Search

EP-4435917-B1 - ELECTROLYTE FOR RECHARGEABLE LITHIUM BATTERY AND RECHARGEABLE LITHIUM BATTERY INCLUDING THE SAME

EP4435917B1EP 4435917 B1EP4435917 B1EP 4435917B1EP-4435917-B1

Inventors

  • BAE, Tae Hyon
  • LEE, HARIM
  • KIM, Sanghyung
  • SON, Seunghyeon
  • YU, ARUM
  • KIM, YUNHEE

Dates

Publication Date
20260506
Application Date
20240207

Claims (15)

  1. An electrolyte for a rechargeable lithium battery (100), the electrolyte comprising a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive comprises: a first compound selected from among a compound represented by Chemical Formula 1, CsPF 6 , and a combination thereof; and Ag salt, wherein, in Chemical Formula 1, R 1 and R 2 are each independently a fluoro group or a substituted C1 to C10 fluoroalkyl group containing at least one fluorine (F).
  2. The electrolyte as claimed in claim 1, wherein the first compound comprises the compound represented by Chemical Formula 1, and wherein R 1 and R 2 in Chemical Formula 1 are each independently a fluoro group or a C1 to C4 fluoroalkyl group substituted with at least three fluoro groups.
  3. The electrolyte as claimed in claim 1 or 2, wherein the first compound comprises the compound represented by Chemical Formula 1, and wherein Chemical Formula 1 is represented by any one of Chemical Formula 1-1 or Chemical Formula 1-2:
  4. The electrolyte as claimed in any of claims 1 to 3, wherein the first compound is present in an amount of 0.1 wt% to 5.0 wt% based on a total weight of the electrolyte for a rechargeable lithium battery.
  5. The electrolyte as claimed in any of claims 1 to 4, wherein the Ag salt comprises at least one selected from AgNO 3 , AgPF 6 , AgFSI, AgTFSI, AgF, AgSO 3 CF 3 , AgBF 4 , AgNO 2 , AgN 3 , and AgCN.
  6. The electrolyte as claimed in any of claims 1 to 5, wherein the Ag salt is present in an amount of 0.1 wt% to 10.0 wt% based on a total weight of the electrolyte for a rechargeable lithium battery.
  7. The electrolyte as claimed in any of claims 1 to 6, wherein the first compound and the Ag salt are present in a weight ratio of 1:9 to 6:4.
  8. The electrolyte as claimed in any of claims 1 to 7, wherein the additive further comprises a fluorinated ketone.
  9. The electrolyte as claimed in claim 8, wherein the fluorinated ketone is represented by Chemical Formula 2: and wherein, in Chemical Formula 2, M is a substituted or unsubstituted C1 to C30 alkylene group, a substituted or unsubstituted C2 to C30 alkenylene group, or a substituted or unsubstituted C2 to C30 alkynylene group, n is one of the integers from 0 to 5, and R 3 and R 4 are each independently, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C2 to C30 alkenyl group, a substituted or unsubstituted C2 to C30 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group, at least one of R 3 or R 4 comprising one or more fluorines (F).
  10. The electrolyte as claimed in claim 8 or 9, wherein the fluorinated ketone is represented by Chemical Formula 2-1: and wherein, in Chemical Formula 2-1, R 5 and R 6 are each independently a substituted or unsubstituted C1 to C30 alkyl group, and at least one of R 5 or R 6 comprises one or more fluorine (F).
  11. The electrolyte as claimed in any of claims 8 to 10, wherein the fluorinated ketone is represented by one selected from among Chemical Formula 2-2 and Chemical Formula 2-3:
  12. The electrolyte as claimed in any of claims 8 to 11, wherein the fluorinated ketone is present in an amount of about 1.0 wt% to about 10.0 wt% based on a total weight of the electrolyte for the rechargeable lithium battery.
  13. The electrolyte as claimed in any of claims 1 to 12, wherein the additive is present in an amount of about 1.0 wt% to about 30.0 wt% based on a total weight of the electrolyte for the rechargeable lithium battery.
  14. A rechargeable lithium battery (100), comprising a positive electrode (114) comprising a positive electrode active material; a negative electrode (112) comprising a negative electrode active material; a separator (113) between the positive electrode (114) and the negative electrode (112); and the electrolyte as claimed in claim 1.
  15. The rechargeable lithium battery (100) as claimed in claim 14, wherein the negative electrode (112) has a negative electrode active material density of greater than or equal to 1.6 gram per cubic centimeter (g/cc).

