Composite batteries: a simple yet universal approach to 3D printable lithium-ion battery electrodes

Abstract

Printable energy storage is anticipated to facilitate innovation in the manufacture of flexible electronics and soft robotics by enabling direct integration of a power source into a system during the fabrication process. To this end, we have established a universal approach to develop 3D printable, free-standing electrodes with an embedded current collector for high-performance Li-ion batteries. This simple approach utilizes a well-dispersed mixture of active material, carbon nanofibers, and polymer to make castable or printable electrode inks. By tuning the ratios of these components in a series of inks, we have observed the effect each parameter had on the resulting rheological, electrochemical, and mechanical properties. Once properly balanced, free-standing electrodes of three common Li-ion battery active materials (i.e., lithium titanate (Li₄Ti₅O₁₂), lithium iron phosphate (LiFePO₄), and lithium cobalt oxide (LiCoO₂)) were prepared, each demonstrating excellent cyclability and rate capability. Finally, electrodes were successfully patterned using a direct ink writing method, and a fully-printed, working electrode plus separator electrode assembly were developed.