WO2016053040A1 - Electrolyte additive for lithium secondary battery and non-aqueous electrolyte and lithium secondary battery comprising the electrolyte additive - Google Patents

Abstract

The present invention provides a non-aqueous electrolyte comprising: an additive which is an isocyanate-based compound comprising a non-aqueous organic solvent, a lithium salt, and a carbon-carbon triple bond; and the isocyanate-based compound comprising a carbon-carbon triple bond. In the case where the isocyanate-based compound additive comprising a carbon-carbon triple bond of the present invention is included in a non-aqueous electrolyte, lifespan properties and high temperature durability may be enhanced, and the internal resistance of a battery may be reduced.

Description

Electrolyte Additive for Lithium Secondary Battery, Non-Aqueous Electrolyte and Lithium Secondary Battery Containing the Electrolyte Additive

[Cross-cited with Related Applications]

This application claims the benefit of priority based on Korean Patent Application No. 10-2014-0133432 dated October 02, 2014 and Korean Patent Application No. 10-2015-0138640 dated October 01, 2015. All content disclosed in the literature is included as part of this specification.

[Technical Field]

The present invention relates to a secondary battery in which a non-aqueous electrolyte solution containing an isocyanate compound is included in a secondary battery, thereby improving life characteristics and high temperature durability.

As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing, and lithium secondary batteries having high energy density and voltage among these secondary batteries are commercially used and widely used.

Lithium metal oxide is used as a positive electrode active material of a lithium secondary battery, and lithium metal, a lithium alloy, crystalline or amorphous carbon or a carbon composite material is used as a negative electrode active material. The active material is applied to a current collector with a suitable thickness and length, or the active material itself is applied in a film shape to form an electrode group by winding or laminating together with a separator, which is an insulator, and then put it in a can or a similar container, and then injecting an electrolyte solution. A secondary battery is manufactured.

In such a lithium secondary battery, charging and discharging progress while repeating a process of intercalating and deintercalating lithium ions from a lithium metal oxide of a positive electrode to a graphite electrode of a negative electrode. At this time, lithium is highly reactive and reacts with the carbon electrode to generate Li ₂ CO ₃ , LiO, LiOH and the like to form a film on the surface of the negative electrode. Such a film is called a solid electrolyte interface (SEI) film, and the SEI film formed at the beginning of charging prevents the reaction between lithium ions and a carbon anode or other material during charging and discharging. It also acts as an ion tunnel, allowing only lithium ions to pass through. The ion tunnel serves to prevent the organic solvents of a large molecular weight electrolyte which solvates lithium ions and move together and are co-intercalated with the carbon anode to decay the structure of the carbon anode.

Therefore, in order to improve the high temperature cycle characteristics and the low temperature output of the lithium secondary battery, a solid SEI film must be formed on the negative electrode of the lithium secondary battery. Once formed, the SEI membrane prevents the reaction between lithium ions and the negative electrode or other materials during repeated charge / discharge cycles, and serves as an ion tunnel that passes only lithium ions between the electrolyte and the negative electrode. Will be performed.

Conventionally, in the case of an electrolyte solution containing no electrolyte additive or an electrolyte additive having poor properties, it is difficult to expect an improvement in battery life due to the formation of a non-uniform SEI film. Furthermore, even when it contains an electrolyte additive, when the input amount is not adjusted to the required amount, the electrolyte additive may decompose the surface of the anode during the high temperature reaction or the electrolyte may oxidize, resulting in an increase in the irreversible capacity of the secondary battery and There was a problem that durability is lowered.

The present invention aims to solve the technical problem that has been requested from the past as described above.

The inventors of the present application have confirmed that the output characteristics and stability are improved when the isocyanate compound additive including the carbon-carbon-triple bond in the nonaqueous electrolyte is improved in the electrolyte solution, and completed the present invention.

In order to solve the above problems, the present invention comprises a non-aqueous organic solvent, a lithium salt and an additive, the additive provides a non-aqueous electrolyte solution is an isocyanate compound containing a carbon-carbon triple bond.

