Diffusion coefficient of lithium in artificial graphite, mesocarbon microbeads, and disordered carbon

Abstract

The structures of pyrolytic sugar carbon, resin carbon, artificial graphite and mesocarbon microbeads (MCMBs), and the diffusion coefficient of lithium in them were determined by X-ray diffraction and potential step chronoamperometry measurements. It was found that the diffusion coefficient of lithium was strongly dependent on the degree of discharge and the structure of the carbon an-odes. As the discharge degree increased, the diffusion coefficient of lithium in MCMB anodes decreased from 4.43×10-9 cm 2/s to 5.24×10 −10 cm 2/s. At half discharge, the diffusion coefficients of lithium in sugar carbon, resin carbon, artificial graphite, and MCMB anode were 1.4×10 −10 cm 2/s, 5.75×10 −10 cm 2/s, 1.24×10 −9 cm 2/s, 2.1×10 −9 cm 2/s, respectively, showing that diffusion of lithium in soft carbons (artificial graphite and MCMBs) was much easier than that in hard carbons such as sugar and resin carbon.