KR102651545B1 - Composite membrane for Lithium battery, a cathode for lithium battery, and lithium battery comprising the same - Google Patents

Abstract

A composite membrane for a lithium battery containing a copolymer containing a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2), a positive electrode for a lithium battery, and a lithium battery containing the same are provided.
[Formula 1] [Formula 2]

In Formula 1, Ar ₁ , R ₁ , R ₂ , R ₃ , A, , Y ^- are as defined in the detailed description, and in Formula 2, R ₄ to R ₇ , a, m, and n are as defined in the detailed description.

Description

Composite membrane for lithium battery, anode for lithium battery, and lithium battery including the same {Composite membrane for Lithium battery, a cathode for lithium battery, and lithium battery comprising the same}

It relates to composite membranes for lithium batteries, anodes for lithium batteries, and lithium batteries containing the same.

In response to the explosive growth of the market for reusable energy storage devices that can be applied to electric vehicles and portable electronic devices, the demand for high capacity characteristics and improved stability for lithium batteries, the most representative energy storage device, is growing. . In response to these demands, various studies are being conducted to apply lithium metal electrodes as negative electrodes for lithium batteries to increase charge storage and utilize them at high voltages. Lithium metal electrodes have a very large electrical capacity per unit mass. In the lithium metal electrode, a dendrite structure is formed on the surface of the lithium metal during the insertion/release process of lithium ions, which may cause a short circuit between the anode and the cathode. Therefore, a method that can suppress dendrite formation on the surface of lithium metal is required.

One aspect is to provide a novel composite membrane for lithium batteries.

Another aspect is to provide a lithium battery including a composite membrane for lithium batteries.

Another aspect is providing an anode for lithium batteries.

According to one aspect, a composite membrane for a lithium battery containing a copolymer containing a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2) is provided.

[Formula 1]

In Formula 1, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group,

R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,

A simply represents a chemical bond, or an unsubstituted or substituted C1-C30 alkylene group, an unsubstituted or substituted C6-C30 arylene group, an unsubstituted or substituted C3-C30 heteroarylene group, or an unsubstituted or substituted It is a C4-C30 cycloalkylene group, or an unsubstituted or substituted C3-C30 heterocycloalkylene group,

is a 3- to 31-membered ring containing 2 to 30 carbon atoms,

X is S, N, N(R) or P(R ^' ),

R and R ^' are independently of each other hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 heteroalkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C7-C30 arylalkyl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C4-C30 heteroarylalkyl group, unsubstituted or substituted C3-C30 cycloalkyl group, unsubstituted or substituted C2-C30 alkenyl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or A substituted C3-C30 heterocycloalkyl group or an unsubstituted or substituted C3-C30 alkynyl group,

Y ^- is an anion,

[Formula 2]

In Formula 2, R ₄ , R ₅ , and R ₆ are independently hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3 -C30 is a heteroaryl group,

R ₇ is hydrogen, an unsubstituted or substituted C1-C20 alkyl group, or an unsubstituted or substituted C6-C20 aryl group,

a is an integer from 1 to 10,

In Formulas 1 and 2, m and n are the mole fractions of the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2, respectively, and their sum is 1, which are greater than 0 and less than 1, respectively.

Anode according to one side and the other; A lithium battery including a negative electrode and the above-described composite film interposed between the positive electrode and the negative electrode is provided.

According to another aspect, a positive electrode for a lithium battery is provided, which includes a positive electrode active material and a copolymer including a first repeating unit represented by Formula 1 below and a second repeating unit represented by Formula 2 below.

[Formula 1]

In Formula 1, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group,

R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,

A simply represents a chemical bond, or an unsubstituted or substituted C1-C30 alkylene group, an unsubstituted or substituted C6-C30 arylene group, an unsubstituted or substituted C3-C30 heteroarylene group, or an unsubstituted or substituted It is a C4-C30 cycloalkylene group, or an unsubstituted or substituted C3-C30 heterocycloalkylene group,

is a 3- to 31-membered ring containing 2 to 30 carbon atoms,

X is S, N, N(R) or P(R ^' ),

R and R ^' are independently of each other hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 heteroalkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C7-C30 arylalkyl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C4-C30 heteroarylalkyl group, unsubstituted or substituted C3-C30 cycloalkyl group, unsubstituted or substituted C2-C30 alkenyl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or A substituted C3-C30 heterocycloalkyl group or an unsubstituted or substituted C3-C30 alkynyl group,

Y ^- is an anion,

[Formula 2]

In Formula 2, R ₄ , R ₅ , and R ₆ are independently hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3 -C30 is a heteroaryl group,

R ₇ is hydrogen, an unsubstituted or substituted C1-C20 alkyl group,

Or an unsubstituted or substituted C6-C20 aryl group,

a is an integer from 1 to 10,

In Formulas 1 and 2, m and n are the mole fractions of the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2, respectively, and their sum is 1, which are greater than 0 and less than 1, respectively.

According to one aspect, by employing a negative electrode containing a new random copolymer, the formation of dendrites is suppressed on the negative electrode surface of the lithium battery, and the electrochemical stability, high rate characteristics, and lifespan characteristics of the lithium battery are improved.

Figure 1 schematically shows the composition of a copolymer according to one embodiment.
Figure 2 is an FT-IR spectrum of the random copolymer prepared according to Preparation Example 1.
Figure 3a is an NMR analysis spectrum for the random copolymer of Formula 6a obtained according to Preparation Example 1.
Figure 3b is a 2D DOSY (diffusion ordered spectroscopy) NMR spectrum of the random copolymer of Formula 6a obtained according to Preparation Example 1.
Figures 4a and 4b are cyclic voltammetry measurement results of the cathode manufactured according to Example 1.
Figure 5a shows the electrochemical impedance spectrum (EIS) analysis results for lithium batteries manufactured according to Example 1, Comparative Example 2, and Comparative Example 3.
Figure 5b shows charge transfer resistance characteristics for lithium batteries manufactured according to Example 1 and Comparative Examples 2 and 3.
Figure 6a shows lithium ion conductivity in lithium batteries manufactured according to Example 1, Comparative Example 1, and Comparative Example 3.
Figure 6b shows lithium ion mobility characteristics in lithium batteries manufactured according to Example 1, Comparative Example 1, and Comparative Example 3.
Figure 6c shows the lithium ion availability in lithium batteries manufactured according to Example 1, Comparative Example 1, and Comparative Example 3.
Figure 7a shows the electrochemical stability measurement results of the Li/Li symmetric cell manufactured according to Example 1.
Figure 7b shows the electrochemical stability measurement results of the Li/Li symmetric cell manufactured according to Comparative Example 2.
Figure 8a shows the lifespan characteristics of lithium batteries manufactured according to Example 4 and Comparative Example 4.
Figure 8b shows the potential change according to capacity in the lithium battery manufactured according to Example 4 and Comparative Example 4.
Figure 9 is a schematic diagram of a lithium battery according to an embodiment.

Hereinafter, a composite membrane for a lithium battery, an anode for a lithium battery, and a lithium battery including the same according to exemplary embodiments will be described in more detail.

A composite membrane for a lithium battery according to one embodiment contains a copolymer including a first repeating unit represented by Formula 1 below and a second repeating unit represented by Formula 2 below.

[Formula 1]

In Formula 1, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group, and R ₁ , R ₂ and R ₃ are hydrogen or unsubstituted regardless of each other. is a substituted or unsubstituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl group, and A simply represents a chemical bond or is an unsubstituted or substituted group. C1-C30 alkylene group, unsubstituted or substituted C6-C30 arylene group, unsubstituted or substituted C3-C30 heteroarylene group, unsubstituted or substituted C4-C30 cycloalkylene group, or unsubstituted or substituted It is a C3-C30 heterocycloalkylene group,

is a 3- to 31- ^membered ring containing 2 ^to 30 carbon atoms, Unsubstituted or substituted C1-C30 alkyl group, unsubstituted or substituted C1-C30 heteroalkyl group, unsubstituted or substituted C1-C30 alkoxy group, unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C7-C30 arylalkyl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C4-C30 heteroarylalkyl group, unsubstituted Unsubstituted or substituted C3-C30 cycloalkyl group, unsubstituted or substituted C2-C30 alkenyl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or substituted C3-C30 heterocycloalkyl group or unsubstituted It is a ringed or substituted C3-C30 alkynyl group, Y ^- is an anion,

[Formula 2]

In Formula 2, R ₄ , R ₅ , and R ₆ are independently hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3 -C30 is a heteroaryl group,

R ₇ is hydrogen, an unsubstituted or substituted C1-C20 alkyl group,

Or an unsubstituted or substituted C6-C20 aryl group,

a is an integer from 1 to 10,

In Formulas 1 and 2, m and n are the mole fractions of the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2, respectively, and their sum is 1, which are greater than 0 and less than 1, respectively.

The 3- to 31-membered ring containing 2 to 30 carbon atoms may be a saturated or unsaturated ring.

In Formula 1, Ar ₁ is one selected from the group consisting of a phenylene group, biphenylene group, naphthalenylene group, phenanthrenylene group, triphenylenylene group, anthracenylene group, fluorenylene group, and carbazolenylene group.

In Formula 1, Ar ₁ may be one selected from the group represented by Formula 3 below.

[Formula 3]

In Formula 3, * represents a binding region, and R ₁₁ to R ₁₉ are independently hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or It is a substituted C3-C30 heteroaryl group.

In the repeating unit of Formula 1, Ar1 is an arylene or heteroarylene group as described above. A copolymer having a repeating unit of Formula 1 having such an arylene group and a heteroarylene group has superior mechanical properties due to the π-π interaction of the arylene group or heteroarylene group described above. In Formula 1, when Ar ₁ is an aliphatic group such as an alkylene group or a divalent aliphatic ring, mechanical properties are significantly reduced compared to when Ar ₁ is an arylene group or heteroarylene group.

A lithium battery using a lithium metal electrode as a negative electrode can theoretically provide a high energy source, but not only does the liquid electrolyte react with moisture and oxygen to cause an exothermic reaction, but its thermal stability is lowered compared to graphite or carbon-based negative electrodes. In addition, the reactivity between the existing liquid electrolyte and the lithium metal electrode is very high, which causes the formation of an irreversible layer, which reduces the cycle characteristics of the lithium battery. To solve this problem, a lithium ion conductive polymer electrolyte is applied on top of the lithium metal electrode. It is common to use an ether-based electrolyte such as polyethylene oxide electrolyte as a lithium ion conductive polymer electrolyte. However, these ether-based electrolytes have relatively low lithium ion mobility compared to liquid electrolytes and their mechanical properties are not sufficient, so electrochemical performance may be reduced.

