Engineering Anionic Aggregation in Dilute Electrolyte for High Performance Layered Oxide Cathodes for Sodium-Ion...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) offer advantages but face challenges in cycle stability and energy density.
• Layered oxide cathodes suffer irreversible structural changes, limiting SIB performance.

Purpose of the Study:

• To develop a novel electrolyte for improving the cycle stability and energy density of SIBs.
• To investigate the mechanism of a high-entropy electrolyte in stabilizing layered oxide cathodes.

Main Methods:

• Development of a dilute 0.5 M high-entropy electrolyte.
• Electrochemical characterization of the NaNi1/3Mn1/3Fe1/3O2 (NaNMF) cathode with the new electrolyte.
• Analysis of the cathode electrolyte interphase (CEI) formation.

Main Results:

• The dilute high-entropy electrolyte formed an inorganic-rich, dense CEI layer.
• The CEI layer effectively passivated the electrode and prevented solvent co-intercalation.
• The NaNMF cathode achieved 90% capacity retention after 250 cycles with excellent high/low temperature performance.

Conclusions:

• The innovative anionic aggregate structure in dilute high-entropy electrolytes is key to enhancing SIB performance.
• This approach offers a promising pathway for developing cost-effective, high-energy-density SIBs.
• The developed electrolyte significantly improves the stability of layered oxide cathodes in SIBs.