All-printed ultraflexible and stretchable asymmetric in-plane solid-state supercapacitors (ASCs) for wearable electronics

Increasing demands for portable and wearable electronics have stimulated considerable efforts to develop ultraflexible, stretchable and high-power supercapacitors. Existing stretchable supercapacitors are characterized by poor energy density, low stretchability and cumbersome fabrication process limit its practical application. How to enhance the energy densities and stretchability while simplify the fabrication process is a critical challenge for achieving the high-performance stretchable supercapacitors. Herein, we propose a simple and efficient fully-printing approach to manufacture the stretchable asymmetric supercapacitors, the functional layers are directly printed onto stretchable textile substrates in the order of silver current collector, cathode electrode, anode electrode and gel electrolyte. To the best of our knowledge, all-printed ultraflexible and stretchable asymmetric supercapacitors with ultrahigh energy density are first fabricated from two kinds of functional screen printing inks. The stretchable asymmetric supercapacitors using Ag@PPy@MnO2 cathode electrode and activated carbon anode electrode display an ultra-high energy density of 0.0337 mW h cm(-2) at a high power density of 0.38 mW cm(-2). In addition, its capacitance retention reaches 90.8% after 5000 cycles and 86.2% after 40% stretching strain. Furthermore, these asymmetric supercapacitors exhibit ultra-flexibility and mechanical stability at severely flexible states (including stretching, twisting, crimping and winding), and a red LED (2.8 V) is stable alight and powered by tandem asymmetric supercapacitors.