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CN-122000468-A - High-temperature-resistant electrolyte and lithium ion battery

CN122000468ACN 122000468 ACN122000468 ACN 122000468ACN-122000468-A

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a high-temperature-resistant electrolyte and a lithium ion battery. The high-temperature-resistant electrolyte comprises lithium salt, an organic solvent, a film-forming additive and a high-temperature-resistant additive, wherein the content of the high-temperature-resistant additive is 1-5% based on 100% of the total mass of the high-temperature-resistant electrolyte, and the high-temperature-resistant additive is selected from the combination of diphenylphosphinoyl hydroxylamine and phenylphosphononitrile. According to the high-temperature-resistant electrolyte provided by the invention, the high-temperature-resistant additive is introduced, so that a stable and compact SEI film can be formed on the surface of the negative electrode, the growth of dendrites is inhibited, the loss of active lithium is reduced, and meanwhile, a high-temperature-resistant protective layer is formed on the positive electrode side, so that the oxidation stability of a positive electrode interface is effectively improved, the electrode interface has compactness and heat resistance, the interface stability at high temperature is obviously improved, and a battery using the high-temperature-resistant SEI film has excellent high-temperature cycle performance.

Inventors

  • ZHAO YALI
  • LIU YUTAO
  • Gong Xuanlin
  • LIU JIARUI
  • CHEN BAOHUI
  • WU CHUANPING

Assignees

  • 国网湖南省电力有限公司防灾减灾中心
  • 国网湖南省电力有限公司
  • 国家电网有限公司

Dates

Publication Date
20260508
Application Date
20260205

Claims (10)

  1. 1. The high-temperature-resistant electrolyte is characterized by comprising lithium salt, an organic solvent, a film-forming additive and a high-temperature-resistant additive; the content of the high-temperature resistant additive is 1-5% based on 100% of the total mass of the high-temperature resistant electrolyte; the high temperature resistant additive is selected from the group consisting of diphenylphosphinoylhydroxylamine and phenylphosphononitrile.
  2. 2. The high temperature resistant electrolyte according to claim 1, wherein the mass ratio of diphenylphosphinoyl hydroxylamine to phenylphosphononitrile is1 (0.8-1.5), preferably 1 (1-1.2).
  3. 3. The high temperature resistant electrolyte of claim 1 or 2, wherein the film forming additive comprises any one or more of fluoroethylene carbonate, vinylene carbonate, vinyl sulfate, and lithium difluorophosphate.
  4. 4. A high temperature resistant electrolyte according to claim 3 wherein the film forming additive is selected from the group consisting of vinylene carbonate, lithium difluorophosphate and fluoroethylene carbonate; preferably, the mass ratio of the vinylene carbonate to the lithium difluorophosphate to the fluoroethylene carbonate is 1 (0.5-1): 0.5-1.
  5. 5. The high temperature resistant electrolyte according to any one of claims 1 to 4, wherein the content of the film forming additive is 2 to 6% based on 100% of the total mass of the high temperature resistant electrolyte.
  6. 6. The high temperature resistant electrolyte of any one of claims 1-5 wherein the lithium salt comprises any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate and lithium difluorosulfonimide.
  7. 7. The high-temperature resistant electrolyte according to any one of claims 1 to 6, wherein the content of the lithium salt is 11 to 15% based on 100% of the total mass of the high-temperature resistant electrolyte.
  8. 8. The high temperature resistant electrolyte according to any one of claims 1 to 7, wherein the organic solvent comprises any one or more of ethyl acetate, propyl acetate, butyl acetate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, and ethylmethyl carbonate.
  9. 9. The high temperature resistant electrolyte according to any one of claims 1 to 8, wherein the content of the organic solvent is 75 to 85% based on 100% of the total mass of the high temperature resistant electrolyte.
  10. 10. A lithium ion battery comprising the high temperature resistant electrolyte of any one of claims 1-9.

Description

High-temperature-resistant electrolyte and lithium ion battery Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a high-temperature-resistant electrolyte and a lithium ion battery. Background Lithium ion batteries are currently the most representative secondary battery systems, and play a central role in the fields of new energy automobiles, smart grids, portable electronic products and the like by virtue of high specific energy, long cycle life and excellent energy conversion efficiency. However, as applications thereof are gradually expanded to extreme environments and high-load scenes, such as power system operation under high-temperature weather, deep petroleum and natural gas exploration, energy supply of aerospace equipment and the like, stability and safety problems of batteries under high-temperature conditions are increasingly highlighted. In particular, in environments with temperatures exceeding 60 ℃, the traditional carbonate-based electrolyte system generally has multiple challenges, namely firstly, the thermal decomposition reaction of a conventional solvent is aggravated, gas and byproducts are easy to generate, the abnormal changes of the viscosity and the conductivity of the electrolyte are caused, the thermal runaway risk is possibly induced, secondly, common lithium salts such as lithium hexafluorophosphate and the like are extremely easy to decompose at high temperature, generated corrosive substances such as HF and the like can damage an electrode/electrolyte interface, the service life of a battery is obviously shortened, furthermore, an SEI film of a negative electrode is unstable in the high-temperature environment, cracking and repeated repair cycles are easy to occur, active lithium is continuously consumed, and electrolyte oxidation reaction can also occur on the surface of a positive electrode material to form a high-impedance layer, so that lithium ion transmission and energy efficiency are seriously hindered. The above problems are superimposed, which not only reduces the cycling stability of the battery, but also threatens the safe operation of the large-scale energy storage and power battery system. Therefore, the development of new high temperature electrolyte systems has become a common direction of research emphasis and industry demand. At present, the feasible improvement strategies comprise (1) introducing a solvent with higher thermal decomposition temperature and better chemical inertia through molecular design, fundamentally improving the thermal stability of electrolyte, (2) screening and optimizing high-temperature-resistant lithium salt, thereby guaranteeing the long cycle life and safe operation of a battery, and (3) constructing a compact and heat-resistant interface film layer on the surface of an electrode through adding a film forming agent and a high Wen Gongneng additive, thereby effectively inhibiting side reaction and stabilizing an interface structure. Although some researches have been conducted to explore the application of additives such as fluorinated solvents and dianion salts, the problems of high cost, insufficient system compatibility, poor long-term thermal stability and the like still exist. Therefore, how to construct a brand new electrolyte system facing high-temperature application while maintaining high ionic conductivity and achieving excellent interface stability and thermal decomposition resistance becomes a key problem of urgent need for breakthrough. Disclosure of Invention In order to solve the technical problems, the invention provides a high-temperature-resistant electrolyte and a lithium ion battery. According to the high-temperature-resistant electrolyte provided by the invention, the high-temperature-resistant additive is introduced, so that a stable and compact SEI film can be formed on the surface of the negative electrode, the growth of dendrites is inhibited, the loss of active lithium is reduced, and meanwhile, a high-temperature-resistant protective layer is formed on the positive electrode side, so that the oxidation stability of a positive electrode interface is effectively improved, the electrode interface has compactness and heat resistance, the interface stability at high temperature is obviously improved, and a battery using the high-temperature-resistant SEI film has excellent high-temperature cycle performance. In a first aspect, the present invention provides a high temperature resistant electrolyte comprising a lithium salt, an organic solvent, a film forming additive, and a high temperature resistant additive; The content of the high-temperature resistant additive is 1 to 5%, for example, 1%, 2%, 3%, 4%, 5%, etc., based on 100% of the total mass of the high-temperature resistant electrolyte; the high temperature resistant additive is selected from the group consisting of diphenylphosphinoylhydroxylamine and phenylphosphononitrile. The high-temperature-resistant