KR102537231B1 - an anode active material, anode comprising the same, and lithium secondary battery comprising the anode - Google Patents

Abstract

The present invention includes a core comprising a carbon-based material; It relates to a negative electrode active material including a polycyclic ionic group-containing compound bonded to the surface of the carbon-based material, a negative electrode including the same, and a lithium secondary battery including the negative electrode.

Description

A negative active material, a negative electrode including the same, and a lithium secondary battery including the negative electrode {an anode active material, anode comprising the same, and lithium secondary battery comprising the anode}

It relates to a negative electrode active material, a negative electrode including the same, and a lithium secondary battery including the negative electrode.

Lithium batteries are used as power sources for portable electronic devices such as video cameras, mobile phones, and notebook computers. Rechargeable lithium secondary batteries have more than three times higher energy density per unit weight compared to conventional lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries, and are capable of high-speed charging.

In general, a lithium secondary battery uses a material capable of reversible intercalation and deintercalation of lithium ions as a positive electrode active material and a negative electrode active material, and an electrolyte between a positive electrode including the positive electrode active material and a negative electrode including the negative electrode active material It is prepared by filling

At this time, a carbon-based material whose stability has been verified is mainly used as an anode active material used in the anode of a lithium secondary battery, and an appropriate amount of a binder is used together to strengthen the contact between the anode active material and other materials included in the anode.

On the other hand, the negative electrodes that have been used in the past have problems in that a space is generated between the materials included in the negative electrode according to the volume change due to repeated charging and discharging, and the conductivity is lowered or the negative electrode active material is deteriorated due to a side reaction with the electrolyte. has been raised

In order to solve this problem, attempts have been made to modify the surface of an active material by acid-treating or heat-treating the surface of a negative electrode active material, for example, a carbon-based material. , and some of the covalent bonds on the carbon surface are decomposed, resulting in a decrease in conductivity.

Therefore, there is still a need for an anode active material to ensure that the anode active material, binder, and conductive material included in the anode are firmly bound and maintained.

According to one aspect, it is intended to provide a negative electrode active material included in a negative electrode, a negative electrode active material having improved binding force such as a binder, a negative electrode including the same, and a lithium secondary battery including the negative electrode.

According to one aspect,

a core comprising a carbon-based material;

a polycyclic compound represented by Formula 1 provided on the surface of the core;

A negative electrode active material containing a is provided.

<Formula 1>

L is a single bond, a substituted or unsubstituted C ₁ -C ₂₀ alkylene group, a substituted or unsubstituted C ₂ -C ₂₀ alkenylene group, a substituted or unsubstituted C _{2 -C 20 alkynylene group, and a substituted or unsubstituted C 2} -C ₂₀ alkynylene group. It is selected from a cyclic C ₆ -C ₂₀ aryl group;

R is a polar group or an ionic group,

m≥2, n≥1,

When n is 2 or more, two or more -L-R's may be the same as or different from each other.

According to another aspect, a negative electrode including a substrate and an anode active material layer formed on the substrate, wherein the anode active material layer includes the above-described anode active material and a binder, and the anode active material exists in a non-covalent bond state with the binder is provided.

According to another aspect, a negative electrode including the negative electrode active material; anode; And a lithium secondary battery including an electrolyte is provided.

In the negative electrode active material according to one aspect, deterioration of the negative electrode active material is prevented by binding a core including a carbon-based material and a polycyclic compound including a polar group and/or an ionic group through a non-covalent bond, and the polar group and / Or, since non-covalent bonding strength with other materials included in the current collector and the negative electrode, for example, a binder and a conductive material, is improved by the ionic group, the binding strength is improved, so the content of the binder can be reduced.

1 is a schematic diagram showing the structure of a lithium secondary battery according to an embodiment.
2 is a graph showing the results of Example 1 and Comparative Examples 1 and 2 binding force test.
3 is a graph showing the thickness increase rate of the negative electrode after charging the half cells of Example 5 and Comparative Examples 8 and 9 once.
4 is a graph showing the results of the binding force test of Example 2 and Comparative Examples 3 and 4;
5 is a graph showing the thickness increase rate of the negative electrode after charging the half cells of Example 6 and Comparative Examples 10 and 11 once.
6 is a graph showing the results of the binding force test of Example 3 and Comparative Examples 5 and 6;
7 is a graph showing the thickness increase rate of the negative electrode after charging the half cells of Example 7 and Comparative Examples 12 and 13 once.
8 is a graph showing the results of the binding force test of Example 4 and Comparative Examples 3 and 7;
9 is a graph showing the thickness increase rate of the negative electrode after charging the half cells of Example 8 and Comparative Examples 10 and 14 once.
<Description of symbols for main parts of drawings>
1: lithium battery 2: negative electrode
3: anode 4: separator
5: battery case 6: cap assembly

Since the present inventive concept described below can be applied with various transformations and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present creative idea to a specific embodiment, and should be understood to include all transformations, equivalents, or substitutes included in the technical scope of the present creative idea.

