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EP-4490784-B1 - POWDEROUS POLYMER BINDER FOR HIGH VISCOUS PROCESSING FOR ANODE MANUFACTURE

EP4490784B1EP 4490784 B1EP4490784 B1EP 4490784B1EP-4490784-B1

Inventors

  • BRANDAU, SVEN
  • FRUEH, THOMAS
  • WIEGMANN, Eike
  • HASELRIEDER, WOLFGANG
  • KWADE, ARNO

Dates

Publication Date
20260506
Application Date
20230306

Claims (11)

  1. A composition comprising: - a non-spherical powderous cross-linked polymer obtained by grinding, wherein the cross-linked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl)methacrylate and trimethylolpropane trimethacrylate, and the non-spherical powderous cross-linked polymer has a particle size D(90) of 180 - 450 µm; and - a silica anti-caking agent.
  2. The composition according to claim 1, wherein the cross-linked polymer further comprises the monomer units acrylonitrile.
  3. The composition according to any one of the above claims, wherein the polymer comprises the monomer units in the following amounts 1,3 butadiene in a range of 99 to 32.5 wt%, (hydroxyethyl)methacrylate in a range of 0.5 to 10 wt%, trimethylolpropane trimethacrylate in a range of 0.5 to 7.5 wt% and acrylonitrile in a range of 0 to 50 wt%.
  4. The composition according to any one of the above claims, wherein the silica anti-caking agent is present in an amount of 3 - 15 wt% with respect to the cross-linked polymer.
  5. A use of the composition according to any one of the above claims as a binder for an anode of a rechargeable battery.
  6. An electrode composition for an anode of a rechargeable battery comprising: - the composition of any one of the above claims, - an active material; and - a conductive material.
  7. The electrode composition according to claim 5, wherein the active material is selected from at least one of carbon materials, a conductive polymer, a metal or alloy thereof or salt thereof or sulphate thereof or any combination thereof.
  8. The electrode composition according to any one of claims 5 - 6, wherein the conductive material is a carbon-based material.
  9. A process for the manufacture of an anode comprising: - providing to an extruder the composition according to any one of claims 1 - 4, - providing to the extruder an active material and a conductive material; and - laminating the resultant extrudate to a surface of an anode current collector.
  10. The process according to claim 9, wherein a total solids content of the composition according to any one of claims 1 - 4, an active material and a conductive material is at least 70wt%.
  11. The process according to claim 9, wherein the anode current collector comprises a metal selected from one of iron, copper, aluminium, nickel, stainless steel, titanium, tantalum, gold or platinum.

Description

Field of Invention The present invention describes a composition as a binder for an anode of a rechargeable battery. The composition comprises a non-spherical powderous cross-linked polymer which is obtained by grinding. The cross-linked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl)methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA) and the non-spherical powderous cross-linked polymer has a particle size D(90) of 180 - 450 µm; the composition further comprises a silica anti-caking agent. Background of Invention A rechargeable battery (also known as a storage battery, a secondary cell or an accumulator) is a type of electrical battery which can be charged, discharged and recharged many times. The rechargeable battery plays an important role for creating a greener and more sustainable future. The rechargeable battery comprises an anode, a cathode, an electrolytic solution and a separator. A binder is also present within the rechargeable battery and is usually a rubber polymer. The binder holds an active material and a conductive material which are then cast onto a current collector of the electrodes. The binder plays important roles regarding performance of the rechargeable battery. Firstly, the binder helps to disperse the other components (e.g. active material, conductive material) in liquid during casting onto a current collector (with some also acting as a thickener), enabling a homogeneous distribution. Second, the binder holds together the various components of the rechargeable battery, including the active material and the conductive material, with the current collector, ensuring good contact, through chemical or physical interactions, the binder bridges these separate components, keeping them together and ensuring mechanical integrity of the electrode without significantly impacting electronic or ionic conductivity during charging and discharging. Thirdly. The binder acts as an interface between the current collector and electrolyte and can thus protect the current collector from corrosion. The binder needs the following characteristics: flexible, insoluble in the electrolyte, have a good adherence to a current collector, be chemically and electrochemically stable and easy to apply to the current collector. To achieve the aforementioned characteristics a successful casting of the binder and e.g. the active material and the conductive material onto the current collector of the electrodes depends not only on the binder itself but also a casting method. EP3902855A1 discloses a powderous (pulverulent) composition comprising, a polymer consisting of the monomer units acrylonitrile, 1,3-butadiene and trimethylolpropane trimethacrylate (TMPTMA). The powderous (pulverulent) composition includes a silica anti-caking agent. The powderous (pulverulent) composition has an average particle diameter in the range 0.01 to 4 mm. The powderous (pulverulent) composition is used for a production of tyre treads, in which there is simultaneous improvement in wet skid resistance, dry grip and rolling resistance, with good mixing characteristics. EP3902855A1 does not disclose a polymer including the monomer units (hydroxyethyl)methacrylate (HEMA). EP3053938A discloses a microgel polymer comprising the monomer units acrylonitrile, 1,3-butadiene, (hydroxyethyl)methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA). The polymer is worked up by spray drying to provide spherical or virtually spherical microgel particle agglomerates with an average particle diameter of 2 to 500 µm. The microgel polymers are additives which can be incorporated easily into thermoset compositions such as plastics, for improving the impact strength and energy absorption to the point of fracture, while at the same time retaining the qualities such as mechanical strength, glass transition temperature and modulus of elasticity. An article by J.-H. Lee et al. (Journal of Power Sources 147 (2005) 249-255) discloses conventional methods of casting an anode surface using the emulsified styrene butadiene rubber (SBR) polymer and sodium carboxymethyl cellulose (CMC) mixture as anode binder. The article by J.-H. Lee et al discloses binder mixtures pre casting containing a solids weight fraction of 35% which is relatively low. US 2019/305316 A1 describes dry process electrode films, and energy storage devices incorporating the same, including a microparticulate non-fibrillizable binder having certain particle sizes. The electrode films are described to exhibit improved mechanical and processing characteristics. Also disclosed are methods for processing such microparticulate non-fibrillizable electrode film binders, and for incorporating the microparticulate non-fibrillizable binders in electrode films. There is a need to provide improved binder compositions, a use of the binder composition for an anode in a rechargeable battery and a process for the manufacture of an anode. Summary of Invention In a first aspect t