A silicon-air battery utilizing a composite polymer electrolyte

Gel polymer electrolytes (GPEs) made of blends of ionic liquids and polymer elements, are of high interest as electrolytes in batteries. They possess the high mechanical stability and non-fluidity of solids, together with the thermal and electrochemical stabilities of ionic liquids. In the present work we studied GPE, comprised of a EMI·(HF)_2.3F ionic liquid and 2-hydroxyethyl methacrylate polymer. Morphological characteristics, thermal, electrical, and electrochemical studies confirmed the ability of the GPE to serve as an electrolyte in an all solid Si-air battery. The ionic transport number, determined via the Wagner polarization technique, was found to be close to unity, suggesting ionic conduction domination over an electrical conduction. GPE containing 70 mol% ionic liquid showed a discharge voltage of 0.6 V over more than 850 h, in a discharge current of 0.1 mA cm^-2. This work demonstrates the feasibility of using gel polymer electrolytes in silicon-air batteries that offer unprecedented specific energy for powering low power devices.