Synthesis of passively prelithiated SiOx nanoparticles for Li-ion battery anode

A new concept of passive prelithiation to SiO_x nanoparticles is introduced and evaluated by investigating their nanostructures and electrochemical properties. Specifically, Li is incorporated into SiO_x nanoparticles during the nanoparticle synthesis. We obtain Si-Li-O-based nanoparticles, which we call SILIO; these are much larger than SiO_x particles and have totally different nanostructures. Due to nanostructures with various phase distributions, SILIO nanoparticles show enhanced electrochemical properties. The initial reversible capacity (IRC) and initial columbic efficiency (ICE) of SILIO nanoparticles are 946 to 1107 mAh/g and 72% to 77%, respectively, while SiO_x exhibits 1,064 mAh/g of IRC only with 41.5% of ICE. In addition, the stability of SILIO in the air is evaluated to guarantee no unstable phases such as Li₂O_x (x = 0–2) are present in SILIO. Through our findings, we suggest a new nanostructure model composed of crystalline Si, amorphous SiO_x, and lithium silicate.