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Stabilisation of Li-rich disordered rocksalt oxyfluoride cathodes by particle surface modification

DOI: 10.1021/acsaem.0c00839 DOI Help

Authors: Andrew J. Naylor (Uppsala University) , Ida Kallquist (Uppsala University) , David Peralta (Université Grenoble-Alpes, CEA-LITEN) , Jean-frederic Martin (Université Grenoble-Alpes, CEA-LITEN) , Adrien Boulineau (Université Grenoble-Alpes, CEA-LITEN) , Jean-francois Colin (Université Grenoble-Alpes, CEA-LITEN) , Christian Baur (Helmholtz Institute Ulm) , Johann Chable (Université Grenoble-Alpes, CEA-LITEN) , Maximilian Fichtner (Helmholtz Institute Ulm; Karlsruhe Institute of Technology) , Kristina Edstrom (Uppsala University) , Maria Hahlin (Uppsala University) , Daniel Brandell (Uppsala University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Applied Energy Materials

State: Published (Approved)
Published: May 2020
Diamond Proposal Number(s): 20870

Abstract: Promising theoretical capacities and high voltages are offered by Li-rich disordered rocksalt oxyfluoride materials as cathodes in lithium ion batteries. However, as has been discovered for many other Li-rich materials, the oxyfluorides suffer from extensive surface degradation, leading to severe capacity fading. In the case of Li2VO2F, we have previously determined this to be a result of detrimental reactions between an unstable surface layer and the organic electrolyte. Herein, we present the protection of Li2VO2F particles with AlF3 surface modification, resulting in a much enhanced capacity retention over 50 cycles. While the specific capacity for the untreated material drops below 100 mA h g-1 after only 50 cycles, the treated materials retain almost 200 mA h g-1. Photoelectron spectroscopy depth profiling confirms the stabilisation of the active material surface by the surface modification and reveals its suppression of electrolyte decomposition.

Journal Keywords: Lithium-ion batteries; Li-rich cathodes; disordered rocksalt; particle coatings; surface modifications; surface passivation; photoelectron spectroscopy

Subject Areas: Materials, Chemistry, Energy

Instruments: I09-Surface and Interface Structural Analysis