Flexible energy storage devices are an indispensable part of rapidly advancing wearable technologies. An optimal energy storage device for wearable applications would need to have high energy density and long cycle life, remain stable under deformation and allow simple integration into existing and future wearables.
Here we expand on utilizing silver-zinc battery chemistry and low cost fabrication processes to construct flexible wire-shaped battery with improved electrochemical stability and high linear capacity. Wire-shaped architecture is mechanically robust and offers versatile integration options. The silver-zinc battery chemistry is energy dense and is based on an aqueous electrolyte, which makes it inherently safe. In order to achieve long cycle life of these batteries, we hinder silver migration both by optimizing the concentration of potassium hydroxide in the electrolyte to prevent silver dissociation and by implementing a cellophane layer to impede the ion migration.
The resulting wire battery demonstrated stable performance for up to 170 cycles and specific capacity as high as 1.41 mAh/cm. Mechanically, the battery is shown to withstand repeated flexing to a bending radius of 1 cm.