Alumina foam-based electrolyte for thermal batteries: design and performance evaluation

Thermal batteries are predominantly used in defense applications owing to their exceptional shelf life and high-power discharge capabilities. However, the electrolytes conventionally used in these batteries are typically fabricated via cold pressing, which imposes significant manufacturability limitations, particularly when aiming for thin and wide formats, and they require labor-intensive processing. Although numerous approaches have been explored to address these constraints, commercially viable alternatives have yet to be realized. In this paper, we present a strategy in which porous alumina foam, infiltrated with molten salt, functions as a high-performance electrolyte suitable for thermal battery systems. We characterized the chemical compositions and microstructures of the ceramic foam and thermal battery unit cells using scanning electron microscopy combined with energy dispersive spectroscopy. Through a systematic evaluation, we identified the pore structure, separator thickness, and porosity of the foam as the key parameters governing the discharge behavior. Our approach presents a paradigm shift in electrolyte fabrication in that it offers a scalable and structurally robust alternative to conventional pellet-pressing techniques.