Electrochemical properties of heat-treated polymer-derived SiCN anode for lithium ion batteries

Silicon-carbon-nitrogen material (SiCN) is pyrolyzed from polysilylethylenediamine (PSEDA) derivation, followed by a heat-treating process at 1000 °C in Ar atmosphere. This heat-treated SiCN material has an excellent electrochemical performance as an anode for lithium ion batteries. Charge-discharge cycle measurements show that the heat-treated SiCN material exhibits a high first cycle discharge capacity of 829.0 mAh g⁻¹ and stays between 400 and 370 mAh g⁻¹ after 30 cycles. The discharge capacity remains above 300 mAh g⁻¹ at the high current density of 80 and 160 mA g⁻¹. These values are higher than untreated SiCN and commercial graphite anodes, which indicates that the heat-treating process improves the charge-discharge capacity, cycle stability and high-rate ability of SiCN anode. It is seemed that changes of SiCN structure, the formation of loose nano-holes on material surface and the formation of graphitic carbon phase in heat-treating process contribute to the improvement of electrochemical properties for SiCN anode.