CoS Nanosheets Coated with Dopamine-Derived Carbon Standing on Carbon Fiber Cloth as Binder-Free Anode for Li-ion Batteries

Abstract

Cobalt sulphides attract much attention as anode materials for Li-ion batteries (LIBs). However, its poor conductivity, low initial column efficiency and large volume changes during cycling have hindered its further development. Herein, novel interlaced CoS nanosheets were firstly prepared on Carbon Fiber Cloth (CFC) by two hydrothermal reactions followed with carbon coating via carbonizing dopamine (CoS NS@C/CFC). As a freestanding anode, the nanosheet structure of CoS not only accommodates the volume variation, but also provides a large interface area to proceed the charge transfer reaction. In addition, CFC works as both a three-dimensional skeleton and an active substance which can further improve the areal capacity of the resulting electrode. Furthermore, the coated carbon combined with the CFC work as a 3D conductive network to facilitate the electron conduction. The obtained CoS NS@C/CFC, and the contrast sample prepared with the same procedure but without carbon coating (CoS NS/CFC), are characterized with XRD, SEM, TEM, XPS and electrochemical measurements. The results show that the CoS NS@C/CFC possesses much improved electrochemical performance due to the synergistic effect of nanosheet CoS, the coated carbon and the CFC substrate, exhibiting high initial columbic efficiency (~87%), high areal capacity (2.5 at 0.15 mA cm −2 ), excellent rate performance (1.6 at 2.73 mA cm −2 ) and improved cycle stability (87.5% capacity retention after 300 cycles). This work may provide a new route to explore freestanding anodes with high areal specific capacity for LIBs.