Delithiation kinetics study of carbon coated and carbon free LiFePO4

A chemical oxidation method was employed to measure the kinetics of lithium release from LiFePO4 during oxidation. Similar to potential step measurements, the chemical method simplifies quantification compared to the common electrochemical techniques (PITT, GITT etc.). It was found that the overall release of lithium fits one dimensional diffusion kinetics, however, it is also shown that the mechanism must be more complex as the derived activation energy led to an unusually low attack rate of similar to 10(8) Hz. A comparison of carbon coated/carbon free LiFePO4 samples indicated that the carbon coating has only a marginal effect on the delithiation kinetics. (C) 2014 Published by Elsevier B.V.