Microstructure in the transition region and steady-state region of ice-templated sintered lithium titanate Li4Ti5O12 materials fabricated with and without sucrose

This study provides insights into the influence of sucrose (a water-soluble additive) on microstructure evolution in the transition region and steady-state region in ice-templated Li4Ti5O12 materials. A scanning electron microscope was employed for the two-dimensional characterization of microstructure in the transition region. Sucrose reduced the height of the transition region, caused an early alignment of ice lamellae toward temperature gradient direction, and resulted in a fine, dendritic microstructure. The overall microstructure development in the transition region was markedly different with and without sucrose. The differences were rationalized based on thermal conductivity, constitutional supercooling, and instability of the planar interface. Three-dimensional characterization of the steady-state region using X-ray computed tomography revealed that sucrose caused increased branching of the primary ice dendrites through tip splitting. A majority of the secondary dendrites turned into neighboring primary dendrites, enhancing pore path complexity. Diffusion simulations were performed to quantify pore tortuosity, which increased with sucrose content. Graphic abstract

Automated summary

This study explores the influence of sucrose on microstructure evolution in ice-templated Li4Ti5O12 materials using scanning electron microscopy and X-ray computed tomography. Sucrose was found to reduce transition region height, induce early alignment of ice lamellae, and increase branching of primary ice dendrites, enhancing pore path complexity. Diffusion simulations showed that pore tortuosity increased with sucrose content.