Concurrently Suppressing Side Reaction and Freezing in Flexible Zinc–Air Batteries with a Robust Eutectogel Electrolyte

Why It Matters

The breakthrough enables high‑performance, flexible zinc‑air power sources that function in extreme cold and heat, expanding their applicability in wearables, aerospace, and remote‑site electronics.

Key Takeaways

• Formamide eutectogel yields 184 mS cm⁻¹ conductivity
• Bound water suppresses hydrogen evolution and zinc corrosion
• Flexible Zn‑air cells operate from –115 °C to 70 °C
• CoFe@CNT catalyst delivers 121 mW cm⁻² peak power
• Gel retains 90 % liquid after 96 h exposure

Pulse Analysis

Flexible zinc‑air batteries have long been hampered by hydrogel electrolytes that lose water, suffer low ionic conductivity, and fail at sub‑zero temperatures. By leveraging deep eutectic solvents (DES) combined with polyvinyl alcohol, researchers created a eutectogel matrix that overcomes these limitations. The DES formulation, particularly the ethylene‑glycol‑formamide blend, forms a dense hydrogen‑bond network that retains moisture and delivers an ionic conductivity of 184 mS cm⁻¹, far surpassing traditional gels. This structural robustness also grants the electrolyte mechanical flexibility essential for wearable and conformable devices.

The chemistry of formamide is central to the performance gains. Its carbonyl (‑C=O) and amide (‑NH₂) groups convert free water into bound water, curbing the diffusion of Zn(OH)₄²⁻ species that typically trigger hydrogen evolution, corrosion, and dendrite formation on the zinc anode. The resulting suppression of side reactions yields a stable electrode interface and enables uniform zinc deposition. Additionally, the eutectogel exhibits a liquid retention of 90 % after 96 hours in ambient air, ensuring long‑term operation without electrolyte drying.

When paired with a CoFe alloy encapsulated in carbon nanotubes (CoFe‑CNT) as an efficient oxygen‑reduction catalyst, the eutectogel‑based FZAB achieves a peak power density of 121.1 mW cm⁻² and a specific capacity of 800 mAh gZn⁻¹. Most striking is its ultra‑wide operating temperature window, from –115 °C to 70 °C, a range unmatched by existing gel electrolytes. This capability opens doors for energy storage in extreme environments—such as high‑altitude drones, polar research stations, and next‑generation smart textiles—while maintaining safety and flexibility. The study signals a pivotal step toward commercializing robust, temperature‑resilient zinc‑air systems.