When the temperature of a lithium battery is raised, it is difficult for the ether-based electrolyte to maintain the form of a free-standing film, which may further deteriorate its mechanical properties and cause a short circuit. Additionally, the cycle characteristics of the lithium battery may deteriorate due to the formation and growth of lithium dendrites on the surface of the lithium negative electrode.

Accordingly, the present inventors provide a novel composite membrane that can improve electrochemical stability by suppressing side reactions with the lithium cathode. This composite membrane can be used as a protective film and electrolyte for a lithium negative electrode, or as a protective film and electrolyte for a lithium negative electrode.

According to one embodiment, a composite membrane for a lithium battery includes a first repeating unit having a polymerized ionic liquid (PIL) that has excellent lithium ion mobility and is electrochemically very stable, and a lithium ion conductive second repeating unit. Contains copolymers. The second repeating unit is a polyoxyethylene methacrylate (POEM) repeating unit. The copolymer can improve the electrochemical properties of a lithium battery by improving the low mechanical properties of the second repeating unit.

Figure 1 schematically shows the composition of a copolymer including a first repeating unit (PIL) represented by the following formula (1) and a second repeating unit (POEM) represented by the following formula (2) constituting a composite membrane for a lithium battery according to an embodiment. It is shown.

The first repeating unit of the copolymer has a group that provides structural rigidity and inhibits lithium dendrite growth, and the second repeating unit of the copolymer has a POEM group, which is a lithium ion conductive group. As shown in Figure 1, a copolymer having a first repeating unit and a second repeating unit may be a heterogeneous polymer containing a first repeating unit (PIL) and an ion-conducting second repeating unit (POEM). By having this non-homogeneous state, the effect of suppressing lithium dendrite growth is better than when using a polymer in a homogenized state.

As used herein, the term “heterogeneous polymer” refers to a polymer in which the first repeating unit (PIL) and the ion-conducting second repeating unit (POEM) exist irregularly or non-uniformly, as shown in FIG. 1.

The copolymer may be a random copolymer or a block copolymer.

Random copolymers contain first repeating units (PIL) and second repeating units (POEM) in a non-homogenized state. In a random copolymer, the first repeating unit and the second repeating unit exist in a non-homogenized state, and the interaction between the first repeating units is reduced compared to the block copolymer, so that the first repeating unit moves to the lithium region on the surface of the lithium negative electrode. This makes it easier to block the area around the lithium dendrite. As a result, it provides a uniform charge delocalization effect throughout the copolymer, so that dendrite formation due to local increase of lithium ions on the surface of lithium metal can be more effectively suppressed.

Additionally, random copolymers are easier to synthesize and less expensive to manufacture compared to block copolymers. In addition, random copolymers can exhibit similar physical properties across the polymer backbone compared to block copolymers.

For example, the block copolymer containing the above-described first and second repeating units has a local presence of the first repeating unit and the second repeating unit that does not contain an ionic liquid moiety compared to the random copolymer. Therefore, it may be difficult to uniformly suppress the growth of lithium dendrites on the surface of the lithium cathode. In addition, block copolymers are prone to localization of charges in the polymer block portion composed of a second repeating unit that does not contain an ionic liquid moiety, resulting in dendrites caused by local reduction of lithium ions on the surface of lithium metal. It can be difficult to effectively inhibit growth. In addition, self-interaction between the first repeating units may make it relatively difficult to move to the lithium dendrite position compared to a random copolymer, thereby reducing the opportunity to block the lithium dendrite. Therefore, the lithium dendrite inhibition effect of random copolymers may be improved more than that of block copolymers.

The composite membrane according to one embodiment has excellent mechanical properties and includes a copolymer with an ionic liquid unit capable of reducing lithium metal dendrites, has excellent mechanical properties at high temperatures compared to a POEM-containing membrane, and contains a large amount of lithium salt. It can be supported. Therefore, the ability to move lithium ions is further improved, making it possible to manufacture a lithium battery with improved cycle characteristics.

The composite membrane for lithium batteries can be used as a cathode protective film for lithium batteries or as an electrolyte. The composite membrane can be used as a cathode protective membrane and electrolyte.

In formula 1 may be an imidazole ring, which is an aliphatic ring or a nitrogen-containing aromatic ring.

may be an aliphatic ring. The copolymer contains By forming an aliphatic ring, it is stable in a wider voltage range compared to ionic liquid polymers containing an aromatic ring, and thus can provide a wider electrochemical window. For example, it can provide a wider reduction potential for lithium metal. For example, random copolymers can be electrochemically stable even in the negative voltage range with respect to lithium metal. As used herein, “electrochemically stable” means that the current due to oxidation or reduction of the copolymer itself is less than 1/2 of the current due to oxidation/reduction of lithium.

The aliphatic ring contained in the copolymer is not particularly limited, and any ring that can function as a moiety corresponding to a cation of an ionic liquid in the art is possible.

of formula 1 may be selected from the group represented by Formula 4 and the group represented by Formula 4a.

[Formula 4]

In Formula 4, Z is S, N or P, and R ₁₁ to R ₂₅ are independently hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy group, or an unsubstituted group. Unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C3-C30 heteroaryloxy group, It is an unsubstituted or substituted C4-C30 cycloalkyl group or an unsubstituted or substituted C3-C30 heterocycloalkyl group,

However, if Z is S, R ₁₁ is absent.

[Formula 4a]

In Formula 4a, R ₂₂ to R ₂₆ are defined the same as R ₁₁ to R ₂₅ in Formula 4, and Z is N.

of formula 1 is selected from the group represented by the following formula (5),

Y ^- in ^Formula 1 is BF ₄ ^- , PF ₆ ^- , AsF ₆ -, SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , CH ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , (FSO ₂ ) ₂ N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , and -(O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- selected from It may be one or more anions.

[Formula 5]

In Formula 5, R ₂₀ to R ₂₈ are each independently hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, Unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or substituted C4-C30 cyclo It is an alkyl group or an unsubstituted or substituted C3-C30 heterocycloalkyl group.

The composite membrane contains lithium salt. The content of the lithium salt is 1 to 90 parts by weight, for example, 20 to 60 parts by weight, based on 100 parts by weight of the composite membrane.

In the copolymer containing the first repeating unit of Formula 1 and the second repeating unit of Formula 2, the molar ratio of the first repeating unit represented by Formula 1 and the second repeating unit represented by Formula 2 is 1:99 to 99. :1. In the copolymer, the molar ratio between the first repeating unit represented by Formula 1 and the second repeating unit represented by Formula 2 may be 1:1 to 4:1. When the content of the first repeating unit represented by Formula 1 is within the above-described range, a composite membrane with excellent ionic conductivity can be manufactured without deteriorating the mechanical strength of the copolymer and the composite membrane containing it.

The copolymer according to one embodiment may be a copolymer represented by the following formula (6).

[Formula 6]

In Formula 6, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group,

R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,

A simply represents a chemical bond or is an unsubstituted or substituted C1-C30 alkylene group, or an unsubstituted or substituted C6-C30 arylene group,

is a group represented by the following formula 5,

[Formula 5]

In Formula 5, R ₂₀ to R ₂₈ are each independently hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, Unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or substituted C4-C30 cyclo It is an alkyl group or an unsubstituted or substituted C3-C30 heterocycloalkyl group, * represents the binding region,

Y ^- is BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , CH ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , (FSO ₂ ) ₂ N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , and (O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- and one or more anions selected from ,

m and n are each 0.01 to 0.99 and their sum is 1.

The copolymer may be one or more compounds selected from the following Chemical Formulas 6a, 6b, 6c, and 6d.

[Formula 6a] [Formula 6b]

[Formula 6c] [Formula 6d]

In Formulas 6a to 6d, Y ^- is PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , CH ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , (FSO ₂ ) ₂ N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , and (O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- . , a is an integer from 1 to 10, R ₂₄ is an alkyl group of C1-C10, m and n are each 0.01 to 0.99 and their sum is 1, and the degree of polymerization is a number from 10 to 5000.

For example, the copolymer may be a copolymer represented by the following formulas 6e, 6f, or 6g.

[Formula 6e] [Formula 6f]

[Formula 6g]

In the formulas 6e, 6f and 6g, a is an integer from 1 to 10, m and n are each from 0.01 to 0.99 and their sum is 1, and the degree of polymerization is a number from 10 to 5000.

The degree of polymerization of the copolymer ranges from 10 to 5,000. And the weight average molecular weight of the copolymer is 3,000 Dalton to 400,000 Dalton, for example, 5,000 to 200,000 Dalton. When the degree of polymerization and weight average molecular weight of the copolymer are within the above-mentioned range, the mechanical strength of the copolymer is excellent and the growth of lithium dendrites can be effectively suppressed, thereby further improving the performance of the lithium battery. The weight average molecular weight was measured on a PMMA (polymethylmethacylate) standard sample using GPC (Gel Permeation Chromatography).

For example, the polydispersity index (PDI) of the copolymer may be 1 to 3, for example 1 to 2.0, for example 1.2 to 2.8. By including a copolymer having the above polydispersity index range, the performance of a lithium battery can be further improved.

The glass transition temperature (T _g ) of the copolymer may be 30 to 90. For example, when the weight average molecular weight of the copolymer is 37,000 Dalton, the glass transition temperature (T _g ) may be 55. The performance of a lithium battery can be further improved by including a copolymer having a glass transition temperature in the above range.

The copolymer can be electrochemically stable down to -0.4 V relative to lithium. In other words, the copolymer can ignore the reduction current due to the side reaction of the random copolymer up to -0.4 V with respect to lithium. For example, the copolymer may have a voltage in the range of -0.4 V to 6.2 V relative to lithium metal, such as in the range of -0.4 V to 5.5 V, such as in the range of -0.4 V to 5.0 V, such as -0.4 V relative to lithium metal. It can provide a wide electrochemically stable potential window of 4.5V to 4.5V.

