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Lithium sulfur (Li-S) batteries offer higher theoretical specific capacity, lower cost and enhanced safety compared to current Li-ion battery technology. However, the multiple reactions and phase changes in the sulfur conversion cathode result in highly complex phenomena that significantly impact cycling life. For the first time to the authors’ knowledge, a multi-scale 3D in-situ tomography approach is used to characterize morphological parameters and track microstructural evolution of the sulfur cathode across multiple charge cycles. Here we show the uneven distribution of the sulfur phase fraction within the electrode thickness as a function of charge cycles, suggesting significant mass transport limitations within thick-film sulfur cathodes. Furthermore, we report a shift towards larger particle sizes and a decrease in volume specific surface area with cycling, suggesting sulfur agglomeration. Finally, we demonstrate the nano-scopic length-scale required for the features of the carbon binder domain to become discernible, confirming the need for future work on in-situ nano-tomography. We anticipate that X-ray tomography will be a powerful tool for optimization of electrode structures for Li-S batteries.

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The spray drying processes are widely used in chemical, ceramic, food, and pharmaceutical industries to produce both high-volume and high-value particulate products. Therefore, it is important to include a topic covering the spray drying process in the undergraduate curriculum of chemical and materials engineering students. In this article, we describe an Excel Visual Basic for Applications (VBA)-based educational module developed to assist students in learning the spray drying process. The module consists of two Excel files with VBA macro programs and teaching materials. The module focuses on the design of spray drying process conditions to produce the particulate product with desired moisture content at required production rate while satisfying the process restrictions on the inlet slurry concentration and the exhaust air temperature. Students are also asked to carry out the energy performance analysis of spray dryer equipped with an air-to-air heat exchanger that recovers the exhaust air heat to preheat the drying air. Using this module, students will enhance their theoretical and practical knowledge in drying processes, and gain analytical skills in drying process energy optimization. K E Y W O R D Senergy recovery, Excel VBA simulator, mass and energy balances, modeling, spray drying