Enabling Soft Electronics through Flexible, Printable and Stretchable Batteries

Soft electronics aims to bridge the gap between functional, high performance, electronic devices and our soft, compliant, and organic environment. The use of 3D printing and direct write techniques offers distinct advantages for the integration of functional electronic devices onto non-traditional substrates and for the realization of compliant devices. The development of flexible, printable, and mechanically robust energy storage devices, in particular, is a key for many of these applications and will facilitate innovation in the manufacturing of flexible electronics. We have explored multiple approaches, including a mechanically robust and flexible current collector based on a nonwoven carbon nanotube mat, we demonstrate highly stable, bendable and even creasable Li-ion batteries. Additive manufacturing and direct write printing approaches enable direct integration of a power source into a device during the fabrication process. We utilized a well-dispersed and directly castable mixture of active material, carbon nanofibers, and polymer to make printable electrode inks. We also demonstrated a dry phase inversion printing technique to generate porosity within a polymer matrix and a ceramic Al2O3 filler to control pore size distribution and tortuosity. This technology for both electrolyte and electrode inks is an enabling step toward direct integration of flexible power in confined areas or on non-planar device surfaces.