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CN-122029641-A - Composition of main positive electrode layer

CN122029641ACN 122029641 ACN122029641 ACN 122029641ACN-122029641-A

Abstract

The present invention relates to a composition for preparing a main positive electrode layer, which comprises a polyacrylic acid-based binder having an extremely high molecular weight and carbon particles. The invention also relates to the use of the composition for producing a positive electrode, and to a positive electrode which can be used for producing a cell for a rechargeable battery.

Inventors

  • Greg Hader
  • Gary Robin
  • Jean-Marc Souault

Assignees

  • 可泰克斯公司

Dates

Publication Date
20260512
Application Date
20241018
Priority Date
20231020

Claims (13)

  1. 1. An aqueous composition C for preparing a positive electrode primer layer comprising: At least one material E comprising carbon particles, and At least one binder Q comprising at least one water-soluble polymer P having a molecular weight Mw greater than 300000g/mol as measured by SEC, said water-soluble polymer P being selected from: A polymer P1 in the presence of at least one initiator compound, prepared only by polymerization of, Amounts by weight relative to compound (a), compound (b) and compound (c): from 30 to 90 weight percent of at least one compound (a) independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; From 5% to 30% by weight of at least one compound (b) independently selected from the group consisting of styrene, C 1 to C 12 methacrylate, C 1 to C 12 acrylate, acrylamide, alkylacrylamide, N-methylolacrylamide, acrylonitrile, vinyllactam, ureido methacrylate, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof, and From 5 to 40 weight percent of at least one compound (c) independently selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid salt, ethoxymethacrylic acid sulfonic acid, sodium methacrylate sulfonic acid, styrene sulfonate salt, and combinations thereof; A polymer P2 in the presence of at least one initiator compound, prepared only by polymerization of, Amounts by weight relative to compound (a) and compound (b): From 35 to 90 weight percent of at least one compound (a) independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof, and From 10% to 65% by weight of at least one compound (b) independently selected from styrene, C 1 to C 12 methacrylate, C 1 to C 12 acrylate, acrylamide, alkylacrylamide, N-methylolacrylamide, acrylonitrile, vinyllactam, ureido methacrylate, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; A polymer P3 in the presence of at least one initiator compound, prepared only by polymerization of, Amounts by weight relative to compound (a) and compound (c): From 35 to 95 weight percent of at least one compound (a) independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof, and From 5 to 65 weight percent of at least one compound (c) independently selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid salt, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate salt, and combinations thereof; -a single polymer P4 prepared by polymerization of at least one compound (a) independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts and combinations thereof in the presence of at least one initiator compound; -combinations thereof.
  2. 2. Composition C according to claim 1, wherein: the polydispersity index PI of the polymer P, measured by SEC, is greater than 10, preferably greater than 15 or greater than 20, more preferably greater than 25 or greater than 30 or greater than 40, or wherein: The compound (a) is independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid salts, methacrylic acid salts and combinations thereof, preferably the compound (a) is acrylic acid or methacrylic acid, or The compound (b) is independently selected from styrene, t-butyl acrylamide, C 1 to C 12 methacrylate, C 1 to C 12 acrylate and combinations thereof, preferably C 1 to C 8 methacrylate, C 1 to C 8 acrylate and combinations thereof, preferably styrene, t-butyl acrylamide, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, more preferably methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, or The compound (c) is independently selected from 2-acrylamido-2-methylpropanesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid salt, or The polymer P4 is prepared using a single compound (a) or using two different compounds (a).
  3. 3. Composition C according to any one of claims 1 or 2, wherein: polymer P1 is prepared using, Amounts by weight relative to compound (a), compound (b) and compound (c): 50 to 90% by weight of a compound (a), 5 To 30% by weight of a compound (b), and 5 To 20% by weight of a compound (c), or Polymer P2 is prepared using, Amounts by weight relative to compound (a) and compound (b): 65 to 90% by weight of compound (a), and 10 To 35% by weight of a compound (b), or Polymer P3 is prepared using, Amounts by weight relative to compound (a) and compound (c): 65 to 95% by weight of compound (a), and 5 To 35% by weight of a compound (c), or wherein: The molecular weight Mw of the polymer P, measured by SEC, is from 300000g/mol to 10000000g/mol or from 350000g/mol to 10000000g/mol, preferably from 300000g/mol to 8000000g/mol or from 350000g/mol to 8000000g/mol, more preferably from 300000g/mol to 5000000g/mol or from 350000g/mol to 5000000g/mol or from 300000g/mol to 2000000g/mol or from 350000g/mol to 2000000g/mol, or The glass transition temperature Tg of the polymer P, calculated by the Flory-Fox equation, is from-10℃to 230℃or from 20℃to 230℃or a homopolymer in which the polymer P is a homopolymer having a Tg of greater than 0℃and preferably greater than 10℃or a copolymer in which the polymer P is a copolymer having a Tg of greater than 50℃and preferably greater than 100℃or The polymer P is completely acidic or partially acidic or not neutralized or partially not neutralized, preferably the polymer P is partially neutralized, preferably with at least one compound selected from LiOH, naOH, KOH, zn (OH) 2 、Mg(OH) 2 、Ca(OH) 2 , znO, mgO, caO, ammonium derivatives, ammonia, aqueous ammonia, an amino base such as triethanolamine, aminomethylpropanol or 2-amino-2-methylpropanol (AMP) and combinations thereof, more preferably with NaOH, ca (OH) 2 , caO.
  4. 4. A composition C according to any one of claims 1 to 3, wherein: The polymer P is prepared by polymerization in a liquid medium, wherein the initial concentration of monomers is from 5% to 20% by weight, preferably from 5% to 15% by weight or from 8% to 15% by weight, more preferably from 10% to 12% by weight, or wherein: the polymerization reaction is carried out in water alone or in combination with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and combinations thereof.
