Si-based Composite Anode for Li-ion Batteries with Enhanced Electrochemical Performance via CuCl2·2H2O Assisted Coating of PDA

Silicon (Si) is a promising anode material for Li-ion batteries but its application is limited due to its low electronic conductivity and severe volume change during the lithiation/delithiation process. Recently, coating a carbon layer on the Si surface and doping the alloy phase into the bulk Si have been considered as effective approaches to resolve the aforementioned issues. The present study proposes a facile method via coating the polydopamine (PDA) with the assistance of CuCl2·2H2O followed by a high-temperature annealing process to successfully fabricate the Si-based anode material with a unique structure of Si-Cu3Si@C. Owing to the synergistic effect of carbonized PDA layer and doped Cu3Si phase, both structural stability and electronic conductivity of electrode have been significantly enhanced. The Si-Cu3Si@C composite anode not only exhibited a high initial reversible capacity of 1.44 mAh·cm-2 (2483 mAh·g-1) with an initial coulombic efficiency of 83.2%, but also demonstrated a good capacity retention of 91.3% after 100 cycles at the current density of 0.28 mA·cm-2 (480 mA·g-1). In particular, an excellent reversible capacity of 0.75 mAh·cm-2 (1339 mAh·g-1) after a long-term test of 400 cycles was displayed at the high current density of 1.4 mA·cm-2 (2500 mA·g-1).