The isocyanate compound including the carbon-carbon triple bond may include one or more selected from the group consisting of compounds represented by the following Chemical Formulas 1 to 3.

[Formula 1]

[Formula 2]

[Formula 3]

In Formula 3, R may be a linear or cyclic alkylene group, or an aromatic hydrocarbon group.

The isocyanate compound including the carbon-carbon triple bond may be included in an amount of 0.05 to 2 wt% based on the total weight of the nonaqueous electrolyte.

The lithium salt is LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (FSO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₆ , LiSbF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ , LiAlCl ₄ , LiSO ₃ CF ₃ and LiClO ₄ , any one selected from the group consisting of or a mixture of two or more thereof. The non-aqueous organic solvent is a nitrile solvent, linear carbonate, cyclic carbonate, ester, ether, Ketone or combinations thereof.

Lithium secondary battery according to the present invention by including an isocyanate compound containing a carbon-carbon triple bond in the non-aqueous electrolyte, it is possible to improve the output characteristics and stability of the resulting secondary battery.

1 is a graph showing the results of measuring the thickness increase after high-temperature storage of the secondary battery prepared in Examples 1 to 4, and Comparative Example 1.

Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The non-aqueous electrolyte according to an embodiment of the present invention may include an additive which is an isocyanate compound including a non-aqueous organic solvent, a lithium salt, and a carbon-carbon triple bond.

The isocyanate compound is a compound having a structure capable of easily reacting with an electrode surface in a thin film state and coordinating Li ions in structure, and specifically, the isocyanate compound is selected from compounds represented by the following Chemical Formulas 1 to 3 It may be to include one or more.

[Formula 1]

[Formula 2]

[Formula 3]

In Formula 3, R may be a linear or cyclic alkylene group, or an aromatic hydrocarbon group.

More specifically, R may be a hydrocarbon group excluding two isocyanate groups from one compound selected from the group consisting of compounds represented by the following Chemical Formulas 4 to 7.

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

The additive according to an embodiment of the present invention may form a homogeneous film in the electrolyte by having a -OH group-friendly property on the surface of the positive electrode or the negative electrode. More specifically, the + charge of the isocyanate group nitrogen (N) portion of the isocyanate compound is bonded to the —OH group on the surface of the positive or negative electrode. Accordingly, the additive of the isocyanate compound according to the embodiment of the present invention may form a stable SEI film on the electrode surface.

In particular, the carbon-carbon triple bond, which is one of the functional groups of the isocyanate compound, is capable of forming a stable film through a reduction reaction, and in the case of a portion in which the reduction reaction is small, the SEI is stable by reacting with an -OH group on the electrode surface through an isocyanate group. A film can be formed. That is, the compound including the carbon-carbon triple bond and the isocyanate group at the same time according to an embodiment of the present invention can be complemented to form a film on the electrode surface more efficiently.

Here, the isocyanate compound additive may be included in the 0.05 to 2% by weight based on the total weight of the non-aqueous electrolyte. When the content of the isocyanate compound is less than 0.05% by weight, the effect of improving the life characteristics and the high temperature durability according to an embodiment of the present invention is low, and when it exceeds 2% by weight, the possibility of gas generation at high temperature is increased.

In addition, the non-aqueous electrolyte according to one embodiment of the present invention may further include a heterogeneous additive. In particular, the non-aqueous electrolyte may further include a solid electrolyte interface (SEI) forming additive which is generally well known to suit the purpose. For example, in order to improve life, additives such as vinylene carbonate, vinyl ethylene carbonate, 1,3-propenesultone, 1,3-propanesultone, succinyl anhydride, lactam and caprolactam It may further include. In addition, cyclic nuclear chamber benzene, biphenyl, para chlorobenzene may be further included to improve overcharge. Such additives are not limited to the above examples, and in addition, various kinds of negative electrode and positive electrode film forming additives may be further added to the electrolyte in order to improve battery performance.

The lithium salt is, for example, LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (FSO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₆ , LiSbF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ , LiAlCl ₄ , LiSO ₃ CF ₃ and LiClO ₄ may be any one selected from the group consisting of or a mixture of two or more thereof.

