Abstract
Mn-based Li-excess cation-disordered rocksalt (DRX) oxyfluorides are promising candidates for next-generation rechargeable battery cathodes owing to their large energy densities, the earth abundance, and low cost of Mn. In this work, we synthesized and electrochemically tested four representative compositions in the Li-Mn-O-F DRX chemical space with various Li and F content. While all compositions achieve higher than 200 mAh g−1 initial capacity and good cyclability, we show that the Li-site distribution plays a more important role than the metal-redox capacity in determining the initial capacity, whereas the metal-redox capacity is more closely related to the cyclability of the materials. We apply these insights and generate a capacity map of the Li-Mn-O-F chemical space, LixMn2-xO2-yFy (1.167 ≤ x ≤ 1.333, 0 ≤ y ≤ 0.667), which predicts both accessible Li capacity and Mn-redox capacity. This map allows the design of compounds that balance high capacity with good cyclability.
| Original language | English |
|---|---|
| Pages (from-to) | 153-168 |
| Number of pages | 16 |
| Journal | Chem |
| Volume | 6 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 9 2020 |
Funding
This work was supported by the Umicore Specialty Oxides and Chemicals and the Assistant Secretary for Energy Efficiency and Renewable Energy of the US Department of Energy (DOE) Vehicle Technologies Office (contract DEAC02-05CH11231) under the Advanced Battery Materials Research Program. Work at the Molecular Foundry was supported by the US DOE Office of Science and Office of Basic Energy Sciences (contract DE-AC02-05CH11231). The NMR experimental work used the shared facilities of the UCSB MRSEC (National Science Foundation [NSF] DMR 1720256), a member of the Materials Research Facilities Network. This research used resources of the Advanced Photon Source, a US DOE Office of Science user facility operated by Argonne National Laboratory, and was supported by the US DOE under contract DE-AC02-06CH11357. This research used resources at the Spallation Neutron Source, a DOE Office of Science user facility operated by the Oak Ridge National Laboratory. The computational analysis was performed using computational resources sponsored by the DOE Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. Computational resources were provided by Extreme Science and Engineering Discovery Environment, which was supported by NSF grant ACI1053575 and the National Energy Research Scientific Computing Center, a user facility supported by the DOE Office of Science (contract DE-AC02-05CH11231). J.K.P. gratefully acknowledges support from the NSF Graduate Research Fellowship (contract DGE-1106400). The authors thank Dr. Hyunchul Kim and Dr. Nongnuch Artrith for helpful discussion, Mr. Jingyang Wang for help with XAS measurement, and Dr. Jue Liu for help with neutron diffraction measurement. Z.L. planned the project with G.C.; Z.L. designed, synthesized, characterized (XRD), and electrochemically tested the proposed compounds with help from Z.C. H.J. and H.K.; B.O. performed Monte Carlo and DFT calculations and analyzed the data with help from D.A.K.; R.J.C. acquired and analyzed the NMR data; Z.L. acquired and analyzed the XAS data with the help of M.B. and J. H.; D.-H.K. acquired and analyzed TEM data; J.K.P. acquired and analyzed DEMS data with input from B.D.M.; Y.T. performed SEM. The manuscript was written by Z.L. and was revised by R.J.C. D.A.K. H.J. and G.C. with the help of the other authors. All authors contributed to discussions. The authors declare no competing interests. This work was supported by the Umicore Specialty Oxides and Chemicals and the Assistant Secretary for Energy Efficiency and Renewable Energy of the US Department of Energy (DOE) Vehicle Technologies Office (contract DEAC02-05CH11231 ) under the Advanced Battery Materials Research Program. Work at the Molecular Foundry was supported by the US DOE Office of Science and Office of Basic Energy Sciences (contract DE-AC02-05CH11231 ). The NMR experimental work used the shared facilities of the UCSB MRSEC ( National Science Foundation [NSF] DMR 1720256 ), a member of the Materials Research Facilities Network. This research used resources of the Advanced Photon Source, a US DOE Office of Science user facility operated by Argonne National Laboratory, and was supported by the US DOE under contract DE-AC02-06CH11357 . This research used resources at the Spallation Neutron Source, a DOE Office of Science user facility operated by the Oak Ridge National Laboratory. The computational analysis was performed using computational resources sponsored by the DOE Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. Computational resources were provided by Extreme Science and Engineering Discovery Environment, which was supported by NSF grant ACI1053575 and the National Energy Research Scientific Computing Center , a user facility supported by the DOE Office of Science (contract DE-AC02-05CH11231 ). J.K.P. gratefully acknowledges support from the NSF Graduate Research Fellowship (contract DGE-1106400 ). The authors thank Dr. Hyunchul Kim and Dr. Nongnuch Artrith for helpful discussion, Mr. Jingyang Wang for help with XAS measurement, and Dr. Jue Liu for help with neutron diffraction measurement.
Keywords
- cation-disordered rocksalt cathodes
- density functional theory
- fluorination
- Li percolation
- Li-excess Mn-based oxyfluorides
- Monte Carlo simulation
- SDG7: Affordable and clean energy
- short-range order