Multi-electron cathode materials for Li-ion batteries bypass the restrictions imposed by conventional intercalation chemistries limited to 1 e– for each transition metal. Li-rich phases like the Li2MO3 phases studied by Goodenough and later Tarascon support oxidation of &gt;1 e– per transition metal, bypassing the paradigm imposed by conventional intercalation chemistry. In the oxide phases, the oxidation profile changes significantly from the first to second cycle suggesting issues with reversibility. In an effort to develop structure-property relationships associated with multi-electron redox, we have prepared structurally analogous alkali-rich sulfide phases. The sulfides phases benefit from a lower voltage window thereby eliminating detrimental electrolyte decomposition that obfuscates the electrochemistry. Sulfides also allow us to probe the behavior of technologically relevant 3d transition metals. We will discuss the redox mechanisms associated with the sulfide phases from a structural point of view and the differences in reversibility compared to the oxides.

Multi-electron redox in alkali-rich sulfides

2019 Fall National Meeting

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