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Stabilization of Li-Rich Disordered Rocksalt Oxyfluoride Cathodes by Particle Surface Modification
Andrew J Naylor1, Ida Källquist2, David Peralta3
1Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden.
ACS Applied Energy Materials
|September 21, 2020
Summary
Protecting lithium-rich oxyfluoride cathodes with aluminum fluoride (AlF3) significantly improves lithium-ion battery performance. This surface modification enhances capacity retention and prevents electrolyte decomposition, crucial for next-generation energy storage.
Area of Science:
- Materials Science
- Electrochemistry
- Energy Storage
Background:
- Li-rich disordered rocksalt oxyfluorides offer high theoretical capacities and voltages for lithium-ion battery cathodes.
- These materials suffer from surface degradation and capacity fading due to reactions with organic electrolytes.
- Li2VO2F, a promising oxyfluoride, exhibits poor cycling stability linked to its unstable surface layer.
Purpose of the Study:
- To enhance the electrochemical performance and stability of Li2VO2F cathode material.
- To investigate the efficacy of aluminum fluoride (AlF3) surface modification for protecting Li2VO2F.
- To understand the mechanism of surface stabilization and its impact on electrolyte interactions.
Main Methods:
- Surface modification of Li2VO2F particles with AlF3.
- Electrochemical cycling tests to evaluate capacity retention over 50 cycles.
- Photoelectron spectroscopy depth profiling to analyze surface composition and stability.
Main Results:
- AlF3 surface modification significantly improved capacity retention of Li2VO2F.
- Treated materials retained nearly 200 mA h g-1 after 50 cycles, compared to <100 mA h g-1 for untreated material.
- Spectroscopic analysis confirmed surface stabilization and suppressed electrolyte decomposition.
Conclusions:
- AlF3 surface modification is an effective strategy to protect Li2VO2F from electrolyte degradation.
- This approach enhances the cycling stability and practical applicability of Li-rich oxyfluoride cathodes.
- The study provides insights into stabilizing advanced cathode materials for improved lithium-ion batteries.
