KR20220057239A - Binder for anode of secondary battery, anode of secondary battery and secondary battery - Google Patents

Abstract

The present invention relates to a binder for a negative electrode of a secondary battery, a negative electrode of a secondary battery, and a secondary battery. Specifically, according to embodiments of the present invention, provided are a binder for a negative electrode of a secondary battery including an aqueous dispersion of an acid and an aromatic hydrocarbon-modified resin, a manufacturing method thereof, a negative electrode manufactured by using the same, and a secondary battery.

Description

Binder for negative electrode of secondary battery, negative electrode of secondary battery, and secondary battery

The present invention relates to a binder for a negative electrode of a secondary battery, a negative electrode for a secondary battery, and a secondary battery.

BACKGROUND ART A secondary battery is in the spotlight as a power source for not only small electronic devices such as portable computers, portable telephones, and cameras, but also large electronic devices such as electric vehicles and power storage devices.

The negative electrode of the secondary battery includes a current collector and a negative electrode active material layer, wherein the negative electrode active material layer includes a negative electrode active material and a binder.

Commonly known binders for negative electrodes of secondary batteries include polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), and polyolefin (PO)-based polymers.

Among them, PVDF has excellent interaction with a carbon-based negative active material such as graphite, and thus has a high binding force and is electrochemically stable. However, due to lack of flexibility, there is a problem in that the bond is broken according to the contraction and expansion of the negative active material during charging and discharging of the secondary battery, and the cycle characteristics of the secondary battery are deteriorated. In addition to this, since it is necessary to prepare a non-aqueous negative electrode slurry using an organic solvent, there is a problem of causing environmental pollution.

SBR is a particulate polymer produced by emulsion polymerization, and has the advantage of improving the capacity and initial charge/discharge efficiency of a secondary battery by being environmentally friendly and exhibiting excellent bonding strength even when used in a small amount. However, there is a problem in that the contact area with graphite is narrow, the binding force is poor, the thermal stability is low due to the presence of unsaturated double bonds inside the particles, and the cycle characteristics of the secondary battery are deteriorated.

The PO-based polymer has excellent electrolyte resistance and thermal stability, but due to the low adhesion of the non-polar polymer, the binding force with the anode active material and the electrode current collector during charging and discharging is lowered, and there is a problem of lowering the cycle characteristics of the secondary battery.

An object of the present invention is to provide a technology for securing excellent cycle characteristics even during long-term driving of a secondary battery by strengthening initial adhesion through modification of a PO-based polymer, while maintaining binding force during a charge/discharge process.

In embodiments of the present invention, a binder for a negative electrode of a secondary battery comprising an aqueous dispersion of an acid and an aromatic hydrocarbon-modified resin; its manufacturing method; Provided are a negative electrode and a secondary battery manufactured using the same.

Specifically, the acid and aromatic hydrocarbon-modified resin includes a polyolefin, and in particular, an acid functional group and an aromatic hydrocarbon-based pendant functional group located inside, at the terminal, or both of the molecule of the polyolefin. includes

In addition, the acid and aromatic hydrocarbon-modified resin is prepared by sequentially reacting a polyolefin-based resin with an acid and an aromatic compound.

In the binder for a secondary battery negative electrode of one embodiment, the aromatic hydrocarbon-based pendant functional group in the acid and aromatic hydrocarbon-modified resin induces π-π stacking interactions with the surface of the negative electrode active material, thereby increasing the initial adhesion While strengthening, it is possible to secure excellent cycle characteristics even during long-term driving of the secondary battery by maintaining binding force during the charging/discharging process.

In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from other components.

The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise", "comprising" or "have" are intended to designate the existence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that the existence or addition of numbers, steps, elements, or combinations thereof, is not precluded in advance.

In this specification, when each layer or element is referred to as being formed "on" or "over" each layer or element, it means that each layer or element is formed directly on each layer or element, or another layer. or that elements may be additionally formed between each layer, on an object, on a substrate.

In the present specification, unless otherwise defined, "copolymerization" may mean block copolymerization, random copolymerization, graft copolymerization, or alternating copolymerization, and "copolymer" means block copolymer, random copolymer, graft copolymer, or alternating copolymers.

In the present specification, "binder" may mean a solid content in which a solvent is not mixed, and "binder composition" may mean a solution in which a solvent is mixed with a "binder".

As used herein, the term "pendant functional group" refers to a functional group located inside, not at the end of the chain, of the chain compound, specifically, a functional group grafted directly or indirectly to the side chain of the chain compound, the cyclic compound It may be understood to include a functional group bonded directly or indirectly to a ring atom.

Since the present invention may have various changes and may have various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Binder for negative electrode of secondary battery

The binder for a polyolefin-based negative electrode known before one embodiment of the present invention, introduction of a copolymer monomer having a low glass transition temperature (Tg), elastomer blending (Elastomer blending) or a polar functional group (Polar functional group) through a method of substituting the adhesive force was intended to strengthen. However, they have limitations in storage stability, adhesive properties, and the like.

In order to overcome this limitation, in one embodiment of the present invention, the π-π stacking interaction was introduced into the binder system.

Specifically, in the exemplary embodiment, there is provided a binder for a negative electrode of a secondary battery, including; acid and aromatic hydrocarbon-modified resin.

More specifically, the acid and aromatic hydrocarbon-modified resin includes an acid functional group and an aromatic hydrocarbon-based pendant functional group located inside, at the terminal, or both of the polyolefin and the polyolefin molecule. do.

π-π stacking interactions are possible between the carbon-based material and the aromatic hydrocarbon.

