Highly durable SiOC composite anode prepared by electrodeposition for lithium secondary batteries

A highly durable SiOC composite anode was prepared for use in lithium secondary batteries. The SiOC composite was synthesized by electrodeposition of SiCl₄. The composite anode delivered a discharge capacity of 1045 mA h per gram of Si at the 2000^th cycle and 842 mA h per gram of Si even at the 7200^th cycle. The reason for the excellent cyclability was investigated by methods including field emission scanning electron microscopy (FESEM), scanning transmission electron microscopy with an energy dispersive X-ray analyser (STEM-EDX), and X-ray photoelectron spectroscopy (XPS). The results revealed that the excellent cyclability was achieved by the homogeneous dispersion of SiO_x and organic/inorganic compounds at the nanometre scale. The structural uniformity of the SiOC composite is believed to have suppressed the crack formation attributable to the stress resulting from the reaction of silicon with lithium during charge-discharge cycles.