SKYDWELLER US INC. — Department of Defense STTR Phase I: AF20C-TCSO1

Description

Li-ion batteries have been a key enabler for unmanned aircraft over the past decade, but progress has stalled. When the solar impulse II aircraft flew around the world in 2016 using only solar cells and batteries, it used the highest performing Li-ion batteries on the market, achieving an energy density of 260 whr/kg. Nearly 5 years later, the best Li-ion batteries on the market have experience little improvement in energy density. Lithium-Sulfur (LiS) technology is often considered the next major leap for lithium-based batteries. These batteries, made of silicon anodes and sulfur cathodes, can increase the energy density by almost 10x versus graphite anodes. LiS offers the potential to reach energy densities up to 500 whr/kg in real-world applications. Unfortunately, current LiS batteries have been unable to achieve market adoption due to low cycle life and the need for pressurized packaging that is so heavy that it negates the weight savings of the cells themselves. This project proposes to overcome these limitations by utilizing self-healing polymer networks in order to mitigate mechanical instabilities that are the cause of current LiS challenges. The traditional use of liquid electrolyte in LiS batteries will be replaced with a solid polymer electrolyte to mitigate undesired polysulfide shuttle effects and improve thermal stability of the batteries. This approach will remove the need for heavy compressive mechanical housings, enabling the next leap in battery energy density.