An aromatic hydrocarbon-based pendant functional group in the acid and aromatic hydrocarbon-modified resin induces a π-π stacking interaction with the surface of the negative electrode active material, thereby enhancing adhesion.

Here, the π-π stacking interaction corresponds to a kind of van der Waals attraction, not a chemical bond. Accordingly, according to the contraction and expansion of the negative active material during charging and discharging of the secondary battery, the aromatic hydrocarbon-based pendant functional group in the acid and aromatic hydrocarbon-modified resin may repeat bonding and debonding with the negative active material.

As a result, the binder for the negative electrode of the embodiment maintains the binding strength to the negative electrode active material during the charging and discharging process of the secondary battery while exhibiting excellent initial adhesion, and excellent cycle characteristics can be secured even during long-term driving of the secondary battery. .

Hereinafter, the binder for the negative electrode of the embodiment will be described in more detail.

acid functional group

The non-polar polyolefin can be dispersed in an aqueous solvent by implementing excellent electrolyte resistance properties due to the non-polarity of the polyolefin, and introducing an acid functional group such as maleic anhydride into the molecule of the polyolefin, the terminal, or both.

In addition, although there is an effect of improving the adhesion by introducing the acid functional group, the adhesive force when the acid functional group is introduced alone is insufficient compared to the existing binder such as SBR, which can be supplemented by additionally introducing an aromatic hydrocarbon-based pendant functional group to be described later. can

The acid functional group may be derived from maleic anhydride.

Maleic anhydride has excellent denaturation reactivity by radical attack and can form an acid moiety by ring opening, which is advantageous in providing reactivity and stability of acid denaturation reaction.

Aromatic hydrocarbon-based pendant functional group

As mentioned above, the aromatic hydrocarbon-based pendant functional group may compensate for insufficient adhesion when the acid functional group is introduced alone.

The aromatic hydrocarbon-based pendant functional group may be derived from a monocyclic aromatic hydrocarbon or a polycyclic aromatic hydrocarbon having a binding energy of 40 to 100 kJ/mol with graphite.

When a pendant functional group whose binding energy with graphite falls within the above range exists as a functional group grafted directly or indirectly to the inside of the polyolefin molecule, specifically to the side chain, it effectively induces π-π stacking interaction with the surface of the negative electrode active material to effectively induce the initial Adhesion is strengthened, and the binding force can be maintained even during charging and discharging of the secondary battery.

Specifically, the aromatic hydrocarbon-based pendant functional group may be derived from at least one selected from the group consisting of benzene, naphthalene, anthracene, and pyrene. The above materials have binding energies with graphite of 48 kJ/mol (benzene), 73 kJ/mol (naphthalene), 88 kJ/mol (anthracene) and 95 kJ/mol (pyrene), respectively.

However, as long as the binding energy with graphite falls within the above range, the aromatic hydrocarbon-based pendant functional group is not particularly limited.

content of each functional group

The total amount of the acid functional group and the aromatic hydrocarbon-based pendant functional group may be 0.5 to 15 wt%, specifically 0.5 to 10 wt%, of the acid and aromatic hydrocarbon-modified resin (100 wt%).

In addition, based on 100 wt% of the total amount of the acid functional group and the aromatic hydrocarbon-based pendant functional group, the content of the aromatic hydrocarbon-based pendant functional group may be 30 to 90 wt%, and the content of the acid functional group is 10 to 70 wt% % by weight.

In this range, it is possible to more effectively induce a π-π stacking interaction with the surface of the negative electrode active material to strengthen the adhesion, and maintain the binding force even during charging and discharging of the secondary battery.

For reference, the content of each functional group may be measured using equipment such as NMR.

polyolefin

The polyolefin is a homopolymer or copolymer of C3 or higher, specifically C3 to C20 olefin, and the pendant functional group is not particularly limited as long as it contains a tertiary hydrogen that may be substituted. .

Specifically, the polyolefin may be a polypropylene-based homopolymer or copolymer. For example, the polyolefin is a polypropylene homopolymer, a propylene-ethylene copolymer, a propylene-butylene copolymer, and an ethylene-propylene-butylene terpolymer (ethylene-propylene). -butylene terpolymer) may be at least one selected from the group consisting of.

Structure of Acid and Aromatic Hydrocarbon Modified Resins

The acid- and aromatic hydrocarbon-modified resin may be represented by a structure including a repeating unit represented by the following Chemical Formula 1, a repeating unit represented by the following Chemical Formula 2, and a repeating unit represented by the following Chemical Formula 3:

[Formula 1]

[Formula 2]

In Formula 2,

L ₁ is a direct bond or NH, such as NH,

L ₂ is a direct bond, or substituted or unsubstituted C _1-10 alkylene, such as C ₁ alkylene (ie, CH ₂ ),

Ar ₁ is phenyl, naphthyl, anthracenyl, or pyrenyl,

[Formula 3]

R ₁ is a substituent represented by the following formula 3-1 or 3-2,

[Formula 3-1]

[Formula 3-2]

In Formulas 3-1 and 3-2, a dotted line is connected to Formula 3, respectively.

Formula 1 corresponds to an olefin-based repeating unit to which an acid and an aromatic hydrocarbon-based pendant functional group are not bonded, Chemical Formula 2 corresponds to a site (repeating unit) substituted by an aromatic hydrocarbon-based pendant functional group, and Chemical Formula 3 is an acid It corresponds to a site (repeating unit) substituted by a functional group.

Specifically, Chemical Formulas 3-1 and 3-2 are structures derived from unringed maleic anhydride and ring-opened maleic anhydride, respectively, and are substituted with tertiary hydrogens in the polyolefin.

