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US-12620621-B2 - Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery comprising same

US12620621B2US 12620621 B2US12620621 B2US 12620621B2US-12620621-B2

Abstract

The present disclosure relates to a non-aqueous electrolyte for a lithium secondary battery, including a lithium salt, an organic solvent and a compound represented by Chemical Formula 1; and a lithium secondary battery including the same, wherein R1, R2, L and m are described herein.

Inventors

  • Kyung Mi LEE
  • Jung Min Lee
  • Chul Eun Yeom
  • Jung Gu HAN
  • Chul Haeng Lee

Assignees

  • LG ENERGY SOLUTION, LTD.

Dates

Publication Date
20260505
Application Date
20220922
Priority Date
20211005

Claims (12)

  1. 1 . A non-aqueous electrolyte for a lithium secondary battery, comprising: a lithium salt; an organic solvent; and a compound represented by Chemical Formula 1: in Chemical Formula 1, R1 is each independently an alkyl group having 1 to 10 carbon atoms, R2 is an alkylene group having 1 to 10 carbon atoms, L is a direct bond, —O—, —COO—, —RO—, or —R′COO—, R and R′ are each independently an alkylene group having 1 to 10 carbon atoms, and m is an integer from 0 to 5, wherein the lithium salt comprises one or more of LiPF 6 , LiCIO 4 , LiBF 4 , LIN (FSQ 2 ) 2 , LIN (SO 2 CF 3 ) 2, lithium bis (pentafluoroethanesulfonyl) imide, LiSO 3 CF 3 , LiPO 2 F 2 , lithium bis (oxalate) borate, lithium difluoro (oxalate) borate, lithium difluoro (bisoxalato) phosphate, lithium tetrafluoro (oxalate) phosphate, or lithium fluoromalonato (difluoro) borate.
  2. 2 . The non-aqueous electrolyte of claim 1 , wherein the compound represented by Chemical Formula 1 comprises one or more of a compound represented by Chemical Formula 1-1 or Chemical Formula 2-1: in Chemical Formula 1-1 and Chemical Formula 2-1, R1, R2, L and m are the same as those defined in Chemical Formula 1.
  3. 3 . The non-aqueous electrolyte of claim 1 , wherein L of Chemical Formula 1 is —O— or —COO—.
  4. 4 . The non-aqueous electrolyte of claim 1 , wherein the compound represented by Chemical Formula 1 comprises one or more of a compound represented by Chemical Formula 1-2, Chemical Formula 1-3, Chemical Formula 2-2 or Chemical Formula 2-3: in Chemical Formula 1-2, Chemical Formula 1-3, Chemical Formula 2-1 and Chemical Formula 2-3, wherein R1, R2 and m are the same as those defined in Chemical Formula 1.
  5. 5 . The non-aqueous electrolyte of claim 1 , the compound represented by Chemical Formula 1 comprises one or more of a compound represented by Chemical Formula 1A, Chemical Formula 1B, Chemical Formula 2A or Chemical Formula 2B:
  6. 6 . The non-aqueous electrolyte of claim 1 , wherein a content of the compound represented by Chemical Formula 1 is 0.1 wt % to 5 wt % based on a total weight of the non-aqueous electrolyte.
  7. 7 . The non-aqueous electrolyte of claim 1 , wherein a content of the compound represented by Chemical Formula 1 is 0.1 wt % to 1 wt % based on a total weight of the non-aqueous electrolyte.
  8. 8 . The non-aqueous electrolyte of claim 1 , further comprising one or more additives selected from vinylene carbonate, vinyl ethylene carbonate, 1,3-propane sultone, ethylene sulfate, lithium difluoro oxalato borate, or lithium difluorophosphate.
  9. 9 . The non-aqueous electrolyte of claim 1 , wherein the organic solvent comprises a mixture of a cyclic carbonate-based solvent and a linear carbonate-based solvent.
  10. 10 . A lithium secondary battery comprising: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; a separator interposed between the positive electrode and the negative electrode; and the non-aqueous electrolyte of claim 1 .
  11. 11 . The lithium secondary battery of claim 10 , wherein the positive electrode active material comprises a lithium composite transition metal oxide represented by Chemical Formula 3: Li 1+x (Ni a Co b Mn c M d )O 2 [Chemical Formula 3] in Chemical Formula 3, M is one or more selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B or Mo, 1+x, a, b, c and d each are an atomic fraction of Li, Ni, Co, Mn and M, respectively, and 0≤x≤0.2, 0.50≤a<1, 0<b≤0.25, 0<c≤0.25, 0≤d≤0.1, and a+b+c+d=1.
