Search

CN-122025806-A - Electrolyte additive, electrolyte and secondary battery

CN122025806ACN 122025806 ACN122025806 ACN 122025806ACN-122025806-A

Abstract

The invention relates to the technical field of batteries, in particular to an electrolyte additive, electrolyte and a secondary battery. The electrolyte additive comprises a fluorosulfonate compound and an ionic liquid, wherein the fluorosulfonate compound has a structural formula as shown in (I), and the ionic liquid has a structural formula as shown in (II): (I) Wherein R1, R2 and R3 are each independently selected from the group consisting of the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted unsaturated hydrocarbon group and substituted or unsubstituted aryl group, and X ‑ is selected from any one of fluorine-containing anions. According to the invention, the fluorosulfonate compound in the electrolyte additive and the ionic liquid are matched mutually, so that the stable operation of the battery in a wide temperature range can be effectively improved, and the low-temperature discharge performance and the high-temperature cycle performance are both considered.

Inventors

  • YAO YUAN
  • QIN BINGSHENG
  • SHENG JIE

Assignees

  • 蜂巢能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260113

Claims (10)

  1. 1. An electrolyte additive is characterized by comprising a fluorosulfonate compound and an ionic liquid; The fluorosulfonate compound has a structural formula as shown in (I), and the ionic liquid has a structural formula as shown in (II): (I) (II); Wherein R1, R2 and R3 are each independently selected from the group consisting of the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted unsaturated hydrocarbon group and substituted or unsubstituted aryl group, and X - is selected from any one of fluorine-containing anions.
  2. 2. The electrolyte additive according to claim 1, wherein a substituent of at least one of the substituted alkyl group, the substituted silyl group, the substituted unsaturated hydrocarbon group, and the substituted aryl group is selected from halogen or cyano.
  3. 3. The electrolyte additive of claim 1 wherein the fluorine-containing anion comprises at least one of tetrafluoroborate, hexafluorophosphate, bis-fluorosulfonyl imide anion, bis (trifluoromethylsulfonyl) imide anion, and trifluoromethylsulfonic acid anion.
  4. 4. The electrolyte additive according to any one of claims 1 to 3, wherein the fluorosulfonate compound comprises at least one of (I-1) to (I-4): (I-1) (I-2) (I-3) (I-4)。
  5. 5. the electrolyte additive according to any one of claims 1 to 3, wherein the ionic liquid comprises at least one of (II-1) to (II-4): (II-1) (II-2) (II-3) (II-4)。
  6. 6. An electrolyte, which is characterized by comprising electrolyte salt, solvent and the electrolyte additive of any one of claims 1-5; and/or the mass ratio of the fluorosulfonate compound to the ionic liquid in the electrolyte additive is 1 (0.2-3.5); and/or the electrolyte salt comprises a lithium salt or a sodium salt; and/or the solvent comprises at least one of a carbonate compound and a carboxylate compound.
  7. 7. The electrolyte according to claim 6, wherein at least one of the characteristics (1) to (9) is satisfied: (1) The lithium salt comprises at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium trifluoromethylsulfonate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (oxalato) borate, lithium difluorooxalato borate, lithium difluorophosphate and lithium difluorodioxaato phosphate; (2) The sodium salt comprises at least one of sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium difluorosulfimide, sodium bis (trifluoromethylsulfonyl) imide, sodium dioxalate borate, sodium difluorooxalate borate, sodium difluorophosphate and sodium difluorodioxalate phosphate; (3) The carbonate compound comprises at least one of cyclic carbonate and chain carbonate; (4) The carboxylic ester compound comprises at least one of fluorinated carboxylic ester and carboxylic ester; (5) Based on the total mass of the electrolyte, the mass ratio of the fluorosulfonate compounds is 0.2% -1.5%; (6) Based on the total mass of the electrolyte, the mass ratio of the ionic liquid is 0.5% -8%; (7) Based on the total mass of the electrolyte, the mass ratio of the carbonate compound is 20% -70%; (8) Based on the total mass of the electrolyte, the mass ratio of the carboxylate compound is 30% -80%; (9) The concentration of the electrolyte salt in the electrolyte is 0.4 mol/L-3 mol/L.
  8. 8. The electrolyte of claim 6, further comprising a second additive; the second additive comprises at least one of sulfite compounds, sulfonate compounds, carbonate compounds and sulfate compounds.
  9. 9. The electrolyte according to claim 7 or 8, wherein at least one of the features (1) to (9) is satisfied: (1) The cyclic carbonate includes at least one of ethylene carbonate, propylene carbonate, and fluoroethylene carbonate; (2) The chain carbonate includes at least one of fluorine substituted or unsubstituted dimethyl carbonate, fluorine substituted or unsubstituted diethyl carbonate, fluorine substituted or unsubstituted dipropyl carbonate, fluorine substituted or unsubstituted methylethyl carbonate, fluorine substituted or unsubstituted methylpropyl carbonate, and fluorine substituted or unsubstituted ethylpropyl carbonate; (3) The fluorocarboxylic acid ester includes at least one of fluorine substituted ethyl acetate, fluorine substituted n-propyl acetate, fluorine substituted isopropyl acetate, fluorine substituted butyl acetate, fluorine substituted isobutyl acetate, fluorine substituted ethyl propionate, fluorine substituted propyl propionate, fluorine substituted butyl propionate, fluorine substituted isobutyl propionate, fluorine substituted ethyl n-butyrate and fluorine substituted ethyl isobutyrate; (4) The carboxylic acid ester comprises at least one of ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, ethyl n-butyrate and ethyl isobutyrate; (5) The sulfite compound comprises at least one of ethylene sulfite and propylene sulfite; (6) The sulfonate compound comprises at least one of 1, 3-propane sultone, 1, 4-butane sultone and 1, 3-propylene sultone; (7) The carbonate compound comprises at least one of vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate and diphenyl carbonate; (8) The sulfate compound comprises vinyl sulfate; (9) Based on the total mass of the electrolyte, the second additive accounts for 0% -10% of the total mass of the electrolyte.
  10. 10. A secondary battery is characterized by comprising a positive electrode plate, a negative electrode plate and the electrolyte as set forth in any one of claims 6-9; the positive electrode plate comprises a first positive electrode active material or a second positive electrode active material, and the negative electrode plate comprises a first negative electrode active material or a second negative electrode active material; and/or the first positive electrode active material comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium cobaltate, lithium manganate, lithium-rich manganese-based material, lithium nickel cobalt manganate and lithium nickel cobalt aluminate; And/or the first anode active material includes at least one of graphite, soft carbon, hard carbon, silicon, and lithium titanate; and/or the second positive electrode active material comprises at least one of sodium copper iron manganese, sodium nickel iron manganese, sodium vanadium phosphate, sodium vanadium fluorophosphate, sodium iron pyrophosphate, sodium iron sulfate and modified sodium ferrocyanide; and/or the second anode active material includes at least one of soft carbon, hard carbon, and sodium titanate.