The composite membrane according to one embodiment can be used as an electrolyte. When the electrolyte contains the above-described copolymer, an electrolyte with improved durability and ionic conductivity can be obtained. Additionally, the charge/discharge characteristics of lithium batteries containing such electrolytes can be improved.

The electrolyte containing the copolymer may additionally include a lithium salt. Lithium salts are for example LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN(SO ₂ C ₂ F ₅ ) ₂ , Li(CF ₃ SO ₂ ) ₂ N, Li(FSO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiClO ₄ , LiAlO ₂ , LiAlCl ₄ , LiN(C _x F _{2x + 1} SO ₂ )(C _y F _{2y + 1} SO ₂ ) (where x and y are 1 to 30), LiF, LiBr, One or two selected from the group consisting of LiCl, LiI, LiB(C ₂ O ₄ ) ₂ (lithium bis(oxalato) borate; LiBOB), LiTFSI (Lithium Bis(Trifluoromethanesulfonyl)Imide), and LiNO ₃ It may be the above, but is not necessarily limited to these, and any lithium salt that can be used as a lithium salt in the relevant technical field is possible.

Additionally, the electrolyte containing the random copolymer may additionally contain other polymers. The added polymer is not particularly limited, and any polymer that can be used as an electrolyte in the art is possible. For example, the electrolyte may additionally include polyethylene oxide, polyvinyl alcohol (PVA), etc.

Additionally, the electrolyte containing the copolymer may be a liquid electrolyte or a solid electrolyte.

For example, the liquid electrolyte containing the copolymer may additionally include one or more selected from organic solvents and ionic liquids and may be in a liquid state at room temperature.

Organic solvents may include aprotic solvents. As an aprotic solvent, for example, a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent can be used. The carbonate-based solvents include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), and ethylene carbonate ( EC), propylene carbonate (PC), butylene carbonate (BC), etc. can be used, and the ester-based solvents include methyl acetate, ethyl acetate, n-propyl acetate, tertbutyl acetate, methyl propionate, and ethyl propio. Nate, gammabutyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, etc. can be used. The ether-based solvent may be dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc., and the ketone-based solvent may include cyclohexanone. there is. In addition, ethyl alcohol, isopropyl alcohol, etc. may be used as the alcohol-based solvent, but are not necessarily limited to these, and any protic solvent that can be used in the art can be used. Examples of the organic solvent include tetraethylene glycol. Dimethyl ether (TEGDME), etc. may be used.

Ionic liquids are ionic substances that are in a molten state at room temperature (25°C) and can be used without limitation as long as they contain cations and anions. Ionic liquids include, but are not limited to, imidazolium, ammonium, pyrrolidinium, or piperidinium as cations, and include, but are not limited to, bis( Includes bis(fluorosulfonyl)imide, fluorosufonylamide, fluoroborate, or fluorophosphate. Specific examples of the cation include alkylammonium such as triethylammonium, imidazolium such as ethylmethylimidazolium and butylmethylimidazolium, and pyrrolidinium such as 1-methyl-1-propylpyrrolidinium. . In addition, specific examples of anions include bis(trifluoromethylsulfonyl)imide (TFSI), bis(pentafluoroethylsulfonyl)imide (BETI), Examples include tetrafluoroborate (BF ₄ ), or hexafluorophosphate (PF ₆ ).

Ionic liquids include, for example, [emim]Cl/AlCl ₃ (emim = ethyl methyl imidazolium), [bmpyr]NTf2 (bppyr = butyl methyl pyridinium), [bpy]Br/AlCl ₃ (bpy = 4, 4'- bipyridine), [choline]Cl/CrCl ₃ 6H ₂ O, [Hpy(CH ₂ ) ₃ pyH][NTf ₂ ] ₂ (NTf2 = bistrifluoromethanesulfonimide), [emim]OTf/[hmim]I(hmim = hexyl methyl imidazolium ), [choline]Cl/HOCH ₂ CH ₂ OH, [Et ₂ MeN(CH ₂ CH ₂ OMe)]BF ₄ (Et = ethyl, Me = methyl, Pr = propyl, Bu = butyl, Ph = phenyl, Oct = octyl, Hex = hexyl), [Bu ₃ PCH ₂ CH ₂ C ₈ F ₁₇ ]OTf(OTf = trifluoromethane sulfonate), [bmim]PF ₆ (bmim = butyl methyl imidazolium), [bmim]BF ₄ , [omim]PF ₆ (omim = octyl methyl imidazolium), [Oct ₃ PC ₁₈ H ₃₇ ]I, [NC(CH ₂ ) ₃ mim]NTf ₂ (mim = methyl imidazolium), [Pr ₄ N][B(CN) ₄ ], [bmim]NTf ₂ , [bmim]Cl, [bmim][Me(OCH ₂ CH ₂ ) ₂ OSO ₃ ], [PhCH ₂ mim]OTf, [Me ₃ NCH(Me)CH(OH)Ph] NTf ₂ , [pmim][(HO) ₂ PO ₂ ] (pmim = propyl methyl imidazolium), [(6-Me)b quin]NTf ₂ (bquin = butyl quinolinium, [bmim][Cu ₂ Cl ₃ ], [C ₁₈ H ₃₇ OCH ₂ mim]BF ₄ (mim = methyl imidazolium), [heim]PF ₆ (heim = hexyl ethyl imidazolium), [mim(CH ₂ CH ₂ O) ₂ CH ₂ CH ₂ mim][NTf ₂ ] ₂ (mim = methyl imidazolium), [obim]PF ₆ (obim = octyl butyl imidazolium), [oquin]NTf ₂ (oquin = octyl quinolinium), [hmim][PF ₃ (C ₂ F ₅ ) ₃ ], [C ₁₄ H ₂₉ mim]Br(mim = methyl imidazolium), [Me ₂ N(C ₁₂ H ₂₅ ) ₂ ]NO ₃ , [emim]BF ₄ , [mm(3-NO ₂ )im][dinitrotriazolate], [MeN(CH ₂ CH ₂ OH) ₃ ][MeOSO ₃ ], [Hex ₃ PC ₁₄ H ₂₉ ]NTf ₂ , [emim][EtOSO ₃ ], [choline][ibuprofenate], [emim]NTf ₂ , [emim][(EtO) ₂ PO ₂ ], [emim]Cl/CrCl ₂ , [Hex ₃ PC ₁₄ H ₂₉ ]N(CN) ₂ , etc., but are not necessarily limited to these, and any liquid that can be used as an ionic liquid in the art is possible. do.

The solid electrolyte containing the copolymer is solid at room temperature and may not contain an organic solvent.

The solid electrolyte is used at temperatures below 50°C, such as below 30°C, such as below 25°C.

It may be solid. According to one embodiment, the solid electrolyte may have a solidification temperature of 0 to 50°C, for example, 5 to 40°C, for example, 10 to 30°C. Because the electrolyte contains a copolymer, it may be solid at room temperature. The solid electrolyte may be a solvent free electrolyte. The solid electrolyte may contain no solvent. For example, the solid electrolyte may be a solid polymer electrolyte that contains only a copolymer and a lithium salt and does not contain a solvent. Since the electrolyte does not contain a solvent, problems such as side reactions and leakage caused by the solvent can be prevented.

Solvent-free solid electrolytes are distinguished from polymer gel electrolytes in which solid polymers contain a small amount of solvent. For example, the polymer gel electrolyte may have improved ionic conductivity by containing a small amount of solvent in the ionic conductive polymer.

When the composite film according to one embodiment is used as a lithium negative electrode protective film, the protective film includes a copolymer, thereby suppressing the formation of dendrites on the surface of the negative electrode during the charging and discharging process in the lithium battery, thereby improving the charging and discharging characteristics of the lithium battery. You can.

The negative electrode includes, but is not limited to, lithium metal, a lithium metal-based alloy, or a material capable of inserting and releasing lithium, and is not necessarily limited to these and can be used as a negative electrode in the art and contains lithium or is capable of inserting and releasing lithium. Any material available is possible. The cathode may be lithium metal, for example. The lithium metal-based alloy may be, for example, an alloy of lithium with aluminum, tin, magnesium, indium, calcium, titanium, vanadium, etc.

The protective film may additionally include lithium salt. By additionally including lithium salt, the ionic conductivity of the protective film can be increased and the interfacial resistance between the cathode and the electrolyte can be reduced. The lithium salt may be the same as the lithium salt contained in the electrolyte containing the above-mentioned copolymer.

The thickness of the composite membrane may be 1 nm to 1000 μm, such as 0.1 μm to 100 μm, such as 0.5 to 70 μm, such as 1 to 50 μm, such as 1 to 20 μm. By including a composite film in the above thickness range, the function of protecting the lithium negative electrode is excellent and the transfer of lithium ions is facilitated, thereby improving the charge and discharge characteristics of the lithium battery.

The composite film can be disposed on one or both sides of the cathode and the composite film can cover the cathode. By covering the entire cathode with the composite film, the formation of dendrites can be effectively suppressed on the entire cathode surface.

The composite membrane may have a single-layer structure or a multi-layer structure. Because the composite membrane has a multilayer structure, the overall physical properties of the composite membrane can be easily adjusted by varying the composition of each layer in the plurality of layers. In a composite membrane having a multilayer structure, at least one layer may include a copolymer.

The lithium ion conductivity of the composite membrane at 25°C is 0.001 mS/cm or more, for example, 0.01 to 0.5 mS/cm.

According to different aspects, a lithium battery has an anode; cathode; and a composite membrane disposed between them.

The composite membrane may be an electrolyte disposed between the anode and the cathode in a lithium battery. For example, the lithium battery may further include a liquid electrolyte or a solid electrolyte. The lithium battery may be a lithium ion battery or a lithium air battery. Additionally, the lithium battery may be a primary battery or a secondary battery.

A lithium battery may be a lithium negative electrode containing a lithium metal or lithium alloy electrode as the negative electrode. A lithium battery using a lithium negative electrode is a lithium metal battery.

the negative electrode is a lithium metal or lithium metal alloy electrode; Alternatively, the negative electrode may be selected from carbon-based materials, silicon, silicon oxide, silicon-based alloys, silicon-carbon-based material composites, tin, tin-based alloys, tin-carbon composites, metals/metalloids alloyable with lithium, alloys thereof, or oxides thereof. It may include one or more selected anode active materials.

