Effects of Cross-Linking on Solid Polymer Electrolytes Prepared Via Polymerization-Induced Microphase Separation

Solid polymer electrolytes (SPEs) have been proposed as a means of suppressing lithium dendrite formation in high energy density, rechargeable lithium metal anode batteries. Upon repeated battery cycling, dendrites grow and span the electrolyte, resulting in premature and, often, catastrophic battery failure. It has been proposed that a SPE with high modulus and ionic conductivity could prevent this dendrite growth, but previous efforts have had limited success. Recently, the Lodge and Hillmyer groups reported on a novel polymerization induced microphase separation (PIMS) method for the production of an unprecedented high modulus, high conductivity cross-linked polystyrene and poly(ethylene oxide)/ionic liquid SPE with a bicontinuous morphology and excellent temperature stability. Through electrochemical impedance spectroscopy as well as mechanical and small angle X-ray scattering measurements the effects of cross-linking were quantified. Although little variation was seen in the elastic modulus with varying divinylbenzene, the domain size, ionic conductivity, and sample quality were all found to be dependent on crosslinker concentration.