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CN-122000474-A - Electrolyte and lithium ion battery

CN122000474ACN 122000474 ACN122000474 ACN 122000474ACN-122000474-A

Abstract

The application relates to the technical field of lithium ion batteries, and discloses electrolyte and a lithium ion battery. The electrolyte comprises a carbonate solvent and a carboxylate solvent, wherein the mass ratio of the carbonate solvent to the carboxylate solvent is (7:3) - (9:1), the composite additive comprises a first functional additive and a second functional additive, the composite additive accounts for 2% -8% of the total mass of the electrolyte, the mass ratio of the first functional additive to the second functional additive is (1:10) - (10:1), the first functional additive comprises any one of vinylene carbonate, fluoroethylene carbonate and 1, 3-propane sultone, and the second functional additive comprises at least one of vinyl sulfate and lithium difluorophosphate. The electrolyte disclosed by the application is beneficial to improving the quick charge performance and the electrical performance of the lithium ion battery at low temperature.

Inventors

  • XING CAIHONG
  • LIANG LI
  • WANG MENGRU
  • YI YANYAN
  • ZHANG DINGXIN
  • BAI YING
  • GUO FENGGANG
  • KANG CHUANJIAN
  • XIAO DONGMEI
  • LIANG YAN
  • LI XIAOJIE
  • SUN XIAOMAN
  • WANG YUEYA
  • CHEN YONG

Assignees

  • 北汽福田汽车股份有限公司

Dates

Publication Date
20260508
Application Date
20260209

Claims (10)

  1. 1. An electrolyte solution, which is used for the electrolytic solution, characterized by comprising the following steps: A carbonate solvent and a carboxylate solvent, the mass ratio of the carbonate solvent to the carboxylate solvent being (7:3) - (9:1); The electrolyte comprises a composite additive, wherein the composite additive comprises a first functional additive and a second functional additive, the composite additive accounts for 2% -8% of the total mass of the electrolyte, the mass ratio of the first functional additive to the second functional additive is (1:10) - (10:1), the first functional additive comprises any one of vinylene carbonate, fluoroethylene carbonate and 1, 3-propane sultone, and the second functional additive comprises at least one of vinyl sulfate and lithium difluorophosphate.
  2. 2. The electrolyte according to claim 1, wherein, The carbonate solvent comprises at least two of ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate and diethyl carbonate, and/or, The carboxylic acid ester solvent comprises at least one of ethyl acetate, ethyl propionate and methyl propionate.
  3. 3. The electrolyte according to claim 1, wherein, The first functional additive accounts for 0.3 to 6 percent of the total mass of the electrolyte, and/or, The second functional additive accounts for 0.5% -3% of the total mass of the electrolyte.
  4. 4. The electrolyte according to claim 1, wherein, The ethylene carbonate accounts for 0.5 to 3 percent of the total mass of the electrolyte, and/or, The fluoroethylene carbonate accounts for 0.5% -1.5% of the total mass of the electrolyte, and/or, The 1, 3-propane sultone accounts for 0.5-1% of the total mass of the electrolyte.
  5. 5. The electrolyte according to claim 1, wherein, The ethylene sulfate accounts for 0.5% -1.5% of the total mass of the electrolyte, and/or, The lithium difluorophosphate accounts for 0.2% -1% of the total mass of the electrolyte.
  6. 6. The electrolyte of any one of claims 1-5, further comprising: The lithium salt comprises a first lithium salt and a second lithium salt, the first lithium salt comprises LiPF 6 , the second lithium salt comprises at least one of LiFSI, liTFSI, liBF 4 , and the lithium salt accounts for 8% -20% of the total mass of the electrolyte.
  7. 7. The electrolyte according to claim 6, wherein, The concentration of the first lithium salt is 0.5mol/L to 1.5mol/L, and/or, The concentration of the second lithium salt is 0.05mol/L to 0.5mol/L.
  8. 8. The electrolyte according to claim 6, wherein, The LiFSI accounts for 5 to 50 percent of the total mass of the lithium salt, and/or, The LiTFSI accounts for 2% -25% of the total mass of the lithium salt, and/or, The LiBF 4 accounts for 2% -15% of the total mass of the lithium salt, and/or, The LiPF 6 accounts for 10-80% of the total mass of the lithium salt.
  9. 9. The electrolyte according to any one of claim 1 to 5, wherein, The viscosity of the electrolyte is 0.5-8 mPa-s at a temperature of-30 ℃ to 65 ℃.
  10. 10. A lithium ion battery comprising the electrolyte of any one of claims 1-9.