The cathode is a lithium metal or lithium metal alloy electrode, and the composite membrane is a cathode protective film or a cathode protective film and electrolyte.

The composite membrane can be used as an electrolyte.

The lithium battery may further include one or more selected from liquid electrolyte, solid electrolyte, gel electrolyte, and polymer ionic liquid.

The positive electrode may contain a positive electrode active material and a copolymer including a first repeating unit represented by Formula 1 and a second repeating unit represented by Formula 2. In this way, when the positive electrode contains a copolymer containing the first repeating unit represented by Formula 1 and the second repeating unit represented by Formula 2, lithium ion mobility is excellent, electrochemically stable, and mechanical properties are improved. The electrochemical properties of lithium batteries can be improved.

The operating voltage of the lithium battery is 4.0V or more.

According to another aspect, a positive electrode for a lithium battery is provided, including a positive electrode active material and a copolymer including a first repeating unit represented by Formula 1 and a second repeating unit represented by Formula 2.

Lithium batteries can be manufactured, for example, by the following method.

First, the anode is prepared. As the anode, an anode according to an embodiment may be used, or a general anode may be used.

For example, a positive electrode active material composition is prepared by mixing a positive electrode active material, a conductive agent, a binder, and a solvent. A positive electrode is manufactured by coating and drying the positive electrode active material composition directly on a metal current collector. The positive electrode active material composition may further include a copolymer including a first repeating unit represented by the above-described formula (1) and a second repeating unit represented by the formula (2). Alternatively, the positive electrode active material composition may be cast on a separate support, and then the film peeled from the support may be laminated on a metal current collector to produce a positive electrode plate.

The positive electrode active material may include one or more selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide, but is not necessarily limited to these and may be used in the technical field. Any available cathode active material can be used.

For example, Li _a A _{1 - b} B _b D ₂ (in the above formula, 0.90≤a≤1.8, and 0≤b≤0.5); Li _a E _{1 -b} B _b O _2-c D _c (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE _{2 - b} B _b O _{4 - c} D _c (in the above formula, 0≤b≤0.5, 0≤c≤0.05); Li _a Ni _{1 -b- c} Co _b B _c D _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li _a Ni _{1 -b- c} Co _b B _c O _{2 - α} F _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _{1 -b- c} Co _b B _c O _{2 - α} F ₂ (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _{1 -bc} Mn _b B _c D _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li _a Ni _{1 -bc} Mn _b B _c O _2-α F _α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - α} F ₂ (in the above formula, 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 (In the above formula, 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 (In the above formula, 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 (In the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a CoG _b O ₂ (In the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a MnG _b O ₂ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO 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); Compounds represented by any of the chemical formulas of LiFePO ₄ can be used:

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination 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 a combination thereof.

Of course, a compound having a coating layer on the surface can be used, or a mixture of the above compound and a compound having a coating layer can be used. This coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide of the coating element, oxycarbonate of the coating element, or hydroxycarbonate of the coating element. The compounds that make up these coating layers may be amorphous or crystalline. Coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. For the coating layer formation process, any coating method may be used as long as these elements can be used in the compound to coat the compound in a manner that does not adversely affect the physical properties of the positive electrode active material (e.g., spray coating, dipping method, etc.). Since this is well-understood by people working in the field, detailed explanation will be omitted.

For example, LiNiO ₂ , LiCoO ₂ , LiMn _x O _2x (x=1 or 2), LiNi _{1 -x Mn x} O ₂ (0<x<1), LiNi _{1 -xy} Co _x Mn _y O ₂ (0 ≤x≤0.5, 0≤y≤0.5), LiFeO ₂ , V ₂ O ₅ , TiS, MoS, etc. may be used.

The conductive agent includes carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, Ketjen black, and carbon fiber; Metal powders, metal fibers, or metal tubes such as carbon nanotubes, copper, nickel, aluminum, and silver; Conductive polymers such as polyphenylene derivatives may be used, but are not limited to these, and any conductive agent that can be used in the relevant technical field can be used.

The binder includes vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, polyimide, polyethylene, polyester, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), Carboxymethyl cellulose-styrene-butadiene rubber (SMC/SBR) copolymer, styrene butadiene rubber-based polymer, or mixtures thereof may be used.

The solvent may be N-methylpyrrolidone, acetone, or water.

It is not limited to these and anything that can be used in the relevant technical field can be used.

The contents of the composite positive electrode active material, conductive agent, binder, and solvent are levels commonly used in lithium batteries. Depending on the use and configuration of the lithium battery, one or more of the conductive agent, binder, and solvent may be omitted.

The negative electrode can be obtained by almost the same method, except that the negative electrode active material is used instead of the positive electrode active material in the positive electrode manufacturing process described above.

As the negative electrode active material, carbon-based materials, silicon, silicon oxide, silicon-based alloys, silicon-carbon-based material composites, tin, tin-based alloys, tin-carbon composites, metal oxides, or combinations thereof are used.

The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be amorphous, plate-shaped, flake-shaped, spherical or fibrous, such as natural graphite or artificial graphite, and the amorphous carbon may be soft carbon (low-temperature sintered carbon) or hard carbon. carbon), mesophase pitch carbide, calcined coke, graphene, carbon black, fullerene soot, carbon nanotubes, and carbon fiber, but are not necessarily limited to these and are used in the technical field. Anything that can be used is possible.

The negative electrode active material may be selected from the group consisting of Si, SiOx (0 <x <2, for example, 0.5 to 1.5), Sn, SnO ₂ , or silicon-containing metal alloys and mixtures thereof. As a metal that can form the silicon alloy, one or more of Al, Sn, Ag, Fe, Bi, Mg, Zn, in, Ge, Pb, and Ti can be selected and used.

The negative electrode active material may include metals/metalloids capable of alloying with lithium, alloys thereof, or oxides thereof. For example, the metals/metalloids that can be alloyed with lithium, their alloys, or oxides thereof include Si, Sn, Al, Ge, Pb, Bi, Sb, and Si-Y alloy (where Y is an alkali metal, alkaline earth metal, 13 Group to Group 16 elements, transition metals, rare earth elements, or a combination thereof, but not Si), Sn-Y alloy (Y is an alkali metal, alkaline earth metal, Group 13 to Group 16 elements, transition metal, rare earth element, or It may be a combination of these elements, but not Sn), MnOx (0 < x ≤ 2), etc. The element Y includes 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, Tl, Ge, P, As, Sb, Bi, S, It may be Se, Te, Po, or a combination thereof. For example, the oxide of a metal/metalloid alloyable with lithium may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO ₂ , SiO _x (0<x<2), etc.

For example, the negative electrode active material may include one or more elements selected from the group consisting of group 13 elements, group 14 elements, and group 15 elements of the periodic table of elements. For example, the negative electrode active material may include one or more elements selected from the group consisting of Si, Ge, and Sn.

The contents of the negative electrode active material, conductive agent, binder, and solvent are levels commonly used in lithium batteries.

Next, a separator may be further inserted between the anode and the cathode.

The separator is sandwiched between the anode and the cathode, and a thin insulating film with high ion permeability and mechanical strength is used.

The pore diameter of the separator is generally 0.01 to 10 ㎛, and the thickness is generally 5 to 20 ㎛. Examples of such separators include olefin polymers such as polypropylene and polyethylene; Sheets or non-woven fabrics made of glass fiber or polyethylene are used. When a solid polymer electrolyte is used as the electrolyte, the solid polymer electrolyte may also serve as a separator.

Specific examples of the olefinic polymer among the above separators include polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof, such as a two-layer polyethylene/polypropylene separator or a three-layer polyethylene/polypropylene/polyethylene separator. Mixed multilayer films such as separators, polypropylene/polyethylene/polypropylene three-layer separators, etc. can be used.

Next, the electrolyte is prepared. Electrolytes may be in a liquid or gel state. The electrolyte may include the random copolymer described above.

For example, the electrolyte may be an organic liquid electrolyte. Organic liquid electrolytes can be prepared by dissolving lithium salt in an organic solvent. The organic solvent may be the aprotic solvent described above. Lithium salt included in the above-mentioned electrolyte may also be used.

Alternatively, the electrolyte may be solid. For example, it may be boron oxide, lithium oxynitride, etc., but it is not limited to these, and any solid electrolyte that can be used in the art can be used. A solid electrolyte may be formed on the cathode by a method such as sputtering.

As shown in FIG. 9, the lithium battery 91 includes an anode 93, a cathode 92, and a composite membrane 94. The above-described positive electrode 93, negative electrode 92, and composite film 94 are wound or folded and accommodated in the battery case 95. Next, an organic electrolyte solution is injected into the battery case 95 and sealed with a cap assembly 96 to complete the lithium battery 91. The battery case may be cylindrical, prismatic, thin film, etc. For example, the lithium battery may be a thin film type battery.

For example, the lithium battery may be a lithium ion polymer battery. In a lithium ion polymer battery, a separator is placed between the positive and negative electrodes to form a battery structure. The battery structure is then stacked or wound in a bi-cell structure and then impregnated with an organic electrolyte solution. The resulting product is placed in a pouch and sealed to complete the process. do.

Additionally, a plurality of battery structures are stacked to form a battery pack, and this battery pack can be used in all devices that require high capacity and high output. For example, it can be used in laptops, smartphones, electric vehicles, etc.

In particular, lithium batteries have excellent thermal stability and provide good battery characteristics, making them suitable for electric vehicles (EV). For example, it is suitable for hybrid vehicles such as plug-in hybrid electric vehicle (PHEV).

Alternatively, the lithium battery may be a lithium air battery.

Lithium-air batteries can be prepared, for example, as follows.

First, an air electrode is prepared as an anode. For example, the air electrode can be manufactured as follows. As the electrode member, a conductive agent and a binder are mixed, then an appropriate solvent is added or mixed without adding a solvent to prepare a cathode slurry, which is then applied and dried on the surface of the current collector, or optionally used on the current collector to improve electrode density. It can be manufactured by compression molding. The current collector may be a gas diffusion layer. Alternatively, the cathode slurry can be prepared by applying and drying it on the surface of the separator or solid electrolyte membrane, or optionally by compression molding it on the separator or solid electrolyte membrane to improve electrode density.

