Microphase-Separated Hydrogel Electrolytes with Selective Ion Transportation Pathways for Flexible Zinc-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Flexible aqueous zinc-ion batteries (ZIBs) are crucial for wearable electronics but face challenges from conventional hydrogel electrolytes.
• Non-selective ion transport in hydrogels leads to dendrite formation and battery failure.

Purpose of the Study:

• To engineer a microphase-separated single-zinc-ion conducting hydrogel electrolyte (SIHE) for improved ZIB performance.
• To overcome the trade-off between ion selectivity and transport kinetics in ZIB electrolytes.

Main Methods:

• Constructed a zinc-alginate (ZA) matrix and incorporated Nafion to induce microphase separation.
• Utilized polymer chain disentanglement and domain engineering to create continuous Zn²⁺ pathways.
• Characterized the electrolyte's ion transport properties, including transference number and ionic conductivity.

Main Results:

• Achieved a high Zn²⁺ transference number of 0.967 and ionic conductivity of 25.5 mS cm^-1.
• Demonstrated dendrite-free cycling for over 4600 hours with the zinc-alginate/Nafion (ZA/N) electrolyte.
• The ZA/N-based flexible ZIB retained 90% capacity after 5000 cycles at 10 A g^-1.

Conclusions:

• The microphase-separated SIHE strategy effectively enhances ion selectivity and transport kinetics.
• This approach offers a general method for developing high-performance, safe, and durable flexible ZIBs.
• The developed electrolyte is promising for next-generation wearable electronics and soft robotics.