The capacity intermittent titration technique was used to investigate the chemical

diffusion coefficient, D, of lithium ions in LiFePO4 cathode material. The values of

D at a galvano-charge current of 0.2 and 0.4mA were found to range from 8.8 x

10−16 to 8.9 x 10−14cm2/s and from 1.2 x 10−16 to 8.5 x 10−14cm2/s, respectively, in

the range of 3.2 to 4V (vs. Li+/Li). The transfer coefficients of cathode (0.32–0.42)

and anodic (0.26–0.3), and the standard rate constant (1.58 x 10−9 to 1.30 x

10−8cm/s) were measured from the Tafel plots of LiFePO4 in the equilibrium

potential range from 3.06 to 3.45V. From these kinetic parameters, the finite

kinetics at interface was taken into account to revise the above values of D. The

revised values of D at the galvano-charge current of 0.2 and 0.4mA were

respectively found to range from 2.44 x 10−15 to 2.21 x 10−13cm2/s and from 5.81 x

10−16 to 3.22 x 10−13cm2/s in the voltage range from 3.2 to 4V. Results showed that

the approximation of infinite charge-transfer kinetics leads to a spurious value of D

which was lower than the revised value, and the spurious extent depended upon the

galvano-charge current of capacity intermittent titration experiments.

Investigation on Diffusion Behaviour of Li+ in LiFePO4 by Capacity Intermittent

Titration Technique (CITT). X.C.Tang, L.X.Li, Q.L.Lai, X.W.Song, L.H.Jiang:

Electrochimica Acta, 2009, 54[8], 2329-34