MnO2/polypyrrole-electrodeposited carbonized paper fiber-based for flexible asymmetric supercapacitors with high electrochemical and mechanical reliability

The rapid development of intelligent electronic products and wearable devices has stimulated the research up-surge on flexible supercapacitors. However, achieving supercapacitors with both high flexibility and high energy density remains a huge challenge. Herein, we develop a novel strategy to fabricate flexible asymmetric super -capacitor comprised of carbonized paper fiber/graphene/tannic acid (CGTA), manganese dioxide (MnO2) and polypyrrole (PPy) based film electrode. The electrode synthesized via electrochemical deposition avoided the necessity to use non-conductive binders and offered excellent electrochemical performance. The resultant MnO2@CGTA and PPy@CGTA film electrode exhibit high areal specific capacitance of 0.97 F cm-2 and 0.99 F cm-2 at a current density of 1 mA cm-2, respectively. The structural integrity provided by MnO2@CGTA and PPy@CGTA film electrode facilitated excellent electrochemical stability with capacitance retention of 89.93 % and 91.06 % after 5000 charge/discharge cycles, respectively. Furthermore, the flexible asymmetric super -capacitor (MnO2@CGTA//PPy@CGTA) is assembled and it demonstrates high specific capacitance of about 1.383 F cm-2 at 1 mA cm-2, excellent energy density of 192.08 mu Wh cm-2 at a power density of 0.5 mW cm-2, and good cycle stability of 90.12 % capacitance retention after 10,000 charge/discharge cycles. Even after 500 bending/unbending cycles, still about 86.43 % of its initial capacitance is retained.