Synthesis and characterization of newly identified Si3-xMxN4 (M= Co, Fe) anodes for lithium batteries

摘要

A novel category Si3N4 anode and a series of doped derivatives of silicon nitride with a general formula Si3-xMxN4 [M= Co and Fe] were identified as possible anode materials for rechargeable lithium batteries through the present study. The compounds were synthesized via solid-state fusion method and characterized for phase purity and surface morphology through XRD and SEM respectively, prior to electrochemical Performance analysis. The compound Si3N4 exhibited inferior capacity (similar to 100mAh/g) whereas the metal doped nitrides, viz., Si3-xMxN4 [M= Co and Fe] exhibited improved. specific capacity values in the range of 130-470 mAh/g, with lesser capacity fade (<20%) after 50 cycles. More specifically, the Si3-xFexN4 anode with a specific capacity of similar to 470mAh/g may be exploited for practical applications. The effects of individual dopants in enhancing the electrochemical behavior Si3-xMxN4 anodes are discussed.