As the non-aqueous organic solvent that can be included in the non-aqueous electrolyte solution, there is no limitation as long as it can minimize decomposition by an oxidation reaction or the like in the process of charging and discharging the battery, and can exhibit desired properties with an additive, for example Nitrile solvents, cyclic carbonates, linear carbonates, esters, ethers or ketones and the like. These may be used alone, or two or more thereof may be used in combination.

Carbonate-based organic solvents of the organic solvents can be easily used, the cyclic carbonate is any one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC) or two of them A mixture of two or more species, the linear carbonate consists of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC) It may be any one selected from the group or a mixture of two or more thereof.

The nitrile solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile and 4-fluorobenzonitrile , Difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile may be one or more selected from the group consisting of, one embodiment of the present invention Acetonitrile may be used as the non-aqueous solvent according to the example.

According to another embodiment of the present invention, a cathode, an anode, and a separator include a non-aqueous electrolyte solution containing the isocyanate compound, and at least one of the cathode or the anode is characterized in that the SEI film is formed on the surface. It may be a secondary battery.

The SEI film is a hydroxyl group (R) on the surface of the negative electrode or the positive electrode in a process in which an isocyanate compound having a carbon-carbon triple bond included in the electrolyte is subjected to an initial charge / discharge process or injected into the electrolyte in a secondary battery. '-OH) and nitrogen (N) of the isocyanate compound of the non-aqueous electrolyte solution may be formed by a urethane bond or an electrostatic force, or may be formed through a reduction reaction of a carbon-carbon triple bond which is a functional group of the isocyanate compound. have.

The positive electrode may be formed by applying a positive electrode mixture on a positive electrode current collector and dried, and the negative electrode may be formed by applying a negative electrode mixture on a negative electrode current collector and then drying.

Specifically, the positive electrode current collector is not particularly limited as long as it has a high conductivity without causing chemical change in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or the surface of aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver, or the like can be used. In this case, the positive electrode current collector may use various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric having fine irregularities formed on a surface thereof so as to increase the adhesion with the positive electrode active material.

In addition, the negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the negative electrode current collector may be formed on a surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper, or stainless steel. Surface-treated with carbon, nickel, titanium, silver and the like, aluminum-cadmium alloy and the like can be used. In addition, the negative electrode current collector, like the positive electrode current collector, may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric having fine irregularities formed on a surface thereof.

In addition, in the positive electrode or the negative electrode of the present invention, the positive electrode or negative electrode mixture may include an oxide containing at least one hydroxyl group (-OH) group, which can be used in the production of a typical positive electrode or negative electrode for secondary batteries.

Specifically, in the positive electrode mixture, the oxide is composed of lithium cobalt-based oxide, lithium manganese-based oxide, lithium copper oxide, vanadium oxide, lithium nickel-based oxide and lithium manganese composite oxide, lithium-nickel-manganese-cobalt-based oxide Any one lithium transition metal oxide selected from the group, more specifically Li _{1 + x} Mn _{2 -x} O ₄ , wherein x is 0 to 0.33, LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ Lithium manganese oxides such as; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Lithium nickel oxide represented by LiNi _1-x M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3; LiMn _{2 - x} M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ , where M = Fe, Co, Ni , Lithium manganese composite oxide, Li (Ni _a Co _b Mn _c ) O ₂ , where 0 <a <1, 0 <b <1, 0 <c <1, a + b Lithium-nickel-manganese-cobalt-type oxide etc. which are represented by + c = 1) are mentioned, However, It is not limited to these.

In the case of the negative electrode mixture, the oxide is selected from the group consisting of lithium-containing titanium composite oxide (LTO) or Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe, which can easily occlude and release lithium ions. Any one selected metal (Me) oxide (MeOx) and the like, specifically Li _x Fe ₂ O ₃ (0 = x = 1), Li _x WO ₂ (0 <x = 1), Sn _x Me _{1 - x} Me _'y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, of the periodic table Group 1, Group 2, Group 3 element, halogens; 0 <x = 1; 1 metal composite oxides such as = y = 3 and 1 = z = 8); SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ and An oxide such as Bi ₂ O ₅ may be used, and a carbon-based negative active material such as crystalline carbon, amorphous carbon or a carbon composite may be used alone or in combination of two or more thereof. In one embodiment of the present invention, a carbon powder This can be used.

