A Comprehensive Guide to Bipolar Plate Manufacturing Process

Electrolyzers and fuel cells rely on thin, engineered plates that do more than provide structure. The bipolar plate manufacturing process results in components that introduce, direct, and control various gases, conduct electricity, and control heat in the stack. Because thousands of plates may be required for one system, small differences in production can affect efficiency, durability, and total cost. Bipolar plate manufacturing is complicated because it must combine precision and tolerances with a resistance to severe environments. 

We will describe how these plates are produced, their importance, and where they are used.

Bipolar Plate Manufacturing Process

The bipolar plate manufacturing process is a multi-step process that turns raw metal material into highly specialized components, which will ultimately be utilized in fuel cells and electrolyzers. The steps involved are discussed below in more detail. 

Material Selection

The process begins with identifying the raw material to utilize. The choice of raw material will depend on whether the application requires higher conductivity, decreased corrosion resistance, or lower weight construction. 

• Stainless steel is the common choice as a construction material. Stainless steel provides a balance between strength and conductivity. 
• Titanium and specialty alloys can also be used in conjunction with bipolar plates in an environment with high-risk corrosion. 

The choice in the base construction material will establish the performance baseline for all of the plates in the stack.

Coating Methods

Coatings can be applied to both improve corrosion resistance and increase conductivity. There are two well-established ways to add coatings to bipolar plates, including: 

• Pre-coated material rolls in a roll-to-roll coating system before being shaped, or; 
• Post-coated after all of the bipolar plate manufacturing steps have been completed. 

The pre- or post-coating method will depend on the costs, design, or durability requirements of the bipolar plates.

Defining Geometry

Flow field geometry can also be adjusted for the individual design of the cell. This will be an iterative process and will depend on; 

• Patterns of gas distribution,
• Cooling requirements, and,
• Stack integration with membranes, seals, and diffusion layers.

Geometry is the most critical aspect associated with bipolar plates, as it can affect power density.

The Forming Process  

Forming is a process by which the metal sheet undergoes a transformation into its functional shape. Some of the methods include: 

• Stamping – a high-speed operation and easily scalable, 
• Hydroforming – a highly accurate method that uses high-pressure fluid to mold around whatever shape it’s needed, even tight tolerances, 
• Deep drawing or rotary forming – used to create complex geometries  in heavy-gauge metals, 

Choosing the right forming method is a balancing act of cost and performance requirements. 

Cutting and welding  

Once the plates have been formed, they must now be cut and connected:  

• Laser cutting creates burr-less edges – critical for function once in operation for extended periods of time.  
• Laser welding connects multiple plates with very fine tolerances to ensure that the stacks are free of leaks, and reliability is guaranteed.   
• Straighten, clean, and seal  

There are additional steps to ensure the final product is at its best:  

• Straightening is the process of removing any warpage or stresses placed on the substrate during forming.  
• Cleaning is how the plates will perform with regard to chemical and electrical stability.   
• Sealing – usually with screen printing, injection molding, or dispensing will complete the plates for assembly into stacks.  

Leak Testing  

The plates are leak tested – from differential testing to helium leak detection, every possible metric to ensure reliability in function will occur.    

The metal plate manufacturing process allows for simply manufactured parts, but bipolar plate manufacturing allows for tighter tolerances and very specific treatments of the end use. Overall, these steps help to produce components that contribute to a clean energy system with performance and longevity.

Importance of Bipolar Plates

Bipolar plates account for almost half of a fuel cell stack’s cost and up to 80 % of its weight. When you’re designing a bipolar plate, obviously, you can’t just focus on the weight; they’re doing more than occupying space between cells—they’re providing important functions such as:

• Gas management: distributing hydrogen and oxygen evenly over each of the electrodes, transporting water out of the stack, and moderating the stack temperature.
• Electrical continuity: conducting current from cell to cell in an effective manner to generate power.
• Structural support and sealing: holding the membrane-electrode assemblies together and sealing the stack from contaminants. 

These functions mean that even small changes that improve the design or manufacture a bipolar plate can increase power density, decrease losses, improve the lifetime of the system, so every design or engineering decision, from materials to channel patterns, is very important.

TMNetch Bipolar Plates

TMNetch is a specialized manufacturing company that uses advanced techniques to make high-performing bipolar plates. TMNetch’s bipolar plate manufacturing process extends beyond basic fabrication. They have 100+ engineers and chemists focused on developing etching technology with tighter tolerances and finer detail. Here are the notable benefits:

• Custom Etching with Multi-Depth Channel Design

TMNetch is able to photochemically etch flow channels and surface designs of varying depths, such as 0.6 mm and 0.4 mm on one side, as well as 0.5 mm on the other side, allowing for precise control of fluid and gas distribution.

• Unique Coating Abilities

The plate can have one side plated with platinum and the other side has an MMO (mixed metal oxide) coating. This dual-coating enhances performance and corrosion resistance.

• Laser-Welded Seal for Leaking-Free Assembly

TMNetch laser welds sealing grooves that are thin, smooth, and flush. This is important for reliable leak-free stacks.

• Fast Prototyping with Consistent Precision

Need designs tested quickly? TMNetch can supply prototypes within 6 hours and maintain tolerances of ± 0.05 mm.

• Qualified Personnel and Global Presence

Their custom bipolar plates are shipped with full documentation and COC support internationally with no problem for export/import.

FAQs About Bipolar Plate Manufacturing Process 

How to make a bipolar plate?

Bipolar plates are made using techniques such as photochemical etching, forming, coating, and sealing. The bipolar plate manufacturing processes established the flow fields, enabled corrosion protection, and completed preparation for stacking. 

What are bipolar plates made of?

The most widely used materials for bipolar plates include stainless steel, titanium, graphite, and composites. Metal bipolar plates are often chosen based on strength and conductivity, while other coatings are chosen to enhance durability for demanding PEM or alkaline applications. 

What manufacturing processes are used for plates?

Bipolar plates manufactured from metal faced a variety of choices in processing methods that could include stamping, hydroforming, or deep drawing. In contrast, photochemical etching offers precision and flexibility. 

How does a bipolar plate work? 

A bipolar plate separates and connects adjacent fuel cells while separating the gases. The distribution of the hydrogen and oxygen is achieved through flow channels in the plates. There are coatings that prevent corrosion and ensure conductivity. The bipolar plates help maintain stack efficiency by directing current and controlling heat and water. 

Conclusion 

The bipolar plate manufacturing process is the key component to building reliable and high-performance fuel cells and electrolyzers. From the material selection, etching and precision, coatings, sealing, etc., are all aspects that impact efficiency and lifespan directly. TMNetch has the experience and expertise to manufacture even the most complex designs into practical and durable components.