Designed fabrication of carbonized paper-supported electrode from cellulose fibers/polydopamine/metal-organic frameworks for flexible supercapacitor

Metal-organic frameworks (MOFs), as a class of organic-inorganic hybrid materials, possess high porosity, large surface area, and adjustable structure, showing great application potential in supercapacitor. MOFs-derived porous carbon is considered to be a candidate electrode material for supercapacitors due to its high conductivity and efficient ion diffusion. However, severe stacking and low mechanical strength of MOFs-derived porous carbon limits its practical application. In this work, Fe-MOF grows on cellulose fibers (CF) with polydopamine (PDA) as an anchoring agent for fabricating CF/PDA/Fe-MOF paper. Carbonized paper-supported electrode is prepared via carbonization process. Carbonized paper substrate improves the dispersion, accessibility, and processability of Fe-MOF-derived porous carbon. And a large amount of N species in PDA can be transformed into N-doped carbon for further improving the conductivity of carbonized paper. Moreover, the Fe3+ in Fe-MOF are converted into Fe2O3 particles and embedded in the carbon skeleton of Fe-MOF-derived porous carbon, providing additional pseudocapacitive active sites. Benefiting from the pore structure, N doping, and pseudocapacitive active substances, the carbonized paper-supported electrode shows an impressive volume specific capacitance of 93.4 F cm−3 at 0.5 mA cm−2 current density and good rate capability with 84.1% capacitance retention at 10 times current density. Carbonized paper-supported electrode also has good electrochemical stability with 94.5% capacitance retention after 10000 charge-discharge cycles. In addition, carbonized paper-supported electrode exhibits enhanced flexibility because the loading of Fe-MOF-derived porous carbon improves the displacement space of carbonized fibers. This work provides a novel strategy for developing new carbonized paper-supported electrode for flexible supercapacitors.