In addition, in Formula 2, OH of ring-opened maleic anhydride is substituted with an aromatic hydrocarbon-based pendant functional group. This can be considered that the aromatic hydrocarbon-based pendant functional group is substituted for the tertiary hydrogen of the polyolefin through an acid functional group (specifically, ring-opened maleic anhydride).

In addition, the acid- and aromatic hydrocarbon-modified resin may be represented by a structure further comprising at least one of a repeating unit represented by the following Chemical Formula 4 and a repeating unit represented by the following Chemical Formula 5:

[Formula 4]

[Formula 5]

.

.

The repeating unit represented by Chemical Formula 4 corresponds to an ethylene-based repeating unit, and the repeating unit represented by Chemical Formula 5 corresponds to a butylene-based repeating unit.

When the polyolefin is a polypropylene homopolymer, the acid and aromatic hydrocarbon-modified resin may include only the repeating unit represented by Formula 1, the repeating unit represented by Formula 2, and the repeating unit represented by Formula 3 above.

On the other hand, when the polyolefin is a propylene-ethylene copolymer, a propylene-butylene copolymer, or an ethylene-propylene-butylene terpolymer, the acid and aromatic hydrocarbon-modified resin is a repeating unit represented by Formula 1, Formula 2 In addition to the repeating unit represented by and the repeating unit represented by Chemical Formula 3, it may further include one or more of the repeating unit represented by Chemical Formula 4 and the repeating unit represented by Chemical Formula 5 below.

For example, the polyolefin may be a propylene-ethylene copolymer, wherein the acid and aromatic hydrocarbon-modified resin include a repeating unit represented by Formula 1, a repeating unit represented by Formula 2, a repeating unit represented by Formula 3, and the It may include a repeating unit represented by the formula (4).

aqueous solvent

In the binder for the negative electrode of the embodiment, an aqueous solvent, that is, water may be added to form a composition.

The aqueous solvent is, in terms of stability and viscosity control of the acid and aromatic hydrocarbon-modified resin, about 50 to about 1,000 parts by weight, specifically about 100 to about 400 parts by weight, based on 100 parts by weight of the acid and aromatic hydrocarbon-modified resin can be used as wealth. For example, in the total amount (100% by weight) of the binder for the negative electrode of the embodiment, it may be used so that the total solid content (TSC) is adjusted to about 10 to about 30%.

When the aqueous solvent is used too little, there may be a problem that the stability of the acid and aromatic hydrocarbon-modified resin is lowered, and when the solvent is used too much, the viscosity is lowered, and the process including coating properties when manufacturing the negative electrode Characteristics may be deteriorated, and thus the overall performance of the battery may be deteriorated.

Method for manufacturing a binder for a negative electrode of a secondary battery

In another embodiment of the present invention, by reacting a polyolefin-based resin with an acid (acid) to prepare an acid-modified resin; and reacting the acid-modified resin with an aromatic compound to prepare an acid and aromatic hydrocarbon-modified resin.

This corresponds to a method of preparing a binder for a negative electrode including the acid and aromatic hydrocarbon-modified resin of the above-described embodiment by sequentially reacting a polyolefin-based resin with an acid and an aromatic compound.

Hereinafter, a description overlapping with the above will be omitted, and the manufacturing method of the embodiment will be described in detail.

acid denaturation stage

In the step of preparing the acid-modified resin, hydrogen located inside, at the terminal, or both of the molecules of the polyolefin-based resin may be substituted with the acid.

Accordingly, it is possible to obtain an acid-modified resin comprising a polyolefin and an acid functional group located inside, at a terminal, or both of the polyolefin molecule.

Specifically, in the step of preparing the acid-modified resin, 1 to 30 parts by weight, specifically 1 to 20 parts by weight of an acid may be reacted based on 100 parts by weight of the polyolefin-based resin.

In this range, it is possible to finally obtain an acid and aromatic hydrocarbon-modified resin satisfying the above-mentioned acid value.

The preparing of the acid-modified resin may be performed in the presence of one or more solvents selected from the group consisting of toluene and xylene.

For example, it may be carried out under a toluene solvent.

In addition, in the step of preparing the acid-modified resin, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, tert-butylcumyl peroxide, benzoyl peroxide, dilauryl peroxide, and cumene hydride It may be carried out in the presence of one or more radical polymerization initiators selected from the group consisting of roperoxide.

For example, it may be carried out in the presence of dicumyl peroxide.

In addition, in the step of preparing the acid-modified resin, the acid may be maleic anhydride.

The maleic anhydride has excellent denaturation reactivity by radical attack of the radical polymerization initiator, and can form an acid moiety by ring opening, thereby providing reactivity and stability of the acid denaturation reaction. It is advantageous.

In addition, the step of preparing the acid-modified resin, 90 to 130 ℃, specifically in a temperature range of 100 to 120 ℃; It may be carried out for 4 to 8 hours, specifically 5 to 7 hours.

Within this temperature range and time range, hydrogen located inside, at the terminal, or both of the molecules of the polyolefin-based resin may be effectively substituted with the acid.

Aromatic hydrocarbon modification process

After the step of preparing the acid-modified resin, by reacting an aromatic compound, the tertiary hydrogen located inside the molecule of the acid-modified resin may be substituted with an aromatic hydrocarbon-based pendant functional group.

Accordingly, polyolefin and an acid and aromatic hydrocarbon-modified resin comprising an acid functional group and an aromatic hydrocarbon-based pendant functional group located inside, at the terminal, or both of the polyolefin molecule are obtained. can do.

Based on 100 parts by weight of the acid-modified resin, 1 to 30 parts by weight, specifically 1 to 20 parts by weight of the aromatic compound may be reacted.

