WO2024039232A1 - Batterie secondaire au lithium - Google Patents

Batterie secondaire au lithium Download PDF

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Publication number
WO2024039232A1
WO2024039232A1 PCT/KR2023/012295 KR2023012295W WO2024039232A1 WO 2024039232 A1 WO2024039232 A1 WO 2024039232A1 KR 2023012295 W KR2023012295 W KR 2023012295W WO 2024039232 A1 WO2024039232 A1 WO 2024039232A1
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Prior art keywords
group
formula
additive
lithium
secondary battery
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PCT/KR2023/012295
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English (en)
Korean (ko)
Inventor
조윤교
이철행
이경미
이정민
김은비
지수현
염철은
한정구
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주식회사 엘지에너지솔루션
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Priority claimed from KR1020230108361A external-priority patent/KR20240025491A/ko
Publication of WO2024039232A1 publication Critical patent/WO2024039232A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to lithium secondary batteries.
  • lithium secondary batteries Recently, the application area of lithium secondary batteries has rapidly expanded not only to supply power to electronic devices such as electricity, electronics, communication, and computers, but also to supply power storage to large-area devices such as automobiles and power storage devices, leading to high capacity, high output, and high stability. Demand for secondary batteries is increasing.
  • the lithium secondary battery largely consists of a positive electrode composed of a transition metal oxide containing lithium, a negative electrode capable of storing lithium, an electrolyte that serves as a medium for transferring lithium ions, and a separator.
  • the negative electrode may include a negative electrode active material such as a carbon-based active material or a silicon-based active material.
  • a film (SEI film) is formed on the anode and/or cathode during the initial activation process, which protects the anode and cathode during battery operation and prevents electrolyte consumption due to electrolyte side reactions. If a solid electrode film is not formed on the anode and/or cathode in this initial activation process, problems such as capacity degradation and reduced lifespan may result.
  • silicon-based active materials are attracting attention because they exhibit higher capacity than carbon-based active materials, but they have the disadvantage of being subject to large volume changes due to lithium insertion and desorption.
  • This volume expansion of the silicon-based active material reduces the durability of the already formed SEI film, or causes many problems such as continuous electrolyte consumption and increased thickness of the SEI film due to the generation of a new anode active material surface, which causes capacity degradation and reduced lifespan. I order it.
  • One object of the present invention is to provide a lithium secondary battery that can reduce electrolyte side reactions and improve high-temperature cycle life performance and high-temperature storage performance by forming a flexible and durable film on a negative electrode containing a silicon-based active material. .
  • the present invention is a cathode; an anode opposite the cathode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte; wherein the negative electrode includes a negative electrode active material, the negative electrode active material includes a silicon-based active material, the non-aqueous electrolyte includes a lithium salt, an organic solvent, and an additive, and the additive includes a first additive and an additive.
  • the first additive includes a compound represented by the following formula (1)
  • the second additive includes lithium fluoromalonato(difluoro)borate (LiFMDFB), lithium difluoro(oxalato) )
  • LiFMDFB lithium fluoromalonato(difluoro)borate
  • LiDFOP lithium difluorobis-(oxalate) phosphate
  • R is independently halogen, nitrile group, propargyl group, ester group, ether group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted group.
  • n is an integer selected from 0 to 6.
  • the lithium secondary battery according to the present invention is a negative electrode containing a silicon-based active material, a first additive containing a coumarin-based compound having a specific structural formula as an additive, and lithium fluoromalonato(difluoro)borate (LiFMDFB) and lithium difluoro. It is characterized by comprising a non-aqueous electrolyte containing a second additive containing (oxalato)borate (LiDFOB), etc.
  • a flexible, highly resilient, and durable SEI film can be formed on the cathode.
  • the lithium secondary battery according to the present invention has a large degree of volume expansion and forms the above-described SEI film on the silicon-based negative electrode, which is likely to cause electrolyte side reactions, thereby preventing cracking of the SEI film, preventing electrolyte side reactions, and increasing the thickness of the electrode film.
  • the overall performance of the lithium secondary battery especially high-temperature cycle life performance and high-temperature storage performance, can be improved.
  • alkyl group having 1 to 5 carbon atoms refers to an alkyl group containing 1 to 5 carbon atoms, i.e. CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, (CH 3 ) 2 CH -, CH 3 CH 2 CH 2 CH 2 -, (CH 3 ) 2 CHCH 2 -, CH 3 CH 2 CH 2 CH 2 -, (CH 3 ) 2 CHCH 2 CH 2 -, etc.
  • substitution means that at least one hydrogen bonded to carbon is replaced with an element other than hydrogen, for example, an alkyl group with 1 to 20 carbon atoms, an alkene with 2 to 20 carbon atoms.
  • Nyl group alkynyl group of 2 to 20 carbon atoms, alkoxy group of 1 to 20 carbon atoms, cycloalkyl group of 3 to 12 carbon atoms, cycloalkenyl group of 3 to 12 carbon atoms, cycloalkynyl group of 3 to 12 carbon atoms, hetero group of 3 to 12 carbon atoms Cycloalkyl group, heterocycloalkenyl group with 3 to 12 carbon atoms, aryloxy group with 6 to 12 carbon atoms, halogen atom, fluoroalkyl group with 1 to 20 carbon atoms, nitro group, aryl group with 6 to 20 carbon atoms, 2 to 20 carbon atoms It means substituted with a heteroaryl group, a haloaryl group having 6 to 20 carbon atoms, etc.
  • the present invention relates to lithium secondary batteries.