Terms used below are only used to describe specific embodiments, and are not intended to limit the present inventive idea. Singular expressions include plural expressions unless the context clearly dictates otherwise. Hereinafter, terms such as “comprise” or “have” are intended to indicate that there is a feature, number, step, operation, component, part, component, material, or combination thereof described in the specification, but one or the other It should be understood that the presence or addition of the above other features, numbers, steps, operations, components, parts, components, materials, or combinations thereof is not precluded. "/" used below may be interpreted as "and" or "or" depending on the situation.

Diameters, lengths, and thicknesses are shown enlarged or reduced in order to clearly represent various components, layers, and regions in the drawings. Like reference numerals have been assigned to like parts throughout the specification. Throughout the specification, when a part such as a layer, film, region, plate, etc. is said to be "on" or "above" another part, this includes not only the case directly on top of the other part, but also the case where there is another part in the middle thereof. . Throughout the specification, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. Terms are used only to distinguish one component from another. Although some of the components may be omitted in the drawings, this is to aid understanding of the features of the invention and is not intended to exclude the omitted components.

In this specification, the term "C ₁ -C ₁₀ alkyl group" means a straight or branched chain hydrocarbon monovalent group consisting of 1 to 10 carbon atoms, for example, a methyl group, an ethyl group, an isopropyl group, a propyl group, a butyl group etc. are included.

In this specification, the term "C ₁ -C ₂₀ alkylene group" means a divalent group having the same structure as a C ₁ -C ₂₀ alkyl group.

In this specification, the term “C ₂ -C ₂₀ alkenylene group” refers to a divalent hydrocarbon group including at least one carbon-carbon double bond among C ₂ -C ₂₀ alkyl groups.

In this specification, the term “C ₂ -C ₂₀ alkynylene group” refers to a divalent hydrocarbon group including at least one carbon-carbon triple bond among C ₂ -C ₂₀ alkyl groups.

In this specification, the term "C ₆ -C ₂₀ arylene group" means an aromatic hydrocarbon ring divalent group consisting of 6 to 20 carbon atoms. In this case, when it includes two or more hydrocarbon rings, the two or more hydrocarbon rings may be condensed with each other.

In the present specification, a substituted C ₁ -C ₁₀ alkyl group, a substituted C ₁ -C ₂₀ alkylene group, a substituted C ₂ -C ₂₀ alkenylene group, a substituted C ₂ -C ₂₀ alkynylene group, and a substituted C ₆ -C ₂₀ At least one of the substituents of the arylene group,

halogen, C ₁ -C ₁₀ alkyl group, C ₂ -C ₁₀ alkenyl group, C ₂ -C ₁₀ alkynyl group;

C ₆ -C ₂₀ arylene group; and

a _{C 6} -C ₂₀ arylene group _substituted with at least one of a C 1 -C ₁₀ alkyl group, a C ₂ -C ₁₀ alkenyl group, and a C ₂ -C 10 alkynyl group;

can be selected from.

Hereinafter, a negative electrode active material according to exemplary embodiments, a negative electrode including the same, and a lithium secondary battery including the negative electrode will be described in more detail.

An anode active material according to one aspect includes a core including a carbon-based material; A polycyclic compound represented by Formula 1 provided on the surface of the core; includes:

<Formula 1>

L is a single bond, a substituted or unsubstituted C ₁ -C ₂₀ alkylene group, a substituted or unsubstituted C ₂ -C ₂₀ alkenylene group, a substituted or unsubstituted C 2 -C 20 alkynylene group, and a substituted or unsubstituted C ₂ -C ₂₀ alkynylene group. selected from cyclic C ₆ -C ₂₀ arylene groups;

R is a polar group or an ionic group,

m≥2, n≥1,

When n is 2 or more, two or more -L-R's may be the same as or different from each other.

The anode active material is formed by disposing a polycyclic compound having a polar group and/or an ionic group on the surface of the core, so that the polar group and/or ionic group are adjacent to other anode active material slurry materials, such as binders, conductive materials, and other materials. Not only the binding force with the negative electrode active materials is improved, but also the binding force with the negative electrode current collector is improved. Therefore, as the materials included in the negative electrode are firmly bonded, the volume expansion of the negative electrode active material during charging is effectively suppressed, thereby having an advantageous effect of reducing the rate of increase in the thickness of the electrode. The decrease in the rate of increase in the thickness of the electrode reduces the size of the gap between the active materials according to the volume change of the negative electrode active material, and as a result, the deterioration of the active material due to the side reaction between the active material and the electrolyte is prevented.