In this case, the positive or negative electrode mixture may further include a binder resin, a conductive material, a filler and other additives.

The binder resin is a component that assists the bonding of the electrode active material and the conductive material and the bonding to the current collector, and is generally added in an amount of 1 to 50 wt% based on the total weight of the electrode mixture. Examples of such binder resins include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetra Fluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluorine rubber, various copolymers thereof, and the like.

The conductive material is a component for further improving the conductivity of the electrode active material, and may be added in an amount of 1 to 20 wt% based on the total weight of the electrode mixture. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Polyphenylene derivatives and the like can be used.

The filler is optionally used as a component for inhibiting the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples of the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.

The separator is a conventional porous polymer film conventionally used as a separator, for example, polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer The porous polymer film prepared by using a single or a lamination thereof may be used, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting glass fibers, polyethylene terephthalate fibers, etc. may be used, but is not limited thereto. .

Example

Example 1

(Non-aqueous electrolyte solution preparation)

Ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) = 3: 3: 4 non-aqueous organic solvent having a composition by weight (weight ratio) and lithium salt LiPF ₆ based on the total amount of the non-aqueous electrolyte The non-aqueous electrolyte was prepared by adding 1.0 mol / L and adding 0.5% by weight of the compound represented by Formula 1 as an additive based on the total amount of the non-aqueous electrolyte.

(Anode manufacturing)

94% by weight of Li (Ni _0.6 Co _0.2 Mn _0.2 ) O ₂ as a positive electrode active material, 3% by weight carbon black as a conductive agent, and 3% by weight binder PVdF were added to N-methyl-2 pyrrolidone (NMP) as a solvent to prepare a positive electrode mixture. A slurry was prepared, and the cathode mixture slurry was applied to an aluminum (Al) thin film, which is a positive electrode current collector having a thickness of 20 μm, and dried to prepare a cathode including pores.

(Cathode production)

A negative electrode mixture slurry was prepared by adding 95.5% by weight of carbon powder, 1.5% by weight of Super-P (conductor) and 3% by weight of SBR / CMC (binder) as the negative electrode active material to H ₂ O. It was coated on both sides of the copper foil, dried and pressed to prepare a negative electrode.

(Battery assembly)

After assembling a separator consisting of the cathode electrode, the anode electrode and the three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP) prepared as described above in a stacking manner, the prepared electrolyte is injected and finally The battery was completed.

Example 2

As a non-aqueous electrolyte additive, a secondary battery was completed in the same manner as in Example 1 except for using an isocyanate compound composed of Formula 2 instead of the compound represented by Formula 1.

Example 3

As a non-aqueous electrolyte additive, a secondary battery was completed in the same manner as in Example 1, except that R isocyanate compound composed of Formula 4 instead of compound represented by Formula 1 above.

Example 4

As a non-aqueous electrolyte additive, a secondary battery was completed in the same manner as in Example 1 except that 0.3 wt% of the compound represented by Chemical Formula 1 and 1 wt% of vinylene carbonate were used.

Comparative Example 1

A secondary battery was completed in the same manner as in Example 1 except that the additive was not included in the non-aqueous electrolyte.

Experimental Example 1

<Capacity Characterization>

The secondary batteries prepared in Examples 1 to 4 and Comparative Example 1 were charged at 1 C up to 4.15 V / 38 mA under constant current / constant voltage (CC / CV) conditions, and then discharged at 1 C up to 2.5 V under constant current (CC) conditions. The discharge capacity was measured. The results are shown in Table 1 below.

