An innovative dehydrofluorinated composite gel electrolyte for enhanced solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Organic-inorganic composite electrolytes face challenges in enhancing ionic conductivity and Li-ion conduction sites.
• Improving Li-ion transport is crucial for developing high-performance solid-state batteries.

Purpose of the Study:

• To develop a single-ion conducting composite gel electrolyte (CGE-Li3OCl) using a dehydrofluorination reaction of PVDF.
• To investigate the effect of this reaction on organic-inorganic phase interactions and Li-ion conduction.
• To evaluate the electrochemical performance and stability of the developed electrolyte in solid-state batteries.

Main Methods:

• Preparation of PVDF-Li3OCl-FEC composite gel electrolyte (CGE-Li3OCl) via dehydrofluorination.
• Characterization of electrolyte properties including ionic conductivity, Li-ion transference number, and electrochemical window.
• Fabrication and testing of Li/Li symmetric cells and Li/NCA cells using the developed electrolyte.

Main Results:

• The optimal CGE40-Li3OCl exhibited an ionic conductivity of 2.73 × 10^-4 S cm^-1, a Li-ion transference number of 0.90, and an electrochemical window > 4.78 V.
• The electrolyte demonstrated stable operation for over 2500 h in Li/Li symmetric cells, suppressing lithium dendrite growth.
• Li/CGE40-Li3OCl/NCA cells showed 84.15% capacity retention after 350 cycles, outperforming Li/CGE40-LLZTO/NCA cells.

Conclusions:

• The dehydrofluorination reaction effectively enhances organic-inorganic phase interactions and facilitates fast ionic conductivity.
• The CGE-Li3OCl electrolyte exhibits excellent electrochemical stability and mechanical properties, making it suitable for high-performance solid-state batteries.
• This novel electrolyte represents a promising advancement for next-generation energy storage applications.