In this range, it is possible to finally obtain an acid and aromatic hydrocarbon-modified resin satisfying the content of the aforementioned aromatic hydrocarbon-based pendant functional groups.

The step of preparing the acid and aromatic hydrocarbon-modified resin may be performed in a toluene solvent.

In addition, in the step of preparing the acid and aromatic hydrocarbon-modified resin, the aromatic compound is a monocyclic aromatic hydrocarbon or polycyclic aromatic hydrocarbon having a binding energy with graphite of 40 to 100 kJ/mol can

For example, it may be at least one selected from the group consisting of benzyl amine, naphthyl methylamine, anthracene methylamine, and pyrene methylamine.

In addition, the step of preparing the acid and aromatic hydrocarbon-modified resin, 90 to 130 ℃, specifically in a temperature range of 100 to 120 ℃; It may be carried out for 1 to 5 hours, specifically 2 to 4 hours.

Within this temperature range and time range, tertiary hydrogen positioned inside the molecule of the acid-modified resin may be effectively substituted with the aromatic hydrocarbon.

Steps for preparing aqueous dispersions

After the step of preparing the acid and aromatic hydrocarbon-modified resin, using an evaporation method, preparing an aqueous dispersion comprising the acid and the aromatic hydrocarbon-modified resin; may further include.

In other words, by further including this step, a composition comprising an aqueous solvent together with the acid and the aromatic hydrocarbon-modified resin (hereinafter, in some cases may be referred to as 'water dispersion' or 'aqueous dispersion') is obtained can do.

The aqueous dispersion thus obtained can be used to implement an aqueous negative electrode. Here, the aqueous negative electrode does not include a non-aqueous solvent, but refers to a negative electrode manufactured using a negative electrode mixture slurry composition containing an aqueous solvent.

Such an aqueous negative electrode is environmentally friendly because there is no concern about the generation of harmful substances in the negative electrode manufacturing process, compared to a negative electrode (non-aqueous negative electrode) manufactured using a negative electrode mixture slurry composition containing a non-aqueous solvent.

In the step of preparing an aqueous dispersion containing the acid and the aromatic hydrocarbon-modified resin, the acid and the aromatic hydrocarbon-modified resin are mixed with a low-boiling solvent having a boiling point of 100° C. or less and then heated to a solution in which the acid and the aromatic hydrocarbon-modified resin are dissolved manufacturing a; Dropping a basic solution to the solution in which the acid and the aromatic hydrocarbon-modified resin are dissolved; And after the basic solution is added dropwise, distilled water is added dropwise and the low boiling point solvent is added at the same time. While distilling, the step of dispersing the acid and the aromatic-modified resin in water; may further include.

The low boiling point solvent is a solvent below the boiling point (100 °C) of water, which is the final dispersion solvent, specifically 90 °C or lower, 80 °C or lower, or 70 °C or lower, and the lower limit is not particularly limited, but 10 °C or higher, 20 °C or higher, 30°C or higher, or 40°C or higher.

As the low boiling point solvent, acetone (boiling point: 56.5 °C), tetrahydrofuran (THF, boiling point: 66 °C), or a mixture thereof may be used, for example, tetrahydrofuran.

In the step of preparing a solution in which the acid and the aromatic hydrocarbon-modified resin are dissolved, the temperature is raised until it reaches a temperature range of 50 to 90 ℃, specifically 60 to 80 ℃, to obtain the acid and the aromatic hydrocarbon-modified resin with the tetrahydro It can be completely dissolved in furan.

Then, in the step of dropping the basic solution; in the solution, based on 100 parts by weight of the acid and aromatic hydrocarbon-modified resin in the solution in which the acid and the aromatic hydrocarbon-modified resin are dissolved, 0.1 to 10 parts by weight of the basic material, specifically 0.5 to 5 parts by weight The basic solution containing part can be dripped.

Here, the basic material is N,N-dimethylethanolamine, and the basic solution may be a solution obtained by dissolving N,N-dimethylethanolamine in tetrahydrofuran (THF).

By dropping the basic solution, the solubility in water is increased while converting the acid substituent into the water-soluble amine substituent form, thereby preparing a stable aqueous dispersion solution.

After dispersing the acid and the aromatic hydrocarbon-modified resin in water, cooling the aqueous dispersion of the acid and the aromatic hydrocarbon-modified resin to room temperature; and filtering the aqueous dispersion of the cooled acid and aromatic hydrocarbon-modified resin.

By further including these steps, it is possible to remove unreacted substances remaining in the aqueous dispersion of the acid and aromatic hydrocarbon-modified resin.

cathode

In another embodiment of the present invention, a negative electrode current collector; and a negative electrode mixture layer positioned on the negative electrode current collector and including the binder and the negative electrode active material of the above-described embodiment.

Except for the negative electrode binder of the embodiment, the negative electrode active material used for the negative electrode mixture and the negative electrode, the negative electrode current collector, etc. may each include generally known components.

The binder for the negative electrode of the embodiment may be included in an amount of 1% to 10% by weight, specifically 1% to 5% by weight of the total weight (100% by weight) of the negative electrode mixture. When this is satisfied, the content of the negative active material may be relatively increased, and the discharge capacity of the negative electrode may be further improved.

On the other hand, since the binder for a negative electrode of one embodiment has excellent properties in binding force and mechanical properties, etc., when a graphite-based negative electrode active material is used as the negative electrode active material of the negative electrode mixture, as well as a negative electrode active material having a higher capacity than that is used, the negative electrode The binding force between the active material and the negative electrode active material, between the negative electrode active material and the negative electrode current collector, etc. can be maintained, and expansion of the negative electrode active material can be suppressed by its own mechanical properties.