The polycyclic compound may be bonded to the surface of the core through a non-covalent bond. Here, "non-covalent bond" is a bond by an interaction other than a covalent bond in which atoms or molecules bond in a way of sharing electrons, including electrostatic interaction, hydrogen bonding, van der Waals interaction, hydrophobic interaction, and the like. do.

The polycyclic moiety of the polycyclic compound and the surface of the core including the carbon-based material may be bonded through a π-π interaction. Here, "π-π interaction" is one of the non-covalent bonding interactions that occur when a π electron cloud existing in one molecule is adjacent to a π electron cloud of another molecule, and the static electricity of partial positive/negative charges formed by the distribution of electron clouds. Means the interaction that occurs through the thoraco-gravity. Having a hydrophobic carbon-based material or a carbon-based material on the outer surface by bonding the polycyclic moiety of the polycyclic polar group-containing compound and the surface of the core including the carbon-based material by π-π interaction. The surface of the core is modified with the ionic group moeity of the polycyclic compound. By such surface modification, the surface of the carbon-based material or the core having the carbon-based material on the outer surface becomes hydrophilic, and binding force is improved through enhanced non-covalent bonding interaction with a general binder including a hydrophilic group.

The polycyclic compound may be included in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total amount of the negative electrode active material.

For example, the polycyclic compound may be used in an amount of 0.01 to 4.5 parts by weight, 0.01 to 4.0 parts by weight, 0.01 to 3.5 parts by weight, 0.01 to 3.0 parts by weight, 0.01 to 2.5 parts by weight, or 0.01 to 2.0 parts by weight based on 100 parts by weight of the total amount of the negative electrode active material. 0.01 to 1.5 parts by weight, 0.01 to 1.0 parts by weight, 0.01 to 0.5 parts by weight, 0.01 to 0.45 parts by weight, 0.01 to 0.40 parts by weight, 0.01 to 0.35 parts by weight, 0.01 to 0.30 parts by weight, 0.01 to 0.25 parts by weight , 0.01 to 0.20 parts by weight, 0.01 to 0.15 parts by weight, or 0.01 to 0.10 parts by weight, but is not limited thereto, and an amount sufficient to obtain the desired binding force of the negative electrode active material may be selected.

The core may further include a metal alloyable with lithium and/or an oxide of a metal alloyable with lithium. When the core further includes a metal alloyable with lithium and/or an oxide of a metal alloyable with lithium, an anode active material having a higher capacity than an active material made of only a carbon-based material can be obtained.

For example, the metal alloyable with lithium is Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y ₁ alloy (where Y ₁ is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, or a transition metal) , rare earth elements, and any one or more elements selected from combinations thereof, but not including Si), Sn—Y ₂ alloy (wherein Y ₂ is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, or a transition metal) , rare earth elements, and any one or more elements selected from combinations thereof, but not including Sn), and the like. The elements Y ₁ and Y ₂ are each independently Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc , Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As , Sb, Bi, S, Se, or Te.

For example, the oxide of a metal alloyable with lithium may include silicon oxide represented by Formula 2 below, but is not limited thereto:

<Formula 2>

SiOx (0<x≤2)

According to one embodiment, the core may include a carbon-based material and/or an oxide of a metal alloyable with lithium, and the carbon-based material may be disposed on a surface of the oxide of a metal alloyable with lithium.

According to one embodiment, the core may include a metal alloyable with lithium coated with a carbon-based material. For example, the core may include silicon-carbon composite particles in which surfaces of silicon particles or silicon secondary particles formed by aggregation of silicon particles are coated with a carbon-based material.

According to another embodiment, the core may include an oxide of a metal alloyable with lithium coated with a carbon-based material. For example, the core may include a silicon oxide-carbon composite particle in which a surface of silicon oxide is coated with a carbon-based material.

According to another embodiment, the core may include a metal alloyable with lithium and an oxide of a metal alloyable with lithium, the surface of which is coated with a carbon-based material. For example, the core may include carbon-coated silicon-based composite particles in which surfaces of secondary silicon particles in which silicon particles and silicon oxide are mixed are coated with a carbon-based material.

According to another embodiment, the core may include a carbon-based material including a cavity in the center. For example, the core may include a carbon-based material including cavities such as carbon nanotubes and fullerenes.

According to another embodiment, the core may be made of only a carbon-based material. For example, the core may include natural graphite or artificial graphite.

The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as amorphous, plate, flake, spherical or fibrous natural graphite or artificial graphite, and the amorphous carbon may be soft carbon (low-temperature calcined carbon) or hard carbon carbon), mesophase pitch carbide, calcined coke, and the like.

According to one embodiment, the carbon-based material may include crystalline carbon. For example, the carbon-based material may be plate-shaped natural graphite or artificial graphite formed by condensation of benzene rings on the same plane. As a result, an anode active material having a structure in which a benzene ring in a carbon-based material and a polycyclic ionic group-containing compound are stacked on a carbon-based material by a π-π interaction of a polycyclic moiety in the compound is obtained. can lose Therefore, despite the introduction of the polycyclic ionic group-containing compound, a decrease in the conductivity of the carbon-based material is not caused, and intercalation and deintercalation of lithium ions are not hindered.

