KR20230090004A - Electrolyte for secondary battery, manufacturing method thereof, and secondary battery comprising same - Google Patents

Abstract

[화학식 B]

상기 화학식 A 및 B에서 R1 내지 R6는 서로 동일하거나 상이하고 각각 독립적으로, 수소; 할로겐; 및 치환 또는 비치환된 탄소수 10 이내의 직쇄 또는 분지쇄로서, 알킬기, 시클로알킬기, 알케닐기, 시클로알케닐기, 알카이닐기, 아릴기, 헤테로아릴기, 아릴알킬기 및 아릴알케닐기; 중에서 선택된다. An electrolyte additive for a secondary battery according to an embodiment of the present invention is a compound containing at least one functional group selected from a functional group represented by the following Chemical Formula A and a functional group represented by the following Chemical Formula B:
[Formula A]

[Formula B]

In Formulas A and B, R1 to R6 are the same as or different from each other and are each independently hydrogen; halogen; and a substituted or unsubstituted straight chain or branched chain having up to 10 carbon atoms, including an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an arylalkyl group, and an arylalkenyl group; are selected from

Description

Electrolyte for secondary battery, manufacturing method thereof, and secondary battery comprising the same

The present invention relates to a novel electrolyte additive that can be added to an electrolyte for a secondary battery to improve the performance of a secondary battery, a method for preparing the same, and an electrolyte and a secondary battery including the same.

Batteries are used as power sources for portable electronic devices such as video cameras, mobile phones, and notebook computers. Rechargeable secondary batteries, especially lithium secondary batteries, have three times higher energy density per unit weight than conventional lead storage batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries, and can be charged at high speed.

Demand for such secondary batteries, particularly lithium secondary batteries, is rapidly increasing, and accordingly, a lot of research has been conducted on lithium secondary batteries having high energy density and discharge voltage, and they have been commercialized and widely used.

Compared to other batteries, lithium secondary batteries have advantages such as light weight, small volume, high operating voltage, high energy density, high output power, high charging efficiency, no memory effect, and long lifespan. It has been widely applied in the field of digital products such as mobile phones and laptops, and is considered one of the best choices for electric vehicles and large-scale energy storage devices.

Recently, as the development of medium and large-sized lithium secondary batteries such as electric vehicles is progressing, various studies are being conducted to realize high voltage and high capacity lithium secondary batteries. This is where additives are needed.

Republic of Korea Patent Publication No. 10-2019-0022382 Republic of Korea Patent Publication No. 10-2019-0063986 Republic of Korea Patent Publication No. 10-2020-0059535 Japanese Unexamined Patent Information No. 2016-192381

The present invention is intended to provide a novel electrolyte additive for secondary batteries capable of improving the performance of secondary batteries.

An object of the present invention is to provide an electrolyte additive for a secondary battery having excellent charge/discharge characteristics, output characteristics, capacity characteristics and voltage characteristics.

An electrolyte additive for a secondary battery according to an embodiment of the present invention is a compound including at least one functional group selected from a functional group represented by Chemical Formula A and a functional group represented by Chemical Formula B below.

[Formula A]

[Formula B]

In Formulas A and B, R1 to R6 are the same as or different from each other and are each independently hydrogen; halogen; and a substituted or unsubstituted straight chain or branched chain having up to 10 carbon atoms, including an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an arylalkyl group, and an arylalkenyl group; are selected from

As a preferred example, the electrolyte additive for a secondary battery may be a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, R1 to R6 are as described above in Formulas A and B.

As a preferred example, the electrolyte additive for a secondary battery may be a compound containing a functional group represented by Formula A-1 below.

[Formula A-1]

As a preferred example, the electrolyte additive for a secondary battery may be a compound containing a functional group represented by Formula B-1 below.

[Formula B-1]

As a preferred example, the electrolyte additive for a secondary battery may be a compound represented by Formula 1-1 below.

[Formula 1-1]

The method for preparing the electrolyte additive for a secondary battery according to an embodiment of the present invention includes adding O-(prop-2-yn-1-yl)1H-imidazole-1-carbothioate (0-(prop- Adding a morpholine compound to 2-yn-1-yl)1H-imidazole-1-carbothioate) and reacting in an organic solvent; removing a morpholine compound after completion of the reaction; and concentrating and recrystallizing the compound dissolved in the organic solvent.

As a more preferable example, in the reaction step, 1,8-diazabicyclo[5,4,0]undec-7-ene (1,8-Diazabicyclo[5.4.0]undec-7-ene, DUB) is introduced. may further include

An electrolyte for a secondary battery according to an embodiment of the present invention includes the electrolyte additive for a secondary battery.

