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CN-122025817-A - High-performance lithium ion battery electrolyte and preparation method thereof

CN122025817ACN 122025817 ACN122025817 ACN 122025817ACN-122025817-A

Abstract

The application discloses a high-performance lithium ion battery electrolyte and a preparation method thereof, and relates to the technical field of lithium ion batteries, wherein the raw materials comprise a composite electrolyte, a composite solvent, an additive and a surface modifier, the content of the additive in the electrolyte is 1.8-4.56%, the additive comprises pentafluorophenyl diethoxy phosphate, 2, 5-dichloro-benzotrifluoride and vinylene carbonate, the composite electrolyte comprises lithium difluorosulfimide, lithium difluorooxalato borate and lithium bis (trifluoromethylsulfonyl) imide, the composite solvent comprises ethylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate and trimethylsilyl acetate, and the surface modifier comprises tetramethyl-tetravinyl siloxane and vinyl-triethoxysilane. The lithium ion battery electrolyte provided by the application has excellent thermal stability and flame retardance.

Inventors

  • LIU FANG
  • HUANG JIHONG
  • SONG FEI
  • HU GUANGYU
  • YU CHAORUN

Assignees

  • 贵州航盛锂能科技有限公司

Dates

Publication Date
20260512
Application Date
20260320

Claims (10)

  1. 1. The high-performance lithium ion battery electrolyte is characterized in that raw materials comprise composite electrolyte, a composite solvent, an additive and a surface modifier, wherein the content of the additive in the electrolyte is 1.8-4.56%; The additive comprises pentafluorophenyl diethoxy phosphate, 2, 5-dichloro-benzotrifluoride and vinylene carbonate, wherein the mass ratio of the pentafluorophenyl diethoxy phosphate to the 2, 5-dichloro-benzotrifluoride to the vinylene carbonate is 1:0.3-0.5:0.8-1.2.
  2. 2. The high-performance lithium ion battery electrolyte as claimed in claim 1, wherein the composite electrolyte comprises 12-18%, 2.5-4.5% and 3-5.5% of lithium difluorosulfimide, lithium difluorooxalato borate and lithium bis (trifluoromethylsulfonyl) imide.
  3. 3. The high-performance lithium ion battery electrolyte according to claim 1, wherein the composite solvent comprises ethylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate and trimethylsilyl acetate in a volume ratio of 1:0.7-1:2.7-3:2-2.2.
  4. 4. The high-performance lithium ion battery electrolyte according to claim 1, wherein the content of the surface modifier in the electrolyte is 1-2%.
  5. 5. The high-performance lithium ion battery electrolyte according to claim 1, wherein the surface modifier comprises tetramethyl-tetravinyl siloxane and vinyl-triethoxysilane in a mass ratio of 1:1.1-1.2.
  6. 6. The high-performance lithium ion battery electrolyte according to claim 1, wherein the pentafluorophenyl diethoxy phosphate is prepared from the following raw materials, by weight, 3.1-6.2 parts of pentafluorobromide, 0.3-0.6 part of magnesium chips, 0.635-1.27 parts of iodine crystals, 3.6-7.2 parts of anhydrous tetrahydrofuran and 4.55-9.1 parts of triethyl phosphate.
  7. 7. The method for preparing the high-performance lithium ion battery electrolyte according to claim 6, wherein the method for preparing the pentafluorophenyl diethoxy phosphate comprises the following steps: 3.1-6.2 parts of pentafluorobromide, 0.3-0.6 part of magnesium scraps, 0.635-1.27 parts of iodine crystals and 3.6-7.2 parts of anhydrous tetrahydrofuran are mixed together, continuously stirred and reacted for 30-50min, then 4.55-9.1 parts of triethyl phosphate is dropwise added into the reaction liquid, the mixture is stirred and refluxed for 14-18h at the temperature of 60-70 ℃, the mixture is cooled to room temperature, n-heptane is added to precipitate magnesium salt, the solution product is obtained by centrifugal filtration, the solution product is subjected to decompression fractionation, the petroleum ether is used for extraction, the lower sediment is obtained after filtration, and the lower sediment is purified by a silica gel column, and the pentafluorophenyl diethoxy phosphate is obtained after vacuum drying.
  8. 8. The high-performance lithium ion battery electrolyte according to claim 1, wherein the mass ratio of the pentafluorophenyl diethoxy phosphate to the 2, 5-dichloro-benzotrifluoride to the vinylene carbonate is 1:0.4:1.
  9. 9. The high-performance lithium ion battery electrolyte according to claim 5, wherein the mass ratio of the tetramethyl-tetravinyl siloxane to the vinyl-triethoxysilane is 1:1.15.
  10. 10. The method for preparing the high-performance lithium ion battery electrolyte according to any one of claims 1 to 9, which is characterized by comprising the following steps: dissolving the composite electrolyte in the composite solvent, stirring uniformly, then adding the surface modifier, stirring for 30-60min, adding the additive, and stirring uniformly to obtain the electrolyte.

