The need of power sources for rapidly advancing wearable technologies facilitated exciting research in the field of compliant energy storage. Although a variety of compliant battery systems has been demonstrated up to date, significant challenges remain in achieving mechanical performance suitable for practical applications of these systems.
Here we introduce a compliant battery design strategy that relies on utilizing mechanically robust current collector geometries such as spirals, serpentine, or helical springs to serve as a structural support for the rest of the battery components. We demonstrate the concept on the example of silver-zinc battery chemistry, due to its high energy density and intrinsic safety.
The batteries based on helical band springs were comprised of wire-shaped batteries with improved resilience to fatigue. They showed a high specific capacity, ranging from 1.2 - 1.8 mAh cm-1 at 0.5C discharge, and retained their electrochemical performance over 17,000 flexure cycles at a 0.5 cm bending radius. Serpentine and spiral shaped batteries, with a capacity of 3.5 mAh cm-2, retained their electrochemical properties when enduring coplanar stretching up to 200% of its original length.