As an example, the electrolyte additive for a secondary battery may be included in an amount of 0.1 to 10% by weight based on the total amount of the secondary battery electrolyte.

As an example, the electrolyte for the secondary battery may include a lithium salt; And a solvent; may further include.

A secondary battery according to an embodiment of the present invention includes a cathode including a cathode active material; A negative electrode containing a negative electrode active material; and the secondary battery electrolyte included between the positive electrode and the negative electrode.

The present invention provides an electrolyte additive for a secondary battery capable of improving the performance of a secondary battery and a manufacturing method thereof.

The present invention provides an electrolyte additive for a secondary battery having excellent charge/discharge characteristics, output characteristics, voltage characteristics and capacity characteristics, and a manufacturing method thereof.

Embodiments of the technical idea of the present invention may provide various effects not specifically mentioned.

The advantages and features of the present invention, and how to achieve them, will become clear with reference to the detailed description of the embodiments below. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms.

As used herein, “comprising” should be understood as an open-ended term that connotes the possibility of including other embodiments.

As used herein, “preferred” and “preferably” refer to embodiments of the invention that may provide certain advantages under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Additionally, the recitation of one or more preferred embodiments does not imply that the other embodiments are not useful, nor is it intended to exclude the other embodiments from the scope of the present invention.

An electrolyte additive for a secondary battery according to an embodiment of the present invention is a compound including at least one functional group selected from a functional group represented by Chemical Formula A and a functional group represented by Chemical Formula B below.

[Formula A]

[Formula B]

In Formulas A and B, R1 to R6 are the same as or different from each other and are each independently hydrogen; halogen; and a substituted or unsubstituted straight chain or branched chain having up to 10 carbon atoms, including an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an arylalkyl group, and an arylalkenyl group; are selected from

As used herein, "substituted or unsubstituted" refers to a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amino group, a phosphine oxide group, an alkoxy group, an aryloxy group, an alkylthioxy group, An arylthioxy group, an alkylsulfoxyl group, an arylsulfoxyl group, a silyl group, a boron group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an aralkenyl group, an alkylaryl group, an alkylamine group. It means substituted or unsubstituted with one or more substituents selected from the group consisting of an aralkylamine group, a heteroarylamine group, an arylamine group, an arylphosphine group, and a heterocyclic group.

The secondary battery may be a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, a lithium sulfur secondary battery, or an all-solid-state battery.

In addition, the electrolyte for the secondary battery may be a solid electrolyte, a gel electrolyte, and/or an electrolyte solution.

In addition, the electrolyte additive for a secondary battery may be a compound added as an additive to the electrolyte, and is a generic term for a compound introduced as a solvent of the electrolyte for a secondary battery.

As a more preferred embodiment, the electrolyte additive for a secondary battery may be a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, R1 to R6 are as described above in Formulas A and B.

As a more preferable example, the electrolyte additive for a secondary battery may be a compound including a functional group represented by Formula A-1 below.

[Formula A-1]

As a more preferable example, the electrolyte additive for a secondary battery may be a compound including a functional group represented by the following Chemical Formula B-1.

[Formula B-1]

As an example, the electrolyte additive for a secondary battery may be the following compound.

As a most preferable example, the electrolyte additive for a secondary battery may be a compound represented by Formula 1-1 below.

[Formula 1-1]

As an example, the compound represented by Chemical Formula 1-1 may be formed by a reaction according to Reaction Scheme 1- below.

[Scheme 1-1]

As an example, the method for preparing the electrolyte additive includes adding a morpholine compound to (0-(prop-2-yn-1-yl) 1H-imidazole-1-carbothioate) in a reactor and reacting it in an organic solvent. carry out

As an example, the compound can be used for both reagent and industrial purposes, and the lower the moisture content, the better, but it can be used by removing moisture at 100 to 2000 ppm, preferably 100 to 1000 ppm, and more preferably 100 to 300 ppm.

As an example, in the above reaction, 1 to 4 equivalents, preferably 1 to 3 equivalents, and more preferably 1 to 2 equivalents of each silane compound may be used with respect to 1 equivalent of morpholine.

As an example, the organic solvent may be at least one selected from ethylene chloride, dichloroethane, diethyl ether, diisopropyl ether, and toluene, and in addition, it may be synthesized in a water-immiscible lipophilic organic solvent, but is limited thereto it is not going to be

As an example, a solvent having a water content of 10 to 1000 ppm, preferably 10 to 700 ppm, and more preferably 10 to 300 ppm of the organic solvent may be used. If the moisture content is high, the starting material (0-(prop-2-yn-1-yl) 1H-imidazole-1-carbothioate) or morpholine is decomposed by moisture to produce impurities.

