Shape-controlled silicon particles for high-capacity negative electrode of Li-ion batteries

Abstract

Pure Si platelets (Si-LP, thickness: 100 nm) and Ni layer-laminated Si platelets with different thicknesses (Si/Ni/SiLP50 (50/50/50 nm) and Si/Ni/Si-LP30 (30/30/30 nm)) were prepared by a vapor deposition method, and their charge/discharge properties were investigated as alternative negative electrode materials to graphite for lithiumion batteries. The shape of thin platelet effectively relieved the stress during the alloying and de-alloying processes, and improved the charge/discharge cycleability as compared with a commercially available Si powder. In particular, the laminated platelet samples showed very good cycleability, probably because of a shorter diffusion length of Li+ ions in the Si layers and an improved mechanical strength by the presence of the Ni layer.