Electrolyte solution and secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-2024030490-A1
Application number	US-202318208389-A
Country	US
Kind code	A1
Filing date	Jun 12, 2023
Priority date	Jun 14, 2022
Publication date	Jan 25, 2024
Grant date	—

Abstract

The present invention relates to an electrolyte solution and a secondary battery including the same. According to the present invention, the present invention has an effect of providing a secondary battery having improved charging efficiency and output due to low discharge resistance and having a long lifespan and excellent high-temperature capacity retention rate by suppressing increase in thickness.

First claim

1 . An electrolyte solution, comprising an organic solvent, a lithium salt, a phosphorus-based cesium salt, and an additive,
wherein, based on 100% by weight of the electrolyte solution, the additive comprises two or more selected from compounds represented by Chemical Formulas 1 and 2 below in an amount of 0.01 to 20% by weight:

wherein, in Chemical Formulas 1 and 2, A is independently selected from C═O, O=P=O, O=S=O, O=N=O, P—F, P—Cl, P—Br, and P—I; X 1 , X 2 , X 3 , X 1 ′, X 2 ′, and X 3 ′ are independently a bond or oxygen; n is an integer from 0 to 3; R 1 and R 1 ′ are independently a single bond, a double bond, or a substituted or unsubstituted alkylene having 1 to 10 carbon atoms and comprise one or more carbon atoms; and R 2 , R 3 , R 2 ′, and R 3 ′ are independently a substituted or unsubstituted alkylene having 1 to 10 carbon atoms and comprise one or more carbon atoms.

2 . The electrolyte solution according to claim 1 , wherein the additive comprises a compound in which A is selected from O=P=O, O=S=O, and O=N=O and a compound in which A is C═O, or comprises a compound in which A is selected from P—F, P—Cl, P—Br, and P—I and a compound in which A is C═O.

3 . The electrolyte solution according to claim 2 , wherein the compound in which A is selected from O=P=O, O=S=O, and O=N=O comprises one or more selected from compounds represented by Chemical Formulas 3 to 6 below:

wherein, in Chemical Formulas 3 to 6, a solid line is a bond; carbon is located at a point where no separate element is shown and bonds meet; and the number of hydrogens satisfying a valence of the carbon is omitted.

4 . The electrolyte solution according to claim 2 , wherein the compound in which A is C═O is selected from compounds represented by Chemical Formulas 7 to 9 below:

wherein, in Chemical Formulas 7 to 9, a solid line is a bond; carbon is located at a point where no separate element is shown and bonds meet; and the number of hydrogens satisfying a valence of the carbon is omitted.

5 . The electrolyte solution according to claim 2 , wherein the compound in which A is selected from P—F, P—Cl, P—Br, and P—I is selected from compounds represented by Chemical Formulas 10 and 11 below:

wherein, in Chemical Formulas 10 and 11, a solid line is a bond; carbon is located at a point where no separate element is shown and bonds meet; and the number of hydrogens satisfying a valence of the carbon is omitted.

6 . The electrolyte solution according to claim 2 , wherein the compound in which A is selected from O=P=O, and O=N=O and the compound in which A is C═O are comprised in a weight ratio of 1:0.5 to 6.0.

7 . The electrolyte solution according to claim 2 , wherein the compound in which A is selected from P—F, P—Cl, P—Br, and P—I and the compound in which A is C═O are comprised in a weight ratio of 1:0.5 to 6.0.

8 . The electrolyte solution according to claim 1 , wherein the phosphorus-based cesium salt comprises a phosphate compound substituted with 1 to 6 halogen atoms.

9 . The electrolyte solution according to claim 6 , wherein the compound in which A is selected from O=P=O, O=S=O, and O=N=O, the compound in which A is C═O, and the phosphorus-based cesium salt are comprised in a weight ratio of 1:0.5 to 6.0:0.1 to 3.

10 . The electrolyte solution according to claim 7 , wherein the compound in which A is selected from P—F, P—Cl, P—Br, and P—I, the compound in which A is C═O, and the phosphorus-based cesium salt are comprised in a weight ratio of 1:0.5 to 6.0:0.1 to 3.

11 . The electrolyte solution according to claim 1 , wherein the lithium salt comprises one or more selected from the group consisting of LiPF 6 , LiClO 4 , LiTFSI, LiAsF 6 , LiBF 4 , LiBF 6 , LiSbF 6 , LiAlO 4 , LiAlCl 4 , LiBOB, LiB 10 Cl 10 , LiAlCl 4 , LiAlO 4 , LiClO 4 , LiCF 3 SO 3 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiCH 3 SO 3 , LiBeTI, LiC 4 F 9 SO 3 , LiN(C 2 F 5 SO 3 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , LiN(CaF 2a+1 SO 2 )(CbF 2b+1 S 02 ) (a and b are natural numbers), LiCl, LiI, LiBr, and LiB(C 2 O 4 ) 2 .

12 . The electrolyte solution according to claim 1 , wherein the organic solvent comprises two or more selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl ethyl carbonate (MEC), fluoroethylene carbonate (FEC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-butylene carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

13 . The electrolyte solution according to claim 1 , wherein, based on 100% by weight in total of the electrolyte solution, the electrolyte solution comprises one or more additives selected from the group consisting of boron compounds, phosphorus compounds, sulfur compounds, and nitrogenous compounds in an amount of 10% by weight or less.

14 . An electrolyte solution additive, comprising:
a phosphorus-based cesium salt; and two or more selected from compounds represented by Chemical Formulas 1 and 2 below:

wherein, in Chemical Formulas 1 and 2, A is independently selected from C═O, O=P=O, O=S=O, O=N=O, P—F, P—Cl, P—Br, and P—I; X 1 , X 2 , X 3 , X 1 ′, X 2 ′, and X 3 ′ are independently a bond or oxygen; n is an integer from 0 to 3; R 1 and R 1 ′ are independently a single bond, a double bond, or a substituted or unsubstituted alkylene having 1 to 10 carbon atoms and comprise one or more carbon atoms; and R 2 , R 3 , R 2 ′, and R 3 ′ are independently a substituted or unsubstituted alkylene having 1 to 10 carbon atoms and comprise one or more carbon atoms.

15 . A lithium secondary battery, comprising an anode, a cathode, a separator disposed between the anode and the cathode, and an electrolyte solution,
wherein the electrolyte solution is the electrolyte solution according to claim 1 .

16 . The lithium secondary battery according to claim 15 , wherein the lithium secondary battery has a discharge resistance value of 32.5 mΩ or less at 60° C.

17 . The lithium secondary battery according to claim 15 , wherein the lithium secondary battery has a recovery capacity of 770 mAh or more at 60° C.

18 . The lithium secondary battery according to claim 15 , wherein the lithium secondary battery has a thickness increase rate of 10.5% or less as measured at 60° C. and calculated by Equation 1 below:
Thickness increase rate (%)={(Thickness after storage at high temperature−Initial thickness)/Initial thickness}×100  [Equation 1]

Assignees

• Soulbrain Co Ltd

Inventors

• Yun Jong Cheol
• Kim Min Goo
• Lee Sang Ho
• Han Ji Seong
• Jang Min Jung

Classifications

• H01M10/0567 Primary

  characterised by the additives · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M10/0569

  characterised by the solvents · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M2300/0042

  Four or more solvents · CPC title