Abstract
A flexible and free-standing anode that consists of flower-like copper sulfide (CuS), metal copper (Cu) nanoparticles and multi-walled carbon nanotubes (CNTs) is synthesized by a facile electroplating-vulcanization method. The nano-micro flower shaped CuS particles, distributed uniformly on the surface of flexible Cu@CNTs membrane, are formed by many interconnected 10 nm thick sheets. This unique structure promises fast Na+ diffusion. The CNTs and those Cu particles confined into the CNTs network provide a highly conductive matrix for electrons. Moreover, adding binders are not required since the active particles are already closely bound to the matrix. The binder-free CuS-Cu@CNTs anode exhibits superior rate performance (439.9 mAh g−1 at 3.2 A g−1) and excellent long-term cycle stability (512.5 mAh g−1 after 1100 cycles at 2.4 A g−1) at room temperature. At −20 °C, a high capacity of 413.6 mA h g−1 can still be obtained at 100 mA g−1. The performance improvement and energy storing mechanism are investigated with galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and ex-situ XRD.
Published Version
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