  5. 5. Composition C according to any one of claims 1 to 4, wherein: the binder Q comprises a single polymer P, or The binder Q comprises at least one polymer P and at least one liquid matrix, preferably water alone or in combination with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and combinations thereof, or wherein: The binder Q comprises: 5 to 20% by weight of polymer P and 95 to 80% by weight of liquid matrix, also preferably: 10 to 40% by weight of polymer P and 60 to 90% by weight of liquid matrix.
  6. 6. The composition C according to any one of claims 1 to 5, wherein material E is selected from carbon black, acetylene black, ketjen black, carbon fibers, carbon nanotubes, carbon nanofibers, hard carbon, and combinations thereof.
  7. 7. Composition C according to any one of claims 1 to 6, comprising, on a dry weight basis, relative to the total amount of binder Q and material E, by dry weight: from 0.5 to 70% of an adhesive Q, -30% To 99.5% of material E, preferably: from 0.5 to 60% of a binder Q, -40% To 99.5% of material E.
  8. 8. A process for the preparation of a water-soluble polymer P having a molecular weight Mw greater than 300000g/mol as measured by SEC, selected from the group consisting of: A polymer P1 in the presence of at least one initiator compound, prepared only by polymerization of, Amounts by weight relative to compound (a), compound (b) and compound (c): from 30 to 90 weight percent of at least one compound (a) independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; From 5% to 30% by weight of at least one compound (b) independently selected from the group consisting of styrene, C 1 to C 12 methacrylate, C 1 to C 12 acrylate, acrylamide, alkylacrylamide, N-methylolacrylamide, acrylonitrile, vinyllactam, ureido methacrylate, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof, and From 5 to 40 weight percent of at least one compound (c) independently selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid salt, ethoxymethacrylic acid sulfonic acid, sodium methacrylate sulfonic acid, styrene sulfonate salt, and combinations thereof; A polymer P2 in the presence of at least one initiator compound, prepared only by polymerization of, Amounts by weight relative to compound (a) and compound (b): From 35 to 90 weight percent of at least one compound (a) independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof, and From 10% to 65% by weight of at least one compound (b) independently selected from styrene, C 1 to C 12 methacrylate, C 1 to C 12 acrylate, acrylamide, alkylacrylamide, N-methylolacrylamide, acrylonitrile, vinyllactam, ureido methacrylate, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; A polymer P3 in the presence of at least one initiator compound, prepared only by polymerization of, Amounts by weight relative to compound (a) and compound (c): From 35 to 95 weight percent of at least one compound (a) independently selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof, and From 5 to 65 weight percent of at least one compound (c) independently selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid salt, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate salt, and combinations thereof; -a single polymer P4 prepared by polymerization of at least one compound (a) independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylic acid salts, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts and combinations thereof in the presence of at least one initiator compound; -combinations thereof.
  9. 9. The method of manufacturing according to claim 8, wherein: the polymerization is carried out in a liquid medium, in which the initial concentration of monomers is from 5% to 20% by weight, preferably from 5% to 15% by weight or from 8% to 15% by weight, more preferably from 10% to 12% by weight, or in which: the polymerization reaction is carried out in water alone or in combination with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and combinations thereof.
  10. 10. A method for preparing a positive electrode, comprising: -applying at least one primer layer of a composition C as defined in any one of claims 1 to 7 on a metal substrate comprising at least one metal selected from the group consisting of aluminum, nickel and combinations thereof; Drying the metal substrate carrying the primer layer, optionally followed by calendering, then Applying an electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound and at least one organic solvent, -Drying the metal substrate carrying the primer layer and the electroactive coating, followed by calendering.
  11. 11. The method according to claim 10, wherein: the substrate is a pure metal substrate or a composite substrate comprising at least one metal and at least one insulating substrate, or -The electroactive compound comprises at least one metal selected from the group consisting of lithium, iron, nickel, manganese, cobalt and combinations thereof, or The electroactive compound is in the form of a metal salt, preferably a multimetal salt, preferably the electroactive compound is selected from the group consisting of LiFePO 4 (LFP)、Li(Ni,Mn,Co)O 2 (NMC) and combinations thereof, or The adhesion compound of the electroactive compound is polyvinylidene fluoride (PVDF), preferably vinylidene fluoride homopolymer or copolymer of vinylidene fluoride with monomers selected from vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, 1, 2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro (alkyl vinyl) ethers such as perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE), perfluoro (1, 3-dioxole), perfluoro (2, 2-dimethyl-1, 3-dioxole) (PDD), perfluorobutyl ethylene (PFBE), trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutyl ethylene, pentafluoropropene, trifluorobromoethylene, vinyl chloride, trifluorochloropropene, or -The organic solvent is an aprotic polar solvent, preferably selected from pyrrolidone, N-methylpyrrolidone (NMP), alkyl carbonates and combinations thereof, or -The electroactive composition comprises carbon, preferably selected from carbon black, acetylene black, ketjen black, carbon fibers, carbon nanotubes, carbon nanofibers, hard carbon and combinations thereof.
  12. 12. A positive electrode comprising at least one metal substrate coated with at least one primer layer comprising a binder Q and at least one material E, the positive electrode being obtained according to the method of claim 10 or 11.
  13. 13. A method for improving adhesion of an electroactive composition to a metal positive electrode substrate comprising at least one metal selected from the group consisting of aluminum and nickel, the electroactive composition comprising at least one electroactive compound, at least one binding compound for the electroactive compound, and at least one organic solvent, the method comprising: -pre-application of at least one aqueous composition C for preparing a primer coating according to any one of claims 1 to 7 directly on a metal substrate, followed by drying and optionally calendering, followed by -Applying said electroactive composition to a substrate to be treated, -Drying the metal substrate carrying the primer layer and the electroactive coating, followed by calendering.

