posted on 20.06.2018, 00:00by Tanghong Yi, Wei Chen, Lei Cheng, Ryan D. Bayliss, Feng Lin, Michael R. Plews, Dennis Nordlund, Marca M. Doeff, Kristin A. Persson, Jordi Cabana
Reversible intercalation reactions provide the basis for modern battery electrodes. Despite decades of exploration of electrode materials, the potential for materials in the non-oxide chemical space with regards to intercalation chemistry is vast and rather untested. Transition metal fluorides stand out as an obvious target. To this end, we report herein a new family of iron fluoride-based perovskite cathode materials AxK1-xFeF3 (A = Li, Na). Starting with KFeF3, approximately 75% of K+ ions were subsequently replaced by Li+ and Na+ through electrochemical means. X-ray diffraction and Fe X-ray absorption spectroscopy confirmed the existence of intercalation of alkali metal ions in the perovskite structure, which is associated with the Fe2+/3+ redox couple. A computational study by density functional theory (DFT) showed agreement with the structural and electrochemical data obtained experimentally, suggesting the possibility of fluoride-based materials as potential intercalation electrodes. This study increases our understanding of the intercalation chemistry of ternary fluorides, which could inform efforts toward the exploration of new electrode materials.
Work at Lawrence Berkeley National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05CH11231, as part of the Battery Materials Research (BMR) Program. MRP and JC acknowledge research start-up funding by the Department of Chemistry and the College of Liberal Arts and Sciences at the University of Illinois at Chicago. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Stanford University. Beamline 20-BM at the Advanced Photon Source (APS) is part of the Pacific Northwest Consortium-X-ray Science Division (PNC/XSD) facilities, supported by the U.S. DOE Office of Science, the Canadian Light Source (CLS) and its funding partners, the University of Washington, and the APS. Use of the APS, an Office of Science User Facility operated for the DOE by Argonne National Laboratory, was supported by Contract No. DE-AC02-06CH11357.
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Yi, T. H., Chen, W., Cheng, L., Bayliss, R. D., Lin, F., Plews, M. R., Nordlund, D., Doeff, M. M., Persson, K. A. and Cabana, J. Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites. Chemistry of Materials. 2017. 29(4): 1561-1568. 10.1021/acs.chemmater.6b04181.