A Multifunctional Binder for Current-Collector-Free Zn Powder Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Zinc powder (ZP) anodes offer processing advantages over zinc foil but suffer from dendrite growth and side reactions in aqueous electrolytes.
• These issues limit the reversibility and performance of ZP anodes, particularly in high-loading mass cathodes.
• Developing stable ZP anodes is crucial for advancing high-energy-density battery technologies.

Purpose of the Study:

• To develop a novel binder for stabilizing zinc powder anodes in aqueous electrolytes.
• To investigate the binder's ability to regulate zinc ion flux and suppress side reactions.
• To evaluate the electrochemical performance of ZP anodes and their application in zinc-iodine full cells.

Main Methods:

• A diisocyanate-polytetrahydrofuran-dihydrazide polymer (DDP) binder was synthesized, inspired by protein structures.
• The DDP binder's Zn2+ adsorption and hydrogen-bonding capabilities were utilized to form free-standing ZP anodes.
• Mechanical properties of ZP electrodes were tested using tensile, nanoindentation, scratch, and bending tests.
• ZP symmetric cells and ZP/DDP||I2/DDP full cells were assembled and cycled to assess performance.

Main Results:

• The DDP binder demonstrated strong Zn2+ adsorption and facilitated the formation of stable, free-standing ZP anodes.
• ZP electrodes with DDP binder exhibited excellent mechanical robustness against various stresses.
• ZP symmetric cells achieved stable cycling at 2 and 5 mAh cm-2.
• The DDP binder also functioned effectively as an iodine cathode, suppressing the polyiodide shuttle.
• Fabricated ZP/DDP||I2/DDP full cells showed excellent rate capability and cycling stability, even under high-loading conditions.

Conclusions:

• The DDP binder provides a novel and effective strategy for preparing stable zinc powder anodes.
• The binder's dual functionality as an anode stabilizer and cathode component enables high-performance zinc-iodine batteries.
• This approach offers a promising pathway for the large-scale application of zinc-based energy storage systems.