Binder for lithium ion rechargeable battery cells

Patent metadata

Field	Value
Publication number	US-10050275-B2
Application number	US-201013265473-A
Country	US
Kind code	B2
Filing date	May 7, 2010
Priority date	May 11, 2009
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

An electrode for lithium ion recharged battery cell includes current collectors, a cathode layer, a separator and a cohesive anode mass. The cohesive anode mass includes silicon as an active material and a polymeric binder. The polymeric binder is a homo-polymer or copolymer of one or more monomers selected from the group consisting of acrylic acid, 3-butenoic acid, 2-methacrylic acid, 2-pentenoic acid, 2,3-dimethylacrylic acid, 3,3-dymethylacrylic acid, trans-butenedioc acid, cis-butenedioc acid and itaconic acid and optionally an alkali metal salt thereof. The silicon can include 20 to 100% of the active material in the cohesive mass. The binder is mixed with the silicon to form the cohesive mass that adheres to the current collector and maintains the cohesive mass in electrical contact with the current collector.

First claim

The invention claimed is:

1. An electrode for a lithium ion rechargeable battery cell comprising:
a current collector;
a cohesive mass disposed against the current collector, the cohesive mass comprising:
an active material comprising
20 to 100 wt % of a plurality of active silicon particulates, each of the plurality of the active silicon particulates having a purity of at least 95.00 wt % silicon,
the active material being present in the cohesive mass in an amount within the range of 50-95% of the total weight of the cohesive mass; and

a polymeric binder comprising a homopolymer of polyacrylic acid or an alkali metal salt thereof, each monomeric unit of the homopolymer having the structural formula (—CH 2 —CH—(COOX)—) in which each X is H or an alkali metal ion, the homopolymer of polyacrylic acid or the alkali metal salt thereof making up at least 25 wt % of the total binder content of the electrode,

wherein the polymeric binder and active material are mixed together such that the polymeric binder binds together the plurality of active silicon particulates such that the polymeric binder is in contact with the silicon particulates, to form the cohesive mass, which adheres to and remains in electrical contact with the current collector, and
wherein the electrode is capable of maintaining substantially constant discharge capacity during charging/discharging cycling for at least 150 cycles.

2. An electrode according to claim 1 , wherein the active silicon particulates are one or more of silicon particles, silicon fibres and silicon pillared particles.

3. An electrode according to claim 1 , wherein the active silicon particulates have a purity of less than 99.8 wt % silicon.

4. An electrode according to claim 1 , wherein the active silicon particulates have a purity of greater than 98 wt % and less than 99.8 wt % silicon.

5. An electrode according to claim 1 , wherein the active silicon particulates comprise 99.6 wt % silicon.

6. An electrode according to claim 1 , wherein the active silicon particulates comprise 99.7 wt % silicon.

7. An electrode according to claim 1 , wherein the polymeric binder comprises a mixture of the homopolymer of polyacrylic acid and a second binder.

8. An electrode according to claim 7 , wherein the second binder is an elastomeric binder selected from carboxymethyl cellulose (CMC) and/or polyvinylidinedifluoride or a mixture thereof.

9. An electrode according to claim 1 , wherein the homopolymer of polyacrylic acid has a molecular weight of greater than 50,000.

10. An electrode according to claim 1 , wherein the cohesive mass further includes a conductivity-enhancing material.

11. An electrode according to claim 10 , wherein the conductivity-enhancing material comprises one or more materials selected from carbon black and acetylene black.

12. An electrode as claimed in claim 1 , which is an anode.

13. An electrode according to claim 1 , wherein the active material further comprises greater than 0% and up to 80% of active carbon selected from graphite and/or hard carbon, wherein the polymeric binder binds together the plurality of active silicon particulates the active carbon.

14. A lithium ion cell including an electrode as claimed in claim 1 .

15. A device including an electrode according to claim 1 or a lithium ion cell according to claim 14 .

16. An electrode according to claim 1 , wherein the cohesive mass consists of the active material, the polymeric binder and optionally at least one conductivity-enhancing material.

17. An electrode according to claim 1 , wherein the silicon particulates further comprise one or more impurities selected from a group consisting of aluminum, boron, phosphorus or carbon in an amount up to 0.2 wt % each.

18. An electrode according to claim 1 , wherein the cohesive mass comprises between 76 to 80 wt % of the active material, between 8 and 12 wt % of the polymeric binder and 12 wt % of a conductive carbon.

19. The electrode of claim 1 , wherein the electrode is capable of maintaining substantially constant discharge capacity during charging/discharging cycling for at least 300 cycles.

20. The electrode of claim 1 , wherein substantially constant discharge capacity is about 1,200 mAh/g.

21. The electrode of claim 19 , wherein the substantially constant discharge capacity is about 1,200 mAh/g.

22. The electrode of claim 1 , wherein the electrode has a first cycle loss of 20% or less.

23. The electrode of claim 1 , wherein the electrode is has a total delithiation capacity of at least 500 mA hr.

24. The electrode of claim 1 , wherein the polymeric binder binds to the silicon particulates.

25. An electrode according to claim 1 , wherein each of the silicon particulates is selected from a silicon particle, a silicon fiber, a sheet-like silicon particle, a pillar-like silicon particle, a ribbon-like silicon particle, or a pillared silicon particle.

26. An electrode according to claim 1 , wherein each of the silicon particulates is selected from a silicon particle having a diameter in the range of 3 to 15 microns, a silicon fiber having a diameter in the range of 80 to 500 nm and a length in the range of 20 to 300 microns, and a pillared particle having a diameter in the range of 15 to 25 microns and a pillar height in the range of 1 to 4 microns.

27. An electrode according to claim 1 , wherein each of the silicon particulates has a purity of greater than 98% wt % silicon.

28. An electrode according to claim 1 , wherein each of the silicon particulates has a purity of less than 99.8 wt % silicon.

29. An electrode according to claim 1 , wherein the polymeric binder comprises at least 90 wt % of the homopolymer of poly(acrylic acid) or the alkali metal salt thereof.

30. An electrode according to claim 1 , wherein the active material is present in the cohesive mass in an amount within the range of 50-90% of the cohesive mass.

31. An electrode according to claim 1 , wherein the cohesive mass does not include an active carbon material.

Assignees

• Loveridge Melanie J
• Lain Michael Jonathan
• Kronfli Esam
• Nexeon Ltd

Inventors

• Loveridge Melanie J
• Lain Michael Jonathan
• Kronfli Esam

Classifications

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M4/134 Primary

  Electrodes based on metals, Si or alloys · CPC title

• H01M4/622

  being polymers · CPC title

• H01M10/052

  Li-accumulators · CPC title

• Y10T29/49115

  including coating or impregnating · CPC title