는 하기 화학식 2-1 내지 2-23으로부터 선택된 그룹일 수 있으나, 이에 한정되는 것은 아니며, 벤젠 고리가 m개 축합된 다양한 구조의 다환 방향족 고리가 선택될 수 있다.In Formula 1 above

may be a group selected from Chemical Formulas 2-1 to 2-23, but is not limited thereto, and polycyclic aromatic rings having various structures in which m benzene rings are condensed may be selected.

.

.

In Formula 1, L is

single bond;

a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, and a decylene group; and

Methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group substituted with one or more of methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, and decyl group group, a heptylene group, an octylene group, a nonylene group and a decylene group;

It may be selected from, but is not limited thereto.

According to one embodiment, in Formula 1, L is

a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group; and

a methylene group, an ethylene group, a propylene group, and a butylene group substituted with one or more of a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group;

It may be selected from, but is not limited thereto.

In Formula 1, R may be a polar group or an ionic group.

According to one embodiment, the ionic group may include a cationic group, an anionic group, or a combination thereof.

For example, the ionic group is -COO ^- , -SO ₃ ^- , -SO ₄ ^2- or -PO ₄ ^2- ; And NH ₃ ⁺ , NH ₂ R _a ⁺ , NHR _a R _b ⁺ , NR _a R _b R _c ⁺ , or PR _a R _b R _c ⁺ (R _a , R _b , R _c are each independently substituted or unsubstituted selected from C ₁ -C ₁₀ alkyl groups), but is not limited thereto.

For example, the polar group is -OH, -CHO -COOH, -SO ₃ H, -SO ₄ H, -PO ₄ H, -NH ₂ , -NHR _a or -NR _a R _b (R _a , R _b are independently selected from substituted or unsubstituted C ₁ -C ₁₀ alkyl groups), but is not limited thereto.

Here, the substituent of the substituted C ₁ -C ₁₀ alkyl group is, for example, a methyl group, an ethyl group, a propyl group, an iso-propyl group, a butyl group, a sec-butyl group, an iso-butyl group, and a tert-butyl group. can be selected from.

In Formula 1, when R is a polar group or an ionic group, through a π-π interaction, the surface of the anode active material modified with the polycyclic compound and the binder including a hydrophilic group are non-covalently bonded to each other. The binding force between the and the anode active material was improved.

In Formula 1, m≥4, and n may be 1 or 2. For example, when m is 4, n may be 1 or 2.

According to one embodiment, m is 4x, and n may be an integer selected from x to 2x (x = 1 or more integers). For example, when m is 8, n may be 2 to 4. When m and n satisfy the above ratio, the anode active material and other materials constituting the anode, such as a binder, a conductive material, and an anode current collector, have improved bonding strength, and the anode including the same has a reduced electrode expansion rate. have

An anode according to one aspect includes the anode active material described above.

An anode according to one aspect includes a substrate and an anode active material layer formed on the substrate, the anode active material layer includes the above-described anode active material, and a binder, and the anode active material may exist in a non-covalent bond state with the binder. there is.

For example, the non-covalent bonds may include electrostatic interactions, hydrogen bonds, van der Waals interactions, hydrophobic interactions, and combinations thereof.

The substrate may be an anode current collector. As the anode current collector, one selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a conductive metal-coated polymer substrate, and combinations thereof may be used.

According to one embodiment, the binding force between the negative electrode active material layer and the substrate may be 0.5 gf/mm or more.

A lithium secondary battery according to one aspect includes a negative electrode including the negative electrode active material described above; anode; contains electrolyte.

In the lithium secondary battery, the thickness increase rate of the negative electrode after one charge may be 50% or less. For example, the lithium secondary battery has an increase in the thickness of the negative electrode after one charge of less than 50%, less than 49%, less than 48%, less than 47%, less than 46%, less than 45%, less than 44%, less than 43%, 42% or less, 41% or less, 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, or 35% or less.

For example, the lithium secondary battery may be manufactured by the following method.

First, an anode is prepared.

For example, a cathode active material composition in which a cathode active material, a conductive material, a binder, and a solvent are mixed is prepared. The positive electrode active material composition is directly coated on a metal current collector to prepare a positive electrode plate. Alternatively, the positive electrode active material composition may be cast on a separate support, and then the film separated from the support may be laminated on a metal current collector to manufacture a positive electrode plate. The anode is not limited to the forms listed above and may have forms other than the above forms.

