Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Physical Chemistry

Increasing demand for power supply sources with high energy density and highpower density for use in various applications in recent years motivates researchers toward the supercapacitors field. In this study, firstly, the electro generation of the base by cathodic reduction from iodate ions bath was used successfully to facile and ease preparation of homogeneously distributed Co(OH)₂ over graphite felt (GF) substrate to utilize the GF substrate' high surface area without any modifications with a good capacitive performance. Moreover, this film also is used to enhance the capacitance performance of Ni(OH)₂ via preparing a binary hydroxide electrode [S, Ni/Co(1:1)] by sequential electrodeposition. [S, Ni/Co(1:1)] possesses a high specific capacitance of 1240.5 F g⁻¹, the energy density of 62.03 W h kg⁻¹ at a power density of 2870.21 W kg⁻¹, and the value is retained to 47.56 W h kg⁻¹ at a high power density of 34442.60 W kg-1 indicating the superb rate performance of this electrode material. Secondly, graphene layers are successfully synthesized on the surface of the recycled graphite rod from the exhausted Zinc-Carbon battery using the simple electrochemical exfoliation method.The HQ redox reaction is greatly enhanced via exfoliated graphene surface giving a high specific capacitance value (693.94 mF cm⁻²). Also, the exfoliated graphene surface used as a substrate for the binary Ni/Co hydroxide to display one of the highest reported specific capacitance values for the binary Ni/Co hydroxide (3646.63 F g⁻¹).

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