  • the lithium secondary battery according to the present invention includes a negative electrode; an anode opposite the cathode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte; wherein the negative electrode includes a negative electrode active material, the negative electrode active material includes a silicon-based active material, the non-aqueous electrolyte includes a lithium salt, an organic solvent, and an additive, and the additive includes a first additive and an additive.
  • the first additive includes a compound represented by the following formula (1)
  • the second additive includes lithium fluoromalonato(difluoro)borate (LiFMDFB), lithium difluoro(oxalato) ) Borate (LiDFOB), lithium difluorophosphate (LiDFP), and lithium difluorobis-(oxalate) phosphate (LiDFOP).
  • R is independently halogen, nitrile group, propargyl group, ester group, ether group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted group.
  • n is an integer selected from 0 to 6.
  • the lithium secondary battery according to the present invention is a negative electrode containing a silicon-based active material, a first additive containing a coumarin-based compound having a specific structural formula as an additive, and lithium fluoromalonato(difluoro)borate (LiFMDFB) and lithium difluoro. It is characterized by comprising a non-aqueous electrolyte containing a second additive containing (oxalato)borate (LiDFOB), etc.
  • a flexible, highly resilient, and durable SEI film can be formed on the cathode.
  • the lithium secondary battery according to the present invention has a large degree of volume expansion and forms the above-described SEI film on the silicon-based negative electrode, which is likely to cause electrolyte side reactions, thereby preventing cracking of the SEI film, preventing electrolyte side reactions, and increasing the thickness of the electrode film.
  • the overall performance of the lithium secondary battery especially high-temperature cycle life performance and high-temperature storage performance, can be improved.
  • the lithium secondary battery of the present invention can be manufactured according to a common method known in the art.
  • the cathode, the anode, and the separator between the cathode and the anode are sequentially stacked to form an electrode assembly, then the electrode assembly is inserted into the battery case and the non-aqueous electrolyte according to the present invention is injected to produce it. You can.
  • the negative electrode includes a negative electrode active material.
  • the negative electrode active material includes a silicon-based active material.
  • the silicon-based active material has the advantage of having a high capacity and high energy density compared to carbon-based active materials such as graphite, but has the disadvantage of a large change in the volume of the active material during charging and discharging.
  • the volume expansion and contraction of the silicon-based active material causes the conductive connection in the cathode to be broken, resulting in increased resistance and decreased lifespan performance.
  • the SEI film of the negative electrode formed during the activation process of a lithium secondary battery may be broken due to a change in the volume of the silicon-based active material, which promotes electrolyte side reactions, causing problems such as increased resistance due to increased SEI film thickness and electrolyte depletion. As a result, performance in life performance and storage characteristics may deteriorate.
  • the present invention is characterized by using a non-aqueous electrolyte using a combination of a first additive and a second additive, which will be described later, as additives, together with a negative electrode containing a silicon-based active material.
  • a first additive and a second additive which will be described later, as additives
  • the SEI film formed on the cathode can improve flexibility (recoverability) and durability at the same time, and has excellent recovery from volume changes of the silicon-based active material, and prevents the SEI film from breaking.
  • electrolyte side reactions and electrolyte depletion problems can be prevented to a significant level, making it possible to implement a lithium secondary battery with excellent lifespan performance and storage performance.
  • the average particle diameter (D 50 ) of the silicon-based active material may be 1 ⁇ m to 30 ⁇ m, preferably 2 ⁇ m to 15 ⁇ m in terms of reducing side reactions with the electrolyte while ensuring structural stability during charging and discharging.
  • the negative electrode active material may further include a carbon-based active material in addition to the silicon-based active material.
  • the carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably consists of artificial graphite and natural graphite. It may include at least one species selected from the group.
  • the average particle diameter (D 50 ) of the carbon-based active material may be 10 ⁇ m to 30 ⁇ m, preferably 15 ⁇ m to 25 ⁇ m, in terms of ensuring structural stability during charging and discharging and reducing side reactions with the electrolyte.
  • the weight ratio of the silicon-based active material and the carbon-based active material is 1:99 to 50:50, specifically 3:97 to 20:80, and more specifically 3:97 to 10. :Could be 90.
  • the negative electrode active material may not include a carbon-based active material.
  • the negative electrode includes a negative electrode current collector; and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. At this time, the negative electrode active material may be included in the negative electrode active material layer.
  • the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery.
  • the negative electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. there is.
  • the negative electrode current collector may typically have a thickness of 3 to 500 ⁇ m.
  • the negative electrode current collector may form fine irregularities on the surface to strengthen the bonding force of the negative electrode active material.
  • the negative electrode current collector may be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics.
  • the negative electrode active material layer is disposed on at least one side of the negative electrode current collector. Specifically, the negative electrode active material layer may be disposed on one or both sides of the negative electrode current collector.
  • the negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight, preferably 75% to 95% by weight.
  • the negative electrode active material layer may further include a binder and/or a conductive material along with the negative electrode active material.
  • the binder is used to improve battery performance by improving adhesion between the negative electrode active material layer and the negative electrode current collector, for example, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co- HFP), polyvinylidenefluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, recycled Cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoroelastomer, and hydrogen thereof. It may include at least one selected from the group consisting of substances substituted with Li, Na, or Ca, and may also include various copolymers thereof.
  • PVDF-co- HFP polyvinylidene flu
  • the binder may be included in the negative electrode active material layer in an amount of 0.5% to 30% by weight, preferably 1% to 15% by weight, and more preferably 5% to 10% by weight.
  • the conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery.
