Carbon Free Si Electrode Based on Micron Size Si Particles for Advanced Lithium Ion Rechargeable Battery

Abstract

Silicon (Si) is an attractive candidate for lithium-ion batteries because it delivers 10 times greater theoretical (∼4200 mAh/g) specific capacity than that of a traditional graphite anode (∼370 mAh/g). However, the widespread application of silicon materials has remained a significant challenge because of the large volume changes during lithium insertion and extraction processes, particularly when using bulk or micrometer-sized silicon particles. This large volume change causes cracking and pulverization of silicon, which leads to loss of the electrical contact and drastic capacity fading. To address the significant challenges associated with large volume change of micrometer-sized Si particles as high-capacity anode materials for lithium-ion batteries, we demonstrated a simple but effective strategy: using Si nanoparticles as a structural and conductive additive, with micrometer-sized Si as the main lithium-ion storage material. The Si nanoparticles connected into the network structure in situ during the charge process, to provide electronic connectivity and structure stability for the electrode. The resulting electrode showed a high specific capacity of 2500 mAh/g after 30 cycles with high initial Coulombic efficiency (73%) and good rate performance during electrochemical lithiation and delithiation: between 0.01 and 1 V vs Li/Li+.