Study of nanostructured silicon anode prepared by magnesiothermic reduction of diatomite for lithium-ion batteries

by Hayeon Won (MS Candidate)

Thursday Nov 14, 2013, 2:50 PM → 3:20 PM Asia/Seoul

119호Haye (제1과학관)

Nanostructured silicon anode was prepared by magnesiothermic reduction of diatomite for high capacity rechargeable lithium ion batteries (LIBs). Suitable reduction condition were found out to be at 700°C for 3 hours with Mg : D iatomite = 2 : 1. To remove the by-products and obtain pure nanostructured silicon, the resultant was treated with a hydrochloric acid (HCl) and hydroflu oric acid (HF). The nanostructured silicon obtained from diatomite showed sp onge morphology. The CR2032 type coin cell was assembled to study electro chemical properties of obtained materials.
The CR2032 type coin cell is composed of a lithium metal disk as a counte r electrode, nanostructured silicon as a working electrode, polypropylene mem brane as separator, and 1 M of LiPF6 in a 1:1:1 v/v mixture of ethylene car bonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC) as elect rolyte to study of electrochemical properties of obtained materials.
The SEI layer was formed at 0.69 V on the anode surface and the Li+ ions was inserted into silicon at 0.17 V during lithiation process. The inserted Li+ ions are extracted from silicon at 0.38 V and 0.52 V during delithiation. The fabricated silicon anode has an average capacity of 1687 mAh/g which is 2.4 and 4.8 times higher than that of commercial silicon anode and theoretical capacity of graphite anode, respectively.

Thesis Advisor: Prof. Dohyung Kim