CN-122025538-A - Positive electrode plate, preparation method thereof, battery and electric equipment

Abstract

The application discloses a positive electrode plate, a preparation method thereof, a battery and electric equipment, wherein the positive electrode plate is provided with a positive electrode current collector, a positive electrode active material layer is formed on at least one side of the positive electrode current collector, the positive electrode active material layer comprises an additive, the additive comprises at least one of elemental sulfur, sulfide, elemental selenium, selenide, elemental phosphorus, phosphide, elemental tellurium, elemental iodine or elemental boron, and the average particle size of the additive is more than or equal to 2 mu m. Therefore, the additive is passivated, the reactivity of the additive is reduced, the solubility of the additive in electrolyte is reduced, the consumption of active ions by oxidation products of the additive is reduced, and the cycle life of the battery is prolonged.

Inventors

• WU KAI
• LIU HUANJI
• LIN KUI
• XIE HAOTIAN
• CHEN XIAO
• SUN XIN
• YE YONGHUANG

Assignees

• 宁德时代新能源科技股份有限公司

Dates

Publication Date

20260512

Application Date

20231108

Claims (15)

1. 1. A positive electrode sheet, characterized by comprising: A positive electrode current collector; The positive electrode active material layer is formed on at least one side of the positive electrode current collector, the positive electrode active material layer comprises an additive, the additive comprises at least one of elemental sulfur, sulfide, elemental selenium, selenide, elemental phosphorus, phosphide, elemental tellurium, elemental iodine or elemental boron, and the average grain size of the additive is larger than or equal to 2 mu m.
2. 2. The positive electrode sheet according to claim 1, wherein the additive has an average particle diameter of 3 μm to 30 μm, optionally the additive has an average particle diameter of 6 μm to 20 μm.
3. 3. The positive electrode sheet according to claim 1 or 2, characterized in that at least one of the following conditions is satisfied: (1) The sulfide comprises at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide or nickel sulfide; (2) The phosphide comprises at least one of lithium phosphide or sodium phosphide; (3) The selenide comprises at least one of lithium selenide or sodium selenide.
4. 4. A positive electrode sheet according to any one of claims 1 to 3, wherein the mass ratio of the additive is 0.1% to 0.5%, optionally 0.1% to 0.3%, based on the total mass of the positive electrode active material layer.
5. 5. The positive electrode sheet according to any one of claims 1 to 4, wherein the positive electrode active material layer comprises a positive electrode active material, and a ratio of a volume average particle diameter D v of the positive electrode active material to an average particle diameter of the additive is 1 or less.
6. 6. The positive electrode sheet according to any one of claims 1 to 5, wherein at least part of the surface of the additive is formed with a coating layer.
7. 7. The positive electrode sheet according to claim 6, wherein the ratio of the mass of the coating layer to the mass of the additive is 0.003-0.02, optionally 0.008-0.02, based on the total mass of the additive.
8. 8. The positive electrode sheet according to claim 6 or 7, wherein the coating layer comprises at least one of polyvinylidene fluoride, a vinylidene fluoride-hexafluoropropylene copolymer, aluminum oxide, titanium oxide, zirconium oxide, aluminum fluoride, titanium fluoride, sodium alginate, styrene-butadiene rubber, polyacrylic acid and its derivatives, polytetrafluoroethylene, polymethyl methacrylate, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyvinyl alcohol, or polyethylene glycol.
9. 9. The positive electrode sheet according to any one of claims 1 to 8, wherein a ratio of a thickness of the positive electrode active material layer to an average particle diameter of the additive is 2 or more.
10. 10. A preparation method of the positive electrode plate is characterized by comprising the step of forming a positive electrode active material layer on at least one side of a positive electrode current collector, wherein the positive electrode active material layer comprises an additive, the additive comprises at least one of elemental sulfur, sulfide, elemental selenium, selenide, elemental phosphorus, phosphide, elemental tellurium, elemental iodine or elemental boron, and the average particle size of the additive is more than or equal to 2 mu m.
11. 11. The method of claim 10, further comprising forming a coating on at least a portion of a surface of the additive.
12. 12. A battery comprising the positive electrode sheet of any one of claims 1-9 or the positive electrode sheet prepared by the method of claim 10 or 11.
13. 13. The battery of claim 12, further comprising an electrolyte comprising a cyclic solvent.
14. 14. The battery of claim 13, wherein the cyclic solvent comprises at least one of vinylene carbonate, butylene carbonate, sulfolane, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, or 1, 4-butyrolactone.
15. 15. A powered device comprising a battery as claimed in any one of claims 12-14.

