Solvating power regulation enabled low concentration electrolyte for lithium batteries

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Lithium-ion solvation structures critically impact electrode/electrolyte interfaces and battery performance.
• Low concentration electrolytes (LCEs) are challenging due to unstable solid electrolyte interfaces (SEIs) formed with high organic content.
• Solvents with low solvating power offer a promising strategy for developing stable LCEs by weakening salt-solvent interactions.

Purpose of the Study:

• To investigate the potential of low solvating power solvents in enabling stable LCEs.
• To explore the formation of the solid electrolyte interface (SEI) in LCEs with specific solvent mixtures.
• To evaluate the electrochemical performance of batteries utilizing these novel LCEs.

Main Methods:

• Preparation of a low concentration electrolyte (0.25 mol L⁻¹) using fluoroethylene carbonate (FEC) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether (D₂).
• Utilized molecular dynamics simulations to understand Li⁺ solvation and interfacial behavior.
• Conducted electrochemical experiments using Li||Cu and LiNi₀.₆Co₀.₂Mn₀.₂O₂||Li cells to assess battery performance.

Main Results:

• The low solvating power solvent (FEC) reduced Li⁺ desolvation energy, enhancing battery kinetics.
• Promoted the formation of a LiF-rich SEI, effectively suppressing electrolyte consumption.
• Achieved high coulombic efficiency (99.20% in Li||Cu cells) and good capacity retention (89.93% over 200 cycles in LiNi₀.₆Co₀.₂Mn₀.₂O₂||Li cells).

Conclusions:

• Solvating power regulation is a viable strategy for developing high-performance LCEs.
• The developed LCE demonstrates excellent electrochemical stability and efficiency.
• This approach holds significant potential for advancing next-generation battery technologies.