Green Electrode Processing Enabled by Fluoro-Free Multifunctional Binders for Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Eco-friendly processing of conjugated polymer binders for lithium-ion batteries requires improved solubility, often at the cost of conductivity.
• Polyfluorene-based polymers offer potential but face challenges in balancing solubility and conductivity.

Purpose of the Study:

• To develop a novel approach for aqueous solution processing of conjugated polymer binders that overcomes the trade-off between solubility and conductivity.
• To create hierarchically ordered structures (HOS) from a polyfluorene-based binder (PFO) for enhanced electrochemical performance.

Main Methods:

• Utilized poly(2,7-9,9 (di(oxy-2,5,8-trioxadecane))fluorene) (PFO), soluble in water-ethanol mixtures.
• Integrated aqueous solution processing with controlled thermal-induced cleavage of solubilizing side chains to form HOS-PFO.
• Fabricated SiOx anodes using HOS-PFO as a binder, demonstrating in situ side chain decomposition.

Main Results:

• Achieved a 6-7 orders of magnitude enhancement in electronic conductivity of the polyfluorene binder through HOS formation.
• Demonstrated stable cycling and high-capacity retention (3.0 mAh cm⁻²) for SiOx anodes without conducting carbon or fluorinated electrolyte additives.
• HOS-PFO facilitated improved intermolecular π-π stacking, enhancing electrochemical performance.

Conclusions:

• The developed technique offers a universal approach for fabricating electrodes with conjugated polymer binders from aqueous solutions without compromising conductivity.
• Hierarchically ordered structures (HOS) from PFO binders significantly improve electronic conductivity and electrochemical performance in lithium-ion batteries.
• This method enables the use of advanced materials like SiOx anodes with high stability and capacity.