Description

Positive electrode plate, preparation method thereof, battery and electric equipment The application relates to a positive pole piece and a preparation method thereof, and a divisional application of a battery and electric equipment, which are disclosed by the application, wherein the application number is 202311481751.5, the application date is 2023, 11 and 08. Technical Field The application relates to the field of batteries, in particular to a positive pole piece, a preparation method thereof, a battery and electric equipment. Background The battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, as well as a plurality of fields such as military equipment, aerospace, and the like. However, the SEI film (solid electrolyte interface) on the surface of the negative electrode plate of the existing battery has lower toughness, and can be continuously broken and recombined in the circulation process, so that the consumption of active ions is increased, and the cycle life of the battery is reduced. Disclosure of Invention In view of the technical problems in the background technology, the application provides the positive electrode plate, which reduces the consumption of active ions and improves the cycle life of a battery. The first aspect of the application provides a positive electrode sheet, which comprises a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer is formed on at least one side of the positive electrode current collector, the positive electrode active material layer comprises an additive, the additive comprises at least one of elemental sulfur, sulfide, elemental selenium, selenide, elemental phosphorus, phosphide, elemental tellurium, elemental iodine or elemental boron, and the average particle size of the additive is more than or equal to 2 mu m. The positive electrode plate comprises an additive, wherein the additive can form an organic chain segment with an annular solvent in electrolyte, the organic chain segment can be diffused to a negative electrode to combine with active ions to form an SEI film, the additive is dissolved in the electrolyte and reduced after migrating to the negative electrode, a reduction product reacts with the organic solvent in the electrolyte to generate a PEO-like polymer, and the PEO-like polymer combines with the active ions to form the SEI film. Thus, the toughness of the formed SEI film can be improved, thereby reducing the direct current internal resistance (DCR) of the battery and improving the cycle life of the battery. By making the average particle diameter of the additive within the above range, the specific surface area of the additive can be reduced, the reactive sites on the surface of the additive can be reduced, the additive can be passivated, the solubility in the electrolyte can be reduced, the probability of further oxidizing the additive can be reduced, the reaction of the oxidation product of the additive and the active ions can be reduced, the consumption of the active ions by the oxidation product of the additive can be reduced, and the cycle life of the battery can be prolonged. According to some embodiments of the application, the additive has an average particle size of 3 μm to 30 μm. Therefore, the additive is further passivated, the solubility of the additive in the electrolyte is reduced, the consumption of active ions by oxidation products of the additive is reduced, and the cycle life of the battery is prolonged. According to some embodiments of the application, the additive has an average particle size of 6 μm to 20 μm. Therefore, the additive is further passivated, the solubility of the additive in the electrolyte is reduced, the consumption of active ions by oxidation products of the additive is reduced, and the cycle life of the battery is prolonged. According to some embodiments of the application, the sulfide includes at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide, or nickel sulfide. According to some embodiments of the application, the phosphide comprises at least one of lithium phosphide or sodium phosphide. According to some embodiments of the application, the selenide comprises at least one of lithium selenide or sodium selenide. Thus, the above-mentioned kinds of sulfides, phosphides, and selenides can participate in the formation of SEI films, and the toughness of SEI films is improved, and the average particle size of the above-mentioned kinds of sulfides, phosphides, and selenides is made to be 2 μm or more, so that the consumption of active ions by oxidation products of the above-mentioned kinds of additives is reduced, and the cycle life of the battery is improved. According to some embod