A hierarchical layered double hydroxide electrode with surface porous microstructured fibers for flexible and wearable energy storage

The exploration of high-performance functional fiber materials with good wearability and mechanical properties for flexible energy storage devices is in ever-increasing demand but challenging. Commonly used fibers usually possess high internal resistance and small accessible areas, and the complicated manufacturing process due to the slender structure and non-planar surface has further limited their application potential. In this study, a facile strategy to fabricate a hydrothermally grown NiCo layered double hydroxide (LDH) on conductive porous microstructured stainless steel yarn (SSY@CPMs) electrode with hierarchical structures and mechanical stability was developed. The capacitive properties of the NiCo-SSY@CPMs showed a significant improvement owing to the high porosity and enhanced dispersive adhesion. An advanced all-solid-state asymmetric supercapacitor (ASC) device with great electrochemical performance and excellent mechanical reliability based on the NiCo-SSY@CPMs electrode was further assembled. The device showed a maximum energy density of 22.52 μW h cm⁻² and power density of 7.43 mW cm⁻², and meanwhile possessed great cycling performance. More importantly, given the outstanding flexibility and robustness of this fiber-shaped ASC device, it can be directly sewn onto common fabrics and power commercial electronics. This strategy may shed light on the rational design of advanced functional fibers as efficient energy storage electrodes through precise manipulation of surface microstructures.