Dip-coating processed sponge-based electrodes for stretchable Zn-MnO₂ batteries

Stretchable electronics are in high demand for next-generation wearable devices, but their fabrication is still challenging. Stretchable conductors, flexible pressure sensors, and foldable light-emitting diodes (LEDs) have been reported; however, the fabrication of stable stretchable batteries, as power suppliers for wearable devices, is significantly behind the development of other stretchable electronics. Several stretchable lithium-ion batteries and primary batteries have been fabricated, but their low capacities and complicated manufacturing processes are obstacles for practical applications. Herein, we report a stretchable zinc/manganese-oxide (Zn-MnO₂) full battery based on a silver-nanowire-coated sponge prepared via a facile dip-coating process. The spongy electrode, with a three-dimensional (3D) binary network structure, provided not only high conductivity and stretchability, but also enabled a high mass loading of electrochemically active materials (Zn and MnO₂ particles). The fabricated Zn-MnO₂ battery exhibited an areal capacity as high as 3.6 mAh·cm^-2 and could accommodate tensile strains of up to 100% while retaining 89% of its original capacity. The facile solution-based strategy of dip-coating active materials onto a cheap sponge-based stretchable current collector opens up a new avenue for fabricating stretchable batteries.