Nano-porous SiO/carbon composite anode for lithium-ion batteries

Carbon-coating of sub-mu m SiO particles (d(max) = 0.36 mu m, d(50) = 0.69 mu m) by a fluidized-bed chemical-vapor-deposition process has produced unique nano-porous SiO/C secondary particles within which the SiO primary particles are "glued" together by carbon to form a network that possesses randomly distributed pores with sizes in the nano-meter range and a bulk porosity of > 30%. Upon lithiation/delithiation cycling in an organic Li-ion electrolyte, the electrode made of the SiO/C particles exhibited reduced polarization, smaller irreversible electrode expansion, and remarkably enhanced cycling performance, as compared with that of pristine SiO particles. The reduced electrode expansion exhibited by the SiO/C electrode can be attributed to the combination of diluted SiO content and presence of pre-set voids, which could partially accommodate volume expansion arising from lithiation of the SiO primary particles. These effects render the SiO/C electrode structurally more robust than the SiO electrode against volumetric variations upon cycling.