Fabrication of 5 V High-Performance Solid-State Asymmetric Supercapacitor Device Based on MnO2/Graphene/Ni Electrodes

To reach high energy density and excellent cycle stability, an asymmetric supercapacitor device combining a high-power electric double-layer capacitor (EDLC) anode battery-type cathode has been designed fabricated. A binder-free strategy was used to prepare by coating graphene (G) on Ni foam (Ni), then electrodepositing MnO2, followed calcination process. The potentiodynamic (PD) electrodeposition cycles of MnO2 onto significantly impact the electrochemical properties. Benefiting from hierarchical structure process 75 C/G/Ni hybrid cathode, potentiostatic (PS) PD for demonstrates specific capacitance 691 F g?1 at 2 g?1. enhanced capacitive performance can be attributed synergistic effect between nanosheets graphene, in which serve as ideal support matrix conductive channels. Furthermore, fabricated with (G + AC)/Ni anode, respectively, carboxymethyl cellulose–potassium hydroxide (CMC-KOH) gel electrolyte. C/G/Ni//(G (ASC) exhibits maximum 43 kW kg?1 power 302 W potential window 1.6 V maintains good cycling stability 88% retention (over 5000 cycles). Four solid-state supercapacitors stack connected series display effective 5.0 working increase voltage output device. charged using 18,650 Li battery +3.8 30 s discharged six white LEDs 20 min. facile fabrication remarkable MnO2/G/Ni make it promising electrode candidate conversion/storage devices.