In-situ embedding cobalt-doped copper sulfide within ultrathin carbon nanosheets for superior lithium storage performance

Abstract

Construction of well-defined hybrid composites consisting of transition metal sulfides and two-dimensional (2D) carbon nanosheets as high-performance anodes for lithium-ion batteries (LIBs) is of great significance but remains challenging. Herein, we have developed a novel strategy to in-situ fabricate a nanohybrid composites consisting of cobalt-doped copper sulfides nanoparticles embedded in 2D carbon nanosheets (2D Co-Cu2S@C) through a one-pot sulfurization of 2D nanosheet-like Co-doped copper-based metal-organic frameworks (MOFs) precursors. When applied as LIBs anodes, the as-prepared 2D Co-Cu2S@C composites could deliver a specific capacity of 780 mAh g−1 at 0.5 A g−1 after 300 cycles and a high-rate capability with 209 mAh g−1 at 5 A g−1, superior to most reported copper sulfide-based anodes. The exceptional performance could be attributed to the synergism of ultrathin structure (~4 nm), appropriate cobalt doping and strong carbon coupling, resulting in the shortened paths for Li+ transportation, enlarged exposing surface for Li+ adsorption, enhanced electric conductivity for charge transfer as well as robust mechanical property against volume expansion.