  • graphite such as natural graphite or artificial graphite
  • Carbon black such as acetylene black, Ketjen black, channel black, Paneth black, lamp black, and thermal black
  • Conductive fibers such as carbon fiber and metal fiber
  • Conductive tubes such as carbon nanotubes
  • fluorocarbon Metal powders such as aluminum and nickel powder
  • Conductive whiskers such as zinc oxide and potassium titanate
  • Conductive metal oxides such as titanium oxide
  • Conductive materials such as polyphenylene derivatives may be used.
  • the conductive material may be included in the negative electrode active material layer in an amount of 0.5% to 30% by weight, preferably 1% to 25% by weight.
  • the thickness of the negative electrode active material layer may be 10 ⁇ m to 100 ⁇ m, preferably 50 ⁇ m to 80 ⁇ m.
  • the negative electrode may be manufactured by coating at least one surface of a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and/or a solvent for forming a negative electrode slurry, followed by drying and rolling.
  • the solvent for forming the negative electrode slurry is, for example, distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol in terms of facilitating dispersion of the negative electrode active material, binder, and/or conductive material. It may contain at least one selected from the group, preferably distilled water.
  • the anode faces the cathode.
  • the positive electrode includes a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery.
  • the positive electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy, preferably aluminum.
  • the thickness of the positive electrode current collector may typically range from 3 to 500 ⁇ m.
  • the positive electrode current collector may form fine irregularities on the surface to strengthen the bonding force of the positive electrode active material.
  • the positive electrode current collector may be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.
  • the positive electrode active material layer is disposed on at least one side of the positive electrode current collector. Specifically, the positive electrode active material layer may be disposed on one or both sides of the positive electrode current collector.
  • the positive electrode active material layer may include a positive electrode active material.
  • the positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, a lithium transition metal complex oxide containing lithium and at least one transition metal consisting of nickel, cobalt, manganese, and aluminum, Preferably, it may include a transition metal containing nickel, cobalt, and manganese, and a lithium transition metal complex oxide containing lithium.
  • the lithium transition metal complex oxide includes lithium-manganese oxide (e.g., LiMnO 2 , LiMn 2 O 4 , etc.), lithium-cobalt oxide (e.g., LiCoO 2 , etc.), and lithium-nickel.
  • lithium-manganese oxide e.g., LiMnO 2 , LiMn 2 O 4 , etc.
  • lithium-cobalt oxide e.g., LiCoO 2 , etc.
  • lithium-nickel lithium-nickel
  • lithium-nickel-manganese oxide for example, LiNi 1-Y Mn Y O 2 (where 0 ⁇ Y ⁇ 1), LiMn 2-z Ni z O 4 (here, 0 ⁇ Z ⁇ 2), etc.
  • lithium-nickel-cobalt-based oxide for example, LiNi 1-Y1 Co Y1 O 2 (here, 0 ⁇ Y1 ⁇ 1), etc.
  • lithium-manganese -Cobalt-based oxides for example, LiCo 1-Y2 Mn Y2 O 2 (where 0 ⁇ Y2 ⁇ 1), LiMn 2-z1 Co z1 O 4 (where 0 ⁇ Z1 ⁇ 2), etc.
  • the lithium transition metal composite oxide is LiCoO 2 , LiMnO 2 , LiNiO 2 , lithium nickel-manganese-cobalt oxide (for example, Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 or Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 etc.), or lithium nickel cobalt aluminum oxide (e.g.
  • the lithium transition metal The complex oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 or Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 etc., and any one or a mixture of two or more of these may be used.
  • the positive electrode active material is a lithium transition metal complex oxide and may contain 60 mol% or more of nickel based on the total number of moles of transition metals contained in the lithium transition metal complex oxide.
  • the positive electrode active material is a lithium transition metal complex oxide, and the transition metal includes nickel; and at least one selected from manganese, cobalt, and aluminum, and may contain 60 mol% or more, specifically 60 mol% to 90 mol%, of nickel based on the total number of moles of the transition metal.
  • this lithium transition metal complex oxide using a high content of nickel is used together with the above-described non-aqueous electrolyte, it is preferable in that it can reduce by-products in the gas phase generated by structural collapse.
  • the positive electrode active material may include a lithium complex transition metal oxide represented by the following formula (A).
  • a, b, c and d may be 0.70 ⁇ a ⁇ 0.95, 0.025 ⁇ b ⁇ 0.20, 0.025 ⁇ c ⁇ 0.20, and 0 ⁇ d ⁇ 0.05, respectively.
  • a, b, c, and d may be 0.80 ⁇ a ⁇ 0.95, 0.025 ⁇ b ⁇ 0.15, 0.025 ⁇ c ⁇ 0.15, and 0 ⁇ d ⁇ 0.05, respectively.
  • a, b, c, and d may be 0.85 ⁇ a ⁇ 0.90, 0.05 ⁇ b ⁇ 0.10, 0.05 ⁇ c ⁇ 0.10, and 0 ⁇ d ⁇ 0.03, respectively.
  • the positive electrode active material may be included in the positive electrode active material layer at 80% to 99% by weight, preferably 92% to 98.5% by weight, in consideration of sufficient capacity of the positive electrode active material.
  • the positive electrode active material layer may further include a binder and/or a conductive material along with the positive electrode active material described above.
  • the binder is a component that helps bind active materials and conductive materials and bind to the current collector, and is specifically made of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, and hydroxypropyl cellulose. From the group consisting of wood, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber and fluoroelastomer. It may include at least one selected type, preferably polyvinylidene fluoride.
  • the binder may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in terms of ensuring sufficient binding force between components such as the positive electrode active material.
  • the conductive material can be used to assist and improve conductivity in secondary batteries, and is not particularly limited as long as it has conductivity without causing chemical changes.
