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KR-20260066562-A - LITHIUM SECONDARY BATTERY

KR20260066562AKR 20260066562 AKR20260066562 AKR 20260066562AKR-20260066562-A

Abstract

The present invention provides a lithium secondary battery comprising: a cathode; an anode facing the cathode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte; wherein the cathode comprises a carbon-based active material, the non-aqueous electrolyte comprises a lithium salt, an organic solvent, and an additive, wherein the additive comprises a first additive, a second additive, and a third additive, wherein the first additive comprises a compound represented by Formula 1, the second additive comprises a cyclic carbonate-based compound substituted with two or more fluorines, and the third additive comprises lithium nitrate ( LiNO₃ ). The secondary battery according to the present invention can improve high-temperature cycle characteristics and high-temperature storage characteristics by forming a flexible and highly durable film on the cathode containing the carbon-based active material.

Inventors

  • 허은선
  • 이철행
  • 조윤교
  • 노주란

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260512
Application Date
20241104

Claims (12)

  1. A cathode; an anode facing the cathode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte; comprising, The above cathode includes a cathode active material, and The above-mentioned negative electrode active material includes a carbon-based active material, and The above-mentioned non-aqueous electrolyte comprises a lithium salt, an organic solvent, and an additive, and The above additive includes a first additive, a second additive, and a third additive, and The above first additive comprises a compound represented by the following chemical formula 1, and The second additive above comprises a cyclic carbonate-based compound substituted with two or more fluorines, and The above third additive is a lithium secondary battery comprising lithium nitrate ( LiNO₃ ): [Chemical Formula 1] In the above chemical formula 1, R independently comprises a proparzyl 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, or a combination of two or more of these, and n is an integer selected from 1 to 6.
  2. In paragraph 1, In the above chemical formula 1, R is a lithium secondary battery comprising a proparzyl group as a terminal group.
  3. In paragraph 1, A lithium secondary battery comprising at least one compound selected from the group consisting of compounds represented by the following chemical formulas 1A to 1C, represented by the compound represented by the above chemical formula 1: [Chemical Formula 1A] [Chemical Formula 1B] [Chemical Formula 1C] In the above chemical formulas 1A to 1C, R is as defined in the above chemical formula 1.
  4. In paragraph 1, A lithium secondary battery comprising at least one compound selected from the group consisting of compounds represented by the following chemical formulas 1A-1 to 1C-1, represented by the compound represented by the above chemical formula 1: [Chemical Formula 1A-1] [Chemical Formula 1B-1] [Chemical Formula 1C-1] .
  5. In paragraph 1, A lithium secondary battery in which the first additive is included in an amount of 0.01% to 10.0% by weight based on the total weight of the non-aqueous electrolyte.
  6. In paragraph 1, A lithium secondary battery comprising at least one selected from the group consisting of the second additive, fluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate, tetrafluoroethylene carbonate, and 3,3,3-trifluoropropylene carbonate.
  7. In paragraph 1, A lithium secondary battery in which the second additive is difluoroethylene carbonate.
  8. In paragraph 1, A lithium secondary battery in which the above-mentioned second additive is included in an amount of 0.01% to 10.0% by weight based on the total weight of the non-aqueous electrolyte.
  9. In paragraph 1, A lithium secondary battery in which the above-mentioned third additive is included in an amount of 0.01% to 10.0% by weight based on the total weight of the non-aqueous electrolyte.
  10. In paragraph 1, A lithium secondary battery comprising at least one fourth additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, propane sulfone, propene sulfone, succinonitrile, adiponitrile, ethylene sulfate, LiBOB (Lithium bis-(oxalato)borate), TMSPa (Tris(trimethylsilyl) Phosphate), and TMSPi (Tris(trimethylsilyl) Phosphite).
  11. In paragraph 1, A lithium secondary battery in which the carbon-based active material is at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon.
  12. In paragraph 1, A lithium secondary battery in which the above-mentioned negative electrode further comprises a silicon-based active material.

Description

Lithium Secondary Battery The present invention relates to a lithium secondary battery with improved high-temperature cycle life performance and high-temperature storage performance. Recently, as the application areas of lithium-ion batteries have rapidly expanded to include not only power supply for electronic devices such as electrical, electronic, telecommunications, and computers, but also power storage for large-area devices such as automobiles and power storage systems, there is a growing demand for high-capacity, high-output, and high-stability secondary batteries. The above lithium secondary battery is largely composed of a positive electrode made 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. At this time, the negative electrode may include a negative electrode active material such as a carbon-based active material. In the case of the above-mentioned lithium secondary battery, a film (SEI film) is formed on the positive and/or negative electrode during the initial activation process. This protects the positive and negative electrodes during battery operation and prevents electrolyte consumption caused by side reactions. If a robust electrode film is not formed on the positive and/or negative electrode during this initial activation process, it may lead to problems such as capacity degradation and reduced lifespan. In particular, carbon-based active materials among cathode active materials are attracting attention for exhibiting higher capacity compared to carbon-based materials, but they have the disadvantage of significant volume changes due to lithium insertion and extraction. This volume expansion of carbon-based active materials causes numerous problems, such as reducing the durability of the already formed SEI film, continuous electrolyte consumption due to the formation of new cathode active material surfaces, and an increase in SEI film thickness, which leads to capacity degradation and reduced lifespan. Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. Meanwhile, prior to describing the present invention, unless otherwise specifically stated in the present invention, "*" refers to a connected portion (bonding site) between identical or different atoms or terminal portions of a chemical formula. In addition, in the description of "a to b carbon atoms" within this specification, "a" and "b" refer to the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to " b " carbon atoms. For example, "alkyl group having 1 to 5 carbon atoms" refers to an alkyl group containing 1 to 5 carbon atoms, namely CH3- , CH3CH2- , CH3CH2CH2- , ( CH3 ) 2CH- , CH3CH2CH2CH2- , ( CH3 ) 2CHCH2- , CH3CH2CH2CH2- , ( CH3 ) 2CHCH2CH2- , etc. In addition, in this specification, alkyl groups or aryl groups may all be substituted or unsubstituted. Unless otherwise defined, the term "substitution" above means that at least one hydrogen bonded to a carbon is substituted with an element other than hydrogen, for example, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, a cycloalkynyl group having 3 to 12 carbon atoms, a heterocycloalkyl group having 3 to 12 carbon atoms, a heterocycloalkenyl group having 3 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, a halogen atom, a fluoroalkyl group having 1 to 20 carbon atoms, a nitro group, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 2 to 20 carbon atoms, or a halogen atom having 6 to 20 carbon atoms. It means that it is substituted with a haloaryl group, etc., and preferably means an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or a halogen atom. The present invention will be described in more detail below. A lithium secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination of technically feasible configurations among the configuratio