Electrochemistry of Catalytically Graphitized Ball Milled Carbon in Li Batteries

Abstract

High carbon Fe-C composites with starting concentrations of 10, 20, 30, and 40 wt% Fe (2.3 - 12.5 atomic % Fe) were prepared by ball milling followed by annealing. Increasing the Fe concentration and annealing temperature resulted in catalytic graphitization of the carbon. Mössbauer spectroscopy analysis indicated that Fe concentration and annealing temperature had significant effects on the Fe magnetic hyperfine field, quadrupole splitting, and the formation of γ-Fe. When used as electrodes in Li cells, the electrochemistry of ball milled Fe-C powders annealed at low temperatures resembled that of amorphous carbon. Fe-C with 40 wt% Fe annealed at 2000°C had electrochemical characteristics of a pristine graphite electrode with good cycling performance. These results demonstrate that lithium battery negative electrodes with good cycling performance can be produced from catalytically prepared graphite.