As an example, the reaction temperature may be -5 to 100 °C, preferably -5 to 80 °C, and more preferably -5 to 50 °C.

As an example, the reaction is preferably performed under a nitrogen atmosphere.

At this time, in the reaction step, 1,8-diazabicyclo[5,4,0]undec-7-ene (1,8-Diazabicyclo[5.4.0]undec-7-ene, DUB) is further added. can include

Next, a step of removing the morpholine compound produced after completion of the reaction is performed.

For example, when removing the morpholine compound, the morpholine compound may be removed through a water washing process.

For example, when the morpholine compound is removed, water is added dropwise to the reaction solution, and when the addition of the water is completed, an aqueous layer and a methylene chloride layer are separated from the reaction solution. Next, the methylene chloride layer may be washed with the same amount of water, and moisture in the methylene chloride layer may be removed with magnesium sulfate.

Next, after completion of the reaction, a step of concentrating and recrystallizing the compound dissolved in the organic solvent is performed.

When concentrating and recrystallizing the compound dissolved in the organic solvent, the solvent may be removed by concentration under reduced pressure, and crystals may be prepared by adding ether to the concentrated residue and crystallizing in an ice bath.

The electrolyte additive prepared and obtained by the manufacturing method according to an embodiment is 1H NMR analysis by hydrogen nuclear magnetic resonance spectroscopy (1H NMR spectroscopy), (1H 2.53ppm, 2H 3.67ppm, 2H 3.76ppm, 2H 3.79ppm, 2H 4.08ppm, 2H 5.14ppm) may indicate a peak (peak).

An electrolyte for a secondary battery according to an embodiment of the present invention includes the secondary battery electrolyte additive.

As an example, in the secondary battery electrolyte, the secondary battery electrolyte additive is 0.1 to 10% by weight, 0.1 to 5% by weight, 0.1 to 3% by weight, 0.1 to 1% by weight, 9 to 10% by weight, based on the total amount of secondary battery electrolytes. , 3 to 10% by weight, or 5 to 10% by weight.

As an example, the electrolyte for the secondary battery may include a lithium salt; And a solvent; may further include.

As an example, the lithium salt is LiPF ₆ , LiBF ₄ , LiB ₁₂ F ₁₂ , LiAsF ₆ , LiFSO ₃ , Li ₂ SiF ₆ , LiCF ₃ CO ₂ , LiCH ₃ CO ₂ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiCF ₃ CF ₂ SO ₃ , LiCF ₃ (CF ₂ ) ₇ SO ₃ , LiCF ₃ CF ₂ (CF ₃ ) ₂ CO, Li(CF ₃ SO ₂ ) ₂ CH, LiNO ₃ , LiN(CN) ₂ , LiN (FSO ₂ ) ₂ , LiN(F ₂ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiP(CF ₃ ) ₆ , LiPF(CF ₃ ) ₅ , LiPF ₂ (CF ₃ ) ₄ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₂ C ₂ O ₄ , LiBC ₄ O ₈ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ , LiSbF ₆ , LiAlO ₄ , LiAlF ₄ , LiSCN, LiClO ₄ , LiCl, LiF, LiBr, LiI, LiAlCl ₄ It may be any one or more selected, but It is not limited.

As an example, the solvent is preferably an organic solvent in which the electrolyte additive can be dissolved, and all solvents that can be commonly used in secondary batteries may be used, and are not particularly limited thereto. As an example, carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, or aprotic solvents may be used. In addition, as an embodiment, at least one or more of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) may be included.

In addition, the electrolyte for a secondary battery may further include another additive. As an example, the additive may be at least one selected from carbonate-based compounds, sultone-based compounds, and phosphazene-based compounds, but is not limited thereto.

A secondary battery according to an embodiment of the present invention includes a cathode including a cathode active material; A negative electrode containing a negative electrode active material; and the above-described secondary battery electrolyte included between the positive electrode and the negative electrode. In addition, a separator may be further included.

The secondary battery may be a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, a lithium sulfur secondary battery, or an all-solid-state battery, but is not limited thereto.

The cathode includes a current collector and a cathode active material layer formed on the current collector, and the cathode active material layer may further include a binder or a conductive material in addition to the cathode active material. The cathode active material is not particularly limited as long as it is a compound capable of intercalation and deintercalation of ions.

