structure according to an example, and the negative electrode includes a current collector; three or more electrode tabs attached to one surface of the current collector; and an anode active material on the other side of the current collector, wherein the current collector includes copper or a copper alloy, and at least one of the three or more electrode tabs is collected by a pressure-sensitive adhesive layer including copper or a copper alloy. It can be attached all over. The details of the structure are the same as previously described.

For example, in the negative electrode structure, the negative electrode active material may be present on the opposite side to the surface to which the electrode tab is attached of the current collector.

In addition, for example, in the case of an anode, a foil, film, sheet, etc. containing aluminum or an aluminum alloy is usually used as a current collector, and in this case, aluminum or aluminum is also used as an electrical conductor included in the pressure-sensitive adhesive layer. alloys may be used. Also, in this case, as the acrylic resin in the pressure-sensitive adhesive, it may be appropriate to use an acrylic resin containing a hydroxyl group. In addition, if necessary, the molecular weight or molecular weight distribution of the acrylic resin may be adjusted. In this case, the acrylic resin may not contain a crosslinkable functional group other than a hydroxyl group, for example, a carboxyl group, or the ratio thereof may be minimized. For example, the proportion of carboxyl groups or the proportion of carboxyl group-containing monomer units in the acrylic resin is about 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, 0.2 wt% or less, 0.1 wt% or less, or 0.05 wt% or less Or, it may be 0% by weight. In the case of such a positive electrode, at least two or more electrode tabs may be attached to the current collector, and for example, two electrode tabs may be attached to the current collector as shown in FIG. 4 . In addition, in such a case, at least one of the two electrode tabs may be attached by the pressure-sensitive adhesive layer, some may be welded, or all of the electrode tabs may be attached by the pressure-sensitive adhesive layer.

Accordingly, the present application relates to a positive electrode having a specific structure according to an example, and the positive electrode includes: a current collector; two or more electrode tabs attached to one surface of the current collector; and a positive electrode active material on the other side of the current collector, wherein the current collector includes aluminum or an aluminum alloy, and at least one of the two or more electrode tabs is collected by a pressure-sensitive adhesive layer comprising aluminum or an aluminum alloy. It can be attached all over. The details of the structure are the same as previously described.

For example, in the positive electrode structure, the positive electrode active material may be present on a side opposite to the surface to which the electrode tab is attached of the current collector.

The present application also relates to an electrode assembly including the above electrode, positive electrode or negative electrode, or a battery including the electrode assembly.

The structure or material of the electrode assembly or battery may be a well-known structure, method or material other than the electrode of the present application described above.

For example, the electrode assembly may have a structure in which the above-mentioned two electrodes are stacked with a separator interposed therebetween, or a structure in which the positive electrode and the negative electrode are stacked with a separator interposed therebetween.

At this time, a known material is applied to the type of separator applied at this time, and the shape of the electrode assembly is also a cylindrical shape called a so-called jelly roll, or a known structure such as a plate shape is applied.

In addition, an electrolyte that can be applied to a battery including the electrode assembly, its shape, and the like, may be applied in a known appropriate manner.

In the present application, an electrode capable of exhibiting characteristics of a low resistance and high capacity, an electrode assembly and a battery including the same may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of the structure of the conventional electrode.
2 to 4 are schematic cross-sectional views of the electrode structure of the present application.
5 to 8 are optical micrographs of the pressure-sensitive adhesives of Examples 1 to 4.
9 to 11 are optical micrographs of the pressure-sensitive adhesive of Examples 5 to 7.
12 is a graph showing the resistance measurement results of the electrodes of Examples 1 to 4;
13 is a graph showing the resistance measurement results of the electrodes of Examples 5 to 7;
14 is a schematic diagram showing a method for evaluating the adhesive force of an electrode according to an embodiment.
15 to 18 are photographs showing the results of evaluating the adhesion of the electrode of the embodiment.

The electrode of the present application will be described in detail through Examples below, but the scope of the electrode is not limited to the Examples below.

1. Weight average molecular weight and molecular weight distribution

The weight average molecular weight and molecular weight distribution were measured using GPC under the following conditions. The measurement result was converted using standard polystyrene of Agilent system for preparation of the calibration curve.

<Weight average molecular weight measurement conditions>

Meter: Gel Permeation Chromatography (Waters Alliance System)

Column: PL Mixed B type

Detector: Refractive index detector

Column flow rate and solvent: 1 mL/min, Solvent: Tetrahydrofuran (THF)

Analytical temperature and measurement volume: 40°C, 200 μL

2. Solid content evaluation

The solid content was measured as follows.

