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Improving capacity retention of Li2VO2F Li-rich cathodes with film-forming additives

DOI: 10.1021/acs.jpcc.0c02840 DOI Help

Authors: Ida Kallquist (Uppsala University) , Jean-frederic Martin (CEA-LITEN) , Andrew Naylor (Uppsala University) , Christian Baur (Helmholtz Institute Ulm) , Maximilian Fichtner (Helmholtz Institute Ulm; Karlsruhe Institute of Technology) , Jean-francois Colin (CEA-LITEN) , Daniel Brandell (Uppsala University) , Kristina Edstrom (Uppsala University) , Maria Hahlin (Uppsala University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C

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

Abstract: Li-rich disordered rock-salt structures have due to their high theoretical capacity gained large attention as a promising class of cathode materials for battery applications. However, the cycling stability of these materials have so far been less satisfactory. Here, we present three different film forming electrolyte additives; lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB), and glycolide, which all improve the cycling performance of the high capacity Li-rich disordered rock-salt material Li2VO2F. The best performing additive, LiODFB, show a 12.5% increase of capacity retention after 20 cycles. The improved cycling performance is explained by the formation of a more robust cathode interphase on the electrode surface. Photoelectron spectroscopy is used to show that the surface layer is created from oxidation of the electrolyte salt and additive co-salts. This passivating layer can mitigate oxidation and following degradation of the active material, and thus a higher degree of redox active vanadium can be maintained after 20 cycles.

Subject Areas: Chemistry, Materials, Energy

Instruments: I09-Surface and Interface Structural Analysis