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 FeCl 3 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 FeCl 3 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 cm 2 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.