As an example, the cathode active material is LiNi _x Co _y Mn _z L _(1-xyz) O ₂ (0≤x≤1, 0≤y≤1, 0≤z≤1, and L is Al, Sr, Mg, At least one selected from Ti, Nb, V, Ca, Zr, Zn, Sn, Si and Fe), LiNi _x Co _y Al _z L _(1-xyz) O ₂ (0≤x≤1, 0≤y≤1 , 0≤z≤1 and L is at least one selected from Al, Sr, Mg, Ti, Nb, V, Ca, Zr, Zn, Sn, Si and Fe), wLi ₂ MnO ₃ (1-w)LiMn _a Ni _b Co _c L _(1-abc) O ₂ (0<w<1, 0≤a≤1, 0≤b≤1, 0≤c≤1, and L is Al, Sr, Mg, Ti, Nb , V, Ca, Zr, Zn, Sn, Si, Sb, and Fe), Li _1.2 Mn _0.8-a L _a O ₂ (0≤a≤0.8, and L is Al, Sr, Mg, Ca , Ti, V, Cr, Ni, Co, Fe, Cu, Nb, W, Zr, Zn, Sn, Sb, and Si), LiMPO ₄ (M is selected from Fe, Co, Ni, and Mn any one or more), LiMn _2-x M _x O ₄ (0≤x<1 and M is any one or more selected from Ni, Co, Fe, Cr, V, Ti, Nb, Cu, Sn, Sb, and Si), Li ₂ N _1-x M _x O ₃ (0≤x<1, N is at least one selected from Mn, Ni, Sn, Fe, Ru, and Ir, and M is Ti, Mn, Sn, Sb, Ru, and At least one selected from Te), and Li _1+x N _yz M _z O ₂ (0≤x≤1, N is any one or more selected from Ti and Nb, M is any one selected from V, Ti, Mo and W One or more) may be any one or more selected from, but is not limited thereto.

The negative electrode includes a current collector and a negative active material layer formed on the current collector, and the negative active material layer may further include a binder or a conductive material in addition to the negative active material.

The negative electrode active material is not particularly limited as long as it is a material capable of reversibly intercalating and deintercalating ions. As an example, a carbon-based or silicon-based negative electrode active material may be used.

When the secondary battery further includes a separator, the separator is a porous polymer film, for example, ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer. Porous polymer films made of polyolefin-based polymers may be used alone or by laminating them, or ordinary porous nonwoven fabrics such as high melting point glass fibers and polyethylene terephthalate fibers may be used, but are limited thereto. It is not.

As a more preferred example, the secondary battery may have a charge cut-off voltage of 4.0 to 6.0V.

The manufacturing method of the secondary battery is based on a known manufacturing method, and a detailed description thereof will be omitted.

Hereinafter, the present invention will be described in more detail through examples. Since these examples are intended to illustrate the present invention only, the scope of the present invention is not to be construed as being limited by these examples.

Preparation of O-(prop-2-yn-1-yl) morpholine-4-carbothioate

First, a magnetic bar and a thermometer are installed in a 500mL flask, and 25g of Morpholine is added. After adding 250 g of acetonitrile (ACN) with a water content of 100 ppm or less as a solvent and completely dissolving after stirring, O-(prop-2-yn-1-yl) 1H-imidazole-1-carbothioate (O- (prop-2-yn-1-yl)1H-imidazole-1-carbothioate) 51.67g was added and stirred. 7.14 g of Diazabicyclo (5.4.0) undec-7-ene (DBU) was added and the progress of the reaction was monitored through GC or TLC. After the overnight reaction, 500 ml of 1M HCl aqueous solution was added and quenched to complete the reaction. Then, EA (100gX3) is added to try extraction, and brine (100g) is added to the organic layer to wash again. The obtained organic layer was filtered after adding MgSO ₄ to remove moisture and concentrated under reduced pressure. 165 g of isopropyl ether is added to the concentrated target material to prepare O-(prop-2-yn-1-yl) morpholine-4-carbothioate crystals. At this time, the yield is about 80%. (1H 2.53ppm, 2H 3.67ppm, 2H 3.76ppm, 2H 3.79ppm, 2H 4.08ppm, 2H 5.14ppm)

Manufacture of Electrolyte

[Example]

1M LiPF ₆ was mixed in a solvent of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) at 30:70 (vol%), and O-(prop-2-yn-1-yl) morpholine-4 prepared above An electrolyte was prepared by adding 1% by weight of -carbothioa.

