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CN-122025832-A - Lithium-sulfur battery, electrolyte and electric equipment

CN122025832ACN 122025832 ACN122025832 ACN 122025832ACN-122025832-A

Abstract

The application discloses a lithium sulfur battery, an electrolyte and electric equipment, which belong to the field of secondary batteries, wherein the lithium sulfur battery comprises a positive electrode plate, the electrolyte and a negative electrode plate, the positive electrode plate comprises a positive electrode active material, the positive electrode active material comprises sulfur and conductive carbon containing doping elements, the doping elements comprise one or more of N element, B element or P element, and the electrolyte comprises lithium salt, a solvent and a diluent. The lithium sulfur battery has excellent specific capacity and cycle performance.

Inventors

  • LIANG ZIBIN
  • XU YIDA
  • ZHANG XINXIN
  • GUO BINGKUN

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (16)

  1. 1. A lithium sulfur battery is characterized by comprising a positive electrode plate, an electrolyte and a negative electrode plate, The positive electrode plate comprises a positive electrode active material, wherein the positive electrode active material comprises sulfur and conductive carbon containing doping elements, and the doping elements comprise one or more of N element, B element or P element; the electrolyte includes a lithium salt, a solvent, and a diluent.
  2. 2. The lithium sulfur battery of claim 1 wherein the doping element comprises at least two of an N element, a B element, or a P element.
  3. 3. The lithium sulfur battery according to claim 1 or 2, wherein the mass ratio of the doping element is 0.3% to 3% based on the total mass of the conductive carbon containing the doping element.
  4. 4. A lithium sulfur battery according to any of claims 1-3 wherein the mass ratio of the conductive carbon containing doping element to the sulfur is (1:9) - (5:5).
  5. 5. The lithium sulfur battery according to any one of claims 1 to 4, wherein an amount concentration of a substance of the lithium salt in the lithium salt and the solvent is 0.1mol/L to 5mol/L.
  6. 6. The lithium sulfur battery of any of claims 1-5 wherein the lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, or lithium tetrafluorooxalato phosphate.
  7. 7. The lithium sulfur battery of any of claims 1-6 wherein the solvent comprises one or more of 1, 2-dimethoxypropane, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, 1, 3-dioxolane, or dimethyl ether.
  8. 8. The lithium sulfur battery of any of claims 1-7 wherein the diluent comprises a fluoroether-type diluent.
  9. 9. The lithium sulfur battery as in claim 8, wherein, the fluoroether diluent comprises 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether one or more of bis (2, 2-trifluoroethyl) ether or 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether.
  10. 10. The lithium sulfur battery according to any of claims 1 to 9 wherein the sum of the volumes of solvent and lithium salt is the volume of the diluent = (1:99) - (20:80).
  11. 11. The lithium sulfur battery of any of claims 1-10 wherein the positive electrode sheet comprises a current collector and a positive electrode slurry disposed on at least one side of the current collector, the positive electrode slurry comprising the positive electrode active material and the electrolyte.
  12. 12. The lithium-sulfur battery according to claim 11, wherein the mass ratio of the components in the positive electrode slurry is positive electrode active material: electrolyte: conductive agent= (10-50): (50-90): (0.5-10).
  13. 13. A method for preparing a lithium sulfur battery, comprising: assembling the positive electrode plate, the electrolyte and the negative electrode plate to obtain the lithium sulfur battery, The positive electrode plate comprises a positive electrode active material, wherein the positive electrode active material comprises sulfur and conductive carbon containing doping elements, and the doping elements comprise at least one of N element, B element or P element; the electrolyte includes a lithium salt, a solvent, and a diluent.
  14. 14. The method according to claim 13, wherein the positive electrode active material is prepared by: Mixing conductive carbon with at least one of an N source, a B source or a P source, and calcining under the protection of inert gas to obtain conductive carbon containing doping elements; and mixing the conductive carbon containing the doping element with sulfur, and heating under the protection of inert gas to obtain the anode active material.
  15. 15. The method of claim 14, wherein at least one of the following conditions is satisfied: The calcination temperature is 700-1200 ℃; the heating temperature is 120-200 ℃.
  16. 16. A powered device comprising a lithium sulfur battery according to any one of claims 1-12.

Description

Lithium-sulfur battery, electrolyte and electric equipment Technical Field The application belongs to the field of secondary batteries, and particularly relates to a lithium-sulfur battery, an electrolyte and electric equipment. Background The secondary battery is widely applied to energy storage power supply systems such as hydraulic power, firepower, wind power, solar power stations and the like, and a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. The lithium-sulfur battery is a lithium battery with sulfur element as a battery anode and metal lithium as a cathode. The elementary sulfur has the characteristics of abundant reserves in the earth, low price, environmental friendliness and the like. The lithium sulfur battery using sulfur as the positive electrode material has higher material theoretical specific capacity and battery theoretical specific energy which respectively reach 1675mAh/g and 2600Wh/kg, however, the intermediate product lithium polysulfide of the lithium sulfur battery is easy to dissolve in electrolyte and can shuttle to the negative electrode metal lithium side, and side reaction occurs with the metal lithium to consume the metal lithium and form non-conductive lithium sulfide to cover the surface of the metal lithium, so that the capacity and the cycle performance are reduced. Disclosure of Invention In view of the technical problems in the background art, the application provides a lithium-sulfur battery, which aims to improve the capacity and the cycle performance of the lithium-sulfur battery. In order to achieve the above object, a first aspect of the present application provides a lithium-sulfur battery comprising a positive electrode sheet including a positive electrode active material including sulfur and conductive carbon containing a doping element including at least one of N element, B element, or P element, an electrolyte including a lithium salt, a solvent, and a diluent, and a negative electrode sheet. The lithium sulfur battery at least has the following beneficial effects that the diluent is used in the electrolyte, and the capacity and the cycle performance of the lithium sulfur battery can be improved by matching the diluent with the conductive carbon containing the doping element. In some embodiments, the doping element includes at least two of an N element, a B element, or a P element. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the mass fraction of the doping element is 0.3% -3% based on the total mass of the doping element-containing conductive carbon. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the mass ratio of the conductive carbon containing the doping element to the sulfur is (1:9) - (5:5). Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the lithium salt and the solvent have an amount concentration of the substance of the lithium salt of 0.1mol/L to 5mol/L. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, or lithium tetrafluorooxalato phosphate. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the solvent comprises one or more of 1, 2-dimethoxypropane, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, 1, 3-dioxapentacyclic or dimethyl ether. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the diluent comprises a fluoroether-based diluent. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments of the present invention, in some embodiments, the fluoroether diluent comprises 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether one or more of bis (2, 2-trifluoroethyl) ether or 1, 2-tetrafluoroethyl 2, 3-tetrafluoropropyl ether. Thus, the capacity and cycle performance of the lithium-sulfur battery can be improved. In some embodiments, the sum of the