Differences in size and electropositivity among Li, Na and Mg can lead to very different electrochemical, thermodynamic and transport behavior when these cations intercalate into transition metal oxides and sulfides that have a layered or spinel crystal structure. We have performed a systematic first-principles and statistical mechanics study to unravel the electronic and atomic scale factors that underlie these differences. The large size of Na makes layered intercalation compounds susceptible to numerous phase transformations involving a change in stacking sequence. Na intercalation compounds are also more prone to order-disorder phenomena. While Li and Mg have similar sizes, their difference in valence state leads to important differences in site preference, especially in spinel hosts. The size of the intercalating specie can also have an effect on Jahn-Teller distortions around the transition metal. Statistical mechanics studies shed light on the behavior of Jahn-Teller distortions at elevated temperature or in the presence of cation disorder. These studies enable the formulation of design principles that guide the development of superior electrode materials.  <br/>

Differences and similarities between Li, Na and Mg intercalation in transition metal oxides and sulfides

255th National Meeting (2018)

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