Description

BACKGROUND 1. Field One or more aspects of embodiments of the present disclosure relate to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte. 2. Description of the Related Art A rechargeable lithium battery may be recharged and has three or more times as high energy density per unit weight as a comparable lead storage battery, nickel-cadmium battery, nickel hydrogen battery, nickel zinc battery and/or the like. It may be also charged at a relatively high rate and thus, is commercially manufactured for a laptop, a cell phone, an electric tool, an electric bike, and/or the like, and research on improvement of additional energy density have been actively made. Such a rechargeable lithium battery is manufactured by injecting an electrolyte into a battery cell, which includes a positive electrode including a positive electrode active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative electrode active material capable of intercalating/deintercalating lithium ions. An organic solvent in which a lithium salt is dissolved is utilized as an electrolyte, and the electrolyte is important in determining stability and performance of a rechargeable lithium battery. Implementation of a high-capacity and high-energy density battery requires (or there is a desire for) the design of a battery drivable at a relatively high voltage of 4.5 V or greater, that should result in increased energy-density and/or electrode active material density of the electrode, and improved high-speed charging performance. However, under severe conditions such as in the high voltage and the high-speed charging, deterioration of the positive electrode and growth of lithium dendrites on the surface of the negative electrode accelerate undesired reaction(s) (e.g., undesired side reaction(s)) between the electrodes and the electrolyte. The undesired reaction(s) may reduce the cycle-life of the battery and initiate gas generation and/or the like that may compromise the range of conditions for safe operation of the battery (e.g., battery safety may be comprised or aggravated due to gas generation, and/or the like). Methods of protecting the electrodes through surface treatment to reduce or suppress the undesired reaction(s) with the electrolyte have been investigated. However, studies of surface treatment of the positive electrode have not suitably achieved and/or have failed to achieve sufficient protection effects under high voltage-driving conditions, and the surface treatment of the negative electrode has been reported to cause an additional problem of deteriorating battery capacity. Accordingly, in the design of high-capacity electrodes capable of operating at relatively a relatively high voltage with relatively high-speed charging, development of an electrolyte capable of improving battery safety and performance is desired, needed, and/or required. Current techniques for applying a low viscosity ester-based solvent to the electrolyte to suppress or reduce lithium dendrites of the negative electrode and thus improve electrolyte impregnability have been investigated. However, the ester-based solvent has relatively low oxidation resistance and relatively high flammability which may disadvantageously deteriorate battery performance and safety at high voltage. SUMMARY The present invention is set out in the appended set of claims, wherein the drawings and respective description relate to advantageous embodiments thereof. It was an object of the present invention to provide an electrolyte capable of reducing or suppressing generation of lithium dendrites in the negative electrode by improving the impregnation of the negative electrode (e.g., by improving conduction of lithium ions of the negative electrode) and uniformizing the intercalation of lithium ions on the surface of the negative electrode. It was also an object of the present invention to provide a rechargeable lithium battery with an improved charging performance, high-temperature cycle-life characteristics, and safety. In some embodiments, an electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a first compound selected from among a compound represented by Chemical Formula 1, CsPF6, and a combination thereof; and an Ag salt. In Chemical Formula 1, R1 and R2 may each independently be a fluoro group or a substituted C1 to C10 fluoroalkyl group containing at least one fluorine (F). R1 and R2 in Chemical Formula 1 may each independently be a fluoro group or a C1 to C4 fluoroalkyl group substituted with at least three fluoro groups. Chemical Formula 1 may be represented by any one selected from among Chemical Formula 1-1 and Chemical Formula 1-2. The first compound may be included (e.g., be present) in an amount of 0.1 wt% to 5.0 wt% based on a total weight of the electrolyte for a recha