Ionic Liquid (IL) Compatibilization of Macropore-Infused Nanocomposite Emulsion Thermosets (MINETs) for Structural Ion Transport

The point of failure in many supercapacitor and battery applications is the separator between electrodes. Failure occurs in many separators due to the weak connections between the separator and electrodes. Mechanically robust separators can improve lifetime performance, safety, and reliability of energy storage devices. For applications in structural energy storage separators, we propose using macropore-infused nanocomposite emulsion thermosets (MINET). MINETs are a class of bicontinuous resin composites with working fluid networks and embedded nanoparticles, stabilized by surfactants. Ionic liquid (IL) MINETs were made using EMIM-BF4 as the working fluid with both super-activated carbon and silica nanoparticles. For the stabilizing surfactant, we employed copolymers with resin-IL amphiphilic nature. The ionic conductivity of MINET samples were tested and found to be on the order of 10E-5 S/cm, commensurate with commercial control membranes with 10 nm pores, but possessing higher mechanical properties and manufacturability. Device feasibility is presented with a proof-of-concept MINET capacitor involving a MINET electrode and separator layer. This is a promising step in furthering development of solid polymer electrolyte materials as separators, co-optimizing mechanical robustness and ionic conductivity to improve the performance of energy storage devices.