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CN-121983439-A - Flame-retardant high-power double-electric-layer capacitor electrolyte suitable for energy storage scene and double-electric-layer capacitor containing same

CN121983439ACN 121983439 ACN121983439 ACN 121983439ACN-121983439-A

Abstract

The invention relates to the field of electrochemical energy storage devices, and discloses an electrolyte of a flame-retardant high-power double-layer capacitor suitable for an energy storage scene and a double-layer capacitor containing the same, wherein the electrolyte comprises a liquid-phase flame retardant, a gas-phase flame retardant, a diluent and optional additives besides a solvent and electrolyte salt forming the electrolyte; the liquid-phase flame retardant is a macromolecular fluorinated siloxane compound with a six-membered or eight-membered silicon-oxygen ring as a framework, the gas-phase flame retardant is a halogenated phosphazene compound, the diluent is a fluorinated ether diluent, and the additive is a silazane additive. The electrolyte provided by the invention has the advantages that through the collaborative design of a gas-liquid dual-phase flame-retardant system, the potential safety hazard of easy injection combustion caused by low flash point and thermal runaway of the traditional acetonitrile-based electrolyte is greatly solved, the economy and the process feasibility of large-scale mass production are ensured while the high safety, the long service life and the high energy density are ensured, and the electrolyte is especially suitable for a large-scale energy storage scene with strict safety requirements.

Inventors

  • LI XIAOQING
  • ZHU JINGHUI
  • TANG ZHENG
  • Li Anyue
  • Jiang Minlian
  • XIE TIAN

Assignees

  • 深圳市今朝时代股份有限公司

Dates

Publication Date
20260505
Application Date
20260302

Claims (10)

  1. 1. The electrolyte for the flame-retardant high-power double-electric-layer capacitor suitable for the energy storage scene is characterized by comprising a liquid-phase flame retardant, a gas-phase flame retardant, a diluent and optional additives besides a solvent and electrolyte salt which form the electrolyte, The liquid-phase flame retardant is a macromolecular fluorosilicone compound with a six-membered or eight-membered silicon-oxygen ring as a framework; The gas phase flame retardant is halogenated phosphazene alkane compound; the diluent is fluoroether diluent; the additive is silazane additives.
  2. 2. The electrolyte according to claim 1, wherein the liquid phase flame retardant is a macromolecular fluorosilicone compound having a six-membered or eight-membered silicon-oxygen ring as a skeleton and a benzene ring or a flame-retardant halogen alkyl group in a side chain of which a carbon layer is easily formed; Preferably, the liquid phase flame retardant is at least one selected from 1,3, 5-tris [ (3, 3-trifluoropropyl) methyl ] cyclotrisiloxane (TFTS), tetramethyl tri-3-trifluoropropyl cyclotrisiloxane (TMTS) and tetramethyl tetraphenyl cyclotrisiloxane (TMTPS); more preferably, the liquid phase flame retardant is TMTS.
  3. 3. The electrolyte according to claim 1 or 2, wherein the liquid phase flame retardant is added in an amount of 1 to 10% by mass of the total mass of the solvent and the electrolyte salt constituting the electrolyte.
  4. 4. The electrolyte according to claim 1, wherein the gas phase flame retardant is at least one selected from the group consisting of trifluoroethoxy (pentafluoro) cyclotriphosphazene (TFPN), hexa (2, 2-trifluoroethoxy) cyclotriphosphazene (HFEPN), ethoxy (pentafluoro) cyclotriphosphazene (PFPN), hexafluorocyclotriphosphazene (HFPN), hexachlorocyclotriphosphazene (HCCP), pentafluoro (phenoxy) cyclotriphosphazene (FPPN), preferably TFPN; Preferably, the addition mass of the gas-phase flame retardant accounts for 1-10% of the total mass of the solvent and the electrolyte salt constituting the electrolyte.
  5. 5. The electrolyte according to claim 1, wherein, the diluent is selected from 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether (TTE), 3-methoxy perfluoro (2-methylpentane (MME), perfluorobutyl methyl ether (HFE), ethylnonafluorobutyl ether (HFE-7200), and at least one of methyl nonafluorohexyl ether (HFE-7300), methyl nonafluoropropyl ether (HFE-7000), bis (2-fluoroethoxy) methane (BFME), 1,2, 3-hexafluoropropylene ether (HFME), preferably HFE; preferably, the diluent is added in an amount of 10 to 30% by mass of the total mass of the solvent and the electrolyte salt constituting the electrolyte.
  6. 6. The electrolyte according to claim 4, wherein the additive is at least one selected from the group consisting of hexamethyl cyclotrisilazane (HTMS), hexamethyldisilazane (HDMS), heptamethyldisilazane (H7 DMS), octamethyl cyclotetrasilazane (OMCTS), and Tetramethyldisilazane (TMDS); Preferably, the additive is added in an amount of 0.1 to 2.0% by mass of the total mass of the solvent and the electrolyte salt constituting the electrolyte.
  7. 7. The electrolyte according to claim 1, wherein the electrolyte salt is at least one of 1, 1-dimethylpyrrolidine tetrafluoroborate (DMP BF 4 ), tetraethylenetetrafluoroborate (TEA BF 4 ), spiro- (1, 1') -dipyrrolidine tetrafluoroborate (SBP BF 4 ), 1-ethyl-3-methylimidazole tetrafluoroborate (EMI BF 4 ), 1-ethyl-3-methylimidazole bis (fluorosulfonyl) imide salt (EMIm FSI), preferably DMP BF 4 .
  8. 8. The electrolyte of claim 7, wherein the concentration of the electrolyte salt is 0.5mol/L to 1.5mol/L.
  9. 9. Electrolyte according to claim 1, characterized in that the solvent constituting the electrolyte is selected from at least one of Acetonitrile (AN), propionitrile (PN), valeronitrile (VN), 3-Methoxypropionitrile (MPN), adiponitrile (ADN), propylene Carbonate (PC), ethylene Carbonate (EC), preferably AN.
  10. 10. An electric double layer capacitor, characterized by comprising the electrolyte of the flame-retardant high-power electric double layer capacitor suitable for energy storage scenes according to any one of claims 1to 9.

