Eutectogels: A New Class of Solid Composite Electrolytes for Li/Li-Ion Batteries

Here, we introduce deep eutectic solvent (DES)–silica composites as a promising candidate for solid composite electrolytes (SCEs). The proposed DES-based gel electrolytes, further referred to as eutectogels (ETGs), are characterized by high ionic conductivity (1.46 mS cm–1), thermal (up to 130 °C), and electrochemical stability (up to 4.8 V) and are chemically inert to solvents and water. These ETGs can be easily processed and potentially at lower costs compared to ionic-liquid-based composite electrolytes. The good prospects of ETGs for application in Li/Li-ion batteries are demonstrated by stable cycling of Li/ETG/LiFePO4 cells over 100 cycles at C/10.