Mechanically Robust Polyimide Binder Realizes Stable and High Electrochemical Performance for Micro-Silicon Anodes in...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon anodes offer high theoretical capacity for lithium-ion batteries but suffer from significant volumetric expansion and side reactions during cycling.
• Effective binders are crucial for mitigating stress and maintaining electrode integrity in silicon-based anodes.

Purpose of the Study:

• To develop a mechanically robust polyimide binder (PI-CF3) with trifluoromethyl and hydroxyl groups for microparticle silicon anodes.
• To investigate the binder's ability to enhance the electrochemical performance and cycling stability of silicon anodes.

Main Methods:

• Synthesis of a novel polyimide binder (PI-CF3) incorporating -CF3 and -OH functional groups.
• Characterization of the binder's mechanical properties (Young's modulus) and electrode morphology.
• Electrochemical testing of micro-Si anodes using the PI-CF3 binder, including capacity retention and cycling stability analysis.

Main Results:

• The PI-CF3 binder exhibited a high Young's modulus (~921.1 MPa), providing excellent mechanical resilience to the silicon anode.
• The -OH and -CF3 groups facilitated interactions with the silicon surface, forming a stable cross-linked network and improving interface stability.
• The micro-Si anode with PI-CF3 binder achieved an initial specific capacity of 1838 mAh g⁻¹ and retained 1219 mAh g⁻¹ after 330 cycles at high mass loading (0.78 mg cm⁻²), with a low capacity decay rate of 0.061% per cycle.

Conclusions:

• The developed PI-CF3 binder effectively stabilizes the silicon anode structure and facilitates Li+ transportation, overcoming key limitations of silicon anodes.
• This binder shows significant promise for advancing the performance and durability of next-generation lithium-ion batteries.