Description

Electrolyte additive, electrolyte and secondary battery Technical Field The application relates to the technical field of batteries, in particular to an electrolyte additive, electrolyte and a secondary battery. Background At present, low-temperature and high-temperature-oriented electrolytes are all put into use, but the electrolytes compatible with a wide temperature range still have some problems. The problems of low conductivity, high viscosity and the like of the electrolyte affect the normal performance of the battery capacity at low temperature, the desolvation energy of lithium ions is high, the migration resistance of lithium ions is high, if solvents with low boiling point and low viscosity such as nitriles or short-chain carbonates are selected, a stable interfacial film is difficult to form on the surface of a negative electrode, and meanwhile, the electrolyte is easy to volatilize, and the oxidation resistance is insufficient, so that the gas production of the battery at high temperature can be increased. At high temperatures, exacerbation of side reactions can lead to continued consumption of electrolyte, continued thickening of interfacial films, and severe battery gassing, additives can be used to inhibit gassing, stabilize the positive electrode interface, but such additives are often accompanied by side effects that increase impedance. In order to solve the above problems, it is necessary to develop an electrolyte additive and an electrolyte which can achieve both high and low temperature performance. Disclosure of Invention In view of the above, the present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the electrolyte additive, the electrolyte and the secondary battery provided by the invention can effectively improve the stable operation of the battery in a wide temperature range and consider both the low-temperature discharge performance and the high-temperature cycle performance through the mutual cooperative cooperation of the fluorosulfonate compounds and the ionic liquid in the electrolyte additive. In order to solve the technical problems, the invention is realized as follows: according to one aspect of the invention, the invention provides an electrolyte additive comprising a fluorosulfonate compound and an ionic liquid; The fluorosulfonate compound has a structural formula as shown in (I), and the ionic liquid has a structural formula as shown in (II): (I)(II); Wherein R1, R2 and R3 are each independently selected from the group consisting of the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted unsaturated hydrocarbon group and substituted or unsubstituted aryl group, and X - is selected from any one of fluorine-containing anions. In some of these embodiments, the substituent of at least one of the substituted alkyl, the substituted silyl, the substituted unsaturated hydrocarbyl, and the substituted aryl is selected from halogen or cyano. In some embodiments thereof, the fluoride-containing anions include at least one of tetrafluoroborate, hexafluorophosphate, bis-fluorosulfonyl imide anions, bis (trifluoromethylsulfonyl) imide anions, and trifluoromethylsulfonic acid anions. In some embodiments, the fluorosulfonate compound includes at least one of (I-1) to (I-4): (I-1) (I-2) (I-3)(I-4)。 in some embodiments, the ionic liquid comprises at least one of (II-1) to (II-4): (II-1) (II-2) (II-3)(II-4)。 According to another aspect of the invention, the invention also provides an electrolyte comprising an electrolyte salt, a solvent and an electrolyte additive as described in any of the embodiments above. In some embodiments, the mass ratio of the fluorosulfonate compound to the ionic liquid in the electrolyte additive is 1 (0.2-3.5). In some embodiments thereof, the electrolyte salt comprises a lithium salt or a sodium salt. In some embodiments, the solvent comprises at least one of a carbonate compound and a carboxylate compound. In some embodiments thereof, the lithium salt comprises at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium trifluoromethane sulfonate, lithium bis (trifluoromethane sulfonyl) imide, lithium bis (oxalato) borate, lithium difluorooxalato borate, lithium difluorophosphate, and lithium difluorodioxaato phosphate. In some embodiments, the sodium salt comprises at least one of sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium bis (trifluoromethylsulfonyl) imide, sodium dicarboxylate, sodium difluorophosphate, and sodium difluorodicarboxylate. In some embodiments thereof, the carbonate compound includes at least one of a cyclic carbonate and a chain carbonate. In some embodiments, the carboxylic acid ester compound includes at least one of a fluorinated carboxylic acid ester