In-situ preparation and excellent performance of Co9S8/C/NF with binder-free as anodes for lithium-ion batteries

Nowadays, developing new anode material for lithium-ion batteries (LIBs) with distinguished electrochemical properties is still very significant and a huge challenge. Herein, a nanocomposite containing Co9S8/carbon (C)/nickel foam (NF) was synthesized. In the preparation process, ZIF-67 as the source of both Co2+ and carbon was designedly grown in situ on the surface of NF with loose porous skeleton through the hydrothermal reaction. After sulfurization and pyrolysis of ZIF-67/NF, the porous flower-like Co9S8/C/NF composites formed. As a binder-free anode, Co9S8/C/NF exhibited excellent lithium storage performance, which showed a superior initial discharge capacity of 1926 mA h g−1 and reversible capacity of 1114 mA h g−1 after 200 cycles at 0.2 A g−1. Even at 2 A g−1 current density, it could maintain a capacity of 578 mA h g−1. The above outstanding electrochemical performances may be due to the following reasons. The loose flower-like structure assembled by lots of nanosheets, can provide a larger surface area for the transport and storage of Li+ ions. With the cooperation of carbon matrix, the volume expansion of anodes can be effectively alleviated during charge and discharge process. At the same time, metal nickel foam as the current collector of the negative electrode also can increase the conductivity; promote the transport and diffusion of electrons. The loose skeleton enables the full contact of the active material with the electrolyte, which is beneficial to the transportation of Li+ ions and electronics. This work provides an inspiration for designing and fabricating anode materials with distinguished-performance for LIBs.