The cathode active material is a lithium-containing metal oxide, and any material commonly used in the art may be used without limitation. For example, one or more types of complex oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used. Another example is Li _a A _1-b B ¹ _b D ¹ ₂ (wherein 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li _a E _1-b B ¹ _b O _2-c D ¹ _c (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE _2-b B ¹ _b O _4-c D ¹ _c (wherein 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li _a Ni _1-bc Co _b B ¹ _c D ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li _a Ni _1-bc Co _{b B} ¹ _c O _2-α F ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Co _{b B} ¹ _c O _2-α F ¹ ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B ¹ _c D ¹ _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li _a Ni _1-bc Mn _b B ¹ _c O _2-α F1 _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B ¹ _c O _2-α F ¹ ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _b E _c G _d O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li _a NiG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a CoG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a MnG _b O ₂ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a Mn ₂ G _b O ₄ (wherein 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiI ¹ O ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); A compound represented by any of the chemical formulas of LiFePO ₄ may be used:

In the above formula, A is Ni, Co, Mn, or a combination thereof; B ¹ is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D ¹ is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F ¹ is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or combinations thereof.

For example, LiCoO ₂ , LiMn _x O _2x (x=1, 2), LiNi _1-x Mn _x O _2x (0<x<1), LiNi _1-xy Co _x Mn _y O ₂ (0≤x≤ 0.5, 0≤y≤0.5), LiFePO ₄ and the like.

Of course, one having a coating layer on the surface of the compound may be used, or a mixture of the compound and a compound having a coating layer may be used. The coating layer may include a coating element compound of an oxide, a hydroxide, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, or a hydroxycarbonate of a coating element. Compounds constituting these coating layers may be amorphous or crystalline. As the coating element included in the coating layer, Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof may be used. In the process of forming the coating layer, any coating method may be used as long as the compound can be coated in a method (eg, spray coating, dipping method, etc.) that does not adversely affect the physical properties of the positive electrode active material by using these elements. Since it is a content that can be well understood by those skilled in the art, a detailed description thereof will be omitted.

As the conductive material, carbon black, graphite particles, etc. may be used, but are not limited thereto, and any material that can be used as a conductive material in the art may be used.

Examples of the binder include vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene and mixtures thereof, or styrene butadiene rubber-based polymers. This may be used, but is not limited thereto, and any binder that can be used in the art may be used.

N-methylpyrrolidone, acetone, or water may be used as the solvent, but it is not limited thereto, and any solvent that can be used in the art may be used.

The contents of the positive electrode active material, conductive material, binder, and solvent are levels commonly used in lithium batteries. At least one of the conductive material, the binder, and the solvent may be omitted depending on the use and configuration of the lithium battery.

Next, the cathode is prepared.

For example, an anode active material composition is prepared by mixing the above-described anode active material, conductive material, binder, and solvent. The negative electrode active material composition is directly coated on a metal current collector and dried to prepare a negative electrode plate. Alternatively, after the negative electrode active material composition is cast on a separate support, a film separated from the support is laminated on a metal current collector to manufacture a negative electrode plate.

The content of the binder may be 1.0 to 10 parts by weight based on 100 parts by weight of the entire negative electrode active material layer. As the binding force of the negative electrode active material layer to the current collector is improved, the content of the binder may be reduced. In addition, as the binder content in the negative electrode active material layer decreases, the resistance of the electrode decreases and the capacity density increases, thereby improving battery performance.

The contents of the conductive material and the solvent are at levels commonly used in lithium batteries. At least one of the conductive material, the binder, and the solvent may be omitted depending on the use and configuration of the lithium battery.

Next, a separator to be inserted between the positive electrode and the negative electrode is prepared.

Any of the separators commonly used in lithium batteries may be used. An electrolyte having low resistance to ion migration and excellent ability to absorb the electrolyte may be used. For example, it may be selected from glass fibers, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or combinations thereof, and may be in the form of non-woven fabric or woven fabric. For example, a rollable separator such as polyethylene or polypropylene may be used in a lithium ion battery, and a separator having excellent organic electrolyte impregnating ability may be used in a lithium ion polymer battery. For example, the separator may be manufactured according to the following method.

A separator composition is prepared by mixing a polymer resin, a filler, and a solvent. A separator may be formed by directly coating and drying the separator composition on an electrode. Alternatively, after the separator composition is cast and dried on a support, a separator film separated from the support may be laminated on an electrode to form a separator.

The polymer resin used to manufacture the separator is not particularly limited, and all materials used for the binder of the electrode plate may be used. For example, vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or mixtures thereof may be used.

Next, the electrolyte is prepared.

For example, the electrolyte may be an organic electrolyte. Also, the electrolyte may be solid. For example, it may be boron oxide, lithium oxynitride, etc., but is not limited thereto, and any solid electrolyte that can be used in the art can be used. The solid electrolyte may be formed on the negative electrode by a method such as sputtering.

For example, the organic electrolyte may be prepared by dissolving a lithium salt in an organic solvent.

