Graphite bipolar plate is a key component used in electrochemical equipment such as fuel cells and electrolyzers, usually made of high-purity graphite materials. It plays a vital role in electrochemical reactions, mainly used to conduct current, distribute reaction gases (such as hydrogen and oxygen), and separate reaction areas. Because its two sides contact the anode and cathode of adjacent single cells, forming a “bipolar” structure (one side is the anode flow field and the other side is the cathode flow field), it is named bipolar plate.
The structure of graphite bipolar plate
Graphite bipolar plates usually consist of the following parts:
1. Flow Field: The surface of the bipolar plate is designed with a complex flow field structure to evenly distribute the reaction gas (such as hydrogen, oxygen or air) and discharge the generated water.
2. Conductive layer: Graphite material itself has good conductivity and can conduct current efficiently.
3. Sealing area: The edges of bipolar plates are usually designed with sealing structures to prevent gas leakage and liquid penetration.
4. Cooling channels (optional): In some high-performance applications, cooling channels may be designed inside the bipolar plates to regulate the operating temperature of the equipment.
Functions of graphite bipolar plates
1. Conductive function:
As the electrode of electrochemical equipment, the bipolar plate is responsible for collecting and conducting current to ensure efficient output of electrical energy.
2. Gas distribution:
Through flow channel design, the bipolar plate evenly distributes the reaction gas to the catalyst layer, promoting the electrochemical reaction.
3. Separating reaction zones:
In a fuel cell or electrolyzer, bipolar plates separate the anode and cathode areas, preventing gases from mixing.
4. Heat dissipation and drainage:
Bipolar plates help regulate the operating temperature of the equipment and discharge water or other by-products generated by the reaction.
5. Mechanical support:
Bipolar plates provide structural support for the membrane electrode , ensuring the stability and durability of the equipment.
Why choose graphite as bipolar plate material?
Material properties of graphite bipolar plates
● High conductivity:
The bulk resistivity of graphite is as low as 10-15μΩ.cm (better than 100-200 μΩ·cm of metal bipolar plate) .
● Corrosion resistance:
Almost no corrosion in the acidic environment of fuel cells (pH 2-3), and the service life can reach more than 20,000 hours .
● Lightweight:
Density is about 1.8 g/cm3 (7-8 g/cm3 for metal bipolar plate), which is beneficial for reducing weight in vehicle applications.
● Gas barrier property:
The dense structure of graphite can effectively prevent hydrogen penetration and has high safety .
● Easy processing:
Graphite material is easy to process and can customize complex flow channel designs and sizes according to needs.
How are graphite bipolar plates manufactured?
The production process of graphite bipolar plate includes the following:
● Raw material preparation:
Use high purity (>99.9%) natural graphite or artificial graphite powder.
Add resin (such as phenolic resin) as a binder to enhance mechanical strength.
● Compression Molding:
The mixed material is injected into a mold and pressed under high temperature (200-300℃) and high pressure (>100 MPa).
● Graphitization treatment:
Heating to 2500-3000℃ in an inert atmosphere causes non-carbon elements to volatilize and form a dense graphite structure.
● Runner processing:
Use CNC machines or lasers to carve out serpentine, parallel or interdigitated channels (depth 0.5-1 mm).
● Surface treatment:
Impregnation with resin or metal (such as gold, titanium) coating reduces contact resistance and improves wear resistance.
What are the applications of graphite bipolar plates?
1. Fuel Cell:
- Proton exchange membrane fuel cell (PEMFC)
- Solid Oxide Fuel Cell (SOFC)
- Direct Methanol Fuel Cell (DMFC)
2. Electrolyzer:
- Hydrogen production by water electrolysis
- Chlor-alkali industry
3. Energy storage system:
- Flow battery
4. Chemical Industry:
- Electrochemical Reactor
5. Laboratory research:
- Prototype development and testing of fuel cells and electrolyzers
Summarize
Graphite bipolar plates are core components of electrochemical equipment such as fuel cells and electrolyzers, and have multiple functions such as conductivity, gas distribution, and separation of reaction areas. With the development of clean energy technology, graphite bipolar plates are increasingly used in new energy vehicles, energy storage systems, chemical hydrogen production and other fields.
Post time: Mar-31-2025