  • the conductive material includes graphite such as natural graphite or artificial graphite; Carbon black such as acetylene black, Ketjen black, channel black, Paneth black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Conductive tubes such as carbon nanotubes; fluorocarbon; Metal powders such as aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and may preferably include carbon black in terms of improving conductivity.
  • the conductive material may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight.
  • the thickness of the positive electrode active material layer may be 30 ⁇ m to 400 ⁇ m, preferably 40 ⁇ m to 110 ⁇ m.
  • the positive electrode may be manufactured by coating a positive electrode slurry containing a positive electrode active material and optionally a binder, a conductive material, and a solvent for forming a positive electrode slurry on the positive electrode current collector, followed by drying and rolling.
  • the solvent for forming the positive electrode slurry may include an organic solvent such as NMP (N-methyl-2-pyrrolidone).
  • the solid content of the positive electrode slurry may be 40% by weight to 90% by weight, specifically 50% by weight to 80% by weight.
  • the separator includes typical porous polymer films conventionally used as separators, such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer.
  • Porous polymer films made from the same polyolefin-based polymer can be used alone or by laminating them, or conventional porous non-woven fabrics, such as non-woven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers, etc., can be used. It is not limited.
  • a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.
  • the non-aqueous electrolyte according to the present invention includes a lithium salt; organic solvent; and an additive; wherein the additive includes a first additive and a second additive, wherein the first additive includes a compound represented by the following formula (1), and the second additive includes lithium fluoromalonato (difluoro). lo)borate (LiFMDFB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorophosphate (LiDFP), and lithium difluorobis-(oxalate)phosphate (LiDFOP). It is characterized by containing at least one type.
  • R is independently halogen, nitrile group, propargyl group, ester group, ether group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted group.
  • n is an integer selected from 0 to 6.
  • the non-aqueous electrolyte of the present invention includes a first additive containing a coumarin-based compound having a specific structural formula as an additive, and lithium fluoromalonato(difluoro)borate (LiFMDFB) and lithium difluoro(oxalato)borate (LiDFOB). It is characterized in that it contains a second additive including etc.
  • a flexible, highly resilient, and durable SEI film can be formed on the cathode.
  • the lithium secondary battery according to the present invention has a large degree of volume expansion and forms the above-described SEI film on the silicon-based negative electrode, which is likely to cause electrolyte side reactions, thereby preventing cracking of the SEI film, preventing electrolyte side reactions, and increasing the thickness of the electrode film.
  • the overall performance of the lithium secondary battery especially high-temperature cycle life performance and high-temperature storage performance, can be improved.
  • the combined use of the first and second additives may actually cause an increase in resistance. Therefore, compared to the case where the first additive or the second additive is used alone, the improvement in effect may be minimal or may actually be reduced.
  • the lithium salt used in the present invention various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries can be used without limitation.
  • the lithium salt includes Li + as a cation, and F - , Cl - , Br - , I - , NO 3 - , N(CN) 2 - , BF 4 - , and ClO 4 - as anions.
  • the lithium salt is LiCl, LiBr, LiI, LiBF 4 , LiClO 4 , LiAlO 4, LiAlCl 4 , LiPF 6 , LiSbF 6 , LiAsF 6 , LiB 10 Cl 10 , LiBOB (LiB(C 2 O 4 ) 2 ) , LiCF 3 SO 3 , LiFSI (LiN(SO 2 F) 2 ), LiCH 3 SO 3 , LiCF 3 CO 2 , LiCH 3 CO 2 and LiBETI (LiN(SO 2 CF 2 CF 3 ) 2 ). It may include at least one type.
  • the lithium salt is LiBF 4 , LiClO 4 , LiPF 6 , LiBOB (LiB(C 2 O 4 ) 2 ), LiCF 3 SO 3 , LiTFSI (LiN(SO 2 CF 3 ) 2 ), LiFSI ((LiN(SO 2 F) 2 ) and LiBETI (LiN(SO 2 CF 2 CF 3 ) 2 ).
  • the lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5M to 5M, specifically 0.8M to 4M, and more specifically 0.8M to 2.0M.
  • concentration of the lithium salt satisfies the above range, the lithium ion yield (Li + transference number) and the degree of dissociation of lithium ions are improved, thereby improving the output characteristics of the battery.
  • the organic solvent is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as it can minimize decomposition due to oxidation reactions, etc. during the charging and discharging process of the secondary battery.
  • the organic solvent may include at least one selected from the group consisting of cyclic carbonate-based organic solvents, linear carbonate-based organic solvents, linear ester-based organic solvents, and cyclic ester-based organic solvents.
  • the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixture thereof.
  • the cyclic carbonate-based organic solvent is a high-viscosity organic solvent that has a high dielectric constant and can easily dissociate lithium salts in the electrolyte. Specifically, it is ethylene carbonate (EC), fluoroethylene carbonate (FEC), and propylene carbonate (PC). , 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate and vinylene carbonate, including at least one organic solvent selected from the group consisting of It may include at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and more specifically, it may include fluoroethylene carbonate (FEC).
  • EC ethylene carbonate
  • FEC fluoroethylene carbonate
  • PC propylene carbonate
  • the fluoroethylene carbonate (FEC) can form an SEI film with a high content of inorganic components such as LiF on the cathode, thereby increasing the durability of the SEI film. This improves lifespan performance and storage, especially when applied to a cathode containing a silicon-based active material. Improvement in characteristics can be expected.
  • the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, specifically dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, and ethylmethyl carbonate (EMC).
