Multifunctional high strength and high energy epoxy composite structural supercapacitors with wet-dry operational stability†
We demonstrate the fabrication of multifunctional structural supercapacitors that maintain energy storage capability under both mechanical stresses and water immersion. This is based on the infiltration of bisphenol A ionic liquid epoxy resin electrolytes infiltrated into nanoporous silicon interfaces that play the dual role of charge storage and mechanical reinforcement of the energy storage composite material. These structural composites maintain full energy storage capability (5–8 W h kg−1) under tensile stresses over 1 MPa, with nearly 100% energy retention after 4000 cycles. We observe this mechanical and charge storage performance to be preserved through extreme water immersion conditions in contrast to conventional polymer-based solid-state electrolytes that spontaneously lose mechanical integrity under water immersion conditions. As structural energy storage is required to simultaneously maintain mechanical integrity, store charge, and operate in unpackaged environments exposed to humidity and wet-dry conditions, we demonstrate the first device architecture capable of all these conditions while demonstrating energy capability near current packaged commercial supercapacitor devices.