Roll-to-roll 3D printing of flexible and transparent all-solid-state supercapacitors

Roll-to-roll (R2R) fabrication of flexible and transparent all-solid-state supercapacitors (FT-ASSCs) is extremely challenging because of the classic trade-off between transparency and capacitance. In this work, we develop fully three-dimensional (3D)-printed, sandwich-type FT-ASSCs comprised of 3D line-patterned carbon black (CB)/Ag/CB electrodes on a transparent dialysis membrane (DM) separator. By tailoring the line pitch of the 3D electrodes, our FT-ASSC is able to achieve more than 80% optical transmittance and significantly higher areal capacitance than an opaque ASSC. More importantly, the performance of 3D-printed FT-ASSCs is unrestricted by the transparency-capacitance trade-off, and they exhibit a superior capacitive figure of merit value compared with state-of-the-art FT-ASSCs reported in the literature. Additionally, our FT-ASSCs demonstrate excellent cyclic stability and mechanical robustness because of the chemical and mechanical stability of the DM separator and effective encapsulation of polyurethane. The single-flow 3D printing technique introduced here can meet the requirements for industrial-scale R2R manufacturing of energy storage devices.