Fractal-inspired interconnect designs for stretchable/foldable batteries and soft device systems

An important trend in electronics involves the development of materials, mechanical designs and manufacturing strategies that enable the use of unconventional substrates, such as polymer films, metal foils, paper sheets or rubber slabs. The last possibility is particularly challenging because the systems must accommodate not only bending but also stretching, sometimes to high levels of strain (>100%). Although several approaches are available for the electronics, a persistent difficulty is in energy storage devices and power supplies that have similar mechanical properties, to allow their co-integration with the electronics. Here, we introduce a set of materials and design concepts for a rechargeable lithium ion battery technology that exploits thin, low modulus, silicone elastomers as substrates, with a segmented design of the active materials, and unusual fractal inspired interconnect structures. The result enables reversible levels of stretchability up to 300%, while maintaining capacity densities of ~1.1 mAh/cm2. The fractal inspired interconnects are also exploited, together with the idea of soft microfluidics and structured adhesive surfaces, to achieve ultralow modulus, highly stretchable systems that incorporate assemblies of high modulus, rigid, state-of-the-art functional elements. The outcome is a thin, conformable device technology that can softly laminate onto the surface of the skin, to enable advanced, multifunctional operation for physiological monitoring in a wireless mode.

About Yihui Zhang

Yihui Zhang is postdoctoral researcher at Northwestern University in Evanston, Illinois. He works with Professor Yonggang Huang to develop mechanics theory and novel designs of stretchable/flexible electronics, and soft robotics.

Link to video introducing stretchable lithium-ion batteries