The organic solvent may be used as long as it can be used as an organic solvent in the art. For example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate , benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide , dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or mixtures thereof.

The lithium salt may also be used as long as it can be used as a lithium salt in the art. For example, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiAlO ₂ , LiAlCl ₄ , LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ) (provided that x and y are natural numbers), LiCl, LiI, or mixtures thereof.

As shown in FIG. 1 , the lithium battery 1 includes a positive electrode 3 , a negative electrode 2 and a separator 4 . The positive electrode 3 , the negative electrode 2 and the separator 4 are wound or folded and accommodated in the battery case 5 . Subsequently, an organic electrolyte solution is injected into the battery case 5 and sealed with a cap assembly 6 to complete the lithium battery 1 . The battery case 5 may be cylindrical, prismatic, or thin film. For example, the lithium battery 1 may be a thin film battery. The lithium battery 1 may be a lithium ion battery.

A battery structure may be formed by placing a separator between the positive electrode and the negative electrode. After the battery structure is stacked in a bi-cell structure, impregnated with an organic electrolyte, and the obtained product is accommodated in a pouch and sealed, a lithium ion polymer battery is completed.

In addition, a plurality of the battery structures are stacked to form a battery pack, and such a battery pack can be used in all devices requiring high capacity and high output. For example, it can be used for laptops, smartphones, electric vehicles, and the like.

In addition, since the lithium battery has excellent lifespan characteristics and high rate characteristics, it can be used in electric vehicles (EVs). For example, it can be used for hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring large amounts of power storage. For example, it can be used for electric bicycles, power tools, and the like.

The present invention is explained in more detail through the following Examples and Comparative Examples. However, the examples are for exemplifying the present invention, and the scope of the present invention is not limited only thereto.

Preparation Example 1 (-NH ₃ ⁺ Preparation of pyrene derivatives containing)

After mixing 0.05 g of 1-pyrenemethylamine hydrochloride and 15 mL of distilled water, the mixture was heated to 40 ° C and stirred for one day to obtain a surface modification solution containing a pyrene derivative represented by the following formula .

Preparation Example 2 (-COO ^- Preparation of pyrene derivatives containing)

After mixing 0.1 g of 1-pyrene butyric acid and 10 mL of distilled water, 1 equivalent of 1-pyrene butyric acid was added with lithium hydroxide monohydrate and then heated at 40°C. The mixture was heated and stirred for one day to obtain a surface modification solution containing a pyrene derivative represented by the following chemical formula.

Production Example 3 (Preparation of monocyclic ionic group-containing compound)

After mixing 4-phenylbutyric acid (0.1 g of 4-Phenyl butyric acid 0 and 10 mL of distilled water), lithium hydroxide monohydrate of 1 equivalent of 4-phenylbutyric acid was added and heated at 40 ° C for one day. while stirring to obtain a surface-modified solution containing a monocyclic ionic group-containing compound represented by the following formula.

Production Example 4 (Preparation of pyrene derivative containing -OH)

0.1 M 1-pyrenemethanol (sigma-Aldrich) was dissolved in DMSO to obtain a surface modification solution containing a polycyclic polar group-containing compound represented by the following formula.

Production Example 5 (Preparation of Monocyclic Compound Containing -OH)

By dissolving 0.1 M phenylmethanol in DMSO, a surface modification solution containing a monocyclic polar group-containing compound represented by the following formula was obtained.

(manufacture of cathode)

Examples 1 and 2, and Comparative Examples 2 and 4

In order to prepare a negative electrode, as shown in Table 1 below, 1 g of the core material and 0.1 mL of the surface modifier prepared in Preparation Example 2 or 3 were put into a sinky mixer and mixed. Subsequently, a binder obtained by mixing styrene butadiene rubber (SBR) and carboxymethylcellulose (CMC) in a weight ratio of 1: 1 was added in the weight % shown in Table 1 below with respect to the negative electrode active material slurry, and distilled water was added to the sinky mixer After adding and mixing, a negative electrode active material slurry was obtained. The slurry was cast on a copper current collector and dried for 10 minutes at 110° C. under atmospheric pressure conditions to prepare a negative electrode.

Examples 3 to 4 and Comparative Examples 6 to 7

As shown in Table 1 below, 1 g of the core material and 10 mL of the surface modifier prepared in Preparation Example 4 or 5 were mixed and stirred at room temperature for two days. Thereafter, the obtained mixture was filtered, and the obtained active material was dried at 70° C. under normal pressure for two days to obtain an anode active material.

A binder obtained by mixing 1 g of the obtained anode active material with styrene butadiene rubber (SBR) and carboxymethylcellulose (CMC) in a weight ratio of 1:1 was put into a sinky mixer and mixed to obtain a slurry of the anode active material. The slurry was cast on a copper current collector and dried for 10 minutes at 110° C. under atmospheric pressure conditions to prepare a negative electrode.