The conductive material included in the cathode slurry may be porous. Therefore, any material that is porous and conductive can be used without limitation. For example, a porous carbon-based material can be used. As such carbon-based materials, carbon black, graphite, graphene, activated carbon, carbon fiber, etc. can be used.

A catalyst for oxidation/reduction of oxygen may be added to the cathode slurry. Such catalysts include noble metal catalysts such as platinum, gold, silver, palladium, ruthenium, rhodium, and osmium, manganese oxide, iron oxide, cobalt oxide, and nickel. Oxide-based catalysts such as oxides or organometallic catalysts such as cobalt phthalocyanine can be used, but are not necessarily limited to these, and any catalyst that can be used as an oxygen oxidation/reduction catalyst in the art is possible.

Additionally, the catalyst may be supported on a carrier. The carrier may be oxide, zeolite, clay-based mineral, carbon, etc. The oxide may include one or more oxides such as alumina, silica, zirconium oxide, and titanium dioxide. It may be an oxide containing one or more metals selected from Ce, Pr, Sm, Eu, Tb, Tm, Yb, Sb, Bi, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo and W. . The carbon may be carbon blacks such as Ketjen black, acetylene black, channel black, and lamp black, graphites such as natural graphite, artificial graphite, and expanded graphite, activated carbon, and carbon fibers, but is not necessarily limited to these and is not limited to the technology. Anything that can be used as a carrier in the field is possible.

The air cathode slurry may include a binder. The binder may include a thermoplastic resin or thermosetting resin. For example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene rubber, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-hexafluoride. Fluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoro propylene copolymer, propylene-tetrafluoro Ethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene copolymer, ethylene- Acrylic acid copolymers, etc. can be used alone or in combination, but are not necessarily limited to these, and any binder that can be used as a binder in the relevant technical field can be used.

The current collector may use a porous material such as a network or mesh shape to speed up the diffusion of oxygen, and a porous metal plate such as stainless steel, nickel, or aluminum may be used, but is not necessarily limited to these, and is used as a current collector in the art. Anything that can be used is possible. The current collector may be coated with an oxidation-resistant metal or alloy film.

The cathode slurry may optionally include a conventional oxygen oxidation/reduction catalyst and a conductive material. Additionally, the cathode slurry may optionally include lithium oxide.

The above-described composite membrane for a lithium battery is disposed between the air electrode and the cathode. It may further include a separator used in lithium batteries.

Additionally, in a lithium air battery, an oxygen blocking film that is impermeable to oxygen may be additionally disposed between the air electrode and the cathode. Lithium-air batteries with an impervious oxygen barrier may not contain a typical separator. The oxygen blocking film is a lithium ion conductive solid electrolyte film that can serve as a protective film to prevent impurities such as oxygen contained in the air electrode from reacting directly with the lithium metal cathode. Examples of materials for forming a lithium ion conductive solid electrolyte membrane that are impermeable to oxygen include inorganic materials containing lithium ion conductive glass, lithium ion conductive crystals (ceramic or glass-ceramic), or mixtures thereof, but these are not necessarily the same. Unless limited to this, any solid electrolyte membrane that has lithium ion conductivity, is impermeable to oxygen, and can protect the cathode can be used as long as it can be used in the technical field. Meanwhile, when considering chemical stability, the lithium ion conductive solid electrolyte membrane may be an oxide.

For example, the oxygen barrier film containing lithium ion conductive crystals is Li _1+x+y Al _x (Ti,Ge) _2-x Si _y P _3-y O _1, 0≤x≤2, 0≤y≤3 ) and, for example, a solid electrolyte membrane containing LATP (Li _1.4 Ti _1.6 Al _0.4 P ₃ O ₁₂ ).

Next, electrolyte is injected between the air electrode and the cathode. The same electrolyte used in lithium batteries can be used.

The shape of the lithium air battery is not particularly limited, and examples include coin shape, button shape, sheet shape, stacked shape, cylindrical shape, flat shape, and horn shape. It can also be applied to large batteries used in electric vehicles, etc.

The term “air” as used herein is not limited to atmospheric air, and may include a combination of gases containing oxygen, or pure oxygen gas. This broad definition of the term “air” can be applied to all applications, such as air cells, air cathodes, etc.

The copolymer according to one embodiment can be produced as a random copolymer or a block copolymer according to a synthesis method. For example, block copolymers can be produced using anionic polymerization, CTA (chain transfer agent), etc.

Hereinafter, the synthesis process of the copolymer will be examined in more detail as an example.

First, a copolymer represented by Formula 9 can be obtained by performing a polymerization reaction of the first monomer represented by Formula 7 below and the second monomer represented by Formula 8 below.

[Formula 7] [Formula 8]

In Formula 7, R ₁ to R ₃ , Ar 1 , and A are as defined in Formula 1, and X is a halogen atom. Halogen atoms are for example Cl, Br, or I.

In Formula 8, R ₄ to R ₇ and a are as defined in Formula 2.

[Formula 9]

_{In Formula 9 ,} Their sum as the mole fraction of the unit is 1, and is a number from 0.1 to 0.99.

The copolymer represented by Formula 9 is reacted with the compound represented by Formula 10 so that Changes to X ^- . Subsequently, a compound containing Y ^- can be added to the resultant and reacted to obtain the desired copolymer.

[Formula 10]

In formula 10, is a 3- to 31-membered ring containing 2 to 30 carbon atoms, It's like a bar.

The compound represented by Formula 10 is a 3- to 31-membered ring compound containing 2 to 30 carbon atoms, and X is as defined in Formula 1.

Examples of compounds represented by Formula 10 include N-methylpyrrolidine and N-methylimidazole. For compounds containing Y ^-, for example, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, etc. are used.

In the copolymer production method, the polymerization method may be solution polymerization, but is not necessarily limited to these, and any method that can be used as a polymer production method in the art is possible. Polymerization temperature and polymerization time are also not particularly limited and may be changed appropriately.

The copolymer according to one embodiment has a first repeating unit as described above. Y ^- first synthesizes the copolymer represented by Formula 9, and then sequentially reacts it with the compound represented by Formula 10 and the compound containing Y ^- to form X present at the end of the copolymer. Y ^- can be changed to produce the desired copolymer. Alternatively, the copolymer according to one embodiment can also be produced by copolymerizing a first monomer represented by Formula 7a below and a second monomer represented by Formula 8.

[Formula 7a]

In Formula 7a, R ₁ to R ₃ , Ar ₁ , A, Y ^- , is as defined in Formula 1.

According to another aspect, a copolymer comprising a first repeating unit represented by the above-described formula 1 and a second repeating unit represented by the formula 2 is provided. This copolymer may be a random copolymer as described above.

The definitions of substituents used in the chemical formulas of this specification are as follows.

An alkyl group refers to a group of fully saturated branched or unbranched (or straight-chain or linear) hydrocarbons. Non-limiting examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2 , 2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, etc. Among the alkyl, at least one hydrogen atom is a halogen atom, a C1-C20 alkyl group substituted with a halogen atom (e.g. CF ₃ , CH ₃ CF ₂ , CH ₂ F, CCl _3, etc.), a C1-C20 alkoxy group, C2-C20 alkoxyalkyl group, hydroxy group, nitro group, cyano group, amino group, alkylamino group, amidino group, hydrazine, hydrazone, carboxyl group or salt thereof, sulfonyl group, sulfamoyl group, sulfonic acid group or salt thereof, phosphoric acid or salt thereof , or C1-C20 alkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C1-C20 heteroalkyl group, C6-C20 aryl group, C7-C20 arylalkyl group, C6-C20 heteroaryl group. , a C7-C20 heteroarylalkyl group, a C6-C20 heteroaryloxy group, a C6-C20 heteroaryloxyalkyl group, or a C6-C20 heteroarylalkyl group.

An alkenyl group refers to an aliphatic hydrocarbon containing one or more double bonds, and an alkynyl group refers to an aliphatic hydrocarbon containing one or more triple bonds.

Cycloalkyl group refers to an aliphatic hydrocarbon containing one or more rings. At this time, the alkyl group is as described above. Heterocycloalkyl group refers to a cycloalkyl group containing one or more heteroatoms selected from N, O, P, or S. At this time, the cycloalkyl group is the same as described above.

Halogen atoms include fluorine, bromine, chlorine, iodine, etc.

The alkoxy group represents an alkyl group -O-, and in this case, the alkyl group is as described above. Non-limiting examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, 2-propoxy group, butoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, cyclopropoxy group, and cyclohexyloxy group. etc. One or more hydrogen atoms in the alkoxy group may be substituted with the same substituent as in the case of the alkyl group described above.

The cycloalkyloxy group represents a cycloalkyl group -O-, and in this case, the cycloalkyl group is as described above. The heterocycloalkyloxy group represents a heterocycloalkyl group -O-, and in this case, the heterocycloalkyl group is as described above.

Aryl group, used alone or in combination, refers to an aromatic hydrocarbon containing one or more rings. Aryl groups also include groups in which an aromatic ring is fused to one or more cycloalkyl rings. Non-limiting examples of the aryl include phenyl group, naphthyl group, tetrahydronaphthyl group, etc. Additionally, one or more hydrogen atoms in the aryl group may be replaced with the same substituent as in the case of the alkyl group described above.

In the arylalkyl group, the alkyl group and aryl group are as described above.

The aryloxy group represents an aryl group -O-, and in this case, the aryl group is as described above.

The arylthio group represents an aryl group -S-, and in this case, the aryl group is as described above.

Heteroaryl group refers to a monocyclic or bicyclic organic compound containing one or more heteroatoms selected from N, O, P, or S, and the remaining ring atoms are carbon. For example, the heteroaryl group may contain 1-5 heteroatoms and 5-10 ring members. The S or N may be oxidized and have various oxidation states.

Monocyclic heteroaryl groups include, for example, thienyl group, furyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, thiazolyl group, isothiazolyl group, 1,2,3-oxadiazolyl group, 1,2 ,4-oxadiazolyl group, 1,2,5-oxadiazolyl group, 1,3,4-oxadiazolyl group, 1,2,3-thiadiazolyl group, 1,2,4-thiadiazolyl group, 1,2,5-thiadiazolyl group, 1,3,4-thiadiazolyl group, isothiazol-3-yl group, isothiazol-4-yl group, isothiazol-5-yl group, oxazole -2-yl group, oxazol-4-yl group, oxazol-5-yl group, isoxazol-3-yl group, isoxazol-4-yl group, isoxazol-5-yl group, 1,2,4-tria Zol-3-yl group, 1,2,4-triazol-5-yl group, 1,2,3-triazol-4-yl group, 1,2,3-triazol-5-yl group, tetrazolyl group, p Lead-2-yl group, pyrid-3-yl group, 2-pyrazine-2-yl group, pyrazine-4-yl group, pyrazine-5-yl group, 2-pyrimidin-2-yl group, 4-pyrimidin-2-yl group, or 5-pyrimidin-2-yl group, etc.

