고 용량 장 수명 리튬 이차전지용 탄소-규소 복합체 음극의 전기화학특성 향상에 대한 연구

Abstract

Nano-structured Si/C composites were synthesized by means of high energy ball milling and mixing with pitch-based carbon at various weight fractions to reduce the crystallization of silicon and to improve cycle stability. The structure, morphology and surface area values of Si/C composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) measurements. Moreover, the composition ratio and heat treatment temperature of Si/C composites were studied by thermogravimetric analysis (TGA) and elemental analyzer (EA). The electrochemical performance of Si/C composites was investigated by cyclic voltammetry (CV), galvanostatic cycling, and rate performance. From these results, we confirmed that the optimized high energy ball milling time for the Si/C composite was 10 hours. The Si/C composites (Si 30 to 50 wt. %) have a specific capacity range from 590 to 860 mAh g-1 a good cycle performance in a voltage of 0.01-1.5 V at a current density of 60 mA g-1 (0.1 C-rate) over 50 cycles. The Si(30 wt. %)/C composite showed excellent rate performance from 0.1 C (60 mA g-1) to 30 C (18 Ah g-1).