Design principles for high transition metal capacity in disordered rocksalt Li-ion cathodes
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Author(s)
Lun, Zhengyan
Ji, Huiwen
Balasubramanian, Mahalingam
Kwon, Deok-Hwang
Dai, Kehua
Lei, Teng
McCloskey, Bryan D.
Yang, Wanli
Kitchaev, Daniil Andreevich
Clement, Raphaele Juliette
Date Issued
July 12, 2018
Journal
Energy & Environmental Science
Publisher
Royal Society of Chemistry (RSC)
Citation
Kitchaev, Daniil A., Zhengyan Lun, William D. Richards, Huiwen Ji, Raphaële J. Clément, Mahalingam Balasubramanian, Deok-Hwang Kwon, et al. “Design Principles for High Transition Metal Capacity in Disordered Rocksalt Li-Ion Cathodes.” Energy & Environmental Science (2018).
Version
Final published version
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.
MIT Department
Lincoln Laboratory
Massachusetts Institute of Technology. Department of Chemistry
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
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DOI of Published Version
https://doi.org/10.1039/C8EE00816G
