Tuning Interphase Composition in Sodium-Ion Batteries via Co-Solvent Selection and Anion-Driven Solvation Shell...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Unstable interphases on anodes and cathodes limit sodium-ion full cell cycling performance.
• Developing stable and efficient sodium-ion batteries is crucial for next-generation energy storage.

Purpose of the Study:

• To investigate the effect of low-viscosity, weakly solvating linear carbonates (dimethyl carbonate and diethyl carbonate) on sodium-ion full cell interphase formation.
• To enhance the cycling stability and rate performance of sodium-ion full cells.

Main Methods:

• Utilizing dimethyl carbonate (DMC) and diethyl carbonate (DEC) as electrolyte components.
• Analyzing interphase formation on hard carbon (HC) anodes and NMTNO cathodes.
• Evaluating full-cell performance through cycling stability and rate capability tests.

Main Results:

• The electrolyte promoted anion involvement in the solvation shell, forming an anion-rich, ion-conducting interphase on the HC anode.
• An inorganic-rich cathode electrolyte interphase (CEI) formed on the NMTNO cathode.
• The full-cell achieved a stable areal capacity of 1.25 mAh cm⁻² at 0.25 mA cm⁻² after 200 cycles.
• Impressive high-rate performance was observed, maintaining 0.75 mAh cm⁻² at 1.5 mA cm⁻² with >90% capacity retention after 300 cycles.

Conclusions:

• Low-viscosity linear carbonates effectively stabilize anode and cathode interphases in sodium-ion full cells.
• The modified electrolyte significantly improves initial coulombic efficiency, rate performance, and long-term cycling stability.
• This electrolyte strategy offers a promising pathway for developing high-performance sodium-ion batteries.