Alla Letfullina – Seminar/PhD Preliminary Defense – Tuesday, December 19, 2017 at 11:00 A.M.
JSNN – Alla Letfullina – Ph.D. Preliminary Defense/Tuesday Seminar
Candidate: Alla Letfullina
Advisors and Committee Chairs: Sung-Jin Cho, Ph.D. and Dennis Lajeunesse, Ph.D.
Time: 11:00 A.M. – 1:00 P.M.
Location: JSNN 209 Open Room2907 E. Gate City Blvd., Greensboro, NC 27401
Title: “Highly Ionically Conductive Molecular Rotation Based Solid Polymer Electrolyte.”
The demand for a powerful and safe battery has been on the rise during the last decade. However, even the state-of-the-art lithium-ion batteries cannot sustain this need due to a flammable liquid electrolyte which they utilize. Therefore, the development of a thermally and electrochemically stable solid electrolyte is essential. The most radical strategy in solid electrolyte advancement is the use of plastic crystals due to their high ionic conductivity which is nearing that of liquid electrolytes. This property stems from the molecular rotation of their end groups which aid the lithium ion transfer. Succinonitrile is the most popular plastic crystal currently explored as a solid-state electrolyte. However, there are many other nitrile-based materials which share the same qualities as succinonitrile that have not been studied for a solid-state battery application. Among these materials is glutaronitrile, which has never been explored as a solid polymer electrolyte and shares the molecular rotation property with succinonitrile. The preliminary results have shown that glutaronitrile based electrolytes have high ionic conductivities, 1.36 × 10-3 S cm-1 at 22.6 °C, and exhibit impressive battery performance. We were able to reach high discharge capacities of 180 mAh/g at 0.1C as well as stable cycling for 50 cycles at 2C with a lithium titanate (LTO) half-cell. These are promising results which expose a new pathway for solid state electrolyte research.