Tubular-like Nanocomposites with Embedded Cu 9 S 5 -MoS x Crystalline-Amorphous Heterostructure in N-Doped Carbon as Li-Ion Batteries Anode toward Ultralong Cycling Stability.

Transition metal sulfides (TMSs) show the potential to be competitive candidates as next-generation anode materials for Li-ion batteries (LIBs) due to their high theoretical specific capacity. However, sluggish ionic/electronic transportation and huge volume change upon lithiation/delithiation remain major challenges in developing practical TMS anodes. We rationally combine structural design and interface engineering to fabricate a tubular-like nanocomposite with embedded crystalline Cu 9 S5 nanoparticles and amorphous MoS x in a carbon matrix (C/Cu 9 S 5 -MoS x NTs). On the one hand, the hybrid integrated the advantages of 1D hollow nanostructures and carbonaceous materials, whose high surface-to-volume ratios, inner void, flexibility, and high electronic conductivity not only enhance ion/electron transfer kinetics but also effectively buffer the volume changes of metal sulfides during charge/discharge. On the other hand, the formation of crystalline-amorphous heterostructures between Cu 9 S 5 and MoS x could further boost charge transfer due to an induced built-in electric field at the interface and the presence of a long-range disorder phase. In addition, amorphous MoS x offers an extra elastic buffer layer to release the fracture risk of Cu 9 S 5 crystalline nanoparticles during repetitive electrochemical reactions. Benefiting from the above synergistic effect, the C/Cu 9 S 5 -MoS x electrode as an LIB anode in an ether-based electrolyte achieves a high-rate capability (445 mAh g -1 at 6 A g -1 ) and superior ultralong-term cycling stability, which delivers an initial discharge capacity of 561 mAh g -1 at 2 A g -1 and its retention capacity after 3600 cycles (376 mAh g -1 ) remains higher than that of commercial graphite (372 mAh g -1 ).