Biomass-Derived Ion-Selective Binder Modulates Zn²⁺ Solvation Enabling High-Capacity Cathodes in Aqueous Zinc...

Area of Science:

• Materials Science
• Electrochemistry
• Biomaterials

Background:

• Aqueous zinc batteries (AZBs) require advanced binders for optimal electrochemical performance.
• Hydrophobic binders like polyvinylidene fluoride (PVDF) hinder Zn²⁺ solvation and redox kinetics.

Purpose of the Study:

• To develop a bioinspired binder that regulates Zn²⁺ solvation and accelerates interfacial kinetics in AZBs.
• To mimic biological ion channels for selective ion coordination and hydration control.

Main Methods:

• Derived a sulfate-rich polysaccharide binder from marine ι-carrageenan (CAG).
• Investigated dual ion-selective coordination sites (─OSO₃^- and ─OH) for Zn²⁺ and H₂O interactions.
• Fabricated and tested Zn||CAG@Mn_0.15V₂O₅·nH₂O batteries.

Main Results:

• CAG binder disrupted the primary Zn²⁺-H₂O solvation shell, enhancing Zn²⁺ desolvation kinetics.
• Zn||CAG@Mn_0.15V₂O₅·nH₂O batteries achieved an ultrahigh capacity of 421 mAh g^-1, 76% higher than PVDF-based ones.
• Demonstrated universal applicability of CAG with various cathode materials (MnO₂, V₂O₅, organics).

Conclusions:

• CAG offers a green, scalable, water-processable binder for high-performance AZBs.
• The study presents a biomimetic binder design paradigm using dual sulfate-hydroxyl coordination.
• This approach enables precise regulation of Zn²⁺ solvation and interfacial chemistry in AZBs.