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Electrodepositing manganese oxide into graphene hydrogel provides a facile and effective way to make full use of structural features of the hydrogel and capacity advantage of manganese oxide. The electrodeposition conditions play a key role in the deposition of manganese oxide, but little is known about their effect on electrochemical properties of the hybrid electrodes. Here, we systematically clarify the influences of deposition parameters (including current density, deposition time, Mn2+ concentration and bath temperature) on the capacitive performance (including apparent capacitance, specific capacitance, rate capability, cycling stability and charge storage mechanism) of manganese oxide/graphene oxide hydrogel hybrid electrodes. Under the proper preparation conditions, the highest specific capacitance of 453.7 F g−1 is obtained, and 92.4% capacitance retention (419.2 F g−1) is maintained after 5000 charge/discharge cycles, indicating excellent charge storage capability and cycling stability. Electrodeposition conditions play a decisive role in the capacitive performance of the manganese oxide/graphene oxide hydrogel electrodes. Image 1 [ABSTRACT FROM AUTHOR]

Electrodepositing manganese oxide in a three-dimensional graphene architecture has barely been explored, and therefore an exploratory but systematic investigation was conducted. A series of manganese oxide/graphene hydrogel electrodes were prepared by galvanostatic technique. The effects of electrodeposition condition, including current density, deposition time, Mn2+concentration and bath temperature, on the morphology and capacitive performance of the deposits were investigated. Nucleation and growth processes of the deposited manganese oxide were then deduced. An optimal capacitance of 452.5 F g−1 was got. This study could provide insight into the crystallization mechanism for electrochemical preparation of MnO x /graphene electrode for advanced energy storage/conversion devices. • Nucleation and growth processes of manganese oxide in a porous graphene monolith. • Effect of deposition conditions on electrocrystallization process. • Improved capacitive performance and flexible application. [ABSTRACT FROM AUTHOR]