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CN-122025827-A - Preparation method of electrolyte with high interface stability and application of electrolyte in lithium ion battery

CN122025827ACN 122025827 ACN122025827 ACN 122025827ACN-122025827-A

Abstract

A preparation method of electrolyte with high interface stability and application thereof in lithium ion batteries relate to a preparation method and application of electrolyte. Adding lithium bistrifluoro methanesulfonimide into ethyl acetate, stirring and dissolving, then adding fluoroethylene carbonate, continuously stirring, finally adding tetrahydrofuran, and stirring for a period of time to obtain the electrolyte with high interface stability. According to the invention, an EA-FEC-THF ternary synergistic solvation system is constructed by introducing tetrahydrofuran to regulate and control an electrolyte solvation structure, so that a solvation sheath layer of Li + is optimized, the lithium ion migration capacity is improved while the solvation structure stability is ensured, and the reduction side reaction of an ester solvent at a graphite negative electrode interface can be effectively reduced under the condition of a proper amount of THF, so that the formation of a stable and compact SEI film is promoted, and the stability of an electrode/electrolyte interface is remarkably improved.

Inventors

  • CHEN MINGHUA
  • JIANG GUANGQUAN
  • LI YU
  • ZHANG JIAWEI
  • WANG FAN
  • LIANG XINQI
  • LIU XIN

Assignees

  • 哈尔滨理工大学

Dates

Publication Date
20260512
Application Date
20260408

Claims (10)

  1. 1. The preparation method of the electrolyte with high interface stability is characterized by comprising the following steps: Adding lithium bistrifluoromethylsulfonyl imide into ethyl acetate, stirring and dissolving, then adding fluoroethylene carbonate, continuously stirring, finally adding tetrahydrofuran, and stirring for a period of time to obtain an electrolyte with high interface stability; the volume ratio of the ethyl acetate to the fluoroethylene carbonate to the tetrahydrofuran is 85:15 (0-50).
  2. 2. The method for preparing the electrolyte with high interfacial stability according to claim 1, wherein the preparation is performed in a glove box, and H 2 O＜0.01ppm,O 2 in the glove box is less than 0.01ppm.
  3. 3. The method for preparing the electrolyte with high interface stability according to claim 1, wherein the volume ratio of the ethyl acetate to the fluoroethylene carbonate to the tetrahydrofuran is 85:15:0.
  4. 4. The method for preparing the electrolyte with high interface stability according to claim 1, wherein the volume ratio of the ethyl acetate to the fluoroethylene carbonate to the tetrahydrofuran is 85:15:10.
  5. 5. The method for preparing the electrolyte with high interface stability according to claim 1, wherein the volume ratio of the ethyl acetate to the fluoroethylene carbonate to the tetrahydrofuran is 85:15:30.
  6. 6. The method for preparing the electrolyte with high interface stability according to claim 1, wherein the volume ratio of the ethyl acetate to the fluoroethylene carbonate to the tetrahydrofuran is 85:15:50.
  7. 7. The method for preparing the electrolyte with high interface stability according to claim 1, wherein the stirring time is 10-120 min.
  8. 8. The preparation method of the electrolyte with high interface stability, which is characterized in that the concentration of the lithium bis (trifluoromethanesulfonyl) imide in the electrolyte with high interface stability is 0.8 mol/L-1.2 mol/L.
  9. 9. The method for preparing the electrolyte with high interface stability according to claim 8, wherein the concentration of the lithium bis (trifluoromethanesulfonyl) imide in the electrolyte with high interface stability is 1mol/L.
  10. 10. The use of the high interfacial stability electrolyte prepared by the method of preparation of claim 1, wherein the high interfacial stability electrolyte is used in a lithium ion battery.

Description

Preparation method of electrolyte with high interface stability and application of electrolyte in lithium ion battery Technical Field The invention relates to a preparation method and application of an electrolyte, in particular to a preparation method of an electrolyte with high interface stability and application of the electrolyte in a lithium ion battery. Background With the rapid development of new energy industry, lithium iron phosphate// graphite (LFP// GR) lithium ion batteries are widely applied to the fields of electric automobiles and energy storage due to high safety, long cycle life and remarkable cost advantages. However, the existing commercial electrolyte generally adopts a carbonate system mainly comprising Ethylene Carbonate (EC), and a series of problems still need to be solved in the practical application process. For example, under the conditions of medium-high multiplying power or low temperature, the EC-based electrolyte has higher viscosity, limited lithium ion transmission kinetics and easy increase of battery polarization, and meanwhile, the graphite negative electrode interface has active side reaction, the solid electrolyte interface film (SEI) has unstable composition, and further capacity attenuation and cycle life reduction are caused. In addition, as the requirements of the battery on high-power performance and wide-temperature-range operation are continuously improved, the problems that the conductivity of the traditional commercial electrolyte is obviously reduced, the interface impedance is increased and the like easily occur in a low-temperature environment are difficult to meet the requirements of actual working conditions. Therefore, development of an electrolyte system having both good lithium ion transport performance, stable interfacial chemical properties and excellent cycle stability has become an important research direction in the field of lithium ion batteries. In recent years, electrolyte systems using LiTFSI as a lithium salt, low-viscosity ester or ether solvents as a main body are attracting attention, but the problems of solvent co-intercalation and interfacial stability in graphite cathodes still limit the application thereof. Tetrahydrofuran (THF) can be used as a low-viscosity ether solvent to regulate and control a lithium ion solvation structure, but the influence rule of the addition amount of the Tetrahydrofuran (THF) on solvated sheath configuration, electrode interface stability and electrochemical performance of a battery is not clear. Disclosure of Invention In order to solve the technical problems, the invention provides a preparation method of an electrolyte with high interface stability and application of the electrolyte in a lithium ion battery. According to the invention, through gradient regulation and control of Tetrahydrofuran (THF) addition proportion, a solvation structure evolution rule of an EA-FEC-THF ternary solvent system is systematically researched, a novel electrolyte system with high ionic conductivity and interface stability is constructed, meanwhile, interface compatibility of a graphite negative electrode and a lithium iron phosphate positive electrode is considered, an optimal proportioning scheme is finally screened out, and a technical scheme with performance superior to that of the conventional commercial electrolyte is provided for an LFP// GR battery. The preparation method of the electrolyte with high interface stability comprises the following steps: Adding lithium bistrifluoromethylsulfonyl imide into ethyl acetate, stirring and dissolving, then adding fluoroethylene carbonate, continuously stirring, finally adding tetrahydrofuran, and stirring for a period of time to obtain an electrolyte with high interface stability; the volume ratio of the ethyl acetate to the fluoroethylene carbonate to the tetrahydrofuran is 85:15 (0-50). The invention has the advantages that: (1) According to the invention, tetrahydrofuran (THF) is introduced to regulate and control the solvation structure of the electrolyte, so that an EA-FEC-THF ternary synergistic solvation system is constructed, the solvation sheath composition of Li + is optimized, the stability of the solvation structure is ensured, and the migration capacity of lithium ions is improved; (2) Under the condition of a proper amount of THF (preferably 10% by volume), the reduction side reaction of the ester solvent at the interface of the graphite negative electrode can be effectively reduced, and the stable and compact SEI film can be promoted to be formed, so that the stability of the electrode/electrolyte interface is obviously improved; (3) Compared with commercial carbonate electrolyte, the electrolyte of the invention shows more excellent electrochemical performance under the conditions of high multiplying power, long circulation and low temperature, and is particularly characterized by higher capacity retention rate, lower interface impedance and more stable circula