Heteroaryl includes heteroaromatic rings fused to one or more aryl, cycloaliphatic, or heterocycles.

Examples of bicyclic heteroaryls include indolyl, isoindolyl, indazolyl, indolizinyl, purinyl, quinolizinyl, and quinolyl. There are quinolinyl, isoquinolinyl, etc. One or more hydrogen atoms in such heteroaryl can be substituted with the same substituent as in the case of the alkyl group described above.

The aryl group in the heteroarylalkyl group is as described above. The heteroaryloxy group represents a heteroaryl group -O-, and in this case, the heteroaryl group is as described above. And the heteroarylthio group represents a heteroaryl group -S-, and in this case, the heteroaryl group is as described above.

Alkylene, arylene, heteroarylene, cycloalkylene, and heterocycloalkylene refer to a substituent in which one hydrogen is removed from alkyl, aryl, heteroaryl, cycloalkyl, and heterocycloalkyl.

This is explained in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and do not limit the scope of the invention.

Manufacturing example One: of random copolymers synthesis

10g of 1-chloromethyl-4-vinylbenzene (manufactured by Oakwood Chemical) and polyoxyethylene methacrylate (A) were added inside the reactor, and 0.075% of AIBN (Azobisisobutyronitrile), a polymerization initiator, was added to the reactor. g was added, and the polymerization reaction proceeded while stirring at 60°C for 15 hours. The molar ratio of 1-chloromethyl-4-vinylbenzene and polyoxyethylene methacrylate was 4:1. After completion of the polymerization reaction, the solvent was removed by evaporation under reduced pressure and precipitated with n-hexane to obtain the polymerization product, random copolymer (B).

[Scheme 1]

In Scheme 1, m and n are each mole fraction, and their sum is 1, m is 0.8, n is 0.2, a is 10, and the degree of polymerization of the random copolymer is controlled so that the weight average molecular weight is about 300,000 Dalton. do.

To the random copolymer (B), 6.13 g of n-methylpyrrolidine (97%, manufactured by Sigma-Aldrich) dissolved in 100 ml of dichloroethane was added and incubated at about 70°C for 9 hours. The reaction was performed to prepare random copolymer (C).

(C)

In the above formula, m is 0.8, n is 0.2, and a is 10.

A random copolymer composition was prepared by adding lithium bis(trifluoromethylsulfonyl)imide (LiTFSI, manufactured by PANAX) and acetone to the random copolymer (C). Random copolymer (C) and LiTFSI were mixed at a molar ratio of 1:1.2, and the acetone content was controlled so that the content of random copolymer (C) was about 10% by weight based on the total weight of the random copolymer composition. The reaction mixture was stirred at room temperature (25°C) for 6 hours to synthesize a random copolymer of Formula 6e in which the Cl ^- anion of random copolymer (C) was replaced with a TFSI ^- anion.

[Formula 6e]

In Formula 6e, m and n are each mole fraction, and their sum is 1, m is 0.8, n is 0.2, a is 10, and the degree of polymerization of the random copolymer of Formula 6e is such that the weight average molecular weight is 300,000 Dalton. It is controlled.

Manufacturing example 2: Preparation of random copolymers

When preparing the random copolymer (B), the same method as Preparation Example 1 was carried out, except that the molar ratio of 1-chloromethyl-4-vinylbenzene and polyoxyethylene methacrylate was changed to 1:1, and the formula 6e was obtained. A random copolymer represented by was prepared. In Formula 6e, both m and n were 0.5.

Manufacturing example 3: Preparation of random copolymers

When preparing the random copolymer (B), the same method as Preparation Example 1 was carried out, except that the molar ratio of 1-chloromethyl-4-vinylbenzene and polyoxyethylene methacrylate was changed to 2:1, and the formula 6e was obtained. A random copolymer represented by was prepared. In Formula 6e, m and n were 0.67 and 0.23, respectively.

Manufacturing example 4: of random copolymers synthesis

Instead of lithium bis(trifluoromethylsulfonyl)imide added to the random copolymer (C), lithium bis(fluorosulfonyl)imide (LiFSI, manufactured by PANAX) was used. Except, a random copolymer represented by the following formula 6f was prepared by following the same method as Preparation Example 1.

[Formula 6f]

In Formula 6f, m and n are each mole fraction, and their sum is 1, m is 0.8, n is 0.2, a is 10, and the degree of polymerization is such that the weight average molecular weight of the random copolymer of Formula 6f is 300,000 Dalton. It is controlled.

Manufacturing example 5: Preparation of random copolymers

A random copolymer represented by Formula 6g was prepared in the same manner as Preparation Example 1, using the compound of Formula 11 below instead of chloromethyl-4-vinylbenzene.

[Formula 11] [Formula 6g]

In the formula 6g, m is 0.8, n is 0.2, a is 10, and the degree of polymerization of the random copolymer of the formula 6g is controlled so that the weight average molecular weight is 300,000 Dalton.

Comparative manufacturing example One: of random copolymers manufacturing

10 g of 1-chloromethyl-4-vinylbenzene (manufactured by Oakwood Chemical) was added into the reactor, and 6.13 g of n-methylpyrroli dissolved in 100 ml of dichloroethane was added to it. After adding dine (n-methylpyrrolidine, 97%, manufactured by Sigma-Aldrich), the reaction was carried out with stirring at 70°C for 9 hours to form N-methyl-pyrrolidinium on the methyl group of 1-chloromethyl4-vinylbenzene. An intermediate product containing a nitrogen atom was obtained.

A composition was prepared by adding the intermediate product, lithium bis(trifluoromethylsulfonyl)imide (LiTFSI, manufactured by PANAX), and acetone. The intermediate product and LiTFSI were mixed at a molar ratio of 1:1.2, and the content of acetone was controlled so that the content of the intermediate product was about 10% by weight based on the total weight of the composition. The reaction mixture was stirred at room temperature (25°C) for 6 hours to synthesize vinylbenzyl-4-methyl ^- pyrrolidinium ⁺ TFSI ^- (mVBMPYR ⁺ TFSI ^- ) monomer in which the Cl ^- anion was replaced with the TFSI - anion.

Next, 20 g of styrene and 10.74 g of vinylbenzyl-4-methyl-pyrrolidinium ⁺ TFSI ^- (mVBMPYR ⁺ TFSI ^- ) monomer synthesized above (8:2 molar ratio) were added into the reactor, and AIBN as an initiator was added. 0.75 g of (Azobisisobutyronitrile) was added, and the polymerization reaction was performed while stirring at 60°C for 15 hours. After completion of the polymerization reaction, the solvent was removed using a rotary evaporator and precipitated with methanol to recover the polymerization product, random copolymer (D).

(D)

In the above formula, m is 0.8, n is 0.2, and the polymerization degree of the random copolymer was controlled so that the weight average molecular weight of the obtained random copolymer (D) was 37,000 Dalton. And the polydispersity index (PDI) of random copolymer (D) was 1.55.

Example 1: Lithium battery ( Li / Li symmetric cell )Manufacture of

0.4 g of the random polymer of Chemical Formula 6e prepared in Preparation Example 1 was dissolved in 4 ml of a mixed solvent of dimethylformamide (DMF) and tetrahydrofuran (THF) (5:5 volume ratio) to obtain a polymer solution, and the lithium salt LiTFSI was dissolved in 0.2 ml. g was added and dissolved, the solution was coated on lithium foil with a thickness of 20㎛ using a doctor blade, dried in a drying room at room temperature (25℃) for 2 days, and then vacuum dried (60℃, overnight) to remove the solvent. A protective film containing a random copolymer with a thickness of 5 μm was formed on the lithium anode, and a lithium anode was stacked on the other side of the protective film to prepare a Li/Li symmetric cell. Since the protective film contains a random copolymer, which is a polymeric ionic liquid, and a lithium salt, the protective film can function as an electrolyte.

Example 2-3: Lithium battery ( Li / Li symmetric cell )Manufacture of

A Li/Li symmetric cell was produced in the same manner as in Example 1, except that the random copolymer of Formula 6e prepared in Preparation Examples 2 and 3 was used instead of the random copolymer of Formula 6e prepared in Preparation Example 1. Manufactured.

Example 4: Lithium battery ( full cell )Manufacture of

By carrying out Example 1, a protective film containing a random copolymer with a thickness of 5㎛ was formed on the lithium negative electrode. A full cell was manufactured by stacking an anode on the other side of the protective film.

The anode is LiN _{0 . 6} Co _{0 . 2Mn 0.2} (3.5mAh/cm ² , LiNCM, Samsung SDI), a conductive agent (Super-P; Timcal Ltd.), a copolymer of Formula 6e obtained according to Preparation Example 1, and N _- methylpyrrolidone were mixed. Thus, a positive electrode composition was obtained. In the positive electrode composition, the mixing weight ratio of LiNCM, the conductive agent, and the copolymer of Chemical Formula 6e obtained according to Preparation Example 1 was 70:5:25. The positive electrode composition was coated on aluminum foil (thickness: about 15㎛) and dried at 25°C, and the dried result was dried in a vacuum at about 110°C to prepare a full cell.

Example 5-6: Lithium battery ( full cell )Manufacture of

This was carried out in the same manner as Example 4, except that the copolymers of Preparation Example 4 and Preparation Example 5 were used instead of the copolymers of Preparation Example 1.

Comparative example 1: Lithium battery ( Li / Li symmetric cell )Manufacture of

A Li/Li symmetric cell was manufactured in the same manner as in Example 1, except that the POEM film was formed using polyoxyethylene methacrylate (POEM) instead of the random polymer prepared in Preparation Example 1. It is very difficult to form a POEM membrane in a free-standing state, so a short-circuit prevention membrane in the form of an O-ring with a thickness of about 15㎛ was used when manufacturing the cell. A Celgard separator with a thickness of 12 μm was used as a short-circuit prevention membrane. In this way, it was found that the POEM membrane had insufficient mechanical properties to the extent that it could not be used as a single membrane.