<Solid content measurement procedure>

1) Measure the weight (A) of the aluminum dish.

2) Collect the adhesive polymer solution in an amount of 0.3 to 0.5 g (sample before drying) and put it in a weighed aluminum dish.

3) A solution of a polymerization inhibitor (hydroquinone) dissolved in ethyl acetate (concentration: 0.5 wt %) is added to the pressure-sensitive adhesive composition in a very small amount using a pipette.

4) Dry in an oven at 150°C for about 30 minutes to remove solvents, etc.

5) After cooling for 15 to 30 minutes at room temperature, measure the weight of the remaining components (the weight of the sample after drying).

6) Measure the solid content according to the following formula.

TSC (solids content, unit: %) = (DS - A)/(S+E) × 100

DS: weight of aluminum dish + weight of sample after drying (unit: g)

A: Weight of aluminum dish (unit: g)

S: Weight of sample before drying (unit: g)

E: Weight of removed components (solvent, etc.) (unit: g)

Preparation Example 1.

Nitrogen gas was refluxed, and ethylhexyl acrylate (EHA) and acrylic acid (AA) were added in a weight ratio of 98:2 (EHA:AA) to a 1 L reactor equipped with a cooling device, and ethyl acetate (EAc) as a solvent was put in. Then, after purging with nitrogen gas for 1 hour to remove oxygen, 0.03 parts by weight of azobisisobutyronitrile (AIBN) diluted in ethyl acetate as a reaction initiator was added, and reacted for 8 hours to obtain an adhesive polymer solution (A) prepared. The weight average molecular weight (Mw) of the adhesive polymer was about 1.8 million, and the molecular weight distribution (PDI) was about 2.1. In addition, the glass transition temperature of the adhesive polymer estimated by the FOX formula was about -83°C, and the solid content was about 24.0%.

Preparation Example 2.

Nitrogen gas is refluxed and n-butyl acrylate (BA) and 4-hydroxybutyl acrylate (HBA) are added in a weight ratio of 98:2 (BA:HBA) to a 1 L reactor equipped with a cooling device, Ethyl acetate (EAc) was added as a solvent. Then, after purging with nitrogen gas for 1 hour to remove oxygen, 0.03 parts by weight of azobisisobutyronitrile (AIBN) diluted in ethyl acetate as a reaction initiator was added and reacted for 8 hours to obtain an adhesive polymer solution (B) prepared. The weight average molecular weight (Mw) of the adhesive polymer was about 1.1 million, and the molecular weight distribution (PDI) was about 3.0. In addition, the glass transition temperature of the adhesive polymer estimated by the FOX formula was about -54°C, and the solid content was about 25.0%.

Example 1.

About 0.02 parts by weight of a crosslinking agent (Tetraglycidyl-4,4'-methylene dianiline) is added to the adhesive polymer solution (A) of Preparation Example 1 based on 100 parts by weight of the solid content of the solution (A), and the D50 particle size is about 1 to 3 A pressure-sensitive adhesive composition was prepared by mixing copper (Cu) particles having a level of about μm in an amount of about 10 parts by weight based on 100 parts by weight of the solid content of the solution (A).

Then, an anode having the structure shown in FIG. 3 was prepared using the pressure-sensitive adhesive composition. First, the pressure-sensitive adhesive composition is coated on the release-treated surface of the release film and dried, then the release-treated surface of another release film is attached to the coated surface, and the pressure-sensitive adhesive composition is cured by maintaining it at a temperature of about 60°C to 80°C. A pressure-sensitive adhesive layer of about 10 μm was formed.

5 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and it can be seen from the drawing that copper particles are uniformly dispersed in the pressure-sensitive adhesive.

One release film from among the release films present on both sides of the pressure-sensitive adhesive layer is peeled off, and after attaching the lifted pressure-sensitive adhesive layer to the copper foil (Cu Foil), the other release film is peeled again, and the copper electrode tab is placed on the lifted pressure-sensitive adhesive layer surface. The electrode tab was attached to the copper foil in the structure shown in FIG. As the copper foil and copper electrode tab applied above, those commonly used in the manufacture of the negative electrode were applied. Next, a negative electrode active material, which is generally applied to the manufacture of an electrode assembly, was applied to the surface of the copper foil to which the electrode tab was not attached, as shown in FIG. 3 to prepare a negative electrode.

