High-performance symmetric supercapacitor based on manganese oxyhydroxide nanosheets on carbon cloth as binder-free electrodes

• Thin-wall MnOOH grows on carbon fibers as a binder-less electrode.
• The smart architecture is beneficial to fast ion and electron transfer.
• The integrated electrode shows high capacitance and excellent cycle stability.
• The fabricated SSC exhibits high energy density of 32.5 Wh kg−1.

Three-dimensional (3D) material, as a promising candidate for supercapacitor electrodes, draws great attention all the time since it exhibits the enhanced capacitive performance comparing with the low dimensional nanoscale building blocks. Herein, we grow MnOOH on carbon cloth (CC) fibers by employing electrodeposition method. The morphology, microstructure and composition of the as-obtained samples were characterized by using FESEM, XRD, XPS, Raman and FTIR. The MnOOH nanosheets are grown vertically on CC fibers to form a thin-wall cell structure with open pores (donated as thin-wall MnOOH/CC), which can be directly acted as working electrode without other binders or conductive additions. The thin-wall MnOOH/CC electrode in the three-electrode configuration reveals a high specific capacitance of 330.2 F g−1 under a wide potential window of 1.7 V (ranging from −0.9 V to 0.8 V) as well as excellent cycle stability (6.3% decay after 5000 cycles). Furthermore, the symmetric supercapacitor (SSC) assembled by using thin-wall MnOOH/CC as both negative and positive electrodes shows an energy density of 32.5 Wh kg−1 at power density of 850 W kg−1 with a remarkable cycle lifetime (84.6% of the initial value after 10000 cycles). The unique thin-wall structure and binder-free electrode are responsible for the enhanced electrochemical performances.