Flexible Zn-ion Electrochromic Batteries with Multiple-color Variations

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Electrochromic batteries offer visual energy monitoring but face limitations in capacity, stability, and color range.
• Flexible smart energy devices are crucial for wearable electronics.

Purpose of the Study:

• To develop a high-performance, flexible zinc-ion electrochromic battery (ZIEB) overcoming current limitations.
• To enable real-time visual energy status indication and stable power output in flexible devices.

Main Methods:

• Assembled a ZIEB using a sodium vanadate cathode, an ion-redistributing hydrogel electrolyte, and a zinc anode.
• The hydrogel electrolyte featured anchored -SO3- and -NH3+ groups to improve ionic transport and zinc deposition.
• Tested the ZIEB's electrochemical performance, cycling stability, color transitions, and mechanical flexibility.

Main Results:

• Achieved a high specific capacity of 302.4 mAh·g⁻¹ at 0.05 A·g⁻¹.
• Demonstrated excellent cycling stability with 96.3% capacity retention after 500 cycles at 3 A·g⁻¹.
• Exhibited continuous reversible color transitions (orange to brown to green) and stable energy output under mechanical stress (bending, rolling, knotting, twisting).

Conclusions:

• The developed ZIEB addresses key challenges in electrochromic battery technology, offering improved performance and flexibility.
• This work presents a viable strategy for designing advanced smart energy devices for wearable applications.