Silicon (Si)–carbon anode
with a continuous carbon
matrix
can alleviate the volume expansion of Si. However, most carbon precursors
need to be dissolved in organic solvents, which are toxic and expensive,
and the particulate electrode materials are easily exfoliated from
the current collector during cycling. Thus, it is highly desirable
to develop a new green strategy for enhancing the performance of Si–carbon
anodes. Here, we reported a low-cost and binder-free approach for
fabricating an integrated Si@C–Cu anode with fast electronic
transmission and excellent mechanical stability by employing a deep
eutectic solvent as a green solvent and combining the Si@C materials
with current collectors stably by generating strong Si–Cu bonds.
The experimental results show that Si nanoparticles uniformly embed
in the asphalt-derived carbon matrix to alleviate the volume expansion
of Si, and Cu3Si alloy is generated between Si@C composites
and Cu current collector which could significantly improve the electron
transport rate and electrical contact. Density functional theory simulation
demonstrates that the strong interaction between Cu and Si causes
a significant shift of the p-band center in Si, resulting in the continuity
of the total density of state at the Fermi level. Thus, the lithium-ion
battery (LIB) based on the Si@C–Cu anode displays a high initial
Coulombic efficiency of 84.8% and a specific capacitance of 2326 mAh
g–1 at 0.1 A g–1. Moreover, it
can deliver outstanding cycling stability by retaining 970 mAh g–1 after 200 cycles at 1 A g–1, which
was about 11 times higher than that of the Si@C anode. This work provides
a promising approach for application in high-performance Si/C anodes
of LIBs.