Since the binder for the negative electrode of one embodiment is suitable to be applied not only with the graphite-based negative active material but also with the negative active material having a higher capacity than that, in one embodiment of the present invention, the type of the negative electrode active material is not particularly limited.

Specifically, as the negative active material, carbon such as non-graphitizable carbon and graphite-based carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me' : metal composite oxides such as Al, B, 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; tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , metal oxides such as Bi ₂ O ₅ ; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxide; Lithium titanium oxide and the like can be used.

The negative electrode current collector is generally made to have a thickness of 3 μm to 500 μm. Such a negative current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel. Carbon, nickel, titanium, silver, etc. surface-treated, aluminum-cadmium alloy, etc. may be used. In addition, the bonding strength of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwovens.

The negative electrode is manufactured by coating the negative electrode mixture including the negative electrode active material and the binder on the negative electrode current collector, drying and rolling, and, if necessary, may be prepared by further adding a conductive material, a filler, and the like.

The conductive material is used to impart conductivity to the negative electrode, and any electronically conductive material can be used as long as it does not cause chemical change in the battery configured, for example, natural graphite, artificial graphite, carbon black, acetylene black, ketjen black , carbon-based materials such as carbon fibers; Metal-based substances, such as metal powders, such as copper, nickel, aluminum, and silver, or a metal fiber; conductive polymers such as polyphenylene derivatives; Alternatively, a conductive material including a mixture thereof may be used.

The filler is optionally used as a component for suppressing the expansion of the negative electrode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. A fibrous material such as glass fiber or carbon fiber may be used.

secondary battery

In another embodiment of the present invention, a secondary battery including the negative electrode of the embodiment described above is provided. Such a secondary battery, a positive electrode; electrolyte; and a negative electrode, and may be implemented as a lithium secondary battery.

The lithium secondary battery may be manufactured by impregnating an electrode assembly including a positive electrode, a separator, and a negative electrode with a non-aqueous electrolyte.

The negative electrode is the same as described above, and the remaining components will be described below.

anode

The positive electrode includes a positive active material, and the positive active material is 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 oxides such as Formula Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , and LiMnO ₂ ; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Ni site-type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ (wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); Formula LiMn _2-x M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (where M = Fe, Co, lithium manganese composite oxide represented by Ni, Cu or Zn; LiNi _x Mn _2-x O ₄ A lithium manganese composite oxide having a spinel structure; LiMn ₂ O ₄ in which a part of Li in the formula is substituted with an alkaline earth metal ion; disulfide compounds; Although Fe2 _{(MoO4)3 etc. are} mentioned, It is not limited only to these.

The positive electrode current collector is generally made to have a thickness of 3 μm to 500 μm. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Carbon, nickel, titanium, silver, etc. may be used on the surface of the surface-treated. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface thereof, and various forms such as a film, sheet, foil, net, porous body, foam body, and non-woven body are possible.

The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or 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; Conductive materials such as polyphenylene derivatives may be used.

A generally known binder may be used for the positive electrode. Representative examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, Polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or the like may be used, but is not limited thereto.

The negative electrode and the positive electrode may be prepared by mixing an active material and a binder, in some cases, a conductive material, a filler, and the like in a solvent to prepare a slurry-like electrode mixture, and applying the electrode mixture to each electrode current collector. Since such an electrode manufacturing method is widely known in the art, a detailed description thereof will be omitted herein.

In the case of the separator, any one commonly used in lithium batteries may be used as it separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. That is, a low-resistance to ion movement of the electrolyte and excellent electrolyte moisture content may be used. For example, it may be selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be in the form of a nonwoven fabric or a woven fabric. For example, a polyolefin-based polymer separator such as polyethylene or polypropylene is mainly used for lithium ion batteries, and a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and optionally single-layer or multi-layer structure can be used.

In some cases, a gel polymer electrolyte may be coated on the separator to increase battery stability. Representative examples of such a gel polymer include polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, and the like.

However, when a solid electrolyte other than the non-aqueous electrolyte is used, the solid electrolyte may also serve as a separator.

The non-aqueous electrolyte may be a liquid electrolyte including a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

As the non-aqueous electrolyte, a non-aqueous electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, and the like are used.

Examples of the non-aqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate , gamma-butylolactone, 1,2-dimethoxy ethane, 1,2-diethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, 4-methyl-1,3-dioxene, diethyl ether, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane Aprotic organic solvents such as derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyropionate, and ethyl propionate may be used. can

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, ions A polymer containing a sexually dissociating group or the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates, etc. of Li such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ and the like may be used.

The lithium salt is a material readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic lithium carboxylate, 4 phenyl lithium borate, and the like can be used.

In addition, for the purpose of improving charge/discharge characteristics, flame retardancy, etc. in the electrolyte, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitro Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. may be added. . In some cases, in order to impart incombustibility, a halogen-containing solvent such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high temperature storage characteristics, and FEC (fluoro-ethylene) carbonate), propene sultone (PRS), and fluoro-propylene carbonate (FPC) can be further included.

The lithium secondary battery according to the present invention may be used not only in a battery cell used as a power source for a small device, but also as a unit battery in a medium/large battery module including a plurality of battery cells.

Hereinafter, preferred embodiments are presented to help the understanding of the invention. However, the following examples are only for illustrating the invention, and do not limit the invention thereto.

