Design principles for high transition metal capacity in disordered rocksalt Li-ion cathodes
Date Published |
05/2018
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Publication Type | Journal Article
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Authors | |
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DOI |
10.1039/c8ee00816g
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Abstract |
The discovery of facile Li transport in disordered, Li-excess rocksalt materials has opened a vast new chemical space for the development of high energy density, low cost Li-ion cathodes. We develop a strategy for obtaining optimized compositions within this class of materials, exhibiting high capacity and energy density as well as good reversibility, by using a combination of low-valence transition metal redox and a high-valence redox active charge compensator, as well as fluorine substitution for oxygen. Furthermore, we identify a new constraint on high-performance compositions by demonstrating the necessity of excess Li capacity as a means of counteracting high-voltage tetrahedral Li formation, Li-binding by fluorine and the associated irreversibility. Specifically, we demonstrate that 10–12% of Li capacity is lost due to tetrahedral Li formation, and 0.4–0.8 Li per F dopant is made inaccessible at moderate voltages due to Li–F binding. We demonstrate the success of this strategy by realizing a series of high-performance disordered oxyfluoride cathode materials based on Mn2+/4+ and V4+/5+ redox. |
Journal |
Energy & Environmental Science
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Volume |
11
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Year of Publication |
2018
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Issue |
8
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Pagination |
2159 - 2171
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ISSN Number |
1754-5692
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Short Title |
Energy Environ. Sci.
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Refereed Designation |
Refereed
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Organizations | |
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