An “inverted load” strategy to fabricate interface-optimized flexible electrode with superior electrochemical performance and ultrastability
With the rapid development of portable electronics, flexible supercapacitor (SC) is highly desired for energy storage devices due to its fast charging, large capacitance and high energy density. However, inferior interfacial property is a common problem faced by many flexible electrodes, which would result in reduced electrochemical performance and limited stability. Herein, an “inverted load” strategy which on the contrary to the traditional "forward load" method, deposits the active material, the conductive layer and the flexible substrate sequently on a glass plate, followed by peeling off the whole film, is reported for fabricating an integrated flexible electrode. This innovative strategy contributes to the strong interlayer adhesion of the electrode, which is greatly benificial to improve the electrochmical property and stablity. In the integrated electrode, a silver nanowires (AgNWs) network is tightly embedded between the PEDOT:PSS buffer layer and the colorless polyimide (CPI) substrate, which endows this electrode with excellent conductivity and bending stability. A higher specific capacitance (15.8 mF cm-2 at a current density of 0.1 mA cm-2 ) and an enhanced capacitance retention of 92% after 10,000 CV cycles can be achieved for W0.71Mo0.29O3/PEDOT:PSS/AgNWs/CPI (WPAC) electrode with W0.71Mo0.29O3 as the active layer, while PEN/ITO/PEDOT:PSS/W0.71Mo0.29O3 (PIPW) electrode prepared by the traditional "forward load" method only reaches 8.0 mF cm-2 at the same current density with a poor electrochemical cyclic stability of 48% after only 1000 CV cycles. Taking advantage of the superflexibility of CPI substrate, the electrode can achieve outstanding flexible bending stability with the resistance of WPAC electrode increasing less than 1% and almost no capacitance loss after 10,000 times of bending with a curvature radius of 500 μm. This novel strategy might provide a new perspective on the design and fabrication of a transparent, stable and flexible electrode for electronic devices.