<Example>

Example 1

(1) Preparation of binder composition for negative electrode

1) Preparation of acid-modified polyolefin resin

300 g of a polyolefin-based resin (poly(propylene-ethylene) copolymer, softening point 50° C., weight average molecular weight 160,000 g/mol), 30 g maleic anhydride and 450 g toluene were completely dissolved while uniformly stirring at 110° C. under a nitrogen atmosphere.

While maintaining the temperature in the flask at 110° C., 6 g of dicumyl peroxide as a radical polymerization initiator was slowly added for 1 hour. Thereafter, the reaction was further carried out for 5 hours or more so that the radical polymerization reaction could proceed completely.

After completion of the reaction, the reaction product was cooled to room temperature, and the product was poured into a large amount of acetone to precipitate an acid-modified polyolefin resin. The acid-modified resin thus obtained was washed with acetone three times to completely remove unreacted substances. Then, it was dried under reduced pressure at 60°C.

2) Preparation of acid and aromatic hydrocarbon-modified polyolefin resin

400 g of toluene was added to 200 g of the acid-modified polyolefin resin, and the temperature was raised to 110° C. to completely dissolve it. A solution of 10 g of naphthyl methylamine dissolved in 40 g of toluene was added and reacted at 110° C. for 3 hours.

After completion of the reaction, after cooling to room temperature, the product was poured into a large amount of acetone to precipitate an acid and aromatic hydrocarbon-modified polyolefin resin. The thus obtained acid and aromatic hydrocarbon-modified polyolefin resin was washed with acetone three times to completely remove unreacted substances. Then, it was dried under reduced pressure at 60°C.

3) Preparation of aqueous dispersion of polyolefin resin (production of negative electrode binder composition)

In a reactor equipped with a reflux condenser and a Dean-Stark device, 100 g of THF was added to 150 g of the acid and aromatic hydrocarbon-modified polyolefin resin, and the temperature was raised to 70° C. to completely dissolve it. A solution of 4.5 g of N,N-dimethylethanolamine dissolved in 30 g of THF as a basic compound was added dropwise over 1 hour. Then, 600 g of distilled water was added dropwise for 1 hour, while THF was slowly distilled through a Dean-Stark trap and dispersed in water. After cooling to room temperature, it was filtered through 300 mesh to prepare a final aqueous dispersion of polyolefin-based resin having a solid content of 20%.

(2) Preparation of negative electrode

Using water as a dispersion medium, 95 g of artificial graphite, 1.5 g of acetylene black, 100 g of carboxymethyl cellulose as a thickener (solids content of 1.0% by weight), and 12.5 g of the negative electrode binder composition of Example 1 (solids content of 20) based on 100 g of total solid content % by weight) and stirred for 1 hour to prepare a negative electrode mixture slurry composition having a total solid content of 45% by weight.

Prepare a copper foil with a thickness of 10 μm, use it as a negative electrode current collector, and use a comma coater to apply the negative electrode mixture slurry composition onto one surface of the negative electrode current collector at 8.0 mg/cm ² Loading (loading) After coating on both sides in an amount, hot air dried in an oven at 80° C. for 10 minutes, and then rolled to a total thickness of 190 μm. Thus, the negative electrode of Example 1 was obtained.

(3) Preparation of Lithium Ion Battery

LiNi _0.6 Mn _0.2 Co _0.2 O ₂ 90 g, acetylene black 5.0 g, and polyvinylidene fluoride (PVDF) 50 g (solid content 10% by weight) as a binder were used as a positive active material, and these were used in NMP as a solvent for 1 hour. A positive electrode mixture slurry composition was prepared by stirring so that the total solid content was 70% by weight.

Prepare an aluminum foil with a thickness of 20 μm and use it as a positive electrode current collector, and using a comma coater, apply the positive electrode mixture slurry composition to one surface of the positive electrode current collector at 15.6 mg/cm ² Loading (loading) After coating on both sides in an amount, hot air dried in an oven at 80 ° C. for 10 minutes, and then rolled to a total thickness of 190 μm. Thus, the positive electrode of Example 1 was obtained.

As the electrolyte, in a mixed solvent of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) (weight ratio of EC:PC:DEC=3:2:5) LiPF6 was dissolved so as to have a concentration of 1.3M, and an additive fluoroethylenecarbonate (FEC) of 10% by weight based on the total weight of the electrolyte was added.

Example 2

A negative electrode binder composition was prepared in the same manner as in Example 1, but in the aromatic hydrocarbon modification step, 6.4 g of naphthyl methylamine of Example 1 was used instead of 10 g, and the number of aromatic modified polyolefin resins In the dispersion preparation step, 5.9 g was used instead of 4.5 g of N,N-dimethylethanolamine, which is the basic compound of Example 1. Preparation of the negative electrode and the lithium ion battery were carried out in the same manner as in Example 1.

Example 3

A negative electrode binder composition was prepared in the same manner as in Example 1, but in the aromatic hydrocarbon modification step, 16 g of naphthyl methylamine of Example 1 was used instead of 10 g, and an aqueous dispersion of an aromatic modified polyolefin resin. In the preparation step, 1.8 g of N,N-dimethylethanolamine, which is the basic compound of Example 1, was used instead of 4.5 g. Preparation of the negative electrode and the lithium ion battery were carried out in the same manner as in Example 1.

Example 4

A negative electrode binder composition was prepared in the same manner as in Example 1, but 7 g of benzyl amine was used instead of 10 g of naphthyl methylamine of Example 1 in the aromatic hydrocarbon modification step. Preparation of the negative electrode and the lithium ion battery were carried out in the same manner as in Example 1.

