Slurry Additive Approach Enables a Mechanically Robust Binder for Silicon-Carbon Anodes in Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon-carbon (Si/C) composites are promising for high-specific-energy lithium-ion batteries (LIBs).
• Silicon's large volume expansion during cycling causes electrode degradation, limiting its application.
• Conventional poly(acrylic acid) (PAA) binders lack the mechanical integrity to withstand silicon's volume changes.

Purpose of the Study:

• To develop a novel binder system that accommodates silicon's volume expansion and enhances electrode stability.
• To improve the cycling performance and longevity of Si/C anodes in LIBs.

Main Methods:

• Utilized polyether modified polyurethane acrylic (PUMA) as a physicochemical co-crosslinking polymer.
• Incorporated PUMA as a slurry additive with PAA to create a composite binder.
• Investigated the binder's effect on electrode integrity, SEI film formation, and electrochemical performance in Si/C450 half-cells and Si/C450||NCM811 full cells.

Main Results:

• The PUMA-PAA composite binder demonstrated superior mechanical properties, elasticity, and interfacial stability.
• Electrodes with the enhanced binder exhibited excellent cycling stability, retaining 97.26% capacity after 200 cycles (0.5 C) in half-cells.
• Full cells achieved 82.10% capacity retention after 100 cycles (0.2 C) when paired with NCM811 cathodes.

Conclusions:

• The PUMA-based composite binder effectively mitigates silicon volume expansion and prevents electrode fracture.
• This binder design promotes the formation of a stable solid electrolyte interphase (SEI) film.
• The developed binder shows significant potential for advancing silicon-based anodes in high-energy LIB applications.