Prelithiated rigid polymer with high ionic conductivity as silicon-based anode binder for lithium-ion battery

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Silicon anodes in lithium-ion batteries degrade due to significant volume expansion during cycling.
• Developing effective polymer binders is crucial for stabilizing silicon electrodes and improving battery longevity.

Purpose of the Study:

• To introduce and evaluate a novel water-soluble rigid-rod polymer, poly(2,2 -disulfonyl-4,4 -benzidine terephthalamide) (PBDT), as a binder for silicon-based electrodes.
• To investigate the role of PBDT's molecular structure and prelithiation strategy in enhancing electrode performance.

Main Methods:

• Synthesis and characterization of the PBDT polymer.
• Fabrication of silicon-based electrodes using PBDT as a binder.
• Electrochemical testing, including cycling stability and initial coulombic efficiency measurements.
• Analysis of solid electrolyte interface (SEI) formation and ion transport properties.

Main Results:

• PBDT effectively inhibits silicon volume expansion through hydrogen bonding interactions.
• The PBDT binder promotes the formation of stable solid electrolyte interfaces (SEI).
• Prelithiated PBDT exhibits high ionic conductivity (3.2 × 10^-4 S cm^-1), enhancing Li-ion transport and compensating for irreversible capacity loss.

Conclusions:

• The PBDT binder significantly improves the cycling stability and initial coulombic efficiency of silicon-based electrodes compared to traditional PVDF binders.
• The study highlights the critical role of polymer binder molecular design and prelithiation in overcoming performance limitations of high-volume expansion silicon anodes.