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CN-122029643-A - Electrode-forming composition, additive, and gelation inhibitor

CN122029643ACN 122029643 ACN122029643 ACN 122029643ACN-122029643-A

Abstract

An electrode-forming composition comprising a compound having a ring structure and an unsaturated bond, a positive electrode active material, a binder, and a solvent, the compound having a dissociable proton within a molecule, the compound having a proton dissociation energy of less than 1504.7 (kJ/mol), and the compound having a bond dissociation energy of less than 452.61 (kJ/mol).

Inventors

  • HATANAKA TATSUY
  • KUBO TOMOKO
  • ASAKA Yukio

Assignees

  • 日产化学株式会社

Dates

Publication Date
20260512
Application Date
20241105
Priority Date
20231201

Claims (20)

  1. 1. A composition for forming an electrode, which comprises a compound having a ring structure and an unsaturated bond, a positive electrode active material, a binder, and a solvent, The compound has dissociative protons within the molecule, The proton dissociation energy of the compound is less than 1504.7kJ/mol, The bond dissociation energy of the compound is less than 452.61kJ/mol.
  2. 2. The composition for forming an electrode according to claim 1, wherein, The positive electrode active material includes a first positive electrode active material of a polycrystal and a second positive electrode active material of a single crystal.
  3. 3. The composition for forming an electrode according to claim 2, wherein, The first positive electrode active material is lithium-containing transition metal oxide particles having a layered rock salt structure, and the lithium-containing transition metal oxide particles have a crystallite diameter of 20nm or more and less than 500nm as determined by the scherrer formula, based on a diffraction peak of a (104) plane obtained from an X-ray diffraction pattern using a cukα radiation source.
  4. 4. The composition for forming an electrode according to claim 2, wherein, The second positive electrode active material is lithium-containing transition metal oxide particles having a layered rock salt structure, and the lithium-containing transition metal oxide particles have a crystallite diameter of 50nm or more and less than 800nm as determined by the scherrer formula, based on a diffraction peak of a (104) plane obtained from an X-ray diffraction pattern using a cukα radiation source.
  5. 5. The electrode-forming composition according to claim 3, wherein, The lithium-containing transition metal oxide particles having a layered rock salt structure in the first positive electrode active material are crystalline metal oxide particles represented by the general formula Li a Ni （1－x－y） Co x M 1 y M 2 z O 2 , wherein M 1 represents at least one selected from the group consisting of Mn and Al, M 2 represents at least one selected from the group consisting of Zr, ti, mg, B, W and V, and 1.00 a≤ 1.50,0.00 x≤ 0.50,0.00 y≤ 0.50,0.000 z≤0.020.
  6. 6. The composition for forming an electrode according to claim 4, wherein, The lithium-containing transition metal oxide particles having a layered rock salt structure in the second positive electrode active material are crystalline metal oxide particles represented by the general formula Li a Ni （1－x－y） Co x M 1 y M 2 z O 2 , wherein M 1 represents at least one selected from the group consisting of Mn and Al, M 2 represents at least one selected from the group consisting of Zr, ti, mg, B, W and V, and 1.00 a≤ 1.50,0.00 x≤ 0.50,0.00 y≤ 0.50,0.000 z≤0.020.
  7. 7. The composition for forming an electrode according to claim 1, wherein, The ring structure is an aromatic ring.
  8. 8. The composition for forming an electrode according to claim 1, wherein, The compounds have heteroatoms.
  9. 9. The composition for forming an electrode according to claim 1, wherein, The positive electrode active material contains a metal oxide containing Ni.
  10. 10. The composition for forming an electrode according to claim 1, wherein, The positive electrode active material contains Ni, and the Ni content in the positive electrode active material is 30 mass% or more and 61 mass% or less.
  11. 11. The composition for forming an electrode according to claim 1, wherein, The solvent is an aprotic solvent.
  12. 12. The composition for forming an electrode according to claim 1, wherein, The adhesive is a fluorine-based adhesive.
  13. 13. The composition for forming an electrode according to claim 1, wherein, The electrode-forming composition further comprises a conductive auxiliary agent.
  14. 14. An electrode layer obtained from the composition for electrode formation according to any one of claims 1 to 13.
  15. 15. A secondary battery provided with the electrode layer according to claim 14.
  16. 16. A method for producing the electrode-forming composition according to any one of claims 1 to 13, the method for producing the electrode-forming composition comprises: mixing the compound, the binder, the solvent, the first positive electrode active material of the polycrystal, and the second positive electrode active material of the single crystal.
  17. 17. The method for producing an electrode-forming composition according to claim 16, wherein, The mass ratio of the first positive electrode active material to the second positive electrode active material in the electrode-forming composition, i.e., the first positive electrode active material to the second positive electrode active material, is 2: 8~8:2.
  18. 18. An additive which is an additive of an electrode-forming composition comprising a first positive electrode active material of a polycrystal, a second positive electrode active material of a single crystal, a binder and a solvent, The additive has dissociative protons in molecules, the proton dissociation energy is less than 1504.7kJ/mol, and the bond dissociation energy is less than 452.61kJ/mol.
  19. 19. A gelation inhibitor which is a gelation inhibitor of an electrode-forming composition comprising a first positive electrode active material of a polycrystal, a second positive electrode active material of a single crystal, a binder and a solvent, The gelation inhibitor has dissociative protons in the molecule, the proton dissociation energy is less than 1504.7kJ/mol, and the bond dissociation energy is less than 452.61kJ/mol.
  20. 20. A method for inhibiting gelation, which comprises a step of inhibiting gelation of an electrode-forming composition comprising a first positive electrode active material of a polycrystal, a second positive electrode active material of a single crystal, a binder and a solvent, The electrode-forming composition is in a state of containing a compound having a dissociative proton in a molecule, a proton dissociation energy of less than 1504.7kJ/mol, and a bond dissociation energy of less than 452.61kJ/mol.