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethylmethyl carbonate
  • DEC diethyl carbonate
  • DEC diethyl carbonate
  • the diethyl carbonate is a symmetrical linear carbonate and there is no risk of transesterification, so it is preferable because it can prevent reduction stability due to production of by-products due to the transesterification reaction.
  • the diethyl carbonate is particularly preferable when applied to a negative electrode containing a silicon-based active material.
  • the organic solvent may be a mixture of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.
  • the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent are in a volume ratio of 5:95 to 40:60, specifically 7:93 to 30:70, and more specifically 8:92 to 30:70. Can be mixed.
  • the mixing ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent satisfies the above range, high dielectric constant and low viscosity characteristics can be simultaneously satisfied, and excellent ionic conductivity characteristics can be realized.
  • the organic solvent may be added to at least one carbonate-based organic solvent selected from the group consisting of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic organic solvent. It may further include at least one type of ester-based organic solvent selected from the group consisting of ester-based organic solvents.
  • the linear ester-based organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. there is.
  • the cyclic ester-based organic solvent may specifically include at least one selected from the group consisting of ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -caprolactone, ⁇ -valerolactone, and ⁇ -caprolactone. You can.
  • the organic solvent can be used by adding organic solvents commonly used in non-aqueous electrolytes without limitation, if necessary.
  • it may further include at least one organic solvent selected from the group consisting of an ether-based organic solvent, a glyme-based solvent, and a nitrile-based organic solvent.
  • the ether-based solvents include dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis (trifluoromethyl )-1,3-dioxolane (TFDOL) or a mixture of two or more of these may be used, but are not limited thereto.
  • the glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents, and is a solvent with low reactivity with metals, such as dimethoxyethane (glyme, DME), diethoxyethane, digylme, It may include, but is not limited to, at least one selected from the group consisting of triglyme and tetra-glyme (TEGDME).
  • DME dimethoxyethane
  • TEGDME tetra-glyme
  • the nitrile-based solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, and 4-fluorobenzonitrile. , difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.
  • the additive includes a first additive and a second additive.
  • the first additive includes a compound represented by the following formula (1).
  • R is independently halogen, nitrile group, propargyl group, ester group, ether group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted group.
  • n is an integer selected from 0 to 6.
  • the first additive includes a coumarin-based compound of the structural formula described above, and this coumarin-based compound has strong reducing properties at the negative electrode, and upon initial activation of the lithium secondary battery, the ring structure is opened to form a polyethylene oxide-based polymer-type SEI film. This is possible.
  • This polymer-type SEI film has the advantages of excellent flexibility and recovery.
  • the SEI film derived from the first additive has poor durability, it is necessary to use the second additive described later along with the first additive in order to achieve the improvement in high temperature cycle life performance and high temperature storage performance targeted by the present invention. do.
  • R is independently selected from a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a boron group, a borate group, an isocyanate group, It may include an isothiocyanate group, silyl group, siloxane group, sulfone group, sulfonate group, sulfate group, or a combination of two or more thereof.
  • R is independently of each other halogen (halogen may be selected from F, Cl, Br and I, and may specifically be F), nitrile group, propargyl group, ester group, ether group, Alternatively, it may include a combination of two or more thereof, and this substituent is preferable in that it has excellent reducing properties, is advantageous in forming a polymer-type SEI film, and also has excellent lithium ion transport performance.
  • halogen may be selected from F, Cl, Br and I, and may specifically be F
  • nitrile group nitrile group
  • propargyl group propargyl group
  • ester group ester group
  • ether group Alternatively, it may include a combination of two or more thereof, and this substituent is preferable in that it has excellent reducing properties, is advantageous in forming a polymer-type SEI film, and also has excellent lithium ion transport performance.
  • n may be an integer selected from 0 to 6, specifically, may be an integer selected from 1 to 6, and more specifically, n may be 1.
  • each R may be the same or different from each other.
  • the compound represented by Formula 1 may be at least one selected from the group consisting of a compound represented by Formula 2 below and a compound represented by Formula 3 below.
  • R is as defined in Formula 1.
  • the compounds represented by Formula 2 and Formula 3 are structures in which substituents exist at positions 3 and 7 of the ring structure (based on IUPAC nomenclature), respectively. In this case, it is advantageous to synthesize them at the above positions compared to other substitution positions. It is desirable in that respect. In particular, the compound represented by Formula 2 in which the substituent is present at position 3 is more preferable in that the uniformity of the reaction is improved when reduced to the cathode.
  • the compound represented by Formula 1 may include at least one member selected from the group consisting of compounds represented by Formulas 4 to 12 below.
  • the compound represented by Formula 1 may be more smoothly reduced to the cathode and is more advantageous for forming a polymer-type SEI film, and will specifically include at least one member selected from the group consisting of compounds represented by Formulas 4 to 7 below. It may include, more specifically, at least one member selected from the group consisting of the following Chemical Formula 4, the following Chemical Formula 5, and the following Chemical Formula 7, and more specifically, it has strong reducing properties along with the effects described above, and has an effect of suppressing transition metal elution. In terms of superiority, the compound represented by Formula 1 may include a compound represented by Formula 4 below.
  • the first additive will be included in the non-aqueous electrolyte in an amount of 0.01% to 10% by weight, specifically 0.05% to 7% by weight, more specifically 0.1% to 5% by weight, and more specifically 0.3% to 2% by weight. You can. When the content of the compound represented by Formula 1 satisfies the above range, it is desirable in terms of providing sufficient flexibility and recovery to the SEI film, while preventing an increase in resistance of the lithium secondary battery due to excessive addition and a corresponding decrease in life performance. do.
