Flexible WS2@CNFs Membrane Electrode with Outstanding Lithium Storage Performance Derived from Capacitive Behavior

Flexible electrodes have recently elicited attention due to their potential to be woven into textiles as flexible power supplies for wearable electronic devices. However, contemporary flexible electrodes generally suffer from the limited reaction kinetics and inferior stability. Here, a flexible WS2@CNFs membrane electrode is facilely fabricated via hydrothermal method and subsequent electrospinning to embed WS2 nanosheets into interconnected framework of carbon nanofibers (CNFs). Benefitting from 3D porous architecture and good conductivity of CNFs, WS2@CNFs composites exhibit outstanding cycling stability and rate capability as self-supported binder-free anode for lithium-ion batteries. Especially, WS2@CNFs with 60.3 wt% of WS2 displays a discharge specific capacity as high as 545 mA h g(-1) at 0.5 A g(-1) after 800 cycles. Even at 2 A g(-1), it maintains 62.4% of specific capacity at 0.1 A g(-1), and stably cycles back at 0.1 A g(-1). Kinetic analysis confirms that the capacitive mechanism is dominant in the Li-ion storage process, which is derived mainly from the structure evolution from WS2 nanosheets to WS2/W nanoparticles during extended cycling. The reduced nanoparticles also enhance electrochemical activity, conductivity, and reversibility of the conversion reaction, resulting in the increasing capacity with cycles.