Advances in electrode and electrolyte materials of fiber-shaped supercapacitors for electrochemical performance improvement and applications extension

In wearable electronics, fiber-shaped supercapacitors (FSCs) have attracted significant attention due to their excellent flexibility and rapid charge-discharge rates. FSCs can not only conform to the body's contours during large deformations, such as twisting and stretching, but also exhibit faster charge-discharge rates and longer cycle life compared to other energy storage devices, such as lithium-ion fiber batteries and zinc-ion fiber batteries. These characteristics are critical for the durability and short-term response of wearable devices. This paper systematically reviews the latest research progress on fiber electrode materials and gel electrolytes in FSCs, providing an in-depth analysis of their advantages and limitations. To address the limitation of low energy density in FSCs, five effective strategies for optimizing electrochemical performance are discussed, with a focus on both the electrode and electrolyte systems. Furthermore, this paper summarizes recent developments and future trends in integrating multifunctionality (e.g., stretchability, biocompatibility, freeze resistance, fluorescence) and complex systems (e.g., energy harvesting and sensing systems) into single fiber devices.