Silica-reinforced semi-solid hydroxypropyl cellulose hydrogel electrolytes for dendrite-free aqueous zinc-ion batteries

초록

Aqueous Zn-ion batteries (AZIBs) are promising energy storage systems because of their intrinsic safety, low cost, and high theoretical capacity of Zn metal. However, liquid aqueous electrolytes suffer from severe interfacial instability-including hydrogen evolution reactions, interfacial corrosion, by-product formation, and dendritic Zn growth-resulting from unregulated Zn2+ transport and nonuniform Zn deposition. Herein, we report a silicareinforced hydroxypropyl cellulose (HPC)-based semi-solid hydrogel electrolyte that forms ion transport pathways within polymer-rich regions and silica-rich exclusion zones to create a water-poor microenvironment for stable interfacial Zn redox reactions. Compared with poly(vinyl alcohol)-a representative linear polymer-HPC provides a more favorable molecular environment for Zn2+ transport, as evidenced by higher Zn2+ diffusivity and stronger Zn2+ - polymer coordination. Among the electrolytes with different silica contents, the optimized electrolyte (6 wt% silica, HS6) exhibits the highest ionic conductivity of 45.8 +/- 1.5 mS cm(-1) and a Zn2+ transference number of 0.88 +/- 0.02 while suppressing corrosion and water-driven parasitic reactions and promoting homogeneous Zn deposition. Zn & Vert;V2O5-C full and pouch cells employing HS6 further demonstrate improved electrochemical performance and practical battery operation. These findings present a microenvironment-engineered hydrogel electrolyte strategy for practical AZIB systems.

키워드