Analysis of Mechanical Properties and Electrochemical Behavior of Li-Ion Secondary Batteries According to Particle Size of Silicon Anode

Abstract

Li-ion secondary batteries have been applied to various electronic devices since Sony released a lithium secondary battery using hard carbon as an anode in 1991. The market for large secondary batteries is gradually expanding and moving forward. And although high energy density, cyclability, and stability are required for use in various applications at this time, the currently commercialized graphite anode is facing the limit of theoretical capacity (LiC6, 372 mAh/g).While research on next-generation anode materials is underway to increase the energy density of lithium secondary batteries, silicon has a high theoretical capacity close to 4000 mAh/g, attracting attention as an anode for next-generation lithium-ion batteries. However, the capacity retention rate is low due to the huge volume change and low electrical conductivity that occur during charging and discharging of silicon.In order to solve this problem, many studies are being conducted, such as a) making a silicon-sized structure into a nano-scale and porous structure, b) oxidizing silicon, and c) a composite with a carbon material. Among them, much attention has been paid to improving the electrochemical performance of a silicon-based anode by designing a structure by fabricating silicon in a nano size. Compared to conventional silicon materials, nano-sized silicon was able to better withstand the stress caused by volume expansion during charging/discharging in the nano-surface-to-volume ratio. As a result, intergranular cracking can be limited, thereby improving cycle stability and maintaining high capacity. The particles can shorten the diffusion path of lithium by providing a stable electron and Li-ion transport path, and can provide increased rate-limiting properties and reduced resistance.In this study, the effect of the manufactured silicon grain size on the mechanical and electrochemical properties of the Li-ion secondary battery was studied by various analytical methods.