The structural evolution with alkali ion insertion, and the subsequent thermal evolution of the alkali-ion inserted ReO3 electrodes are shown by employing in situ and ex situ synchrotron X-ray diffraction (XRD). During Na and K insertion, there is a combination of intercalation into ReO3 and a two-phase reaction. Interestingly in the case of Li insertion, a more complex evolution is noted, which suggests a conversion reaction takes place at deep discharge (insertion). Following these ion insertion studies, extracted electrodes at various states of discharge (kinetically determined) were examined with variable temperature XRD. The thermal evolution of the Ax ReO3 phases, where A=Li, Na, or K, are significantly modified from the parent ReO3 thermal evolution. This shows the impact of alkali-ion insertion on the thermal properties of ReO3 .
Keywords: Electrochemical activation; phase evolution; structural transitions.
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