Perchlorate Salts of Crown‐Ether‐Encapsulated Li Cations: Syntheses, Structures, Spectra, and Conductivity

Extensive scientific research is currently carried out globally to improve the performance of rechargeable batteries based on lithium ions and to develop new, especially solid‐state battery systems. Herein, results of preparative investigations of Li[ClO 4 ] with crown ethers of different ring sizes are presented. The three new coordination compounds [Li 2 (12cr4) 3 ][ClO 4 ] 2 , [Li(15cr5)(acetone)][ClO 4 ], and [Li(dibenzo‐18cr6)(H 2 O) 2 ][ClO 4 ] are prepared in crystalline purity and high yield. The crystal and molecular structures are determined by single‐crystal X‐ray diffraction. In addition, the already known structure of [Li(18cr6)(H 2 O) 2 ][ClO 4 ] is redetermined and confirmed. They all consist of discrete molecular cations in which Li + is encapsulated in the respective crown ether ring and perchlorate anions. In all four compounds, the coordination environment of the Li + ion contains besides O atoms of the crown ether molecules addition donors, i.e., an O atom of an empty 12cr4 ring, the O atom of an acetone molecules or those of water molecules. Thermal investigations reveal melting points around 100 °C. The measurement of the electrical conductivity of [Li 2 (12cr4) 3 ][ClO 4 ] 2 gives a value of 3.5 ×10 −6 S/cm, which is ≈1000 times smaller than that of currently used Li‐based electrolytes.