KR-102964331-B1 - Low-temperature lithium-ion battery electrolyte, method for manufacturing the same, and lithium-ion battery

Abstract

The present invention relates to the field of lithium-ion battery technology, and more particularly to a low-temperature lithium-ion battery electrolyte, a method for manufacturing the same, and a lithium-ion battery. The low-temperature lithium-ion battery electrolyte of the present invention comprises an electrolyte salt and an organic solvent; wherein the organic solvent comprises a fluorocarboxylate ester, a fluorocarbonate ester, and 1,3-dioxolane. Fluorocarboxylate esters have a low freezing point and are suitable as low-temperature electrolyte solvents, and fluorocarbonate esters are mixed with fluorocarboxylate esters as eutectic agents to control the low-temperature performance and film formation characteristics of the electrolyte, and the introduction of 1,3-dioxolane, which has a low freezing point and low viscosity, significantly reduces the impedance of the battery. The low-temperature lithium-ion battery electrolyte of the present invention can effectively improve the conductivity of lithium ions at low temperatures, which is advantageous for the capacity of the lithium-ion battery at low temperatures, and in particular, can improve the discharge specific capacity and capacity retention rate of a lithium iron phosphate lithium-ion battery under low-temperature conditions.

Inventors

• 팡 춘
• 리우 시치
• 청 팡위안
• 조우 위치안

Assignees

• 후베이 완런 뉴 에너지 테크놀로지 코.,엘티디.

Dates

Publication Date

20260512

Application Date

20221226

Priority Date

20220824

Claims (10)

1. As a low-temperature lithium-ion battery electrolyte comprising an electrolyte salt and an organic solvent, The above organic solvent comprises a fluorocarboxylate ester, a fluorocarbonate ester, and 1,3-dioxolane; The above fluorocarboxylate ester includes diethyl fluoromalonate; The above fluorocarbonate ester comprises 4-fluoroethylene carbonate; A low-temperature lithium-ion battery electrolyte characterized by the above electrolyte salt containing lithium bis(trifluoromethanesulfonyl)imide.
2. In paragraph 1, A low-temperature lithium-ion battery electrolyte characterized in that, in the above low-temperature lithium-ion battery electrolyte, the volume percentage of the fluorocarboxylate ester is greater than 40%.
3. In paragraph 2, A low-temperature lithium-ion battery electrolyte characterized in that, in the above low-temperature lithium-ion battery electrolyte, the volume percentage of the fluorocarboxylate ester is 50% to 70%.
4. In paragraph 1, A low-temperature lithium-ion battery electrolyte characterized by the volume ratio of the above fluorocarboxylate ester, the above fluorocarbonate ester, and the above 1,3-dioxolane being (90~40):(5~50):(5~30).
5. In paragraph 4, A low-temperature lithium-ion battery electrolyte characterized by the volume ratio of the above fluorocarboxylate ester, the above fluorocarbonate ester, and the above 1,3-dioxolane being (55~65):(15~25):(15~25).
6. In paragraph 1, A low-temperature lithium-ion battery electrolyte characterized in that, in the above low-temperature lithium-ion battery electrolyte, the concentration of the electrolyte salt is 1.0 mol/L to 5.0 mol/L.
7. In paragraph 6, A low-temperature lithium-ion battery electrolyte characterized in that, in the above low-temperature lithium-ion battery electrolyte, the concentration of the electrolyte salt is 1.5 mol/L to 2.5 mol/L.
8. A method for manufacturing a low-temperature lithium-ion battery electrolyte according to any one of claims 1 to 7, A method for manufacturing a low-temperature lithium-ion battery electrolyte characterized by uniformly mixing an organic solvent and an electrolyte salt to obtain the low-temperature lithium-ion battery electrolyte.
9. A lithium-ion battery characterized by including a low-temperature lithium-ion battery electrolyte according to any one of claims 1 to 7.
10. In Paragraph 9, A lithium-ion battery characterized in that the cathode material is lithium iron phosphate.

Description

Low-temperature lithium-ion battery electrolyte, method for manufacturing the same, and lithium-ion battery This application claims priority to a Chinese invention patent application filed on August 24, 2022, with application number 202211016568.3 and title of the invention “low-temperature lithium-ion battery electrolyte and method for manufacturing the same and lithium-ion battery,” the disclosure of said application is incorporated into this specification by reference. The present invention relates to the field of lithium-ion battery technology, and in particular to a low-temperature lithium-ion battery electrolyte, a method for manufacturing the same, and a lithium-ion battery. As the application scope of lithium-ion batteries (LIBs) gradually expands, requirements for low-temperature charge/discharge performance have become increasingly stringent, particularly in applications within the electric vehicle, aerospace, and military sectors. However, there remain significant technical challenges in improving the storage performance and cycle stability of lithium-ion batteries at low temperatures. Specifically, commercial carbonate-based electrolytes tend to solidify easily at low temperatures and exhibit high impedance, which limits their further application in the low-temperature electric vehicle sector. Consequently, electrolyte optimization has become a key research hotspot for improving the low-temperature performance of lithium-ion batteries. Among various cathode materials, lithium iron phosphate (LiP) is widely used in the electric vehicle sector due to its high safety performance and low cost; however, its low conductivity necessitates improvements in low-temperature performance. Therefore, research on adaptive modifications for low-temperature electrolytes when using LiP as a lithium-ion cathode holds significant market prospects. Patent 202111011044.0 discloses a low-temperature lithium-ion battery electrolyte, specifically disclosed that for a high-nickel ternary cathode, it is composed of lithium difluorooxalate borate LiDFOB and a mixed solvent, wherein the concentration of lithium difluorooxalate borate LiDFOB is 0.8 to 1.5 mol/L, and the mixed solvent is a linear carbonate ester, a cyclic carbonate ester, and γ-butyrolactone. The above technical method lowers the melting point of the electrolyte by adding a low-melting point organic solvent γ-butyrolactone to the carbonate ester, which is the basic solvent, thereby improving the low-temperature performance of the lithium-ion battery and enhancing the electrochemical performance of the lithium-ion battery under low-temperature conditions, but there is still room for improvement in the low-temperature resistance of lithium ions. In light of this, the present invention is specifically proposed. Hereinafter, in order to explain the specific embodiments of the present invention or the technical methods of the prior art more clearly, drawings to be used in describing the specific embodiments or prior art are briefly described, and the drawings described below are some embodiments of the present invention, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without creative effort. Figure 1 is a comparison of batteries manufactured using the low-temperature lithium-ion battery electrolyte of Example 7 and the lithium-ion battery electrolyte of Comparative Example 5 of the present invention, respectively, with a charge/discharge voltage of 2.7 to 4.2 V and a discharge capacity at -30°C. Hereinafter, the technical method of the present invention is described clearly and completely together with the drawings and specific embodiments; however, those skilled in the art will understand that the embodiments described below are only some embodiments of the present invention, not all embodiments, and are merely for the purpose of explaining the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, they are performed under ordinary conditions or conditions recommended by the manufacturer. Unless the manufacturer of the reagents or equipment used is specified, they are all ordinary products available on the market. Hereinafter, the low-temperature lithium-ion battery electrolyte of an embodiment of the present invention, the method for manufacturing the same, and the lithium-ion battery will be described in detail. Some embodiments of the present invention are low-temperature lithium-ion battery electrolytes comprising an electrolyte salt and an organic solvent, wherein The organic solvent provides a low-temperature lithium-ion battery electrolyte comprising fluorocarboxylate esters, fluorocarbonate esters, and 1