Liquid crystals as additives in solid polymer electrolytes for lithium metal batteries

Abstract

The forefront of research for new electrolyte materials for tomorrow’s electrochemical energy storage technologies is based on thoroughly designed molecular architectures. Here, liquid crystals (LCs) mixed with poly(ethylene-oxide) (PEO) and lithium salts are proposed as solid polymer electrolytes (SPEs) for application in lithium-metal batteries. The PEO matrix comprises the LC, which gives orientational properties, whereas the PEO chains with lithium salts are responsible for the ionic conductivity. N-(4-Methoxybenzylidene)-4-butylaniline (MBBA) is used as proof-of-concept and new LC molecules are developed for further research. Ionic conductivities (7·10–4 S·cm−1 at 40 °C) up to three times higher than the reference without LC are achieved. In addition, the SPEs are characterized electrochemically, thermally and by polarized optical microscope demonstrating the preservation of the liquid crystalline behavior even after mixing with PEO and lithium salts.Graphical abstract