Highly Stable Silicon Anode Enabled by a Water-Soluble Tannic Acid Functionalized Dual-Network Binder

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Silicon (Si) offers high capacity for lithium-ion batteries but suffers from poor cycling stability due to large volume changes.
• Developing robust binders is critical for stabilizing Si anodes and realizing high-energy-density batteries.

Purpose of the Study:

• To synthesize and evaluate a novel tannic acid functionalized aqueous dual-network binder (Alg(Ni)-PAM-TA) for stabilizing silicon anodes.
• To investigate the binder's structure-property relationships and its impact on electrode integrity and electrochemical performance.

Main Methods:

• Synthesis of an aqueous dual-network binder composed of alginate and polyamide functionalized with tannic acid.
• Characterization of binder properties, including adhesion and network resilience.
• Electrochemical testing of Si anodes using the developed binder.
• Molecular dynamics (MD) simulations to understand binder network behavior.

Main Results:

• The Alg(Ni)-PAM-TA binder exhibits strong interactions with Si nanoparticles and Cu foil, forming a resilient network with exceptional adhesion.
• MD simulations reveal increased intramolecular hydrogen bonding and aggregation of tannic acid, contributing to binder stability.
• Si anodes with the Alg(Ni)-PAM-TA binder demonstrated significantly enhanced cycling stability.
• A capacity retention of 1863.4 mAh g^-1 after 200 cycles at 0.84 A g^-1 was achieved.

Conclusions:

• The tannic acid functionalized aqueous dual-network binder effectively stabilizes Si anodes, overcoming volume expansion issues.
• This binder design offers a promising strategy for developing high-energy-density lithium-ion batteries.
• The intramolecular network formation via tannic acid incorporation is key to enhanced binder performance.