Carbon Nanotube‐Based Flexible Fiber Energy Storage Devices: A Review of Fabrication, Modification, and Stretchability Enhancement Strategies

ABSTRACT With the rapid development of portable and wearable electronics, flexible fiber‐shaped energy storage devices have emerged as important solutions due to their lightweight nature, long cycle life, and high safety. High‐performance electrode materials are key to enhancing electrochemical performance. Carbon nanotubes (CNTs), with their 1D nanostructure, excellent mechanical properties, and ultra‐high tensile strength, are considered ideal for constructing flexible energy storage electrodes, particularly in applications balancing flexibility and electrochemical performance. Recent years have seen significant progress in CNT‐based flexible electrode research. To meet the demand for high‐capacity flexible energy storage, this review focuses on CNT‐based fiber‐shaped devices, which exhibit high capacity and excellent mechanical flexibility. It summarizes recent advancements in energy storage, emphasizing fabrication and modification techniques for fiber electrodes and strategies for improved flexibility and stretchability. Furthermore, the structural design and performance of devices based on preparation methods are elaborated in detail, alongside a discussion of their wearable application potential. This review also addresses core challenges in the field and outlines future research directions for advancing fiber‐shaped energy storage devices.