Design principles for high transition metal capacity in disordered rocksalt Li-ion cathodes
Author(s)Lun, Zhengyan; Ji, Huiwen; Balasubramanian, Mahalingam; Kwon, Deok-Hwang; Dai, Kehua; Lei, Teng; McCloskey, Bryan D.; Yang, Wanli; Kitchaev, Daniil Andreevich; Richards, William D; Clement, Raphaele Juliette; Papp, Joseph C; Lee, Jinhyuk; Ceder, Gerbrand; ... Show more Show less
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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.
DepartmentLincoln 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
Energy & Environmental Science
Royal Society of Chemistry (RSC)
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).
Final published version