[Comparative Example]

An electrolyte solution was prepared in the same manner as in the above Example, except that O-(prop-2-yn-1-yl) morpholine-4-carbothioa was not added.

Manufacture of lithium secondary battery

<Manufacture of anode>

A ternary active material (Li(Ni _0.5 Mn _0.3 Co _0.2 )O ₂ ) as a cathode active material, carbon black as a conductive material, and polyvinylidene fluoride (as a binder) in 100 parts by weight of N-methyl-2-pyrrolidone (NMP). A positive active material slurry was prepared by adding 40 parts by weight of a solid content mixed with PVDF) in a ratio of 90:5:5 (wt%). The positive electrode active material slurry was applied to a positive electrode current collector (Al thin film) having a thickness of 100 μm, dried, and subjected to a roll press to prepare a positive electrode.

<Manufacture of cathode>

Solid content of NMP mixed with 100 parts by weight of natural graphite and SiO _x (0<x<1) as negative electrode active material, PVDF as binder, and carbon black as conductive material at a ratio of 90:5:2:3 (wt%) An anode active material slurry was prepared by adding 100 parts by weight. The negative electrode active material slurry was coated on a negative electrode current collector (Cu thin film) having a thickness of 90 μm, dried, and subjected to a roll press to prepare a negative electrode.

<Manufacture of lithium secondary battery>

An electrode assembly was prepared by laminating the prepared positive and negative electrodes together with a polyethylene porous film, and then placed in a pouch-type battery case, injected with the secondary battery electrolytes according to the above examples and comparative examples, respectively, and sealed.

[Experimental Example] Evaluation of capacity retention rate (%)

The prepared lithium secondary battery was charged at room temperature (1C charge up to 4.5V at 25°C, discharged at 2.75V 1C, then charged at 0.5C up to 4.2V at high temperature (1C charge up to 4.2V after leaving for 1 week at 45°C, discharged at 2.75V 1C). After 2 cycles, the capacity discharged in the 2nd cycle was measured and compared.

The battery characteristics of the lithium secondary battery according to the Examples and Comparative Examples are shown in Table 1 below.

Example comparative example Capacity retention rate (%) 87.9 82.8

Claims (11)

A compound containing at least one functional group selected from a functional group represented by the following formula A and a functional group represented by the following formula B,
Electrolyte additives for secondary batteries:
[Formula A]

[Formula B]

In Formulas A and B, R1 to R6 are the same as or different from each other, and each independently hydrogen; halogen; and a substituted or unsubstituted straight chain or branched chain having up to 10 carbon atoms, including an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an arylalkyl group, and an arylalkenyl group; are selected from
According to claim 1,
A compound represented by Formula 1 below,
Electrolyte additives for secondary batteries:
[Formula 1]

In Formula 1, R1 to R6 are as described above in Formulas A and B.
According to claim 1,
A compound containing a functional group represented by Formula A-1 below,
Electrolyte additives for secondary batteries:
[Formula A-1]

According to claim 1,
A compound containing a functional group represented by the following formula B-1,
Electrolyte additives for secondary batteries:
[Formula B-1]

According to claim 1,
A compound represented by Formula 1-1 below,
Electrolyte additives for secondary batteries:
[Formula 1-1]

In the method for producing the electrolyte additive for a secondary battery of claim 1,
Molar to O-(prop-2-yn-1-yl)1H-imidazole-1-carbothioate (0-(prop-2-yn-1-yl)1H-imidazole-1-carbothioate) in the reactor Injecting a porin (morpholine) compound and reacting under an organic solvent;
removing a morpholine compound after completion of the reaction; and
Concentrating and recrystallizing the compound dissolved in the organic solvent;
Method for manufacturing electrolyte additives for secondary batteries.
According to claim 6,
Further comprising introducing 1,8-diazabicyclo [5,4,0] undec-7-ene (DUB) in the reaction step,
Electrolyte additive manufacturing method for secondary battery.
Comprising the electrolyte additive for a secondary battery of claim 1,
Electrolyte for secondary batteries.
According to claim 8,
The electrolyte additive for secondary batteries is included in 0.1 to 10% by weight relative to the total electrolyte for secondary batteries,
Electrolyte additives for secondary batteries.
According to claim 8,
The electrolyte for the secondary battery may include a lithium salt; And a solvent; further comprising a,
Electrolyte for secondary batteries.
A cathode containing a cathode active material;
A negative electrode containing a negative electrode active material; and
Including, the electrolyte for a secondary battery of claim 8 included between the positive electrode and the negative electrode.
secondary battery.