Description

Flame-retardant high-power double-electric-layer capacitor electrolyte suitable for energy storage scene and double-electric-layer capacitor containing same Technical Field The invention belongs to the field of energy storage devices, and particularly relates to a flame-retardant high-power double-electric-layer capacitor electrolyte suitable for an energy storage scene and a double-electric-layer capacitor containing the same. Background In the prior art, commercial Electric Double Layer Capacitor (EDLC) mass production systems commonly use pure Acetonitrile (AN) as a single solvent to dissolve quaternary ammonium salts (e.g., TEA BF 4) to form standard electrolytes. The system has the advantages of low viscosity and high ionic conductivity, but has intrinsic safety defect, and is characterized in that the AN solvent flash point is extremely low (about 6 ℃), the boiling point is only 82 ℃, the explosion limit range is wide, and once overcharge, short circuit or thermal runaway occurs in large-scale application scenes such as energy storage power stations, port machinery and the like, flammable vapor cloud is formed extremely easily, deflagration accidents are caused, and the application of the EDLC in the energy storage field is severely restricted. In addition, AN has poor chemical stability in high temperature environments (65 ℃ and above), and high temperature load life is often difficult to meet long term energy storage requirements. In addition, the existing high-safety electrolyte technology often replaces AN by introducing a high-viscosity flame-retardant solvent, so that the flash point is increased, but the ion transmission rate is obviously sacrificed, the power density is greatly reduced, and the bottleneck that the safety and the electrochemical performance are not compatible is formed. CN121439535A discloses a power type additive of AN electric double layer capacitor electrolyte, the electrolyte comprises AN organic solvent, AN electrolyte salt and AN additive, wherein the electrolyte salt is at least one of tetraethylammonium tetrafluoroborate (TEA BF 4), spiro- (1, 1') -dipyrrolidine tetrafluoroborate (SBP BF 4), 1-dimethylpyrrolidine tetrafluoroborate (DMP BF 4), 1-ethyl-3-methylimidazole tetrafluoroborate (EMIm BF 4) and 1-ethyl-3-methylimidazole bis (fluorosulfonyl) imide salt (EMIm FSI), the organic solvent is at least one of Propylene Carbonate (PC) electrolyte, ethylene Carbonate (EC) electrolyte, acetonitrile (AN), N-Dimethylformamide (DMF), and the additive has a general structure of formula I, and the preferable additive structure is 3, 3-trifluoropropyl methyldimethoxysilane. An Electric Double Layer Capacitor (EDLC) comprising the electrolyte has a capacity retention rate increased from 76.3% to 90.1% in 125A high rate cycle (conventional current 25A). In addition, the silicon-containing part formed by bond breaking can also cooperatively remove HF generated by the hydrolysis of salt anions BF 4-in the electrolyte and passivate Al foil, so that the contact internal resistance of the aluminum conductor is reduced. The patent achieves a reduction in internal resistance of liquid phase transmission and high power performance, but cannot achieve both safety and electrochemical performance. I is a kind of Therefore, there is a need in the industry for an electrolyte for a high power electric double layer capacitor that combines both safety and electrochemical performance. Disclosure of Invention In order to solve the defects in the prior art, the invention provides the electrolyte of the flame-retardant high-power double-electric-layer capacitor, which can achieve both safety and electrochemical performance. Another object of the present invention is to provide the use of the electrolyte for such flame retardant high power electric double layer capacitors. In order to achieve the aim of the invention, the invention adopts the following technical scheme: the electrolyte for the flame-retardant high-power double-electric-layer capacitor suitable for the energy storage scene comprises a liquid-phase flame retardant, a gas-phase flame retardant, a diluent and optional additives besides a solvent and electrolyte salt which form the electrolyte, The liquid-phase flame retardant is a macromolecular fluorosilicone compound with a six-membered or eight-membered silicon-oxygen ring as a framework; The gas phase flame retardant is halogenated phosphazene alkane compound; the diluent is fluoroether diluent; the additive is silazane additives. In some specific embodiments, the liquid phase flame retardant is a macromolecular fluorosilicone compound which has a six-membered or eight-membered silicon-oxygen ring as a framework and side chains of which contain benzene rings or flame-retardant halogen alkyl groups which are easy to form carbon layers; Preferably, the liquid phase flame retardant is at least one selected from 1,3, 5-tris [ (3, 3-trifluoropropyl) methyl ] cyclotrisiloxane (TFTS), tetrame