3D Printed Freestanding Electrodes for High Energy Density Batteries

Abstract

The global surge in energy consumption, as well as a rise in greenhouse gases, has created an urgent need for high-capacity battery materials to store intermittent, renewable energy sources such as wind and solar. Directly increasing electrode mass loading using the traditional slurry coating fabrication process introduces unavoidable issues such as slowed kinetics and thermal degradation. Freestanding electrodes are a great alternative as they eliminate the need for inactive components (i.e., binder, additive carbon, and current collector) and shorten the fabrication process. In this work, carbon microlattice templates are designed and fabricated through the use of 3D stereolithography, which allows for design flexibility of any shape or geometry, followed by pyrolysis to create porous hard carbon. These hard-carbon templates are then subjected to a ferrocene/sulfur reaction to grow iron sulfide that serves as active material, which has a theoretical specific capacity higher than that of commercial graphite. The design utilizes controlled microchannels that facilitate ion transport through charging and discharging cycles. The addition of FeS led to a specific capacity of 1204.2 mAh g-1 during cycle two with a current density of 500 mA g-1, which is much higher than that achieved with the control carbon template (≈37.3 mAh g-1 at 300 mA g-1). These results will advance the development of composite electrodes as well as shine light on the immense potential to develop high energy density batteries utilizing 3D printing.