Graphite Microcrystalline Carbon Coating for Low-Resistance Fuel Cell Plates
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Solution Overview
Problem
Metal bipolar plates in fuel cells suffer from increased contact resistance and reduced corrosion resistance due to passivation in high-temperature, high-humidity environments, leading to voltage losses and reduced output power, with existing carbon coatings exhibiting high contact resistance and unknown durability.
Innovation Solution
A graphite micro-crystalline carbon coating is applied to metal bipolar plates, comprising a corrosion-resistant metal priming coating, a metal and carbon co-existing transition coating, and an outermost graphite micro-crystalline carbon coating, optimized through magnetron sputtering with controlled particle energy and temperature to enhance bonding, stability, and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal bipolar plates are used in fuel cells, then mechanical performance and corrosion resistance are improved, but contact resistance increases due to passivation in high-temperature high-humidity environments
Solution Approach 1:
The patent applies composite material structure by combining metal bipolar plate substrate with carbon coating layer. The metal provides mechanical strength and baseline corrosion resistance, while the carbon coating provides low contact resistance and enhanced corrosion resistance in high-temperature high-humidity environments, creating a composite structure that synergistically addresses both requirements.
Solution Approach 2:
The patent changes the physical and chemical parameters of the coating by controlling deposition temperature (150-600°C) and particle energy during magnetron sputtering. These parameter changes transform the carbon coating structure to achieve optimal conductivity, corrosion resistance, and adhesion properties that resolve the contradiction between metal substrate performance and contact resistance issues.
2Reliability
If amorphous carbon coating is applied to metal bipolar plates, then corrosion resistance is improved, but contact resistance remains high under working pressure
Solution Approach 1:
The patent fundamentally changes the coating structure by controlling deposition parameters (temperature 150-600°C, particle energy) to form graphite micro-crystalline structure instead of amorphous structure. This structural transformation reduces contact resistance while maintaining corrosion resistance, directly resolving the contradiction identified in prior art.
Solution Approach 2:
The patent creates different functional zones within the carbon coating through controlled deposition. The coating exhibits local quality variations where the micro-crystalline graphite structure provides low contact resistance at the contact interface, while the overall coating maintains corrosion resistance properties, addressing both requirements simultaneously.
3Object-affected harmful factors
If carbon coating is applied to reduce contact resistance, then conductivity is improved, but durability and stability deteriorate under cyclic loading and start-stop conditions
Solution Approach 1:
The patent applies preliminary action by depositing a corrosion-resistant metal priming coating before the carbon coating. This priming layer is applied in advance to prevent corrosion and enhance adhesion, which maintains coating integrity and durability under cyclic loading and start-stop conditions, resolving the durability issue while preserving low contact resistance.
Solution Approach 2:
The patent creates a multi-layer composite structure with metal priming coating, transition coating, and graphite micro-crystalline carbon coating. This composite structure provides both low contact resistance from the carbon layer and enhanced durability through the metal priming layer that prevents substrate corrosion and maintains adhesion under mechanical stress cycles.
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 coating achieves low contact resistance, improved corrosion resistance, and enhanced durability, reducing performance degradation and promoting the industrialization of fuel cells by maintaining conductivity and mechanical performance.
Implementation Method 1
the coating is prepared by means of magnetron sputtering
Implementation Method 2
particle energy during magnetron sputtering is increased to optimize the structure of the carbon coating
Data Source
AI summary
The invention relates to a graphite micro-crystalline carbon coating for metal bipolar plates of fuel cells and an application thereof. The graphite micro-crystalline carbon coating is a graphite-like coating deposited on the surface of a metal bipolar plate, includes, by weight, 5%-50% of graphite micro-crystals, and has good compactness. Based on conventional magnetron sputtering technologies, the energy of deposited particles is changed by changing a target sputtering power source, the intensity of a sputtering magnetic field and the deposition temperature of the coating to change the structure of the carbon coating, so that the carbon coating with high conductivity, corrosion resistance, and stability is prepared. Compared with the prior art, under a precondition where the preparation cost of the coating is not increased, the contact resistance of the metal bipolar plate of a fuel cell and a gas diffusion layer can be reduced, and the corrosion resistance of the carbon coating in an acidic environment of the fuel cell and the conductive stability of the carbon coating after a long-time test can be improved, which is of great significance for promoting the commercialization of fuel cells.