In Situ Synthesis of Multilayer Carbon Matrix Decorated with Copper Particles: Enhancing the Performance of Si as Anode for Li-Ion Batteries

A 3D structured composite was designed to improve the conductivity and to ease the volume problems of Si anode during cycling for lithium-ions batteries. An in situ method via a controllable gelation process was explored to fabricate the 3D composite of a multilayer carbon matrix toughened by cross-linked carbon nanotubes (CNTs) and decorated with conductive Cu agents. Structurally, a bifunctional carbon shell was formed on the surface of Si to improve the conductivity but alleviate side reactions. Cu particles as conducting agents decorated in the carbon matrix are also used to further improve the conductivity. The volume issue of Si particles can be effectively released via toughening the carbon matrix through the multilayered structure and cross-linked CNTs. Moreover, the carbon matrix might prevent silicon particles from agglomeration. Consequently, the Si@C@Cu composite is expected to exhibit benign electrochemical performances with a commendable capacity of 1500 mAh g ^-1 (900 cycles, 1 A g ^-1 ) and a high rate performance (1035 mAh g ^-1 , 4 A g ^-1 ). The D _Li ⁺ ranging from 10 ^-11 to 10 ^-9 cm ^-2 s ^-1 of the Si@C@Cu anode is obtained via the GITT test, which is higher than most reported data.