Sericin-Regulated Aqueous Network Binder for High-Performance Si─C Anodes and NCM811/Si─C Pouch Cells

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Silicon-carbon (Si─C) anodes offer high capacity but face challenges with silicon volume expansion and poor interfacial adhesion.
• Conventional binders like polyacrylic acid (PAA) and carboxymethyl cellulose (CMC) exhibit high polarity, leading to weak interactions with nonpolar carbon materials.

Purpose of the Study:

• To develop a novel ternary binder (PSC) using silk sericin (SS) to improve the interfacial properties of Si─C anodes.
• To enhance the electrochemical performance and cycling stability of Si─C anodes by addressing volume expansion and interfacial issues.

Main Methods:

• Formulation of a ternary binder (PSC) by incorporating silk sericin (SS) with polyacrylic acid (PAA) and carboxymethyl cellulose (CMC).
• Investigation of the in-situ cross-linked network formation within the PSC binder during electrode drying, involving ester and hydrogen bonds.
• Evaluation of the binder's dual-interfacial binding capability through hydrogen bonds with silicon and π-π interactions with carbon.

Main Results:

• The PSC binder facilitates dual-interfacial binding, anchoring silicon via hydrogen bonds and carbon via π-π interactions, leading to improved adhesion and component dispersion.
• A full pouch cell utilizing a Si─C anode with the LPSC binder (CMC, SS, and neutralized PAA) and an NCM811 cathode demonstrated excellent stability.
• The cell retained over 74% of its initial capacity after 300 cycles at a 1 C rate, showcasing the binder's effectiveness.

Conclusions:

• The developed silk sericin-based ternary binder (PSC) effectively addresses the interfacial challenges in Si─C anodes.
• This binder strategy offers a practical approach to enhance the commercial viability of high-performance silicon-based anodes for advanced battery applications.