Wide electrochemical window ionic salt for use in electropositive metal electrodeposition and solid state Li-ion batteries

Abstract

A stable hydrophobic ionic crystalline solid comprised of the N-propyl-N-methylpiperidinium cation and hexafluorophosphate anion PP₁₃PF₆ exhibits a remarkably wide electrochemical window of 7.2 V. This high purity crystalline ionic salt has versatility for use as an electrolyte in the electrodeposition of reactive metals such as tin. Moreover, this ionic salt can be used as a solid state electrolyte in Li-ion batteries. Theoretical calculations indicate that this solid state electrolyte has vacant sites that are preferential for Li-ion conductivity with an energy barrier of 0.4 eV. Further, the ionic crystals exhibit molecular rotations which facilitate facile Li-ion transport.