Solid electrolyte based on 2-adamantanone for all-solid-state lithium-ion batteries

Solid-state batteries are considered the next step in battery technology. Materials investigated for application as solid-state electrolytes are mainly oxide ceramics, sulfidic (glass-) ceramics, and polymers. Besides these, another class of solid electrolytes with promising properties is based on plastic crystals. Especially due to their waxy behavior, they promise good interfaces within a solid-state battery. In this work, a new plastic crystal, 2-adamantanone, is investigated as basis for a solid electrolyte for the first time. Its large temperature window from − 95 to 255 °C for its plastic (conductive) state and the high dipole moment of 3.4 D make it a promising material for battery application. The mixture with a lithium salt was investigated thermally with TGA and DSC revealing stability in a large temperature range from − 30 to + 80 °C. IR investigations show the dissociation of the conductive salt, which is necessary for the lithium ion conduction. The ionic conductivity of the electrolytes reaches values up to 1.4·10−4 S/cm at room temperature with a very low activation energy of only 0.32 eV.