Study on Ionic Plastic Crystals As Lithium-Ion Electrolytes

Ionic plastic crystals (IPC) have a highly symmetrical crystal structure similar to CsCl or NaCl, as a result of utilizing the energy associated with crystal melting for molecular rotational motion [1,2]. The introduction of lithium salt into these materials can realize the lithium-ion electrolytes enhanced conductivity compared to pure plastic crystals [3]. However, this operation concurrently reduces the plastic crystal's melting point, thereby limiting the temperature range existing as an electrolyte [3]. Therefore, this study explores two avenues to discover materials featuring the plastic crystal phase with the broad temperature range and the high ion conductivity. In the first approach, attention is directed towards the anion structure of lithium salts. Conventionally, the anion of lithium salts is selected to be same with one of the plastic crystals. However, investigating various combinations of plastic crystals and lithium salts holds promise. The second approach is development of additives. Increasing the amount of additives similar to lithium salts causes the disadvantage of narrowing the temperature range of the plastic crystal phase. Therefore, we seek to investigate if this disadvantage can be avoided through anion or additive modification. Detailed findings from these investigations will be reported on the day of the presentation. [1] J. Pringle, Phys. Chem. Chem. Phys. 15 , 1339 (2013). [2] J. Pringle, P.C. Howlett, D.R. MacFarlanea and M. Forsyth, J. Mater. Chem. 20 , 2056 (2010). [3] M.L. Thomas, K. Hatakeyama-Sato, S. Nanbu, and M. Yoshizawa-Fujita, Energy Adv. 2 , 748 (2023).