Example 2.

About 0.02 parts by weight of a crosslinking agent (Tetraglycidyl-4,4'-methylene dianiline) was added to the adhesive polymer solution (A) obtained in Preparation Example 1 based on 100 parts by weight of the solid content of the solution (A), and the D50 particle size was about 1 to A negative electrode was prepared in the same manner as in Example 1, except that an adhesive composition prepared by mixing copper (Cu) particles having a level of about 3 μm in an amount of about 16 parts by weight based on 100 parts by weight of the solid content of the adhesive polymer solution (A) was used. did. 6 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and it can be seen from the drawing that copper particles are uniformly dispersed in the pressure-sensitive adhesive.

Example 3.

About 0.02 parts by weight of a crosslinking agent (Tetraglycidyl-4,4'-methylene dianiline) was added to the adhesive polymer solution (A) obtained in Preparation Example 1 based on 100 parts by weight of the solid content of the solution (A), and the D50 particle size was about 1 to A negative electrode was prepared in the same manner as in Example 1, except that an adhesive composition prepared by mixing copper (Cu) particles having a level of about 3 μm in an amount of about 25 parts by weight based on 100 parts by weight of the solid content of the adhesive polymer solution (A) was used. did. 7 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and it can be seen from the drawing that copper particles are uniformly dispersed in the pressure-sensitive adhesive.

Example 4.

About 0.02 parts by weight of a crosslinking agent (Tetraglycidyl-4,4'-methylene dianiline) was added to the adhesive polymer solution (A) obtained in Preparation Example 1 based on 100 parts by weight of the solid content of the solution (A), and the D50 particle size was about 1 to A negative electrode was prepared in the same manner as in Example 1, except that an adhesive composition prepared by mixing copper (Cu) particles having a level of about 3 μm in an amount of about 54 parts by weight based on 100 parts by weight of the solid content of the adhesive polymer solution (A) was used. did. 8 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and it can be seen from the drawing that copper particles are uniformly dispersed in the pressure-sensitive adhesive.

Example 5.

About 0.1 parts by weight of a crosslinking agent (TMP (trimethylol propane) Adduct Type XDI (m-xylylene diisocyanate-based trifunctional crosslinking agent)) was added to the adhesive polymer solution (B) of Preparation Example 2 based on 100 parts by weight of the solid content of the solution (B), A pressure-sensitive adhesive composition was prepared by mixing aluminum (Al) particles having a D50 particle size of about 1 to 3 μm in an amount of about 10 parts by weight based on 100 parts by weight of the solid content of the adhesive polymer solution (B). A positive electrode having the structure shown in Fig. 4. First, the pressure-sensitive adhesive composition was coated on the release-treated surface of the release film to a thickness of about 10 μm, dried, and then the release-treated surface of another release film was attached to the coated surface, A pressure-sensitive adhesive layer having a thickness of about 10 μm was formed by curing the pressure-sensitive adhesive composition by maintaining it at a temperature of about 60° C. to about 80° C. Figure 9 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and aluminum particles from the drawing One of the release films present on both sides of the pressure-sensitive adhesive layer is peeled off, and the surface of the pressure-sensitive adhesive layer is attached to the aluminum foil (Al Foil), and then another release film is released. The film was peeled off, and an aluminum electrode tab was attached to the surface of the pressure-sensitive adhesive layer that was lifted to the aluminum foil in the structure shown in Fig. 3. The aluminum foil and electrode tab applied above were those commonly used in the manufacture of positive electrodes. A positive electrode was prepared by coating a conventional positive electrode active material on the surface of the foil to which the tab is not attached, as shown in FIG. 4 .

Example 6.

About 0.1 parts by weight of a crosslinking agent (TMP (trimethylol propane) Adduct Type XDI (m-xylylene diisocyanate-based trifunctional crosslinking agent)) was added to the adhesive polymer solution (B) obtained in Preparation Example 2 based on 100 parts by weight of the solid content of the solution (B). , except that the pressure-sensitive adhesive composition prepared by mixing aluminum (Al) particles having a D50 particle size of about 1 to 3 μm with about 16 parts by weight based on 100 parts by weight of the solid content of the adhesive polymer solution (B) was used. A positive electrode was manufactured in the same manner as in Example 5. Fig. 10 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and it can be seen from the drawing that aluminum particles are uniformly dispersed in the pressure-sensitive adhesive.

Example 7.

