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EP-4740248-A1 - BINDER IN POWDER FORM FOR THE PREPARATION OF AN ELECTRODE IN A SOLVENT-FREE PROCESS

EP4740248A1EP 4740248 A1EP4740248 A1EP 4740248A1EP-4740248-A1

Abstract

The present invention relates to an electrode binder comprising a polymer P1 and a polymer P2 that form an interpenetrating or semi-interpenetrating polymer network.

Inventors

  • MARCHAL, Lauréline
  • Bizet, Stéphane
  • DEVISME, SAMUEL

Assignees

  • ARKEMA France

Dates

Publication Date
20260513
Application Date
20240705

Claims (16)

  1. 1. Powder binder comprising a polymer PI comprising monomeric units derived from a fluorinated monomer and a polymer P2 comprising at least one monomeric unit derived from a monomer M2 of formula R 1 R 2 C=C(R 3 )C(O)R in which the substituents R 1 , R 2 and R 3 are independently of each other selected from the group consisting of H and C1-C5 alkyl; R is selected from the group consisting of -NHC(CH3) 2 CH 2 C(O)CH3 or -OR' with R' selected from the group consisting of H and C1-C5 alkyl optionally substituted by one or more -OH, CO2H, SO3H, PO3H groups or a five- or six-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; said polymer PI and said polymer P2 form an interpenetrating polymer network or a semi-interpenetrating polymer network; characterized in that said binder has a particle size distribution Dv50 less than or equal to 25pm.
  2. 2. Binder according to the preceding claim, characterized in that it has a particle size distribution Dv50 less than or equal to 10 pm.
  3. 3. Binder according to any one of the preceding claims, characterized in that it has a particle size distribution Dv90 less than or equal to 100 pm, preferably less than or equal to 25 pm.
  4. 4. Binder according to any one of the preceding claims, characterized in that said polymer PI is a homopolymer of vinylidene fluoride or a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units of a monomer Ml selected from the group consisting of vinyl fluoride; trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); 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); the product of formula CF2=CFOCF 2 CF(CF3)OCF2CF 2 X in which X is SO 2 F, CO 2 H, CH 2 OH, CH 2 OCN or Tl CH2OPO3H; the product of formula CF2=CFOCF2CF2SC>2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R 1 CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R 2 OCF=CH2 in which R 2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof.
  5. 5. Binder according to any one of the preceding claims, characterized in that the polymer PI is a homopolymer of vinylidene fluoride or a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from a monomer Ml selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene or a mixture thereof.
  6. 6. Binder according to any one of the preceding claims, characterized in that said PI polymer comprises monomer units carrying at least one of the functions selected from the group consisting of carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy groups such as glycidyl, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, phosphonic, or a mixture thereof.
  7. 7. Binder according to any one of the preceding claims, characterized in that said monomer M2 is of formula R 1 R 2 C=C(R 3 )C(O)OR' in which the substituents R 1 , R 2 and R 3 are independently of each other selected from the group consisting of H and C1-C5 alkyl; R' selected from the group consisting of H and C1-C5 alkyl optionally substituted by one or more group(s) -OH, CO2H, SO3H, PO3H.
  8. 8. Binder according to any one of the preceding claims, characterized in that said polymer P2 comprises: from 50 to 100% by weight of monomeric units derived from at least one monomer of formula R 1 R 2 C=C(R 3 )C(O)OR' in which the substituents R 1 , R 2 and R 3 are independently of each other selected from the group consisting of H and C1-C5 alkyl; R' selected from the group consisting of Ci-Cis alkyl; from 0 to 30% by weight of monomeric units derived from at least one monomer of formula R 1 R 2 C=C(R 3 )C(O)OR' in which the substituents R 1 , R 2 and R 3 are independently of each other selected from the group consisting of H and C1-C5 alkyl; R' selected from the group consisting of H and Ci-Cis alkyl bearing one or more functional groups selected from the group consisting of CO2H, PO3H, SO3H; from 0 to 20% by weight of monomeric units derived from at least one monomer of formula R 1 R 2 C=C(R 3 )C(O)OR' in which the substituents R 1 , R 2 and R 3 are independently of each other selected from the group consisting of H and C1-C5 alkyl; R' selected from the group consisting of Ci-Cis alkyl bearing one or more -OH functional groups.
  9. 9. Electrode composition in powder form for the preparation of a dry coated electrode comprising said binder according to any one of the preceding claims, an active material and optionally a conductive agent, an additive or a mixture of both; characterized in that said composition has a tapped density of at least 70% of the tapped density of said active material measured according to ISO 1068:1975.
  10. 10. An electrode composition according to the preceding claim, having the following mass composition: a. 50% to 99.9% of active material, preferably 50% to 99%, b. 0.1% to 25% of binder according to any one of the preceding claims 1 to 8, preferably 0.5% to 25%, c. 0% to 25% of conductive agent, preferably 0.5% to 25%, d. 0% to 5% of at least one additive selected from the group consisting of a plasticizer, an ionic liquid, a dispersing agent for conductive additive, and a flow aid; the sum of all these percentages being 100%.
  11. 11. Electrode composition according to any one of the preceding claims 9 or 10 characterized in that it comprises a conductive agent being composed of one or more materials selected from the group consisting of carbon black, graphite, carbon fibers, carbon nanotubes, carbon nanofibers, metal powders such as a SUS powder and an aluminum powder, or their mixtures.
  12. 12. An electrode composition according to any one of the preceding claims 9 to 11 wherein said active material is selected from the group consisting of: LiCoCh, Li(Ni, Co, AI)O 2 , Li(i + X )Ni a MnbCOc (x represents a real number of 0 or more, a = 0.8, 0.6, 0.5, or 1/3, b = 0.1, 0.2, 0.3, or 1/3, c = 0.1, 0.2, or 1/3), LiNiO 2 , LiMn 2 O 4 , LiCoMnO 4 , LisNiMnsOs, Li3Fe 2 (PO 4 )3, Li3V 2 (PO 4 )3, a Li Mn spinel substituted by a different element having a composition represented by Lii +x Mn 2 .x-yMyO 4 , M representing at least one metal selected from Al, Mg, Co, Fe, Ni, and Zn, x and y independently representing a real number between 0 and 2, lithium titanate Li x TiO y - x and y independently representing a real number between 0 and 2, and a lithium metal phosphate having a composition represented by LiMPO 4 , M representing Fe, Mn, Co, or Ni.
  13. 13. An electrode composition according to any one of the preceding claims 9 to 12 wherein said active material is selected from the group consisting of a lithium alloy, lithium metal, a metal oxide, a carbon material such as graphite or hard carbon, silicon, silicone, a silicon alloy and Li 4 Ti 5 0i 2 .
  14. 14. Dry coated electrode comprising a current collector, preferably made of copper, and a layer consisting of the electrode composition according to any one of the preceding claims 9 to 13, preferably said layer is in contact with the current collector.
  15. 15. Process for preparing a dry coated electrode according to the preceding claim, characterized in that it comprises the steps of: - mixture of said active material in powder form, of said binder according to any one of claims 1 to 8, and optionally of the conductive agent in the form of powder, powder additive or both to form said electrode composition according to any one of preceding claims 9 to 13; - depositing said electrode composition on said current collector to form an electrode, and - Optionally, consolidating said electrode by thermomechanical treatment.
  16. 16. A Li-ion battery comprising a positive electrode, a negative electrode and a separator, at least one electrode being a dry-coated electrode according to claim 14.

