A review of flywheel energy storage rotor materials and structures

The flywheel is the main energy storage component in the flywheel energy storage system, and it can only achieve high energy storage density when rotating at high speeds. Choosing appropriate flywheel body materials and structural shapes can improve the storage capacity and reliability of the flywheel. At present, there are two main types of flywheel materials: metal materials and composite materials. The design and processing technology of metal materials is relatively mature. Composite materials have the characteristics of high strength and low density, which can achieve higher energy storage density, while the manufacturing process of composite materials is more complex, and the understanding of failure modes is not yet mature. This article introduces the evaluation indicators of flywheel rotor. The material characteristics of metal flywheel rotor and composite flywheel rotor are introduced. The performance characteristics of composite materials with different structures are also emphasized. Different flywheel structures are introduced and explained through application examples. In order to fully utilize material strength to achieve higher energy storage density, rotors are increasingly operating at extremely high tip speeds. However, this trend will lead to severe centripetal stress and potential safety threats caused by rotor failure. This article summarizes and elaborates on this issue. Finally, a summary was made on the material and structural design issues of the flywheel rotor. •The evaluation indicators of flywheel rotor•The force analysis model of flywheel rotor•The material characteristics of metal flywheel rotor and composite flywheel rotor•Structure design of flywheel rotor•Key directions for future research on flywheel rotor