DIRECT INK WRITING SOLID-STATE LI+ CONDUCTING CERAMICS FOR NEXT GENERATION LITHIUM METAL BATTERIES

Abstract

The global pursuit of safer and higher-capacity energy storage devices emphasizes the crucial link between the microstructures of electrochemically active materials and overall battery performance. The emergence of solid-state electrolytes featuring multi-layered, variable porosity microstructures presents fresh opportunities for developing the next generation of rechargeable batteries. However, this advancement also brings forth novel challenges in terms of device integration and operation. In this dissertation, solid-state Li-ion conducting electrolytes were 3D printed to enhance the performance of porous electrolyte layers within porous-dense-porous trilayer systems.LLZO-based garnet electrolyte scaffolds were fabricated via 3D printing using direct ink writing (DIW), facilitating the generation of scaffolds with minimal tortuosity and constriction in comparison to previous porous scaffolds manufactured through tape casting. Rheological techniques, including stress and time sweep tests, were employed to characterize the DIW inks and discern their conformal and self-supporting properties. The analysis focused on ink characteristics critical for Direct Ink Writing (DIW), emphasizing properties essential for achieving high aspect ratio printing and minimal constriction in 3D structures. Drawing from this ink research, two distinct 3D architectures, columns and grids, were fabricated. Column structures were utilized in assembling Li-NMC622 and Li-SPAN cells, with detailed discussions highlighting improvements in printing and sintering outcomes. Notably, NMC622, characterized by larger particle sizes, demonstrated complete infiltration within 3D printed porous networks, yielding a promising specific capacity of 169.9 mAh/g with minimal capacity fade. Further optimization involved integrating a porous 3D scaffold to facilitate SPAN infiltration in Li-SPAN cells, resulting in a specific capacity of 1594 mAh/g, albeit with significant capacity fade. The Li-S was implemented into a grid structure achieving 763 mAh/gS with less than 0.25% capacity loss over 16 cycles. Lastly, comprehensive morphology analysis was conducted to evaluate the effectiveness of our optimal DIW structures and to inform future enhancements of such cells.