Amorphous Carbon Electrode Coating for Conductivity and Corrosion Resistance

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Solution Overview

Problem

Existing electrode plates for hydrogen fuel cells and electrolysis applications face a trade-off between conductivity and corrosion resistance, with coatings designed for one property often compromising the other.

Innovation Solution

The use of a multi-layer carbon-containing coating comprising alternating sub-layers with high sp2 content for conductivity and high sp3 content for corrosion resistance, applied to bipolar plates and electrodes, specifically using amorphous carbon (a-C) with a seed layer, interfacial layer, and a top layer of a-C sub-layers to enhance both properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a corrosion resistant coating is applied to metallic bipolar plates, then corrosion resistance is improved, but conductivity is compromised

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidconductivity

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The carbon coating is segmented into multiple alternating sub-layers with different sp2/sp3 ratios. High sp2-content sub-layers (≥70%) provide conductivity, while high sp3-content sub-layers (≥30%) provide corrosion resistance. This segmentation allows both properties to coexist in different parts of the coating structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating is a composite structure combining carbon layers with different sp2/sp3 ratios. This composite approach integrates the conductive properties of sp2-rich regions with the protective properties of sp3-rich regions, achieving both high conductivity and corrosion resistance simultaneously.

Inventive Principle:

Principle #40Composite materials

2Reliability

If gold coating is used on bipolar plates, then corrosion resistance is improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive gold coating with a carbon-based coating that can be applied using cost-effective deposition techniques. The carbon coating achieves comparable corrosion resistance without the high material and processing costs associated with gold, making the bipolar plates more economically viable.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If a single-layer carbon coating is applied, then application process is simplified, but both conductivity and corrosion resistance cannot be optimized simultaneously

Engineering Contradiction:

Improvecoating structureVSAvoidcombined conductivity and corrosion resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The coating is divided into multiple sub-layers with distinct sp2/sp3 ratios. This segmentation enables each sub-layer to specialize in one function (conductivity or corrosion resistance), and the alternating structure ensures both functions are present throughout the coating thickness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating structure exhibits periodic alternation between high sp2-content layers and high sp3-content layers. This periodic structure creates a repeating pattern of conductive and protective zones, optimizing both properties through rhythmic variation in composition.

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution achieves a favorable combination of conductivity and corrosion resistance, reducing ion leaching and interfacial contact resistance while maintaining high conductivity, making the electrodes suitable for PEM fuel cells and hydrogen generation, and offering a cost-effective alternative to gold-coated plates.

Implementation Method 1

first sub-layers having high conductivity with a sp2 content of 60-95%, alternating with second sub-layers having high corrosion resistance, with a sp2 content of 50-90%

Methodology Applied

Scientific Effectsp2 hybridization:

Implementation Method 2

first sub-layers having high conductivity with a sp2 content of 60-95%, alternating with second sub-layers having high corrosion resistance, with a sp2 content of 50-90%

Methodology Applied

Scientific Effectsp3 hybridization:

Implementation Method 3

the electrode is coated with a carbon-containing coating, wherein the carbon-containing coating comprises a-C

Methodology Applied

Scientific EffectAmorphous carbon deposition: Deposition (physical)

Data Source

PatentUS11898257B1Carbon coated electrodes

Publication Date: 2024.02.13 NANOFILM TECH INT LTD

AI summary

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.