Description

Composition of main positive electrode layer The present invention relates to a composition for preparing a positive electrode undercoating layer, the composition comprising a polyacrylic binder having an extremely high molecular weight and carbon particles. The invention also relates to the use of the composition for producing a positive electrode, and to a positive electrode which can be used for producing a cell of a secondary battery. Known compositions for preparing positive electrodes generally comprise carbon and metal in particulate form combined with a binder composition. The binding composition is capable of fixing the particles to the metal substrate. Therefore, when positive electrodes are manufactured using these compositions, adhesion properties are decisive. The time and yield required to manufacture the positive electrode are also important factors. Therefore, it is important to improve the efficiency of the various reactions involved. As an electrochemically inactive ingredient during operation of the positive electrode, the binding compounds do not directly contribute to the capacity of the battery cell comprising the positive electrode, but their impact on the overall electrochemical performance is still substantial. These binding compounds should help form a stable network of active or conductive solid compounds present in the positive electrode. The binder compounds used in the preparation of the positive electrode should also be able to improve thermal, chemical and electrochemical stability and tensile strength, in particular by good adhesion and good cohesion, and a degree of flexibility. In addition, the compatibility of the various components of the compositions used to prepare the positive electrode with the battery is also an important factor to be considered in preparing these compositions and in preparing the positive electrode using these compositions. In particular, compatibility with the electrolyte in the battery, especially insolubility or low solubility, is an essential property. It is desirable that the composition used to prepare the positive electrode be easy to apply uniformly to obtain a uniform coating and limit or avoid defects on the electrode surface, thereby forming a uniform and particularly effective conductive coating. The surface leveling, reconstruction and flow behavior of the composition used to prepare the positive electrode must be well controlled. The composition used to prepare the positive electrode must also be stable and homogeneous during its preparation, storage or application. Thus, sedimentation, formation of clusters or aggregates, and separation of components must be limited or avoided. In general, in the preparation of the positive electrode, improvement in the adhesion of the active element should be always sought. Therefore, it is necessary to improve the adhesion of the coating of different composition deposited on the metal substrate. In particular, when an undercoat layer containing carbon is deposited on a metal substrate, it is important to improve its adhesion. The properties of the primer coating compositions are particularly important because of their direct contact with the metal positive electrode substrate and with the bonding composition of the electroactive compound. Document CN 115881966 discloses a composition for the preparation of a positive electrode, which combines two polymers modified by conductive chemical groups, in particular by polyaniline groups. Document EP 4095213 describes an electrode bonding composition comprising a copolymer of N-vinylpyrrolidone, methacrylonitrile, vinyl acetate or acrylic acid. Document WO 2014024937 describes a composition for the preparation of negative electrodes comprising fluorinated copolymers having a low molecular weight. Document WO 2015008626 describes an electrode adhesive composition comprising a copolymer with extremely high molecular weight prepared essentially from anionic monomers. Document US 20170018770 discloses a method for preparing a positive electrode using a binding composition combining at least two polyacrylic acids having very different molecular weights. In addition to the composition for preparing a positive electrode comprising a PVDF binder in NMP, document KR 20190143256 describes a silicon negative electrode composition comprising two polyacrylic acid binders having different molecular weights. Document WO 24028544, which is published after the present application has been filed, discloses a composition for preparing a negative electrode using an acrylic-acrylate copolymer for carbon dispersion. The compositions commonly used in the art for preparing the primer layer for the positive electrode are not always satisfactory. Thus, there is a need for a composition for use in preparing a positive electrode primer layer that provides a solution to all or part of the problems of the compositions of the prior art. Accordingly, the present invention provides an aqu