Description

DESCRIPTION TITLE: Powder binder for the preparation of an electrode in a solvent-free process Technical field The present invention relates generally to the field of electrical energy storage in Li-ion type lithium storage batteries. More specifically, the invention relates to a binder for a dry-coated electrode for a Li-ion battery. Another subject of the invention is a method for preparing an electrode using said binder. The invention also relates to lithium-ion batteries manufactured by incorporating said electrode. Technological background of the invention An elementary cell of a Li-ion storage battery or a lithium battery comprises an anode (on discharge), and a cathode (also on discharge) generally composed of a lithium insertion compound of the metal oxide type, such as LiM^C, LiCoCh or LiN iÜ2, between which is inserted an electrolyte which conducts the lithium ions. Rechargeable or secondary cells are more advantageous than primary (non-rechargeable) cells since the associated chemical reactions that take place at the positive and negative electrodes of the battery are reversible. Secondary cell electrodes can be regenerated multiple times by applying an electrical charge. Many advanced electrode systems have been developed to store an electrical charge. In parallel, much effort has been devoted to the development of electrolytes capable of improving the capabilities of electrochemical cells. For their part, the electrodes generally comprise at least one current collector on which is deposited, in the form of a film, a composite material consisting of a material called active material because it has an electrochemical activity with respect to lithium, a polymer which acts as a binder, plus one or more electronically conductive additives which are generally carbon black or acetylene black, and possibly a surfactant. Binders are classified as so-called inactive components since they do not directly contribute to the cell capacity. However, their key role in electrode processing and their considerable influence on electrochemical performance of electrodes have been widely described. The main relevant physical and chemical properties of binders are thermal stability, chemical and electrochemical stability, tensile strength (strong adhesion and cohesion), and flexibility. The main objective of using a binder is to form stable networks of the solid components of the electrodes, i.e., active materials and conductive agents (cohesion). In addition, the binder must ensure the close contact of the composite electrode to the current collector (adhesion). The current manufacturing process for lithium-ion battery electrodes, the "slurry" process, uses a solvent. This process consists of preparing an ink by mixing an active material, a conductive filler and a polymer binder in a solvent. This ink is then deposited on a current collector and the solvent is evaporated. A large part of the energy consumed by this process comes from the solvent evaporation step. A strong trend in the field of lithium-ion batteries is to reduce manufacturing costs, which involves limiting the costs related to energy consumption for manufacturing. Compared with the conventional wet-suspension electrode manufacturing process, dry (solvent-free) manufacturing processes are simpler; these processes eliminate volatile organic compound emissions and offer the possibility to manufacture electrodes with larger thicknesses (> 120 pm), with a higher energy density of the final energy storage device. The change in production technology will have little impact on the active material of the electrodes, however, the polymer additives responsible for the mechanical integrity of the electrodes must be adapted to the new manufacturing conditions. The adhesion of the coating to the current collector obtained with a solvent-free process is often lower than that obtained with a slurry process. To improve the adhesion to the current collector, one solution is to use a current collector covered with a conductive coating that provides adhesion to the current collector and ensures electronic transfer between the current collector and the electrode coating. However, this solution is expensive and brings a significant additional cost. Therefore, there is a need for a binder with good electrochemical resistance, providing good adhesion to a metal current collector via a solvent-free manufacturing process. It is also essential that said binder has a high affinity with the other ingredients of the solvent-free formulation so that during pressing this binder provides intimate cohesion. Summary of the invention According to a first aspect, the present invention relates to a binder in powder form comprising a polymer PI comprising monomeric units derived from a fluorinated monomer and a polymer P2 comprising at least one monomeric unit derived from a monomer M2 of formula R 1 R 2 C=C(R 3 )C(O)R in which the substituents R 1 , R 2 and R 3 are independently of eac