Description

Electrolyte and lithium ion battery Technical Field The application relates to the technical field of lithium ion batteries, in particular to electrolyte and a lithium ion battery. Background With the continuous popularization of new energy automobile markets, user mileage anxiety becomes a problem which affects the user experience of the new energy automobile and needs to be solved urgently. Under the condition that the battery capacity is relatively limited, the charging multiplying power of the battery system is improved, and the charging time is shortened, so that the method is a key way for solving mileage anxiety. Therefore, improving the fast charge performance of the battery is an urgent need to improve the user experience of the new energy automobile. In addition, in northern areas of China, the battery performance of the new energy automobile is also obviously affected by low temperature in winter. For example, the discharge energy of a lithium iron phosphate (LFP) lithium ion battery at low temperature is obviously reduced, and the popularization and application of new energy automobiles in vast northern areas are severely limited. Therefore, the comprehensive improvement of the performance of the lithium ion battery not only needs to consider the improvement of the quick charge performance of the lithium ion battery, but also needs to consider the charge and discharge capability of the lithium ion battery under the low-temperature condition. The performance of the electrolyte has important influence on the quick charge and low temperature performance of the lithium ion battery, and further research and development are required. It should be noted that the foregoing statements are merely to provide background information related to the present disclosure and may not necessarily constitute prior art. Disclosure of Invention In a first aspect of the application, the application provides an electrolyte, which comprises a carbonate solvent and a carboxylate solvent, wherein the mass ratio of the carbonate solvent to the carboxylate solvent is (7:3) - (9:1), a composite additive comprises a first functional additive and a second functional additive, the composite additive accounts for 2% -8% of the total mass of the electrolyte, the mass ratio of the first functional additive to the second functional additive is (1:10) - (10:1), the first functional additive comprises any one of Vinylene Carbonate (VC), fluoroethylene carbonate (FEC) and 1, 3-Propane Sultone (PS), and the second functional additive comprises at least one of ethylene sulfate (DTD) and lithium difluorophosphate (LiPO 2F2). Therefore, the electrolyte provided by the application has higher low-temperature chemical stability and ionic conductivity, and can improve the low-temperature performance and the quick charge performance of the battery on the premise of considering the service life of the battery. In some embodiments, the carbonate solvent includes at least two of Ethylene Carbonate (EC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), propylene Carbonate (PC), diethyl carbonate (DEC), and/or the carboxylate solvent includes at least one of Ethyl Acetate (EA), ethyl Propionate (EP), methyl Propionate (MP). Therefore, the viscosity of the electrolyte is reduced, the transmission rate of lithium ions in the electrolyte is improved, and the wettability of the electrolyte to the electrode can be improved, so that the cycle performance and the quick charge performance of the lithium ion battery are improved. In some embodiments, the first functional additive comprises 0.3% -6% of the total mass of the electrolyte, and/or the second functional additive comprises 0.5% -3% of the total mass of the electrolyte. Therefore, the functional additive can form SEI films with higher stability with groups in electrolyte such as lithium ions, carboxylic esters and the like. In some embodiments, the vinylene carbonate comprises 0.5% -3% of the total mass of the electrolyte, and/or the fluoroethylene carbonate comprises 0.5% -1.5% of the total mass of the electrolyte, and/or the 1, 3-propane sultone comprises 0.5% -1% of the total mass of the electrolyte. Therefore, the SEI film forming stability and the ion conductivity can be improved, and the cycling stability of the lithium ion battery in the charging and discharging process can be improved. In some embodiments, the vinyl sulfate (DTD) comprises 0.5% to 1.5% of the total mass of the electrolyte, and/or the lithium difluorophosphate (LiPO 2F2) comprises 0.2% to 1% of the total mass of the electrolyte. Therefore, the migration rate of lithium ions in the electrolyte can be improved, and the quick charge performance of the lithium ion battery can be improved. In some embodiments, the electrolyte further comprises a lithium salt, the lithium salt comprising a first lithium salt and a second lithium salt, the first lithium salt comprising LiPF 6, the second lithium salt comprising at least one of