Example 5

A negative electrode binder composition was prepared in the same manner as in Example 4, except that 24 g of maleic anhydride was used instead of 30 g of maleic anhydride in the acid modification step, and 4 g of benzyl amine of Example 4 in the step of modifying an aromatic hydrocarbon instead of 7 g was used, and in the step of preparing an aqueous dispersion of the aromatic modified polyolefin resin, 2.7 g of N,N-dimethylethanolamine, which is the basic compound of Example 4, was used instead of 4.5 g. Preparation of the negative electrode and the lithium ion battery were carried out in the same manner as in Example 1.

Example 6

A negative electrode binder composition was prepared in the same manner as in Example 1, but 18 g of pyrene methylamine was used instead of 10 g of naphthyl methylamine of Example 1 in the aromatic hydrocarbon modification step. Preparation of the negative electrode and the lithium ion battery were carried out in the same manner as in Example 1.

Comparative Example 1

After preparing an acid-modified polyolefin resin in the same manner as in Example 1, an aqueous dispersion (cathode binder composition) was prepared without modification of aromatic hydrocarbons. An aqueous dispersion was prepared in the same manner as in Example 1, but 9 g was used instead of 4.5 g of N,N-dimethylethanolamine, which is a basic compound. Preparation of the negative electrode and the lithium ion battery were carried out in the same manner as in Example 1.

Comparative Example 2

Instead of the negative electrode binder composition of Example 1, using 6.25 g of SBR latex dispersed in water (solid content 40%, styrene:butadiene = 60:40% by weight), the negative electrode and the lithium ion battery were prepared in the same manner as in Example 1 prepared.

Experimental example: evaluation of negative electrode and secondary battery

For Examples 1 to 6 and Comparative Examples 1 to 2, the negative electrode and the lithium secondary battery were evaluated under the following conditions, respectively, and the results are recorded in Table 1 below.

(1) Cathodic Adhesion

In a constant temperature chamber at 25° C., when the negative electrode mixture layer of each negative electrode is adhered to a glass substrate, and the negative electrode is pulled at a peeling rate of 5 mm/min and a peeling angle of 180°, the negative electrode of the negative electrode from the glass substrate The force at which the mixture layer was peeled was measured

(2) Cathode thickness change rate

Each of the prepared negative electrodes was supported in an electrolyte for 24 hours, and the thickness of the negative electrode before and after loading the electrolyte was measured with a thickness meter, respectively, and the negative electrode thickness change rate was evaluated according to the following [Equation 1]. Here, as the electrolyte, an electrolyte having the same composition as that used for manufacturing each lithium ion battery was used.

[Equation 1] Anode thickness change rate (%) = 100x [Thickness difference before and after electrolyte loading] /[Thickness before electrolyte loading]

(3) Capacity retention rate after 1000 cycles of battery

In a constant temperature chamber at 25° C., charging each lithium ion battery at 36 A to 4.15 V in CC/CV mode (mode) and then discharging in CC mode to 3.0 V as one cycle, A rest period of 20 minutes was placed between the charging and discharging, and a total of 1000 cycles were performed. The ratio of the discharge capacity measured in the 1000th cycle to the discharge capacity measured in the first cycle was calculated according to the following [Equation 2]

[Equation 2] Capacity retention rate (%) = 100×[discharge capacity after 1000 cycles] / [discharge capacity after 1 cycle]

cathodic adhesion
(gf/cm) Cathode thickness change rate
(%) Capacity retention rate of secondary battery after 1000 cycles (%) Example 1 40 0.1 91 Example 2 37 0.1 90 Example 3 38 0.1 88 Example 4 36 0.1 89 Example 5 35 0.1 84 Example 6 39 0.1 90 Comparative Example 1 30 0.1 85 Comparative Example 2 35 1.5 86

From Table 1, it can be seen that, compared to Comparative Examples 1 and 2, the negative electrode adhesion strength, thickness change rate, and capacity retention rate of the secondary battery of Examples 1 to 6 after 1000 cycles were excellently exhibited.

Specifically, in the case of SBR (Comparative Example 2) generally known in the art, although the initial adhesion is secured relatively high, it is confirmed that the thickness change before and after the electrolyte loading is severe.

In particular, the significant change in thickness before and after loading the electrolyte means that the SBR expands while being impregnated with the electrolyte and loses binding force to the negative electrode active material.

Although it was evaluated up to 1000 cycles at the laboratory scale, when it is operated for a long time beyond this, the SBR impregnated with the electrolyte further loses binding force to the anode active material according to the contraction and expansion of the anode active material, impairing the cycle characteristics of the secondary battery. predicted

On the other hand, in the case of the polyolefin-based resin modified only by acid (Comparative Example 1), the thickness change before and after the electrolyte loading was reduced compared to SBR (Comparative Example 2), but it was confirmed to have a low initial adhesive strength.

In this regard, excellent electrolyte resistance properties are realized due to the non-polarity of polyolefin, but the effect of improving adhesion by introducing the acid functional group alone is confirmed to be lower than that of SBR (Comparative Example 2).

On the other hand, in the case of the acid and aromatic hydrocarbon-modified resins (Examples 1 to 6), it was confirmed that high initial adhesion was ensured and the change in the thickness of the negative electrode was suppressed.

This means that excellent electrolyte resistance properties are realized due to the non-polarity of polyolefin, and the insufficient adhesive strength when the acid functional group is introduced alone is compensated for through the aromatic hydrocarbon-based pendant functional group.

Overall, by introducing an acid functional group and an aromatic hydrocarbon-based pendant functional group in the inside, terminal, or both of the molecules of the polyolefin, the initial adhesion and the electrolyte resistance properties can be simultaneously realized in an excellent range, thereby reducing the binding force during the charging and discharging process. It can be seen that excellent cycle characteristics can be secured even during long-term driving of the secondary battery.

