Solid-state, flexible, high strength paper-based supercapacitors

We present a novel way of fabricating solid-state, flexible, high-strength, environmental-friendly all-paper-based supercapacitors. Microfibrillated cellulose (MFC) and multi-walled carbon nanotubes (MWCNT) were used to fabricate the electrode sheets. The solid polyelectrolyte (polyethylene oxide and lithium chloride) was doped in MFC to serve as separator layer. The specific capacitance was calculated to be 154.5 mF cm−2 at 20 mV s−1 from cyclic voltammetry. This value is significantly higher than most flexible supercapacitors reported in the literature. The paper-based supercapacitors have excellent mechanical properties compared to the conventional liquid or gel based soft supercapacitors, with tensile strength being 1 MPa and Young's modulus being 123 MPa. Moreover, the specific capacitance remained the same when the supercapacitors were bent under different curvature.