Experimental Example 2

<Discharge resistance measurement using HPPC>

HPPC (hybrid pulse power characterization) test was performed to measure the resistance of the secondary batteries prepared in Examples 1 to 4, and Comparative Example 1. Charge to full charge (SOC = 100) up to 4.15V at 1 C (30 mA), discharge the cells from SOC 100 to 10, stabilize the cells for 1 hour each, and then follow the HPPC test method for each SOC step. The discharge resistance of the lithium secondary battery was measured. The results are shown in Table 1 together.

Experimental Example 3

<Measurement of battery thickness increase rate>

The thicknesses of the secondary batteries prepared in Examples 1 to 4 and Comparative Example 1 were measured, and the thicknesses after storage for 1 week and 2 weeks at 60 ° C. were measured.

Initial capacity (mAh) Discharge resistance (mΩ) Example 1 748 48 Example 2 745 49 Example 3 744 52 Example 4 746 50 Comparative Example 1 745 54

Referring to Table 1 above, the lithium secondary batteries of Examples 1 to 4 including a non-aqueous electrolyte solution containing an isocyanate compound containing a carbon-carbon triple bond of the present invention as an additive are compared without the additive. It can be seen that the discharge resistance is lower than that of the lithium secondary battery of Example 1.

In addition, referring to Figure 1, the lithium secondary battery of Examples 1 to 4 including a non-aqueous electrolyte containing an isocyanate compound containing a carbon-carbon triple bond of the present invention as an additive, the thickness of the secondary battery The increase was small, especially when the high temperature storage period reached two weeks, the difference in thickness increase was more pronounced, and when the isocyanate compound including carbon-carbon triple bond was included as an additive, the high temperature storage property of the lithium secondary battery It can be seen that this improvement can reduce the increase in thickness after high temperature storage.

Claims (10)

Non-aqueous organic solvents, lithium salts and additives, The additive is a non-aqueous electrolyte solution is an isocyanate compound containing a carbon-carbon triple bond. The method of claim 1, The isocyanate compound containing the carbon-carbon triple bond is a non-aqueous electrolyte solution containing at least one selected from compounds represented by the following formulas (1) to (3). [Formula 1]

[Formula 2]

[Formula 3]

(In Formula 3, R is a linear or cyclic alkylene group or aromatic hydrocarbon group.) The method of claim 2, R of the compound represented by Formula 3 is a non-aqueous electrolyte solution, except for two isocyanate groups in one kind selected from the group consisting of compounds represented by the following formulas (4) to (7). [Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

The method of claim 1, The lithium salt is LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (FSO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₆ , LiSbF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ Non-aqueous electrolyte solution containing any one selected from the group consisting of LiAlCl ₄ , LiSO ₃ CF ₃ and LiClO ₄ or a mixture of two or more thereof. The method of claim 1, The non-aqueous organic solvent comprises a nitrile-based solvent, linear carbonate, cyclic carbonate, ester, ether, ketone or a combination thereof. The method of claim 5, wherein The cyclic carbonate is any one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC) or a mixture of two or more thereof, and the linear carbonate is dimethyl carbonate (DMC) or diethyl carbonate. (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate (EPC) any one selected from the group consisting of or a mixture of two or more thereof. The method of claim 5, wherein The nitrile solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile and 4-fluorobenzonitrile And at least one non-aqueous electrolyte solution selected from the group consisting of difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile. The method of claim 1, Isocyanate compound containing the carbon-carbon triple bond is a non-aqueous electrolyte containing 0.05 to 2% by weight based on the total weight of the non-aqueous electrolyte. A cathode, an anode, a separator and a non-aqueous electrolyte, The non-aqueous electrolyte is any one of the non-aqueous electrolyte according to claim 1, At least one of the negative electrode or the positive electrode is a lithium secondary battery is formed with a SEI film on the surface. The method of claim 9, The SEI film has a hydroxyl group (R'-OH) on the surface of the cathode or anode and nitrogen (N) of an isocyanate compound including a carbon-carbon triple bond of the nonaqueous electrolyte solution by a urethane bond or electrostatic attraction. A lithium secondary battery that is formed or formed through a reduction reaction of a carbon-carbon triple bond, which is a functional group of the isocyanate compound.

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