Review of Bipolar Plate in Redox Flow Batteries: Materials, Structures, and Manufacturing

Interest in large-scale energy storage technologies has risen in recent decades with the rapid development of renewable energy. The redox flow battery satisfies the energy storage demands well owing to its advantages of scalability, flexibility, high round-trip efficiency, and long durability. As a critical component of the redox flow battery, the bipolar plates provide mechanical support for the electrodes and act as a physical separator between adjacent cells, as well as constructing the internal circuit and guiding the electrolyte flow. The present work offers a comprehensive review of the development of bipolar plates in redox flow batteries, covering materials, structures, and manufacturing methods. In terms of materials, the effects of material types and composition on the compactness, mechanical strength, and electrical conductivity are summarized in detail. Furthermore, the corrosion mechanisms of bipolar plates and the corresponding detection and mitigation methods are discussed. In addition, the structures of the bipolar plates refer to the flow field designs on the surface. The advantages and disadvantages of these existing flow fields are described, and the tendencies for further optimization are also discussed. The manufacturing of composite bipolar plates in terms of material cost and preparation methods is also outlined. Based on the summary of previous research, this work provides suggestions for the future development of high-performance bipolar plates. Graphical Abstract