Freestanding Carbon Lattice-Based Composites for Lithium-Ion Batteries and Beyond

Abstract

Advancements in technology in conjunction with rising concerns of global warming have led researchers to search for sustainable and environmentally friendly energy sources. Wind and solar are promising alternatives to fossil fuels; however, storage of these renewable energy sources poses a significant threat to their viability. Lithium-ion batteries (LIBs) are ideal candidates to offset their intermittent nature, functioning as an excellent storage medium. In addition, LIBs have been playing a key role in personal electronics (computers, cellphones, etc.) and are ubiquitous. LIBs in electric vehicles (EVs) are also rising exponentially. However, lithium-ion batteries still face many challenges. Their electrodes are currently made based on the conventional wet film coating fabrication process that utilizes a slurry containing active material coated onto current collectors. This slurry coating technology challenges the production of thicker electrodes with less inactive components. Directly increasing electrode mass loading using the traditional slurry coating fabrication process introduces unavoidable issues such as slowed kinetics and binder 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 addition, it preserves the microstructures of the electrodes and alleviates agglomeration. 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 hard carbon. These hard-carbon templates are then subjected 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 and carbon networks for fast electron transfer. The composites show much improved electrochemical performance. These results demonstrate the potential for advancing the development of composite electrodes and shed light on the enormous potential for developing high-energy density batteries using 3D printing.