Thermoplastic carbon composite electrodes

Patent metadata

Field	Value
Publication number	US-2020286643-A1
Application number	US-202016881824-A
Country	US
Kind code	A1
Filing date	May 22, 2020
Priority date	Feb 7, 2017
Publication date	Sep 10, 2020
Grant date	—

Abstract

A new solvent-based method is presented for making low-cost composite graphite electrodes containing a thermoplastic binder. The electrodes, termed thermoplastic electrodes (TPEs), are easy to fabricate and pattern, give excellent electrochemical performance, and have high conductivity (1500 S m −1 ). The thermoplastic binder enables the electrodes to be hot embossed, molded, templated, and/or cut with a CO 2 laser into a variety of intricate patterns. These electrodes show a marked improvement in peak current, peak separation, and resistance to charge transfer over traditional carbon electrodes. The impact of electrode composition, surface treatment (sanding, polishing, plasma treatment), and graphite source were found to impact fabrication, patterning, conductivity, and electrochemical performance. Under optimized conditions, electrodes generated responses similar to more expensive and difficult to fabricate graphene and highly oriented pyrolytic graphite electrodes. These TPE electrodes provide an approach for fabricating high-performance carbon electrodes with applications ranging from sensing to batteries.

First claim

What is claimed is:

1 . A method of preparing a thermoplastic electrode comprising:
a) dissolving a thermoplastic binder in a solvent to form a solution; b) combining a carbon allotrope and the solution to form a thermoplastic mixture; c) at least partially drying the thermoplastic mixture to form a thermoplastic composite; d) shaping the thermoplastic composite; and e) etching the thermoplastic binder at the surface of thermoplastic composite, thereby at least partially exposing the carbon allotrope; wherein the thermoplastic composite is in electrical contact with an electrical conductor to form a thermoplastic electrode having an active surface and a surface roughness of about 0.1 μm to about 5 μm.

2 . The method of claim 1 wherein the thermoplastic binder comprises poly(methyl methacrylate), poly-caprolactone, polyethylene, polycarbonate, polylactic acid, polyamide, polyimide, acrylonitrile butadiene styrene, polybenzimidazole, polypropylene, polystyrene, polyvinyl chloride, polyphenylene sulfide, polyphenylene oxide, polyether sulfone, polyoxymethylene, polyetherether ketone, polyetherimide, polyurethanes, polyolefin, ionic liquids, or a combination thereof.

3 . The method of claim 2 wherein the carbon allotrope comprises graphite, expanded graphite, graphite oxide, graphene, boron doped diamond, graphene oxide, glassy carbon, vitreous carbon, carbon nanotubes, carbon black, carbon fiber, fullerenes, or a combination thereof.

4 . The method of claim 3 wherein the carbon allotrope comprises graphite, and the graphite has a particle diameter of about 0.1 μm to about 300 μm.

5 . The method of claim 3 wherein a mass ratio of binder:graphite is about 1:0.5 to about 1:6.

6 . The method of claim 2 wherein the thermoplastic composite is viscous or has gum-like consistency.

7 . The method of claim 1 wherein shaping comprises molding, cutting, embossing, sanding, or a combination thereof.

8 . The method of claim 1 wherein shaping is performed at about the glass transition temperature (Tg) of the thermoplastic composite, about less than 20° C. below Tg, or about less than 20° C. above Tg.

9 . The method of claim 1 wherein the shaping comprises applying pressure to the thermoplastic composite, wherein a gasket is between a surface of the thermoplastic composite and a surface applying the pressure.

10 . The method of claim 1 wherein the solvent comprises lower alkyl halogenated alkanes, lower alkyl ketones, lower alkyl ethers, lower alkyl esters, lower alkyl alcohols, lower alkyl amides, lower alkyl sulfoxides, toluene, xylene, or a combination thereof.

11 . The method of claim 1 wherein etching is performed by sanding, polishing, plasma exposure, laser, sonication, electrochemical conditioning, solvent wiping, or a combination thereof.

12 . The method of claim 11 wherein the thermoplastic electrode is characterized by a peak separation that is approximately Nernstian, or the thermoplastic electrode is characterized by a kinetic charge transfer value of about 0.1 ohm cm 2 to about 4 ohm cm 2 .

13 . The method of claim 1 wherein the thermoplastic electrode has a conductivity of about 10-fold to about 1500-fold higher than a screen-printed carbon electrode, or the thermoplastic electrode has a conductivity of about 100 S m −1 to about 5000 S m −1 .

14 . The method of claim 1 wherein the thermoplastic composite comprises a catalyst.

15 . The method of claim 14 wherein the catalyst is a metal, metal oxide, metal coordination complex, alloy, enzyme, or organic molecule.

16 . The method of claim 1 wherein the thermoplastic composite has negligible porosity.

17 . The method of claim 1 wherein shaping the thermoplastic composite comprises a substrate that has a 2-dimensional pattern, a 3-dimensional pattern, or a combination thereof.

18 . The method of claim 1 wherein the thermoplastic composite is shaped to have a pattern diameter or width of about 0.1 μm to about 500 μm.

19 . A method of preparing a thermoplastic electrode comprising:
a) dissolving a poly(methyl methacrylate) binder in a solvent to form a solution; b) combining a carbon allotrope and the solution to form a thermoplastic mixture; c) at least partially drying the thermoplastic mixture to form a thermoplastic composite; d) shaping the thermoplastic composite into a pattern having a pattern diameter or width of about 0.1 μm to about 500 μm; and e) etching the thermoplastic binder at the surface of thermoplastic composite, thereby at least partially exposing the carbon allotrope; wherein the thermoplastic composite is in electrical contact with an electrical conductor to form a thermoplastic electrode having an active surface and a surface roughness of less than 5 μm.

20 . The method of claim 19 wherein a mass ratio of binder:allotrope is about 1:0.5 to about 1:6.

21 . The method of claim 19 wherein the carbon allotrope has a particle diameter of about 0.1 μm to about 300 μm.

Assignees

• Univ Colorado State Res Found

Inventors

• Henry Charles S
• Klunder Kevin

Classifications

• C08L55/02

  ABS [Acrylonitrile-Butadiene-Styrene] polymers · CPC title

• C08L25/06

  Polystyrene · CPC title

• C08K2201/005

  Additives being defined by their particle size in general · CPC title

• C08K2201/001

  Conductive additives · CPC title

• C08K3/38

  Boron-containing compounds · CPC title