Self-confined synthesis of CoS1−x nanoparticles embedded in carbon nanosheets for lithium-ion batteries

Abstract

Rationally constructing metal sulfides-based anodes with high electronic conductivity, large electrode-electrolyte contact area, and multielectron conversion reaction is critically important for their application in lithium ion batteries. Cobalt sulfides are regarded as a promising anode material for lithium ion batteries owning to its high theoretical specific capacity and excellent redox reversibility, while the application of cobalt sulfides anode is hampered by the large volume expansion and the sluggish kinetic process. Herein, the cobalt sulfide (CoS1−x) nanoparticles embedded in the porous carbon nanosheets (CoS1−x@PCSs) was designed via a strategy of self-confined synthesis by using the prepared Co(OH)2 nanosheets and sodium citrate as the precursor. Such a self-confined synthesis strategy is significant to guarantee a good dispersion of CoS1−x nanoparticles and further confine the nanoparticles into carbon matrix. The rational 2D porous structure is engineered between CoS1−x nanoparticles and carbon nanosheets. As the conductive hosts, 2D porous structure can prevent the growth and offer sufficient space to buffer the volume expansion of CoS1−x nanoparticles. Besides, it also could provide abundant path for fast ion/electronic transport, while would reduce the length of diffusion channels, leading to improved electrochemical property. Benefiting from these advantages, the CoS1−x@PCSs electrode deliver a high reversible capacity of 1199.6mAhg−1 at 0.1 A g−1 after 100 cycles, outstanding rate performance (482.6mAhg−1 even at 5 A g−1), and long cycling stability with 825.7mAhg−1 achieved after 800 cycles at 1 A g−1, making the anode a promising candidate for lithium ion batteries.