Description

Electrode-forming composition, additive, and gelation inhibitor Technical Field The present invention relates to an electrode forming composition, an additive, and a gelation inhibitor. The present invention also relates to an electrode layer, a secondary battery, a method for producing the electrode forming composition, and a method for suppressing gelation of the electrode forming composition. Background The lithium ion secondary battery has a high energy density per unit weight and unit volume, and thus contributes to downsizing and weight saving of electronic devices mounted thereon. In recent years, as a countermeasure against zero emission for automobiles, popularization of electric automobiles has been accelerated, and further reduction in resistance, prolongation of life, increase in capacity, safety, and reduction in cost have been sought. The lithium ion secondary battery generally has a structure in which a three-layer structure of a positive electrode, a separator, and a negative electrode contains an electrolyte. The positive electrode and the negative electrode are produced by, for example, mixing an active material, a conductive material, and a binder, and applying the electrode slurry obtained by mixing to a current collector. Currently, as a method for producing a negative electrode, a method for producing a positive electrode by applying a negative electrode slurry to a copper foil serving as a current collector and drying the copper foil, and a method for producing a positive electrode by producing a positive electrode slurry using an organic solvent such as N-methyl-2-pyrrolidone as a solvent and applying the obtained positive electrode slurry to an aluminum foil serving as a current collector are mainly used. As a positive electrode active material of a lithium ion secondary battery, an inorganic compound such as a transition metal oxide or a transition metal chalcogenide containing an alkali metal is known as a material capable of obtaining a battery voltage of about 4V. Among them, in order to obtain a lithium ion secondary battery having a high capacity, a large amount of a positive electrode active material having high alkalinity, which contains nickel and manganese, is used. For example, a high-nickel positive electrode active material represented by Li xNiO2 is a positive electrode material having a high discharge capacity and attractive properties, but has an alkaline component such as LiOH or Li 2O、LiHCO3、Li2CO3 formed by a proton exchange reaction between a residue of a raw material and moisture and a reaction with moisture and carbon dioxide gas in the air. When such a positive electrode active material is used, there is a problem in that the electrode slurry thickens or gels, and thus fluidity is gradually lost. If the fluidity of the electrode paste is lost, it is difficult to obtain a uniform coating thickness, and if necessary, coating cannot be performed, resulting in waste of material. The main reason for this is that in the step of producing the positive electrode, the alkaline component present on the surface of the positive electrode active material promotes the dehydrofluorination reaction of a fluorine-based binder represented by polyvinylidene fluoride (PVdF) having a vinylidene fluoride structure, which is used as a binder, in the presence of a small amount of moisture. The alkaline component corrodes aluminum foil, which is usually used as a collector foil of the positive electrode, thereby increasing the resistance of the battery. In addition, the alkaline component may react with the electrolyte in the battery, thereby increasing the resistance of the battery and possibly deteriorating the life. The thickening and gelation described above can be suppressed by controlling the amount of water by operating the raw material and the electrode slurry in a dry environment, but a large-scale facility is required in a series of mass production steps from the preparation of the electrode slurry to the production of the battery, and the cost increase and the increase in environmental load due to the use of a large amount of electricity become problems. In order to solve this problem, for example, patent document 1 discloses a technique of suppressing gelation of an electrode slurry by performing preparation of the electrode slurry (positive electrode material slurry) so as not to show strong basicity even when dispersed in water. However, in the method described in patent document 1, not only strict pH control but also treatment is required to prepare an electrode slurry so as not to show strong basicity, and it is necessary to temporarily disperse a positive electrode active material in water, filter and take out the positive electrode active material from the dispersion, and then dry it. As a result, the work is complicated and the yield is lowered. Further, the treatment as described above may also cause a decrease in the performance of the positive electrode active ma