Claims (20)

containing an acid and aromatic hydrocarbon modified resin;
The acid and aromatic hydrocarbon-modified resin,
polyolefin, and
Including an acid (acid) functional group and an aromatic hydrocarbon-based pendant (pendant) functional group located inside the molecule of the polyolefin, at the terminal, or both,
A binder for a negative electrode of a secondary battery.
According to claim 1,
The aromatic hydrocarbon-based pendant functional group,
It is derived from at least one selected from the group consisting of benzene, naphthalene, anthracene and pyrene,
A binder for a negative electrode of a secondary battery.
According to claim 1,
The acid functional group,
which is derived from maleic anhydride,
A binder for a negative electrode of a secondary battery.
According to claim 1,
The polyolefin is
A homopolymer or copolymer of a C3 to C20 olefin having a tertiary hydrogen;
A binder for a negative electrode of a secondary battery.
According to claim 1,
The polyolefin is
Polypropylene homopolymer, propylene-ethylene copolymer, propylene-butylene-copolymer and ethylene-propylene-butylene terpolymer At least one selected from the group comprising
A binder for a negative electrode of a secondary battery.
According to claim 1,
The acid and aromatic hydrocarbon-modified resin,
comprising a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3),
Binder for negative electrode of secondary battery:
[Formula 1]

[Formula 2]

In Formula 2,
L ₁ is a direct bond or NH, such as NH,
L ₂ is a direct bond, or substituted or unsubstituted C _1-10 alkylene, such as C ₁ alkylene (ie, CH ₂ );
Ar ₁ is phenyl, naphthyl, anthracenyl, or pyrenyl,
[Formula 3]

R ₁ is a substituent represented by the following formula 3-1 or 3-2,
[Formula 3-1]

[Formula 3-2]

In Formulas 3-1 and 3-2, a dotted line is connected to Formula 3, respectively.
According to claim 1,
The acid and aromatic hydrocarbon-modified resin,
Further comprising at least one of a repeating unit represented by the following formula (4) and a repeating unit represented by the following formula (5),
Binder for negative electrode of secondary battery:
[Formula 4]

[Formula 5]

.
According to claim 1,
The total amount of the acid functional group and the aromatic hydrocarbon-based pendant functional group is
0.5 to 15% by weight of the acid and aromatic hydrocarbon-modified resin (100% by weight),
A binder for a negative electrode of a secondary battery.
According to claim 1,
The binder composition,
Aqueous solvent; further comprising,
A binder for a negative electrode of a secondary battery.
preparing an acid-modified resin by reacting a polyolefin-based resin with an acid; and
By reacting the acid-modified resin with an aromatic compound, comprising the step of preparing an acid and aromatic hydrocarbon-modified resin,
A method of manufacturing a binder for a negative electrode of a secondary battery.
11. The method of claim 10,
In the step of preparing the acid-modified resin,
Based on 100 parts by weight of the polyolefin-based resin, 1 to 30 parts by weight of an acid is reacted,
A method of manufacturing a binder for a negative electrode of a secondary battery.
11. The method of claim 10,
The step of preparing the acid-modified resin,
carried out in the temperature range of 90 to 130 °C,
A method of manufacturing a binder for a negative electrode of a secondary battery.
11. The method of claim 10,
The step of preparing the acid and aromatic hydrocarbon-modified resin,
Reacting 1 to 30 parts by weight of an aromatic compound based on 100 parts by weight of the acid-modified resin,
A method of manufacturing a binder for a negative electrode of a secondary battery.
11. The method of claim 10,
The step of preparing the acid and aromatic hydrocarbon-modified resin,
carried out in the temperature range of 90 to 130 °C,
A method of manufacturing a binder for a negative electrode of a secondary battery.
11. The method of claim 10,
After the step of preparing the acid and aromatic hydrocarbon-modified resin,
Using a distillation method (evaporation method), preparing an aqueous dispersion containing the acid and the aromatic hydrocarbon-modified resin; further comprising,
A method of manufacturing a binder for a negative electrode of a secondary battery.
16. The method of claim 15,
The step of preparing an aqueous dispersion comprising the acid and aromatic hydrocarbon-modified resin,
preparing a solution in which the acid and aromatic hydrocarbon-modified resin are dissolved by mixing the acid and the aromatic hydrocarbon-modified resin with a low-boiling solvent having a boiling point of 100° C. or less and then heating the mixture;
Dropping a basic solution to the solution in which the acid and the aromatic hydrocarbon-modified resin are dissolved; and
After the basic solution is added dropwise, distilled water is added thereto and the low boiling point solvent is distilled off while dispersing the acid and the aromatic modified resin in water; further comprising:
A method of manufacturing a binder for a negative electrode of a secondary battery.
17. The method of claim 16,
The low boiling point solvent is
acetone, tetrahydrofuran, or a mixture thereof,
A method of manufacturing a binder for a negative electrode of a secondary battery.
17. The method of claim 16,
After the step of dispersing the acid and the aromatic hydrocarbon-modified resin in water,
cooling the aqueous dispersion of the acid and aromatic hydrocarbon-modified resin to room temperature; and
Further comprising; filtering the aqueous dispersion of the cooled acid and aromatic hydrocarbon-modified resin;
A method of manufacturing a binder for a negative electrode of a secondary battery.
negative electrode current collector; and
Located on the negative electrode current collector, the negative electrode mixture layer comprising the binder of claim 1 and the negative electrode active material; including,
negative electrode of the secondary battery.
The negative electrode of claim 19; anode; and electrolyte;
secondary battery.