# US 11,898,257 B1 · Carbon coated electrodes

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- Number: US 11,898,257 B1
- Document ID: US11898257B1
- Status: Granted
- Kind: B1
- Application number: 18/264,610
- Filed: 2023-01-20
- Published: 2024-02-01
- Granted: 2024-02-13
- Earliest claimed: 2022-01-20
- Assignees: Nanofilm Technologies International Limited
- Applicants: Nanofilm Technologies International Limited
- Inventors: Zhi Tang; Ting Wang; Xu Shi
- Web page: https://patentgrep.com/patent/US11898257B1

## CPC

- C25B 1/04: by electrolysis of water
- C25B 11/04: characterised by the material
- C23C 14/35: by application of a magnetic field, e.g. magnetron sputtering {(C23C14/3457 takes precedence)}
- C25B 11/036: Bipolar electrodes
- C25B 11/052: Electrodes comprising one or more electrocatalytic coatings on a substrate
- C25B 11/065: Carbon
- H01M 8/0213: Gas-impermeable carbon-containing materials
- H01M 8/0228: in the form of layered or coated products
- H01M 2004/8694: {Bipolar electrodes}
- H01M 2008/1095: {Fuel cells with polymeric electrolytes}
- Y02E 60/50: Fuel cells
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

An electrode for electrochemical applications is coated with a layer of a-C, wherein the layer of a-C comprises at least 10 each of first and second sub-layers, being—(i) first sub-layers having high conductivity with a sp2 content of 60-95%, alternating with—(ii) second sub-layers having high corrosion resistance with a sp2 content of 50-90%, wherein the sp2 content of the first sub-layers is at least 3% greater than the sp2 content of the second sub-layers. A method of making such electrodes comprises: —a) depositing a first sub-layer comprising a-C, —b) depositing a second sub-layer comprising a-C wherein the sp2 content of the first sub-layer is at least 3% greater than the sp2 content of the second sub-layer, and—c) repeating the steps above to deposit at least 10 first sub-layers alternating with 10 second sub-layers, so as to produce the electrodes.

## Claims

### Claim 1

An electrode, coated with a layer of a-C, wherein the layer of a-C comprises at least 10 each of first and second sub-layers, being
(i) first sub-layers having high conductivity with a sp2 content of 60-95%, alternating with
(ii) second sub-layers having high corrosion resistance with a sp2 content of 50-90%,
wherein the sp2 content of the first sub-layers is at least 3% greater than the sp2 content of the second sub-layers.

### Claim 2 (depends on 1)

The electrode of claim 1, wherein the sp2 content of the first sub-layers is at least 7% greater than the sp2 content of the second sub-layers.

### Claim 3 (depends on 1)

The electrode of claim 1, wherein the first sub-layers have a sp2 content of 70-85% and the second sub-layers have a sp2 content of 60-80%.

### Claim 4 (depends on 1)

The electrode of claim 1, wherein the sub-layers each have thicknesses up to 5 nm.

### Claim 5 (depends on 4)

The electrode of claim 4, wherein the sub-layers each have thicknesses up to 3 nm.

### Claim 6 (depends on 5)

The electrode of claim 5, wherein the sub-layers each have thicknesses in the range 0.2 to 2 nm.

### Claim 7 (depends on 1)

The electrode of claim 1, wherein the electrode is a bipolar plate for a PEM hydrogen fuel cell.

### Claim 8 (depends on 1)

The electrode of claim 1, wherein the electrode is an electrode for hydrogen generation from water.

### Claim 9 (depends on 1)

The electrode of claim 1, wherein there are at least 20 each of the first and second sub-layers.

### Claim 10 (depends on 1)

A The electrode of claim 1, wherein
the layer of a-C comprises at least 30 of each of the alternating first and second sub-layers, the sub-layers each have thicknesses of about 0.8-2 nm,
the first sub-layers have a sp2 content of 70-85% and a sp3 content of 15-30%, and
the second sub-layers have a sp2 content of 65-80% and a sp3 content of 20-35%.

### Claim 11 (depends on 1)

The electrode of claim 1, wherein the layer of a-C has a molar hydrogen content of 1% or less.

### Claim 12 (depends on 1)

The electrode of claim 1, wherein the layer of a-C has an oxygen content of 1% or less.

### Claim 13 (depends on 1)

The electrode of claim 1, wherein the layer of a-C has a thickness of 2 μm or less.

### Claim 14 (depends on 13)

The electrode of claim 13, wherein the layer of a-C has a thickness of 1 μm or less.

### Claim 15 (depends on 1)

The electrode of claim 1, wherein the coating is deposited by Filtered Cathodic Vacuum Arc.

### Claim 16 (depends on 1)

The electrode of claim 1, wherein the sp2 content of the coating as a whole is at least 55%.

### Claim 17 (depends on 1)

A method of coating an electrode for electrochemical applications with a carbon-containing coating, the method comprising:
a) depositing a first sub-layer comprising a-C,
b) depositing a second sub-layer comprising a-C wherein the sp2 content of the first sub-layer is at least 3% greater than the sp2 content of the second sub-layer, and
c) repeating the steps above to deposit at least 10 first sub-layers alternating with 10 second sub-layers,
so as to produce the electrode of claim 1.

### Claim 18

A method of coating an electrode for use in electrochemical applications with a carbon-containing coating, the method comprising:
d) depositing a first sub-layer comprising a-C and having a sp2 content of 65-90% and a sp3 content of 10-35%,
e) depositing a second sub-layer comprising a-C and having a sp2 content of 45-80% and a sp3 content of 20-55%, and
f) repeating the steps above to deposit at least 10 first sub-layers alternating with 10 second sub-layers,
wherein the sp2 content of the first sub-layers is at least 3% greater than the sp2 content of the second sub-layers, and
wherein the sub-layers each have thicknesses in the range 0.3 to 5 nm.

### Claim 19 (depends on 18)

The method of claim 18, comprising depositing at least 30 alternating first and second sub-layers.

### Claim 20 (depends on 18)

The method of claim 18, for coating a bipolar plate, comprising:
depositing the first sub-layers by Filtered Cathodic Vacuum Arc while applying a first biasing regimen to the bipolar plate; and
depositing the second sub-layers by Filtered Cathodic Vacuum Arc while applying a second biasing regimen to the bipolar plate,
wherein the second biasing regimen is adjusted compared to the first so as to result in sp2 content in the a-C being decreased by at least 3% and sp3 content in the a-C being increased by at least 3%.

### Claim 21 (depends on 20)

The method of claim 20, wherein the biasing regimen comprises applying a biasing voltage according to a duty cycle, and the method comprises periodically adjusting the duty cycle, whereby adjusted duty cycle deposits the second-sub-layers having increased sp3 content and decreased sp2 content.