Comparative Examples 1, 3 and 5

To prepare the negative electrode, a binder obtained by mixing 1 g of the core material shown in Table 1 with styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) in a weight ratio of 1: 1 was prepared by weight% shown in Table 1 below. was added to obtain a negative active material slurry. The slurry was cast on a copper current collector and dried for 10 minutes at 110° C. under atmospheric pressure conditions to prepare a negative electrode.

core surface modifier Binder content ratio
(weight%) Example 1 black smoke Preparation Example 2 5 Example 2 Carbon coated SiO Preparation Example 2 10 Example 3 black smoke Production Example 4 2 Example 4 Carbon coated SiO Production Example 4 10 Comparative Example 1 black smoke - 5 Comparative Example 2 black smoke Preparation Example 3 5 Comparative Example 3 Carbon coated SiO - 10 Comparative Example 4 Carbon coated SiO Preparation Example 3 10 Comparative Example 5 black smoke - 2 Comparative Example 6 black smoke Preparation Example 5 2 Comparative Example 7 Carbon coated SiO Preparation Example 5 10

(coin cell production)

Examples 5 to 8 and Comparative Examples 8 to 13

Lithium foil was used as the negative electrode and counter electrode prepared in Examples 1 to 4 and Comparative Examples 1 to 7, and a porous polyethylene film was placed as a separator between the negative electrode and the counter electrode, and an organic electrolyte solution (1M LiPF ₆ EC/DEC = 1/ 1 (v/v) FEC (10 wt%) was injected to fabricate a negative half-cell.

Evaluation Example 1: Evaluation of binding force

The negative electrodes prepared in Examples 1 to 4 and Comparative Examples 1 to 7 were cut into 30 mm in width and 60 mm or more in length. The cathode sample is attached to a glass substrate having a width of 25 mm and a length of 30 mm with double-sided tape attached thereto, and one end of the glass substrate and one end of the cathode sample are fixed to the universal tester equipment at 180 degrees. The displacement was set to 0 ~ 30 mm, and the intensity of force applied when the anode sample adhered to the glass substrate was separated was quantitatively measured. The results are shown in Figures 2, 4, 6, and 8.

Referring to FIG. 2, a negative electrode (Example 1) including a carbon-based negative electrode active material surface-modified by a pyrene derivative having an electric charge is a negative electrode (Comparative Example 1) including a carbon-based negative electrode active material that is not surface-modified, and The maximum binding force was increased by about 50% or more compared to the negative electrode (Comparative Example 2) including the carbon-based negative electrode active material surface-modified with a phenyl derivative. The intensity of the binding force generally means the force while the graph remains relatively stable after a distance of 5 mm.

Referring to FIG. 4, a negative electrode (Example 2) including a silicon-based negative electrode active material surface-modified by a pyrene derivative having an electric charge is a negative electrode (Comparative Example 3) including a silicon-based negative electrode active material that is not surface-modified and a phenyl derivative The maximum binding force was increased by about 15% or more compared to the negative electrode (Comparative Example 4) including the silicon-based negative electrode active material surface-modified by

Referring to FIG. 6, a negative electrode (Example 3) including a carbon-based negative electrode active material surface-modified by a pyrene derivative having a polar group is a negative electrode (Comparative Example 5) including a carbon-based negative electrode active material that is not surface-modified and a phenyl The maximum binding force was increased by about 30% or more compared to the negative electrode (Comparative Example 6) including the carbon-based negative electrode active material surface-modified by the derivative.

Referring to FIG. 8, the negative electrode (Example 4) including a silicon-based negative electrode active material surface-modified by a pyrene derivative having a polar group is a negative electrode (Comparative Example 3) including a silicon-based negative electrode active material that is not surface-modified and a phenyl derivative The maximum binding force increased by about 30% or more compared to the negative electrode (Comparative Example 7) including the silicon-based negative electrode active material surface-modified by

Evaluation Example 2: Evaluation of electrode expansion rate

After charging Examples 5 to 8 and Comparative Examples 8 and 14 once at a current density of 0.2 C, the negative electrode was separated, and the change in thickness before and after charging was measured. The rate of increase in electrode thickness is shown in FIGS. 3, 5, 7 and 9.

Referring to FIG. 3, the negative electrode (Example 5) including the carbon-based negative electrode active material surface-modified by a pyrene derivative having an electric charge is approximately The electrode thickness change rate was reduced by 5%, and the electrode thickness change rate was reduced by about 10% compared to the negative electrode (Comparative Example 9) including the negative electrode active material surface-modified by phCOO-.

Referring to FIG. 5, the negative electrode (Example 6) including the silicon-based negative electrode active material surface-modified by a pyrene derivative having an electric charge is about 15% smaller than the negative electrode (Comparative Example 10) including the silicon-based negative electrode active material that is not surface-modified. The electrode thickness change rate was reduced, and the electrode thickness change rate was reduced by about 17% compared to the negative electrode (Comparative Example 11) including the silicon-based negative electrode active material surface-modified by phCOO-.