  • the second additive is lithium fluoromalonato(difluoro)borate (LiFMDFB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorophosphate (LiDFP), and lithium difluorobis- It includes at least one member selected from the group consisting of (oxalate) phosphate (LiDFOP).
  • the second additive may include a lithium salt additive containing fluorine, and the above-described lithium salt additive may form an inorganic-type SEI film such as LiF upon initial activation of a lithium secondary battery.
  • Inorganic-type SEI films such as LiF have excellent adhesion to the cathode surface, but it is difficult to completely cover the cathode surface, making it difficult to sufficiently prevent electrolyte side reactions.
  • the non-aqueous electrolyte is characterized by the combined use of a first additive and a second additive capable of forming a polymer-type/inorganic-type composite SEI film.
  • the polymer-type SEI film derived from the first additive covers the entire surface of the cathode to form an SEI film with excellent flexibility and recovery, and the inorganic-type SEI film derived from the second additive is formed as above. By being distributed in the polymer-type SEI film, the durability of the SEI film can be improved.
  • the non-aqueous electrolyte according to the present invention is flexible and has excellent recovery properties on the cathode surface, and can form an SEI film with improved durability and strength, resulting in electrolyte consumption due to electrolyte side reactions during battery operation and an increase in the thickness of the electrode film.
  • the performance of lithium secondary batteries can be improved, especially high-temperature cycle life performance and high-temperature storage performance.
  • the non-aqueous electrolyte according to the present invention when used with a negative electrode containing a silicon-based active material, it can form a flexible and durable SEI film on the silicon-based active material that has a large degree of volume expansion during charging and discharging, thereby increasing the volume expansion of the silicon-based active material.
  • This is desirable because it prevents damage to the SEI film, increases the thickness of the SEI film due to exposure of the surface of the new silicon-based active material due to volume expansion, and prevents electrolyte consumption.
  • the second additive may specifically include at least one selected from the group consisting of lithium fluoromalonato(difluoro)borate (LiFMDFB) and lithium difluoro(oxalato)borate (LiDFOB),
  • LiFMDFB lithium fluoromalonato(difluoro)borate
  • LiDFOB lithium difluoro(oxalato)borate
  • the second additive may include lithium fluoromalonato(difluoro)borate (LiFMDFB).
  • the second additive may include lithium difluoro(oxalato)borate (LiDFOB).
  • the second additive will be included in the non-aqueous electrolyte in an amount of 0.01% to 10% by weight, specifically 0.05% to 7% by weight, more specifically 0.1% to 5% by weight, and more specifically 0.3% to 2% by weight. You can. When the content of the compound represented by Formula 1 satisfies the above range, it is preferable in terms of providing sufficient durability and strength to the SEI film and preventing an increase in resistance of the lithium secondary battery due to excessive addition and a corresponding decrease in life performance. .
  • the weight ratio of the first additive and the second additive is 5:95 to 95:5, specifically 10:90 to 92:8, more specifically 16:84 to 91:9, even more specifically 30:70 to 70: 30, more specifically, 40:60 to 60:40, and the above-described weight ratio is preferred because the flexibility and durability of the SEI film can be simultaneously improved to a desirable level.
  • the additive may further include an additional additive or a third additive along with the first and second additives.
  • the additional additive may be included in the non-aqueous electrolyte to prevent decomposition of the non-aqueous electrolyte in a high-power environment, causing cathode collapse, or to improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and battery expansion inhibition at high temperatures.
  • the additional additives include vinylene carbonate, vinyl ethylene carbonate, propane sultone, propene sultone, succinonitrile, and adiponitrile. ), ethylene sulfate, LiBOB (Lithium bis-(oxalato)borate), TMSPa (Tris(trimethylsilyl) Phosphate), and TMSPi (Tris(trimethylsilyl) Phosphite). It may be vinylene carbonate.
  • the additional additive may be included in the non-aqueous electrolyte in an amount of 0.1% to 15% by weight.
  • the non-aqueous electrolyte may not contain a silyl group-containing additive.
  • the external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.
  • FEC fluoroethylene carbonate
  • DEC diethyl carbonate
  • a non-aqueous electrolyte was prepared by adding LiPF 6 as a lithium salt to the organic solvent, a compound represented by the following formula (4) as a first additive, LiFMDFB as a second additive, and vinylene carbonate (VC) as an additional additive.
  • the LiPF 6 was included in the non-aqueous electrolyte at a concentration of 1.5M.
  • the compound represented by Formula 4 was included at 0.5% by weight in the non-aqueous electrolyte, LiFMDFB was included at 0.5% by weight in the non-aqueous electrolyte, and vinylene carbonate used as the additional additive was included at 0.5% by weight in the non-aqueous electrolyte. was included.
  • Cathode active material LiNi 0.85 Co 0.05 Mn 0.07 Al 0.03 O 2 : conductive material (carbon nanotube): binder (polyvinylidene fluoride) in the solvent N-methyl-2-pyrrolidone at a weight ratio of 97.74:0.70:1.56. (NMP) was added to prepare a positive electrode mixture slurry (solid content: 75.5% by weight). The positive electrode mixture slurry was applied to one side of a positive electrode current collector (Al thin film) with a thickness of 15 ⁇ m, and dried and roll pressed to prepare a positive electrode.
  • a positive electrode current collector Al thin film
  • Negative active material Si: conductive material (carbon black): binder (styrene-butadiene rubber) was added to distilled water as a solvent at a weight ratio of 70.0:20.3:9.7 to prepare a negative electrode mixture slurry (solid content: 26% by weight).
  • the negative electrode mixture slurry was applied to one side of a negative electrode current collector (Cu thin film) with a thickness of 15 ⁇ m, and dried and roll pressed to prepare a negative electrode.
