Kinetic study of LiMn2O4 cathodes by in situ XRD with constant-current cycling and potential stepping

The structure and kinetics of LiMn2O4 electrodes have been investigated by in situ X-ray diffraction (XRD) measurements using a novel three-electrode in situ XRD cell, where the reference electrode is sited on the reverse side of the working electrode to facilitate accurate determination of the electrode potential. The use of ballmilling during electrode preparation resulted in a high level of utilization at high charge/discharge rates of LiMn2O4-based electrodes in both structural and electrochemical studies. No evidence of Li concentration gradients in the solid material could be observed from XRD, thus excluding solid-phase diffusion and also phase boundary movement, as described by Fick's law, as the rate-limiting step. (C) 2002 The Electrochemical Society.