Electrode for lithium-ion battery comprising a binder formed from a blend of two polymers, the first polymer being a first polyacrylate or one of its derivatives, the second polymer being a second polyacrylate or a carboxymethyl cellulose or one of their derivatives, ink for producing such an electrode

Patent metadata

Field	Value
Publication number	US-11050054-B2
Application number	US-201716083828-A
Country	US
Kind code	B2
Filing date	Mar 7, 2017
Priority date	Mar 8, 2016
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

Electrode for a lithium storage battery, or a lithium battery, including: an active electrode material, made from silicon, a conductive agent, a binder comprising a mixture of two polymers: the first polymer having a first molecular weight, the first polymer being a first polyacrylate or one of its derivatives, the second polymer having a second molecular weight, the second polymer being a second polyacrylate or a carboxymethyl cellulose, or one of their respective derivatives. The first molecular weight is less than or equal to 400,000 g/mol and greater than or equal to 150,000 g/mol. The second molecular weight is greater than or equal to 650,000 g/mol and less than or equal to 4,000,000 g/mol.

First claim

The invention claimed is:

1. Electrode for a lithium storage battery, or a lithium battery, comprising:
an electrode active material made from silicon,
a conductive agent,
a binder comprising a mixture of two polymers:
a first polymer having a first molecular weight, the first polymer being a first polyacrylate or one of its derivatives,
a second polymer having a second molecular weight, the second polymer being a second polyacrylate or one of its derivatives,

wherein the first molecular weight is greater than or equal to 150,000 g/mol and less than or equal to 400,000 g/mol and
wherein the second molecular weight is greater than or equal to 650,000 g/mol and less than 4,000,000 g/mol.

2. Electrode according to claim 1 , wherein a degree of dissociation of the first polymer and the second polymer ranges from 35% to 100%.

3. Electrode according to claim 1 , wherein the first polymer and the second polymer are polyacrylates.

4. Electrode according to claim 3 , wherein:
the first molecular weight is greater than or equal to 150,000 g/mol, and less than or equal to 400,000 g/mol,
the second molecular weight is greater than or equal to 1,000,000 g/mol and less than or equal to 1,500,000 g/mol,
a degree of dissociation of the first and second polymers is greater than 90%.

5. Electrode according to claim 1 , wherein the first molecular weight is at most 67% by weight compared with the second molecular weight.

6. Electrode according to claim 1 , wherein a weight of the binder represents from 2% to 15% of a weight of the electrode.

7. Electrode according to claim 1 , wherein the silicon is in the form of nanoparticles, and the silicon forms an alloy with the lithium, the alloy is of Li x Si type, with x comprised between 0 and 3.75.

8. Electrode according to claim 1 , wherein the silicon is inserted in a micrometric matrix, and the silicon forms an alloy with the lithium, the alloy being of Li x Si type, with x comprised between 0 and 3.75.

9. Electrode according to claim 7 , wherein 90% of the silicon is in the form of nanoparticles, the nanoparticles presenting a size distribution of less than 300 nm.

10. Electrode according to claim 1 , wherein the electrode has a grammage ranging from 2.5 mg/cm 2 to 10 mg/cm 2 of deposited active material and a density of at least 1.4.

11. Electrode according to claim 1 , wherein the electrode does not contain any latex.

12. Electrode according to claim 1 , further comprising an additive, the additive representing 5% by weight or less of the electrode.

13. Ink for producing an electrode for a lithium-ion battery, comprising:
an electrode active material made from silicon,
a solvent,
a conductive agent,
a binder comprising a mixture of first and second polymers,
the first polymer having a first molecular weight, the first polymer being a first polyacrylate or one of its derivatives,
the second polymer having a second molecular weight, the second polymer being a second polyacrylate or a carboxymethyl cellulose, or one of their respective derivatives,

wherein the first molecular weight is greater than or equal to 150,000 g/mol and less than or equal to 400,000 g/mol and
wherein the second molecular weight is greater than or equal to 650,000 g/mol and less than 4,000,000 g/mol.

14. Ink according to claim 13 , wherein the first and second polymers has a degree of dissociation ranging from 35% to 100%.

15. Ink according to claim 13 , wherein the first polymer and the second polymer are polyacrylates.

16. Ink according to claim 13 , wherein the first polymer is a polyacrylate and the second polymer is a carboxymethyl cellulose.

17. Ink according to claim 13 , wherein the binder represents from 2% to 15% of the weight of the ink in a dried form.

18. Ink according to claim 13 , wherein the silicon is in the form of nanoparticles, the silicon being comprised or not in a micrometric matrix, and the silicon forms an alloy with the lithium of Li x Si type, with x comprised between 0 and 3.75.

19. Ink according to claim 18 , wherein 90% of the silicon in the form of nanoparticles presents a size distribution of less than 300 nm.

20. Electrode according to claim 1 , wherein the first molecular weight is at most 50% by weight compared with the second molecular weight.

21. Electrode according to claim 1 , wherein the first polymer and the second polymer are polyacrylates and wherein the weight ratio of the first polymer to the second polymer is greater than or equal to 1.

22. Electrode according to claim 3 , wherein:
the first molecular weight is greater than or equal to 250,000 g/mol and less than or equal to 400,000 g/mol,
the second molecular weight is greater than or equal to 1,000,000 g/mol and less than or equal to 1,500,000 g/mol,
a degree of dissociation of the first and second polymers is greater than 90%.

23. Electrode for a lithium storage battery, or a lithium battery, comprising:
an electrode active material made from silicon,
a conductive agent,
a binder comprising a mixture of two polymers:
a first polymer having a first molecular weight, the first polymer being a first polyacrylate or one of its derivatives,
a second polymer having a second molecular weight, the second polymer being a carboxymethyl cellulose,

wherein the first molecular weight is greater than or equal to 150,000 g/mol and less than or equal to 400,000 g/mol and
wherein the second molecular weight is greater than or equal to 650,000 g/mol and less than or equal to 4,000,000 g/mol.

Assignees

• Commissariat Energie Atomique
• Umicore Nv

Inventors

• Porcher Willy
• Barbier Frédéric
• Chazelle Sophie
• Mariage Nicolas
• Merchat Léo

Classifications

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/622 Primary

  being polymers · CPC title

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title