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• Cu 7 S 4 nanocrystals fixed on the carbon nanotube film, directly for electrodes. • The phase change of Cu 7 S 4 during the electrochemical process has been studied. • GITT is executed to investigate the reaction kinetics. Sodium-ion batteries (SIBs) have been identified as capable alternatives with great promise to lithium-ion batteries (LIBs) on account of affordable cost and satisfactory natural abundance of metallic sodium. However, they may suffer volume expansion of the active material and eventually the disintegration of the microstructure during the process of charge and discharge, giving rise to inferior reversible capacity and poor cyclic stability. In this work, we germinate nanoscale Cu 7 S 4 on the carbon nanotube film innovatively by hydrothermal, which may be the first time Cu 7 S 4 has been grown on such a thin film interwoven with innumerable carbon nanotubes and apply to the anode of SIBs to the best of our knowledge. The freestanding composite electrode without any binder and conductive auxiliary retains 553 mA h g−1 after 300 cycles at 1A g−1. Furthermore, ex situ characterization is employed to make a thorough inquiry of phase transitions and the relationship with the kinetics of Na-ion diffusion by the combination with galvanostatic intermittent titration technique (GITT) in the whole electrochemical process. We anticipate our work can provide a promising scheme for the research of the energy supply system of flexible wearable devices. [ABSTRACT FROM AUTHOR]

• FSPCMs with excellent heat-resistance and high enthalpy were fabricated. • Polyamide 6 based PCFs have been successfully produced by melt spinning process. • PCFs presented a long thermal management time and superior washing durability. Phase change materials (PCMs) have attracted considerable attention due to their superior function for energy storage and temperature regulation and its promising applications in fibers. However, PCMs prepared by conventional strategies always suffer a poor heat resistance, making them infeasible for melt-spun fibers. We present here a nano-hybridized form-stable phase change materials (FSPCMs) via a molecular chain structural selection strategy and nano-hybridization technique; featuring with high heat resistant and hydrophobicity, such FSPCMs can be applied for the melt spinning of polyamide 6 (PA6)-based phase change fibers (PCFs). The organic-inorganic nano-hybridized FSPCMs presents a transformation from solid-liquid phase transition to solid-solid phase transition with improved thermal response rates. And, an optimized FSPCM not only preserves a high enthalpy (137 J/g) and heat resistance temperature (up to 328.5 °C) but also display a superior phase change stability after simulated thermal cycling over 200 times; meanwhile, it can efficiently delay its micro-environmental temperature change for up to 1182 s with an outstanding energy storage and temperature regulation function. More importantly, incorporating FSPCMs into the melt-spun PA6, the resultant PCFs also demonstrate a smart regulation on its micro-environmental temperature for 786 s with an enthalpy of 9.44 J/g. In addition, the functions of such PCFs also present a good washing durability; which can withstand a practical washing for 1 h at different temperatures (0 °C, 25 °C, and 90 °C). [ABSTRACT FROM AUTHOR]