Characterization and Evaluation of Carbon Fibers as a Negative Electrode of Lithium Secondary Battery

Abstract

Lithium secondary battery using carbon as negative electrode, where Li is stored, has been developed. In the present paper, various kinds of carbon fibers with different macroscopic and crystallographic structure are applied a negative electrode for the lithium secondary batteries with 1molLiClO₄/propylene carbonate electrolyte. And the battery performances of the fibrous electrode are characterized and evaluated as a function of the structural features of the fibers. Li insertion mechanisms into carbon fiber negative electrode are classified into three groups from charge-discharge and the voltammetry measurements. The intercalation takes place in well-ordered graphite fibers, and the doping of Li occurs in the low crystalline, disordered, carbon fibers. Carbon fibers with intermediate crystalline structure indicate voltammograms between well-and disordered carbon fibers. Charge capacities of the fibrous anodes depend upon the crystallinity. Well-ordered and disordered carbon fiber electrodes exhibit larger capacity than those with intermediate crystallinity. It is evidently shown that the crystallinity of the fibrous carbon electrode is an important factor for desig of the cell performances in Li secondary battery.