Structural Supercapacitors Using PEG-Based Epoxy Resins as Polymer Electrolytes

G.E. Lindberg, C. Ciocanel, C.C. Browder
Northern Arizona University,
United States

Keywords: supercapacitor, power storage, multifunctional material, gel polymer electrolyte, conductive epoxy resin

Summary:

The growing popularity of portable electronics, hybrid and electric vehicles, and renewable energy all demand a common solution: lightweight, low-volume, and safe power storage. To that end, we have developed a multifunctional material that simultaneously withstands mechanical loading and stores power. Inspired by the morphology of electric double layer supercapacitors, this composite system is composed of carbon fiber electrodes and a glass microfiber separator bound by a stable, solid-state gel polymer electrolyte (GPE). While poly(ethylene glycol) (PEG) has long served as a polymer host for solid and gel polymer electrolytes, efficiency in fabrication and performance called for the development of a new class of PEG-based epoxy resins. The GPE is thus prepared as a prepolymer that can be applied to the electrodes and separator in its liquid form, taking maximum advantage of the surface area at the electrode-electrolyte interface. The liquid prepolymer then cures to its solid phase in contact with the electrodes, which allows for retention of electrode-electrolyte contact and subsequent benefits to mechanical properties and interfacial resistance. Notably, the epoxy-based GPE is formulated with no waste stream. This presentation will detail the development of the GPE, whose conductivity approaches 10-3 S/cm, along with efforts towards improving its ionic conductivity and mechanical strength. Performance in structural supercapacitors, including results from capacitance and flexure testing, will also be discussed.