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

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-CuS@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-CuS@C composites could deliver a specific capacity of 780 mAh g at 0.5 A g after 300 cycles and a high-rate capability with 209 mAh g at 5 A g, 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.