  12. 12 . The lithium secondary battery of claim 11 , wherein in Chemical Formula 3, 0.80≤a≤0.95, 0.025≤b≤0.15, 0.025≤c≤0.15, and 0≤d≤0.05.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority from Korean Patent Application No. 10-2021-0131937, filed on Oct. 5, 2021, and Korean Patent Application No. 10-2022-0115214, filed on Sep. 13, 2022, the disclosures of which are incorporated herein by reference. BACKGROUND OF THE INVENTION The present disclosure relates to a non-aqueous electrolyte for a lithium secondary battery and a lithium secondary battery including the same. Lithium secondary batteries are generally manufactured by a method of forming an electrolyte assembly by interposing a separator between a positive electrode including a positive electrode active material comprising a transition metal oxide containing lithium and a negative electrode including a negative electrode active material capable of storing lithium ions, inserting the electrode assembly into a battery case, then injecting a non-aqueous electrolyte serving as a medium for transferring lithium ions, and then sealing the assembly. Lithium secondary batteries can be miniaturized and have high energy density and a high operating voltage, and thus are applied to various fields such as mobile devices, electronic products, and electric vehicles. As the application fields of lithium secondary batteries have diversified, the required physical property conditions are also gradually increasing, and in particular, there is a need for developing a lithium secondary battery that can be stably driven under high voltage and high temperature conditions and has long life characteristics. Meanwhile, when a lithium secondary battery is driven under high voltage and/or high temperature conditions, PF6− anions may be thermally decomposed from lithium salts such as LiPF6 contained in an electrolyte to generate a Lewis acid such as PF5, which reacts with moisture to produce HF. Such decomposition products such as PF5 and HF can not only destroy a film formed on the surface of an electrode, but also cause a decomposition reaction of an organic solvent. Further, the electrolyte decomposition product may react with the decomposition products of a positive electrode active material to elute transition metal ions, and the eluted transition metal ions may be electrodeposited on a negative electrode to destroy a film formed on the surface of the negative electrode. When an electrolyte decomposition reaction continues on the film thus destroyed, the performance of the battery further deteriorates, so there is a need for developing a secondary battery capable of maintaining excellent performance even under high voltage and high temperature conditions. RELATED ART DOCUMENT Patent Document KR 10-2003-0061219 A BRIEF SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the aforementioned problems, and is intended to provide a non-aqueous electrolyte capable of suppressing the decomposition reaction of an electrolyte and forming a reinforced film on the electrode by including a compound having a structure in which a propargyl group is bonded to coumarin, and a lithium secondary battery including the same. According to an exemplary embodiment, the present disclosure provides a non-aqueous electrolyte for a lithium secondary battery, including: a lithium salt; an organic solvent; and a compound represented by the following Chemical Formula 1. In Chemical Formula 1, R1 is each independently an alkyl group having 1 to 10 carbon atoms, R2 is an alkylene group having 1 to 10 carbon atoms, L is a direct bond, —O—, —COO—, —RO—, or —R′COO—, R and R′ are each independently an alkylene group having 1 to 10 carbon atoms, and m is an integer from 0 to 5. According to another exemplary embodiment, the present disclosure provides a lithium secondary battery including: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; a separator interposed between the positive electrode and the negative electrode; and the non-aqueous electrolyte for a lithium secondary battery. DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in more detail. In general, anions included in lithium salts such as LiPF6, which are widely used in an electrolyte for a lithium secondary battery, form decomposition products such as hydrogen fluoride (HF) and PF5 by thermal decomposition, moisture, or the like. Such decomposition products have the properties of an acid and deteriorate a film or the surface of an electrode in a battery. Transition metals in a positive electrode are easily eluted into an electrolyte due to the decomposition product of the electrolyte, the structural change of the positive electrode due to repeated charging and discharging, and the like, and the eluted transition metal is re-deposited to increase the resistance of the positive electrode. In addition, when the eluted transition metal moves to a negative electrode through the electrolyte, the eluted transition