Zincophile channel adjustment realizes dendrite-free zinc anode for low-temperature zinc-ion capacitors

The aqueous zinc-ion hybrid capacitors (ZIHCs) have promising applications for large-scale energy storage due to high safety and low cost. However, the ZIHCs suffer from the poor cycling performance and the inability of the device to operate at freezing point. Herein, we designed an integrated device architecture consisting of a copper-tin nanowires (Cu-Sn NWs) array loaded zinc substrate with 3D pro-zinc channels assembled in-situ with a freeze-resistant electrolyte to realize flexible ZIHCs based on a dendrite free zinc anode. The Cu-Sn NWs with extremely low zinc nucleation overpotential induce uniform zinc deposition by homogenizing the electric field, while the resulting 3D nanowire array scaffold with ample internal space buffers the volume changes during the stripping/plating process. As-fabricated Zn-loaded substrate shows an extremely low voltage polarization of 23 mV and the outstanding ability to stably stripping/plating for 1200 h at 5 mA cm−1. Furthermore, the as-assembled flexible ZIHC is outstanding cycling performance (nearly 85.5% capacitance retention after 10,000 cycles at –20 °C) by in-situ polymerization of anti-freeze acrylamide-based composite hydrogel electrolyte on the zinc-loaded substrate. The strategy helps to stimulate the application of high-performance dendrite-free flexible energy-storage devices in cold environment.