Enhanced cycle stability of silicon nanoparticles coated with nitrogen-doped carbon layer for lithium-ion battery anode

We prepared single-crystal Si nanoparticles (Si NPs) ∼50 nm in diameter using a laser photopyrolysis technique and formed a nitrogen-doped carbon layer on them using pyrrole and FeCl3 to increase the cycle stability of the Si anodes during volume expansion and contraction. The surface chemical bonding states of the nitrogen-doped carbon-coated Si NPs were investigated. The specific capacity and capacity retention of the sample with 1 g of FeCl3 were the highest at approximately 967.1 mAh g−1 and 87.3% after 300 cycles at 1 C, respectively. The diffusion coefficient of Li ions after 1000 test cycles was 9.64 × 10−8 cm2 s-1. The higher cycling stability of the Si@NC NPs could be attributed to the nitrogen-doped carbon layers, which provided an efficient transport pathway for the electrons.