Comparative example 2: Lithium battery ( Li / Li symmetric cell )Manufacture of

A Li/Li symmetric cell was manufactured in the same manner as in Example 1, except that the random copolymer (D) prepared according to Comparative Preparation Example 1 was used instead of the random polymer prepared in Preparation Example 1.

Comparative example 3: Manufacturing of lithium batteries (Li/Li symmetric cells)

A Li/Li symmetric cell was manufactured in the same manner as in Example 1, except that polyethylene oxide (weight average molecular weight: 600,000 Daltons) was used instead of the random polymer prepared in Preparation Example 1.

Comparative example 4: Lithium battery ( full cell )Manufacture of

A full cell was manufactured in the same manner as in Example 4, except that the cathode protective film obtained according to the following process was used as the cathode protective film.

The cathode protective film was manufactured in the same manner as in Example 1, except that the random copolymer (D) prepared according to Comparative Preparation Example 1 was used instead of the random copolymer prepared according to Preparation Example 1.

Evaluation example 1: FT-IR analysis

FT-IR was measured for the random copolymer of Chemical Formula 6e, random copolymer (B), and (C) prepared in Preparation Example 1, and the results are shown in Figure 2. In Figure 2, POEM-PVBCl (polyoxyethylene methacrylate-poly(vinylbenzyl chloride) copolymer), POEM-PVBMPryCl (polyoxyethylene methacrylate-poly(vinylbenzyl-methyl-pyrrolidinium chloride) copolymer), and POEM-PVBMPryTFSI (polyoxyethylene methacrylate-poly(vinylbenzyl-methyl- pyrrolidinium (trifluoromethanesulfonyl)imide) copolymer) refers to random copolymer (B), random copolymer (C), and random copolymer of formula 6e, respectively.

Referring to this, peaks corresponding to the C=C bond and C-H (sp2 orbital) bond derived from the vinyl group of polystyrene were not observed. Additionally, no peak corresponding to the C-Cl bond of 1-chloromethyl-4-vinylbenzene was observed. Therefore, it was confirmed that polymerization proceeded completely and a random copolymer was synthesized.

Evaluation example 2: Nuclear magnetic resonance spectrum (NMR)

NMR analysis was performed on the random copolymer of Formula 6e obtained according to Preparation Example 1, and the results are shown in Figure 3a, and the 2D DOSY (diffusion ordered spectroscopy) NMR spectrum for the random copolymer of Formula 6e is shown in Figure 3b. indicated.

Referring to Figure 3a, the structure of the monomers constituting the random copolymer could be confirmed, and it was found that the random copolymer had a heterogeneous copolymer molecular structure. Additionally, as shown in Figure 3b, it was found to be in the form of a copolymer. Through this NMR analysis, the mixing ratio of the first and second repeating units forming the random copolymer can be confirmed.

Evaluation example 3: Electrochemical stability evaluation

In the Li/Li symmetric cell of Example 1, one of the lithium cathodes was changed to a bare aluminum thin film (thickness 10 μm) to manufacture a Li/Al symmetric cell. In a Li/Al symmetric cell, a lithium cathode was used as a reference electrode, and an aluminum thin film protected by a protective film containing a random copolymer (hereinafter referred to as protective aluminum electrode) was used as a working electrode.

In the Li/Al cell, the cyclic voltammetry was used to scan between -1.5 and 6.0 V relative to lithium metal at a rate of 5 mV/sec to observe whether reduction current was generated due to a side reaction of the protective film. A potentiometer (electrochemical interface (1287 ECI), manufactured by Solartron analytical) was used in the experiment.

The cyclic voltammetry measurement results are shown in Figures 4A and 4B.

Like the bare metal electrode, the protective aluminum electrode only shows a reduction current, in which lithium ions are deposited at a voltage of 0 V or less compared to the lithium metal, and an oxidation current, in which the reduced lithium is dissolved at a voltage of 0 V or more compared to the lithium metal, and is not affected by side reactions of the protective film. No reduction current was shown.

Therefore, the protective film was shown to be electrochemically stable up to -0.5 V for lithium metal. And it was found that the protective film was electrochemically stable against lithium metal even at high voltage. From these results, the electrochemical stability of the electrolyte was confirmed in the operating voltage range of the lithium battery.

Evaluation example 4: Impedance measurement

For the lithium batteries of Comparative Examples 2 and 3 and the lithium battery of Example 1, changes in impedance according to the frequency of alternating voltage were measured using an impedance analyzer (Solartron 1260A Impedance/Gain-Phase Analyzer) at 25°C. The amplitude was 10 mV and the frequency range was 0.1 Hz to 1 MHz.

A Nyquist plot of the impedance measurement results for each lithium battery is shown in Figure 5a. And the interfacial resistance for each lithium battery is shown in Figure 5b.

Referring to FIG. 5A, the difference between the left x-side slice and the right x-side slice of the semicircle represents the interfacial resistance at the electrode. The area specific resistance (ASR) of the lithium battery of Example 1 was reduced by 18% compared to the lithium battery of Comparative Example 3.

As shown in Figure 5b, the interfacial resistance (charge transfer resistance) of the lithium battery of Example 1 was reduced by about 80% compared to the lithium battery of Comparative Example 3.

Evaluation example 5: Lithium ion availability measurement

The lithium ion mobility (lithium transference number), lithium ion conductivity, and lithium transferability of the lithium batteries manufactured according to Example 1 and Comparative Examples 1 and 3 were measured and shown in Figures 6A to 6C, respectively. It was. The lithium transfer probability is defined by equation 1 below.

[Equation 1]

Lithium ion availability = Lithium ion conductivity

Referring to FIG. 6A, the lithium battery of Example 1 has excellent lithium ion conductivity compared to the lithium batteries of Comparative Examples 1 and 3, and as shown in FIG. 6B, the lithium ion mobility of the lithium battery of Example 1 is superior to that of Comparative Examples. It was found that there was an improvement of about 100% compared to Case 1, and a significant improvement compared to Comparative Example 3. And as shown in FIG. 6C, the lithium battery of Example 1 improved the lithium ion availability by about 120% compared to the lithium batteries of Comparative Examples 1 and 3.

Evaluation example 6: charge/discharge characteristic

The lithium battery (Li/Li symmetric cell) manufactured according to Example 1 and Comparative Example 2 was 0.2 mA/cm ² The electrochemical stability of each battery was measured by evaluating Li ion welding and peeling behavior through charging and discharging for 1 hour at a charging and discharging rate of . The electrochemical stability measurement results of the lithium batteries manufactured according to Example 1 and Comparative Example 2 are shown in FIGS. 7A and 7B, respectively.

As shown in Figure 7b, when applying PS-PIL (Comparative Example 2), which is a copolymer with polystyrene (PS), which has better mechanical strength than POEM, an over-potential of about 1V is shown and a short circuit occurs after 120 cycles. As shown in Figure 7a, the lithium battery of Example 1 maintained a relatively low over-potential and showed stable welding/delamination behavior until more than 270 cycles were performed, resulting in an improvement in cycle characteristics of about 125%.

Evaluation example 7: charge/discharge characteristic

The lithium battery prepared in Example 4 and Comparative Example 4 was charged at a constant current of 0.7C from 2.7 V to 4.2V relative to lithium metal at 25°C, and then charged at a constant voltage until the current decreased to 0.025C at 4.2V. Afterwards, it was discharged at a constant current of 0.5C. Subsequently, the above charge/discharge cycle was repeated for a total of 80 charge/discharge cycles. Some of the experimental results are shown in Figures 8A and 8B. The capacity maintenance rate is calculated from Equation 2 below.

<Equation 2>

Capacity maintenance rate (%) = [80th cycle discharge capacity / 1st cycle discharge capacity] × 100

Referring to FIGS. 8A and 8B, it was confirmed that the cycle characteristics of the battery of Example 4 were improved by about 115% compared to Comparative Example 4. In addition, POEM-PIL, which is a copolymer of POEM, a lithium ion conductive polymer, and PIL, which improves lithium ion mobility and improves mechanical properties, can be applied as a polymer electrolyte for lithium batteries using lithium metal to improve electrochemical performance. I was able to confirm that it was there.

In addition, the cycle characteristics of the lithium batteries manufactured according to Examples 5 and 6 were evaluated in the same manner as the cycle characteristics evaluation method of the lithium battery of Example 4 described above.

As a result of the evaluation, it was found that the lithium batteries of Examples 5 and 6 showed equivalent cycle characteristics compared to the lithium batteries of Example 4.

Evaluation example 8: of composite membrane free standing check whether

It was confirmed whether the composite membranes prepared according to Examples 1 to 4 and Comparative Examples 1 to 4 were freestanding at 25°C.

While the composite membranes manufactured according to Examples 1 to 4 had a membrane form capable of freestanding at 25°C, the composite membrane of Comparative Example 1 was not capable of freestanding and had poor film forming properties. And although the composite membranes of Comparative Examples 2 and 4 were capable of free standing, their lithium ion conductivity was poor at about 0.005 mS/cm, making practical application difficult.

The composite membrane of Comparative Example 3 had good lithium ion conductivity, but, like the composite membrane of Comparative Example 1, freestanding was not easy.

