Rate-Induced Solubility and Suppression of the First-Order
Phase Transition in Olivine LiFePO<sub>4</sub>
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Abstract
The
impact of ultrahigh (dis)charge rates on the phase transition
mechanism in LiFePO<sub>4</sub> Li-ion electrodes is revealed by in
situ synchrotron diffraction. At high rates the solubility limits
in both phases increase dramatically, causing a fraction of the electrode
to bypass the first-order phase transition. The small transforming
fraction demonstrates that nucleation rates are consequently not limiting
the transformation rate. In combination with the small fraction of
the electrode that transforms at high rates, this indicates that higher
performances may be achieved by further optimizing the ionic/electronic
transport in LiFePO<sub>4</sub> electrodes