CNTs-reinforced interpenetrating network within hydrogel electrolytes for enhanced Zn anode stability

Aqueous zinc-ion batteries (AZIBs) are highly promising for large-scale energy storage due to their intrinsic safety and low cost. However, their practical deployment is hindered by several challenges in liquid electrolytes, including zinc dendrite growth, undesirable side reactions, and interfacial instability. Hydrogel electrolytes, with their three-dimensional polymer networks, offer a compelling alternative by physically suppressing dendrite formation and enhancing device safety. Yet, conventional hydrogels often suffer from non-uniform salt distribution, insufficient mechanical strength, and poor interfacial regulation, issues that are especially pronounced when prepared via post-gelation salt immersion, ultimately compromising ion transport and causing inconsistent electrochemical performance. To overcome these limitations, this work designs an advanced in situ interpenetrating network composite strategy that synergistically integrates functional polymers and conductive nanofillers. Specifically, a carbon nanotubes (CNTs)-reinforced polyacrylamide (PAM)-xanthan gum (XG) hydrogel electrolyte, denoted as CNTs-PAM-XG, was fabricated through in situ polymerization in the presence of dissolved zinc sulfate, thereby ensuring homogeneous salt distribution and robust structural integrity. The resulting electrolyte exhibits excellent mechanical properties, with a fracture strength of 130 kPa and a tensile strain exceeding 320%, while maintaining stable ion conduction pathways, as confirmed by the simultaneous increase in both total ionic conductivity and Zn²⁺ transference number. In Zn//Zn symmetric cells, the electrolyte enables stable cycling for over 2100 h at a current density of 1 mA cm⁻². Moreover, Zn//MnO₂ full cells achieve 72.2% capacity retention after 1500 cycles at 1 A g⁻¹ , representing a significant improvement over traditional single-network hydrogel. Microstructural analyses reveal that the CNTs network facilitates a homogenized ion flux, while the functional groups in XG effectively modulate the Zn²⁺ solvation environment. These synergistic effects collectively inhibit dendritic growth and mitigate detrimental side reactions. Overall, this work provides a viable design strategy for developing high-performance and durable electrolyte systems suitable for AZIBs.