Cu3Si enhanced crystallinity and dopamine derived nitrogen doping into carbon coated micron-sized Si/Cu3Si as anode material in lithium-ion batteries

•Dopamine self-assemble on irregularly sub-micron sized Si/Cu3Si aggregates.•Self-assembled dopamine further to form sheet-like carbon framework after pyrolysis.•Dispersed Cu3Si as catalyst induced CCVD, enhances carbon shell crystallinity.•Cu3Si reinforced nitrogen doping into carbon shell. A chemical vapor decomposition (CVD) enhanced carbon coated Si/Cu3Si composite aggregate (C-Si/Cu3Si@C) is prepared as anode material to alleviate volume expansion and improve the electrochemical performance for lithium-ion batteries (LIBs). In this work, micron-sized C-Si/Cu3Si@C is fabricated through self-assembling of dopamine as first carbon precursor on irregularly shaped and sub-micron-sized Si/Cu3Si composite, followed by CVD with ethylene (C2H4) as second carbon precursor. Besides, dopamine not only self-assembles on the surface of Si/Cu3Si composite but also grows into sheet-like film that supports and connects Si/Cu3Si composite into micron-sized aggregate. In addition to CVD, Cu3Si induces catalytic chemical vapor deposition (CCVD), which enhances integrality of the carbon shell as well as reinforce nitrogen doping into carbon shell to enhance conductivity. Therefore, the C-Si/Cu3Si@C composite performs in optimum condition when the cycle is stable, attaining delithiation capacity of 2101 mAh g−1, coulombic efficiency of 84.7% for the 1st cycle and achieves capacity retention of 82.9% after 100 cycles. [Display omitted]