91: lithium battery 92: negative electrode
93: anode 94: separator
95: Battery case 96: Cap assembly

Claims (25)

A composite membrane for a lithium battery made of a random copolymer containing a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2).
[Formula 1]

In Formula 1, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group,
R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,
A simply represents a chemical bond, or an unsubstituted or substituted C1-C30 alkylene group, an unsubstituted or substituted C6-C30 arylene group, an unsubstituted or substituted C3-C30 heteroarylene group, or an unsubstituted or substituted It is a C4-C30 cycloalkylene group, or an unsubstituted or substituted C3-C30 heterocycloalkylene group,
is a 3- to 31-membered ring containing 2 to 30 carbon atoms,
X is S, N, N(R) or P(R ^' ),
R and R ^' are independently of each other hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 heteroalkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C7-C30 arylalkyl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C4-C30 heteroarylalkyl group, unsubstituted or substituted C3-C30 cycloalkyl group, unsubstituted or substituted C2-C30 alkenyl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or A substituted C3-C30 heterocycloalkyl group or an unsubstituted or substituted C3-C30 alkynyl group,
Y ^- is an anion,
[Formula 2]

In Formula 2, R ₄ , R ₅ , and R ₆ are independently hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3 -C30 is a heteroaryl group,
R ₇ is hydrogen, an unsubstituted or substituted C1-C20 alkyl group,
Or an unsubstituted or substituted C6-C20 aryl group,
a is an integer from 1 to 10,
In Formulas 1 and 2, m and n are the mole fractions of the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2, respectively, and their sum is 1, which are greater than 0 and less than 1, respectively. According to paragraph 1,
In Formula 1, Ar ₁ is a lithium battery selected from the group consisting of a phenylene group, biphenylene group, naphthalenylene group, phenanthrenylene group, triphenylenylene group, anthracenylene group, fluorenylene group, and carbazolenylene group. Composite membrane. According to paragraph 1,
In Formula 1, Ar ₁ is a composite membrane for a lithium battery selected from the group represented by Formula 3 below:
[Formula 3]

In Formula 3, * represents a binding region, and R ₁₁ to R ₁₉ are independently hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or It is a substituted C3-C30 heteroaryl group. According to paragraph 1,
of formula 1 A composite membrane for lithium batteries selected from the group represented by Formula 4 or Formula 4a:
[Formula 4]

In Formula 4, Z is S, N or P, and R ₁₁ to R ₂₅ are independently hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy group, or an unsubstituted group. Unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C3-C30 heteroaryloxy group, It is an unsubstituted or substituted C4-C30 cycloalkyl group or an unsubstituted or substituted C3-C30 heterocycloalkyl group,
However, if Z is S, R ₁₁ is absent.
[Formula 4a]

In Formula 4a, R ₂₂ to R ₂₆ are defined the same as R ₁₁ to R ₂₅ in Formula 4, and Z is N. According to paragraph 1,
of formula 1 is selected from the group represented by the following formula 5, and Y ^- in formula 1 is BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , CH ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , (FSO ₂ ) ₂ N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , and (O(CF ₃ ) ₂ C ₂ ( CF ₃ ) ₂ O) ₂ PO ^- Composite membrane for lithium battery containing one or more anions selected from:
[Formula 5]

In Formula 5, R ₂₀ to R ₂₈ are independently hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, Unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or substituted C4-C30 cyclo It is an alkyl group or an unsubstituted or substituted C3-C30 heterocycloalkyl group. delete According to paragraph 1,
A composite membrane for a lithium battery, wherein the composite membrane contains a lithium salt. In clause 7,
A composite membrane for a lithium battery in which the content of the lithium salt is 1 to 90 parts by weight based on 100 parts by weight of the total weight of the composite membrane. According to paragraph 1,
A composite membrane for a lithium battery wherein the degree of polymerization of the copolymer is 10 to 5,000. According to paragraph 1,
In Formula 1, m is 0.45 to 0.8. A composite membrane for a lithium battery. According to paragraph 1,
A composite membrane for a lithium battery wherein the copolymer is a copolymer represented by the following formula (6), and the degree of polymerization of the copolymer is 10 to 5,000:
[Formula 6]


In Formula 6, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group,
R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,
A simply represents a chemical bond or is an unsubstituted or substituted C1-C30 alkylene group, or an unsubstituted or substituted C6-C30 arylene group,
Y ^- is BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , CH ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , (FSO ₂ ) ₂ N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , and (O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- and one or more anions selected from ,
m and n are each 0.01 to 0.99 and their sum is 1,
R ₇ is hydrogen, an unsubstituted or substituted C1-C20 alkyl group, or an unsubstituted or substituted C6-C20 aryl group,
is a group represented by the following formula 4,
[Formula 5]

In Formula 5, R ₂₀ to R ₂₈ are independently hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, Unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or substituted C4-C30 cyclo It is an alkyl group or an unsubstituted or substituted C3-C30 heterocycloalkyl group, and * represents the binding region. According to paragraph 1,
A composite membrane for a lithium battery wherein the copolymer is at least one selected from compounds represented by Formula 6a, Formula 6b, Formula 6c, and Formula 6d:
[Formula 6a] [Formula 6b]

[Formula 6c] [Formula 6d]

Y ^- is PF ₆ ^{- ,} AsF ₆ ^- , SbF ₆ -, AlCl ₄ ^- , HSO ₄ ^- , CH ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , SO ₄ ^2- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , (FSO ₂ ) ₂ N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , CH ₃ COO ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , ( CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , and (O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- ,
a is an integer from 1 to 10,
R ₂₄ is an alkyl group of C1-C10.
m and n are each 0.01 to 0.99 and their sum is 1,
The degree of polymerization of the copolymer is a number from 10 to 5000. According to paragraph 1,
A composite membrane for a lithium battery having a thickness of 1 nm to 1000 μm. According to paragraph 1,
A composite membrane for a lithium battery wherein the copolymer has a weight average molecular weight of 3,000 Dalton to 400,000 Dalton. According to paragraph 1,
The composite membrane is a composite membrane for lithium batteries that maintains a free standing film at 25 to 60°C. According to paragraph 1,
A composite membrane for lithium batteries in which the copolymer is electrochemically stable up to -0.4V with respect to lithium. According to paragraph 1,
A composite membrane for a lithium battery, wherein the composite membrane has a lithium ion conductivity of 0.001 mS/cm or more at 25°C. anode;
cathode; and
A lithium battery comprising the composite membrane of any one of claims 1 to 5 and claims 7 to 17 interposed therebetween. According to clause 18,
the negative electrode is a lithium metal or lithium metal alloy electrode; or
The cathode is selected from carbon-based materials, silicon, silicon oxide, silicon-based alloys, silicon-carbon-based material composites, tin, tin-based alloys, tin-carbon composites, metals/metalloids alloyable with lithium, alloys thereof, or oxides thereof. A lithium battery containing one or more negative electrode active materials. According to clause 18,
A lithium battery in which the cathode is a lithium metal or lithium metal alloy electrode, and the composite film is a cathode protective film or a cathode protective film and electrolyte. According to clause 18,
The composite membrane is an electrolyte for a lithium battery. According to clause 18,
The lithium battery further includes one or more selected from a liquid electrolyte, a solid electrolyte, a gel electrolyte, and a polymer ionic liquid. According to clause 18,
A lithium battery whose operating voltage is 4.0V or higher. According to clause 18,
A lithium battery in which the positive electrode includes a positive electrode active material and a copolymer including a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2):
[Formula 1]

In Formula 1, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group,
R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,
A simply represents a chemical bond, or an unsubstituted or substituted C1-C30 alkylene group, an unsubstituted or substituted C6-C30 arylene group, an unsubstituted or substituted C3-C30 heteroarylene group, or an unsubstituted or substituted It is a C4-C30 cycloalkylene group, or an unsubstituted or substituted C3-C30 heterocycloalkylene group,
is a 3- to 31-membered ring containing 2 to 30 carbon atoms,
X is S, N, N(R) or P(R ^' ),
R and R ^' are independently of each other hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 heteroalkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C7-C30 arylalkyl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C4-C30 heteroarylalkyl group, unsubstituted or substituted C3-C30 cycloalkyl group, unsubstituted or substituted C2-C30 alkenyl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or A substituted C3-C30 heterocycloalkyl group or an unsubstituted or substituted C3-C30 alkynyl group,
Y ^- is an anion,
[Formula 2]

In Formula 2, R ₄ , R ₅ , and R ₆ are, regardless of each other, hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted It is a C3-C30 heteroaryl group,
R ₇ is hydrogen, an unsubstituted or substituted C1-C20 alkyl group,
Or an unsubstituted or substituted C6-C20 aryl group,
a is an integer from 1 to 10,
In Formulas 1 and 2, m and n are the mole fractions of the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2, respectively, and their sum is 1, which are respectively greater than 0 and less than 1. A positive electrode for a lithium battery made of a positive electrode active material and a random copolymer containing a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2):
[Formula 1]

In Formula 1, Ar ₁ is a substituted or unsubstituted C6-C30 arylene group or a substituted or unsubstituted C6-C30 heteroarylene group,
R ₁ , R ₂ and R ₃ , regardless of each other, are hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted C3-C30 heteroaryl. It's awesome,
A simply represents a chemical bond, or an unsubstituted or substituted C1-C30 alkylene group, an unsubstituted or substituted C6-C30 arylene group, an unsubstituted or substituted C3-C30 heteroarylene group, or an unsubstituted or substituted It is a C4-C30 cycloalkylene group, or an unsubstituted or substituted C3-C30 heterocycloalkylene group,
is a 3- to 31-membered ring containing 2 to 30 carbon atoms,
X is S, N, N(R) or P(R ^' ),
R and R ^' are independently of each other hydrogen, an unsubstituted or substituted C1-C30 alkyl group, an unsubstituted or substituted C1-C30 heteroalkyl group, an unsubstituted or substituted C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl group, unsubstituted or substituted C7-C30 arylalkyl group, unsubstituted or substituted C6-C30 aryloxy group, unsubstituted or substituted C3-C30 heteroaryl group, unsubstituted or substituted C4-C30 heteroarylalkyl group, unsubstituted or substituted C3-C30 cycloalkyl group, unsubstituted or substituted C2-C30 alkenyl group, unsubstituted or substituted C3-C30 heteroaryloxy group, unsubstituted or A substituted C3-C30 heterocycloalkyl group or an unsubstituted or substituted C3-C30 alkynyl group,
Y ^- is an anion,
[Formula 2]

In Formula 2, R ₄ , R ₅ , and R ₆ are, regardless of each other, hydrogen, an unsubstituted or substituted C1-C20 alkyl group, an unsubstituted or substituted C6-C20 aryl group, or an unsubstituted or substituted It is a C3-C30 heteroaryl group,
R ₇ is hydrogen, unsubstituted or substituted C1-C20 alkyl group, regardless of each other,
Or an unsubstituted or substituted C6-C20 aryl group,
a is an integer from 1 to 10,
In Formulas 1 and 2, m and n are the mole fractions of the repeating unit represented by Formula 1 and the repeating unit represented by Formula 2, respectively, and their sum is 1, which are greater than 0 and less than 1, respectively.