Synthesis of Hollow Polyaniline Nanospheres via Surface Tension‐Guided Double Emulsion System for Zn Carriers in Aqueous Batteries

ABSTRACT Hollow mesoporous architectures present new opportunities for electrode design, yet conventional syntheses remain hampered by tedious hard‐template or unstable soft‐templates. Herein, a surface tension‐guided double‐emulsion template strategy is reported for the one‐step synthesis of uniform hollow polyaniline (PANI) nanospheres. Distinct from disordered emulsions, this double emulsion architecture features a central monomer droplet stabilized by a discrete intermediate micellar layer. By precisely modulating the solvent surface tension, the sizes of the hollow nanospheres are finely tuned, achieving diameters of 130–500 nm, cavities of 70–300 nm, and shell thicknesses of 30–80 nm. The resulting hollow PANI host creates a synergistic mechanism to regulate zinc deposition: chemically, the abundant nitrogen sites reduce the nucleation energy barrier; geometrically, the concave interior surface induces a negative curvature effect that enriches zinc ions, thereby guiding preferential deposition within the cavity. Capitalizing on these merits, the zinc‐preloaded hollow PANI anode exhibits exceptional stability and utilization. When assembled into full cells, this lightweight host enables a high specific capacity of 273 mAh g −1 while achieving a remarkably low negative‐to‐positive (N/P) ratio of 1.91. This work demonstrates that the double‐emulsion‐engineered hollow architecture is a promising route for developing high‐energy‐density, lightweight carriers for aqueous zinc batteries.