Abstract
In this study, we developed new cross-linkable benzoxazine molecules comprising a spiro-twisted core and benzyl cyanide or benzonitrile groups to prepare semi-interpenetrating polymer network (s-IPN) electrolytes. The features of spiro-twisted core and cross-linking network derived from the cured benzoxazines play a crucial role in creating a high free volume and inhibiting the crystallinity. In addition, the incorporation of the nitrile group onto the crosslinked spiro-twisted molecular chains by covalent bonding would certainly enhance the miscibility of SPE membranes with lithium salts while maintaining good mechanical properties. On the other hand, the -CN groups would have more space for rotation and vibration to improve lithium migration owing to the presence of a high fractional free volume of spiro-twisted matrix. Along blending with poly (ethylene oxide) (PEO) electrolytes, a new type of CN-containing semi-interpenetrating polymer networks for solid polymer electrolytes (SPEs) has been achieved.