화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.143, No.1, L4-L7, 1996
Improved Graphite Anode for Lithium-Ion Batteries - Chemically Bonded Solid-Electrolyte Interface and Nanochannel Formation
The effects of mild oxidation (burning) of two synthetic graphites on the reversible (Q(R)) and irreversible (Q(IR)) capacities, anode-degradation rate (on cycling) in three different electrolytes and graphite-surface topology have been studied. STM images of both modified graphites show nanochannels having an opening oi a few nanometers and up to tens of nanometers. It is believed that these nanochannels are formed at the zigzag and armchair faces between two adjacent crystallites and in the vicinity of defects and impurities. Mild burn-off was found to improve performance in Li/LixC cells : Q(R) is increased by 10-30%, Q(IR), is generally decreased (for less than 6% burn-off) and LixC6 anode degradation rate is much lower. Performance improvement is attributed to the formation of SEl chemically bonded to the surface carboxylic groups at the zigzag and armchair faces, and to accommodation of extra lithium at the zigzag, armchair, and other edge sites and nanovoids.