Acta Phys. -Chim. Sin. ›› 2021, Vol. 37 ›› Issue (9): 2009095.

Special Issue: Fuel Cells

• REVIEW •

### Graphite-Filled Composite Bipolar Plates for Fuel Cells: Material, Structure, and Performance

Runlin Fan1, Yuhang Peng1, Hao Tian1, Junsheng Zheng1,2,*(), Pingwen Ming1,2,*(), Cunman Zhang1,2

1. 1 School of Automotive Studies, Tongji University, Shanghai 200092, China
2 New Energy Automotive Engineering Center, Tongji University, Shanghai 200029, China
• Received:2020-09-29 Accepted:2020-10-23 Published:2020-11-09
• Contact: Junsheng Zheng,Pingwen Ming E-mail:jszheng@tongji.edu.cn;pwming@tongji.edu.cn
• About author:Emails: pwming@tongji.edu.cn (P. M.)
Emails: jszheng@tongji.edu.cn (J. Z.)
• Supported by:
the National Key R & D Program of China(2020YFB1505904);the Shanghai Committee of Science and Technology, China(17DZ1200403)

Abstract:

Bipolar plates (BPs) are one of the key components of proton exchange membrane fuel cell (PEMFC) stacks. To ensure that such a stack operates stably, a BP needs to meet exhibit electrical conductivity, heat conduction, H2 airtight, flexural strength, and durability. Based on these requirements, the BP should also be as thin as possible to reduce the overall cost of PEMFCs, while improving their volumetric energy density. A composite bipolar plate (CBP) exhibits the advantages of a low production cost, low processing difficulty, and corrosion resistance; it is produced using polymers and graphite as the main materials. Moreover, channel structures can be formed directly after a compression molding process. However, the trade-off that exists between electrical conductivity and flexural strength is a major challenge. The electrical conductivity of a CBP is realized through the network formed by graphite materials. Therefore, it not only depends on the filler concentration, but also on the network structure. At the same time, microstructures such as accumulation polymers and graphite/resin interface are directly related to the gas tightness and flexural strength of CBP. This review summarizes the conductive fillers and polymers that are commonly used for fabricating CBPs. The universal modification methods for both (fillers and polymers) are discussed, and a brief description of the conductive theoretical model has also been included. In addition, the advanced production technology of CBP is summarized, which includes the organization of the conductive network, elimination of the polymer on the plate surface, and preparation technology of the layered plates. The relationship between the production process and the performance of the plate was also analyzed. Some studies indicate that the conductive network can be optimized by combining kinds of carbon-based filler or electric field inducing, which could significantly promote the electrical conductivity of CBP. Flexural strength and H2 permeation rates were increased by introducing carbon-based materials such as carbon fabric and graphite foil. The modification of the filler and polymer could facilitate their bonding with each other, which reduces agglomeration and increases the performance. It is worth noting that the structure had a notable influence on the performance of CBP, which was reflected in the filler/polymer interface or the hybrid layer structure. Based on this results, some ideas have been provided as the next steps that can be taken for the optimization and production of a CBP. We believe that the optimization of the CBP structure will be the key point for its future research.

MSC2000:

• O646