About 0.1 parts by weight of a crosslinking agent (TMP (trimethylol propane) Adduct Type XDI (m-xylylene diisocyanate-based trifunctional crosslinking agent)) was added to the adhesive polymer solution (B) obtained in Preparation Example 2 based on 100 parts by weight of the solid content of the solution (B). , except that the pressure-sensitive adhesive composition prepared by mixing aluminum (Al) particles having a D50 particle size of about 1 to 3 μm with about 40 parts by weight based on 100 parts by weight of the solid content of the adhesive polymer solution (B) was used. A positive electrode was manufactured in the same manner as in Example 5. Fig. 11 is an optical micrograph of the pressure-sensitive adhesive layer formed as described above, and it can be seen from the drawing that aluminum particles are uniformly dispersed in the pressure-sensitive adhesive.

Test Example 1. Electrical resistance measurement (cathode)

The electrical resistance of the negative electrodes prepared in Examples 1 to 4 was evaluated in the following manner. First, a jelly roll electrode assembly of a general type was manufactured using the negative electrode and the positive electrode (Al electrode, Al tab attached by laser welding) prepared in Example 1, and a polyethylene-based separator. Thereafter, the AC resistance (mΩ) of the inner and outer tabs of the anode and the inner and outer tabs of the cathode of the electrode assembly manufactured in the above manner was measured using a conventional measuring device (HIOKI BT-3562). equipment), respectively. AC resistance (mΩ) was evaluated in the same manner for the negative electrodes of Examples 2 to 4, respectively.

12 is a view summarizing the AC resistance (mΩ) measured in the above manner, from the left side, the inner tab resistance evaluation result of the positive electrode of the electrode assembly using the negative electrode of Example 1, the outer tab of the positive electrode Tab) resistance evaluation result, inner tab resistance evaluation result of the negative electrode, outer tab resistance evaluation result of the negative electrode, inner tab resistance evaluation of the positive electrode of the electrode assembly using the negative electrode of Example 2 As a result, the outer tab resistance evaluation result of the positive electrode, the inner tab resistance evaluation result of the negative electrode, the outer tab resistance evaluation result of the negative electrode, the positive electrode of the electrode assembly using the negative electrode of Example 3 Inner Tab resistance evaluation result, Outer Tab resistance evaluation result of the positive electrode, Inner Tab resistance evaluation result of the negative electrode, Outer Tab resistance evaluation result of the negative electrode, Example 4 The inner tab resistance evaluation result of the positive electrode of the electrode assembly using the negative electrode, the outer tab resistance evaluation result of the positive electrode, the inner tab resistance evaluation result of the negative electrode, and the outer tab resistance of the negative electrode Resistance evaluation result. From the figure, the inner tab and outer tab resistance evaluation results of the negative electrode all showed a low resistance value of 20 mΩ or less, and the resistance decreased as the content of Cu particles increased, and in particular, the electrical resistance value It can be seen that the distribution deviation of In the above description, the inner tab and the outer tab are referred to as the center of the jelly roll-shaped electrode assembly, and the tab located close to the center is referred to as the inner tab, and the tab located far from the inner tab is referred to as the outer tab.

Test Example 2. Electrical Resistance Measurement (Anode)

The electrical resistance of the positive electrodes of Examples 5 to 7 was evaluated in the same manner as in Test Example 1. First, using the positive electrode and the negative electrode of Example 5 (Cu electrode, Cu Tab attached by laser welding), and a polyethylene-based separator, a general type of jelly roll electrode assembly was manufactured. Thereafter, the inner tab, the middle tab and the outer tab of the cathode of the electrode assembly manufactured in the above manner, and the outer tab of the anode AC resistance (mΩ) was evaluated in the same manner as in Test Example 1. AC resistance (mΩ) was evaluated in the same manner for the positive electrodes of Examples 6 and 7, respectively.

13 is a view summarizing the AC resistance (mΩ) measured in the above manner, the inner tab resistance evaluation result of the negative electrode of the electrode assembly using the positive electrode of Example 5 from the left side, the middle tab Resistance evaluation result, outer tab resistance evaluation result, outer tab resistance evaluation result of the positive electrode of the electrode assembly, inner tab resistance evaluation of the negative electrode of the electrode assembly using the positive electrode of Example 6 As a result, the middle tab resistance evaluation result, the outer tab resistance evaluation result, the outer tab resistance evaluation result of the positive electrode of the electrode assembly, the negative electrode of the electrode assembly using the positive electrode of Example 7 These are the inner tab resistance evaluation result, the middle tab resistance evaluation result, the outer tab resistance evaluation result, and the outer tab resistance evaluation result of the positive electrode of the electrode assembly. From the figure, the outer tab resistance of the positive electrode all exhibited a low resistance value of 20 mΩ or less, and the distribution deviation of the electrical resistance value was the most stable in Example 6. In the above, the inner tab, the middle tab, and the outer tab are named based on the center of the jelly roll-shaped electrode assembly, the tab located closest to the center is referred to as the inner tab, and the tab located farthest from the inner tab is referred to as the outer tab, When a tab exists between the tab and the outer tab, it is called an intermediate tab.