Referring to FIG. 7, the negative electrode including the carbon-based negative electrode active material surface-modified by a pyrene derivative having a polar group (Example 7) has about 5 % decreased electrode thickness change rate, and about 4% decreased electrode thickness change rate compared to the negative electrode (Comparative Example 13) including the carbon-based negative electrode active material surface-modified by phenylmethanol.

Referring to FIG. 9, the negative electrode (Example 8) including the silicon-based negative electrode active material surface-modified by a pyrene derivative having an electric charge is about 17% lower than the negative electrode (Comparative Example 10) including the silicon-based negative electrode active material that is not surface-modified. The electrode thickness change rate was reduced, and the electrode thickness change rate was reduced by about 15% compared to the negative electrode (Comparative Example 14) including the negative electrode active material surface-modified by phenylmethanol.

Above, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain it, and the protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope thereof It should be construed as being included in the scope of the present invention.

Claims (18)

a core comprising a carbon-based material;
a polycyclic compound represented by Formula 1 provided on the surface of the core;
Anode active material containing:
<Formula 1>

L is a substituted or unsubstituted C ₁ -C ₂₀ alkylene group, a substituted or unsubstituted C ₂ -C ₂₀ alkenylene group, a substituted or unsubstituted C 2 -C ₂₀ alkynylene group, and a substituted or unsubstituted C ₂ -C 20 alkenylene group. ₆ -C ₂₀ It is selected from aryl groups,
R is a polar group or an ionic group,
m≥2, n≥1,
When n is 2 or more, two or more -LRs may be the same as or different from each other. According to claim 1,
The polycyclic compound is bonded to the surface of the core by a non-covalent bond, the negative electrode active material. According to claim 1,
A negative electrode active material wherein the polycyclic moeity of the polycyclic compound and the surface of the core are bonded by π-π interaction. According to claim 1,
The negative electrode active material includes the polycyclic compound in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total amount of the negative electrode active material. According to claim 1,
The core further comprises an oxide of a metal alloyable with lithium and/or a metal alloyable with lithium. According to claim 5
The metal alloyable with lithium is selected from Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y ₁ alloy, and Sn-Y 2 alloy,
In this case, Y ₁ is any one or more elements selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, but does not include Si, and Y ₂ is alkali An anode active material comprising at least one element selected from among metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, but not including Sn. According to claim 5,
The oxide of the metal alloyable with lithium is silicon oxide represented by the following formula (2), a negative electrode active material:
<Formula 2>
SiOx (0<x≤2) According to claim 7,
wherein the core includes a carbon-based material and/or an oxide of a metal alloyable with lithium, and the carbon-based material is disposed on a surface of the oxide of a metal alloyable with lithium. According to claim 1,
The carbon-based material is crystalline carbon, amorphous carbon or a mixture thereof, negative electrode active material. According to claim 1,
In Formula 1 above

Is a group selected from the following formulas 2-1 to 2-23, negative electrode active material:

. According to claim 1,
L is
a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, and a decylene group; and
Methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group substituted with one or more of methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, and decyl group group, a heptylene group, an octylene group, a nonylene group and a decylene group;
A cathode active material selected from. According to claim 1,
The ionic group includes a cationic group, an anionic group, or a combination thereof. According to claim 1,
R is
-OH, -CHO, -COOH, -SO ₃ H, -SO ₄ H, -PO ₄ H, -NH ₂ , -NHR _a , -NR _a R _b ;
^-COO- , -SO ₃ ^- , -SO ₄ ^2- or -PO ₄ ^2- ; and
-NH ₃ ⁺ , -NH ₂ R _a ⁺ , -NHR _a R _b ⁺ , -NR _a R _b R _c ⁺ , -PR _a R _b R _c ⁺ ;
is selected from
Here, R _a , R _b , R _c are each independently selected from a substituted or unsubstituted C ₁ -C ₁₀ alkyl group, the negative electrode active material. According to claim 1,
m≥4, and n is 1 or 2, the negative electrode active material. A substrate, and a negative electrode active material layer formed on the substrate,
The negative active material layer includes the negative active material according to any one of claims 1 to 14 and a binder,
The negative electrode active material is a negative electrode that exists in a non-covalent bond with the binder. According to claim 15,
The negative electrode active material layer and the binding force between the substrate is 0.5 gf / mm or more. A negative electrode comprising the negative electrode active material according to any one of claims 1 to 14;
anode; and
electrolyte;
A lithium secondary battery comprising a. According to claim 17,
The lithium secondary battery, wherein the thickness increase rate of the negative electrode after one charge of the lithium secondary battery is 40% or less compared to before charging.

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