Bipolar Carbon Separator for Redox Flow Battery

FJ composite manufactures the bipolar plates for redox flow battery (RFB) with carbon powder and synthetic resin by means of molding. After extensive research on materials and manufacturing methods, we have massively produced high quality bipolar plates with a full automated manufacturing equipment. Bipolar plates are the main components of RFBs, and high corrosion resistance and electrical conductivity are required. We have developed a unique manufacturing technology with carbon powder and highly corrosion-resistant thermoplastic resin.

Materials and Structures

The mold press, formed with carbon powder and resin, achieves the required performance by blending suitable materials.
It is freely designed on the channel shape and channel width, and different shapes can be designed on the front and back sides.

Physical property table for carbon separators with various resins

Physical property table for carbon separators with various resins

Physical Properties


Volume resistivity
under 5mΩcm

Bending strength
over 35MPa

High-precision flatness

Large carbon bipolar plates can be produced
950mm x 450mm

Various thicknesses can be accommodated
Ranging from approximately 1mm to 10mm

Low-cost, high-cycle molding
Independent development has been conducted from material selection

The proprietary developed product demonstrates high bending strength

The proprietary developed product demonstrates high bending strength

Cost Performance

Full automation achieved through in-house developed bipolar plate molding line (S-MARC system).
By thoroughly reviewing the manufacturing process, we have established an efficient production line that can operate 24 hours a day without manpower, resulting in significant reduction in labor costs.

Single-point prototyping is possible
We also accommodate various groove patterns. Please contact us with your desired shape as a starting point.

S-MARC System

S-MARC System

Technology Solutions

Safety and long-life

One of the benefits of a redox flow battery (RFB) is its ability to easily and safely store a large amount of electricity.
While it is generally not easy to store electricity, RFBs can do so safely and have a long lifetime


Small batteries are used daily due to their convenience, but safety becomes a concern when it comes to large size batteries.
Pumped storage can store large amounts of electricity by converting power into potential energy, although it is only about 50% efficient. In contrast, batteries can store power with a conversion efficiency of 90%.

②Stable supply

It is commonly believed that a nuclear power plant can provide a stable and highly efficient supply of electricity.
Once it starts operating, it is difficult to stop quickly and can run continuously 24 hours a day, 7 days a week.
While renewable energy is eco-friendly, it cannot provide a stable power supply. Photovoltaic power can only generate electricity during the daytime, and wind turbines require wind to generate power.
However, by combining these renewable energy systems with a large battery, such as an RFB, a stable power supply can be achieved.

To reduce carbon emissions, the Japanese government has set a target of 22-24% renewable energy in the power supply mix by 2030.
There are various types of energy storage batteries available, but the redox flow battery is expected to be the most suitable due to its safety, cost-effectiveness, and long life.

FJC Products

FJC Products



  • Nominated for the Advanced substrate technology for small and medium-sized enterprises (RFB Separator) by Ministry of Economy, Trade, and Industry
  • New Energy Technology Innovation Support Project for venture companies by the new energy and industrial technology development organization