  • a polyethylene porous film separator was interposed between the prepared positive electrode and the negative electrode in a dry room, and then the prepared non-aqueous electrolyte was injected to prepare a secondary battery.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as Example 1, except that 0.1% by weight of the first additive was added to the non-aqueous electrolyte.
  • a non-aqueous electrolyte and lithium secondary battery were manufactured in the same manner as Example 1, except that 5.0% by weight of the first additive was added to the non-aqueous electrolyte.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 0.5% by weight of a compound represented by the following formula 5 instead of the compound represented by the formula 4 was included in the non-aqueous electrolyte as a first additive.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 0.5% by weight of a compound represented by the following formula 6 instead of the compound represented by the formula 4 was included in the non-aqueous electrolyte as a first additive.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 0.5% by weight of a compound represented by the following formula 7 instead of the compound represented by the formula 4 was included in the non-aqueous electrolyte as a first additive.
  • a non-aqueous electrolyte and lithium secondary battery were manufactured in the same manner as in Example 1, except that 0.5% by weight of LiDFP instead of LiFMDFB was included in the non-aqueous electrolyte as a second additive.
  • a non-aqueous electrolyte and lithium secondary battery were manufactured in the same manner as in Example 1, except that 0.5% by weight of LiDFOB instead of LiFMDFB was included in the non-aqueous electrolyte as a second additive.
  • a nonaqueous electrolyte and a lithium secondary battery were manufactured in the same manner as Example 1, except that 0.1% by weight of the second additive was included in the nonaqueous electrolyte.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 5% by weight of the second additive was included in the non-aqueous electrolyte.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as Example 8, except that 0.1% by weight of the second additive was included in the non-aqueous electrolyte.
  • a non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as Example 8, except that 5% by weight of the second additive was included in the non-aqueous electrolyte.
  • a non-aqueous electrolyte, lithium secondary battery was manufactured in the same manner as Example 1, except that the first and second additives were not added.
  • a non-aqueous electrolyte, lithium secondary battery was manufactured in the same manner as Example 1, except that the second additive was not added.
  • a non-aqueous electrolyte, lithium secondary battery was manufactured in the same manner as Example 1, except that the first additive was not added.
  • Example 1 1.5 FEC:DEC (volume ratio 10:90) Formula 4 0.5 LiFMDFB 0.5 VC 0.5
  • Example 2 1.5 FEC:DEC (volume ratio 10:90) Formula 4 0.1 LiFMDFB 0.5 VC 0.5
  • Example 3 1.5 FEC:DEC (volume ratio 10:90) Formula 4 5.0 LiFMDFB 0.5 VC 0.5
  • Example 5 1.5 FEC:DEC (volume ratio 10:90) Formula 6 0.5 LiFM
  • the lithium secondary batteries of Examples 1 to 12 and Comparative Examples 1 to 3 prepared above were charged to 4.2V under CC/CV, 0.33C conditions at 45°C using an electrochemical charger and discharger, and then charged under CC, 0.33C conditions. 300 cycles of charge and discharge were performed, with one cycle discharging to 3V, and the capacity retention rate was measured.
  • the capacity maintenance rate was calculated using the formula below, and the results are shown in Table 2 below.
  • Capacity maintenance rate (%) (discharge capacity after 300 cycles/discharge capacity after 1 cycle) ⁇ 100
  • the lithium secondary batteries of Examples 1 to 12 and Comparative Examples 1 to 3 prepared above were charged to 4.2V/55mA under 0.33C/4.2V constant current/constant voltage (CC/CV) conditions at room temperature and charged to 2.5 V at 0.33C.
  • Initial charging and discharging was performed by discharging, and then charged to 0.33C/4.2V constant current/constant voltage (CC/CV) 4.2V/55mA at room temperature and then stored at 60°C.
  • the secondary batteries were charged to 4.2V/55mA under 0.33C/4.2V constant current/constant voltage (CC/CV) conditions at room temperature and discharged to 2.5 V at 0.33C to measure the capacity during discharge.
  • Capacity maintenance rate was evaluated according to the formula below, and the results are shown in Table 2 below.
  • Capacity maintenance rate (%) (discharge capacity after N weeks of storage/initial discharge capacity) ⁇ 100
  • N is an integer greater than 1)
  • the lithium secondary batteries of Examples 1 to 12 using the non-aqueous electrolyte containing the first additive and the second additive according to the present invention have high temperature cycle life performance and high temperature compared to the lithium secondary batteries of Comparative Examples 1 to 3. It can be seen that high-temperature storage performance has been significantly improved.
  • Example 1 The same non-aqueous electrolyte used in Example 1 was used.
  • Cathode active material Li[Ni 0.85 Co 0.03 Mn 0.07 Al 0.03 ]O 2 ): conductive material (carbon nanotube): binder (polyvinylidene fluoride) mixed with solvent N-methyl-2- at a weight ratio of 97.74:0.70:1.56. Pyrrolidone (NMP) was added to prepare a positive electrode mixture slurry (solid content: 75.5% by weight). The positive electrode mixture slurry was applied to one side of a positive electrode current collector (Al thin film) with a thickness of 15 ⁇ m, and dried and roll pressed to prepare a positive electrode.
  • NMP Pyrrolidone
  • Negative active material Natural graphite: conductive material (carbon black): binder (styrene-butadiene rubber (SBR)-carboxymethylcellulose (CMC)) were added to distilled water as a solvent at a weight ratio of 95.0:1.5:3.5 to create a negative electrode mixture slurry ( Solid content 60% by weight) was prepared.
