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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. 

For batteries, thicker electrodes increase energy density, however, molecular transport limits the rate of charge/discharge for extracting large fractions of available energy. Mitigating transport limitations by increasing electrolyte conductivity and aligning the pores in the electrode microstructure are described. 

Increasing electrode thickness is one route to improve the energy density of lithium-ion battery cells. However, restricted Li+ transport in the electrolyte phase through the porous microstructure of thick electrodes limits the ability to achieve high current densities and rates of charge/discharge with these high energy cells. In this work, processing routes to mitigate transport restrictions were pursued. The electrodes used were comprised of only active material sintered together into a porous pellet. For one of the electrodes, comparisons were done between using ice-templating to provide directional porosity and using sacrificial particles during processing to match the geometric density without pore alignment. The ice-templated electrodes retained much greater discharge capacity at higher rates of cycling, which was attributed to improved transport properties provided by the processing. The electrodes were further characterized using an electrochemical model of the cells evaluated and neutron imaging of a cell containing the ice-templated pellet. The results indicate that significant improvements can be made to electrochemical cell properties via templating the electrode microstructure for situations where the rate limiting step includes ion transport limitations in the cell.