Preparation of porous manganese hydroxide film and its application in supercapacitors

Preparation of a manganese hydroxide film by electrochemically induced deposition method is reported here. The morphology and crystal structure of the film have been investigated by scanning electron microscopy and X-ray diffraction, respectively. The possible deposition mechanism of the film is also discussed. Moreover, the capacitive properties of the film have been evaluated by cyclic voltammetry and galvanostatic charge-discharge method. The results indicate that the morphology of the deposits depends on the amount and size of evolved H 2 bubbles, which can be adjusted by changing the composition of electrolyte and deposition current density. The capacitive properties of film are affected by the deposition parameters. The film prepared under the optimum deposition conditions shows excellent capacitive properties: high specific capacitance (493 F g -1 in 0.1 M Na 2 SΟ 4 aqueous solution from 0 to 1 V at a current density of I mA cm -2 ), high electrochemical reversibility and excellent long-term charge-discharge cycle stability (2.2% loss of the specific capacitance observed at the 2000 th cycle under the charge-discharge current density of 10 mA cm -2 ).