Ideally pseudocapacitive behavior of amorphous hydrous cobalt-nickel oxide prepared by anodic deposition

Binary hydrous cobalt-nickel oxide with an amorphous structure (denoted as a-(Co + Ni)(OH)(2).nH(2)O) anodically deposited from a CoCl2.6H(2)O - NiCl2.6H(2)O solution with its Co:Ni ratio of 4:6 and pH 8.0 exhibited a very large pseudocapacitance of ca. 730 F g(-1) in 1 M NaOH. The electrochemical reversibility of this material was examined at various charging-discharging currents in 1 M NaOH with different temperatures. This binary hydrous oxide exhibiting ideally pseudocapacitive behavior (i.e., high reversibility, high specific capacitance, and high power property) has been demonstrated to be a potential candidate for the application of electrochemical supercapacitors. The morphology and rough nature of this deposit were demonstrated through means of atomic force microscopy. (C) 2002 The Electrochemical Society.