M. Nishizawa et al., Measurements of chemical diffusion coefficient of lithium ion in graphitized mesocarbon microbeads using a microelectrode, EL SOLID ST, 1(1), 1998, pp. 10-12
The solid-state diffusion of lithium ion in carbon was directly investigate
d in single spherical particles of graphitized mesocarbon microbeads (MCMB,
Osaka Gas Co.). In order to achieve electrochemical measurements focusing
on a single particle, a molybdenum-filament microelectrode was maneuvered t
o make electrical contact with a single MCMB placed in an organic solvent m
ixture containing lithium ions as an electrolyte. This novel microelectrode
technique gives electrochemical information about a MCMB particle, itself,
without any dilution with additives such as organic binders. The chemical
diffusion coefficient (D) of lithium ion was determined from potential-step
chronoamperograms assuming spherical diffusion of lithium ions in the MCMB
particle. The values of D were found to change the order between 10(-9) an
d 10(-11) cm(2)/s depending on the electrode potential. Plots of D showed p
ronounced minima at the potentials where the transformation of staging leve
l of lithium intercalation compounds occurred. (C) 1998 The Electrochemical
Society, Inc. S1099-0062(98)01-019-0.