Fluorinated ether electrolyte with controlled solvation structure for high voltage lithium metal batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Conventional electrolytes for lithium metal batteries face limitations like narrow electrochemical windows and poor stability.
• Fluorinated ethers offer high voltage stability but struggle with lithium-ion solvation, creating a critical challenge in electrolyte design.

Purpose of the Study:

• To design and synthesize a novel solvent that combines the high voltage stability of fluorinated ethers with the strong lithium-ion solvation of traditional ethers.
• To evaluate the performance of this new solvent in high-voltage lithium metal battery applications.

Main Methods:

• Synthesis of 2,2-dimethoxy-4-(trifluoromethyl)-1,3-dioxolane (DTDL), a novel solvent molecule.
• Electrochemical stability testing of DTDL-based electrolytes.
• Evaluation of lithium-ion transport properties, including transference number.
• Long-term cycling performance assessment in lithium metal battery full cells.

Main Results:

• DTDL exhibits high oxidation stability up to 5.5 V.
• A high lithium-ion transference number of 0.75 was achieved.
• Stable Coulombic efficiency of 99.2% over 500 cycles was demonstrated.
• A LiNi_0.8Co_0.1Mn_0.1O₂ full cell with DTDL electrolyte retained 84% capacity after 200 cycles.

Conclusions:

• DTDL effectively combines high voltage stability and good lithium-ion solvation in a single molecule.
• The novel solvent shows significant potential for advancing high-voltage lithium metal battery technology.
• DTDL-based electrolytes offer a promising pathway for next-generation energy storage solutions.