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CN-122000456-A - Lithium fluorocarbon battery electrolyte, preparation method thereof and lithium fluorocarbon battery

CN122000456ACN 122000456 ACN122000456 ACN 122000456ACN-122000456-A

Abstract

The lithium fluorocarbon battery electrolyte comprises lithium salt, a solvent, an additive metallocene, wherein the metallocene is one or two of cobaltocene and ferrocene, and the electrolyte also reduces the heat generation quantity of the battery and widens the voltage platform of the battery under different discharge multiplying factors on the premise of not losing capacity.

Inventors

  • YANG XIAOFEI
  • LI XIANFENG
  • DU JINLONG
  • XI YAONING
  • MA DI
  • ZHANG HONGZHANG

Assignees

  • 中国科学院大连化学物理研究所

Dates

Publication Date
20260508
Application Date
20241104

Claims (9)

  1. 1. A lithium fluorocarbon battery electrolyte comprising a lithium salt and a solvent, characterized in that: The catalyst also comprises an additive metallocene, wherein the metallocene is one or two of cobaltocene and ferrocene, and is preferably cobaltocene.
  2. 2. The electrolyte of claim 1, wherein: The content of the additive metallocene is 0.1-1.5wt%, preferably 0.5-1.0wt%, more preferably 0.6-0.8wt% of the total mass of the electrolyte.
  3. 3. The electrolyte of claim 1, wherein: The solvent is one or more of ethylene carbonate, methyl ethyl carbonate, fluoroethylene carbonate, propylene carbonate and dimethyl carbonate, preferably one or more of ethylene carbonate, methyl ethyl carbonate and fluoroethylene carbonate, and more preferably the ethylene carbonate/methyl ethyl carbonate/fluoroethylene carbonate is mixed according to the volume ratio of (40-50)/(40-50)/(5-15).
  4. 4. The electrolyte of claim 1, wherein: The lithium salt is one or more than two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethylsulfonyl) imide, preferably the lithium salt is lithium hexafluorophosphate, and the concentration of the lithium salt in the electrolyte is 0.5-2M, preferably 0.8-1.5M, more preferably 1-1.2M.
  5. 5. A method for preparing the electrolyte according to any one of claims 1 to 4, comprising the steps of: 1) Mixing a solvent and lithium salt under the protection of inert atmosphere, and stirring to obtain an electrolyte; 2) Mixing the metallocene with the electrolyte in the step 1) under the protection of inert atmosphere, and stirring to obtain electrolyte after the metallocene is added; stirring the electrolyte for 0-4 hours; inert gases are classified as high purity argon, with purities greater than 99.999% and oxygen and water contents less than 0.01ppm.
  6. 6. A lithium fluorocarbon battery comprising a positive electrode, a negative electrode, an electrolyte and a diaphragm, characterized in that: The positive electrode uses carbon fluoride CF x as an active substance, and the electrolyte is the electrolyte as set forth in any one of claims 1-4.
  7. 7. The battery of claim 6, wherein: The positive electrode takes an aluminum sheet as a current collector, and a composite electrode taking carbon fluoride as an active substance is loaded on the positive electrode; the conductive agent used by the composite electrode is SuperP-10wt% of the total amount of the composite electrode; The binder used by the composite electrode is PVDF, and the content of the binder accounts for 5-10wt% of the total amount of the composite electrode; The amount of the fluorocarbon CF x is 1.5-12.5 mg/cm 2 .
  8. 8. The battery of claim 6, wherein: The battery adopts celgard 2325 as a diaphragm; The negative electrode is a metal lithium sheet; Under the protection of inert atmosphere, sequentially assembling a lithium sheet, electrolyte added with metallocene, a diaphragm and a positive electrode into a lithium metal battery; Electrolyte is injected into the equipped cells.
  9. 9. The battery according to claim 6, wherein the mass ratio of the metallocene to the positive electrode active material in the battery is 0.023 to 0.572.