Test Example 3 Adhesion Measurement

The adhesive strength of the negative electrode or the positive electrode prepared in Examples was evaluated in the following manner. First, a jelly roll electrode assembly of a general type was prepared using the positive or negative electrode. Thereafter, as schematically shown in FIG. 14 , both sides of the electrode assembly J/R were fixed with a jig, and the electrode tab was pulled with a tensile tester to measure the shear force. The measurement was performed with respect to the electrode assembly (dry adhesion), and the same was measured even after storage for about 1 day in the electrolyte at room temperature (wet adhesion). FIG. 15 is a result of dry adhesive force measured for the electrode of Example 1, and fracture occurred in the electrode tab as shown in FIG. 15, which means that the shear strength due to the pressure-sensitive adhesive layer is higher than the strength of the electrode tab. FIG. 16 is a result of measuring wet adhesion, and it can be seen that breakage occurred in the electrode tab as shown in FIG. 15 . In addition, FIGS. 17 and 18 are the results of checking whether the electrode tab is detached after the dry adhesion test and whether the electrode tab is detached after the wet adhesion test, respectively. In any case, there is no detachment of the electrode tab, and in particular, in the wet adhesion measurement result, the internal electrolyte No penetration was confirmed. The same results were obtained in the measurement for Examples 2 to 7.

Claims (19)

current collector; and an electrode tab attached to the current collector with an adhesive,
The pressure-sensitive adhesive is formed of a pressure-sensitive adhesive composition comprising an electrical conductor,
The pressure-sensitive adhesive composition is an electrode comprising a cross-linked product of an acrylic copolymer containing a hydroxyl group or a carboxyl group. The electrode according to claim 1, further comprising an electrode active material on a surface of the current collector to which the electrode tab is not attached. The electrode according to claim 2, wherein the electrode active material is also present on a side opposite to the side to which the electrode tab is attached. The electrode according to claim 1, wherein the current collector is a foil, film, sheet, net, porous body, or non-woven fabric comprising a metal or a metal alloy. 5. The electrode of claim 4, wherein the electrical conductor comprises the same metal or metal alloy as the current collector. The electrode of claim 1 , wherein the current collector and the electrical conductor both comprise copper or a copper alloy. delete The electrode according to claim 6, wherein three or more electrode tabs are attached to the current collector. The electrode of claim 1 , wherein the current collector and the electrical conductor both comprise aluminum or an aluminum alloy. delete The electrode according to claim 9, wherein two or more electrode tabs are attached to the current collector. The electrode according to claim 1, wherein the electrical conductor is a particle having a D50 size in the range of 0.1 μm to 10 μm. The electrode according to claim 1, wherein the pressure-sensitive adhesive layer contains an electrical conductor in a proportion of 1 to 80 wt%. current collector; three or more electrode tabs attached to one surface of the current collector; and an anode active material on the other side of the current collector,
The current collector includes copper or a copper alloy,
At least one of the three or more electrode tabs includes copper or a copper alloy, and the negative electrode is attached to the current collector by a pressure-sensitive adhesive layer including a cross-linked product of an acrylic copolymer containing a carboxyl group. current collector; two or more electrode tabs attached to one surface of the current collector; and a positive active material on the other side of the current collector,
The current collector includes aluminum or an aluminum alloy,
At least one of the two or more electrode tabs includes aluminum or an aluminum alloy, and the positive electrode is attached to the current collector by a pressure-sensitive adhesive layer including a crosslinked product of an acrylic copolymer containing a hydroxyl group. An electrode assembly in which the two electrodes of claim 1 are stacked with a separator interposed therebetween. An electrode assembly in which the negative electrode of claim 14 and the positive electrode of claim 15 are stacked with a separator interposed therebetween. A cell comprising the electrode assembly of claim 16 . A cell comprising the electrode assembly of claim 17 .

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