Carbon nanotube-based ternary-additive restructured hydrogel electrolyte for high-performance flexible Zn-air batteries

The growing demand for flexible electronics and wearable devices has positioned flexible zinc-air batteries as a promising research focus, owing to their inherent safety, low cost, and high theoretical capacity. However, a key challenge remains in developing hydrogel electrolytes that simultaneously offer high ionic conductivity and effective water retention. Herein, we address this by structurally reforming a poly (acrylic acid)-AMPS hydrogel using a synergistic ternary additive system of hydroxylated carbon nanotubes, tannic acid, and potassium formate. Cryo-SEM analysis reveals that the modified hydrogel transforms from a dense-walled architecture into a rich, interpenetrating polymer-CNT network, reducing internal resistance and achieving a high ionic conductivity of 513.48 mS·cm⁻¹ . The restructured network exposes more oxygen-containing functional groups, significantly enhancing both water retention and electrolyte uptake. Molecular dynamics simulations confirm that the formate additive further disrupts the solvation structure of Zn²⁺, suppressing detrimental side reactions. Consequently, the assembled flexible Zn-air battery, delivers a peak power density of 124.61 mW·cm⁻² and a specific capacity of 756.12 mAh·g_Zn⁻¹ , with stable operation exceeding 90 h. This work provides a viable strategy for designing high-performance hydrogel electrolytes, demonstrating significant potential for advancing flexible aqueous metal-air batteries.