  • the negative electrode mixture slurry was applied to one side of a negative electrode current collector (Cu thin film) with a thickness of 15 ⁇ m, and dried and roll pressed to prepare a negative electrode.
  • a polyethylene porous film separator was interposed between the prepared positive electrode and the negative electrode in a dry room, and then the prepared non-aqueous electrolyte was injected to prepare a secondary battery.
  • a secondary battery was manufactured in the same manner as Reference Example 1, except that the non-aqueous electrolyte used in Comparative Example 2 was used as the non-aqueous electrolyte.
  • a secondary battery was manufactured in the same manner as Reference Example 1, except that the non-aqueous electrolyte used in Comparative Example 3 was used as the non-aqueous electrolyte.
  • the lithium secondary batteries of Reference Examples 1 to 3 prepared above were charged to 4.2V under CC/CV, 0.33C conditions at 45°C using an electrochemical charger and discharger, and then discharged to 3V under CC, 0.33C conditions. 300 cycles of charge and discharge were performed as 1 cycle, and the capacity retention rate was measured.
  • the capacity maintenance rate was calculated using the formula below, and the results are shown in Table 3 below.
  • Capacity maintenance rate (%) (discharge capacity after 300 cycles/discharge capacity after 1 cycle) ⁇ 100
  • the lithium secondary batteries of Reference Examples 1 to 3 prepared above were charged to 4.2V/55mA under 0.33C/4.2V constant current/constant voltage (CC/CV) conditions at room temperature and discharged to 2.5 V at 0.33C to perform initial charge and discharge. This was performed, and then charged to 0.33C/4.2V constant current/constant voltage (CC/CV) 4.2V/55mA at room temperature and then stored at 60°C. After storage, the secondary batteries were charged to 4.2V/55mA under 0.33C/4.2V constant current/constant voltage (CC/CV) conditions at room temperature and discharged to 2.5 V at 0.33C to measure the capacity during discharge.
  • CC/CV constant current/constant voltage
  • Capacity maintenance rate was evaluated according to the formula below, and the results are shown in Table 3 below.
  • Capacity maintenance rate (%) (discharge capacity after N weeks of storage/initial discharge capacity) ⁇ 100
  • N is an integer greater than 1)
  • Reference Experiment Example 1 Reference Experiment Example 2 High temperature cycle capacity maintenance rate (%, 300cycle) Capacity retention rate (%) when stored for 8 weeks
  • Reference example 1 78.7 87.5
  • Reference example 2 80.4 89.2
  • Reference example 3 82.1 90.9
  • lifespan performance and storage performance improvement effects of the present invention are expressed only when a negative electrode containing a silicon-based active material and the above-described non-aqueous electrolyte are combined.

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Abstract

La présente invention concerne une batterie secondaire au lithium comprenant : une électrode négative ; une électrode positive faisant face à l'électrode négative ; un séparateur disposé entre l'électrode négative et l'électrode positive ; et un électrolyte non aqueux. L'électrode négative comprend un matériau actif négatif, et le matériau actif négatif comprend un matériau actif à base de silicium. L'électrolyte non aqueux comprend un sel de lithium, un solvant organique et un additif, et l'additif comprend un premier additif et un second additif. Le premier additif comprend un composé à base de coumarine représenté par une formule chimique spécifique, et le second additif comprend au moins un élément choisi dans le groupe constitué par le fluoromalonato (difluoro) borate de lithium (LiFMDFB), le difluoro (oxalato) borate de lithium (LiDFOB), le difluorophosphate de lithium (LiDFP) et le difluorobis- (oxalate) phosphate de lithium (LiDFOP). Dans la batterie secondaire selon la présente invention, un film souple ayant une excellente durabilité est formé sur l'électrode négative comprenant un matériau actif à base de silicium, ce qui permet d'améliorer les caractéristiques de cycle à haute température et les caractéristiques de stockage à haute température.
PCT/KR2023/012295 2022-08-18 2023-08-18 Batterie secondaire au lithium WO2024039232A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20060037592A (ko) * 2004-10-28 2006-05-03 삼성에스디아이 주식회사 리튬 전지용 전해질 및 이를 포함하는 리튬 전지
CN102569889A (zh) * 2012-02-06 2012-07-11 深圳新宙邦科技股份有限公司 锂离子电池非水电解液与锂离子电池
KR20200072723A (ko) * 2018-12-13 2020-06-23 현대자동차주식회사 리튬 이차전지
KR20210060330A (ko) * 2019-11-18 2021-05-26 주식회사 엘지화학 리튬 이차전지용 비수전해액 및 이를 포함하는 리튬 이차전지
WO2022097073A1 (fr) * 2020-11-07 2022-05-12 Eocell Limited Électrolyte non aqueux pour batterie secondaire au lithium-ion, et batterie secondaire au lithium-ion contenant celui-ci

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20060037592A (ko) * 2004-10-28 2006-05-03 삼성에스디아이 주식회사 리튬 전지용 전해질 및 이를 포함하는 리튬 전지
CN102569889A (zh) * 2012-02-06 2012-07-11 深圳新宙邦科技股份有限公司 锂离子电池非水电解液与锂离子电池
KR20200072723A (ko) * 2018-12-13 2020-06-23 현대자동차주식회사 리튬 이차전지
KR20210060330A (ko) * 2019-11-18 2021-05-26 주식회사 엘지화학 리튬 이차전지용 비수전해액 및 이를 포함하는 리튬 이차전지
WO2022097073A1 (fr) * 2020-11-07 2022-05-12 Eocell Limited Électrolyte non aqueux pour batterie secondaire au lithium-ion, et batterie secondaire au lithium-ion contenant celui-ci

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