Description

High-performance lithium ion battery electrolyte and preparation method thereof Technical Field The application relates to the technical field of lithium ion batteries, in particular to a high-performance lithium ion battery electrolyte and a preparation method thereof. Background Lithium ion batteries have taken a significant role in global energy storage solutions due to their high energy density, long cycle life, and good charge retention capability. With the continuous global promotion of clean energy and sustainable development strategies, the role of lithium ion batteries in future energy structures is becoming more and more important. In addition, lithium ion batteries also play an indispensable role in the high-tech fields of aerospace, military, medical equipment and the like. For example, modern Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs) widely employ lithium ion batteries as power sources to support their high efficiency and zero emission targets. Similarly, renewable energy systems such as solar energy and wind energy also rely on the efficient energy storage capability of lithium ion batteries to balance supply and demand fluctuations and improve energy utilization. The electrolyte plays a critical role in the lithium ion battery, and serves as a core component of a battery system, and plays a core role in that firstly, active ions are dissociated and conveyed to construct a high-efficiency transmission channel to realize directional migration of charges, secondly, a passivation film layer (such as SEI/CEI film) with selective permeability is generated in situ at an electrode interface, so that the structural integrity of the electrode is maintained, irreversible side reactions are inhibited, and furthermore, the ion transmission contact interface is effectively enlarged by fully penetrating a multi-stage pore structure of an electrode active material. The synergistic optimization of these functions creates an ideal reaction environment for the electrochemical energy storage process. During operation of the battery, the composition and quality of the electrolyte determines the efficiency of lithium ion transport and the overall electrochemical stability of the battery. The key bottleneck of the current development of the high specific energy battery is that the traditional LiPF 6-based electrolyte system has obvious thermodynamic instability, corrosive products such as HF, PF5, POF3 and the like are easily generated by hydrolysis, transition metal ions are triggered to dissolve out and cause phase change of a positive electrode structure, meanwhile, PF5 is used as Lewis acid to catalyze an ester solvent to perform disproportionation reaction, the conventional carbonate solvent has serious oxidative decomposition problem under the high pressure condition of more than 4.3V, and the conventional carbonate solvent has low flash point, easy explosion and poor safety performance. Disclosure of Invention The application provides a high-performance lithium ion battery electrolyte and a preparation method thereof in order to provide the lithium ion battery electrolyte with good stability and high safety. The application provides a high-performance lithium ion battery electrolyte, which adopts the following technical scheme: The high-performance lithium ion battery electrolyte is characterized in that raw materials comprise composite electrolyte, a composite solvent, an additive and a surface modifier, wherein the content of the additive in the electrolyte is 1.8-4.56%; The additive comprises pentafluorophenyl diethoxy phosphate, 2, 5-dichloro-benzotrifluoride and vinylene carbonate, wherein the mass ratio of the pentafluorophenyl diethoxy phosphate to the 2, 5-dichloro-benzotrifluoride to the vinylene carbonate is 1:0.3-0.5:0.8-1.2. Preferably, the composite electrolyte comprises 12-18% of lithium difluorosulfimide, 2.5-4.5% of lithium difluorooxalato borate and 3-5.5% of lithium bis (trifluoromethylsulfonyl) imide in the electrolyte. Preferably, the composite solvent comprises ethylene carbonate, fluoroethylene carbonate, methyl trifluoroethyl carbonate and trimethylsilyl acetate, and the volume ratio is 1:0.7-1:2.7-3:2-2.2. Preferably, the surface modifier is present in the electrolyte in an amount of 1-2%. Preferably, the surface modifier comprises tetramethyl-tetravinyl siloxane and vinyl-triethoxysilane, and the mass ratio is 1:1.1-1.2. Preferably, the pentafluorophenyl diethoxy phosphate is prepared from the following raw materials, by weight, 3.1-6.2 parts of pentafluorobromide, 0.3-0.6 part of magnesium chips, 0.635-1.27 parts of iodine crystals, 3.6-7.2 parts of anhydrous tetrahydrofuran and 4.55-9.1 parts of triethyl phosphate. Preferably, the preparation method of the pentafluorophenyl diethoxy phosphate comprises the following steps: 3.1-6.2 parts of pentafluorobromide, 0.3-0.6 part of magnesium scraps, 0.635-1.27 parts of iodine crystals and 3.6-7.2 parts of anhydrous tetra