Si(Co)(Y) Negative Electrodes For Li-Ion Batteries

Si(CO)(y) (0 <= y <= 0.43) alloys were synthesized by reactive gas milling silicon in CO2 at room temperature. Silicon reacts with CO2 rapidly during milling, incorporating C and O in a 1:1 ratio to form alloys consisting of Si nanograins dispersed in an amorphous Si-O-C matrix. The capacity behavior of these alloys suggests the formation of inactive SiC and Li4SiO4 during the first lithiation. This implies that such alloys can have significantly greater initial coulombic efficiency (ICE) than SiOx at any given gravimetric or volumetric capacity.