Description

Lithium fluorocarbon battery electrolyte, preparation method thereof and lithium fluorocarbon battery Technical Field The invention belongs to the technical field of heat generation of lithium batteries, and particularly relates to lithium fluorocarbon battery electrolyte and a lithium fluorocarbon battery with low heat productivity Background Lithium primary cells exhibit high energy densities (> 1000Whkg -1) approaching twice those of lithium ion cells due to their extremely high theoretical specific capacity (3860 mAhg -1) and electrode potential (-3.04vvs. She). Therefore, lithium primary batteries are still widely used in primary battery application fields of portable electronic devices, automotive products, wearable devices, medical devices, aerospace navigation devices, and the like. Among different types of lithium primary batteries, a lithium fluorocarbon battery (Li/CF x) becomes a primary battery energy storage device with great application prospect due to the advantages of high energy density (2180 Wh kg -1), stable discharge platform, low self-discharge rate, wide working temperature, long storage life and the like. Although such a battery has the above advantages, the problem of thermal runaway of the battery pack is particularly prominent under high-rate discharge conditions, and the problem directly affects the structural design and use safety of the battery pack, and whether the problem of thermal runaway is solved or not is a primary problem faced by the lithium fluorocarbon battery. The thermal runaway problem with lithium fluorocarbon batteries is caused by the fact that during discharge, the fluorocarbon bonds break and react with lithium ions, causing a voltage hysteresis accompanied by the formation of large amounts of lithium fluoride, generating a large amount of heat. When the battery works at high temperature, even if the problem of thermal runaway does not occur, the high-temperature environment where the battery core is positioned can have negative influence on the components of the battery, so that the service life of the battery is shortened. Meanwhile, the activity of an electrode material in a high temperature environment is reduced, and the diffusion rate of lithium ions in an electrolyte is also reduced, resulting in a drastic decrease in battery performance, and thus, although the Li/CF x battery has a high capacity and a high voltage, its performance is not satisfactory. Therefore, development of a lithium fluorocarbon battery with low heat generation capacity is needed to meet the use requirements of more application scenes in the future, so as to realize the thermal stability and safety of the battery in discharge at high rate. Disclosure of Invention Aiming at the thermal runaway problem of a lithium carbon fluoride battery, the invention provides an electrolyte which can realize the regulation and control of the heat generating process of the Li/CF x battery by reducing the heating value of the lithium fluoride crystallization process in the electrochemical reaction process in a mode that a great amount of crystal nuclei are generated in advance by chemical reaction of lithium fluoride before the battery is discharged. According to the invention, the metallocene is added into the electrolyte to reduce the positive electrode material, the positive electrode material is induced to generate chemical reaction in advance before discharging, and free lithium fluoride crystal nucleus is generated on the surface of the positive electrode material, so that the nucleation barrier of lithium fluoride is reduced, the surface generation energy of the lithium fluoride is reduced, and the aim of reducing a large amount of heat released by lithium fluoride generated by a Li/CF x battery under high multiplying power is fulfilled. In addition, the electrolyte reduces the voltage platform of the battery under different discharge multiplying factors on the premise of not losing capacity. The invention relates to a lithium fluorocarbon battery electrolyte, which comprises lithium salt and a solvent, and further comprises an additive metallocene, wherein the metallocene is one or two of cobaltocene and ferrocene, and preferably cobaltocene. Further, the content of the additive metallocene is 0.1 to 1.5wt%, preferably 0.5 to 1.0wt%, more preferably 0.6 to 0.8wt% based on the total mass of the electrolyte. Further, the solvent is at least one or more of the lipid electrolytes such as Ethylene Carbonate (EC), ethylmethyl carbonate (EMC), fluoroethylene carbonate (FEC), propylene Carbonate (PC), dimethyl carbonate (DMC), etc., preferably, the solvent added is at least one or more of Ethylene Carbonate (EC), ethylmethyl carbonate (EMC), fluoroethylene carbonate (FEC), more preferably, EC/EMC/FEC is mixed according to a volume ratio = (40-50)/(40-50)/(5-15). Further, the lithium salt is one or more of lithium salts such as lithium hexafluorophosphate (LiPF 6), lithium tetrafluoroborate (LiBF 4)