Self-supported Layered heterostructure derived from recycling waste silk for high performance low-temperature sodium storage

Abstract

The performance decay of flexible sodium-ion batteries (FSIBs) under extreme conditions stems from multiphysics failure of conventional electrodes in coupled low-temperature and deformation environments, typically including interfacial pulverization from active material expansion, conductive network fracture due to unidirectional stress release, and sluggish ion diffusion kinetics at low temperatures. To address this challenge, we propose a “stress-dissipative driven layered heterostructure” design concept, in which SnS2/FeS2 heterogeneous nanosheets with wavy surface morphology and a three-dimensional interconnected framework are in-situ constructed on silk-derived hard carbon cloth via hydrothermal synthesis. This unique architecture enables multidirectional stress dissipation and rapid, multidimensional ion/electron transport, while the self-supported design intrinsically enhances flexibility by eliminating rigid binders and current collectors. Concurrently, abundant Sn-Fe hetero-interfaces created through their synergy effectively boost low-temperature reaction kinetics. Consequently, the fabricated textile-based composite electrodes (TCEs) exhibit excellent rate performance (0.26 mAh cm−2 at a current density of 5 mA cm−2) and robust cycling stability, retaining capacity over 1000 cycles at 2 mA cm−2. Notably, the TCEs maintain reliable power supply for electronic watches even at ultra-low temperatures (-50°C). Additionally, the TCEs withstand up to 1500 bending cycles at a curvature radius of 0.5 cm due to localized structural modifications that disperse and absorb external forces. This work offers a scalable design paradigm toward high-energy-density flexible electrodes for wearable electronics, extending the application limits of flexible self-supported electrodes to ultralow-temperature conditions.